Ga-Prostate Specific Membrane Antigen (Ga-PSMA), a positron emission tomography (PET) tracer that was recently introduce for imaging of prostate cancer, may accumulate in other solid tumors including Hepatocellular Carcinoma (HCC). The aim of the study was to assess the potential role of Ga-PSMA PET-Computed Tomography (CT) for imaging of HCC. A prospective pilot study in seven patients with HCC with 41 liver lesions: 37 suspected malignant lesions (tumor lesions) and 4 regenerative nodules. For each liver lesion, uptake of Ga-PSMA andF-FDG uptake were measured [standard uptake value (SUV) and lesion-to-liver background ratios (TBR-SUV)], and correlated with dynamic characteristics (HU and TBR-HU) obtained on contrast enhanced CT data. Immunohistochemistry staining of PSMA in the tumor tissue was analyzed in samples obtained from 5 patients with HCC and compared to control samples from 3 patients with prostate cancer. Thirty-six of the 37 tumor lesions and none of the regenerative nodules showed increasedGa-PSMA uptake while only 10 lesions were F-FDG avid. Based on contrast enhancement, tumor lesions were categorized into 27 homogeneously enhancing lesions, nine lesions with "mosaic" enhancement composed of enhancing and non-enhancing regions in the same lesion and a single non-enhancing lesion, the latter being the only non-Ga-PSMA avid lesion. Using the Mann-Whitney test, Ga-PSMA uptake was found significantly higher in enhancing tumor areas compared to non-enhancing areas and in contrast,F-FDG uptake was higher in non-enhancing areas, P<0.001 for both. Ga-PSMA uptake (TBR SUV) was found to correlate with vascularity (TBR-HU) (Spearman r=0.866, p<0.001). Immunohistochemistry showed intense intra-tumoral microvessel staining for PSMA in HCC, in contrast with cytoplasmic and membranous staining, mainly in the luminal border, in prostate cancer samples. In two of the study patients Ga-PSMA PET-CT identified unexpected extrahepatic metastases. Four regenerative liver nodules showed no increased uptake of either of the PET tracers.Ga-PSMA PET-CT is superior to F-FDG PET-CT in imaging patients with HCC. HCC lesions are more commonly hypervascular taking upGa-PSMA in tumoral micro-vessels. Ga-PSMA PET-CT is a potential novel modality for imaging patients with HCC.

Follicular lymphoma (FL) is the 2nd most common type of lymphoma diagnosed in the Western World. Bone marrow (BM) involvement is an adverse prognostic factor in FL, routinely assessed by an arbitrary biopsy of the iliac crest. This study was aimed to investigate the role of positron emission tomography/computed tomography (PET/CT) in identifying BM involvement by FL.In this retrospective, single-center study we reviewed the records of consecutive patients with FL at diagnosis or relapse who underwent staging/restaging workup visual assessment of BM uptake was categorized as either normal, diffusely increased, or focally increased. Quantitative BM fluorine-18-fluro-deoxyglucose (FDG) uptake was measured using mean standardized uptake value (BM-SUVmean). The diagnosis of BM involvement was based on either BM histological findings or disappearance of increased uptake at end-treatment PET/CT in patients who responded to treatment.Sixty eight cases with FL were included. Sixteen (23.5%) had BM involvement, 13 (19.1%) had a biopsy proven involvement, and 3 (4.4%) had a negative BM biopsy, but increased medullary uptake that normalized post-treatment. BM FDG uptake in these patients was diffuse in 8 (50%) and focal in 8 (50%). Focal increased uptake was indicative of BM involvement; however, diffuse uptake was associated with 17 false positive cases (32.7%). Overall, visual assessment of BM involvement had a negative predictive value (NPV) of 100% and a positive predictive value (PPV) of 48.5%. On a quantitative assessment, BM-SUVmean was significantly higher in patients with BM involvement (SUVmean of 3.7 [1.7–6] vs 1.4 [0.4–2.65], P < 0.001). On receiver operator curve (ROC) analysis, BM-SUVmean > 2.7 had a PPV of 100% for BM involvement (sensitivity of 68%), while BM-SUVmean < 1.7 had an NPV of 100% (specificity of 73%).Visual assessment of PET/CT is appropriate for ruling out BM involvement by FL. Although focal increased uptake indicates marrow involvement, diffuse uptake is nonspecific. SUV measurement improves PET/CT diagnostic accuracy, identifying additional 19% of patients with BM involvement that would have been otherwise missed.

