Homologous 111In-radiolabeled platelet survival and sequestration exploration for refractory immunologic thrombocytopenic purpura in children: a strategy to avoid unnecessary splenectomy

Homologous 111In-radiolabeled platelet survival and sequestration exploration for refractory immunologic thrombocytopenic purpura in children: a strategy to avoid unnecessary splenectomy | 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 Research Article Homologous 111In-radiolabeled platelet survival and sequestration exploration for refractory immunologic thrombocytopenic purpura in children: a strategy to avoid unnecessary splenectomy Julien Dubois, Florentin Kucharczak, Léa De Neef, Virginie Kouyoumdjian, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4017056/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Purpose Immunologic thrombocytopenic purpura (ITP) is a condition that affects 4 to 18 per 100 000 children every year. In most cases, spontaneous remission occurs, but splenectomy can be proposed to diminish excessive destruction of platelets when ITP is refractory. Exploring the site of platelet sequestration may help to better predict potential poor responders to splenectomy if no spleen sequestration is highlighted. The radiolabeled platelet sequestration test may be an option but can be difficult to perform in children with very few platelets. Methods A twelve-year-old boy suffering from chronical ITP was referred to evaluate platelet survival and sequestration, to discuss splenectomy. The patient was refractory to therapy and his platelet count consistently remained below 10 G.L-1. An exceptional procedure was set up to use homologous platelets to perform a radiolabeled platelet survival and sequestration test. A radiolabeled autologous platelet exam was carried five months later to confirm the test. Results Significantly reduced platelet lifespan and half-life was observed for both techniques. The splenic and hepatic ratio were below 1.2 at all time points, meaning that there was no organ sequestration. The fact that we confirmed our test by two different methods allowed us to reject the indication for splenectomy in this child. Strict intravascular destruction has been confirmed. Conclusions 111In-radiolabeled homologous platelets were used to perform the examination and confirmed the results obtained with autologous platelets. Homologous platelet scintigraphy could help clinicians to choose splenectomy as a treatment option for ITP in children with very low platelet count. Work must be done to promote its use. Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction 111 In-radiolabeled platelet scintigraphy has demonstrated its utility in the study of platelet survival, enabling the investigation of the mechanism behind thrombocytopenia, as well as in the search for a potential site of splenic sequestration [ 1 , 2 ]. Unfortunately, since patients' own platelets serve as a marker in this investigation (autologous platelets), it can only be routinely conducted on individuals with an adequate platelet count. A minimum number of platelets is required for the test to be carried out correctly. When platelet levels are insufficient, it becomes necessary to carry out this examination using homologous platelets (from donors). Radiolabeling homologous platelets shouldn't be problematic, in theory, especially because platelet isolation procedures are not required, and radiolabeling techniques are efficient. Nevertheless, procedures must be adapted to thrombocytes conditioning, i.e., formulation and packaging, and homologous platelet administration must follow good transfusion practices. Homologous radiolabeled platelets appear a safe and efficient procedure in a very low platelets count situation and had been performed for a long time [ 3 , 4 ]. Its use in infants and children remain uncommon and is essentially for rare disease or chronical thrombopenia [ 5 , 6 ]. Isolation of platelets from whole blood is not needed considering its nature. This make the specific labeling much easier as the lipophilic complex used is not platelet specific [ 7 ]. Neither it is necessary to take a sample from the patient which can sometimes be difficult in children and infants. Here, we discuss a child's case in which we conducted a radiolabeled homologous platelet exam, validated by a subsequent radiolabeled autologous platelet exam which enabled clinicians to avoid splenectomy. Material and methods A twelve-year-old boy suffering from chronical immunologic thrombocytopenic purpura (ITP) was referred to the nuclear medicine department of Montpellier University Hospital to evaluate platelet survival and sequestration, to discuss splenectomy. The patient was refractory to therapy (corticosteroids, immunosuppressive agents, and immunoglobulins) and his platelet count consistently remained below 10 G.L − 1 . Below this threshold, the number of platelets required for correct radiolabeling cannot be obtained with a sample volume that is tolerable for his morphology. Two autologous platelets tests in two different hospitals both failed due to low platelet counts leading us to perform a scintigraphy exam using homologous platelets. To confirm our results, radiolabeled autologous platelet exam was performed remotely thereafter, with a platelet count around 30 G.L − 1 after a thrombopoietin receptor-agonists (TPO-RA) treatment intensification. A summary of the patient's history is shown in Fig. 1 . For information, he was diagnosed with ITP in august 2020. He has moderate hemorrhagic syndrome, with an impact on his quality of life, and a psychological impact on him and his parents. Anti-platelet antibodies search reveals anti-glycoprotein IIb-IIIa and Ib-IX autoantibodies. Our patient has A RH1 (D+) blood group phenotype, had anti-HLA class I antibodies, and no irregular antibodies. The radiolabeling process follows the French good