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Purpose: To evaluate the added value of additional 68Ga-FAPI PET/CT following CT for primary staging, detection of postoperative recurrence, and management of gastric cancer patients. Methods: We retrospectively included patients with gastric cancers who underwent contrast-enhanced computed tomography (ceCT), followed by 68Ga-FAPI PET/CT within 30 days. 68Ga-FAPI PET/CT was performed for initial staging or detection of postoperative recurrence. Two nuclear medicine physicians and a radiologist independently decided on imaging-based staging. Pre-68Ga-FAPI PET/CT treatment decisions were made by a simulated tumor board and post-68Ga-FAPI PET/CT decisions were extracted from medical records. We evaluated the impact of 68Ga-FAPI PET/CT with inconsistent new findings based on the initial findings from ceCT and the resulting changes in treatment strategies. Results: We included 112 patients, 84 for initial staging and 28 for detection of postoperative recurrence. Compared to CT, 29 new findings in 24 patients were diagnosed as, or ruled out, cancer involvement on 68Ga-FAPI PET/CT. Among the 112 patients, 21 patients (18.8%) experienced changes in stage or postoperative recurrence. Among patients for initial staging, 14 had stage changes, with 10 being upstaged and 4 being downstaged. Among patients for detection of postoperative recurrence, 7 more patients were diagnosed with tumor recurrence. New findings of 68Ga-FAPI PET/CT led to treatment change in 20/112 (17.9%) patients, which was deemed of major change in 19 patients and minor change in 1 patient. Conclusions: 68Ga-FAPI PET/CT is valuable for precise staging and detection of postoperative recurrence of gastric cancers, and has the potential to influence management. [ABSTRACT FROM AUTHOR]

Objective: This study aimed to ascertain the diagnostic efficacy of routine 68Ga-PSMA imaging conducted 1 h post-injection, in conjunction with delayed imaging performed 3 h post-injection, for differentiating between benign and malignant lesions in prostate cancer (PCa) patients. Methods: A retrospective assessment was undertaken on 44 prostate cancer patients who had undergone both routine and delayed 68Ga-PSMA PET/CT scans. Variations in SUVmax and SUVmean values in normal organs, primary prostate cancer sites, metastatic sites, and benign lesions were analyzed. Pathological examination and extended follow-ups were used to confirm all lesions. Results: The study encompassed 44 patients, presenting 35 primary prostate cancer lesions, 44 metastatic lesions, and 30 benign lesions. Delayed imaging (3 h post-injection) demonstrated a decreasing trend in the SUVmax and SUVmean for the liver, blood, and spleen. Conversely, an increasing trend was observed for the parotid, lacrimal, and submandibular glands. For primary lesions, the SUVmax and SUVmean values were 17.63 ± 9.61 and 9.77 ± 5.18 during routine imaging, and 25.09 ± 15.11 and 14.05 ± 8.02 (P < 0.001) during delayed imaging. A comparable increase in SUVmax and SUVmean was seen in the delayed images for metastatic lesions when juxtaposed with routine images. Nevertheless, benign lesions displayed a decrease in SUVmax and SUVmean during delayed imaging when set against routine imaging (SUVmax: 3.56 ± 1.49 vs 2.93 ± 1.47, P = 0.001; SUVmean: 1.99 ± 0.87 vs 1.65 ± 0.87, P = 0.003). Conclusion: Imaging using 68Ga-PSMA PET/CT at 3 h post-injection manifested a higher uptake and target-to-background uptake in most malignant prostate cancer lesions, but a diminished uptake in benign lesions. This observation can assist clinicians in distinguishing non-specific PSMA uptake in prostate cancer patients based on PSMA PET/CT image. [ABSTRACT FROM AUTHOR]

During the initial staging of certain lymphoma subtypes, 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) has become an alternative to bone marrow biopsy (BMB) for detecting bone marrow (BM) involvement. However, whether [18F]FDG-PET/CT can accurately detect BM involvement in angioimmunoblastic T-cell lymphoma (AITL) remains unknown. Our study aimed to assess the diagnostic and prognostic capability of [18F]FDG-PET/CT for detecting BM involvement in AITL. Methods: This retrospective study included 84 individuals newly diagnosed with AITL who underwent baseline BMB and [18F]FDG-PET/CT. "BM involvement" was defined as one or both of the following: 1) angioimmunoblastic T-cells detected in the BM; or 2) initially heightened focal uptake having disappeared on follow-up [18F]FDG-PET/CT. The ability of [18F]FDG-PET/CT to detect BM cancerous lesions was respectively analyzed by BM involvement confirmed by BMB or the aforementioned definition as the reference standard. The patients' clinical characteristics and survival and prognostic outcomes were respectively analyzed. Of the 84 participants, five (6.0%) displayed positive BMB and PET/BM results, 17 (20.2%) had BMB-positive but PET/BM-negative results, eight (9.5%) showed BMB-negative but PET/BM-positive outcomes, and 54 (64.3%) displayed negative BMB and PET/BM outcomes. Using pre-defined BM involvement as the reference standard, [18F]FDG-PET/CT exhibited a specificity of 100%, sensitivity of 40%, negative predictive value (NPV) of 75%, and positive predictive value (PPV) of 100%. In contrast, using BMB-detected BM involvement as reference, [18F]FDG-PET/CT exhibited a sensitivity, specificity, PPV, and NPV of 38.5%, 76.1%, 22.7%, and 87.1%, respectively. Among patients with PET/BM-positive and BMB-negative outcomes, 62.5% (5/8) underwent upstaging from III to IV. In 58.8% (10/17) of patients who were initially diagnosed with stage II/III disease based on the [18F]FDG-PET/CT results, repeat BMB resulted in upstaging to IV. PET/BM-negative patients had a higher 3-year progression-free survival rate (38.3% vs. 22.8%, p = 0.018) and 3-year overall survival rate (64.4% vs. 34.6%, p = 0.011) than PET/BM-positive patients. In AITL patients, PET/BM-positive results may obviate the necessity for repeat BMB to ascertain confirm BM involvement. PET/BM-negative results do not definitively exclude BM involvement. The combined use of [18F]FDG-PET/CT and BMB can increase the diagnostic accuracy of BM involvement for AITL patients. [ABSTRACT FROM AUTHOR]

