Incidence rate and factors associated with the development of secondary cancers after radioiodine therapy in differentiated thyroid cancer: a multicenter retrospective study.

PURPOSE: The objective of this study was to estimate the incidence of secondary cancers and the factors associated with their development among patients who underwent radioiodine therapy (RIT) with differentiated thyroid cancer. METHODS: We retrospectively collected medical records for patients who underwent first RIT between January 1, 2000, and December 31, 2005, from seven tertiary hospitals in South Korea after total thyroidectomy for differentiated thyroid cancer. Cancer incidence and calculated standardized rate ratio were compared with Korean cancer incidence data. The association between the development of secondary cancers and various parameters was analyzed by Cox-proportional hazard regression. RESULTS: A total of 3106 patients were included in this study. Mean age at the time of diagnosis of thyroid cancer was 45.7 ± 13.3 years old, and 2669 (85.9%) patients were female. The follow-up period was 11.9 ± 4.6 (range, 1.2-19.6) years. A total of 183 secondary cancers, which included 162 solid and 21 hematologic cancers, occurred in 173 patients (5.6%). There was no significant difference between solid cancer incidence in our study population who underwent RIT and the overall Korean population, but the incidence of hematologic cancers and total cancer in our study was significantly higher compared with that of the Korean population. A multivariate analysis identified independent prognostic factors for the development of secondary cancer including age at 1st RIT, male, and total cumulative dose over 200 mCi. CONCLUSION: We need to assess the risk benefit for patients who receive over 200 mCi of a total cumulative dose.

Assessment of Therapeutic Response in Pyogenic Vertebral Osteomyelitis Using 18F-FDG-PET/MRI.

PURPOSE: There is still no definite method to determine therapeutic response in pyogenic vertebral osteomyelitis (PVO). We analyzed the value of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) for assessing therapeutic response in PVO. METHODS: This retrospective study included 53 patients (32 men and 21 women) with lumbar PVO. The results of clinical assessments for therapeutic response were divided into "Cured" (group C) and "Non-cured" (group NC). The differences in clinical and radiological features of PVO lesions between the two groups were analyzed using clinical data and simultaneous FDG-PET/magnetic resonance imaging (MRI) obtained at each clinical assessment. RESULTS: Clinical assessments and FDG-PET/MRIs were performed at 41.89 ± 16.08 (21-91) days of parenteral antibiotic therapy. There were 39 patients in group C and 14 in group NC. Diagnostic accuracies (DAs) of FDG uptake intensity-based interpretation and C-reactive protein (CRP) for residual PVO were as follows (p < 0.01): 84.9% of the maximum standardized uptake value of PVO lesion (PvoSUVmax), 86.8% of ΔPvoSUVmax-NmlSUVmax (SUVmax of normal vertebra), 86.8% of ΔPvoSUVmax-NmlSUVmean (SUVmean of normal vertebra), and 71.7% of CRP. DAs were better (92.5-94.3%) when applying FDG uptake intensity-based interpretation and CRP together. Under the FDG uptake distribution-based interpretation, FDG uptake was significantly limited to intervertebral structures in group C (p = 0.026). CONCLUSION: The interpretations of intensity and distribution of FDG uptake on FDG-PET are useful for detecting residual PVO in the assessment of therapeutic response of PVO. The combination of FDG-PET and CRP is expected to increase DA for detecting residual PVO.

Potential Clinical Applications of 18F-Fluorodeoxyglucose Positron Emission Tomography/Magnetic Resonance Mammography in Breast Cancer.

The whole-body positron emission tomography (PET)/magnetic resonance (MR) scan is a cutting edge technology providing comprehensive structural information from MR imaging and functional features from PET in a single session. Recent research findings and clinical experience have shown that 18F-fluorodeoxyglucose (FDG) whole-body PET/MR imaging has a diagnostic performance comparable with or superior to that of PET/CT in the field of oncology, including for breast cancer. In particular, FDG PET/MR mammography in the prone position with the breast hanging in a pendant manner can provide more comprehensive information about the metabolism, anatomy, and functional features of a breast lesion than a whole-body PET/MR scan. This article reports on current state-of-the-art PET/MR mammography in patients with breast cancer and the prospects for potential application in the future.

