Objectives: To determine the effectiveness of technetium-99m (99m Tc)-sestamibi single-photon emission computerised tomography/computerised tomography (SPECT/CT) in distinguishing between malignant and benign renal lesions.
Patients and methods: Between June 2018 and October 2020 all patients with new indeterminate small renal masses (SRMs) underwent 99m Tc-sestamibi renal SPECT/CT before biopsy or surgery. The accuracy of 99m Tc-sestamibi imaging diagnoses was assessed against histopathology. Receiver operating characteristic (ROC) analysis was used to determine the optimum cut-off for the tumour:normal uptake ratio. Logistic regression was used to determine if quantitative analysis significantly added to visual interpretation alone.
Results: A total of 74 patients with SRMs were investigated with 99m Tc-sestamibi SPECT/CT. The SPECT/CT correctly identified 49 malignant tumours and 11 benign tumours, resulting in a sensitivity of 0.89 (95% confidence interval [CI] 0.77-0.95) and a specificity of 0.73 (95% CI 0.45-0.91). The ROC analysis of uptake ratios demonstrated that a tumour:normal uptake ratio of 0.41 provided optimal diagnostic accuracy (sensitivity 0.81, specificity 0.88, area under the curve 0.883 [95% CI 0.794-0.971]). The uptake ratio was also highly significant in excluding malignancy on univariate logistic regression analysis whereby the higher the uptake ratio, the lower the chances were for malignancy (odds ratio 0.009, 95% CI 0.001-0.118, P < 0.001). However, this did not improve diagnostic accuracy when compared to visual interpretation alone.
Conclusion: 99m Tc-sestamibi SPECT/CT is a non-invasive technique with good accuracy in determining if a SRM is benign or malignant.
Keywords: 99mTc-sestamibi SPECT/CT; RCC; benign vs malignant; oncocytoma; small renal masses.
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