Role of 99m Tc-sestamibi single photon emission computed tomography/computed tomography in the characterization of...

Technetium-99 m ( 99m Tc)-sestamibi, a lipophilic cationic molecule that accumulates in cells rich in mitochondria, can help to characterize the solid renal masses. This study evaluated the accuracy of 99m Tc-sestamibi single photon emission computed tomography/computed tomography (SPECT/CT) in the characterization of solid renal lesions, and we explored whether dynamic imaging could provide added diagnostic value over delayed SPECT/CT in the differentiation of renal lesions into benign and malignant.

In this prospective study, all referred patients with a solid renal mass who have not undergone any intervention underwent 99m Tc-sestamibi SPECT/CT imaging and, based on lesion (TLsC) to renal background uptake ratio (TRBKG) with a cutoff 0.5, the renal masses were classified as either positive or negative for 99m Tc-sestamibi uptake, and the results compared with final histopathological reports.

Thirty-six patients (28 men and 8 women) were included, of which five patients' renal lesions were 99m Tc-sestamibi positive and 31 were negative. Of the five 99m Tc-sestamibi-positive lesions, four were benign in nature, whereas 30 of 31 99m Tc-sestamibi-negative lesions were malignant. Thus, the sensitivity, specificity, and accuracy of 99m Tc-sestamibi for differentiation of benign and malignant renal lesions were 80% [95% confidence interval (CI), 37.56-96.38], 96.8% (95% CI, 83.81-99.43), and 94.4% (95% CI, 81.86-98.46), respectively. The area under the receiver operating characteristic curve was 0.935 (95% CI 0.84-1.00). Dynamic imaging showed no significant incremental value over delayed 99m Tc-sestamibi SPECT/CT for lesion classification (McNemar's exact P  = 1.00; Fisher's exact P  = 0.163).

The study showed high diagnostic accuracy of 99m Tc-sestamibi SPECT/CT in differentiating benign from malignant solid renal lesions. Its high specificity and negative predictive value make it a potential and valuable noninvasive diagnostic tool for characterizing solid renal lesions, thus guiding further management. Dynamic imaging, however, did not demonstrate incremental diagnostic value over delayed SPECT/CT for characterization of renal lesions.