Sestamibi SPECT CT for indeterminate renal lesions: A single center experience
Alison Levy, MD, Esther Finney, MD, Yamin Dou, MD, Andrea Sorcini, MD, David Canes, MD.
Lahey Hospital, Burlington, MA, USA.
BACKGROUND: Incidentally discovered small renal masses are a heterogeneous group, spanning a spectrum from benign histology to indolent malignancies to aggressive phenotypes. Renal mass biopsy is warranted when the result would alter management, but the procedure is not without morbidity, and the non-diagnostic rate is 8-14%. Dual goals are to treat potentially threatening tumors, and to leave indolent or benign tumors untreated. Tc99m-Sestamibi SPECT/CT may help differentiate benign from malignant lesions, based on high density of mitochondria in oncocytomas and hybrid oncocytoma/chromophobe tumors. We present a single center experience with this technology for indeterminate renal masses.
METHODS: Our institutional radiologic database was queried for patients who underwent Tc99m-Sestamibi SPECT/CT for classification of indeterminate renal masses. Lesion uptake was compared to surrounding renal parenchyma and classified as increased or no uptake. Charts were reviewed retrospectively for patient demographics and tumor characteristics.
RESULTS: A total of 7 lesions were identified for which Tc99m-Sestamibi SPECT/CT was performed between 2020-2021. Five of seven lesions had increased radiotracer uptake, consistent with oncocytoma or oncocytic neoplasm. They all underwent biopsy as well, with pathology suggestive of oncocytic neoplasm. Patients with these “hot” lesions on Sestamibi scan all remain on active surveillance.
Two tumors were “cold” on Sestamibi, without radiotracer uptake. One underwent robotic-assisted laparoscopic partial nephrectomy. Final pathology demonstrated a cT1a chromophobe carcinoma with prominent eosinophils, a known scenario that could be considered a misleading Sestamibi SPECT/CT result, given the tumor’s indolent nature. The other patient is scheduled for an upcoming open partial nephrectomy.
CONCLUSIONS: Although Sestamibi SPECT/CT has yet to be featured as part of the AUA guideline algorithm for renal mass management, we find it to be a useful tool for select patients with indeterminate renal masses to support surveillance in those with “hot” lesions, or to bolster the decision to proceed with surgery in those with “cold” lesions suggestive of malignancy. Although our sample size is small, we hope that highlighting this imaging modality brings further awareness to its utility.
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