preparation practices [ 8 ]. Platelets are isolated from blood after sampling for autologous process, or concentrated for homologous process into a pellet. [ 111 In]In-oxinate solution is used for platelet radiolabeling. [ 111 In]In 3+ has good radiopharmaceutical characteristics such as medium gamma energies (171–245 keV), and a radioactive period of 2.8 days that allows a several days monitoring [ 9 ]. As a metal cation in the + 3 oxidation state, indium(III) oxine can easily coordinate with species that are abundant in electrons. The present radiolabeling process is simple, not specific and has been validated long time ago: after buffering to pH 6, the complex [ 111 In]In-oxinate can pass through cell membranes. Then it dissociates and [ 111 In]In 3+ forms a bond with intracellular proteins [ 10 , 7 ]. Platelet concentrate (PC) used in homologous method must be from apheresis, irradiated and be strictly ABO/RH1 grouped and HLA compatible. Donor’s platelets were collected, processed by filtration, quantified, and tagged the day before radiolabeling by the French blood establishment (EFS). Conformity and security controls upon receipt of the PC and pre-transfusion controls are carried out by the hemovigilance department. The use of PC for this technique is subject to an authorization issued by the French national agency for the safety of medicines and health products (ANSM). This agency recommends that the PC used be untreated with amotosalen that could impact viability results [ 11 ]. Radiolabeling tests were carried out beforehand by the radiopharmacists to validate the process and set up a procedure. Good transfusion practices were followed, and an infusion set with a 200 µm filter was used to block any small aggregates that may be present in the PC as required for classic platelet transfusion [ 12 ]. Radiolabeled platelets were injected by a catheter at the elbow crease, 15 MBq and 6 MBq, for homologous and autologous radiolabeled platelet procedures respectively. We halved the dose for the second exam to reduce the child's radiation exposure, given the good results of the first exam. Clinical parameters of the patient were continuously monitored. This patient benefits a particular hemovigilance and pharmacovigilance follow-up for any adverse event. The same data collection and data analysis procedures were carried out for radiolabeled platelet examinations in both homologous and autologous settings. Blood samplings were performed from the contralateral arm up at 0.5, 1, 3, 24, 48, 72 hours post-injection (additional 96 hours point for autologous exam). Radioactivity measures were performed with a gamma counter (Wizard 1480®, Perkin Elmer) to evaluate platelet lifespan. The platelet half-life was determined graphically. Single-photon emission computerized tomography (SPECT) acquisitions of the thoraco-abdominal region were performed 0.75, 1, 4, 24, 48, 72 hours post-injection using a dual-head NM/CT 870-DR gamma-camera equipped with middle-energy-general-purpose parallel-hole collimators (GE Healthcare, Tirat Carmel, Israel) (additional 96 hours image for autologous exam). Anterior and posterior images were acquired simultaneously and geometrically averaged. Platelet sequestration was determined from a radioactivity count in a region of interest (ROI) traced around an organ, normalized by the activity measured in that organ 45 minutes after administration of labelled platelets. Late sequestration was defined as splenic or hepatic if the ratio exceeded 1.2 [ 13 ]. Results The activity measured in the blood samples decreased exponentially between 30 minutes and 72 hours. Significantly reduced homologous and autologous platelet lifespan was observed in the two exams. Homologous and autologous platelet half-life was calculated after exponential fit at 1.80 and 4.70 hours respectively (Fig. 2 ). The splenic and hepatic ratios remained below 1.2 at all time points for both homologous and autologous test. Only splenic uptake ratio at 24h appears at the level of the upper threshold i.e., 1.2, for autologous test. Other ratios were under 1.2 (Fig. 3 ). Visually, the images obtained with the two techniques were comparable. A lower count rate (and higher background noise) was noted for the examination with autologous platelets. This goes hand in hand with a lower rate of marked platelets in the case of autologous exam. Figure 4 shows imaging results of homologous and autologous 111 In-radiolabeled platelet injection right after injection and three days after. Discussion We conducted a platelet lifespan evaluation and explored a potential sequestration site in a young patient with severe thrombocytopenia associated with an ITP therapeutic escape. 111 In-radiolabeled homologous platelets were used to perform the examination with a platelet count of 9 G.L − 1 . These explorations are known to be effective predictors of a good response to splenectomy in case of isolated splenic sequestration. Splenectomy can be avoided if no sequestration, mixed or hepatic sequestration are shown [ 13 – 16 ]. There is insufficient evidence to support strong management recommendations on the management of ITP. Splenectomy comes in second-line therapy after corticosteroids, TPO-RA and Rituximab, and it is generally delayed for at least 1 year after diagnosis. Ancient and actual international recommendations do not mention platelet survival and sequestration examination to undergo splenectomy in ITP [ 17 – 19 ]. Recent studies demonstrate that radiolabeled platelet exploration is useful to guide treatment [ 20 , 21 ]. In children, it is advisable to avoid unnecessary splenectomies, as it is important for them to remain protected against infections caused by particularly encapsulated bacteria, without antibiotic prophylaxis or vaccination, especially as it is known that many children are likely to experience spontaneous remission of ITP [ 19 ]. In