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Background: Due to their location and growth patterns, retroperitoneal tumors often involve the surrounding blood vessels. Clinical decisions on a proper treatment depend on the information on this condition. Evaluation of blood vessels using non‐contrast‐enhanced vessel wall MRI may provide noninvasive assessment of the extent of tumor invasion to assist clinical decision‐making. Purpose: To investigate the performance and potential of non‐contrast‐enhanced vessel wall MRI in evaluating the degree of vessel wall invasion of retroperitoneal tumors. Study Type: Prospective. Population: Thirty‐seven participants (mean age: 60.59 ± 11.77 years, 59% male) with retroperitoneal tumors close to vessels based on their diagnostic computer tomography. Field Strength/Sequences: 3 T; vessel wall MRI sequences: two‐dimensional T2‐weighted MultiVane XD turbo spin‐echo (2D‐T2‐MVXD‐TSE) and three‐dimensional T1‐weighted motion sensitized driven equilibrium fat suppression turbo spin‐echo (3D‐T1‐MSDE‐TSE) sequences; conventional MRI sequences: T2‐weighted fat suppression turbo spin‐echo (T2‐FS‐TSE), T2‐weighted turbo spin‐echo (T2‐TSE), modified Dixon T1‐weighted fast field echo (T1‐mDixon‐FFE), and diffusion‐weighted echo planar imaging (DWI‐EPI) sequences. Assessment: All patients underwent preoperative imaging using both non‐contrast conventional and vessel wall MRI sequences. Images obtained from conventional and vessel wall MRI sequences were evaluated independently by three junior radiologists (3 and 2 years of experience in reading MRI) and reviewed by one senior radiologist (25 years of experience in reading MRI) to assess the degree of vessel wall invasion. MRI were validated results from the clinical standard diagnosis based on surgical confirmation or histopathological reports. Interobserver agreement was determined based on the reports from three readers with similar years of experiences. Intraobserver variability was assessed based on categorizing and recategorizing the vessels of 37 patients 1 month apart. Statistical Tests: Intra‐class correlation efficient (ICC), Chi‐square test, McNemar test, area under the receiver‐operating characteristic curve (AUC), Delong test, P < 0.05 was considered significant. Results: The accuracy of vessel wall MRI (91.96%, 95% CI: 85.43–95.71; 103 of 112) in detecting the degree of vessel wall invasion was significantly higher than that of conventional MRI (75%, 95% CI: 66.24–82.10; 84 of 112). The interobserver variability or reproducibility in categorization of the degree of vascular wall invasion was good in evaluating images from conventional and vessel wall MRI sequences (ICC = 0.821, 95% CI: 0.765–0.867 and ICC = 0.881, 95% CI: 0.842–0.913, respectively). Data Conclusion: Diagnosis of vessel wall invasion of retroperitoneal tumors and assessment of its severity can be improved by using non‐contrast‐enhanced vessel wall MRI. Evidence Level: 1 Technical Efficacy: Stage 3 [ABSTRACT FROM AUTHOR]

Objectives: This study aims to investigate and develop imaging biomarkers for the diagnosis of cancer-associated cachexia based on the organ and tissue-specific abnormal metabolisms measured by fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT. Methods: FDG PET/CT data from 390 cancer patients were analyzed retrospectively. Patients were divided into a development cohort and a validation cohort. Cachexia was defined as weight loss > 5% in 6 months or BMI < 20 and weight loss > 2%. According to the above definitions, patients were divided into cachexia and non-cachexia groups. Results of the clinical laboratory tests for metabolic levels and organ and tissue-specific FDG uptake obtained from the cachexia and non-cachexia groups were compared statistically. Logistic regression analysis was performed to identify independent variables associated with cachexia in the development cohort for generating the regression model. The performance of the model was tested using the data from a validation cohort and evaluated by area under the receiver operating characteristic curve (AUC). Results: Based on the data from the development cohort of 286 patients and a validation cohort of 104 patients, it is found that age, white blood cell count, peak standardized uptake value (SUV) of the liver, and minimum SUV of lean body mass of visceral fat and subcutaneous fat were independently associated with cachexia. The model incorporating these variables reached an AUC of 0.777 (95% confidence interval (CI): 0.721, 0.833) in the development cohort and an AUC of 0.729 (95% CI: 0.629, 0.829) in the validation cohort. Conclusion: Organ and tissue-specific abnormal glucose metabolism as measured by PET/CT can be used as a biomarker for cancer-associated cachexia. Key Points: • Patients with cancer-associated cachexia have reduced FDG uptake in the liver and increased FDG uptake in visceral fat and subcutaneous fat. • FDG uptake of the liver, visceral fat, and subcutaneous fat can be independent risk factors for identifying cancer-associated cachexia. • Cancer-associated cachexia can be classified using the model that incorporates age, white blood cell count, FDG uptake of the liver, and visceral and subcutaneous fat can diagnose with an AUC of 0.729. [ABSTRACT FROM AUTHOR]

