3D-printing Inherently MR-visible Accessories in Aiding MR-Guided Biopsies

3D-printing Inherently MR-visible Accessories in Aiding MR-Guided Biopsies | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Method Article 3D-printing Inherently MR-visible Accessories in Aiding MR-Guided Biopsies Yanlu Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4234954/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 05 Aug, 2024 Read the published version in 3D Printing in Medicine → Version 1 posted 11 You are reading this latest preprint version Abstract Background Hard plastics are typically invisible in MRI images, while fluids are not. Objects manufactured using traditional Fuse Deposition Modelling (FDM) 3D-printing techniques are prone to leakage. 3D-printers which use UV-hardened resin to form objects possess a trait that is considered a technical inconvenience: Objects created using these techniques are inherently liquid-tight, and hollow parts require addition of drainage holes for uncured liquid resin to escape. If this is not done liquid resin will remain inside the object, which in some cases is the desired outcome. Digital Light Processing (DLP) is an affordable 3D-printing technique using UV-hardened resin. The technique also possesses superior dimensional accuracy and the ability to recreate fine details. Purpose We devised a method to produce an inherently MR-visible accessory using DLP technology with low dimensional tolerance to facilitate MR-guided breast biopsies. Methods By hollowing out the object without adding drainage holes and tuning printing parameters such as z-lift distance to retain as much uncured liquid resin inside as possible, objects that are inherently visible in MRI scans can be created without further treatment. Results Objects created through our method are simple and cheap to recreate, have minimal manufacturing steps, and are shown to be dimensionally exact and inherently MRI visible to be directly used in various applications without further treatment. Conclusion While this method may not always be suitable, we demonstrate that this process is viable in creating highly accurate objects that are inherently visible in MRI scans using equipment that is easy to obtain and trivial in cost. Rapid prototyping medical devices phantoms biopsy radiology Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Introduction In recent years, the widespread availability of cost-effective 3D-printers has revolutionized manufacturing and prototyping. In the field of biomedical engineering, 3D-printing has been used for a variety of applications, from creating bone models to tablet casings for medication 1 , 2 . 3D-printing phantoms for radiology equipment is another useful application since individual phantoms are often designed with specific purposes and are costly. Here we present a novel and relatively easy method of 3D-printing objects that are natively visible in typical MRI scans with DLP 3D-printers using an unorthodox printing technique. 3D-printing MRI phantoms Hard plastics are generally invisible in typical MR images, hence 3D-printed MRI phantoms must be designed and printed hollow to contain some form of liquid, which are typically MR visible. A challenge with traditional Fuse Deposition Modelling (FDM) 3D-printing technology is that creating liquid-tight objects is challenging. In FDM printing, an object is formed layer by layer using melted plastic. Micro-holes may arise between the individual layers of 3D-printed material, from which liquid may slowly seep through. While it is possible to create liquid tight containers using FDM techniques, the process is not trivial, typically involving fine-tuning printing parameters, and will often sacrifice spatial accuracy. Elaborate post-processing treatment of an object may also be applied, but additional materials and equipment may be necessary. Even then, success is not guaranteed. Furthermore, FDM 3D-printers lack the ability to create finely detailed parts. Digital Light Processing More recently, another type of 3D-printing technique which utilizes UV-hardened resin plastics such as Selective Laser Sintering (SLS), and especially Digital Light Processing (DLP), has gained more prominence as availability increase and costs decrease. At the time of writing there is a wide selection of DLP 3D-printers which are priced as consumer electronics. The process of object formation using UV-hardened resin differs from FDM printing techniques. First, liquid UV-hardened resin is poured into a vat with a transparent film bottom. The vat is placed on top of a UV light source with LCD panel. During printing, a metal build plate is dropped into the vat, leaving only a thin layer between the bottom of the vat and the build plate. A pattern is shown through the LCD panel, exposing UV light to the thin layer or liquid resin, and curing it. The cured resin sticks onto the build plate and is then lifted from the bottom of the vat. After some time, the build plate lowers an appropriate amount again, leaving only a thin layer of space between the object and the bottom of the vat and the process iterates. DLP printing technology is far superior in recreating details in parts than traditional FDM printing technology can achieve, and has been previously used to create phantoms for measuring dimensional accuracy in MRI scans 3 , 4 . DLP’s ability to recreate details has been shown to be suitable in printing dental models demanding a high degree of accuracy 5 , 6 . Objects created by curing resin in such fashion is also inherently liquid tight 7 , 8 . To save on material costs, objects are typically hollowed out, leaving only the outer shell and perhaps some structural supports in the middle. Unhardened resin may get trapped inside during the printing process; hence drainage holes are inserted on the part towards the bottom of the build plate for the liquid resin to drain out into the vat during printing. However, if this is not done, liquid resin will remain trapped inside, which will be visible in MR images. We take advantage of this phenomenon, together with DLP’s high dimensional accuracy and ability to recreate fine details, to create objects that are inherently visible in MRI scans with low spatial tolerances cheaply and effectively. MR-guided Biopsy One such application for this approach is to manufacture a MR-visible grid system for MR guided breast biopsies. During MR guided biopsies, MR images are taken of a patient’s breasts with a dedicated MR breast coil with a spatial localization system towards the side of the breast of interest. First, MRI scans are used to locate a suitable region to extract tissue samples in the breast, the localization system is then used to guide the biopsy needle toward the region of interest as on the MRI scans. This localization system is typically in the form of a grid made of hard plastic. Since the grid itself is MR-invisible, the grid must be pressed tight to make an imprint on the skin. This is not always possible as moving the grid on a rail system has limits, and