Quantitative and qualitative evaluation of sequential PET/MRI using a newly developed mobile PET system for brain imaging

[Purpose]To evaluate the clinical feasibility of a newly developed mobile PET system with MR-compatibility (flexible PET; fxPET), compared with conventional PET (cPET)/CT for brain imaging.[Methods]Twenty-one patients underwent cPET/CT with subsequent fxPET/MRI using 18F-FDG. As qualitative evaluation, we visually rated image quality of MR and PET images using a four-point scoring system. We evaluated overall image quality for MR, while we evaluated overall image quality, sharpness and lesion contrast. As quantitative evaluation, we compared registration accuracy between two modalities [(fxPET and MRI) and (cPET and CT)] measuring spatial coordinates. We also examined the accuracy of regional 18F-FDG uptake.[Results]All acquired images were of diagnostic quality and the number of detected lesions did not differ significantly between fxPET/MR and cPET/CT. Mean misregistration was significantly larger with fxPET/MRI than with cPET/CT. SUVmax and SUVmean for fxPET and cPET showed high correlations in the lesions (R = 0.84, 0.79; P < 0.001, P = 0.002, respectively). In normal structures, we also showed high correlations of SUVmax (R = 0.85, 0.87; P < 0.001, P < 0.001, respectively) and SUVmean (R = 0.83, 0.87; P < 0.001, P < 0.001, respectively) in bilateral caudate nuclei and a moderate correlation of SUVmax (R = 0.65) and SUVmean (R = 0.63) in vermis.[Conclusions]The fxPET/MRI system showed image quality within the diagnostic range, registration accuracy below 3 mm and regional 18F-FDG uptake highly correlated with that of cPET/CT

Relationship between lymph node metastasis and E-cadherin expression in submucosal invasive gastric carcinomas with gastric-phenotype

Background : Recent advances in immunohistochemical staining have led to the proposition of a classification of gastric carcinomas based on cellular phenotypes, and the degree of biological malignancy of gastric-phenotype carcinomas has attracted particular attention. Subjects and Methods : One hundred and seven submucosal (SM) invasive carcinomas encountered in our center were examined for their histological type, cellular phenotype, and E-cadherin expression status to clarify their relationships with lymph node metastasis. Results : Eleven (10.3%) of 107 SM gastric carcinomas were lymph node metastasis-positive. Gastric-phenotype carcinomas accounted for 20.6%, with a lymph node metastasis rate of 27.3% (6/22), which was significantly higher (p<0.05) than those of intestinal-phenotype carcinomas (5.9%) and mixed-phenotype carcinomas (2.9%). In terms of E-cadherin expression, only carcinomas with reduced E-cadherin expression showed lymph node metastasis at a rate significantly higher than that of carcinomas with normal E-cadherin expression (p<0.05). The lymph node metastasis rate (46.2%) of gastric-phenotype carcinomas with reduced E-cadherin expression was significantly higher than those of carcinomas of other phenotypes (p<0.05). Conclusion : Since gastric-phenotype differentiated carcinomas with reduced E-cadherin expression have the potential for becoming undifferentiated, the risk of lymph node metastasis should be considered

Clinicopathological evaluation of biological behavior of submucosal invasive gastric carcinomas : relationship among lymph node metastasis, mucin phenotype and proliferative activity

Background : Gastric carcinomas have been classified into the differentiated and undifferentiated type, on the basis of its tendency to gland formation. As a result of recent advances in mucin histochemistry, mucin phenotypes of gastric carcinomas have been investigated. However, no consensus on the evaluation of the grade of malignancy of early gastric carcinomas regarding mucin phenotype expression has developed. To address this issue, we evaluated the lymph node metastasis rate and proliferative activity of a submucosal invasive (sm) gastric carcinoma according to mucin phenotype expression. Methods : In resected surgical specimens from 108 patients with a single sm gastric carcinoma, the association between clinicopathological factors and lymph node metastasis was evaluated. In all cases, immunohistochemical staining with human gastric mucin, Muc-2, and CD10 and mucin histochemical staining by paradoxical concanavalin A staining were performed. The mucin phenotypes were classified into gastric-type (G-type), intestinal-type (I-type), mixed gastric and intestinal type (M-type), or a lack of mucin (LOM), using these as markers. To evaluate the cell proliferative activity of the gastric carcinoma, proliferating cell nuclear antigen (PCNA) staining was also performed. Results : The rate of lymph node metastasis was higher for G-type sm carcinomas. A multivariate analysis showed that the G-type and lymphatic invasion were independent factors of lymph node metastasis. However, the PCNA-labeling index (PCNA-LI) was low for G-type carcinomas irrespective of the presence or absence of lymph node metastasis. In I-type carcinomas, PCNA-LI was significantly higher in cases that were positive for lymph node metastasis than in negative cases. Conclusion : G-type and lymphatic invasion are independent risk factors for lymph node metastasis of an sm gastric carcinoma, and proliferative activity may be a significant parameter for lymph node metastasis in cases with I-type carcinomas

MR対応可搬型PET装置を用いたPET-MRI連続撮像とPET/CTとの比較

京都大学0048新制・課程博士博士(医学)甲第20981号医博第4327号新制||医||1026(附属図書館)京都大学大学院医学研究科医学専攻(主査)教授 増永 慎一郎, 教授 辻川 明孝, 教授 溝脇 尚志学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDFA

Diffusely Decreased Liver Uptake on FDG PET and Cancer-Associated Cachexia With Reduced Survival.