Quantitative assessment of simultaneous F-18 FDG PET/MRI in patients with various types of hepatic tumors: Correlation between glucose metabolism and apparent diffusion coefficient.

PURPOSE: Metabolism and water diffusion may have a relationship or an effect on each other in the same tumor. Knowledge of their relationship could expand the understanding of tumor biology and serve the field of oncologic imaging. This study aimed to evaluate the relationship between metabolism and water diffusivity in hepatic tumors using a simultaneous positron emission tomography/magnetic resonance imaging (PET/MRI) system with F-18 fluorodeoxyglucose (FDG) and to reveal the metabolic and diffusional characteristics of each type of hepatic tumor. METHODS: Forty-one patients (mean age 63 ± 13 years, 31 male) with hepatic tumors (18 hepatocellular carcinoma [HCC], six cholangiocarcinoma [CCC], 10 metastatic tumors, one neuroendocrine malignancy, and six benign lesions) underwent FDG PET/MRI before treatment. Maximum standard uptake (SUVmax) values from FDG PET and the apparent diffusion coefficient (ADC) from the diffusion-weighted images were obtained for the tumor and their relationships were examined. We also investigated the difference in SUVmax and ADC for each type of tumor. RESULTS: SUVmax showed a negative correlation with ADC (r = -0.404, p = 0.009). The median of SUVmax was 3.22 in HCC, 6.99 in CCC, 6.30 in metastatic tumors, and 1.82 in benign lesions. The median of ADC was 1.039 × 10-3 mm/s2 in HCC, 1.148 × 10-3 mm/s2 in CCC, 0.876 × 10-3 mm/s2 in metastatic tumors, and 1.323 × 10-3 mm/s2 in benign lesions. SUVmax was higher in metastatic tumors than in benign lesions (p = 0.023). Metastatic tumors had a lower ADC than CCC (p = 0.039) and benign lesions (p = 0.004). HCC had a lower ADC than benign lesions, with a suggestive trend (p = 0.06). CONCLUSION: Our results indicate that SUVmax is negatively correlated with ADC in hepatic tumors, and each group of tumors has different metabolic and water diffusivity characteristics. Evaluation of hepatic tumors by PET/MRI could be helpful in understanding tumor characteristics.

Prognostic value of preoperative 18F-FDG PET/CT in papillary thyroid cancer patients with a high metastatic lymph node ratio: a multicenter retrospective cohort study.

OBJECTIVE: Metastatic lymph node ratio (MLNR) is a known significant predictor of disease-free survival in differentiated thyroid cancer. The authors investigated the ability of preoperative fluorine-18 fluorodeoxyglucose (F-FDG) PET/CT to predict recurrence after surgery with radioactive iodine therapy considering MLNR. PATIENTS AND METHODS: A total of 274 patients who underwent preoperative PET/CT and surgery with radioactive iodine therapy were enrolled. The tumor-to-liver uptake ratio on PET/CT was calculated by dividing the maximum standardized uptake value of a primary lesion by the mean standardized uptake value of the normal liver. High F-FDG uptake was defined as tumor-to-liver uptake ratio more than the median cutoff value (2.1). MLNR was calculated by dividing the number of metastatic lymph nodes (LNs) by the number of cervical LNs removed. A high MLNR was also defined as one more than a threshold value (0.4), identified by plotting Kaplan-Meier survival curves and comparing them using the log-rank test. The prognostic significances of clinicopathologic variables were analyzed. RESULTS: Fifteen (5.5%) patients developed recurrence in the thyroid bed or in cervical LNs. Cox regression analysis showed that a high MLNR was significantly associated with a worse disease-free survival (odds ratio 6.95; 95% confidence interval: 2.36-20.47; P<0.001). A subgroup analysis of 70 patients with a high MLNR showed that only high F-FDG uptake was significantly associated with a worse disease-free survival (odds ratio 5.77; 95% confidence interval: 1.22-27.16; P=0.027). CONCLUSION: High F-FDG uptake of primary lesion on preoperative PET/CT has selective prognostic value according to the extent of metastatic LNs (MLNR>0.4).