since breast tissue is not infinitely deformable, the corresponding location of a target region might not be possible to obtain imprints on. This poses a challenge when trying to correlate the region of interest for the biopsy with the spatial guides during the procedure, which may result in physicians cancelling the procedure due to lack of confidence. This is not ideal since MR guided biopsies are performed only as necessary when all other methods of diagnostics is deemed unsuitable 9 . Purpose Here we design, manufacture, and evaluate the feasibility of using DLP 3D-printing technology to produce an equivalent localization grid for MR guided biopsies that is inherently visible in MRI scans to facilitate the localization process between a target region and spatial guides for the biopsy entry point. Materials and Methods Funding This work was supported by the Swedish General Medical Fund under Grant FOUI-973889. Part Design Using 3D CAD software (Onshape, www.onshape.com), a model of the MR biopsy grid with the exact grid dimensions was created. The model is designed to fit inside the existing grid as an insert. The model then expanded 1.4mm in all directions to act as an outer hardened shell to contain liquid resin (Fig. 1). Slicing Slicer software is used to convert a 3D-model into a format which 3D-printers operate on. Anycubic’s own proprietary slicer software Photon Workshop (V.2.1.24) was used since it is guaranteed to be compatible with our 3D-printer. Most slicer software for DLP printers have similar features to prepare a model for printing. These features include hollowing out a model to save on printing costs, and correspondingly, have a feature to insert holes into the model at any given location for the unhardened resin within the model to leak out during/after printing. Here we do not wish for the unhardened resin to leak out, and hence will not insert any holes into the model, but we do wish to “hollow” out the model, creating a wall 1.4mm thick (Fig 2A). Support generation is also another crucial step in preparing the design for 3D-printing which is also typically handled by the slicer software. In the final printing protocol we established, the model was placed slightly at an angle (30 degrees), and above (7mm) the build plate, as this is the most robust way of printing the part (see Results). Photon Workshop’s automatic support generator was used to generate necessary support to build the part as specified (Fig. 1D). Detailed slicer parameters including support generation parameters for the final object are found in (Table I). 3D-printing A Photon Mono (Anycubic, https://www.anycubic.com/) was used to perform 3D-printing. A black tough (“ABS-like”) resin (Primacreator, article number 24592) was used for the final object. Different resin types were also used during testing, such as “standard” resins in different colors (grey PV-RESIN-B405-0500-N and transparent PV-RESIN-B405-0500-CL) and water washable resin (PV-Resin-B405-1000-SK). The curing times are slightly different for the different types and colors of resin, so depending on the color of the filament, the curing times for each layer (and “first layers”) need be adjusted accordingly. For the print to be filled with liquid resin during printing, lift height after each layer was adjusted such that the part never lifts above the level of the liquid resin still in the vat. This may require manually filling the vat with fresh liquid resin in the middle of the printing process. 3D-printing is not an exact science and requires iterative improvement to achieve the desired results. Multiple prototypes were manufactured with various changes in design, printing parameters, and resins to achieve a robust printing process. The total print time depends on various printing parameters. Using parameters used for the final object (Table I), the total print time is approximately 6 hours and 14 minutes. Post-production Residue liquid resin remains on the surface after the print is completed, so the part still needs to be handled with caution (Fig 2E). The object was removed from the print bed and the supports removed by hand in an isopropanol solution (40%) bath while wearing protective equipment. It was then further cured outdoors under the sun (summertime) for approximately 15-20 minutes. When sunlight is not easily accessible, UV light can also be used, including dedicated “washing and curing” equipment offered by different DLP 3D-printer manufacturers. MRI Scanning The finished part was then fitted onto the existing grid (Fig. 3A, B) and scanned with breast phantoms to assess visibility of the grid in MRI images. Test scanning was performed on a GE Signa Premiere 3T MRI Scanner (Milwaukee, USA) with a 16-channel breast coil capable of MR-guided biopsy procedures (NeoCoil), with one lateral side of the coil replaced with the grid setup as standard MR-guided biopsy protocol (Fig. 3C). Both T1- and T2-weighted MRI sequences from our MR biopsy protocol used at Karolinska University Hospital were used to assess grid visibility in typical MRI scans. The T1-weighted sequence is an axial 3D spoiled gradient echo with a TE=1.7ms and TR=4.1ms, 340mm FOV with 360x360 in matrix size and a slice thickness of 0.7mm. The T2-weighted sequence is a 2D axial fast spin-echo, FA=111, TE=102, TR=4601, FOV=350mm, matrix size=320x320, and 3mm slice thickness. Results Since the designed part has many large flat surfaces, one would intuitively use one of such faces as the surface to adhere to the print surface (Fig. 2B). Experience shows that this makes the printing process more prone to failure (Fig. 2C) and the printing process is more robust when printing large flat surfaces at an angle (such that large surfaces are not printed at any single layer). The finished part should look and feel try to the touch before handling using bare hands. The UV hardened outer shell is capable of fully enclosing liquid resin inside without leakage unless cracks appear on the outer shell (see Discussion). This is visible for the prototype manufactured in transparent clear resin, made specially for investigating the degree of liquid resin inside the part (see supplementary materials). The liquid inside the produced grid object is shown to be clearly hyperintense on both T1 and T2-weighted MRI scans (Fig. 4). Tuning of printing parameters was needed to produce a filled object. Lowering the “Z-lift” length such that the lower edge of the unfinished print never lifts above the level of liquid resin remaining in the vat aids to retain liquid resin inside the part during print through vacuum suspension. Depending on size and shape of the vat, manually filling the vat with fresh liquid resin during print might be necessary. Figure 5 shows the difference between a grid fully filled with liquid resin versus one that is only partially filled with resin due to suboptimal printing parameters. Discussion Some downsides of the techniques are not only derived from the inherent downsides of the 3D-printing technique, but also from our unusual