BackgroundCadmium zinc telluride (CZT) solid-state detectors have been recently introduced in the field of nuclear medicine in cardiology and breast imaging. The aim of the current study was to evaluate the performance of the novel detectors (CZT) compared to that of the routine NaI(Tl) in bone scintigraphy. A dual-headed CZT-based camera dedicated originally to breast imaging has been used, and in view of the limited size of the detectors, the hands were chosen as the organ for assessment. This is a clinical study.MethodsFifty-eight consecutive patients (total 116 hands) referred for bone scan for suspected hand pathology gave their informed consent to have two acquisitions, using the routine camera and the CZT-based camera. The latter was divided into full-dose full-acquisition time (FD CZT) and reduced-dose short-acquisition time (RD CZT) on CZT technology, so three image sets were available for analysis. Data analysis included comparing the detection of hot lesions and identification of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints.ResultsA total of 69 hot lesions were detected on the CZT image sets; of these, 61 were identified as focal sites of uptake on NaI(Tl) data. On FD CZT data, 385 joints were identified compared to 168 on NaI(Tl) data (p < 0.001). There was no statistically significant difference in delineation of joints between FD and RD CZT data as the latter identified 383 joints.ConclusionsBone scintigraphy using a CZT-based gamma camera is associated with improved lesion detection and anatomic definition. The superior physical characteristics of this technique raised a potential reduction in administered dose and/or acquisition time without compromising image quality.

Purpose: The aim of the study was to elaborate the incidence and type of skeletal involvement in a large cohort of patients with newly diagnosed prostate cancer (PCa) referred for Ga-68 PSMA-11 PET/CT staging in a single center. Methods: Study cohort included 963 consecutive patients with newly diagnosed PCa referred Ga-68 PSMA-11 PET/CT study for staging. The incidence of bone involvement, type of bone metastases, extent of disease were determined and correlated with the ISUP Grade Group (GG) criteria, and PSA levels.Results: Bone metastases were found in 188 (19.5%) of 963 patients. Osteoblastic type metastases were the most common type of bone metastases presented in 133 of the patients with malignant bone involvement (70.7%). Slightly more than half of them (54.1%) had "pure" osteoblastic lesions, while the other 45.9% had also intramedullary and/or osteolytic type lesions. Intramedullary metastases were found in 97 patients (51.6%), while 41 (21.8%) of them were "pure" intramedullary lesions. Osteolytic metastases were detected in 36 patients (19.2%), of which 8 were "pure" osteolytic lesions. Bone metastases were found in 10.7% of patients with PSA<10 ng/dL and in 27.4% of patients with PSA>10 ng/dL; in 6.1% of patients with GG≤2/3 and in 8.9% of patients with GG 4/5. In 7.6% of the patients, skeletal involvement was extensive, while 11.9% of patients had oligometastatic disease. Conclusion: Although traditionally bone metastases of PCa are considered osteoblastic; osteolytic and intramedullary metastases are common, as identi ed on PET with labeled-PSMA.

Bone metastases from prostate cancer (PCa) often show an increase in density on computed tomography (CT) after successful androgen deprivation therapy (ADT). Density may be reduced, however, as the disease progresses or, contrarily, when disease is no longer active. The current study investigated the role of 68Ga-PSMA-11 positron emission tomography/computed tomography (PET/CT) in differentiating between these two conditions. Methods: The study cohort included 15 PCa patients with sclerotic/blastic bone metastasis in whom reduction in bone density of metastasis was noted on follow-up 68Ga-PSMA-11 PET/CT after ADT. Each patient had two PET/CT scans. Prior to the first scan, six patients were castration naïve and nine patients were already treated. All patients had ADT between the two PET/CT scans. PET parameters (SUVmax and tumor-to-background ratio), and CT parameters (HUmax) were determined and compared for each lesion on both scans. Patient’s response was based on prostate-specific antigen (PSA) levels and appearance of new lesions. The Kolmogorov–Smirnov test was used to evaluate normal distribution of the continuous variables. Results: Post-ADT reduction in bone density was identified in 37 lesions. The mean HUmax was 883.9 ± 175.1 on the first scan and 395.6 ± 157.1 on the second scan (p < 0.001). Twenty-one of the 37 lesions showed no increased tracer uptake on the second PET/CT scan raising the likelihood of a response. The other 16 lesions were associated with increased uptake suggestive of an active resistant disease. Bone density was not different in lesions that no longer showed an increased uptake as compared with those that did. Seven of the study patients responded to therapy, and none of the 16 lesions found in these patients showed increased 68Ga-PSMA-11 uptake. In eight patients with progressive disease, all 12 lesions in five of them showed increased 68Ga-PSMA-11 uptake, there was mixed response in two patients (having two lesions with increased uptake and one without) and although all three lesions no longer showed an increased uptake, new lesions were detected in the eighth patient. Conclusion: A decrease in density of bone lesions may reflect clinical progression, or contrarily, a response to therapy in patients with PCa and skeletal involvement treated with ADT. Uptake of 68Ga-PSMA-11 may separate between these two vastly opposing conditions.

