Background: Although several studies have reported an association between thyroid dysfunction and Alzheimer's disease (AD), the effect of mild thyroid dysfunction within the normal range of thyrotropin (TSH) on the development of AD remains unclear. The aim of this study was to evaluate the association between thyroid hormones and the pathology of AD in euthyroid subjects. Methods: Sixty-nine subjects with a TSH level between 0.5 and 4.5 μIU/L who underwent ¹⁸ F-florbetaben positron emission tomography were included in this prospective cross-sectional study. The levels of serum free thyroxine (fT4) and TSH were quantified using radioimmunoassay. Neuropsychological tests were performed to assess cognitive function. Differences in cerebral amyloid-β (Aβ) burden were compared between high-normal TSH (TSH ≥2.5 μIU/mL) and low-normal TSH (TSH <2.5 μIU/mL) groups. Multiple linear regression analyses, adjusted for age, sex, education level, and Neuropsychiatric Inventory scores, were performed to evaluate relationships between thyroid hormone levels and both cerebral Aβ burden and cognitive function. Results: The cerebral Aβ burden in the high-normal TSH group was significantly higher than in the low-normal TSH group (1.53 ± 0.31 vs. 1.35 ± 0.22, p = 0.009). The fT4 levels were negatively correlated with cerebral Aβ burden ( β = −0.240, p = 0.035), and TSH levels were positively correlated with cerebral Aβ burden ( β = 0.267, p = 0.020). The fT4 level was also positively associated with cognitive function, as inferred from neuropsychological test scores. Conclusions: Thyroid hormone concentrations were associated with AD pathology in euthyroid subjects. Our findings suggest that AD is likely to occur even in individuals with high-normal TSH levels.

The aim of this study was to compare the performance of a deep-learning convolutional neural network (Faster R-CNN) model to detect imaging findings suggestive of idiopathic Parkinson’s disease (PD) based on [¹⁸F]FP-CIT PET maximum intensity projection (MIP) images versus that of nuclear medicine (NM) physicians. The anteroposterior MIP images of the [¹⁸F]FP-CIT PET scan of 527 patients were classified as having PD (139 images) or non-PD (388 images) patterns according to the final diagnosis. Non-PD patterns were classified as overall-normal (ONL, 365 images) and vascular parkinsonism with definite defects or prominently decreased dopamine transporter binding (dVP, 23 images) patterns. Faster R-CNN was trained on 120 PD, 320 ONL, and 16 dVP pattern images and tested on the 19 PD, 45 ONL, and seven dVP patterns images. The performance of the Faster R-CNN and three NM physicians was assessed using receiver operating characteristics curve analysis. The difference in performance was assessed using Cochran’s Q test, and the inter-rater reliability was calculated. Faster R-CNN showed high accuracy in differentiating PD from non-PD patterns and also from dVP patterns, with results comparable to those of NM physicians. There were no significant differences in the area under the curve and performance. The inter-rater reliability among Faster R-CNN and NM physicians showed substantial to almost perfect agreement. The deep-learning model accurately differentiated PD from non-PD patterns on MIP images of [¹⁸F]FP-CIT PET, and its performance was comparable to that of NM physicians.

The distinction between primary central nervous system (CNS) lymphoma and nonmalignant lesions due to opportunistic infections, in particular cerebral toxoplasmosis, is important because of the different treatments involved. A 32-year-old patient with AIDS was hospitalized for intermittent headaches. Brain magnetic resonance imaging (MRI) showed a small well-enhanced nodular lesion in the right frontal lobe. A fluorine-18 fluorodeoxyglucose (F-18 FDG) positron emission tomography (PET)/computed tomography (CT) scan showed moderate FDG uptake in the nodular lesion of the right frontal lobe. We present a case of cerebral toxoplasmosis in a patient with acquired immunodeficiency syndrome (AIDS) and the usefulness of F-18 FDG PET/CT in the differential diagnosis of the cerebral toxoplasmosis will be discussed.

