99mTc-Sestamibi SPECT/CT and histopathological features of oncocytic renal neoplasia.

Background: ^99mTc-Sestamibi Single Photon Emission Computed Tomography/Computed Tomography (SPECT/CT) contributes to the non-invasive differentiation of renal oncocytoma (RO) from renal cell carcinoma (RCC) by characterising renal tumours as Sestamibi positive or Sestamibi negative regarding their ^99mTc-Sestamibi uptake compared to the non-tumoral renal parenchyma.

Purpose: To determine whether ^99mTc- Sestamibi uptake in renal tumour and the non-tumoral renal parenchyma measured using Standard Uptake Value (SUV) SPECT, has a beneficial role in differentiating RO from RCC.

Material and methods: Fifty-seven renal tumours from 52 patients were evaluated. In addition to visual evaluation of ^99mTc-Sestamibi uptake, SUV_max measurements were performed in the renal tumour and the ipsilateral non-tumoral renal parenchyma. Analysis of the area under the receiver operating characteristic curve identified an optimal cut-off value for detecting RO, based on the relative ratio of ^99mTc- Sestamibi uptake.

Results: Semiquantitative evaluation of ^99mTc-Sestamibi uptake did not improve the performance of ^99mTc- Sestamibi SPECT/CT in detecting RO. ^99mTc- Sestamibi SPECT/CT identifies a group of mostly indolent Sestamibi-positive tumours with low malignant potential containing RO, Low-Grade Oncocytic Tumours, Hybrid Oncocytic Tumours, and a subset of chromophobe RCCs.

Conclusion: The imaging limitations for accurate differentiation of Sestamibi-positive renal tumours mirror the recognised diagnostic complexities of the histopathologic evaluation of oncocytic neoplasia. Patients with Sestamibi-positive renal tumours could be better suited for biopsy and follow-up, according to the current active surveillance protocols.