Utility of 18F-Prostate-Specific Membrane Antigen 1007 in Imaging of Tumor Thrombus of Renal Cell Carcinoma

Value of [68Ga]Ga-PSMA-11 PET/CT in Reflecting the Intra- and Intertumor Heterogeneity of Neovascularization in Clear Cell Renal Cell Carcinoma

Prostate-specific membrane antigen (PSMA) is a potential target for the diagnosis and treatment of angiogenesis in clear cell renal cell carcinoma (ccRCC). We aimed to investigate the degree of PSMA signal variability in ccRCC and assess its correlation with neovascularization in the tumor microenvironment. We included 120 patients with suspected renal tumors who underwent [68Ga]Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) scan before surgery in this retrospective study, including 98 ccRCC, 17 non-ccRCC, and 5 benign diseases. We compared the maximum standard uptake value (SUVmax) and tumor-to-liver ratio (TLR) of primary lesions in different groups and analyzed the diagnostic efficacy of PSMA imaging for ccRCC. The coefficient of variation (CV) of SUVmax, which reflects intertumor heterogeneity, and volume ratio (VR), which reflects intratumor heterogeneity, were obtained from PET imaging. We analyzed the correlation between SUVmax, PSMA immunohistiochemical (IHC) staining, microvessel density (MVD), and serum vascular endothelial growth factor (VEGF) and compared the inter- and intratumor heterogeneity of primary lesions and metastases. In our study, ccRCC showed significantly higher SUVmax and TLR compared to non-ccRCC and benign diseases (F = 14.48, p < 0.001; F = 14.49, p < 0.001). PSMA IHC staining exhibited moderate correlation with SUVmax (r = 0.421, p = 0.021) and MVD (r = 0.518, p = 0.003), but it was not correlated with serum VEGF (r = -0.003, p = 0.989). SUVmax had a moderate correlation with MVD (r = 0.448, p = 0.013) and serum VEGF (r = 0.345, p = 0.020). Serum VEGF exhibited a weak correlation with MVD (r = 0.338, p = 0.145). Based on the correlation, the SUVmax-to-angiogenesis model was validated. The mean SUVmax values of primary lesions, bone metastases, and tumor thrombi were 16.13, 18.69, and 6.02, respectively. The CV of the mean SUVmax was 58.5%, 55.9%, and 80.6%. The mean VR values of primary lesions, bone metastases, and tumor thrombi were 0.33, 0.46, and 0.75, respectively. The CV of the mean VR was 81.8%, 41.3%, and 26.7%. The SUVmax of primary lesions was significantly correlated with corresponding bone metastases and tumor thrombi (r = 0.52, p = 0.011; r = 0.87, p = 0.024). The SUVmax of primary lesion in localized ccRCC and advanced ccRCC showed no significant difference (p = 0.251), while the VR was significantly different (p = 0.049). In conclusion, [68Ga]Ga-PSMA-11 PET/CT is an effective molecular imaging tool for assessing angiogenesis and its heterogeneity and differentiating ccRCC. The SUVmax of primary lesions was significantly correlated with PSMA IHC staining, MVD, and serum VEGF. The intertumor heterogeneity of tumor thrombi was significantly higher than that of primary lesions and bone metastases. Primary lesions exhibited the highest intratumor heterogeneity, and lesions with high intratumor heterogeneity showed invasive behavior. PSMA uptake by primary lesions has a positive effect on metastasis.

Utility of PSMA PET/CT in Staging and Restaging of Renal Cell Carcinoma: A Systematic Review and Metaanalysis