The role of 18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography—computed tomography (PET-CT) in assessing mucosa-associated lymphoid tissue (MALT) lymphoma is debatable. We retrospectively explored the role of [18F]FDG PET-CT in staging and predicting progression-free-survival (PFS) of patients with newly-diagnosed MALT lymphoma. Sixty-six studies were included. The maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV) and total lesion glycolysis (TLG) were documented in the “hottest” extranodal and nodal lesions. Extranodal lesions and accompanying nodal disease were detected on PET in 38/66 (57.6%) and 13/66 (19.7%) studies, respectively. Detection rate of extranodal lesions differed significantly between those located in tissues with high/heterogeneous (e.g., stomach) vs low/homogenous (e.g., subcutaneous-tissue, lung) physiologic [18F]FDG-uptake (40.4% vs. 100%, p < 0.01). Nodal lesions had significantly lower SUVmax, MTV and TLG compared with extrandodal lesions in the same patients. Detection and [18F]FDG-avidity of extranodal lesions were higher in patients with advanced, bulky disease and concomitant marrow/nodal involvement. Increased SUVmax of extranodal lesions predicted shorter PFS (HR 1.10, 95% CI 1.01–1.19, p = 0.02). Higher SUVmax and TLG showed trends towards shorter PFS in patients with localized disease. In conclusion, detection rate of extranodal MALT lymphoma lesions located in tissues with low/homogeneous physiologic [18F]FDG-uptake is excellent on [18F]FDG PET-CT. When detected, SUVmax of extranodal lesions may predict PFS.

Purpose: The recent introduction of integrated PET-MRI systems into practice seems promising in oncologic imaging. Efforts are made to specify the added-values of this modality. The current study evaluates the added-values of PET-MRI over PET-CT in detecting active malignant hepatic lesions.Methods: As part of an ongoing prospective study in our institution that assesses the added-values of PET-MRI over PET-CT, subjects undergo whole-body PET-CT and subsequent dedicated PET-MRI after single radiotracer injection. The current study included 97 consecutive paired [18F]FDG PET-CT and liver PET-MRI scans (of 61 patients) interpreted as showing active malignant hepatic involvement. Primary malignancies were of colorectal/biliary/pancreatic/breast/other origins in 19/9/9/7/17 patients. Eightysix paired scans were performed for monitoring response to therapy. When PET-MRI detected additional malignant lesions over PET-CT, lesions size, the main advantage PET-MRI offered, and the in uence on the nal report were recorded.Results: In 37/97 (38.1%) cases, a total of 78 malignant lesions were reported based on PET-MRI data only. The improved detectability on PET-MRI was evident in three groups of lesions: (1) [18F]FDG-avid lesions seen on PET of PET-MRI but not on PET of PET-CT (11 cases, 19 lesions); (2) small lesions (≤0.8cm) identi ed by MRI only (14 cases, 37 lesions); (3) lesions >0.8cm with low/no [18F]FDG-uptake categorized as viable based on MRI (12 cases, 22 lesions). These lesions caused major effect on nal reports in 11/97 (11.3%) cases, changing reported response assessment category (10/86 cases) or de ning malignant hepatic disease on staging/restaging scans (1/11 cases).Conclusion: PET-MRI offers several advantages over PET-CT in assessing the extent and response to therapy of malignant hepatic involvement. Additional malignant lesions are detected by PET-MRI due to better PET performance, greater spatial resolution provided by MRI, and improved multi-parametric viability assessment of lesions. In around one-tenth of cases, such ndings signi cantly change the nal report's conclusion.

Purpose: The aim of the study was to elaborate the incidence and type of skeletal involvement in a large cohort of patients with newly diagnosed prostate cancer (PCa) referred for Ga-68 PSMA-11 PET/CT staging in a single center.Methods: Study cohort included 963 consecutive patients with newly diagnosed PCa referred Ga-68 PSMA-11 PET/CT study for staging. The incidence of bone involvement, type of bone metastases, extent of disease were determined and correlated with the ISUP Grade Group (GG) criteria, and PSA levels.Results: Bone metastases were found in 188 (19.5%) of 963 patients. Osteoblastic type metastases were the most common type of bone metastases presented in 133 of the patients with malignant bone involvement (70.7%). Slightly more than half of them (54.1%) had "pure" osteoblastic lesions, while the other 45.9% had also intramedullary and/or osteolytic type lesions. Intramedullary metastases were found in 97 patients (51.6%), while 41 (21.8%) of them were "pure" intramedullary lesions. Osteolytic metastases were detected in 36 patients (19.2%), of which 8 were "pure" osteolytic lesions. Bone metastases were found in 10.7% of patients with PSA<10 ng/dL and in 27.4% of patients with PSA>10 ng/dL; in 6.1% of patients with GG≤2/3 and in 8.9% of patients with GG 4/5. In 7.6% of the patients, skeletal involvement was extensive, while 11.9% of patients had oligometastatic disease.Conclusion: Although traditionally bone metastases of PCa are considered osteoblastic; osteolytic and intramedullary metastases are common, as identified on PET with labeled-PSMA.