Clinical outcomes of low-dose and high-dose postoperative radioiodine therapy in patients with intermediate-risk differentiated thyroid cancer.

PURPOSE: Recent studies have suggested that a low dose (LD) of radioiodine (RAI) is sufficient to treat differentiated thyroid cancer (DTC) even in patients with intermediate risk. However, these studies evaluated the efficacy of RAI therapy, irrespective of the results of the whole-body scan (WBS). The aim of the present study was to evaluate the response to LD and high-dose (HD) RAI therapy using two different criteria (with and without WBS results) and the reclassification system according to the revised 2015 guidelines of the American Thyroid Association in Korean intermediate-risk DTC patients. In addition, we evaluated the long-term clinical outcomes of treatment with LD and HD RAI. MATERIALS AND METHODS: In total, 204 intermediate-risk DTC patients who underwent postoperative RAI therapy at two tertiary referral hospitals from 2003 to 2004 were enrolled in the present retrospective study. One hundred and twenty-four patients were treated with 3.7 and 5.55 GBq (HD) of RAI in one center and 80 patients were treated with 1.11 GBq (LD) in the other center. The success rate of RAI therapy was assessed with or without the inclusion of WBS results in the analysis. In addition, the response to therapy during the first 2 years of follow-up after the initial RAI therapy was categorized according to the reclassification system of 2015 American Thyroid Association guidelines as excellent response, indeterminate response, biochemical incomplete response, or structural incomplete response. Recurrence was defined as a newly detected cytologically or pathologically confirmed lesion. RESULTS: There were no significant differences between the success rates of the HD and LD groups irrespective of the inclusion of WBS results in the analysis (with WBS: 54.84 vs. 45.0%, P=0.23; without WBS: 60.48 vs. 62.5%, P=0.77). The response to HD and LD RAI therapy was excellent in 54.84 and 45.0% of the patients, respectively; indeterminate in 34.68 and 30.0% of the patients, respectively; biochemical incomplete in 4.03 and 13.75% of the patients, respectively; and structural incomplete in 6.45% and in 11.25% of the patients, respectively (P=0.04). In particular, the biochemical or structural incomplete response rate was lower in patients treated with HD than in patients treated with LD (HD, 10.48%; LD, 25.0%, P=0.01). At the last follow-up (HD, median 11 years; LD, median 10 years), patients who achieved an excellent response showed no evidence of disease. After the initial RAI therapy, eight patients in the HD group and 18 patients in the LD group who achieved either indeterminate response or biochemical incomplete response received additional RAI therapy. Seven patients (indeterminate response in five patients; biochemical incomplete response in two patients) in the HD group and seven patients (indeterminate response in five patients; biochemical incomplete response in two patients) in the LD group showed recurrences. CONCLUSION: LD RAI therapy after thyroidectomy appears to be insufficient in Korean DTC patients with intermediate risk. The patients in the LD group predominantly showed biochemical or structural incomplete response to initial RAI therapy and additional RAI therapy was required.

Clinicopathological analysis and risk factors of advanced colorectal neoplasms incidentally detected by 18F-FDG PET-CT.

