MRI and PSMA PET/CT of Biochemical Recurrence of Prostate Cancer.

Prostate cancer may recur several years after definitive treatment, such as prostatectomy or radiation therapy. A rise in serum prostate-specific antigen (PSA) level is the first sign of disease recurrence, and this is termed biochemical recurrence. Patients with biochemical recurrence have worse survival outcomes. Radiologic localization of recurrent disease helps in directing patient management, which may vary from active surveillance to salvage radiation therapy, androgen-deprivation therapy, or other forms of systemic and local therapy. The likelihood of detecting the site of recurrence increases with higher serum PSA level. MRI provides optimal diagnostic performance for evaluation of the prostatectomy bed. Prostate-specific membrane antigen (PSMA) PET radiotracers currently approved by the U.S. Food and Drug Administration demonstrate physiologic urinary excretion, which can obscure recurrence at the vesicourethral junction. However, MRI and PSMA PET/CT have comparable diagnostic performance for evaluation of local recurrence after external-beam radiation therapy or brachytherapy. PSMA PET/CT outperforms MRI in identifying recurrence involving the lymph nodes and bones. Caveats for use of both PSMA PET/CT and MRI do exist and may cause false-positive or false-negative results. Hence, these techniques have complementary roles and should be interpreted in conjunction with each other, taking the patient history and results of any additional prior imaging studies into account. Novel PSMA agents at various stages of investigation are being developed, and preliminary data show promising results; these agents may revolutionize the landscape of prostate cancer recurrence imaging in the future. ©RSNA, 2023 Quiz questions for this article are available through the Online Learning Center. See the invited commentary by Turkbey in this issue. The slide presentation from the RSNA Annual Meeting is available for this article.

Imaging features of immune checkpoint inhibitor-related nephritis with clinical correlation: a retrospective series of biopsy-proven cases.

OBJECTIVES: Imaging appearances of immune checkpoint inhibitor-related nephritis have not yet been described. The primary objective of this study is to describe the appearances of immunotherapy-related nephritis on computerized tomography (CT) and positron emission tomography (PET). The secondary objectives are to investigate the association of radiologic features with clinical outcomes. METHODS: CT and PET-CT scans before the initiation of immunotherapy (baseline), at nephritis, and after resolution of pathology-proven nephritis cases were reviewed. Total kidney volume, renal parenchymal SUVmax, renal pelvis SUVmax, and blood pool SUVmean were obtained. RESULTS: Thirty-four patients were included. The total kidney volume was significantly higher at nephritis compared to baseline (464.7 ± 96.8 mL vs. 371.7 ± 187.7 mL; p < 0.001). Fifteen patients (44.1%) had > 30% increase in total kidney volume, which was associated with significantly higher renal toxicity grade (p = 0.007), higher peak creatinine level (p = 0.004), and more aggressive medical treatment (p = 0.011). New/increasing perinephric fat stranding was noted in 10 patients (29.4%) at nephritis. Among 8 patients with contrast-enhanced CT at nephritis, one (12.5%) developed bilateral wedge-shaped hypoenhancing cortical. On PET-CT, the renal parenchymal SUVmax-to-blood pool ratio was significantly higher at nephritis compared to baseline (2.13 vs. 1.68; p = 0.035). The renal pelvis SUVmax-to-blood pool SUVmean ratio was significantly lower at nephritis compared to baseline (3.47 vs. 8.22; p = 0.011). CONCLUSIONS: Bilateral increase in kidney size, new/increasing perinephric stranding, and bilateral wedge-shaped hypoenhancing cortical foci can occur in immunotherapy-related nephritis. On PET-CT, a diffuse increase in radiotracer uptake throughout the renal cortex and a decrease in radiotracer activity in the renal pelvis can be seen. KEY POINTS: • CT features of immune checkpoint inhibitor-related nephritis include an increase in kidney volume, new/increasing perinephric stranding, and bilateral ill-defined wedge-shaped hypoenhancing cortical foci. • FDG-PET features of immune checkpoint inhibitor-related nephritis include an increase in FDG uptake throughout the renal cortex and a decrease in FDG activity/excretion in the collecting system. • > 30% increase in total kidney volume is associated with worse toxicity grade and more aggressive medical management.