Prostate-specific membrane antigen (PSMA) is expressed in the neovasculature of multiple solid tumors, including renal cell carcinoma (RCC). Studies have demonstrated promising results on the utility of PSMA-targeted PET/CT imaging in RCC. This report aims to provide a systematic review and metaanalysis on the utility and detection rate of PSMA PET/CT imaging in staging or evaluation of primary RCC and restaging of metastatic or recurrent RCC. Methods: Searches were performed in PubMed, Embase, and abstract proceedings (last updated, August 2023). Studies that provided a lesion-level detection rate of PSMA radiotracers in staging or restaging of RCC were included in the metaanalysis. The overall pooled detection rate with a 95% CI was estimated, and subgroup analysis was performed when feasible. Results: Nine studies comprising 152 patients (133 clear cell RCC [ccRCC], 19 other RCC subtypes) were included in the metaanalysis. The pooled detection rate of PSMA PET/CT in evaluation of primary or metastatic RCC was estimated to be 0.83 (95% CI, 0.67-0.92). Subgroup analysis showed a pooled PSMA detection rate of 0.74 (95% CI, 0.57-0.86) in staging or evaluation of primary RCC lesions and 0.87 (95% CI, 0.73-0.95) in restaging of metastatic or recurrent RCC. Analysis based on the type of radiotracer showed a pooled detection rate of 0.85 (95% CI, 0.62-0.95) for 68Ga-based PSMA tracers and 0.92 (95% CI, 0.76-0.97) for 18F-DCFPyL PET/CT. Furthermore, in metastatic ccRCC, the available data support a significantly higher detection rate for 18F-DCFPyL PET/CT than for conventional imaging modalities (2 studies). Conclusion: Our preliminary results show that PSMA PET/CT could be a promising alternative imaging modality for evaluating RCC, particularly metastatic ccRCC. Large prospective studies are warranted to confirm clinical utility in the staging and restaging of RCC.

Diffuse Intense 18 F-PSMA-1007 Uptake of the Breasts in a Woman With TFE3-Rearranged Renal Cell Carcinoma

ABSTRACT

A 23-year-old woman presenting with gross hematuria was found to have a left renal mass suspicious for renal cell carcinoma on abdominal contrast-enhanced CT. An 18 F-PSMA-1007 PET/CT scan was performed for evaluating the renal mass. 18 F-PSMA-1007 PET/CT showed focal activity of the renal mass, which was a transcription factor E3-rearranged renal cell carcinoma proved after nephrectomy. Surprisingly, diffuse heterogeneous intense activity of the bilateral breasts and moderate activity of the right accessory breast was observed. There was no morphological abnormality of the bilateral breasts and right accessory breast on CT images, indicating physiological PSMA uptake.

18 F-PSMA-1007 PET/CT in a Case of Von Hippel-Lindau Syndrome

ABSTRACT

We describe 18 F-PSMA-1007 PET/CT findings in case of von Hippel-Lindau syndrome with a cerebellar hemangioblastoma, 6 renal cell carcinomas in the bilateral kidneys, cystic lesions in the pancreas and left adrenal gland, and solid lesions in the bilateral epididymides. 18 F-PSMA-1007 PET/CT showed intense activity with SUV max of 111.3 of the cerebellar hemangioblastoma, variable activity with SUV max range of 6.4-37.6 of the renal cell carcinomas, and increased activity of the bilateral epididymal lesions (SUV max of 5.1 and 8.2 for the left and right epididymal lesions, respectively).

18 F-Choline Versus 68 Ga-PSMA-11 PET/CT Imaging Comparison in Incidental Clear Cell Renal Cell Carcinoma

ABSTRACT

Few articles in literature describe the potential usefulness of 18 F-choline PET/CT and particularly 68 Ga-PSMA-11 PET/CT in imaging of clear cell renal cell carcinoma (ccRCC). We report a unique comparison in literature between the 2 radiotracers in a patient who underwent left nephrectomy with diagnosis of ccRCC, grade 3. 68 Ga-PSMA-11 PET/CT confirmed its emerging role in imaging ccRCC, as the incidentally detected renal neoplasm showed a significant higher uptake in comparison to 18 F-choline PET/CT, inducing surgical indication.

Pituitary Metastasis of Renal Cell Carcinoma Characterized by 18F-Prostate-Specific Membrane Antigen-1007 PET/CT

ABSTRACT

Renal cell carcinoma (RCC) is one of the most common oncological diagnoses worldwide. Accurate staging and restaging imaging continue to be a priority in clinical practice as 20% to 30% of patients present with advanced metastatic disease at diagnosis, and 20% to 30% develop recurrence after surgical resection. We present a case of a 71-year-old man presenting with an isolated pituitary RCC metastasis accurately defined on 18F-prostate-specific membrane antigen-1007 masquerading as a macroadenoma on conventional imaging (CT and MRI). This demonstrates the potential utility of 18F-prostate-specific membrane antigen-1007 in characterizing RCC brain metastasis.