BACKGROUND: As the clinical use of fluorine-18-fluorodeoxyglucose PET-computed tomography (F-FDG PET-CT) has increased, the incidental finding of F-FDG uptake with subsequent diagnosis of advanced neoplasm at colorectum has increased. The aim of this study is to analyze the characteristics and risk factors of advanced colorectal neoplasm incidentally detected by F-FDG PET-CT. PATIENTS AND METHODS: Patients who underwent colonoscopy because of an incidental finding of F-FDG uptake at the colorectum from January 2006 to January 2015 at Yeungnam University Hospital were reviewed retrospectively. Advanced neoplasm was defined as adenoma of at least 10 mm, adenoma with serrated or villous component, high-grade dysplasia, and adenocarcinoma. RESULTS: Of the 19 798 candidates, 180 patients with incidental colorectal F-FDG uptake were included in this study. The indications of PET-CT were metastasis work-up, health screening, and others. The male to female ratio was 1.6 : 1 and the mean age was 62.7±11.4 years. A total of 156 lesions were detected in the colorectum and 86 (47.8%) were diagnosed as advanced neoplasms. Of the 86 patients with advanced neoplasms, 34 (39.5%) underwent an operation, 34 (39.5%) underwent endoscopic resection, and 18 (20.9%) underwent chemotherapy or conservative treatments. In univariate analysis, age of 62.5 years or older, carcinoembryonic antigen (CEA) of at least 3.4 ng/ml, maximum standardized uptake value (SUVmax) of at least 8.0, hypertension, F-FDG uptake on the rectosigmoid, and PET-CT for metastasis work-up showed a significant association with advanced neoplasm. In multivariate analysis, CEA (P=0.028), SUVmax (P<0.001) and an indication of PET-CT for metastasis work-up (P=0.008) were independent predictors of advanced neoplasm. CONCLUSION: Colonoscopy should be recommended in case of F-FDG uptake at the colorectum, particularly in patients with CEA of at least 3.4 ng/ml, SUVmax of at least 8.0, or metastasis work-up of malignancy.

Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography/Computed Tomography Findings of Post Traumatic Lymphangioma in a Young Adult Male.

The authors report the case of a 34-year-old male, who underwent a fluorine-18 fluoro deoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT) scan 7 years after trauma for the evaluation of multifocal masses in the right iliac and right inguinal areas. CT findings showed multifocal low density masses and 18F-FDG PET revealed slightly increased uptake (maximum standardized uptake value [SUVmax] 3.1). These findings did not exclude the possibility of a benign or malignant lesion. To achieve differential diagnosis, partial surgical excision was performed and a pathologic examination subsequently revealed lymphangioma. Here, the authors describe the 18F-FDG PET/CT findings of a rare case of lymphangioma resulting from trauma.

Correlation Between Apparent Diffusion Coefficients and Standardized Uptake Values in Hybrid (18)F-FDG PET/MR: Preliminary Results in Rectal Cancer.

PURPOSE: Fluorine-18-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) and diffusion-weighted magnetic resonance imaging (DWI) share the same role in clinical oncology and it is feasible to obtain the standardized uptake value (SUV) and apparent diffusion coefficient (ADC) simultaneously by emerging the hybrid positron emission tomography/magnetic resonance (PET/MR). This study investigated the correlation between the ADCs of rectal cancer lesions and their SUVs derived from hybrid PET/MR. METHODS: Nine patients with histologically proven rectal adenocarcinoma (5 men, 4 women; mean age, 70 ± 15.91 years) underwent torso (18)F-FDG PET/CT and regional hybrid (18)F-FDG PET/MR sequentially. A fixed threshold value of 40 % of maximum uptake was used to determine tumor volume of interest (VOI) on PET image; SUVmax, SUVpeak, and SUVmean were calculated automatically. A single freehand region of interest (ROI) was drawn on high b-value (b1000) DWI image and copied to corresponding ADC map to determine the ADCmean of rectal cancer lesion. Spearman's rank correlation coefficient (ρ) was calculated to determine the correlation between SUVs and ADC values. RESULTS: SUVmax, SUVpeak, and SUVmean derived by hybrid PET/MR were 12.35 ± 4.66 (mean ± standard deviation), 9.66 ± 3.15 and 7.41 ± 2.54, respectively. The ADCmean value of rectal cancer lesions was 1.02 ± 0.08 × 10(-3)mm(2)/s. ADCmean was significantly and inversely correlated with SUV values (SUVmax, ρ = -0.95, p < 0.001; SUVpeak, ρ = -0.93, p < 0.001; SUVmean, ρ = -0.91, p = 0.001). CONCLUSIONS: This preliminary hybrid PET/MR study demonstrates a significant inverse correlation exists between metabolic activity on (18)F-FDG PET and water diffusion on DWI in rectal cancer.

Multi-modality imaging for the assessment of myocardial perfusion with emphasis on stress perfusion CT and MR imaging.