Purpose: To prospectively investigate age- and gender-related changes in the fast-twitch (tibialis anterior, TA) and slow-twitch (soleus, SOL) skeletal muscle of healthy rats and volunteers and to compare the exercise-related difference in health volunteers with T1 ρ magnetic resonance imaging (MRI).Materials and Methods: In all, 18 rats and 70 humans were involved in this study. For the animal study, T1 ρ relaxation times were measured in the TA and SOL rat muscle with a 3.0T MRI scanner and compared to histological data. For the human study, three groups (young, middle-aged, and elderly) of volunteers underwent T1 ρ MRI scans (3.0T) of their calves. To further differentiate the human scans, 18 volunteers were recruited, half of them (n = 9) routinely trained with high-intensity sports, while the other half (n = 9) with no physical training. Statistical analysis was performed via paired t-test, independent-sample t-test, and analysis of variance (ANOVA). Correlations between T1 ρ and age/gender/physical endurance were calculated.Results: The average T1 ρ relaxation times of the TA and SOL of female rats were higher than that of male rats (P < 0.001). The T1 ρ relaxation time of TA was significantly lower compared to SOL (P < 0.001). A significant linear correlation was observed between T1 ρ and the type I slow-twitch fiber proportion (%) in SOL (R2  = 0.837, P < 0.001). Similarly, in human studies the average T1 ρ relaxation times of TA were significantly lower than SOL for all age groups (P < 0.001). The higher T1 ρ relaxation times of TA and SOL in the elderly volunteers (P < 0.001) and in the females (P < 0.05) indicated significant age- and gender-dependent differences. In high-intensity sports groups, the higher T1 ρ in SOL (P < 0.01) and lower in TA (P < 0.05) were observed compared with the control group.Conclusion: This study demonstrated that T1 ρ MRI can be used to display the differences in fast- and slow-twitch skeletal muscle as well as potentially age-, gender-, and exercise-related differences.Level Of Evidence: 2 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:61-70. [ABSTRACT FROM AUTHOR]

Approximately half of all patients with hepatocellular carcinoma (HCC) develop cachexia during the course of the disease. It is important to be able to predict which patients will develop cachexia at an early stage.To develop and validate a nomogram based on the magnetic resonance imaging (MRI) features of HCC and body composition for potentially predicting cachexia in patients with HCC.A retrospective two-center study recruited the pretreatment clinical and MRI data of 411 patients with HCC undergoing abdominal MRI. The data were divided into three cohorts for development, internal validation, and external validation. Patients were followed up for six months after the MRI scan to record each patient's weight to diagnose cachexia. Logistic regression analyses were performed to identify independent variables associated with cachexia in the development cohort used to build the nomogram.The multivariable analysis suggested that the MRI parameters of tumor size > 5 cm (P = 0.001), intratumoral artery (P = 0.004), skeletal muscle index (P < 0.001), and subcutaneous fat area (P = 0.004) were independent predictors of cachexia in patients with HCC. The nomogram derived from these parameters in predicting cachexia reached an area under receiver operating characteristic curve of 0.819, 0.783, and 0.814 in the development, and internal and external validation cohorts, respectively.The proposed multivariable nomogram suggested good performance in predicting the risk of cachexia in HCC patients. [ABSTRACT FROM AUTHOR]