application of the technology. Any object produced in this manner must not only be 3D-printable in general, but the design must also allow for the MR visible sections to be fully enclosed by a hardened outer shell which lays additional restrictions during design. Experience indicates that at least 1.4mm thick is recommended for the part to be able to withstand normal handling. Since this method of production replies on liquid retention, the method of printing large objects in parts and then assemble them in post-processing in applicable in this case, hence the overall size of the object is restricted to the build volume the 3D-printer. Depending on the model of the 3D-printer, this may be a considerable restriction. Although more expensive 3d printers capable of producing larger parts do exist, they are also considerably more expensive to acquire and run. In addition, filling a part with liquid resin adds significant production costs to the part compared to draining it. Due to the brittle nature of the conventional UV-hardened resin, it would not be suitable to print such parts using the material. Fractures eventually appear on parts printing using “standard” resins (Fig. 6) after some time ranging from a couple of days to a year. The fractures eventually expand and deepen resulting in liquid resin leakages. The exact cause of this is currently unknown and is yet to be investigated. A tougher material such as “ABS”-like, or engineering resin, which are both harder, and more malleable in their cured state is preferred since parts printed using these resins has yet to show fractures in their outer shells, even after more than a year from initial printing. As the liquid resin will harden under UV-light, it is recommended that the parts are stored in a dark space with minimal/no UV light penetration. While transparent resins will cause more UV shine-through and hence will cure more quickly, darker opaque colored resins may retain liquid inside for longer. Systematic investigation of MRI visibility over time for different resin colors is yet to be done. But preliminary experiments show that independent of resin color, the produced parts will eventually fully harden, and as such no parts produced in this manner will be permanently MR-visible. This production process can be used to cheaply manufacture various devices designed to be inherently visible in MRI scans, such as phantoms and markers. Due to the great spatial accuracy of the 3D printing technology, the produced parts will not only be inherently liquid tight, but also dimensionally accurate for quality assessment applications. Conclusion Using relatively cheap and simple DLP 3D-printing techniques, we are able to construct dimensionally accurate parts that are inherently visible in typical MRI scans. The produced part is designed specifically to aid in spatial localization of tumors in MR-guided biopsy procedures, greatly simplifying the procedure and enhance confidence for personnel in the process. Declarations Authorship confirmation/contribution statement The sole author is the only contributor to the study and is fully responsible for all aspects of the study. Author’s Disclosure The author does not have any conflicts of interest to declare. Funding This work was supported by the Swedish General Medical Fund under Grant FOUI-973889. Author Contribution Y.W devised, and performed, and presented all aspects of this study. Acknowledgement The author would like to acknowledge Tomas Jonsson for facilitating the initial purchase of equipment. References Krkobabić M, Medarević D, Pešić N, Vasiljević D, Ivković B, Ibrić S. Digital Light Processing (DLP) 3D Printing of Atomoxetine Hydrochloride Tablets Using Photoreactive Suspensions. Pharmaceutics . 2020;12(9):833. doi:10.3390/pharmaceutics12090833 Nugroho WT, Dong Y, Pramanik A. Dimensional accuracy and surface finish of 3D printed polyurethane (PU) dog-bone samples optimally manufactured by fused deposition modelling (FDM). Rapid Prototyp J . 2022;28(9):1779-1795. doi:10.1108/RPJ-12-2021-0328 Ramachandran P, Noble C, Langton C, et al. A 3D printed phantom to assess MRI geometric distortion. Biomed Phys Eng EXPRESS . 2021;7(3):035004. doi:10.1088/2057-1976/abeb7e Rai R, Wang YF, Manton D, Dong B, Deshpande S, Liney GP. Development of multi-purpose 3D printed phantoms for MRI. Phys Med Biol . 2019;64(7):075010. doi:10.1088/1361-6560/ab0b49 Tsolakis IA, Papaioannou W, Papadopoulou E, Dalampira M, Tsolakis AI. Comparison in Terms of Accuracy between DLP and LCD Printing Technology for Dental Model Printing. Dent J . 2022;10(10):181. doi:10.3390/dj10100181 Park JM, Jeon J, Koak JY, Kim SK, Heo SJ. Dimensional accuracy and surface characteristics of 3D-printed dental casts. J Prosthet Dent . 2021;126(3):427-437. doi:10.1016/j.prosdent.2020.07.008 Qiu J, Hou K, Dyer BA, et al. Constructing Customized Multimodal Phantoms Through 3D Printing: A Preliminary Evaluation. Front Phys . 2021;9. Accessed October 2, 2023. https://www.frontiersin.org/articles/10.3389/fphy.2021.605630 Bieniosek MF, Lee BJ, Levin CS. Technical Note: Characterization of custom 3D printed multimodality imaging phantoms. Med Phys . 2015;42(10):5913-5918. doi:10.1118/1.4930803 Viehweg P, Heinig A, Amaya B, Alberich T, Laniado M, Heywang-Köbrunner SH. MR-guided interventional breast procedures considering vacuum biopsy in particular. Eur J Radiol . 2002;42(1):32-39. doi:10.1016/s0720-048x(01)00479-x Table Table I: Slicing, automatic support generation, and printing parameters. Setting Group Parameter Label Parameter Value Slice Settings Layer Thickness (mm) 0.05 Expose Time (s) 10 Off Time (Between exposure) 0.5 Bottom Exposure Time 40 Bottom Layers 10 Z Lift Distance (mm) 4 Support Shape Settings Top Contact Shape Default Contact Depth (mm) 0.4 Contact Diameter 0.8 Shape Cone Diameter (mm) 1.2 Length (mm) 2.0 Angle (degrees) 72 Mid Shape Cylinder Diameter (mm) 1.2 Bottom Platform Touch Shape Skate Touch Diameter (mm) 12.0 Thickness (mm) 1.00 Contact Shape Default Contact Diameter (mm) 0.60 Contact Depth (mm) 0.20 Raft Shape Default Raft Thickness (mm) 2.70 Raft Inner Thickness (mm) 1.00 Raft Angle 45 Support Generation Settings Hollow Mesh No Type Vertical AutoSupportAngle 70 Support Density (%) 70 Support Min Length (mm) 3.00 Additional Declarations No competing interests reported. Supplementary Files Sf1tranpresinfill.mp4 Cite Share Download PDF Status: Published Journal Publication published 05 Aug, 2024 Read the published version in 3D Printing in Medicine → Version 1 posted Editorial decision: Revision requested 05 Jun, 2024 Reviews received at journal 31 May, 2024 Reviewers agreed at journal 31 May, 2024 Reviews received at journal 30 May, 2024 Reviewers agreed at journal 30 May, 2024 Reviews received at journal 02 May, 2024 Reviewers agreed at journal 20 Apr, 2024 Reviewers invited by journal 15 Apr, 2024 Editor assigned by journal 11 Apr, 2024 Submission checks completed at journal 11 Apr, 2024 First submitted to journal 08 Apr, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-4234954","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Method