our case, avoiding splenectomy that certainly would not improve the ITP severity was important both physically and psychologically. An uncommon ITP phenomenon identified as diffuse endovascular destruction of immunological cause was then suspected for this child, which enabled to avoid an unnecessary splenectomy. Our patient was treated by TPO-RA and the possibility of interference with the exam was raised. A study shows that TPO-RA may overcompensate platelet destruction in ITP and may reduce platelet destruction rate [ 22 ]. Another more recent study suggests that TPO-RA doesn’t modify either the site of platelet destruction or the platelet survival and raises the fact that the increased estimated platelet production is not sufficient to overcome the platelet destruction by the immune system [ 23 ]. As there was no difference between the results of the homologous and the autologous exams, we concluded that there was no interference from TPO-RA treatment in our case. Results of the homologous procedure has been validated remotely with a radiolabeled autologous platelets exploration which was achieved following the intensification of TPO-RA treatment. The use of homologous platelets should remain the exception, due to transfusion issues and the difficulty of supply and storage of PC. However, homologous platelet scintigraphy could help clinicians to choose splenectomy as a treatment option for ITP in children with very low platelet count. Additional, more systematic studies on larger populations are needed to confirm the indication of homologous platelet scintigraphy. Abbreviations ANSM: French national agency for the safety of medicines and health products EFS: French blood establishment ITP: immunologic thrombocytopenic purpura PC: platelet concentrate ROI: Region of interest SPECT: single-photon emission computerized tomography TPO-RA: thrombopoietin receptor-agonists Declarations Ethics approval and consent to participate This study was conducted in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. It was approved by the Montpellier university hospital’s local institutional review board under the number 2024-01-010 the 5 th February 2024. Written information was given to the patient’s parents. Consent for publication Written informed consent was obtained from the patient’s parents for publication of this study and accompanying images. Availability of data and material The datasets used and/or analysed during the current study are available from the corresponding author upon reasonable request. Competing interests The authors declare that they have no competing interests. Funding The authors declare that they have received no funding for this study. Authors' contributions JD, FK, LD, VK, GP, VT, DM, AB, and TP contributed to the study conception and design. Material preparation, data collection and analysis were performed by JD, AB, FK, and TP. The first draft of the manuscript was written by JD. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Acknowledgements We would like to thank Aurélie Conte and the French blood establishment (EFS) for their work and for allowing us to carry out the homologous test by providing the donor’s platelets. References International Committee for Standardization in Hematology. PROPOSED RECOMMENDATIONS FOR MEASUREMENT OF SERUM IRON IN HUMAN BLOOD. Br J Haematol. 1971;20:451–3. Najean Y, Dufour V, Rain JD, Toubert ME. The site of platelet destruction in thrombocytopenic purpura as a predictive index of the efficacy of splenectomy. Br J Haematol. 1991;79:271–6. Peters AM, Porter JB, Saverymuttu SH, Malik F, Zuiable A, Lavender JP, et al. The kinetics of unmatched and HLA-matched 111 In-labelled homologous platelets in recipients with chronic marrow hypoplasia and anti-platelet immunity. Br J Haematol. 1985;60:117–27. Hammersmith SM, Jacobson AF, Mankoff DA. Scintigraphy with indium-111-labeled homologous (donor) platelets in the platelet transfusion refractory bone marrow transplant patient. J Nucl Med Off Publ Soc Nucl Med. 1997;38:1135–8. Schmidt RP, Lentle BC. Hemangioma with Consumptive Coagulopathy (Kasabach-Merritt Syndrome) Detection by lndium-111 Oxine-labeled Platelets. Clin Nucl Med. 1984;9:389–91. Castle V, Coates G, Kelton JG, Andrew M. 111In-oxine platelet survivals in thrombocytopenic infants. Blood. 1987;70:652–6. Mathias CJ, Welch MJ. Radiolabeling of platelets. Semin Nucl Med. 1984;14:118–27. Bonnes pratiques de préparation [Internet]. ANSM. 2023 [cité 19 juill 2023]. Disponible sur: https://ansm.sante.fr/documents/reference/bonnes-pratiques-de-preparation . National Nuclear Data Center. Nuclear Decay Data of Indium-111 in the MIRD Format [Internet]. [cité 19 juill 2023]. Disponible sur: https://www.nndc.bnl.gov/nudat3/mird/ . Peters A, Lavender J. Platelet Kinetics with Indium-111 Platelets: Comparison with Chromium-51 Platelets. Semin Thromb Hemost. 1983;9:100–14. Snyder E, Raife T, Lin L, Cimino G, Metzel P, Rheinschmidt M, et al. Recovery and life span of 111 indium-radiolabeled platelets treated with pathogen inactivation with amotosalen HCl (S-59) and ultraviolet A light: RECOVERY AND LIFE SPAN OF PCT PLTs. Transfus (Paris). 2004;44:1732–40. ANSM. Bonnes pratiques transfusionnelles [Internet]. ANSM. 2020 [cité 19 juill 2023]. Disponible sur: https://ansm.sante.fr/documents/reference/bonnes-pratiques-transfusionnelles . Lamy T, Moisan A, Dauriac C, Ghandour C, Morice P, Le Prise PY. Splenectomy in idiopathic thrombocytopenic purpura: its correlation with the sequestration of autologous indium-111-labeled platelets. J Nucl Med Off Publ Soc Nucl Med. 1993;34:182–6. Sarpatwari A, Provan D, Erqou S, Sobnack R, David Tai FW, Newland AC. Autologous 111In-labelled platelet sequestration studies in patients with primary immune thrombocytopenia (ITP) prior to splenectomy: a report from the United Kingdom ITP Registry: 111Indium Studies Prior to Splenectomy for ITP. Br J Haematol. 