Interim 18F-FDG PET/CT (I-PET) has a role in response evaluation and treatment guidance in patients with nasal-type extranodal natural killer/T cell lymphoma (ENKTL). However, there was no agreement on the timing of I-PET performed, after chemotherapy or after chemoradiotherapy. We aimed to find the appropriate timing for I-PET by assessing the prognostic value of I-PET in response evaluation in ENKTL patients. Two hundred and twenty-seven ENKTL patients who had undergone I-PET were retrospectively included. All patients were grouped based on their therapeutic strategy received, chemotherapy or chemoradiotherapy. The Deauville 5-point score (DS) was used to interpret the I-PET images. The hazard ratio (HR) and C-index were used to measure the discriminatory and prognostic capacities of I-PET performed at different times. One hundred and six patients underwent the I-PET after chemotherapy (chemotherapy group), while I-PET was performed after chemoradiotherapy in 121 patients (chemoradiotherapy group). Eighty-seven patients were classified as metabolic remission (DS score of 1–3), while the other 140 were classified as non-metabolic remission (DS score of 4–5) according to the Deauville criteria. There were no significant survival differences between patients in metabolic remission and in non-metabolic remission in either progression-free survival (PFS, p = 0.406) or overall survival (OS, p = 0.350). In the chemotherapy group, patients in metabolic remission had significantly superior PFS than patients in non-metabolic remission (p = 0.012). For OS, a discriminative trend was also found on the survival curve between patients in metabolic remission and in non-metabolic remission (p = 0.082). In the chemoradiotherapy group, there was no significant difference in PFS (P = 0.185) or OS (P = 0.627) between patients in metabolic remission and in non-metabolic remission. I-PET after chemotherapy yields higher discriminative power and has the ability for prognostic prediction in nasal-type ENKTL patients. I-PET after radiochemotherapy has no prognostic value. Thus, the appropriate timing for I-PET is after chemotherapy but before radiotherapy for response evaluation in nasal-type ENKTL patients. [ABSTRACT FROM AUTHOR]

Purpose: Gallium 68 (68Ga)-labeled fibroblast activation protein inhibitor (FAPI) PET/CT is sensitive on breast cancer staging, but its clinical utility may be limited by the high physiological 68Ga-FAPI-04 uptake in normal breast tissue that can obscure primary tumors. The aim of this study was to elucidate the characteristics of physiological 68Ga-FAPI-04 uptake in normal breast. Procedures: A total of 143 consecutive women with 68Ga-FAPI-04 PET/CT data were reviewed retrospectively. SUVmax, density and thickness of breast, as well as SUVmax of nipple, were measured. Univariate and multivariate regression analyses were used to identify factors related to the breast and nipple SUVs. Results: Twenty-eight premenopausal, 62 menopausal and 10 post-operative (after bilateral adnexectomy) women with 103 examinations were included. All had a diffuse, symmetrical uptake in breast. There was no difference in 68Ga-FAPI-04 uptake between bilateral breasts (right: median, 1.14[IQR, 0.85–1.54] vs. left: median, 1.09[IQR, 0.86–1.54]; P = 0.253). Patients in menstrual status with expected high estrogen level (late follicular, ovulatory and mid luteal phases) had higher breast SUVs (median SUV, 3.91 [IQR, 2.85–4.35]) than those with expected moderate (early follicular, early luteal and late luteal phases; median SUV, 1.57 [IQR, 1.39–2.08]; P < 0.001) or low level (menopause and post-operation; median SUV, 0.98 [IQR, 0.83–1.21]; P < 0.001). Menstrual status was an independent predictors of breast SUV (r2 = 0.689, P < 0.001). All the patients had a focal, symmetrical uptake in nipples. Nipple SUV did not correlate with menstrual status (P = 0.913). [ABSTRACT FROM AUTHOR]