K-means clustering of hyperpolarised 13C-MRI identifies intratumoural perfusion/metabolism mismatch in renal cell carcinoma as best predictor of highest grade

Purpose Conventional renal mass biopsy approaches are inaccurate, potentially leading to undergrading. This study explored using hyperpolarised [1-13C]pyruvate MRI (HP 13C-MRI) to identify the most aggressive areas within the tumour of patients with clear cell renal cell carcinoma (ccRCC). Experimental design Six patients with ccRCC underwent presurgical HP 13C-MRI and conventional contrast-enhanced MRI. Three k-means clusters were computed by combining the k PL as a marker of metabolic activity, and the 13C-pyruvate signal-to-noise ratio (SNRPyr) as a perfusion surrogate. Combined clusters were compared to those derived from individual parameters and to those derived from percentage enhancement on nephrographic phase (%NG). The diagnostic performance of each cluster was assessed based on its ability to predict the highest histological tumour grade in postsurgical tissue samples. Tissues were further subject to MCT1 staining, RNA and whole-exome sequencing. Results Forty-four samples were collected in total. The clustering approach combining SNRPyr and k PL demonstrated the best performance for predicting highest tumour grade: specificity 85%; sensitivity 64%; positive predictive value 82%; and negative predictive value 68%. Epithelial MCT1 was identified as the major determinant of the HP 13C-MRI signal. The perfusion/metabolism mismatch cluster showed increased expression of metabolic genes and markers of aggressiveness, which may be due to genetic divergence. Conclusions This study demonstrates the potential of using HP 13C-MRI-derived metabolic clusters to identify intratumoral variations in tumour grade with high specificity. This work supports the use of metabolic imaging to guide biopsies to the most aggressive tumour regions, which could potentially reduce sampling error. ### Competing Interest Statement G.D.S. has received educational grants from Pfizer, AstraZeneca and Intuitive Surgical; consultancy fees from Pfizer, MSD, EUSA Pharma and CMR Surgical; Travel expenses from MSD and Pfizer; Speaker fees from Pfizer; Clinical lead (urology) National Kidney Cancer Audit and Topic Advisor for the NICE kidney cancer guideline. S.J.W. is a founder and director of Pinto Medical Consultancy. F.A.G. and J.D.K. have research grants from GlaxoSmithKline and AstraZeneca, and research support from GE Healthcare. F.A.G. has consulted for AstraZeneca on behalf of the University of Cambridge. ### Clinical Trial NCT03526809 ### Funding Statement This study was funded by Cancer Research UK (C19212/A27150, C19212/A29082, C19212/A16628). This research was supported by the Mark Foundation for Cancer Research (RG95043), Cancer Research UK Cambridge Centre (C9685/A25177 and CTRQQR-2021\100012), the NIHR Cambridge Biomedical Research Centre (BRC-1215-20014 and NIHR203312). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care. The authors have additional funding from the National Cancer Imaging Translational Accelerator (NCITA; C42780/A27066), the Cambridge Experimental Cancer Medicine Centre, the Mark Foundation Institute for Integrated Cancer Medicine (MFICM), and the Canadian Institute For Advanced Research (CIFAR). ### 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: East of England - Cambridge East Research Ethics Committee 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 All data that support the findings of this study are available on reasonable request from the corresponding author, on condition that this will not be used to deanonymize the patients. The data are not publicly available due to them containing information that could compromise research participant privacy and consent.