Clear Cell Renal Cell Carcinoma Metastases Visibility: Split-Bolus Single Scan vs. Portal Venous Phase CT

Objective To assess the impact of split-bolus (SB) single scan CT on the conspicuity of clear cell renal cell carcinoma (ccRCC) metastases compared to single-bolus injection.

This retrospective cohort study included consecutive patients with histologically proven metastatic ccRCC who underwent both SB and single-bolus portal venous abdominal CT within 6 months between 2017 and 2022 in a single tertiary center. SB CT utilized BMI-adjusted contrast dose and kVp (80-120) with concurrent arterial and portal venous phases. Single bolus CT utilized BMI-adjusted contrast dose at 120kVp at the portal venous phase. Wilcoxon rank test compared the conspicuity of metastases between the protocols.

Of the 47 patients, 80.9% were male, with a mean age of 67 ± 10.4 years and a BMI of 27.1 ± 5.7. There were 48 paired CTs performed with a median interval of 93 days. Contrast dose was 143 ± 27 cc for SB and 108 ± 26 cc for single-bolus (p< 0.001). 66 metastases were analyzed, with an average size of 2 cm: 48.5% in the pancreas, 28.8% in skeletal muscle, and 22.7% in the liver. The median contrast-to-noise ratio (CNR) was higher with SB compared to single-bolus for all metastases (3.0 vs. 1.4), pancreatic metastases (2.7 vs. 1.4), muscle metastases (5.2 vs. 2.0), and liver metastases (2.8 vs. 0.9), all p< 0.001.

SB scan provides dramatically higher conspicuity of ccRCC metastases as compared to single-bolus portal venous CT. Competing Interest Statement The authors have declared no competing interest. Funding Statement This study did not receive any funding Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of Beth Israel Deaconess Medical Center gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Footnotes Other authors: Francesca Rigiroli, M.D., frigirol{at}bidmc.harvard.edu, Alexander Brook, Ph.D., abrook{at}bidmc.harvard.edu, Olga Brook, M.D., obrook{at}bidmc.harvard.edu The authors have no conflict of interest to declare. Data Availability All data produced in the present study are available upon reasonable request to the authors