Incidental 18F-Florapronol Uptake in Pituitary Adenoma.

ABSTRACT: A 55-year-old man with cognitive impairment underwent 18F-florapronol brain PET/CT, a diagnostic radiotracer for the visualization of ß-amyloid plaques. Brain PET images revealed incidental 18F-florapronol uptake in the sellar region. The following contrast-enhanced MRI confirmed pituitary adenoma.

The effects of low-dose radiation therapy in patients with mild-to-moderate Alzheimer's dementia: an interim analysis of a pilot study.

PURPOSE: We aimed to determine whether low-dose radiotherapy (LDRT) is effective in patients with Alzheimer disease (AD). MATERIALS AND METHODS: We included patients according to the following criteria: probable Alzheimer's dementia according to the New Diagnostic Criteria for Alzheimer's Disease; confirmation of amyloid plaque deposits on baseline amyloid positron emission tomography (PET); a Korean Mini-Mental State Examination 2nd edition (K-MMSE-2) score of 13-26; and a Global Clinical Dementia Rating (CDR) score of 0.5-2 points. LDRT was performed six times at 0.5 Gy each. Post-treatment cognitive function tests and PET-CT examinations were performed to evaluate efficacy. The medication for AD treatment was maintained throughout the study period. RESULTS: At 6 months after LDRT, neurological improvement was seen in 20% of patients. Patient #2 showed improvement in all domains of the Seoul Neuropsychological Screening Battery II (SNSB-II). Moreover, the K-MMSE-2 and Geriatric Depression Score-Short Form scores improved from 20 to 23 and from 8 to 2, respectively. For patient #3, the CDR score (sum of box score) improved from 1 (4.0) to 1 (3.5) at 3 months follow-up. Moreover, the Z scores for language and related functions, memory, and frontal executive function improved to -2.56, -1.86, and -1.32, respectively at the 6-month follow-up. Two patients complained of mild nausea and mild hair loss during LDRT, which improved after treatment. CONCLUSION: One of the five patients with AD treated with LDRT experienced a temporary improvement in SNSB-II. LDRT is tolerable in patients with AD. We are currently under follow-up and will conduct cognitive function tests after 12 months after LDRT. A large-scale randomized controlled trial with a longer follow-up period is warranted to determine the effect of LDRT on patients with AD.

Effect of Dipeptidyl Peptidase-4 Inhibitors on Bone Health in Patients with Type 2 Diabetes Mellitus.

Patients with type 2 diabetes (T2DM) have a higher risk of bone fracture even when bone mineral density (BMD) values are normal. The trabecular bone score (TBS) was recently developed and used for evaluating bone strength in various diseases. We investigated the effect of DPP-4 inhibitors on bone health using TBS in patients with T2DM. This was a single-center, retrospective case-control study of 200 patients with T2DM. Patients were divided into two groups according to whether they were administered a DPP-4 inhibitor (DPP-4 inhibitor group vs. control group). Parameters related to bone health, including BMD, TBS, and serum markers of calcium homeostasis, were assessed at baseline and after one year of treatment. We found TBS values increased in the DPP-4 group and decreased in the control, indicating a significant difference in delta change between them. The BMD increased in both groups, with no significant differences in delta change between the two groups observed. Serum calcium and 25-hydroxy vitamin D3 increased only in the DPP-4 inhibitor group, while other glycemic parameters did not show significant differences between the two groups. Treatment with DPP-4 inhibitors was associated with favorable effects on bone health evaluated by TBS in patients with T2DM.

A Phase 0 Microdosing PET/CT Study Using O-[18F]Fluoromethyl-d-Tyrosine in Normal Human Brain and Brain Tumor.