High-quality and non-invasive diagnostic tools for assessing myocardial ischemia are necessary for therapeutic decisions regarding coronary artery disease. Myocardial perfusion has been studied using myocardial contrast echo perfusion, single-photon emission computed tomography, positron emission tomography, cardiovascular magnetic resonance, and, more recently, computed tomography. The addition of coronary computed tomography angiography to myocardial perfusion imaging improves the specificity and overall diagnostic accuracy of detecting the hemodynamic significance of coronary artery stenosis. This study reviews the benefits, limitations, and imaging findings of various imaging modalities for assessing myocardial perfusion, with particular emphasis on stress perfusion computed tomography and cardiovascular magnetic resonance imaging.

F-18 FDG PET/MRI findings of primary breast lymphoma in two cases: FDG PET/MRI findings of primary breast lymphoma.

We present the integrated positron emission tomography (PET)/magnetic resonance imaging (MRI) findings of diffuse large B-cell lymphoma involving the breast in two women. They were admitted with palpable breast masses. PET/MRI revealed high (18)F-fluorodeoxyglucose (FDG) uptake in multinodular enhancing masses without other FDG-avid foci. Diffusion-weighted imaging showed restricted water diffusion and dynamic contrast MRI showed rapid increase and washout kinetics. High FDG accumulation in tumor is related to washout kinetics. We present the usefulness of integrated PET/MRI for lesion characterization and total body staging in breast lymphoma.

Initial experience of integrated PET/MR mammography in patients with invasive ductal carcinoma.

The purpose of this study was to evaluate the feasibility of integrated fluorine-18-fluorodeoxyglucose positron emission tomography/magnetic resonance ((18)F-FDG PET/MR) mammography in invasive ductal carcinoma (IDC) patients. From August 2012 to March 2013, we enrolled 42 consecutive breast cancer patients who received whole- body PET/MR and subsequent PET/MR mammography by an integrated PET/MR scanner and were scheduled for surgery within 2 weeks after the of scan. On the whole body PET/MR, 2-point Dixon VIBE, coronal T1w image, axial T2w image, and post-contrast T1 sequences were acquired with simultaneous PET acquisition. For PET/MR mammography, T1w, T2w, and dynamic contrast-enhancement (DCE) sequences were acquired using a breast coil during simultaneous PET acquisition. We compared the detectability of the lesions between whole-body PET/MR and PET/MR mammography. Forty-eight IDC (1.89±1.19cm of width) were diagnosed in 42 women. Lesion conspicuity in (18)F-FDG PET was equivalent between whole-body PET/MR and PET/MR mammography; both PET/MR images showed 38 hypermetabolic masses. In the analysis of 10 IDC with <1.0cm wide lesions, only 1 IDC showed (18)F-FDG uptake, and 4 IDC were noted on whole-body PET/MR; however, all 10 IDC showed a depictable mass on PET/MR mammography. In the analysis of 38 IDC >1.0cm wide, 37 IDC showed (18)F-FDG uptake, and 38 IDC were detected on both whole-body PET/MR and PET/MR mammography. The overall sensitivity was 79.2% (38/48) on PET, 87.5% (42/48) on whole-body PET/MR, and 100% on PET/MR mammography. The SUV between whole-body PET/MR and PET/MR mammography showed strong and highly significant correlation (r=0.987, P<0.001). In conclusion, our results, although in a limited number of cases show that integrated PET/MR mammography is feasible and has the advantage of combining high-resolution breast images with metabolic images. Furthermore, PET/MR mammography could provide an accurate diagnosis in case of IDC that are less than 1cm in size.

Kikuchi-Fujimoto disease mimicking malignant lymphoma with 2-[(18)F]fluoro-2-deoxy-D-glucose PET/CT in children.

