This study was designed to analyze the safety, biodistribution, and radiation dosimetry of a gastrin-releasing peptide receptor (GRPR) antagonist PET tracer, Ga-RM26; to assess its clinical diagnostic value in prostate cancer patients; and to perform a direct comparison between GRPR antagonist Ga-RM26 and agonistGa-BBN. Five healthy volunteers were enrolled to validate the safety ofGa-RM26 and calculate dosimetry. A total of 28 patients with prostate cancer (17 newly diagnosed and 11 posttherapy) were recruited and provided written informed consent. All the cancer patients underwent PET/CT at 15-30 min after intravenous injection of 1.85 MBq (0.05 mCi) per kilogram of body weight of Ga-RM26. Among them, 22 patients (11 newly diagnosed and 11 posttherapy) underwentGa-BBN PET/CT for comparison within 1 wk. Tc-MDP (methylene diphosphonate) bone scans were obtained within 2 wk for comparison. GRPR immunohistochemical staining of tumor samples was performed. The administration of Ga-M26 was well tolerated by all subjects, with no adverse symptoms being noticed or reported during the procedure and at 2-wk follow-up. The total effective dose equivalent and effective dose were 0.0912 ± 0.0140 and 0.0657 ± 0.0124 mSv/MBq, respectively. In the 17 patients with newly diagnosed prostate cancer,Ga-RM26 PET/CT showed positive prostate-confined findings in 15 tumors with an SUV of 6.49 ± 2.37. In the 11 patients who underwent prostatectomy or brachytherapy with or without androgen deprivation therapy, Ga-RM26 PET/CT detected 8 metastatic lymph nodes in 3 patients with an SUV of 4.28 ± 1.25 and 21 bone lesions in 8 patients with an SUV of 3.90 ± 3.07. Compared with Ga-RM26 PET/CT, GRPR agonistGa-BBN PET/CT detected fewer primary lesions and lymph node metastases as well as demonstrated lower tracer accumulation. There was a significant positive correlation between SUV derived from Ga-RM26 PET and the expression level of GRPR ( < 0.001). This study indicates the safety and significant efficiency of GRPR antagonistGa-RM26. Ga-RM26 PET/CT would have remarkable value in detecting both primary prostate cancer and metastasis.Ga-RM26 is also expected to be better than GRPR agonist as an imaging marker to evaluate GRPR expression in prostate cancer.

Background:Pulmonary carcinoids (PC) are histologically classified into typical carcinoid (TC) and atypical carcinoid (AC). The diagnosis of pulmonary carcinoid and possibly the differentiation between TC and AC could make a significant effect on the treatment planning as well as prognosis.[1] Several studies have explored the utility of 68Ga-DOTA-Peptide (68Ga-labelled [1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid]-peptide) and 18F-flurodeoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) in the evaluation of primary pulmonary carcinoids. Therefore, we performed a meta-analysis to evaluate the diagnostic accuracy and prediction efficiency of histological subtypes of these two imaging modalities in primary PC.Methods:Relevant studies were identified by searching PubMed, Web of Science, and EMBASE published from 2006 to 2016. Two authors extracted characteristics of patients and their lesions using predefined criteria.Results:Fourteen studies comprising 352 patients were included in this meta-analysis. The pooled sensitivity of 68Ga-DOTA-Peptide and 18F-FDG PET/CT in detecting pulmonary carcinoid were 90.0% (95% CI = 82.0–95.0%; P = .07; I2 = 49.6%) and 71.0% (95% CI = 66.0–76.0%; P < .001; I2 = 59.3%), respectively. An SUVmax ratio between 68Ga-DOTA-Peptide and 18F-FDG higher than the cutoff value of 4.28 was predictive of TC with 89.3% sensitivity and 100% specificity (AUC, 96.4%; 95% CI, 91.1–100%). The ratio of tumor uptake to atelectatic lung uptake was significantly higher for 68Ga-DOTA-peptide (2.5–91, mean 30.5 ± 28.1) than for 18F-FDG (0.3–10.3, mean 2.1 ± 2.3) (P < .001).Conclusions:Both 68Ga-DOTA-peptide and 18F-FDG are highly sensitive in detecting pulmonary carcinoid, while 68Ga-DOTA-peptide is more sensitive than 18F-FDG (90.0% vs 71.0%). The SUVmax ratio was an accurate predictor of the histopathologic variety of the carcinoid tumor, and 68Ga-DOTA-peptide was better than 18F-FDG in cases with atelectasis.