PURPOSE: The aim of the present study was to obtain information about distribution, radiation dosimetry, toxicity, and pharmacokinetics of O-[18F]fluoromethyl-d-tyrosine (d-18F-FMT), an amino acid PET tracer, in patients with brain tumors. PATIENTS AND METHODS: A total of 6 healthy controls (age = 19-25 years, 3 males and 3 females) with brain PET images and radiation dosimetry and 12 patients (median age = 60 years, 6 males and 6 females) with primary (n = 5) or metastatic brain tumor (n = 7) were enrolled. We acquired 60-minute dynamic brain PET images after injecting 370 MBq of d-18F-FMT. Time-activity curves of d-18F-FMT uptake in normal brain versus brain tumors and tumor-to-background ratio were analyzed for each PET data set. RESULTS: Normal cerebral uptake of d-18F-FMT decreased from 0 to 5 minutes after injection, but gradually increased from 10 to 60 minutes. Tumoral uptake of d-18F-FMT reached a peak before 30 minutes. Tumor-to-background ratio peaked at less than 15 minutes for 8 patients and more than 15 minutes for 4 patients. The mean effective dose was calculated to be 13.2 µSv/MBq. CONCLUSIONS: Using d-18F-FMT as a PET radiotracer is safe. It can distinguish brain tumor from surrounding normal brain tissues with a high contrast. Early-time PET images of brain tumors should be acquired because the tumor-to-background ratio tended to reach a peak within 15 minutes after injection.

Prediction of tumor differentiation using sequential PET/CT and MRI in patients with breast cancer.

OBJECTIVE: The aim of this study is to assess tumor differentiation using parameters from sequential positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) in patients with breast cancer. METHODS: This retrospective study included 78 patients with breast cancer. All patients underwent sequential PET/CT and MRI. For fluorodeoxyglucose (FDG)-PET image analysis, the maximum standardized uptake value (SUVmax) of FDG was assessed at both 1 and 2 h and metabolic tumor volume (MTV) and total lesion glycolysis (TLG). The kinetic analysis of dynamic contrast-enhanced MRI parameters was performed using dynamic enhancement curves. We assessed diffusion-weighted imaging (DWI)-MRI parameters regarding apparent diffusion coefficient (ADC) values. Histologic grades 1 and 2 were classified as low-grade, and grade 3 as high-grade tumor. RESULTS: Forty-five lesions of 78 patients were classified as histologic grade 3, while 26 and 7 lesions were grade 2 and grade 1, respectively. Patients with high-grade tumors showed significantly lower ADC-mean values than patients with low-grade tumors (0.99 ± 0.19 vs.1.12 ± 0.32, p = 0.007). With respect to SUVmax1, MTV2.5, and TLG2.5, patients with high-grade tumors showed higher values than patients with low-grade tumors: SUVmax1 (7.92 ± 4.5 vs.6.19 ± 3.05, p = 0.099), MTV2.5 (7.90 ± 9.32 vs.4.38 ± 5.10, p = 0.095), and TLG2.5 (40.83 ± 59.17 vs.19.66 ± 26.08, p = 0.082). However, other parameters did not reveal significant differences between low-grade and high-grade malignancies. In receiver-operating characteristic (ROC) curve analysis, ADC-mean values showed the highest area under the curve of 0.681 (95%CI 0.566-0.782) for assessing high-grade malignancy. CONCLUSIONS: Lower ADC-mean values may predict the poor differentiation of breast cancer among diverse PET-MRI functional parameters.

The Predictive Values of Lesion Size, F-18 FDG Avidity and I-131 Avidity for the Clinical Outcome of I-131 Treatment in Patients with Metastatic Differentiated Thyroid Carcinoma Only in the Lung.

PURPOSE: We aimed to evaluate the prognostic values of radiography, F-18 FDG PET, and I-131 whole body scans in patients with lung-only metastasis from differentiated thyroid carcinoma (DTC). METHODS: Between 1998 and 2013, we included 31 patients (F: 26, M: 5) with lung-only metastasis from DTC who had been treated with I-131 and underwent PET. Lung metastasis was categorized according to the size (macronodular ≥1.0 cm vs. micronodular <1.0 cm), FDG avidity (avid vs. non-avid), and I-131 avidity (avid vs. non-avid). Progression-free survival (PFS) was evaluated for each patient. RESULTS: Among 31 patients, seven (23%) had macronodular lung metastasis, 26 (84%) had FDG avid lung metastasis, and 16 (52%) had I-131 avid lung metastasis. During the median follow-up period of 9.4 y, median PFS was 6.1 y. Based on Kaplan-Meier analysis, macronodular lung metastasis (p = 0.017) and I-131 non-avid lung metastasis (p = 0.059) were significantly associated with worse outcomes, but FDG avid lung metastasis was not (p = 0.135). Patients with FDG non-avid lung metastasis did not experience disease progression during follow-up, while 11 of 26 patients (42%) experienced disease progression. Based on univariate analysis, the hazard ratio for a poor prognosis was 3.78 (p = 0.029) for macronodular lung metastasis and 3.29 (p = 0.079) for I-131 non-avid lung metastasis. CONCLUSIONS: Macronodular and I-131 non-avid lung metastasis were associated with a poor prognosis in lung-only metastasis from DTC. Although FDG avid lung metastasis may be associated with a poor prognosis, a larger-scale study is needed.