PURPOSE: Kikuchi-Fujimoto disease (KFD) is a benign disease, which is characterized by a cervical lymphadenopathy with fever, and it often mimics malignant lymphoma (ML). 2-[(18)F]fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) is a powerful imaging modality for the diagnosis, staging and monitoring of ML, with the limitations including the nonspecific FDG uptake in infectious or inflammatory processes. This study compared clinical manifestations and PET/CT findings between KFD and ML patients. METHODS: We retrospectively reviewed the medical records of 23 patients with KFD and 33 patients with ML, diagnosed histopathologically, between January 2000 and May 2013 at the Department of Pediatrics, Yeungnam University Medical Center. Among them, we analyzed the clinical manifestations, laboratory findings and characteristics, and the amount of (18)F-FDG uptake between 8 KFD and 9 ML patients who had (18)F-FDG PET/CT. RESULTS: The (18)F-FDG PET/CT maximum standardized uptake values (SUVmax) ranged from 8.3 to 22.5 (mean, 12.0) in KFDs, and from 5.8 to 34.3 (mean, 15.9) in MLs. There were no significant differences in SUVmax between KFDs and MLs. (18)F-FDG PET/CT with ML patients showed hot uptakes in the extranodal organs, such as bone marrow, small bowel, thymus, kidney, orbit and pleura. However, none of the KFD cases showed extranodal uptake (P<0.001). (18)F-FDG PET/CT findings of KFD with nodal involvement only were indistinguishable from those of ML. CONCLUSION: Patients who had extranodal involvement on PET/CT were more likely to have malignancy than KFD.

Evaluation of Dixon Sequence on Hybrid PET/MR Compared with Contrast-Enhanced PET/CT for PET-Positive Lesions.

PURPOSE: Hybrid positron emission tomography and magnetic resonance (PET/MR) imaging performs a two-point Dixon MR sequence for attenuation correction. However, MR data in hybrid PET/MR should provide anatomic and morphologic information as well as an attenuation map. We evaluated the Dixon sequence of hybrid PET/MR for anatomic correlation of PET-positive lesions compared with contrast-enhanced PET/computed tomography (CT) in patients with oncologic diseases. METHODS: Twelve patients underwent a single injection, dual imaging protocol. PET/CT was performed with an intravenous contrast agent (85 ± 13 min after (18)F-FDG injection of 403 ± 45 MBq) and then (125 ± 19 min after injection) PET/MR was performed. Attenuation correction and anatomic allocation of PET were performed using contrast-enhanced CT for PET/CT and Dixon MR sequence for hybrid PET/MR. The Dixon MR sequence and contrast-enhanced CT were compared for anatomic correlation of PET-positive lesions (scoring scale ranging from 0 to 3 for visual ratings). Additionally, standardized uptake values (SUVs) for the detected lesions were assessed for quantitative comparison. RESULTS: Both hybrid PET/MR and contrast-enhanced PET/CT identified 55 lesions with increased FDG uptake in ten patients. In total, 28 lymph nodes, 11 bone lesions, 3 dermal nodules, 3 pleural thickening lesions, 2 thyroid nodules, 1 pancreas, 1 liver, 1 ovary, 1 uterus, 1 breast, 1 soft tissue and 2 lung lesions were present. The best performance was observed for anatomic correlation of PET findings by the contrast-enhanced CT scans (contrast-enhanced CT, 2.64 ± 0.70; in-phase, 1.29 ± 1.01; opposed-phase, 1.29 ± 1.15; water-weighted, 1.71 ± 1.07; fat weighted, 0.56 ± 1.03). A significant difference was observed between the scores obtained from the contrast-enhanced CT and all four coregistered Dixon MR images. Quantitative evaluation revealed a high correlation between the SUVs measured with hybrid PET/MR (SUVmean, 2.63 ± 1.62; SUVmax, 4.30 ± 2.88) and contrast-enhanced PET/CT (SUVmean, 3.88 ± 2.30; SUVmax, 6.53 ± 4.04) in PET-positive lesions (SUVmean, ρ = 0.93; SUVmax, ρ = 0.95), although hybrid PET/MR presented a decrease of SUVs compared with contrast-enhanced PET/CT (mean reduction; SUVmean, 32.44 ± 15.64 %; SUVmax, 35.16 ± 12.59 %). CONCLUSIONS: Despite different attenuation correction approaches, the SUV of PET-positive lesions correlated well between hybrid PET/MR and contrast-enhanced PET/CT. However Dixon MR images acquired for attenuation correction were insufficient to provide anatomic information of PET images because of low spatial resolution. Thus, additional MR sequence with fast and higher resolution may be necessary for anatomic information.

