Visual evaluation and differentiation of renal oncocytomas from renal cell carcinomas by means of Sestamibi SPECT/CT.

Objectives: Despite the progress in the quality of multiphasic CT and MRI scans, it is still difficult to fully characterize a solid kidney lesion. Approximately 10% of all solid renal tumours turn out to be oncocytomas. In actual clinical practice, this is verified only following unnecessary surgery or a renal biopsy/ablation. The objective of our pilot study examines whether ^99mTc-Sestamibi SPECT/CT can play a crucial role in the characterization of solid renal neoplasms and the differentiation of oncocytomas from renal cell carcinomas.

Methods: The study included 27 patients identified with 31 solid renal lesions. All patients were discussed in a multidisciplinary conference and a decision for surgery or biopsy was taken. Prior to invasive procedures, patients underwent a SPECT/CT with ^99mTc-Sestamibi. Visual evaluation was performed and any focal ^99mTc-Sestamibi uptake detected on SPECT in the localisation of tumour was considered as positive.

Results: Eleven out of 12 oncocytomas displayed positive uptake of ^99mTc-Sestamibi. 3 hybrid tumours (mixed type oncocytoma and chromophobe renal cancer) were positive on SPECT/CT. 1 papillary renal cell carcinoma had a slight uptake of ^99mTc-Sestamibi. The remaining 11 renal cell carcinomas were Sestamibi negative.

Conclusion: Differentiation of benign renal oncocytomas from renal cell carcinomas seems very promising on ^99mTc-Sestamibi SPECT/CT examination. Additional supplement to visual evaluation, i.e. quantitative tools, should be sought for an accurate estimate of biological behaviour and hence a secure diagnosis. 2