We investigated clinical characteristics of patients with extremely increased or decreased physiologic F-FDG uptake of the liver and their prognosis

Bone Pseudometastasis on 18F-FDG PET in Japanese Patients With Esophageal Cancer

Purpose of the Report False-positive bone lesions mimicking bone metastases (bone pseudometastasis) on 18F-FDG PET/CT have often been reported in patients with esophageal cancer. We aimed to evaluate the prevalence and features of these lesions in Japanese patients with esophageal cancer.Methods In this retrospective study, we analyzed 83 FDG PET/CT studies for initial staging of esophageal cancer, and extracted patients with 1 or more localized high uptake sites with no subsequent progression, which were therefore judged to be bone pseudometastasis. The FDG PET/CT imaging features of the bone pseudometastasis were evaluated, and other available imaging and clinical features reviewed.Results Of the 83 patients, 7 had bone pseudometastasis. All 7 were males diagnosed with squamous cell cancer, of which 5 had T1a tumors. Bone pseudometastasis showed normal or ill-defined hyperdense (nonosteolytic) sites compared with the surrounding area on the CT. Additionally, accumulation in the upper vertebral levels of each case was contiguously high compared with the lumbar spines (we named this finding “contiguous accumulation”). On MRI, these findings were visualized as low signals on T1-weighted imaging (T1WI) and T2WI images but were unclear on fat-suppressed T2WI images.Conclusions Among all PET/CT performed for staging of esophageal cancer, 8.3% demonstrated bone pseudometastasis characterized by heterogeneous distribution with severe fatty degeneration of bone marrow accompanied by contiguous accumulation. Caution is required during diagnoses of bone lesions in esophageal cancer patients in Japan to prevent inappropriate therapeutic choices

Predominance and Homogeneity Patterns of Physiological FDG Accumulation in Thoracic and Lumbar Vertebrae: Suspected Mechanism of "Bone Pseudometastasis" on FDG-PET in Japanese Patients With Esophageal Cancer

ObjectiveFalse-positive bone lesions (bone pseudometastases) have been often reported in patients with esophageal cancer (EsoC). This study aimed to evaluate the vertebral 2-deoxy-2-[18F] fluoro-D-glucose (FDG) accumulation pattern in patients with newly diagnosed esophageal cancers and other malignancies (OtherT) to elucidate the possible mechanism that causes bone pseudometastasis.MethodsFDG positron emission tomography/computed tomography performed for 90 patients with EsoC, and 112 patients with OtherT was retrospectively evaluated. The uptake pattern in the thoracic (Th) and lumbar (L) vertebrae was visually assessed regarding predominance (TL, Th ≒ L; Td, Th > L; Ld, L > Th), main intensity compared with the uptake in the blood pool (BP) (Grade 1  BP), and homogeneity (homogeneous, heterogeneous, marginal, or spotty). The patterns between EsoC and OtherT and between Th and L were compared.ResultsTL, Td, and Ld patterns were observed in 51.1%, 48.9%, and 0% in EsoC and 79.7%, 20.3%, and 0% in OtherT. Though Grade 2 was most frequently observed in both groups, the ratio of Grade 3 in Th and Grade 1 in L was significantly higher in EsoC than in OtherT. Heterogeneous and spotty patterns were more frequently observed in L and in EsoC, and these were strongly associated with Td pattern.ConclusionTd pattern was frequently seen, especially in EsoC, and was strongly associated with a heterogeneous or marginal pattern in the L. Heterogeneous marrow distribution with declined lumbar uptake is suspected as the mechanism of bone pseudometastasis

〈Case Reports〉Right atrial thrombus mimicking myxoma in antiphospholipid syndrome with secondary immune thrombocytopenic purpura

[Abstract]A 22-year-old woman was referred to our hospital due to a large right atrial mass. Echocardiography showed the mass to be pedunculated,mobile, partially calcified, internally heterogeneous,and with a rough surface. Computed tomography showed internal calcification and heterogeneity.On magnetic resonance imaging, the mass was isointense to hypointense on T1-weighted images and hypointense to hyperintense on T2-enhanced images. Simultaneously, laboratory work-up revealed antiphospholipid syndrome (APS) with secondary immune thrombocytopenic purpura (ITP). We could not definitively differentiate between myxoma or cardiac thrombus associated with APS. Preoperatively,the patient was administered γ-globulin and methylprednisolone due to ITP. Surgical resection of the mass was performed in order to avoid incarceration to the tricuspid valve or embolization. Based on gross and histologic findings, the cardiac mass was diagnosed as a thrombus. She was discharged with no postoperative bleeding. APS-associated cardiac thrombus is rare. It is difficult to distinguish APS-associated cardiac thrombus from myxoma. Moreover, ITP sometimes occurs as a complication in patients with APS. We experienced a case of right atrial thrombus mimicking myxoma in a patient with APS and secondary ITP