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Purpose: This study investigates the prognostic value of 68 Ga-Pentixafor PET/CT using PET-derived quantitative in multiple myeloma (MM) patients with suspected recurrence in comparison to 18 F-FDG PET/CT and clinical data., Methods: Twenty-four MM patients with suspicion for relapse who underwent 68 Ga-Pentixafor and 18 F-FDG PET/CT were retrospectively evaluated. Total bone marrow glycolysis for 18 F-FDG (TBM FDG ) and total bone marrow uptake for 68 Ga-Pentixafor PET/CT (TBM CXCR4 ) were calculated using whole-body metabolic tumor burden obtained by dedicated software (MIM 7.0.6). The patients were followed for 19-24 months, and the association of PET-derived quantitative data with overall survival (OS) was analyzed., Results: 68 Ga-Pentixafor PET/CT was positive in 17 patients, of which 13 were also positive on 18 F-FDG PET/CT, whereas 7 patients were negative on both scans. The positive rate of 68 Ga-Pentixafor and 18 F-FDG PET/CT on a patient-based approach was 70.8% and 54.1%, respectively. 68 Ga-Pentixafor positivity was significantly associated with OS (p = 0.009), and 18 F-FDG positivity was at the margin of statistical significance (p = 0.056). TBM CXCR4 and TBM FDG were negatively correlated with OS (r = -0.457, p = 0.025 and r = -0.617, p = 0.001, respectively). The OS was negatively correlated with beta-2-microglobulin levels (r = -0.511, p = 0.01) and CRAB score (r = -0.592, p = 0.002) as an indicator of the end-organ disease, which confirmed these results. Serum beta-2-microglobulin levels and CRAB score were also correlated with TBM CXCR4 (r = 0.442, p = 0.039 and r = 0.573, p = 0.003, respectively) and TBM FDG (r = 0.543, p = 0.009 and r = -0.424, p = 0.003, respectively)., Conclusion: 68 Ga-Pentixafor PET/CT positivity is a negative prognostic factor in the survival outcome of MM patients. Complementary 68 Ga-Pentixafor PET/CT has the potential to overcome 18 F-FDG PET/CT limitations and helps a more precise risk stratification., (© 2021. The Japanese Society of Nuclear Medicine.)

Purpose: We investigated the role of PSMA-derived tumor burden in predicting docetaxel (DTX) therapy response in metastatic castration-resistant prostate cancer (mCRPC)., Methods: Fifty-two mCRPC patients who received at least six cycles of DTX as the first-line treatment following 68 Ga-PSMA PET/CT were enrolled in this retrospective study. Total PSMA-derived tumor volume (TV-PSMA) and total lesion PSMA activity (TL-PSMA) were derived from metastatic lesions. A ≥ 50% decline in PSA was defined as a response; a ≥ 25% increase in PSA was defined as progression. Univariate/multivariate logistic and cox regression analyses were performed to predict PSA response, OS, and TTP., Results: Twelve (23%) patients had PSA progression after chemotherapy, while 40 patients (77%) achieved a PSA response. On univariate analysis, a significant association was found between TV-PSMA (p = 0.001), TL-PSMA (p = 0.001), pre-PSA (p = 0.012), LDH (p = 0.003), Hg (p = 0.035), and PSA response to DTX. High TV-PSMA (> 107 cm 3 ) (p = 0.04) and high LDH (> 234 U/L) (p = 0.017) were 8.2 times and 12.2 times more likely for DTX failure in multivariate regression analyses. The median TTP was 16 months, and the median OS was not reached. Patients with high TV-PSMA (p = 0.017), high TL-PSMA (> 1013 cm 3 ) (p = 0.042), high age (> 70 years) (p = 0.016), and high LDH (p ≤ 0.001) had significantly shorter OS, while only high TV-PSMA (p = 0.038) and high age (p = 0.006) were significantly related with shorter TTP. High TV-PSMA (p = 0.017) and high age (p = 0.01) were significant predictors for shorter OS, while only high age (p = 0.006) was a significant predictor for shorter TTP in multivariate analysis., Conclusion: Patients with high TV-PSMA had a significantly higher risk for DTX failure. PSMA-based tumor burden prior to DTX therapy seems to be a reliable predictive tool for survival in mCRPC patients.

Objective: This study sets out to evaluate patients with increased uptake in breast lesions on 68 Ga-DOTATATE PET/CT (DOTA PET) and determine the clinical significance of somatostatin receptor (SSTR) positive breast lesions., Methods: We retrospectively evaluated all patients with increased SSTR uptake in breast lesions on DOTA PET. Patients with physiological (e.g., lactation) or normal variant breast uptake (e.g., mild diffuse glandular uptake) were excluded. The maximum standard uptake value (SUVmax) was calculated using a manually drawn region of interest in the most intense uptake of breast lesions. All lesions were correlated with breast imaging, including mammography and ultrasonography. Histopathological correlation was performed if the lesion was suspicious for malignancy. Lesions were followed up radiologically (1-8 years)., Results: Out of 1573 retrospectively analyzed DOTA PET scans, the incidence of SSTR + breast lesions was measured as 1.1% (n = 18); however, 4 of 18 patients were excluded due to the lack of final diagnosis of lesions. The median age was 35 (range 14-58 years), and all patients were female. The median SUVmax of SSTR + breast lesions was 5.2 (range 1.5-12.6) for a total of 14 patients. Twelve patients had a single SSTR + breast lesion, while 2 patients had multiple SSTR + lesions on bilateral breasts. In 6 patients, single SSTR + lesions were considered as fibroadenoma; in 2 patients, multiple SSTR + lesions were considered as metastases of NET, based on correlative breast imaging. In 6 patients, histopathological confirmation was needed for the final diagnosis. Histopathologic findings confirmed fibroadenoma in 4 patients by biopsy, in 1 patient with surgical removal of the lesion. The last patient who had a history of IDC was diagnosed with a recurrence of IDC with biopsy. The median SUVmax was 5.1 (range 1.5-9.4) for malignant breast lesions and 5.4 (range 2.2-12.6) for benign breast lesions., Conclusion: SSTR + breast lesions on DOTA PET are rarely seen in clinical practice. Uptakes of breast lesions in our cases were variable and not useful for differential diagnosis of lesions. It seems that SSTR + breast lesions should be evaluated with clinical and radiological characteristics, and correlative breast imaging and/or histopathological verification should be performed for suspicious lesions to avoid misdiagnosis.