Comparison of 68Ga-FAPI-04 and 18F-FDG PET/CT in Fumarate Hydratase-Deficient Renal Cell Carcinoma: A Prospective and Single-Center Study.

PURPOSE: Fumarate hydratase-deficient renal cell cancer (FHRCC) is a rare and aggressive form of renal cell carcinoma. The diagnostic value of 68Ga-FAPI PET/CT for FHRCC remains unexplored. Therefore, we compared the potential value of 68Ga-FAPI-04 and 18F-FDG PET/CT in FHRCC. PATIENTS AND METHODS: Patients with FHRCC underwent 68Ga-FAPI-04 and 18F-FDG PET/CT from May 2022 to December 2023. The SUVmax and tumor-to-liver ratio (TLR) of both tracers were compared using the Wilcoxon signed rank test. RESULTS: Eleven patients with 83 lesions were enrolled. The rate of 18F-FDG PET/CT in detecting lesions was higher than that of 68Ga-FAPI-04 PET/CT: primary tumors: 75.0% (6/8) versus 50.0% (4/8); lymph nodes: 94.9% (37/39) versus 89.7% (35/39); and bone lesions: 100.0% (21/21) versus 90.5% (19/21). The median SUVmax of primary and metastatic lesions on 18F-FDG PET/CT was comparable to 68Ga-FAPI-04 PET/CT in semiquantitative analysis (primary lesions: 13.86 vs 16.35, P = 1.000; lymph nodes: 10.04 vs 9.33, P = 0.517; bone lesions: 13.49 vs 9.84, P = 0.107; visceral lesions: 8.54 vs 4.20, P = 0.056). However, the median TLRs of primary and metastatic lesions on 68Ga-FAPI-04 PET/CT were higher than that of 18F-FDG PET/CT (primary lesions: 30.44 vs 5.41, P = 0.010; lymph nodes: 17.71 vs 3.95, P = 0.000; bone lesions: 15.94 vs 5.21, P = 0.000; visceral lesions: 9.26 vs 3.44, P = 0.003). CONCLUSIONS: 18F-FDG PET/CT detected more primary and metastatic FHRCC lesions than 68Ga-FAPI-04 PET/CT. However, the higher TLR in FHRCC on 68Ga-FAPI-04 PET/CT may indicate therapeutic potential in targeting fibroblast activation protein in FHRCC.

Primary Hepatocellular Carcinoma Revealed on 68 Ga-DOTATATE in a Patient With Nasopharyngeal Carcinoma.

ABSTRACT: A 56-year-old man underwent a prospective study (ChiCTR2300070081), which is a head-to-head comparison of 18 F-FDG and 68 Ga-DOTATATE PET/MR in EB-positive nonkeratinizing nasopharyngeal carcinoma after chemotherapy. Bilateral cervical abnormal lymph nodes were both detected by 18 F-FDG and 68 Ga-DOTATATE PET/MRI, whereas 2 hepatic lesions only were shown on 68 Ga-DOTATATE, which subsequent pathologically proved to be primary hepatocellular carcinoma.

Comparative Study of Initial Post-Therapeutic 131I Single-Photon Emission Computed Tomography/Computed Tomography and Reoperation for the Detection of Residual Lymph Node Metastasis in Patients With Papillary Thyroid Cancer.

OBJECTIVE: To assess the diagnostic performance of initial post-therapeutic 131I single-photon emission computed tomography/computed tomography (SPECT/CT) compared with that of reoperation in detecting residual lymph node metastasis (LNM). METHODS: Patients with iodine-avid LNM detected on the initial post-therapeutic 131I SPECT/CT and who underwent reoperative dissection within 6 months were included. LNMs (numbers and locations) detected via both methods were compared. The American Thyroid Association dynamic risk stratification was performed for patients receiving second radioactive iodine therapy after reoperation. RESULTS: Fifty-three patients with 95 iodine-avid LNMs detected by 131I SPECT/CT were enrolled. Fifty-one (96.2%) patients had 212 LNMs confirmed by reoperation (P = .004). The sensitivity and specificity of 131I SPECT/CT in detecting LNM were 44.8% (95/212) and 91.6% (87/95), respectively. The location frequency of residual LNMs found by 131I SPECT/CT was similar to that of reoperation (P = .057). Thirty-two patients received a second radioactive iodine treatment, and 6 (18.8%) patients still had residual iodine-avid LNM on SPECT/CT. Therapeutic response was evaluated by American Thyroid Association dynamic risk stratification in 16 patients. The number of patients with structural incomplete response, biochemical incomplete response, indeterminate response, and excellent response was 4 (23.5%), 4 (23.5%), 5 (29.4%), and 3 (17.6%), respectively. CONCLUSION: 131I SPECT/CT has high specificity but relatively low sensitivity in detecting all residual LNMs. Approximately 80% of patients were rendered structurally disease free after reoperation.