Article","associatedPublications":[],"authors":[{"id":291166427,"identity":"fd622bcb-d8ef-42ac-abbb-2008c075b1b8","order_by":0,"name":"Yanlu Wang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAxklEQVRIiWNgGAWjYHACxgMQmvkwQwKxeqBa2JJJ1sJjTJxyg+NnDxzmYTgsb86/5rPBA4Y6OcJazuQlgLQY7pzxdnNCAsNhwlYZHMgxAGq5zbjhxtnNBxIYDiQ2ENRy/g1Yi/2GG2ceA7XU1RPWcgNiS+KG8z3MQIcxJxB0mOSNNwYH5xj8T95wg83YIMHgsCFBW/jO5xg+eFORZrvh/OHHkj8q6uQJ2qJwAOw8IJZIgDIIAXm4O/gPEKF8FIyCUTAKRiQAAHatQ+WbVcTdAAAAAElFTkSuQmCC","orcid":"","institution":"Karolinska University Hospital","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Yanlu","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2024-04-08 08:15:33","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4234954/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4234954/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s41205-024-00227-w","type":"published","date":"2024-08-05T15:57:14+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":54999951,"identity":"4e26aff2-f2a5-4915-ae34-e95b39ca9b80","added_by":"auto","created_at":"2024-04-19 18:33:10","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":154195,"visible":true,"origin":"","legend":"\u003cp\u003eCAD drawing of the grid insert. The object is designed to fit inside the existing MR-guided biopsy grid and to be printed hollowed out with a 1.4mm thick wall. Since no drainage holes exist on the part, uncured liquid resin will be retained inside the part which is visible in the MRI scans. It is designed such that the liquid retained inside has the exact same dimensions as the original grid used for biopsy.\u003c/p\u003e","description":"","filename":"1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/890b7d0c272c8adfa9b712d1.jpeg"},{"id":54999949,"identity":"c0d14a3f-53de-4af3-80ed-2c251aa95eb3","added_by":"auto","created_at":"2024-04-19 18:33:09","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1049612,"visible":true,"origin":"","legend":"\u003cp\u003eA: Slicer features: hollowing and drainage hole punching, are manipulated to retain liquid inside the part rather than draining it to save costs. B: Intuitive printing setup for this part with large, flat surfaces, this however causes layer adhesion issues and cause the print to fail easily (C). D: More robust printing layout with the part tilted at an angle (typically 30-60 degrees) and lifted slightly above the build platform with generated supports to hold up the part. This is more robust to printing failures (E).\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/b53ca55eac9c50fae4993258.png"},{"id":54999952,"identity":"5920356d-4916-4154-b12d-8e61d61cd11f","added_by":"auto","created_at":"2024-04-19 18:33:10","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":10232772,"visible":true,"origin":"","legend":"\u003cp\u003eA: The finished part inserts into existing MR-guided biopsy grid. B: the part on the grid in its retainer. C: The entire MR-guided biopsy setup on the scanner bed.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/2ee78349f604fb534794c2c9.png"},{"id":54999946,"identity":"4a1a8686-2d69-45c0-9d14-849553b9eccb","added_by":"auto","created_at":"2024-04-19 18:33:09","extension":"jpeg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":101761,"visible":true,"origin":"","legend":"\u003cp\u003eA: Even with MR breast phantoms which are extremely hyperintense in MR images, the grid insert is clearly visible in the scans. B: Grid insert in T1-weighted MRI scan with ROI statistics. C: Grid insert in T2-weighted MRI scans with corresponding ROI statistics.\u003c/p\u003e","description":"","filename":"4.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/79fae8e0ea7b74676255e7bf.jpeg"},{"id":54999947,"identity":"432a7545-1b89-41a2-b68d-1d6d94d93159","added_by":"auto","created_at":"2024-04-19 18:33:09","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":1241530,"visible":true,"origin":"","legend":"\u003cp\u003eDifferences in visibility in MRI scans between a grid insert prototype fully filled with liquid (A) and one which is only partially filled with liquid (B).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/1e65fb647f53d767d179ed54.png"},{"id":55002971,"identity":"b2a729e4-51f9-40df-9f7d-27554db2e1a8","added_by":"auto","created_at":"2024-04-19 18:41:10","extension":"jpeg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":34179,"visible":true,"origin":"","legend":"\u003cp\u003eUsing typical standard UV-hardened resin for DLP 3D-printers, cracks and fractures may arise on the outer cured shell of the part, which expands in time and may eventually cause leakages. Hence, “tough”, or “ABS”-like resin, or engineering resin may be preferred. Parts created by “tough” resins appear to be susceptible to cracks and fractures.\u003c/p\u003e","description":"","filename":"6.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/3ba77351684cb5939e272538.jpeg"},{"id":62298249,"identity":"a1b63829-fdf5-4767-8ec6-57183fb863dd","added_by":"auto","created_at":"2024-08-12 16:11:08","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":16360313,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/6ee57be1-7555-4c06-a320-61d67f48e4cd.pdf"},{"id":54999953,"identity":"71a64ce1-cccd-49d9-abff-4190a7351bdd","added_by":"auto","created_at":"2024-04-19 18:33:10","extension":"mp4","order_by":9,"title":"","display":"","copyAsset":false,"role":"supplement","size":15529510,"visible":true,"origin":"","legend":"","description":"","filename":"Sf1tranpresinfill.mp4","url":"https://assets-eu.researchsquare.com/files/rs-4234954/v1/f563a72e75d1b36edc702841.mp4"}],"financialInterests":"No competing interests reported.","formattedTitle":"3D-printing Inherently MR-visible Accessories in Aiding MR-Guided Biopsies","fulltext":[{"header":"Introduction","content":"\u003cp\u003eIn recent years, the widespread availability of cost-effective 3D-printers has revolutionized manufacturing and prototyping. In the field of biomedical engineering, 3D-printing has been used for a variety of applications, from creating bone models to tablet casings for medication\u003csup\u003e\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e,\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. 3D-printing phantoms for radiology equipment is another useful application since individual phantoms are often designed with specific purposes and are costly. Here we present a novel and relatively easy method of 3D-printing objects that are natively visible in typical MRI scans with DLP 3D-printers using an unorthodox printing technique.