2010;151:477–87. Roca M, Muñiz-Diaz E, Mora J, Romero-Zayas I, Ramón O, Roig I, et al. The scintigraphic index spleen/liver at 30 minutes predicts the success of splenectomy in persistent and chronic primary immune thrombocytopenia. Am J Hematol. 2011;86:909–13. Kazi S, Mckiddie F, Anderson J, Bagot C, Duncan C, Drummond M, et al. Autologous 111 In-labelled platelet scan as a predictor of splenectomy outcome in ITP. Br J Haematol. 2019;184:1043–5. Neunert C, Lim W, Crowther M, Cohen A, Solberg L, Crowther MA. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood. 2011;117:4190–207. D’Orazio JA, Neely J, Farhoudi N. ITP in Children: Pathophysiology and Current Treatment Approaches. J Pediatr Hematol Oncol. 2013;35:1–13. Neunert C, Terrell DR, Arnold DM, Buchanan G, Cines DB, Cooper N, et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Adv. 2019;3:3829–66. Ratnasingam S, Reid AS, Ma D, Bucki-Smith D, Gwini SM, Seneviratna L, et al. Indium‐labelled autologous platelet sequestration studies predict response to splenectomy in immune thrombocytopenia: an Australian experience. Intern Med J. 2022;52:1387–93. Durand P, Pottier V, Mesguich C, Debordeaux F, Lazaro E, Viallard J-F, et al. Utility of indium-111 platelet scintigraphy for understanding the mechanism of thrombocytopenia associated with myelodysplastic syndromes and chronic myelomonocytic leukemia. Exp Hematol Oncol. 2023;12:50. Meyer O, Herzig E, Salama A. Platelet Kinetics in Idiopathic Thrombocytopenic Purpura Patients Treated with Thrombopoietin Receptor Agonists. Transfus Med Hemotherapy. 2012;39:5–8. Mahevas M, Van Eeckhoudt S, Moulis G, Limal N, Languille L, Bierling P, et al. Autologous 111 Indium-oxinate‐labelled platelet sequestration study in patients with immune thrombocytopenia treated by thrombopoietin receptor‐agonists. Br J Haematol [Internet]. 2019. 10.1111/bjh.15890 . [cité 20 juill 2023];186. Disponible sur. https://onlinelibrary.wiley.com/doi/ . Cite Share Download PDF Status: Posted Version 1 posted 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-4017056","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":280585548,"identity":"687be6e1-9984-4d89-865e-fc25e76b8587","order_by":0,"name":"Julien 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history\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-4017056/v1/d86abbf93ee057219e660562.png"},{"id":53012335,"identity":"02003c5f-47ff-4845-8214-74a1d11bfa38","added_by":"auto","created_at":"2024-03-19 15:40:25","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":172772,"visible":true,"origin":"","legend":"\u003cp\u003eSame patient blood activity after homologous (left) and autologous (right) \u003csup\u003e111\u003c/sup\u003eIn-radiolabeled platelet injection\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-4017056/v1/45a467597d61639286e7fe92.png"},{"id":53012333,"identity":"9e98cb40-cb24-4f1b-a0c0-2452f5239b9f","added_by":"auto","created_at":"2024-03-19 15:40:25","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":84712,"visible":true,"origin":"","legend":"\u003cp\u003eSame patient spleen and liver ratios after homologous (left) and autologous (right) \u003csup\u003e111\u003c/sup\u003eIn-radiolabeled platelet injection (spleen at t / (spleen t=0) and liver at t / (liver t=0))\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-4017056/v1/753112b4a259a71934212048.png"},{"id":53012334,"identity":"f7c8c6b5-cf8e-4f1f-aa64-7b7e0edbfd86","added_by":"auto","created_at":"2024-03-19 15:40:25","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":638124,"visible":true,"origin":"","legend":"\u003cp\u003eSame patient acquisition after homologous (A) and autologous (B) \u003csup\u003e111\u003c/sup\u003eIn-radiolabeled platelet injection. Top image: t=0.5h geometrical mean, bottom images: t=72h geometrical mean (decay uncorrected on the left and decay corrected on the right).\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-4017056/v1/a3b57185d09cc870e8ab234b.png"},{"id":54152132,"identity":"4712dddf-66ab-4cb8-ae6a-65248f606fc5","added_by":"auto","created_at":"2024-04-05 10:56:05","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":621115,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4017056/v1/aa9d10c9-ab1e-4a24-bbaa-f0bab813bbb2.pdf"}],"financialInterests":"","formattedTitle":"Homologous 111In-radiolabeled platelet survival and sequestration exploration for refractory immunologic thrombocytopenic purpura in children: a strategy to avoid unnecessary splenectomy","fulltext":[{"header":"Introduction","content":"\u003cp\u003e \u003csup\u003e111\u003c/sup\u003eIn-radiolabeled platelet scintigraphy has demonstrated its utility in the study of platelet survival, enabling the investigation of the mechanism behind thrombocytopenia, as well as in the search for a potential site of splenic sequestration [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Unfortunately, since patients' own platelets serve as a marker in this investigation (autologous platelets), it can only be routinely conducted on individuals with an adequate platelet count. A minimum number of platelets is required for the test to be carried out correctly. When platelet levels are insufficient, it becomes necessary to carry out this examination using homologous platelets (from donors).\u003c/p\u003e \u003cp\u003eRadiolabeling homologous platelets shouldn't be problematic, in theory, especially because platelet isolation procedures are not required, and radiolabeling techniques are efficient. Nevertheless, procedures must be adapted to thrombocytes conditioning, i.e., formulation and packaging, and homologous platelet administration must follow good transfusion practices. Homologous radiolabeled platelets appear a safe and efficient procedure in a very low platelets count situation and had been performed for a long time [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Its use in infants and children remain uncommon and is essentially for rare disease or chronical thrombopenia [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Isolation of platelets from whole blood is not needed considering its nature. This make the specific labeling much easier as the lipophilic complex used is not platelet specific [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Neither it is necessary to take a sample from the patient which can sometimes be difficult in children and infants.