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Background Quantification of volume and inflammatory activity in the fat tissue is important because these are closely related to type 2 diabetes mellitus and cardiovascular disease. Fluorine-18 fluorodeoxyglucose (F-FDG) PET/computed tomography (CT) has been utilized to measure the metabolic activity of fat tissue. In this study, we assessed the feasibility of simultaneous PET/magnetic resonance (MR) in metabolic and volumetric measurements of fat tissue and the potential advantage over PET/CT. Methods Twenty-four healthy individuals were enrolled, who underwent simultaneous F-FDG PET/MRI. Twenty-five F-FDG PET/CT scans were selected. Isocontour volumes of interest (VOIs) were used to segment and separate visceral fat (VF) and abdominal subcutaneous fat (SF) in using the MR image (T1 DIXON VIBE sequence) of PET/MR and the CT image of PET/CT. Volume, mean standardized uptake value of VF, and SF VOIs were calculated. Results Overlap between F-FDG PET and VF VOI was better in F-FDG PET/MR than PET/CT. The mean standardized uptake value of VF was associated with the degree of intestinal uptake on F-FDG PET/CT, but not on F-FDG PET/MR. Volumetric and metabolic measurements using F-FDG PET/MR showed an excellent reproducibility, with a high intraclass correlation coefficient between different observers (0.951-0.997). The measured metabolic activity was higher in VF than SF. Conclusion We established a method for the quantitative measurement of volume and metabolic status of abdominal VF and SF using simultaneous F-FDG PET/MR. F-FDG PET/MR has an advantage over F-FDG PET/CT in terms of being less confounded by intestinal uptake. This method could be used to assess the inflammatory activity of fat tissue, which is a major risk factor for type 2 diabetes mellitus and cardiovascular disease.

Objectives The prevalence and risk of malignancy in thyroid incidentalomas has been investigated in previous studies; however, these studies have not looked at the characteristics of incidental thyroid cancer (ITC) detected by fluorine-18 fluorodeoxyglucose PET. Therefore, we aimed to assess the clinicopathologic features of ITC. Methods From March 2008 to December 2011, a total of 2892 patients underwent total thyroidectomy for papillary thyroid cancer. Among them, patients belonging to the ITC group were defined as those in whom focal thyroid uptake was reported as an incidental finding on PET imaging and further evaluation revealed the presence of malignancy. In addition, two control groups with non-PET incidental thyroid cancer (NITC) were selected: NITC-A patients (n=48) who underwent a total thyroidectomy in March 2008 and NITC-B patients (n=48) who underwent a total thyroidectomy for papillary thyroid cancer and were matched for the confounding effects of age and sex. Results There were no significant differences in clinicopathologic features, except for age and tumour node metastasis (TNM) staging, between ITC and NITC-A patients. More ITC than NITC-A patients were aged 45 years or older. Although T, N, or M staging was not different between ITC and NITC-A, there were more ITC patients with stage III/IV tumours. After matching for age and sex, none of the clinicopathologic features showed significant differences between ITC and NITC-B patients. Conclusion No significant differences were observed between ITC and NITC patients except for age and TNM staging. More ITC patients had advanced TNM stage most likely due to patient age.

Methylation status of the methyl-guanine methyltransferase (MGMT) promoter is associated with a favorable response to a DNA alkylating agent in high-grade gliomas. We analyzed PET scans of patients with high-grade gliomas to determine whether the MGMT methylation status affects the tumor metabolic characteristics.Twenty-three patients with high-grade glioma, who were initially examined with 11C-methionine (MET) and 18F-fluorodeoxyglucose (FDG) PET, were retrospectively enrolled. MET and FDG PET images were coregistered to each other and quantitative uptake of MET or FDG was assessed using tumor-to-normal uptake ratio of the cortex (TNR). TNRs for MET and FDG PET were compared between the two groups classified by MGMT promoter methylation status.Maximum TNR(FDG) of the MGMT methylated group was significantly higher than that of the MGMT unmethylated group (1.80±0.90 vs. 1.29±0.19; P=0.02). The MGMT methylated group also showed a trend for increased mean TNRFDG compared with the unmethylated group (0.85±0.21 vs. 0.72±0.11; P=0.10). There was no significant difference in TNR(MET) between the groups. In subgroup analyses with WHO grade 3 and 4, a trend for higher maximum TNR(FDG) was found in the MGMT methylated group compared with the unmethylated group.The MGMT methylated group showed higher glucose metabolism compared with the unmethylated group, whereas MET uptake did not show a significant difference. This suggests that MGMT methylation in high-grade gliomas could affect the tumor glucose metabolism. Thus, MGMT methylation status can cause a discrepancy in the prognostic prediction of high-grade gliomas by FDG PET, especially in patients scheduled for DNA alkylating chemotherapeutics.