Head-to-head comparison of 18 F-FP-CIT and 123 I-FP-CIT for dopamine transporter imaging in patients with Parkinson's disease: A preliminary study.

123 I-FP-CIT and 18 F-FP-CIT are radiotracers which are widely used to diagnose Parkinson's disease (PD). However, to our knowledge, no studies to date have made head-to-head comparisons between 123 I-FP-CIT and 18 F-FP-CIT. Therefore, in this study, 123 I-FP-CIT SPECT/CT was compared with 18 F-FP-CIT PET/CT in the same cohort of subjects. Patients with PD and essential tremor (ET) underwent 123 I-FP-CIT SPECT/CT and 18 F-FP-CIT PET/CT. Visual and semiquantitative analyses were conducted. The specific binding ratio (SBR) and putamen to caudate ratio (PCR) were compared between subjects who underwent 123 I-FP-CIT SPECT/CT and 18 F-FP-CIT PET/CT. Visual analysis showed that the striatal uptake of both radiotracers was decreased in the PD group, whereas striatal uptake was intact in the ET group. The SBR between 123 I-FP-CIT SPECT/CT and 18 F-FP-CIT PET/CT showed a positive correlation (r = .78, p < .01). However, the mean SBRs on 18 F-FP-CIT PET/CT were higher than those on 123 I-FP-CIT SPECT/CT (2.19 ± .87 and 1.22 ± .49, respectively; p < .01). The PCRs in these two modalities were correlated with each other (r = .71, p < .01). The mean PCRs on 18 F-FP-CIT PET/CT were not significantly higher than those on 123 I-FP-CIT SPECT/CT (1.31 ± .19 and 0.98 ± .06, respectively; p = .06). These preliminary results indicate that the uptake of both 123 I-FP-CIT and 18 F-FP-CIT was decreased in the PD group when compared with the ET controls. Visual analyses using both methods did not affect the diagnostic accuracy in this study. However, semiquantitative analysis indicated a better contrast of 18 F-FP-CIT PET/CT relative to 123 I-FP-CIT SPECT/CT.

The Relationship Between Estrogen Receptor, Progesterone Receptor and Human Epidermal Growth Factor Receptor 2 Expression of Breast Cancer and the Retention Index in Dual Phase (18)F-FDG PET/CT.

PURPOSE: This study investigates the correlation of retention index (RI) using the dual phase FDG PET/CT scan with the breast cancer biomarkers. METHODS: A total of 55 patients with breast cancer underwent dual phase FDG PET/CT scans (60 and 120 min after FDG injection) before treatment. SUVmax and SUVmean of the primary breast tumors were measured, then the percent change of SUVmax and SUVmean between the two scans were calculated, and denoted as RImax and RImean, respectively. After the surgical resection of the breast tumor, the status of biomarkers (ER, PR, and HER-2) was evaluated in the postsurgical specimen. RESULTS: RImean was significantly higher in ER (-) (median, 16.2; IQR, 10.8-21.0) or HER-2 (+) (median, 16.1; IQR, 10.7-21.6) tumors than in ER (+) tumors (median, 9.9; IQR, 5.5-15.3) or HER-2 (-) tumors (median, 10.5; IQR, 5.5-16.1). However, there were no significant differences of SUVmax or RImax according to the ER or HER-2 status. There were no significant differences of any PET parameters between PR (+) and PR (-) tumors. Based off ROC curve analyses, RImean predicted the ER (+) tumors (AUC, 0.699; p = 0.006), and HER-2 (+) tumors (AUC, 0.674; p = 0.022), but not the PR (+) tumors. However, neither SUVmax nor RImax predicted ER (+), PR (+), or HER-2 (+) tumors. CONCLUSIONS: Retention index of SUVmean can reflect the ER and HER-2 status of breast cancers. Higher retention index of SUVmean might associate with lower ER expression and higher HER-2 expression.

Visceral adipose tissue is prognostic for survival of diffuse large B cell lymphoma treated with frontline R-CHOP.

