Study to inform definitive trial of 99mTc-sestaMIBI SPECT/CT for T1 renal tumors

A recent study (MULTI-MIBI) has demonstrated the feasibility of recruitment into a trial of ^99mTc-sestaMIBI SPECT/CT for the diagnosis of T1 renal tumors, laying the groundwork for a future definitive trial of the diagnostic.

Hannah Warren, PhD candidate

The findings were presented at the 16th European Multidisciplinary Congress on Urological Cancers in Lisbon, Portugal.¹

“Detection of incidental renal tumors is on the rise, which reflects our growing use of cross-sectional imaging in urology,” explained presenting author Hannah Warren, a PhD candidate and Clinical Research Fellow at the University College London, during the presentation. “But we know from surgical series that 30% of these tumors are benign. Surgical excision of an asymptomatic and benign tumor is over-treatment for the vast majority, but we lack good diagnostic tests.”

Thus, the prospective MULTI-MIBI study sought to evaluate the feasibility of recruitment for a large-scale, multi-center diagnostic accuracy study of ^99mTc-sestaMIBI SPECT/CT in benign tumors.

According to Warren, “This modality is already in use in most hospitals for parathyroid and cardiac imaging, so it's easy to roll out.”

For the study, all patients who were referred to 1 of 6 clinical sites in the UK with a T1 tumor were screened for the study. To be eligible for enrollment, patients needed to have a solid cT1 renal mass measuring 2 to 7 cm and no known allergy to radiotracer. Additionally, patients needed to be undergoing biopsy or surgery as part of standard of care. Patients were excluded if they were pregnant or breastfeeding.

In total, the study enrolled 50 of the 95 patients (46.3%; 95% CI, 36.7-56.1%) who were approached. These patients were enrolled within 15 months, with a median recruitment rate of 3.5 patients per month (IQR, 1.75-4). Among all participants enrolled, 46 were included in the final analysis. Four patients were excluded due to having unevaluable histology.

Warren also noted, “Our study population was representative of the UK diversity according to local census data.”

For the study, ^99mTc-sestaMIBI SPECT/CT scans were obtained approximately 75 minutes following radiotracer injection, according to local expertise. These images (index test) were compared with histopathology from biopsy or surgical resection (reference tests).²

Overall, data showed that the sensitivity of ^99mTc-sestaMIBI SPECT/CT was 97% (95% CI, 84.2-99.9%), and the specificity was 53.8% (25.1-80.8%). The positive predictive value of the diagnostic was 84.2% (95% CI, 68.7-94%), and the negative predictive value was 87.5% (95% CI, 47.3-99.7%).

Warren added, “Essentially, this translates to us being able to potentially half the number of people undergoing surgery for benign tumors without missing a significant number of cancers.”

Additionally, data showed that inter-reader agreement in the study was near perfect, with a Gwet’s AC1 value of 0.9408 (95% CI, 0.64-1). Scans were also able to be reported by local clinicians following only a half day webinar on ^99mTc-sestaMIBI SPECT/CT image interpretation from experienced clinicians.

All patients in the study also had the opportunity to participate in a qualitative interview regarding facilitators and barriers to recruitment. According to Warren, these findings will be reported separately.

The authors also concluded that findings from the MULTI-MIBI study “will inform further work to evaluate the role and cost-effectiveness of MIBI for T1 renal tumors.”

References

1. Warren H, Wagner T, El-Sheikh S, et al. MULTI-centre feasibility study to assess the use of 99m Tc-sestaMIBI SPECT/CT in the diagnosis of kidney tumours (MULTI-MIBI study). Presented at: 16th European Multidisciplinary Congress on Urological Cancers. November 7-10, 2024. Lisbon, Portugal. Abstract O12

2. Warren H, Wagner T, Gorin MA, et al. Protocol for a MULTI-centre feasibility study to assess the use of 99mTc-sestaMIBI SPECT/CT in the diagnosis of kidney tumours (MULTI-MIBI study). BMJ Open. 2023;13(1):e067496. doi:10.1136/bmjopen-2022-067496