Measurement of SUVs-maximum for normal region using VOI in PET/MRI and PET/CT.

The purpose of this research is to establish an overall data set associated with the VOI (Volume of Interest), which is available for simultaneous assessment of PET/MRI and PET/CT regardless of the use of contrast media. The participants as objects of this investigation are 26 healthy examinees in Korea, SUV (standardized-uptake-value)s-maximum evaluation for whole-body F-18 FDG (fluorodeoxyglucose) PET/MRI image using VOI of normal region has exhibited very significant difference to that for whole-body F-18 FDG PET/CT image (significant probability value (P) < 0.0001). However, there appeared high correlation between them in view of statistics (R-square (R) > 0.8). It is shown that one needs to decide SUVs-maximum for PET/MRI with the reduction of 25.0~26.4% from their evaluated value and needs to decide with the reduction of 28.8~29.4% in the same situation but with the use of contrast media. The use of SUVLBM-maximum (SUVLean Body Mass-maximum) is very advantageous in reading overall image of PET/CT and PET/MRI to medical doctors and researchers, if we consider its convenience and efficiency. We expect that this research enhances the level of the early stage accurate diagnosis with whole-body images of PET/MRI and PET/CT.

Very different external radiation doses in patients undergoing PET/CT or PET/MRI scans and factors affecting them.

Our aim was to determine the external radiation dose rates of patients undergoing positron emission tomography/computed tomography (PET/CT) and PET/magnetic resonance imaging (MRI) examinations, and to assess the factors affecting these doses. The external radiation dose rates (ERDR) from (18)F-FDG were measured using the Geiger-Müller tube at a distance of 10, 50, and 100cm from the patients' skin surface from various body regions. Results showed that at 10cm from the body surface for PET/CT examinations, the ERDR immediately after (18)F-FDG i.v. injection at time points 1 and 4 was 522.19±189.59µSvh(-1) and 256.36±74.94µSvh(-1) , respectively. At 10cm from the body surface for PET/MRI examinations, the ERDR at time points 1 and 4 were 258.76±92.09µSvh(-1) and 105.63±27.48µSvh(-1), respectively, always with a precipitous decrease over time. The (18)F-FDG dose was on average 1.93-fold higher and the ERDR was higher approximately 2.01 to 2.42-fold in PET/CT examinations than in PET/MRI examinations. In both PET/CT and PET/MRI patients, the ERDR was significantly higher with lower body weight, shorter stature, and fewer urinations etc. In conclusion, based on our results, the ERDR to patients from PET/CT scans at a distance of 10cm was twice as high than from the PET/MRI. Furthermore, to decrease ERDR to the patients, the dose injected should be adjusted to body weight and height. Factors like post injection fluid intake and urine bladder emptying, decrease ERDR. Other persons should keep a safe distance from the injected patient.

Prevalence of extracardiac findings in the evaluation of ischemic heart disease by multidetector computed tomography.

OBJECTIVE: Multidector computed tomography (MDCT) is now commonly used for the evaluation of coronary artery disease. Because MDCT images include many non-cardiac organs and the patient population evaluated is highly susceptible to extracardiac diseases, this study was designed to evaluate the prevalence of extracardiac findings in the MDCT evaluation of ischemic heart disease. METHODS: From March 2007 to March 2008, a total of six-hundred twenty patients, who underwent 64-slice MDCT evaluations for chest pain, or dyspnea, were enrolled in this study. Cardiac and non-cardiac findings were comprehensively evaluated by a radiologist. RESULTS: Enrolled patients included 306 men (49.4%), with a mean age of 66 years. Significant coronary artery stenosis was found in 41.6% of the patients. A total of 158 extracardiac findings were observed in 110 (17.7%) patients. Commonly involved extracardiac organs were lung (36.7%), hepatobiliary system (21.5%), thyroid (19.6%), kidney (10.8%), spine (9.7%) and breast (0.6%). Of those 110 patients, 50 (45.5%) patients underwent further diagnostic investigations. Malignant disease was detected in three (2.7%) patients (lung cancer, pancreatic cancer, and thyroid cancer). CONCLUSIONS: Extracardiac findings are frequently present and should be a concern in the MDCT evaluation of chest pain syndrome.

