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Background: Total metabolic tumor volume (TMTV) in 18F-fluorodeoxyglucose (FDG) positron emission tomography (PET) predicts patient outcome in follicular lymphoma (FL); however, it requires laborious segmentation of all lesions. We investigated the prognostic value of the metabolic bulk volume (MBV) obtained from the single largest lesion. Methods: Pretreatment FDG PET/computed tomography (CT) scans of 201 patients were analyzed for TMTV and MBV using a 41% maximum standardized uptake value (SUVmax) threshold. Results: During a median follow-up of 3.2 years, 54 events, including 14 deaths, occurred. Optimal cut-offs were 121.1 cm3 for TMTV and 24.8 cm3 for MBV. Univariable predictors of progression-free survival (PFS) included a high Follicular Lymphoma International Prognostic Index 2 (FLIPI2) score, TMTV, and MBV. In the multivariable analysis, high TMTV and MBV were independent predictors of worse PFS (P =0.015 and 0.033). Furthermore, in a sub-group with FLIP2 scores of 0-2 (n = 132), high MBV could identify patients with worse PFS (P = 0.007). Conclusion: Readily measurable MBV is useful for stratifying risk in FL patients. [ABSTRACT FROM AUTHOR]

Background: Although the standardized uptake value ratio (SUVR) method is objective and simple, cut-off optimization using global SUVR values may not reflect focal increased uptake in the cerebrum. The present study investigated clinical and neuroimaging characteristics according to focally increased β-amyloid (Aβ) uptake and global Aβ status. Methods: We recruited 968 participants with cognitive continuum. All participants underwent neuropsychological tests and 498 18F-florbetaben (FBB) amyloid positron emission tomography (PET) and 470 18F-flutemetamol (FMM) PET. Each PET scan was assessed in 10 regions (left and right frontal, lateral temporal, parietal, cingulate, and striatum) with focal-quantitative SUVR-based cutoff values for each region by using an iterative outlier approach. Results: A total of 62 (6.4%) subjects showed increased focal Aβ uptake with subthreshold global Aβ status [global (-) and focal (+) Aβ group, G(-)F(+) group]. The G(-)F(+) group showed worse performance in memory impairment (p < 0.001), global cognition (p = 0.009), greater hippocampal atrophy (p = 0.045), compared to those in the G(-)F(-). Participants with widespread Aβ involvement in the whole region [G(+)] showed worse neuropsychological (p < 0.001) and neuroimaging features (p < 0.001) than those with focal Aβ involvement G(-)F(+). Conclusion: Our findings suggest that individuals show distinctive clinical outcomes according to focally increased Aβ uptake and global Aβ status. Thus, researchers and clinicians should pay more attention to focal increased Aβ uptake in addition to global Aβ status. [ABSTRACT FROM AUTHOR]

Objective: Uterine leiomyosarcoma (LMS) is a rare and aggressive disease with poor outcome. Due to its rarity and conflict of data, investigation on finding prognostic factor is challenging. The aim of the study was to investigate the prognostic significance of preoperative 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) in uterine LMS. Methods: This was a retrospective observational cohort study in 3 tertiary referral hospitals. We retrospectively evaluated data from patients with pathologically proven uterine LMS who underwent preoperative 18F-FDG PET/CT scans at 3 institutions. The prognostic implication of PET/CT parameters and other clinico-pathological parameters on disease-free survival (DFS) and overall survival (OS) was evaluated. Results: Clinico-patholgical data were reviewed for 19 eligible patients. In the group overall, median DFS and OS were 12 and 20 months, respectively. As for the recurrence, large tumor size, and high tumor maximum standardized uptake value (SUVmax) were demonstrated as risk factors of recurrence. As for the OS, high tumor SUVmax was demonstrated as the unique risk factor. There were significant differences in tumor size, mitotic count, SUVmax, and DFS between patients with and without recurrence. Also, there were significant differences in tumor size, SUVmax, DFS, and OS between 2 subgroups stratified by cut-off SUVmax. Conclusion: SUVmax at preoperative 18F-FDG PET/CT was associated with worse outcome in patients with uterine LMS. In the preoperative setting, SUVmax can be a valuable non-invasive prognostic marker. Additionally, SUVmax can help identify highly aggressive uterine LMS and may help in adjusting standard treatment toward an individualized, risk-adapted treatment. [ABSTRACT FROM AUTHOR]

Cerebrovascular deposition of amyloid-β, known as cerebral amyloid angiopathy (CAA), is associated with MRI findings of lobar hemorrhage, cerebral microbleeds, and cortical superficial siderosis. Although pathological studies suggest that tau may co-localize with vascular amyloid, this has not yet been investigated in CAA in vivo. Three patients with probable CAA underwent 11C-Pittsburgh Compound B (PiB) PET or 18F-florbetaben PET to evaluate amyloid burden, and 18F-AV-1451 PET to evaluate paired helical filament tau burden. Regions that had cerebral microbleeds or cortical superficial siderosis largely overlapped with those showing increased 18F-AV-1451. Our preliminary study raised the possibility that lobar cerebral microbleeds, and cortical superficial siderosis, which are characteristic markers of vascular amyloid, may be associated with local production of paired helical filament tau. [ABSTRACT FROM AUTHOR]