The potential role of visceral adipose tissue (VAT) as a prognostic factor in patients with diffuse large B cell lymphoma (DLBCL) treated with frontline rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone (R-CHOP) immunochemotherapy was explored. Total adipose tissue and VAT were measured by analyzing positron emission tomography (PET)/computed tomography (CT) images obtained during the initial staging of patients with DLBCL. The VAT ratio was calculated as follows: VAT ratio = VAT area/total adipose tissue area. Body mass index (BMI), sex, and International Prognostic Index (IPI) were also incorporated as co-variates in the final model of multivariate Cox regression analysis for survival. A total of 156 patients with DLBCL, who were treated with frontline R-CHOP, were enrolled in our study. The median patient age was 61 years, and 81 patients were male (51.9 %). The median cycle of R-CHOP was six. The IPI risk group was a strong prognostic factor for progression-free survival (PFS) and overall survival (OS) (p < 0.001). Obese BMIs were an independent prognostic factor for PFS, but not for OS in multivariate analyses, compared to patients with normal BMIs (HR = 0.43, 95 % CI = 0.19-0.98, and p = 0.046 for PFS). A high VAT ratio (third tertile) was an independent adverse prognostic factor for PFS and OS in multivariate analyses (HR = 2.87 and 2.66, 95 % CI = 1.30-6.32 and 1.30-5.44, and p = 0.009 and 0.007 for PFS and OS, respectively). VAT ratio was an independent prognostic factor for patients with DLBCL treated with first-line R-CHOP; thus, additional large prospective studies are warranted.

Perirenal (18)F-FDG Uptake in a Patient with a Pheochromocytoma.

Increased (18)F-fluorodeoxyglucose (FDG) uptake of brown fat on (18)F-FDG positron emission tomography (PET) originating from physiological activation is a common incidental finding and is usually located in the neck, shoulder, and supraclavicular areas. We present a case of an incidental pheochromocytoma showing diffusely increased (18)F-FDG uptake in bilateral perirenal fat tissue as well as supraclavicular and paravertebral fat tissue on (18)F-FDG PET/CT. The patient had no clinical symptoms except hypertension, and a pheochromocytoma was confirmed in a postsurgical specimen. A pheochromocytoma should be considered a cause in cases of increased (18)F-FDG uptake of perirenal brown fat.

Tumor SUVmax Normalized to Liver Uptake on (18)F-FDG PET/CT Predicts the Pathologic Complete Response After Neoadjuvant Chemoradiotherapy in Locally Advanced Rectal Cancer.

PURPOSE: This study investigates the feasibility of using (18)F-fluorodeoxyglucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) to predict the pCR (pathologic complete response) rate after neoadjuvant chemoradiotherapy (NCRT) in patients with locally advanced rectal cancer. METHODS: A total of 88 patients with locally advanced rectal cancer were retrospectively analyzed. All patients were treated with NCRT, followed by radical surgery, and (18)F-FDG PET/CT was performed before and after NCRT. For a semiquantitative assessment, a volume of interest was drawn, including the whole tumor region, and the maximum SUV (SUVmax), SUVmax normalized to liver uptake (SLR), SUVmax normalized to blood pool uptake (SBR), the metabolic tumor volume at SUV 2.0 (MTV[2.0]), SUV 2.5 (MTV[2.5]), and SUV 3.0 (MTV[3.0]) were measured. In addition, their percentage changes after NCRT were assessed. The pCR was verified through a histologic examination of postsurgical specimens. A receiver operating characteristic curve analysis was conducted to predict the pCR by using these PET parameters. RESULTS: The pCR was predicted in 17 patients (19 %). The values of the area under the curve (AUC) for predicting the pCR were 0.774 for SUVmax after NCRT, 0.826 for SLR after NCRT, 0.815 for SBR after NCRT, 0.724 for MTV(2.5) after NCRT, 0.729 for the percentage change in SUVmax, 0.700 for the percentage change in SLR, and 0.749 for the percentage change in MTV (2.5). Among these PET parameters, SLR after NCRT showed the highest AUC value. The optimal criterion, sensitivity, specificity, and accuracy of SLR after NCRT for predicting the pCR were ≤1.41, 88 %, 65 %, and 68 %, respectively. CONCLUSIONS: F-FDG PET was found to be useful for predicting the pCR after NCRT in patients with locally advanced rectal cancer. Among various PET parameters, SUVmax normalized to liver uptake after NCRT was the best predictor of the pCR.