Head-to-head comparison of 18F-FDG and 18F-FES PET/CT for initial staging of ER-positive breast cancer patients.

PURPOSE: To compare the diagnostic performance of 18F-fluorodeoxyglucose (18F-FDG) and 18F-fluoroestradiol (18F-FES) positron emission tomography/computed tomography (PET/CT) for initial staging of estrogen receptor (ER) positive breast cancer. METHODS: Twenty-eight patients with ER-positive breast cancer underwent 18F-FDG and 18F-FES PET/CT for initial staging. Diagnostic performance and concordance rates were analyzed for both radiotracers. Semiquantitative parameters of maximum standardized uptake value (SUVmax) and tumor-to-normal ratio (T/N ratio) were compared using Wilcoxon signed-rank test. Factors potentially affecting the degree of radiotracer uptake were analyzed by multi-level linear regression analysis. RESULTS: The overall diagnostic performance of 18F-FES was comparable to 18F-FDG, except for higher specificity and NPV, with sensitivity, specificity, PPV, NPV, and accuracy of 87.56%, 100%, 100%, 35.14%, and 88.35%, respectively, for 18F-FES and 83.94%, 30.77%, 94.74%, 11.43%, and 95.37%, respectively, for 18F-FDG. Diagnostic performance of strong ER expression was better in 18F-FES but worse for 18F-FDG. There was a correlation of mucinous cell type and Allred score 7-8 with 18F-FES uptake, with correlation coefficients of 26.65 (19.28, 34.02), 5.90 (- 0.005, 11.81), and p-value of < 0.001, 0.05, respectively. Meanwhile, luminal B and Ki-67 were related to 18F-FDG uptake, with correlation coefficients of 2.76 (1.10, 0.20), 0.11 (0.01, 0.2), and p-value of 0.018, 0.025, respectively. CONCLUSION: Diagnostic performance of 18F-FES is comparable to 18F-FDG, but better for strongly ER-positive breast cancer. Combination of 18F-FES and 18F-FDG would potentially overcome the limitations of each tracer with more accurate staging.

Comparisons of Quantitative Parameters of Ga-68-Labelled Fibroblast Activating Protein Inhibitor (FAPI) PET/CT and [18F]F-FDG PET/CT in Patients with Liver Malignancies.

PURPOSE: To compare quantitative parameters and tumour detection rates of [68 Ga]Ga-FAPI PET/CT with those of dedicated liver PET/MRI and 18F-FDG PET in patients with liver malignancies. PROCEDURES: Twenty-seven patients (29 imaging studies) with diagnosed or suspected liver malignancies who underwent [68 Ga]Ga-FAPI-46 PET/CT, liver PET/MRI, and [18F]FDG PET/CT between September 2020 and June 2021 were retrospectively analysed. MRI findings were used as the reference standard for diagnosis. RESULTS: The 27 patients had a median age of 68 years (interquartile range: 60-74 years; 21 men). Primary intrahepatic tumours were reported in 13 patients (15 imaging studies) with cholangiocarcinoma (CCA) and in 14 patients with hepatocellular carcinoma (HCC). All intrahepatic lesions detectable on MRI were also detected on [68 Ga]Ga-FAPI-46 PET/CT giving a sensitivity of 100% (19/19), whereas the sensitivity of [18F]FDG PET/CT was 58% (11/19). All intrahepatic lesions were detected on [68 Ga]Ga-FAPI-46 PET/CT, on which they showed higher activity (median SUVmax: 15.61 vs. 5.17; P < .001) and higher target-to-background ratio (TBR; median, 15.90 vs. 1.69, P < .001) than on [18F]FDG, especially in patients with CCA (median TBR, 21.08 vs. 1.47, respectively; P < .001). The uptake positivity rate in regional node metastasis was 100% (12/12) on [68 Ga]Ga-FAPI-46 PET/CT compared with 58% (7/12) on [18F]FDG PET/CT. All patients with distant metastasis (100%, 14/14) were detected on both [18F]FDG and [68 Ga]Ga-FAPI-46 PET/CT imaging, although more distant metastatic lesions were detected on [68 Ga]Ga-FAPI-46 PET/CT than on [18F]FDG (96% (42/44) vs. 89% (39/44), respectively). CONCLUSION: [68 Ga]Ga-FAPI PET/CT with dedicated liver PET/MRI shows potential for superior detection of hepatic malignancy compared with [18F]FDG PET/CT or MRI alone.

Clinical impact of quantitative [15O] H2O PET/CT myocardial perfusion imaging on decision-making regarding invasive management of coronary artery disease.

BACKGROUND: This study was performed to determine the impact of oxygen-15-labeled water ([15O] H2O) positron emission tomography/computed tomography (PET/CT) myocardial perfusion imaging (MPI) on referral for invasive coronary angiography (ICA) and revascularization. METHODS: This study involved 57 patients who underwent [15O] H2O PET/CT MPI for evaluation of coronary artery disease (CAD). Data of referral for ICA and revascularization, clinical symptoms, and cardiac events within 6 months after MPI were assessed. Logistic regression was used to determine the predictors for referral and revascularization. The diagnostic values of hyperemic myocardial blood flow (MBF) and coronary flow reserve (CFR) were calculated. RESULTS: Normal and abnormal MPI findings were observed in 18 (32%) and 39 (68%) patients, respectively. The referral rate was significantly different between the normal and abnormal MPI groups (5.6% and 48.7%, respectively; P = .002). Revascularization rate of abnormal MPI group was 40.0%. There were significant differences of hyperemic MBF and CFR between patients with and without referral. Hyperemic MBF was significant predictor for referral (OR 15.24, 95% CI 3.39-68.55, P < .005) and revascularization (OR 28.57, 95% CI 3.08-265.33, P < .005). CONCLUSION: [15O] H2O PET/CT MPI showed a clinical impact on decision-making regarding invasive procedure for management of CAD.

