Presented by: Tzach Aviv MD
Institute of Urology, Rabin Medical Center - Beilinson Hospital

Introduction

Conventional imaging studies (i.e. CT or MRI) cannot reliably differentiate between benign and malignant renal masses. Recently, FAPI (fibroblast activating protein inhibitor) based PET/CT has been investigated in lung, breast, and GI cancers with promising results. We assessed the role of GA⁶⁸-FAPI PET/CT in the evaluation of renal masses.

Materials

A prospective case series of patients with enhancing localized renal mass who were referred for partial or radical nephrectomy. All patients completed GA⁶⁸-FAPI PET/CT before surgery. The scans were interpreted by two nuclear medicine specialists. Demographic, clinical, and histopathological data were extracted. The standardized uptake values (SUV) were compared between benign and malignant lesions. The local institutional review board approved the study and all patients provided written informed consent to participate in the study.

Results

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We evaluated 12 renal masses in 10 patients. The average age was 60±8 years and the median mass size was 2.3 cm (IQR 1.7-3.9). 70% of the tumors were malignant. Until the submission of this abstract, 9 patients with 10 renal masses underwent surgery. 70% of the tumors were malignant, including 4 (40%) Papillary RCC, 2 (20%) Clear cell carcinoma, and 1 (10%) chromophobe RCC. Of 3 benign lesions  2 (20%) were angiomylipomas and 1 (10%) oncocytoma. Increased tracer uptake was subjectively visualized in the tumors and was stronger in benign lesions. The median SUVmean and SUVmax of benign and malignant lesions were 5.4 (IQR 4.7-8.4) and 1.9 (IQR 1.6-2.3), p=0.02; and 10.1 (IQR 8.3-15.6) and 2.6 (IQR 2.3-4), p=0.02,  respectively.

Conclusion

This is the first study to highlight GA⁶⁸-FAPI uptake in localized renal masses. We observed increased tracer uptake in benign versus malignant renal tumors. This supports further assessment of this tracer in a larger patient cohort.

Funding

None

Lead Authors

Hana Bernstine, MD
Department of Nuclear Medicine, Rabin Medical Center - Beilinson Hospital

Andrei Nadu, MD
Institute of Urology, Rabin Medical Center - Beilinson Hospital

David Groshar, MD
Department of Nuclear Medicine, Rabin Medical Center - Beilinson Hospital

Jack Baniel, MD
Institute of Urology, Rabin Medical Center - Beilinson Hospital

Shay Golan, MD
Institute of Urology, Rabin Medical Center - Beilinson Hospital