Radioactive Iodine-Refractory Pulmonary Metastases of Papillary Thyroid Cancer in Children, Adolescents, and Young Adults.

CONTEXT: Few studies have explored radioactive iodine-refractory (RAIR) disease in children, adolescents, and young adults with papillary thyroid cancer (CAYA-PTC). OBJECTIVE: This study systematically investigated the clinicopathologic characteristics and prognosis of CAYA-PTC with RAIR disease. METHODS: Sixty-five patients with PTC aged ≤20 years were enrolled in this study, and all patients were confirmed to have pulmonary metastases. Clinicopathologic profiles were compared between the radioactive iodine-avid (RAIA) and RAIR groups. Univariate and multivariate regression analyses were performed to identify risk factors for RAIR status and progressive disease (PD). Gene alterations were detected in 17 patients. RESULTS: Overall, 20 patients were included in the RAIR group, accounting for 30.8% (20/65) of all patients. No significant difference in pathologic characteristics was observed between patients aged <15 years and patients aged 15-20 years, but younger patients were more likely to develop RAIR disease (hazard ratio [HR] 3.500, 95% CI 1.134-10.803, P = .023). RET fusions were the most common genetic alterations in CAYA-PTC, but an association with RAIR disease was not detected (P = .210). RAIR disease (HR 10.008, 95% CI 2.427-41.268, P = .001) was identified as an independent predictor of PD. The Kaplan-Meier curve revealed a lower progression-free survival (PFS) and disease-specific survival (DSS) rate in the RAIR group than in the RAIA group (P < .001 and P = .039). Likewise, RAIR disease was a risk factor for unfavorable PFS in patients aged <15 years (P < .001). CONCLUSION: RAIR disease occurs in one-third of CAYA-PTC with pulmonary metastases. Younger patients (aged < 15 years) are more susceptible to RAIR status, which leads to unfavorable PFS and DSS.

Positive BRAFV600E mutation of primary tumor influences radioiodine avidity but not prognosis of papillary thyroid cancer with lung metastases.

Purpose: This study investigated the relationship between BRAFV600E mutation of the primary tumor and radioiodine avidity in lung metastases (LMs) and then further evaluated the impact of BRAFV600E mutation and radioiodine avidity status on the prognosis of papillary thyroid cancer (PTC) with LMs. Methods: Ninety-four PTC patients with LMs after total thyroidectomy and cervical lymph node dissection between January 2012 and September 2021 were retrospectively included. All patients received BRAFV600E mutation examination of primary tumors and radioactive iodine (RAI) therapy. The therapeutic response was evaluated by Response Evaluation Criteria in Solid Tumors (RECIST) assessments (version 1.1). For patients with target lesions, the response was divided into complete response (CR), partial response (PR), stable disease (SD), and progressive disease (PD); for patients without target lesions, the response was divided into CR, non-CR/non-PD, and PD. In therapeutic response, PR and SD were classified as non-CR/non-PD for analysis. The chi-square test and logistic regression were used to analyze the impact factor on PD and mortality. Progression-free survival (PFS) and overall survival (OS) curves were constructed by the Kaplan-Meier method. Results: It was found that 21.2% (7/33) of patients with positive BRAFV600E mutation and 62.3% (38/61) of patients with negative BRAFV600E mutation had radioiodine-avid LMs (χ2 = 14.484, p = 0.000). Patients with positive BRAFV600E mutation are more likely to lose radioiodine avidity; the odds ratios (ORs) were 5.323 (95% CI: 1.953-14.514, p = 0.001). Finally, 25 patients had PD, and six patients died; loss of radioiodine avidity was the independent predictor for PD, and the ORs were 10.207 (95% CI: 2.629-39.643, p = 0.001); BRAFV600E mutation status was not correlated with PD (p = 0.602), whether in the radioiodine avidity group (p = 1.000) or the non-radioiodine avidity group (p = 0.867). Similarly, BRAFV600E mutation status was not correlated with mortality; only loss of radioiodine avidity was the unfavorable factor associated with mortality in univariate analyses (p = 0.030). Conclusion: Patients with LMs of PTC were more likely to lose radioiodine avidity when their primary tumor had positive BRAFV600E mutation; however, only radioiodine avidity and not BRAFV600E mutation status affected the clinical outcome of patients with lung metastatic PTC.