\u003c/p\u003e \u003cp\u003e3D-printing MRI phantoms\u003c/p\u003e \u003cp\u003eHard plastics are generally invisible in typical MR images, hence 3D-printed MRI phantoms must be designed and printed hollow to contain some form of liquid, which are typically MR visible. A challenge with traditional Fuse Deposition Modelling (FDM) 3D-printing technology is that creating liquid-tight objects is challenging. In FDM printing, an object is formed layer by layer using melted plastic. Micro-holes may arise between the individual layers of 3D-printed material, from which liquid may slowly seep through. While it is possible to create liquid tight containers using FDM techniques, the process is not trivial, typically involving fine-tuning printing parameters, and will often sacrifice spatial accuracy. Elaborate post-processing treatment of an object may also be applied, but additional materials and equipment may be necessary. Even then, success is not guaranteed. Furthermore, FDM 3D-printers lack the ability to create finely detailed parts.\u003c/p\u003e \u003cp\u003eDigital Light Processing\u003c/p\u003e \u003cp\u003eMore recently, another type of 3D-printing technique which utilizes UV-hardened resin plastics such as Selective Laser Sintering (SLS), and especially Digital Light Processing (DLP), has gained more prominence as availability increase and costs decrease. At the time of writing there is a wide selection of DLP 3D-printers which are priced as consumer electronics.\u003c/p\u003e \u003cp\u003eThe process of object formation using UV-hardened resin differs from FDM printing techniques. First, liquid UV-hardened resin is poured into a vat with a transparent film bottom. The vat is placed on top of a UV light source with LCD panel. During printing, a metal build plate is dropped into the vat, leaving only a thin layer between the bottom of the vat and the build plate. A pattern is shown through the LCD panel, exposing UV light to the thin layer or liquid resin, and curing it. The cured resin sticks onto the build plate and is then lifted from the bottom of the vat. After some time, the build plate lowers an appropriate amount again, leaving only a thin layer of space between the object and the bottom of the vat and the process iterates.\u003c/p\u003e \u003cp\u003eDLP printing technology is far superior in recreating details in parts than traditional FDM printing technology can achieve, and has been previously used to create phantoms for measuring dimensional accuracy in MRI scans\u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e,\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. DLP\u0026rsquo;s ability to recreate details has been shown to be suitable in printing dental models demanding a high degree of accuracy\u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e,\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e. Objects created by curing resin in such fashion is also inherently liquid tight\u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e,\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. To save on material costs, objects are typically hollowed out, leaving only the outer shell and perhaps some structural supports in the middle. Unhardened resin may get trapped inside during the printing process; hence drainage holes are inserted on the part towards the bottom of the build plate for the liquid resin to drain out into the vat during printing. However, if this is not done, liquid resin will remain trapped inside, which will be visible in MR images. We take advantage of this phenomenon, together with DLP\u0026rsquo;s high dimensional accuracy and ability to recreate fine details, to create objects that are inherently visible in MRI scans with low spatial tolerances cheaply and effectively.\u003c/p\u003e \u003cp\u003eMR-guided Biopsy\u003c/p\u003e \u003cp\u003eOne such application for this approach is to manufacture a MR-visible grid system for MR guided breast biopsies. During MR guided biopsies, MR images are taken of a patient\u0026rsquo;s breasts with a dedicated MR breast coil with a spatial localization system towards the side of the breast of interest. First, MRI scans are used to locate a suitable region to extract tissue samples in the breast, the localization system is then used to guide the biopsy needle toward the region of interest as on the MRI scans. This localization system is typically in the form of a grid made of hard plastic. Since the grid itself is MR-invisible, the grid must be pressed tight to make an imprint on the skin. This is not always possible as moving the grid on a rail system has limits, and since breast tissue is not infinitely deformable, the corresponding location of a target region might not be possible to obtain imprints on.\u003c/p\u003e \u003cp\u003eThis poses a challenge when trying to correlate the region of interest for the biopsy with the spatial guides during the procedure, which may result in physicians cancelling the procedure due to lack of confidence. This is not ideal since MR guided biopsies are performed only as necessary when all other methods of diagnostics is deemed unsuitable\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePurpose\u003c/p\u003e \u003cp\u003eHere we design, manufacture, and evaluate the feasibility of using DLP 3D-printing technology to produce an equivalent localization grid for MR guided biopsies that is inherently visible in MRI scans to facilitate the localization process between a target region and spatial guides for the biopsy entry point.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis work was supported by the Swedish General Medical Fund under Grant FOUI-973889.\u003c/p\u003e\n\u003ch2\u003ePart Design\u003c/h2\u003e\n\u003cp\u003eUsing 3D CAD software (Onshape, www.onshape.com), a model of the MR biopsy grid with the exact grid dimensions was created. The model is designed to fit inside the existing grid as an insert. The model then expanded 1.4mm in all directions to act as an outer hardened shell to contain liquid resin (Fig. 1).\u003c/p\u003e\n\u003ch2\u003eSlicing\u003c/h2\u003e\n\u003cp\u003eSlicer software is used to convert a 3D-model into a format which 3D-printers operate on. Anycubic\u0026rsquo;s own proprietary slicer software Photon Workshop (V.2.1.24) was used since it is guaranteed to be compatible with our 3D-printer. Most slicer software for DLP printers have similar features to prepare a model for printing. These features include hollowing out a model to save on printing costs, and correspondingly, have a feature to insert holes into the model at any given location for the unhardened resin within the model to leak out during/after printing. Here we do not wish for the unhardened resin to leak out, and hence will not insert any holes into the model, but we do wish to \u0026ldquo;hollow\u0026rdquo; out the model, creating a wall 1.4mm thick (Fig 2A).\u003c/p\u003e\n\u003cp\u003eSupport generation is also another crucial step in preparing the design for 3D-printing which is also typically handled by the slicer software. In the final printing protocol we established, the model was placed slightly at an angle (30 degrees), and above (7mm) the build plate, as this is the most robust way of printing the part (see Results). Photon Workshop\u0026rsquo;s automatic support generator was used to generate necessary support to build the part as specified (Fig. 1D).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDetailed slicer parameters including support generation parameters for the final object are found in (Table I).