[99mTc]Tc-sestamibi SPECT/CT for the diagnosis of kidney tumours: a multi-centre feasibility study (MULTI-MIBI Study).

PURPOSE [99mTc]Tc-sestamibi SPECT/CT (MIBI SPECT/CT) is a promising tool to differentiate benign and malignant renal tumours. We tested feasibility of recruitment to a prospective, multi-centre diagnostic test evaluation study of MIBI SPECT/CT for T1 renal tumours. METHODS Consecutive adult patients with a newly-diagnosed clinical T1 (cT1) renal mass (2-7 cm) presenting to participating sites December 2022 - February 2024 were recruited and underwent MIBI SPECT/CT prior to histopathological diagnosis. Patients who accepted and declined participation and clinicians involved in study activities were invited to a semi-structured interview. The primary endpoint was feasibility of multi-centre recruitment. Secondary endpoints included qualitative assessment of barriers and facilitators to participation, estimates of MIBI SPECT/CT accuracy to detect cancer in order to power a definitive study, inter-rater agreement and identifying training needs for scan acquisition and interpretation. RESULTS Of 109 approached patients, 50 enrolled and underwent the study scan (45.8%, 95% CI 36.2-55.7%) across 6 sites. MIBI SPECT/CT scans were acquired and reported without the need for significant additional training. All scans were of adequate quality for interpretation. Sensitivity and specificity of MIBI SPECT/CT to detect cancer were 97.0% (95% CI 84.2-99.9%) and 53.8% (25.1-80.8%), respectively. CONCLUSION MULTI-MIBI has demonstrated feasibility of recruitment to a diagnostic evaluation study for T1 renal masses. Preliminary estimates of diagnostic accuracy suggest that MIBI SPECT/CT could reduce the number of patients with benign tumours undergoing surgery without missing a significant number of patients with malignant disease, however these results are limited by the small sample size in this feasibility study and a larger definitive study is needed prior to adoption in practice.