\u003c/p\u003e \u003cp\u003eHere, we discuss a child's case in which we conducted a radiolabeled homologous platelet exam, validated by a subsequent radiolabeled autologous platelet exam which enabled clinicians to avoid splenectomy.\u003c/p\u003e"},{"header":"Material and methods","content":"\u003cp\u003eA twelve-year-old boy suffering from chronical immunologic thrombocytopenic purpura (ITP) was referred to the nuclear medicine department of Montpellier University Hospital to evaluate platelet survival and sequestration, to discuss splenectomy. The patient was refractory to therapy (corticosteroids, immunosuppressive agents, and immunoglobulins) and his platelet count consistently remained below 10 G.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Below this threshold, the number of platelets required for correct radiolabeling cannot be obtained with a sample volume that is tolerable for his morphology. Two autologous platelets tests in two different hospitals both failed due to low platelet counts leading us to perform a scintigraphy exam using homologous platelets. To confirm our results, radiolabeled autologous platelet exam was performed remotely thereafter, with a platelet count around 30 G.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e after a thrombopoietin receptor-agonists (TPO-RA) treatment intensification. A summary of the patient's history is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. For information, he was diagnosed with ITP in august 2020. He has moderate hemorrhagic syndrome, with an impact on his quality of life, and a psychological impact on him and his parents. Anti-platelet antibodies search reveals anti-glycoprotein IIb-IIIa and Ib-IX autoantibodies. Our patient has A RH1 (D+) blood group phenotype, had anti-HLA class I antibodies, and no irregular antibodies.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe radiolabeling process follows the French good preparation practices [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Platelets are isolated from blood after sampling for autologous process, or concentrated for homologous process into a pellet. [\u003csup\u003e111\u003c/sup\u003eIn]In-oxinate solution is used for platelet radiolabeling. [\u003csup\u003e111\u003c/sup\u003eIn]In\u003csup\u003e3+\u003c/sup\u003e has good radiopharmaceutical characteristics such as medium gamma energies (171\u0026ndash;245 keV), and a radioactive period of 2.8 days that allows a several days monitoring [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. As a metal cation in the +\u0026thinsp;3 oxidation state, indium(III) oxine can easily coordinate with species that are abundant in electrons. The present radiolabeling process is simple, not specific and has been validated long time ago: after buffering to pH 6, the complex [\u003csup\u003e111\u003c/sup\u003eIn]In-oxinate can pass through cell membranes. Then it dissociates and [\u003csup\u003e111\u003c/sup\u003eIn]In\u003csup\u003e3+\u003c/sup\u003e forms a bond with intracellular proteins [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePlatelet concentrate (PC) used in homologous method must be from apheresis, irradiated and be strictly ABO/RH1 grouped and HLA compatible. Donor\u0026rsquo;s platelets were collected, processed by filtration, quantified, and tagged the day before radiolabeling by the French blood establishment (EFS). Conformity and security controls upon receipt of the PC and pre-transfusion controls are carried out by the hemovigilance department. The use of PC for this technique is subject to an authorization issued by the French national agency for the safety of medicines and health products (ANSM). This agency recommends that the PC used be untreated with amotosalen that could impact viability results [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Radiolabeling tests were carried out beforehand by the radiopharmacists to validate the process and set up a procedure. Good transfusion practices were followed, and an infusion set with a 200 \u0026micro;m filter was used to block any small aggregates that may be present in the PC as required for classic platelet transfusion [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eRadiolabeled platelets were injected by a catheter at the elbow crease, 15 MBq and 6 MBq, for homologous and autologous radiolabeled platelet procedures respectively. We halved the dose for the second exam to reduce the child's radiation exposure, given the good results of the first exam. Clinical parameters of the patient were continuously monitored. This patient benefits a particular hemovigilance and pharmacovigilance follow-up for any adverse event.