Preoperative screening for synchronous colorectal neoplasia (CRN) has been recommended in patients with gastric cancer because patients with gastric cancer are at increased risk for synchronous CRN. The aim of this study was to investigate the diagnostic accuracy of 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) for detecting synchronous advanced CRN in patients with gastric cancer. A total of 256 patients who underwent colonoscopy and 18F-FDG PET/CT for preoperative staging were enrolled in this study. The diagnosis of focal colonic 18F-FDG uptake on 18F-FDG PET/CT image was made based on histopathologic results from the colonoscopic biopsy. The 18F-FDG PET/CT result was considered as true positive for advanced CRN when focal 18F-FDG uptake matched colorectal carcinoma or adenoma with high-grade dysplasia in the same location on colonoscopy. Synchronous advanced CRN was detected in 21 of the 256 patients (4.7%). Sensitivity, specificity, and accuracy of 18F-FDG PET/CT were 76.2%, 96.2%, and 94.5%. The size of CRN with a true positive result was significantly larger than that with a false negative result. 18F-FDG PET/CT demonstrated high diagnostic accuracy for detecting synchronous advanced CRN in patients with gastric cancer. Colonoscopy is recommended as the next diagnostic step for further evaluation of a positive 18F-FDG PET/CT result in patients with gastric cancer.

This study evaluated the prognostic value of metabolic parameters based on the standardized uptake value (SUV) normalized by total body weight (bwSUV) and by lean body mass (SUL) measured on ¹⁸F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) for predicting tumor recurrence after primary living donor liver transplantation (LDLT) in patients with hepatocellular carcinoma (HCC) without transplantation locoregional therapy. This retrospective study enrolled 49 patients with HCC. The maximum tumor bwSUV (T-bwSUVmax) and SUL (T-SULmax) were measured on PET. The maximum bwSUV (L-bwSUVmax), mean bwSUV (L-bwSUVmean), maximum SUL (L-SULmax), and mean SUL (L-SULmean) were measured in the liver. All metabolic parameters were evaluated using survival analyses and compared to clinicopathological factors. Tumor recurrence occurred in 16/49 patients. Kaplan–Meier analysis revealed that all metabolic parameters were significant (p < 0.05). Univariate analysis revealed that prothrombin-induced by vitamin K absence or antagonist-II; T-stage; tumor number; tumor size; microvascular invasion; the Milan criteria, University of California, San Francisco (UCSF), and up-to-seven criteria; T-bwSUVmax/L-bwSUVmean; T-SULmax; T-SULmax/L-SULmax; and T-SULmax/L-SULmean were significant predictors. Multivariate analysis revealed that the T-SULmax/L-SULmean (hazard ratio = 115.6; p = 0.001; cut-off, 1.81) and UCSF criteria (hazard ratio = 172.1; p = 0.010) were independent predictors of tumor recurrence. SUL-based metabolic parameters, especially T-SULmax/L-SULmean, were significant, independent predictors of HCC recurrence post-LDLT.

Superior mesenteric artery (SMA) syndrome is a rare disease caused by the compression of the third portion of the duodenum between the SMA and the abdominal aorta. The prevalence is 0.005 %−0.3 % in the general population, and barium swallow for upper gastrointestinal (UGI) examination, oesophago-gastro-duodenoscopy (OGD), and imaging studies show that women are more commonly affected than men [1] [2]. In healthy individuals, the physiologic aortomesenteric angle is sustained by the left renal vein, and the uncinated process of the pancreas embedded in retroperitoneal fat and lymph tissue prevents the compression of the duodenum [2]. In SMA syndrome, acute angulation and decreased distance between the SMA and the aorta could be caused by acute weight loss, trauma, dietary disorders, surgery, and anatomical and congenital anomalies [1] [2]. It has nonspecific upper gastrointestinal (UGI) obstruction symptoms, and delayed diagnosis may lead to life-threatening conditions such as dehydration, metabolic alkalosis, peritonitis, and gastric perforation [1]. Contrast-enhanced computed tomography (CECT) findings of an acute angulation and narrow distance between the SMA and the aorta in a patient with UGI obstruction symptoms could raise clinical suspicion of SMA syndrome and contribute to making a diagnosis [3]. Meanwhile, gastric-emptying scintigraphy (GES) is a well-known imaging modality for evaluating gastroparesis and analysing gastric motility [4]. We present a case of SMA syndrome in a 55-year-old woman who presented with dyspepsia and her GES results.