The Prognostic Value of Baseline Clinical and Radiologic Imaging Features in Patients with Unresectable Hepatocellular Carcinoma Treated with Atezolizumab Plus Bevacizumab.

Purpose: To identify prognostic clinical and radiologic features in patients with unresectable hepatocellular carcinoma (HCC) treated with atezolizumab plus bevacizumab. Patients and Methods: Clinical and imaging records of patients with unresectable HCC were retrospectively reviewed, and baseline features were recorded. Patients' records and imaging studies were used to determine the patients' overall survival (OS) and progression-free survival (PFS). Univariate and multivariate analyses were performed to determine prognostic features. Subanalyses of treatment-naïve patients (who never received local or systemic therapy) and previously treated patients were also performed. Results: Fifty-five patients were included in the final analysis, 23 (41.8%) of whom were treatment naïve. The median PFS and OS for the entire cohort were 3.0 months and 7.9 months. The 3-, 6- and 12-month OS rates were 85.5%, 79.8% and 45.7%, respectively. The 3-, 6- and 12-month PFS rates were 50.1%, 41.2% and 20.1%, respectively. On multivariate analysis, independent prognostic features for poor PFS of the entire cohort were pleural effusions (p = 0.047, HR: 6.3; CI: 1.03-38.90) and hepatic vein tumor thrombus (p = 0.005; HR: 23.37; CI: 2.63-207.67); independent prognostic features for poor OS were ascites (p = 0.008; HR: 37.37; CI: 2.53-467.64), pleural effusion (p = 0.003; HR: 110.17; CI: 5.00-2426.54), and low (<40HU) pre-contrast attenuation on CT images (p = 0.007; HR: 0.09; CI: 0.02-0.53). On subanalysis of treatment-naïve patients, the median OS and PFS were 7.4 months and 2.8 months, respectively. The 3-, 6- and 12-month PFS rates were 43.5%, 38.6% and 24.8%, respectively. Pleural effusion was the only independent poor prognostic feature (p = 0.036; HR: 206.34; CI: 1.41-30,167.58). Conclusion: Independent prognostic features for survival outcomes include the presence of ascites, pleural effusions, hepatic vein tumor thrombus, and HCC with low attenuation (<40 HU) on unenhanced CT images. Although several biochemical variables were significant on univariate analysis, none were independent predictors of OS or PFS.

Increased vein wall thickness in Behçet disease.

OBJECTIVE: Lower extremity (LE) deep venous thrombosis (DVT) is the main feature of vascular involvement in Behçet disease (BD). We thought that vein wall thickness (VWT) could be a surrogate marker for venous inflammation and hence predict future vascular involvement. We assessed VWT in proximal LE veins in BD patients without DVT, BD patients with DVT, and healthy controls in a formal, masked protocol. METHODS: We studied 50 (43 male and 7 female) BD patients with LE DVT (group 1), 50 (43 male and 7 female) BD patients without any vascular involvement (group 2), and 50 (43 male and 7 female) age- and sex-matched apparently healthy controls (group 3). Two radiologists blinded to the diagnosis of BD used ultrasound to measure VWT of common femoral vein, femoral vein, and great saphenous vein in both legs. Interobserver reliability was assessed using the intraclass correlation coefficient and Bland-Altman plots. RESULTS: There was good agreement between the two observers. The mean VWT was significantly increased in both BD patients with LE DVT and those without apparent vascular involvement compared with the healthy controls, whereas those with LE DVT had the highest VWT. CONCLUSIONS: VWT of proximal deep and superficial LE veins is increased among the BD patients without any clinical and radiologic vascular involvement. This information, after prospective work, might be useful in management and elucidating disease mechanisms in vascular BD.