\u003c/p\u003e \u003cp\u003eThe same data collection and data analysis procedures were carried out for radiolabeled platelet examinations in both homologous and autologous settings. Blood samplings were performed from the contralateral arm up at 0.5, 1, 3, 24, 48, 72 hours post-injection (additional 96 hours point for autologous exam). Radioactivity measures were performed with a gamma counter (Wizard 1480\u0026reg;, Perkin Elmer) to evaluate platelet lifespan. The platelet half-life was determined graphically. Single-photon emission computerized tomography (SPECT) acquisitions of the thoraco-abdominal region were performed 0.75, 1, 4, 24, 48, 72 hours post-injection using a dual-head NM/CT 870-DR gamma-camera equipped with middle-energy-general-purpose parallel-hole collimators (GE Healthcare, Tirat Carmel, Israel) (additional 96 hours image for autologous exam). Anterior and posterior images were acquired simultaneously and geometrically averaged. Platelet sequestration was determined from a radioactivity count in a region of interest (ROI) traced around an organ, normalized by the activity measured in that organ 45 minutes after administration of labelled platelets. Late sequestration was defined as splenic or hepatic if the ratio exceeded 1.2 [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eThe activity measured in the blood samples decreased exponentially between 30 minutes and 72 hours. Significantly reduced homologous and autologous platelet lifespan was observed in the two exams. Homologous and autologous platelet half-life was calculated after exponential fit at 1.80 and 4.70 hours respectively (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eThe splenic and hepatic ratios remained below 1.2 at all time points for both homologous and autologous test. Only splenic uptake ratio at 24h appears at the level of the upper threshold i.e., 1.2, for autologous test. Other ratios were under 1.2 (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eVisually, the images obtained with the two techniques were comparable. A lower count rate (and higher background noise) was noted for the examination with autologous platelets. This goes hand in hand with a lower rate of marked platelets in the case of autologous exam. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows imaging results of homologous and autologous \u003csup\u003e111\u003c/sup\u003eIn-radiolabeled platelet injection right after injection and three days after.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe conducted a platelet lifespan evaluation and explored a potential sequestration site in a young patient with severe thrombocytopenia associated with an ITP therapeutic escape. \u003csup\u003e111\u003c/sup\u003eIn-radiolabeled homologous platelets were used to perform the examination with a platelet count of 9 G.L\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. These explorations are known to be effective predictors of a good response to splenectomy in case of isolated splenic sequestration. Splenectomy can be avoided if no sequestration, mixed or hepatic sequestration are shown [\u003cspan additionalcitationids=\"CR14 CR15\" citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThere is insufficient evidence to support strong management recommendations on the management of ITP. Splenectomy comes in second-line therapy after corticosteroids, TPO-RA and Rituximab, and it is generally delayed for at least 1 year after diagnosis. Ancient and actual international recommendations do not mention platelet survival and sequestration examination to undergo splenectomy in ITP [\u003cspan additionalcitationids=\"CR18\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Recent studies demonstrate that radiolabeled platelet exploration is useful to guide treatment [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e, \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. In children, it is advisable to avoid unnecessary splenectomies, as it is important for them to remain protected against infections caused by particularly encapsulated bacteria, without antibiotic prophylaxis or vaccination, especially as it is known that many children are likely to experience spontaneous remission of ITP [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn our case, avoiding splenectomy that certainly would not improve the ITP severity was important both physically and psychologically. An uncommon ITP phenomenon identified as diffuse endovascular destruction of immunological cause was then suspected for this child, which enabled to avoid an unnecessary splenectomy.\u003c/p\u003e \u003cp\u003eOur patient was treated by TPO-RA and the possibility of interference with the exam was raised. A study shows that TPO-RA may overcompensate platelet destruction in ITP and may reduce platelet destruction rate [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. Another more recent study suggests that TPO-RA doesn\u0026rsquo;t modify either the site of platelet destruction or the platelet survival and raises the fact that the increased estimated platelet production is not sufficient to overcome the platelet destruction by the immune system [\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e]. As there was no difference between the results of the homologous and the autologous exams, we concluded that there was no interference from TPO-RA treatment in our case.\u003c/p\u003e \u003cp\u003eResults of the homologous procedure has been validated remotely with a radiolabeled autologous platelets exploration which was achieved following the intensification of TPO-RA treatment. The use of homologous platelets should remain the exception, due to transfusion issues and the difficulty of supply and storage of PC. However, homologous platelet scintigraphy could help clinicians to choose splenectomy as a treatment option for ITP in children with very low platelet count. Additional, more systematic studies on larger populations are needed to confirm the indication of homologous platelet scintigraphy.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eANSM: French national agency for the safety of medicines and health products\u003c/p\u003e\n\u003cp\u003eEFS: French blood establishment\u003c/p\u003e\n\u003cp\u003eITP: immunologic thrombocytopenic purpura\u003c/p\u003e\n\u003cp\u003ePC: platelet concentrate\u003c/p\u003e\n\u003cp\u003eROI: Region of interest\u003c/p\u003e\n\u003cp\u003eSPECT: single-photon emission computerized tomography\u003c/p\u003e\n\u003cp\u003eTPO-RA: thrombopoietin receptor-agonists\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cu\u003eEthics approval and consent to participate\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThis study was conducted in accordance with the ethical standards as laid down in the 1964 Declaration of Helsinki and its later amendments or comparable ethical standards. It was approved by the\u0026nbsp;Montpellier university hospital\u0026rsquo;s\u0026nbsp;local institutional review board under the number 2024-01-010 the 5\u003csup\u003eth\u003c/sup\u003e February 2024. Written information was given to the patient\u0026rsquo;s parents.