부산대학교 도서관

An accurate and non-invasive histologic assessment of renal masses remains elusive, as approximately 15% of resected renal masses prove benign upon resection. Oncocytomas and hybrid oncocytoma/chromophobe tumors (HOCTs) are the most commonly-resected oncologically low-risk masses and are not reliably distinguished from malignant lesions with standard cross-sectional imaging. Histologically, these tumors are notable for densely-packed mitochondria. Technetium-99m-sestamibi single-photon emission CT/ x-ray CT is a nuclear imaging modality that utilizes a mitochondria-targeting tracer. Early series using 99mTc-sestamibi SPECT/CT showed promise in differentiating renal cell carcinoma (RCC) from oncocytomas and HOCTs, but recently published data from our institution found that oncocytomas still accounted for 20% of lesions with low 99mTc-sestamibi tracer uptake, as qualitatively interpreted by a senior nuclear radiologist. Here, we asses performance of 99mTc-sestamibi scans utilizing quantitative assessment thresholds, hypothesizing that this may improve test characteristics over qualitative assessments. Patients undergoing 99mTc-sestamibi SPECT/CT for evaluation of renal masses between February 2020 and December 2021 were included in our analysis. A mass was labeled as "hot" by the radiologist if its 99mTc-sestamibi uptake was qualitatively equivalent or higher than that of the ipsilateral renal parenchyma; otherwise it was labeled as "cold". Using nuclear medicine image processing software, TBRs were calculated by comparing signal counts of the masses to those of the normal ipsilateral renal parenchyma using manually generated regions of interest. Quantitative "hot"/"cold" determinations for each mass were then re-evaluated using previously published TBR cutoffs of 0.46 and 0.6. Masses for which TBRs could not be calculated were assumed to have unchanged classifications on quantitative analysis. Qualitative and quantitative 99mTc-sestamibi SPECT/CT findings were then correlated to histology for masses that underwent pathologic confirmation via biopsy or surgical excision. 78 patients underwent 99mTc-sestamibi SPECT/CT for 98 renal masses. 52 masses had diagnostic pathology available from biopsy or surgical excision. Of these, 7 were "hot" (1 RCC, 6 oncocytomas) and 45 were "cold" (34 RCC, 2 non-RCC malignancies, 9 oncocytomas). The negative predictive value of qualitatively-interpreted "cold" 99mTc-sestamibi scans for ruling out oncocytoma was 80%. 1/52 (1.9%) malignant masses were interpreted as "hot" and;likely benign. When a TBR cutoff of 0.46 was applied, 17/45 "cold" masses were reclassified as "hot" (13 RCC, 1 non-RCC malignancy, 6 oncocytomas). For a TBR cutoff of 0.6, 6/45 "cold" masses were reclassified as "hot" (1 RCC, 1 non-RCC malignancy, 4 oncocytomas) while 1 "hot" RCC was reclassified as "cold" (Figure 1).; TBR cutoffs of 0.46 and 0.6 improved the NPV;of 99mTc-sestamibi SPECT/CT to 89% and 88% but increased the rate of "hot" malignant tumors to 23.1% and 3.8%, respectively. When assessing histology of renal masses, applying previously-published quantitative TBR cutoffs to 99mTc-sestamibi SPECT/CT provides <10% improvement in the negative predictive value for ruling out oncocytomas compared to previously published qualitative interpretations of these scans. Conversely, the use of these thresholds in place of qualitative assessments tends to categorize more RCCs as "hot," thereby erroneously mimicking oncocytomas. Further work is needed to determine whether 99mTc-sestamibi SPECT/CT has a role in routine clinical practice. [ABSTRACT FROM AUTHOR]