Objectives The objective of this study was to assess and compare the performance of 68Ga-DOTA-conjugated-somatostatin-receptor-targeting-peptides (68Ga-DOTA-SST) PET/CT, octreoscan-SPECT/CT and 18F-FDG-PET/CT in the detection of tumor-induced osteomalacia (TIO). Methods Relevant studies reporting the performance 68Ga-DOTA-SST PET/CT, octreoscan-SPECT/CT and 18F-FDG-PET/CT in TIO were identified by searching PubMed, EMBASE, and Web of Science (last updated June 2019). Two authors independently extracted the numbers of true and false positives, and true and false negatives. The pooled estimates on a per-patient basis were calculated with 95% confidence interval (CI) obtained using a random-effects model. Results Fourteen studies comprising 346 patients were included in this meta-analysis. The meta-analysis provided the following results on a per-patient analysis. The pooled sensitivities of both 68Ga-DOTA-SST PET/CT (90%, 95% CI 82–95%) and octreoscan-SPECT/CT (83%, 95% CI 75–89%) were found to be significantly higher (P < 0.005) than that of 18F-FDG PET/CT (67%, 95% CI 53–80%). There was no statistically significant difference between the sensitivity of 68Ga-DOTA-SST PET/CT and octreoscan-SPECT/CT (P = 0.161). Owing to the low number of articles with true negative findings, the pooled specificities were not calculated. A total of 287 tumors were identified in 287 patients according to the data the included studies offered. The majority of the tumors were located in the lower extremities (59.6%, 171/287), followed by craniofacial regions (24.0%, 69/287), torso (9.4%%, 27/287), and upper extremities (6.9%, 20/287). Conclusion This meta-analysis demonstrates that somatostatin receptor-based imaging modalities outperformed 18F-FDG PET/CT in the detection of TIO, with 68Ga-DOTA-SST PET/CT performing slightly better than octreoscan-SPECT/CT.

The aim of this study was to investigate the value of multiple parameters retrieved from the FDG PET/CT studies, including SUVmax, SUVmean, SUVpeak, MTV, TLG, tumour size in differentiating retroperitoneal paragangliomas from UCD. 28 patients with solitary retroperitoneal masses who had undergone preoperative 18 F-FDG PET/CT were retrospectively evaluated. Histopathology by surgical resection confirmed 17 paragangliomas and 11 UCDs. SUVmax, SUVmean, SUVpeak, MTV, TLG, and tumour size of 18 F-FDG PET/CT were measured for each patient. Mann–Whitney U-test was used to assess differences in multiple parameters between paragangliomas and UCDs. The ROC curve analysis was performed to determine the differential diagnostic value of these parameters. Paragangliomas presented significantly higher SUVmax ( P < 0.001), SUVmean ( P = 0.001), SUVpeak ( P < 0.001), and TLG ( P = 0.024) than UCDs, whereas no significant difference was observed in MTV. The AUCs for differentiating paragangliomas and UCDs were 0.920, 0.888, 0.909, and 0.765 for SUVmax, SUVmean, SUVpeak, and TLG, respectively. The SUVmax cut-off of 7.75 yielded 82.4% sensitivity and 100% specificity for predicting paragangliomas. This study indicated that 18 F FDG PET/CT-derived multiple metabolic parameters are useful in distinguishing between paragangliomas and UCDs. SUVmax showed the best result for the differential diagnosis of these two diseases among multiple metabolic parameters.

A 27-year-old woman with known malignant pheochromocytoma was enrolled in a clinical trial to compare efficacy of 68 Ga-DOTATATE PET/ CT and 18 F-MFBG PET/CT. Images from both studies detected similar number of the metastatic lesions. In addition, both studies detected more lesions than 131 I-MIBG imaging.

Currently, glioblastoma (GBM) is the most common malignant tumor of the central nervous system in adults. Fibroblast activation protein (FAP) is a member of the dipeptidyl peptidase family, which has catalytic activity and is engaged in protein recruitment and scaffolds. Recent studies have found that FAP expression in different types of cells within the GBM microenvironment is typically upregulated compared with that in lower grade glioma and is most pronounced in the mesenchymal subtype of GBM. As a marker of cancer-associated fibroblasts (CAFs) with tumorigenic activity, FAP has been proven to promote tumor growth and invasion via hydrolysis of molecules such as brevican in the extracellular matrix and targeting of downstream pathways and substrates, such as fibroblast growth factor 21 (FGF21). In addition, based on its ability to suppress antitumor immunity in GBM and induce temozolomide resistance, FAP may be a potential target for immunotherapy and reversing temozolomide resistance; however, current studies on therapies targeting FAP are still limited. In this review, we summarized recent progress in FAP expression profiling and the understanding of the biological function of FAP in GBM and raised the possibility of FAP as an imaging biomarker and therapeutic target.