The aims of this study were to evaluate the efficacy of scintigraphy with the 99 Tc m -labelled anti-carcinoembryonic antigen (CEA) monoclonal antibody Fab' fragment (IMMU4) in the diagnosis of recurrent colorectal carcinoma and to investigate its usefulness in the intraoperative surgical management of patients undergoing re-operation because of a rising serum CEA. We evaluated 24 patients prospectively who had rising serum CEA 6-19 months after initial surgery for colorectal carcinoma. Ten patients had lesions confirmed by computed tomography, ultrasound, magnetic resonance imaging, endoscopic examination or barium enema. Fourteen patients had negative findings on one or more of the above studies, but were suspected of having occult disease from their rising serum CEA. All patients were scheduled for surgery for restaging during a 'second look' procedure. Planar and single photon emission tomography (SPET) imaging was performed in all patients. All scintigraphic findings were correlated with surgical and histopathological results. The overall sensitivity, specificity and accuracy were 81, 90 and 86% respectively when analysed by lesion, and 95, 60 and 88% respectively when analysed by patient. Ten of 14 (71%) patients with occult disease were correctly diagnosed as having recurrent disease. The SPET images were shown to have superior detectability (80%) compared with the planar images (35%). The surgeon judged the study to have had a neutral impact in 75% of the patients, but to have been helpful in 25%. We conclude that this antibody is potentially useful in detecting recurrent colorectal carcinoma in patients with rising serum CEA, especially when conventional imaging is negative or equivocal. It can also be helpful in altering planned surgery.

(18)F-FP-CIT positron emission tomography (PET) is an effective imaging for dopamine transporters. In usual clinical practice, (18)F-FP-CIT PET is analyzed visually or quantified using manual delineation of a volume of interest (VOI) for the striatum. In this study, we suggested and validated two simple quantitative methods based on automatic VOI delineation using statistical probabilistic anatomical mapping (SPAM) and isocontour margin setting.Seventy-five (18)F-FP-CIT PET images acquired in routine clinical practice were used for this study. A study-specific image template was made and the subject images were normalized to the template. Afterwards, uptakes in the striatal regions and cerebellum were quantified using probabilistic VOI based on SPAM. A quantitative parameter, QSPAM, was calculated to simulate binding potential. Additionally, the functional volume of each striatal region and its uptake were measured in automatically delineated VOI using isocontour margin setting. Uptake-volume product (QUVP) was calculated for each striatal region. QSPAM and QUVP were compared with visual grading and the influence of cerebral atrophy on the measurements was tested.Image analyses were successful in all the cases. Both the QSPAM and QUVP were significantly different according to visual grading (P 0.001). The agreements of QUVP or QSPAM with visual grading were slight to fair for the caudate nucleus (κ = 0.421 and 0.291, respectively) and good to perfect to the putamen (κ = 0.663 and 0.607, respectively). Also, QSPAM and QUVP had a significant correlation with each other (P 0.001). Cerebral atrophy made a significant difference in QSPAM and QUVP of the caudate nuclei regions with decreased (18)F-FP-CIT uptake.Simple quantitative measurements of QSPAM and QUVP showed acceptable agreement with visual grading. Although QSPAM in some group may be influenced by cerebral atrophy, these simple methods are expected to be effective in the quantitative analysis of (18)F-FP-CIT PET in usual clinical practice.