\u003c/p\u003e\n\u003ch2\u003e3D-printing\u003c/h2\u003e\n\u003cp\u003eA Photon Mono (Anycubic, https://www.anycubic.com/) was used to perform 3D-printing. A black tough (\u0026ldquo;ABS-like\u0026rdquo;) resin (Primacreator, article number 24592) was used for the final object. Different resin types were also used during testing, such as \u0026ldquo;standard\u0026rdquo; resins in different colors (grey PV-RESIN-B405-0500-N and transparent PV-RESIN-B405-0500-CL) and water washable resin (PV-Resin-B405-1000-SK). The curing times are slightly different for the different types and colors of resin, so depending on the color of the filament, the curing times for each layer (and \u0026ldquo;first layers\u0026rdquo;) need be adjusted accordingly. For the print to be filled with liquid resin during printing, lift height after each layer was adjusted such that the part never lifts above the level of the liquid resin still in the vat. This may require manually filling the vat with fresh liquid resin in the middle of the printing process.\u003c/p\u003e\n\u003cp\u003e3D-printing is not an exact science and requires iterative improvement to achieve the desired results. Multiple prototypes were manufactured with various changes in design, printing parameters, and resins to achieve a robust printing process. The total print time depends on various printing parameters. Using parameters used for the final object (Table I), the total print time is approximately 6 hours and 14 minutes.\u003c/p\u003e\n\u003ch2\u003ePost-production\u003c/h2\u003e\n\u003cp\u003eResidue liquid resin remains on the surface after the print is completed, so the part still needs to be handled with caution (Fig 2E). The object was removed from the print bed and the supports removed by hand in an isopropanol solution (40%) bath while wearing protective equipment. It was then further cured outdoors under the sun (summertime) for approximately 15-20 minutes. When sunlight is not easily accessible, UV light can also be used, including dedicated \u0026ldquo;washing and curing\u0026rdquo; equipment offered by different DLP 3D-printer manufacturers.\u003c/p\u003e\n\u003ch2\u003eMRI Scanning\u003c/h2\u003e\n\u003cp\u003eThe finished part was then fitted onto the existing grid (Fig. 3A, B) and scanned with breast phantoms to assess visibility of the grid in MRI images. Test scanning was performed on a GE Signa Premiere 3T MRI Scanner (Milwaukee, USA) with a 16-channel breast coil capable of MR-guided biopsy procedures (NeoCoil), with one lateral side of the coil replaced with the grid setup as standard MR-guided biopsy protocol (Fig. 3C). Both T1- and T2-weighted MRI sequences from our MR biopsy protocol used at Karolinska University Hospital were used to assess grid visibility in typical MRI scans.\u003c/p\u003e\n\u003cp\u003eThe T1-weighted sequence is an axial 3D spoiled gradient echo with a TE=1.7ms and TR=4.1ms, 340mm FOV with 360x360 in matrix size and a slice thickness of 0.7mm. The T2-weighted sequence is a 2D axial fast spin-echo, FA=111, TE=102, TR=4601, FOV=350mm, matrix size=320x320, and 3mm slice thickness.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eSince the designed part has many large flat surfaces, one would intuitively use one of such faces as the surface to adhere to the print surface (Fig. 2B). Experience shows that this makes the printing process more prone to failure (Fig. 2C) and the printing process is more robust when printing large flat surfaces at an angle (such that large surfaces are not printed at any single layer).\u003c/p\u003e\n\u003cp\u003eThe finished part should look and feel try to the touch before handling using bare hands. The UV hardened outer shell is capable of fully enclosing liquid resin inside without leakage unless cracks appear on the outer shell (see Discussion). This is visible for the prototype manufactured in transparent clear resin, made specially for investigating the degree of liquid resin inside the part (see supplementary materials). The liquid inside the produced grid object is shown to be clearly hyperintense on both T1 and T2-weighted MRI scans (Fig. 4).\u003c/p\u003e\n\u003cp\u003eTuning of printing parameters was needed to produce a filled object. Lowering the \u0026ldquo;Z-lift\u0026rdquo; length such that the lower edge of the unfinished print never lifts above the level of liquid resin remaining in the vat aids to retain liquid resin inside the part during print through vacuum suspension. Depending on size and shape of the vat, manually filling the vat with fresh liquid resin during print might be necessary. Figure 5 shows the difference between a grid fully filled with liquid resin versus one that is only partially filled with resin due to suboptimal printing parameters.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eSome downsides of the techniques are not only derived from the inherent downsides of the 3D-printing technique, but also from our unusual application of the technology. Any object produced in this manner must not only be 3D-printable in general, but the design must also allow for the MR visible sections to be fully enclosed by a hardened outer shell which lays additional restrictions during design. Experience indicates that at least 1.4mm thick is recommended for the part to be able to withstand normal handling.\u003c/p\u003e\n\u003cp\u003eSince this method of production replies on liquid retention, the method of printing large objects in parts and then assemble them in post-processing in applicable in this case, hence the overall size of the object is restricted to the build volume the 3D-printer. Depending on the model of the 3D-printer, this may be a considerable restriction. Although more expensive 3d printers capable of producing larger parts do exist, they are also considerably more expensive to acquire and run. In addition, filling a part with liquid resin adds significant production costs to the part compared to draining it.\u003c/p\u003e\n\u003cp\u003eDue to the brittle nature of the conventional UV-hardened resin, it would not be suitable to print such parts using the material. Fractures eventually appear on parts printing using \u0026ldquo;standard\u0026rdquo; resins (Fig. 6) after some time ranging from a couple of days to a year. The fractures eventually expand and deepen resulting in liquid resin leakages. The exact cause of this is currently unknown and is yet to be investigated. A tougher material such as \u0026ldquo;ABS\u0026rdquo;-like, or engineering resin, which are both harder, and more malleable in their cured state is preferred since parts printed using these resins has yet to show fractures in their outer shells, even after more than a year from initial printing.