Objective: This study investigated the value of fluorine-18 fludeoxyglucose (18F-FDG) heterogeneity as an indicator of metastatic lymph nodes (LNs) in patients with nasopharyngeal carcinoma (NPC). We further assessed whether addition of this parameter improves diagnostic performance beyond that provided by maximum standardized uptake value (SUVmax). Methods: We analyzed 74 LNs that were suspicious for metastasis. These LNs were measured for coefficient of variation (CV) of 18F-FDG uptake, which was used as a parameter for 18F-FDG heterogeneity. Results: Multivariate logistic regression analyses revealed that a high CV (hazard ratio, 20.97; 95% confidence interval, 2.26–194.62; p = 0.007) was an independent predictor of metastatic LNs. However, receiver-operating characteristic curve analysis (p = 0.278) and net reclassification (p = 0.539) were unable to show improved diagnostic performance by addition of CV to SUVmax. Conclusion: High CV of 18F-FDG uptake is an independent risk factor for metastatic LNs in patients with NPC displaying suspicious LNs following treatment. Advances in knowledge: Heterogeneity of 18F-FDG uptake has a potential as a biomarker of metastatic LNs. [ABSTRACT FROM AUTHOR]

Purpose Parameters of positron emission tomography-computed tomography (PET-CT) were compared with the results of histopathologic examination in order to determine which can provide an objective indication of response after neoadjuvant chemoradiation for treatment of thoracic esophageal squamous cell carcinoma (SCC). Materials and Methods Between August 2003 and January 2010, data on 25 patients who underwent neoadjuvant chemoradiation and subsequent resection for treatment of esophageal SCC were retrospectively reviewed. Changes in maximum standardized uptake value (ΔSUVmax), metabolic tumor volume (ΔMTV), and total lesion glycolysis (ΔTLG) were analyzed by comparison with the histopathologic findings. Results Pathologic complete remission (CR) for the main tumor was achieved in 11 patients. Postradiation esophagitis was observed in 10 patients. ΔSUVmax of the main tumor was significantly greater in the CR group than in the partial response (PR) group (p=0.039), while ΔMTV and ΔTLG of the main tumor were not (p=0.141 and p=0.349, respectively). The cut-off ΔSUVmax value for CR was estimated as 72.1%, indicating significantly better accuracy than visual interpretation (p=0.045). Of the 48 involved lymph nodes, ΔSUVmax and ΔMTV of lymph nodes were significantly greater in the CR group than in the PR group (p=0.045 and p=0.014, respectively), while ΔTLG was not (p=0.063). The cut-off value of ΔSUVmax for prediction of CR in lymph nodes was calculated as 50.67%. Conclusion PET-CT could be used for prediction of response to neoadjuvant treatment in thoracic esophageal SCC. ΔSUVmax may be a more significant predictor for CR after neoadjuvant chemoradiation than ΔTLG and ΔMTV. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to assess the clinical outcome of redifferentiation therapy using retinoic acid (RA) in combination with I therapy, and to identify biological parameters that predict therapeutic response in Korean patients with radioiodine-refractory papillary thyroid carcinoma (PTC). Materials and methods: A total of 47 patients (13 men, 34 women; age 54.2 ± 13.6 years) with radioiodine-refractory PTC underwent therapy consisting of consecutive treatment with I and RA. Each I/RA treatment cycle involved the administration of oral isotretinoin for 6 weeks at 1-1.5 mg/kg daily followed by a single oral dose of I (range 5.5-16.7 GBq). Therapeutic responses were determined using serum thyroglobulin (Tg) levels and the change in tumour size 6 months after completing the I/RA therapy. Biological parameters and pathological parameters before and after combined therapy were compared. Results: After completing I/RA therapy, 1 patient showed a complete response, 9 partial response, 9 stable disease, and 28 progressive disease, representing an overall response rate of 21.3%. Univariate analysis revealed that an age of <45 years and a persistently high serum Tg level were related to a good response. No clinical response was achieved when metastases showing no iodine uptake were present. Multivariate regression analysis showed that an age of <45 years was significantly associated with a good response. Of the 24 patients with well-differentiated carcinoma, 5 (20.8%) responded to I/RA therapy, whereas all 6 patients with poorly differentiated carcinoma failed to respond. Conclusion: I/RA therapy was found to elicit a response rate of 21.3% among patients with radioiodine-refractory PTC, and an age of <45 years was found to be significantly associated with a good response. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this study was to determine the most useful parameter of dual-time-point 2-deoxy-2-[¹⁸F]fluoro-D: -glucose positron emission tomography/computed tomography (PET/CT) for detection of hepatic metastases in patients with colorectal cancer.Procedures: Thirty-nine patients had undergone a dual-time-point PET/CT scan and a subsequent histopathological confirmation for a workup of hepatic metastases. Detection rates were compared for visual analysis score, standardized uptake value (SUV), tumor-to-liver uptake ratio (TLR), and percent changes of the SUV and TLR.Results: Of 91 liver lesions, 86 lesions were confirmed as metastases. The SUV and TLR of metastatic lesions on the delayed images were higher than those on the first scan (p < 0.001). The signal-to-noise ratio of the delayed PET scan was higher than that of the first scan (p < 0.0001). The TLR and SUV of the delayed scan showed the highest detection rates of 92% and 88%, whereas percent changes of SUV and TLR showed the lowest detection rates (51%, 67%). Visual analysis detected 87% on the delayed scan and 77% on the first scan.Conclusions: A delayed scan is more favorable for the detection of hepatic metastases of colorectal cancer, and the TLR on the delayed scan was the most useful parameter. [ABSTRACT FROM AUTHOR]