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eConsent for publication\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from the patient\u0026rsquo;s parents for publication of this study and accompanying images.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAvailability of data and material\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets used and/or analysed during the current study are available from the corresponding author upon reasonable request.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eCompeting interests\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eFunding\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have received no funding for this study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAuthors\u0026apos; contributions\u0026nbsp;\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eJD, FK, LD, VK, GP, VT, DM, AB, and TP contributed to the study conception and design. Material preparation, data collection and analysis were performed by JD, AB, FK, and TP. The first draft of the manuscript was written by JD. All authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cu\u003eAcknowledgements\u003c/u\u003e\u003c/p\u003e\n\u003cp\u003eWe would like to thank Aur\u0026eacute;lie Conte and the French blood establishment (EFS) for their work and for allowing us to carry out the homologous test by providing the donor\u0026rsquo;s platelets.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eInternational Committee for Standardization in Hematology. PROPOSED RECOMMENDATIONS FOR MEASUREMENT OF SERUM IRON IN HUMAN BLOOD. Br J Haematol. 1971;20:451\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNajean Y, Dufour V, Rain JD, Toubert ME. The site of platelet destruction in thrombocytopenic purpura as a predictive index of the efficacy of splenectomy. Br J Haematol. 1991;79:271\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeters AM, Porter JB, Saverymuttu SH, Malik F, Zuiable A, Lavender JP, et al. The kinetics of unmatched and HLA-matched \u003csup\u003e111\u003c/sup\u003e In-labelled homologous platelets in recipients with chronic marrow hypoplasia and anti-platelet immunity. Br J Haematol. 1985;60:117\u0026ndash;27.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHammersmith SM, Jacobson AF, Mankoff DA. Scintigraphy with indium-111-labeled homologous (donor) platelets in the platelet transfusion refractory bone marrow transplant patient. J Nucl Med Off Publ Soc Nucl Med. 1997;38:1135\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmidt RP, Lentle BC. Hemangioma with Consumptive Coagulopathy (Kasabach-Merritt Syndrome) Detection by lndium-111 Oxine-labeled Platelets. Clin Nucl Med. 1984;9:389\u0026ndash;91.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eCastle V, Coates G, Kelton JG, Andrew M. 111In-oxine platelet survivals in thrombocytopenic infants. Blood. 1987;70:652\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMathias CJ, Welch MJ. Radiolabeling of platelets. Semin Nucl Med. 1984;14:118\u0026ndash;27.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBonnes pratiques de pr\u0026eacute;paration [Internet]. ANSM. 2023 [cit\u0026eacute; 19 juill 2023]. Disponible sur: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ansm.sante.fr/documents/reference/bonnes-pratiques-de-preparation\u003c/span\u003e\u003cspan address=\"https://ansm.sante.fr/documents/reference/bonnes-pratiques-de-preparation\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNational Nuclear Data Center. Nuclear Decay Data of Indium-111 in the MIRD Format [Internet]. [cit\u0026eacute; 19 juill 2023]. Disponible sur: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://www.nndc.bnl.gov/nudat3/mird/\u003c/span\u003e\u003cspan address=\"https://www.nndc.bnl.gov/nudat3/mird/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePeters A, Lavender J. Platelet Kinetics with Indium-111 Platelets: Comparison with Chromium-51 Platelets. Semin Thromb Hemost. 1983;9:100\u0026ndash;14.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSnyder E, Raife T, Lin L, Cimino G, Metzel P, Rheinschmidt M, et al. Recovery and life span of \u003csup\u003e111\u003c/sup\u003e indium-radiolabeled platelets treated with pathogen inactivation with amotosalen HCl (S-59) and ultraviolet A light: RECOVERY AND LIFE SPAN OF PCT PLTs. Transfus (Paris). 2004;44:1732\u0026ndash;40.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eANSM. Bonnes pratiques transfusionnelles [Internet]. ANSM. 2020 [cit\u0026eacute; 19 juill 2023]. Disponible sur: \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://ansm.sante.fr/documents/reference/bonnes-pratiques-transfusionnelles\u003c/span\u003e\u003cspan address=\"https://ansm.sante.fr/documents/reference/bonnes-pratiques-transfusionnelles\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLamy T, Moisan A, Dauriac C, Ghandour C, Morice P, Le Prise PY. Splenectomy in idiopathic thrombocytopenic purpura: its correlation with the sequestration of autologous indium-111-labeled platelets. J Nucl Med Off Publ Soc Nucl Med. 1993;34:182\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSarpatwari A, Provan D, Erqou S, Sobnack R, David Tai FW, Newland AC. Autologous 111In-labelled platelet sequestration studies in patients with primary immune thrombocytopenia (ITP) prior to splenectomy: a report from the United Kingdom ITP Registry: 111Indium Studies Prior to Splenectomy for ITP. Br J Haematol. 