BackgroundThe purpose of this study is to compare the sensitivity of 68Ga-DOTA-JR11 and 68Ga-DOTA-TATE PET/CT for detecting the responsible tumor of tumor-induced osteomalacia (TIO) and investigate if 68Ga-DOTA-JR11 PET/CT can identify the culprit tumor of TIO in multiple suspicious lesions in 68Ga-DOTA-TATE PET/CT.MethodsA total of 19 patients with suspected TIO were prospectively recruited in this study. Each patient underwent whole-body PET/CT scan 40–60 min postinjection using 68Ga-DOTA-TATE and 68Ga-DOTA-JR11 on the same PET/CT, respectively in sequence, and on consecutive days. The diagnosis of TIO was confirmed by the combination of the postsurgical pathological results of the tumor and clinical information.ResultsAmong the 19 patients with TIO who were included in this study, culprit tumors from all patients were confirmed pathologically. 68Ga-DOTA-TATE PET/CT positively identified the causative tumor in 18/19 patients, whereas 68Ga-DOTA-JR11 PET/CT was positive in 11/19 patients (94.7% vs. 57.9%, respectively; p &lt; 0.05). 68Ga-DOTA-TATE PET/CT demonstrated more than one increased focal activity in 7 patients for a total of 16 lesions (3 lesions each in 2 patients and 2 lesions each in the rest 5 patients). However, seven of these 16 lesions showed concordant results on 68Ga-DOTA-JR11 PET/CT by demonstrating increased activity (one lesion in each of the 7 patients). The surgical specimens of the lesions in these 7 patients confirmed the phosphaturic mesenchymal tumor. A total of 11 culprit tumors were positive in both 68Ga-DOTA-TATE and 68Ga-DOTA-JR11 PET/CT. The SUVmax of 11 culprit tumors was significantly higher on 68Ga-DOTA-TATE PET/CT compared with that on 68Ga-DOTA-JR11 PET/CT (17.8 ± 12.5 vs. 6.8 ± 6.2; p &lt; 0.05).Conclusions68Ga-DOTA-TATE PET/CT is more sensitive to 68Ga-DOTA-JR11 PET/CT in the detection of the culprit tumor of TIO. However, 68Ga-DOTA-JR11 PET/CT might be helpful to identify the tumor in multiple suspicious lesions in 68Ga-DOTA-TATE PET/CT.Clinical Trial Registrationclinicaltrials.gov, identifier NCT 04689893.

Purpose Papillary renal cell carcinoma (RCC) is the second most common subtype of RCC, after clear cell RCC. This study aimed to investigate the usefulness of FDG PET/CT in primary and recurrent papillary RCC, and the role of staging FDG PET/CT in predicting survival. Methods A total of 66 patients with histopathologically confirmed papillary RCC who underwent either staging or restaging FDG PET/CT scans (30 had staging scans only, 28 had restaging scans only, 8 had both) were retrospectively included in this study. The sensitivity and specificity of restaging FDG PET/CT for detecting recurrence were assessed by histopathology and/or clinical follow-up as standard reference. Results Staging FDG PET/CT scans were performed in 38 patients, of which 31 (81.5%) showed FDG-positive primary renal lesions. The SUVmax of high-grade (WHO grade 3 and 4) papillary RCCs were significantly higher than that of low-grade (WHO grade 1 and 2) tumors (9.44 ± 6.18 vs 4.83 ± 3.19, P = 0.008). The SUVmax was not significantly different between type 1 and type 2 papillary RCCs (5.71 ± 2.88 vs. 6.99 ± 5.57, P = 0.563). Of the 38 patients, 12 developed disease progression during the follow-up period. Patients with primary tumor SUVmax> 5.85 were associated with significantly shorter progression-free survival (PFS) than those with tumor SUVmax≤5.85 (P = 0.005). Restaging FDG PET/CT scans were performed in 36 patients with suspected recurrent papillary RCCs. FDG PET/CT showed a sensitivity and specificity of 100 and 72.7% for detecting recurrent disease. Comparison of PET/CT scans with CT/MRI imaging was available in 23 patients. FDG PET/CT revealed additional findings in 11 patients, mainly including lymph node and bone metastases. FDG PET/CT findings led to change in management in 5.3% (2/38) of patients in the staging setting and 16.7 (6/36) of patients in the restaging setting. Conclusions FDG PET/CT had a sensitivity of 81.5% for detecting primary papillary RCC, and tumor SUVmax derived from staging FDG PET/CT was a predictor of PFS. In the restaging process of papillary RCC, FDG PET/CT was very effective for detecting recurrent disease.