\u003c/p\u003e\n\u003cp\u003eAs the liquid resin will harden under UV-light, it is recommended that the parts are stored in a dark space with minimal/no UV light penetration. While transparent resins will cause more UV shine-through and hence will cure more quickly, darker opaque colored resins may retain liquid inside for longer. Systematic investigation of MRI visibility over time for different resin colors is yet to be done. But preliminary experiments show that independent of resin color, the produced parts will eventually fully harden, and as such no parts produced in this manner will be permanently MR-visible.\u003c/p\u003e\n\u003cp\u003eThis production process can be used to cheaply manufacture various devices designed to be inherently visible in MRI scans, such as phantoms and markers. Due to the great spatial accuracy of the 3D printing technology, the produced parts will not only be inherently liquid tight, but also dimensionally accurate for quality assessment applications.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eUsing relatively cheap and simple DLP 3D-printing techniques, we are able to construct dimensionally accurate parts that are inherently visible in typical MRI scans. The produced part is designed specifically to aid in spatial localization of tumors in MR-guided biopsy procedures, greatly simplifying the procedure and enhance confidence for personnel in the process.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthorship confirmation/contribution statement\u003c/h2\u003e\n\u003cp\u003eThe sole author is the only contributor to the study and is fully responsible for all aspects of the study.\u003c/p\u003e\n\u003ch2\u003eAuthor\u0026rsquo;s Disclosure\u003c/h2\u003e\n\u003cp\u003eThe author does not have any conflicts of interest to declare.\u003c/p\u003e\n\u003ch2\u003eFunding\u003c/h2\u003e\n\u003cp\u003eThis work was supported by the Swedish General Medical Fund under Grant FOUI-973889.\u003c/p\u003e\n\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\n\u003cp\u003eY.W devised, and performed, and presented all aspects of this study.\u003c/p\u003e\n\u003ch2\u003eAcknowledgement\u003c/h2\u003e\n\u003cp\u003eThe author would like to acknowledge Tomas Jonsson for facilitating the initial purchase of equipment.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eKrkobabić M, Medarević D, Pe\u0026scaron;ić N, Vasiljević D, Ivković B, Ibrić S. Digital Light Processing (DLP) 3D Printing of Atomoxetine Hydrochloride Tablets Using Photoreactive Suspensions. \u003cem\u003ePharmaceutics\u003c/em\u003e. 2020;12(9):833. doi:10.3390/pharmaceutics12090833\u003c/li\u003e\n\u003cli\u003eNugroho WT, Dong Y, Pramanik A. Dimensional accuracy and surface finish of 3D printed polyurethane (PU) dog-bone samples optimally manufactured by fused deposition modelling (FDM). \u003cem\u003eRapid Prototyp J\u003c/em\u003e. 2022;28(9):1779-1795. doi:10.1108/RPJ-12-2021-0328\u003c/li\u003e\n\u003cli\u003eRamachandran P, Noble C, Langton C, et al. A 3D printed phantom to assess MRI geometric distortion. \u003cem\u003eBiomed Phys Eng EXPRESS\u003c/em\u003e. 2021;7(3):035004. doi:10.1088/2057-1976/abeb7e\u003c/li\u003e\n\u003cli\u003eRai R, Wang YF, Manton D, Dong B, Deshpande S, Liney GP. Development of multi-purpose 3D printed phantoms for MRI. \u003cem\u003ePhys Med Biol\u003c/em\u003e. 2019;64(7):075010. doi:10.1088/1361-6560/ab0b49\u003c/li\u003e\n\u003cli\u003eTsolakis IA, Papaioannou W, Papadopoulou E, Dalampira M, Tsolakis AI. Comparison in Terms of Accuracy between DLP and LCD Printing Technology for Dental Model Printing. \u003cem\u003eDent J\u003c/em\u003e. 2022;10(10):181. doi:10.3390/dj10100181\u003c/li\u003e\n\u003cli\u003ePark JM, Jeon J, Koak JY, Kim SK, Heo SJ. Dimensional accuracy and surface characteristics of 3D-printed dental casts. \u003cem\u003eJ Prosthet Dent\u003c/em\u003e. 2021;126(3):427-437. doi:10.1016/j.prosdent.2020.07.008\u003c/li\u003e\n\u003cli\u003eQiu J, Hou K, Dyer BA, et al. Constructing Customized Multimodal Phantoms Through 3D Printing: A Preliminary Evaluation. \u003cem\u003eFront Phys\u003c/em\u003e. 2021;9. Accessed October 2, 2023. https://www.frontiersin.org/articles/10.3389/fphy.2021.605630\u003c/li\u003e\n\u003cli\u003eBieniosek MF, Lee BJ, Levin CS. Technical Note: Characterization of custom 3D printed multimodality imaging phantoms. \u003cem\u003eMed Phys\u003c/em\u003e. 2015;42(10):5913-5918. doi:10.1118/1.4930803\u003c/li\u003e\n\u003cli\u003eViehweg P, Heinig A, Amaya B, Alberich T, Laniado M, Heywang-K\u0026ouml;brunner SH. MR-guided interventional breast procedures considering vacuum biopsy in particular. \u003cem\u003eEur J Radiol\u003c/em\u003e. 2002;42(1):32-39. doi:10.1016/s0720-048x(01)00479-x\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Table","content":"\u003cp\u003eTable I: Slicing, automatic support generation, and printing parameters.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003ctable id=\"Taba\" border=\"1\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSetting Group\u003c/div\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eParameter Label\u003c/div\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eParameter Value\u003c/div\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSlice Settings\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eLayer Thickness (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e0.05\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eExpose Time (s)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e10\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eOff Time (Between exposure)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e0.5\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eBottom Exposure Time\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e40\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eBottom Layers\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e10\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eZ Lift Distance (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSupport Shape Settings\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eTop\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eContact Shape\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eDefault\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eContact Depth (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e0.4\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eContact Diameter\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e0.8\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eShape\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eCone\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eDiameter (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e1.2\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eLength (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e2.0\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eAngle (degrees)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e72\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eMid\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eShape\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eCylinder\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eDiameter (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e1.2\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eBottom\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003ePlatform