2010;151:477\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRoca M, Mu\u0026ntilde;iz-Diaz E, Mora J, Romero-Zayas I, Ram\u0026oacute;n O, Roig I, et al. The scintigraphic index spleen/liver at 30 minutes predicts the success of splenectomy in persistent and chronic primary immune thrombocytopenia. Am J Hematol. 2011;86:909\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKazi S, Mckiddie F, Anderson J, Bagot C, Duncan C, Drummond M, et al. Autologous \u003csup\u003e111\u003c/sup\u003e In-labelled platelet scan as a predictor of splenectomy outcome in ITP. Br J Haematol. 2019;184:1043\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNeunert C, Lim W, Crowther M, Cohen A, Solberg L, Crowther MA. The American Society of Hematology 2011 evidence-based practice guideline for immune thrombocytopenia. Blood. 2011;117:4190\u0026ndash;207.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eD\u0026rsquo;Orazio JA, Neely J, Farhoudi N. ITP in Children: Pathophysiology and Current Treatment Approaches. J Pediatr Hematol Oncol. 2013;35:1\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNeunert C, Terrell DR, Arnold DM, Buchanan G, Cines DB, Cooper N, et al. American Society of Hematology 2019 guidelines for immune thrombocytopenia. Blood Adv. 2019;3:3829\u0026ndash;66.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRatnasingam S, Reid AS, Ma D, Bucki-Smith D, Gwini SM, Seneviratna L, et al. Indium‐labelled autologous platelet sequestration studies predict response to splenectomy in immune thrombocytopenia: an Australian experience. Intern Med J. 2022;52:1387\u0026ndash;93.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDurand P, Pottier V, Mesguich C, Debordeaux F, Lazaro E, Viallard J-F, et al. Utility of indium-111 platelet scintigraphy for understanding the mechanism of thrombocytopenia associated with myelodysplastic syndromes and chronic myelomonocytic leukemia. Exp Hematol Oncol. 2023;12:50.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeyer O, Herzig E, Salama A. Platelet Kinetics in Idiopathic Thrombocytopenic Purpura Patients Treated with Thrombopoietin Receptor Agonists. Transfus Med Hemotherapy. 2012;39:5\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMahevas M, Van Eeckhoudt S, Moulis G, Limal N, Languille L, Bierling P, et al. Autologous \u003csup\u003e111\u003c/sup\u003e Indium-oxinate‐labelled platelet sequestration study in patients with immune thrombocytopenia treated by thrombopoietin receptor‐agonists. Br J Haematol [Internet]. 2019. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1111/bjh.15890\u003c/span\u003e\u003cspan address=\"10.1111/bjh.15890\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. [cit\u0026eacute; 20 juill 2023];186. Disponible sur. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://onlinelibrary.wiley.com/doi/\u003c/span\u003e\u003cspan address=\"https://onlinelibrary.wiley.com/doi/\" targettype=\"URL\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-4017056/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4017056/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose \u003c/strong\u003eImmunologic thrombocytopenic purpura (ITP) is a condition that affects 4 to 18 per 100 000 children every year. In most cases, spontaneous remission occurs, but splenectomy can be proposed to diminish excessive destruction of platelets when ITP is refractory. Exploring the site of platelet sequestration may help to better predict potential poor responders to splenectomy if no spleen sequestration is highlighted. The radiolabeled platelet sequestration test may be an option but can be difficult to perform in children with very few platelets.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods \u003c/strong\u003eA twelve-year-old boy suffering from chronical ITP was referred to evaluate platelet survival and sequestration, to discuss splenectomy. The patient was refractory to therapy and his platelet count consistently remained below 10 G.L-1. An exceptional procedure was set up to use homologous platelets to perform a radiolabeled platelet survival and sequestration test.\u0026nbsp;A radiolabeled autologous platelet exam was carried five months later to confirm the test.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults \u003c/strong\u003eSignificantly reduced platelet lifespan and half-life was observed for both techniques. The splenic and hepatic ratio were below 1.2 at all time points, meaning that there was no organ sequestration.\u0026nbsp;The fact that we confirmed our test by two different methods allowed us to reject the indication for splenectomy in this child. Strict intravascular destruction has been confirmed. \u003cstrong\u003eConclusions\u003c/strong\u003e 111In-radiolabeled homologous platelets were used to perform the examination and confirmed the results obtained with autologous platelets. Homologous platelet scintigraphy could help clinicians to choose splenectomy as a treatment option for ITP in children with very low platelet count. Work must be done to promote its use.\u003c/p\u003e","manuscriptTitle":"Homologous 111In-radiolabeled platelet survival and sequestration exploration for refractory immunologic thrombocytopenic purpura in children: a strategy to avoid unnecessary splenectomy","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-03-19 15:40:20","doi":"10.21203/rs.3.rs-4017056/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"f5f8e9b9-6d19-4e38-ab45-9b33515638e4","owner":[],"postedDate":"March 19th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2024-04-05T10:47:58+00:00","versionOfRecord":[],"versionCreatedAt":"2024-03-19 15:40:20","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-4017056","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4017056","identity":"rs-4017056","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}