Validation of in vivo nodal staging of solid malignancies with USPIO-enhanced MRI: a workflow protocol

Abstract BackgroundIn various cancer types, the first step towards extended metastatic disease is the presence of lymph node metastases. Imaging methods with sufficient diagnostic accuracy are required to personalize treatment. Lymph node metastases can be detected with ultrasmall superparamagnetic iron oxide (USPIO)-enhanced magnetic resonance imaging (MRI), but this method needs validation. Here, a workflow is presented which is designed to compare MRI-visible lymph nodes on a node-to-node basis with histopathology. MethodsIn patients with prostate, rectal, periampullary, esophageal, and head-and-neck cancer, in vivo USPIO-enhanced MRI was performed to detect lymph nodes suspicious for harboring metastases. After lymphadenectomy, but before histopathological assessment, a 7 Tesla (T) preclinical ex vivo MRI of the surgical specimen was performed, and in vivo MR-images were radiologically matched to ex vivo MR images. Lymph nodes were annotated on the ex vivo MRI for an MR-guided pathological examination of the specimens. ResultsMatching lymph nodes of ex vivo MRI to pathology was feasible in all cancer types. The annotated ex vivo MR images enabled a comparison between USPIO-enhanced in vivo MRI and histopathology which allowed for analyses on nodal, or at least on nodal station level.ConclusionsA workflow was developed to validate in vivo USPIO-enhanced MRI with histopathology. Guiding the pathologist towards lymph nodes in the resection specimens during histopathological work-up allowed analysis at nodal level, or at least nodal station level of in vivo suspicious lymph nodes with corresponding histopathology, providing direct information for validation of in vivo USPIO-enhanced MRI detected lymph nodes. Trial registrationVALINODE data is collected from patients undergoing USPIO-enhanced MRI in the clinical setting. Therefore, the trial has not been registered in an online trial register. 7TNANO1 is registered at Clinicaltrials.gov: NCT02751606, April 26 2016 (https://clinicaltrials.gov/ct2/show/NCT02751606). NANO-PANC is registered at Clinicaltrials.gov: NCT04311047, March 17 2020 (https://www.clinicaltrials.gov/ct2/show/NCT04311047). PRECIES is registered in the Dutch Trial Register: NTR6072, August 5 2016 (https://www.trialregister.nl/trial/5797). USPIO-NECK is registered at Clinicaltrials.gov: NCT03817307, January 25 2019 (https://clinicaltrials.gov/ct2/show/NCT03817307).