Head-to-Head Comparison of 68Ga-FAPI-46 and 18F-FDG PET/CT for Evaluation of Head and Neck Squamous Cell Carcinoma: A Single-Center Exploratory Study.

68Ga-conjugated fibroblast activation protein inhibitor (68Ga-FAPI) has become an attractive agent for PET. This study aimed to compare 68Ga-FAPI-46 PET/CT with 18F-FDG PET/CT for detecting primary cancer and metastatic lesions in patients with head and neck squamous cell carcinoma (HNSCC). Methods: Twelve patients and 28 patients with HNSCC underwent 68Ga-FAPI-46 and 18F-FDG PET/CT for initial staging and recurrence detection, respectively. The concordance and diagnostic accuracy of both tracers were analyzed. Semiquantitative parameters, including SUVmax, SUVmean, and tumor-to-background ratio, were compared. Fibroblast activation protein (FAP) expression tumor volume and total lesion FAP expression of 68Ga-FAPI-46 were compared with metabolic tumor volume and total lesion glycolysis of 18F-FDG, respectively. Differences between semiquantitative parameters were analyzed using paired t testing. Results:68Ga-FAPI-46 PET/CT was 83.3% and 96.4% concordant with 18F-FDG PET/CT for initial staging and recurrence detection, respectively. Eighteen lesions had histopathologic validation, and both tracers displayed 100% sensitivity, 50% specificity, and 94.4% accuracy for lesion-based analysis. FAP expression tumor volume was greater than metabolic tumor volume (P < 0.05), but no significant differences were observed for the other parameters. Conclusion:68Ga-FAPI-46 PET/CT showed good concordance with, and comparable diagnostic performance to, 18F-FDG PET/CT for initial staging and recurrence detection in HNSCC patients.

The Evaluation of Tau Deposition with [18F]PI-2620 by Using a Semiquantitative Method in Cognitively Normal Subjects and Patients with Mild Cognitive Impairment and Alzheimer's Disease.

Background: Some studies have reported the effectiveness of [18F]PI-2620 as an effective tau-binding radiotracer; however, few reports have applied semiquantitative analysis to the tracer. Therefore, this study's aim was to perform a semiquantitative analysis of [18F]PI-2620 in individuals with normal cognition and patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Methods: Twenty-six cognitively normal (CN) subjects, 7 patients with AD, and 36 patients with MCI were enrolled. A dynamic positron emission tomography (PET) scan was performed 30-75 min postinjection. PET and T1-weighted magnetic resonance imaging scans were coregistered. The standardized uptake value ratio (SUVr) was used for semiquantitative analysis. The P-Mod software was applied to create volumes of interest. The ANOVA and post hoc Tukey HSD were used for statistical analysis. Results: In the AD group, the occipital lobe had a significantly higher mean SUVr (1.46 ± 0.57) than in the CN and MCI groups. Compared with the CN group, the AD group showed significantly higher mean SUVr in the fusiform gyrus (1.06 ± 0.09 vs. 1.49 ± 0.86), inferior temporal (1.07 ± 0.07 vs. 1.46 ± 0.08), parietal lobe, lingual gyrus, and precuneus regions. Similarly, the AD group demonstrated a higher mean SUVr than the MCI group in the precuneus, lingual, inferior temporal, fusiform, supramarginal, orbitofrontal, and superior temporal regions. The remaining observed regions, including the striatum, basal ganglia, thalamus, and white matter, showed a low SUVr across all groups with no statistically significant differences. Conclusion: A significantly higher mean SUVr of [18F]PI-2620 was observed in the AD group; a significant area of the brain in the AD group demonstrated tau protein deposit in concordance with Braak Stages III-V, providing useful information to differentiate AD from CN and MCI. Moreover, the low SUVr in the deep striatum and thalamus could be useful for excluding primary tauopathies.

Evaluation of Imaging Windows for Tau PET Imaging Using 18F-PI2620 in Cognitively Normal Individuals, Mild Cognitive Impairment, and Alzheimer's Disease Patients.

BACKGROUND: The study aimed to evaluate the appropriate uptake-timing in cognitively normal individuals, mild cognitive impairment (MCI), and Alzheimer's disease (AD) patients, using 18F-PI 2620 dynamic PET acquisition. METHODS: Thirty-four MCI patients, 6 AD patients, and 24 cognitively normal individuals were enrolled in this study. A dynamic 18F-PI 2620 PET study was conducted at 30-75 minutes post-injection in these groups. Co-registration was applied between the dynamic acquisition PET and T1-weighted MRI to delineate various cortical regions. The standardized uptake value ratio (SUVR) was used for quantitative analysis. P-mod software with the Automated Anatomical Labeling (AAL)-merged atlas was employed to generate automatic volumes of interest for 11 brain regions. RESULTS: The curves in most brain regions presented an average SUVR stability at 30-40 minutes post-injection in each group. The appropriate uptake-timing interval of 18F-PI 2620 was 30-75 minutes post injection for AD group and 30-40 minutes post injection for both cognitively normal individuals and MCI groups. CONCLUSION: Short uptake time around 30-40 minutes post-injection would be more comfortable and convenient for all patients, especially in those with dementia who were unable to stay motionless for long periods of scanning time in the scanner.