Investigation of the differential biology between benign and malignant renal masses using advanced magnetic resonance imaging techniques (IBM-Renal): a multi-arm, non-randomised feasibility study

Introduction Localised renal masses are an increasing burden on healthcare due to the rising number of cases. However, conventional imaging cannot reliably distinguish between benign and malignant renal masses, and renal mass biopsies are unable to characterise the entirety of the tumour due to sampling error, which may lead to delayed treatment or overtreatment. There is an unmet clinical need to develop novel imaging techniques to characterise renal masses more accurately. Renal tumours demonstrate characteristic metabolic reprogramming, and novel MRI methods have the potential to detect these metabolic perturbations which may therefore aid accurate characterisation. Here we present our study protocol for the Investigation of the differential biology of Benign and Malignant renal masses using advanced magnetic resonance imaging techniques (IBM-Renal). Methods and analysis IBM-Renal is a multi-arm, single-centre, non-randomised, feasibility study with the aim to provide preliminary evidence for the potential role of the novel MRI techniques to phenotype localised renal lesions. 30 patients with localised renal masses will be recruited to three imaging arms, with 10 patients in each: (1) hyperpolarised [1- 13 C]-pyruvate MRI (HP 13 C-MRI), (2) deuterium metabolic imaging (DMI), and (3) sodium MRI ( 23 Na-MRI). The diagnosis will be made on samples acquired at biopsy or at surgery. The primary objective is to investigate whether novel MRI techniques can identify the differences between benign and malignant tumours, while the secondary objectives aim to assess how complementary the techniques are, and if they provide additional information. Exploratory objective will be to link imaging findings with clinical data and molecular analyses for biological validation of the novel MRI techniques. Ethics and dissemination This study was ethically approved (UK REC HRA: 22/EE/0136; current protocol version 2.1 dated 11/08/2022). The plans for dissemination include presentations at conferences, publications in scientific journals, a doctoral thesis, and patient and public involvement. Registration details ClinicalTrials.gov : NCT06016075 Strengths and limitations of this study IBM-renal is the first prospective study to investigate the role of deuterium metabolic imaging and sodium MRI for the characterisation of indeterminate renal masses. Combining different MRI techniques in the same patient will allow a direct comparison and determining whether they provide additional data. The clinical team is multidisciplinary, enabling a multimodal assessment of these renal masses, including clinical, imaging, pathology data. Limitations of the study include potential pathological undergrading of benign renal masses, as some of these diagnoses are based on a single biopsy. As a feasibility study, the sample size is small, but the primary outcomes can be used to inform a large-scale study.