Diagnostic Accuracy of 64-Slice MDCT Coronary Angiography for the Assessment of Coronary Artery Disease in Korean Patients with Type 2 Diabetes.

BACKGROUND: A 64-slice multidetector computed tomography (MDCT) is well known to be a useful noninvasive form of angiography for the general population, but not for certain patients with diabetes. The aim of this study was to investigate the diagnostic accuracy and usefulness of 64-slice MDCT coronary angiography for detecting coronary artery disease in Korean patients with type 2 diabetes mellitus (T2DM). METHODS: A total of 240 patients were included, 74 of whom had type 2 diabetes (M:F=40:33; 41.8±9.5 years). We compared significant coronary stenosis (>50% luminal narrowing) in MDCT with invasive coronary angiography (ICA) by segment, artery, and patient. We also evaluated the influence of obesity and coronary calcium score on MDCT accuracy. RESULTS: Of the 4,064 coronary segments studied, 4,062 segments (T2DM=1,109) were assessed quantitatively by both MDCT and ICA, and 706 segments (T2DM=226) were detected as a significant lesion by ICA in all patients. Sensitivity, specificity, as well as positive and negative predictive values for the presence of significant stenosis in T2DM were: by segment, 89.4%, 96.4%, 85.8%, and 97.4%, respectively; by artery (n=222), 95.1%, 92.9%, 94.4%, and 93.8%, respectively; by patients (n=74), 98.4%, 100.0%, 98.4%, and 90.0%, respectively. Regardless of presence of diabetes, there was no significant difference in diagnostic accuracy. Obesity (≥25 kg/m(2)) and coronary calcium score did not also affect the diagnostic accuracy of MDCT. CONCLUSION: The 64-slice MDCT coronary angiography was found to have similar diagnostic accuracy with ICA, regardless of diabetes. These results suggest MDCT may be helpful to reduce unnecessary invasive studies for patients with diabetes.

Brain SPECT Analysis After Constraint-Induced Movement Therapy in Young Children with Hemiplegic Cerebral Palsy: Case Report.

Constraint-induced movement therapy (CIMT) was shown recently to be promising for improving upper-limb function in children with cerebral palsy (CP). This study investigated the changes in cerebral perfusion with single-photon emission computerized tomography (SPECT) after modified CIMT (child-friendly CIMT) in young hemiplegic girls. Two young children with left hemiplegic CP were studied with SPECT at rest before and after the CIMT period, and they also performed standardized upper motor function tests [Jebsen hand function test, quality of upper extremity skills test (QUEST), and dynamic electromyography (EMG)]. The cerebral perfusion SPECT revealed regional perfusion increase in the motor cortex area in the affected hemisphere, and the changes associated with functional gain. Our cases showed that intensive movement therapy appears to change local cerebral perfusion and SPECT could show these changes in children with hemiplegic CP.

Myocardial Fibrosis in Hypertrophic Cardiomyopathy Demonstrated by Integrated Cardiac F-18 FDG PET/MR.

Hypertrophic cardiomyopathy (HCM) is a common condition defined as a diffuse or segmental left ventricular (LV) hypertrophy with a nondilated and hyperdynamic chamber as well as cardiac arrhythmias. Cardiac MR (CMR) imaging is a key modality for evaluation of HCM. In addition to the assessment of LV wall thickness, LV function and aortic flow, CMR is capable of estimation of late gadolinium enhancement (LGE) in affected myocardium which has been shown to have a direct correlation with incidence and severity of arrhythmias in HCM. In patients with HCM, LGE on CMR is presumed to represent intramyocardial fibrosis. Meanwhile, F-18 FDG myocardial PET has been sporadically studied in HCM, mostly for evaluation of the metabolic status of a hypertrophic myocardial segment, especially after interventions or to demonstrate partial myocardial fibrosis. We presented here the case of a 25-year-old male patient referred for simultaneous F-18 FDG cardiac PET/MR for the evaluation of septal hypertrophy. The PET/MR revealed myocardial fibrosis in the septum associated with FDG-defect and LGE.