Touch Shape\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSkate\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eTouch Diameter (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e12.0\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eThickness (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e1.00\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eContact Shape\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eDefault\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eContact Diameter (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e0.60\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eContact Depth (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e0.20\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eRaft\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eShape\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eDefault\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eRaft Thickness (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e2.70\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eRaft Inner Thickness (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e1.00\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eRaft Angle\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e45\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSupport Generation Settings\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eHollow Mesh\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eNo\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eType\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eVertical\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eAutoSupportAngle\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e70\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSupport Density (%)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e70\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003eSupport Min Length (mm)\u003c/div\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cdiv class=\"SimplePara\"\u003e3.00\u003c/div\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"3d-printing-in-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tdpm","sideBox":"Learn more about [3D Printing in Medicine](https://threedmedprint.biomedcentral.com/)","snPcode":"41205","submissionUrl":"https://submission.nature.com/new-submission/41205/3","title":"3D Printing in Medicine","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Rapid prototyping, medical devices, phantoms, biopsy, radiology","lastPublishedDoi":"10.21203/rs.3.rs-4234954/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4234954/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eHard plastics are typically invisible in MRI images, while fluids are not. Objects manufactured using traditional Fuse Deposition Modelling (FDM) 3D-printing techniques are prone to leakage. 3D-printers which use UV-hardened resin to form objects possess a trait that is considered a technical inconvenience: Objects created using these techniques are inherently liquid-tight, and hollow parts require addition of drainage holes for uncured liquid resin to escape. If this is not done liquid resin will remain inside the object, which in some cases is the desired outcome. Digital Light Processing (DLP) is an affordable 3D-printing technique using UV-hardened resin. The technique also possesses superior dimensional accuracy and the ability to recreate fine details.\u003c/p\u003e\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eWe devised a method to produce an inherently MR-visible accessory using DLP technology with low dimensional tolerance to facilitate MR-guided breast biopsies.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eBy hollowing out the object without adding drainage holes and tuning printing parameters such as z-lift distance to retain as much uncured liquid resin inside as possible, objects that are inherently visible in MRI scans can be created without further treatment.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eObjects created through our method are simple and cheap to recreate, have minimal manufacturing steps, and are shown to be dimensionally exact and inherently MRI visible to be directly used in various applications without further treatment.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eWhile this method may not always be suitable, we demonstrate that this process is viable in creating highly accurate objects that are inherently visible in MRI scans using equipment that is easy to obtain and trivial in cost.\u003c/p\u003e","manuscriptTitle":"3D-printing Inherently MR-visible Accessories in Aiding MR-Guided Biopsies","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-04-19 18:33:05","doi":"10.21203/rs.3.rs-4234954/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-06-05T05:25:45+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-31T14:42:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"283639866028976765369409213238665004490","date":"2024-05-31T13:30:07+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-30T20:31:34+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"279237181902820598193135583257078395335","date":"2024-05-30T20:29:37+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-05-02T23:53:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"93258b8d-9c50-45db-8256-fe2920ca90d1","date":"2024-04-20T11:06:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-04-15T04:58:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-04-11T08:32:32+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-04-11T08:32:31+00:00","index":"","fulltext":""},{"type":"submitted","content":"3D Printing in Medicine","date":"2024-04-08T08:14:15+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"3d-printing-in-medicine","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"tdpm","sideBox":"Learn more about [3D Printing in Medicine](https://threedmedprint.biomedcentral.com/)","snPcode":"41205","submissionUrl":"https://submission.nature.com/new-submission/41205/3","title":"3D Printing in Medicine","twitterHandle":"@BioMedCentral","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"BMC/SO AJ","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"21f73afd-77f1-4395-aa7e-a876fb9e9b81","owner":[],"postedDate":"April 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-08-12T16:00:49+00:00","versionOfRecord":{"articleIdentity":"rs-4234954","link":"https://doi.org/10.1186/s41205-024-00227-w","journal":{"identity":"3d-printing-in-medicine","isVorOnly":false,"title":"3D Printing in Medicine"},"publishedOn":"2024-08-05 15:57:14","publishedOnDateReadable":"August 5th, 2024"},"versionCreatedAt":"2024-04-19 18:33:05","video":"","vorDoi":"10.1186/s41205-024-00227-w","vorDoiUrl":"https://doi.org/10.1186/s41205-024-00227-w","workflowStages":[]},"version":"v1","identity":"rs-4234954","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4234954","identity":"rs-4234954","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}