Multiparametric MR Imaging of Age-related Changes in Healthy Thigh Muscles.

Purpose To use multiparametric magnetic resonance (MR) imaging to assess for and establish age-related differences in healthy thigh muscles. Materials and Methods Ninety-five subjects (47 men, 48 women; median age, 47 years) with healthy body mass index were grouped according to age: 30-39 years (n = 25), 40-49 years (n = 25), 50-59 years (n = 25), and 60-69 years (n = 20). Multiparametric MR imaging (intravoxel incoherent motion diffusion-weighted, diffusion-tensor, multiecho Dixon, and dynamic contrast material-enhanced MR imaging) was performed at 3.0 T. Two radiologists independently evaluated parametric maps of the anterior, medial, and posterior compartments. Welch-modified one-way analysis of variance and post hoc Dunnet T3 test were used to evaluate differences in apparent diffusion, true diffusion, and pseudodiffusion coefficients; perfusion fraction; fractional anisotropy (FA); fat percentage; volume transfer constant; constant efflux rate from the extravascular-extracellular space to plasma; volume fraction of the extravascular-extracellular space (Ve); incremental area under the curve; and Pearson and Spearman correlation coefficients were used to evaluate relationship strength. Multiple regression analysis was performed to identify independent predictors of age, and interrater reliability was assessed with intraclass correlation coefficients. Results There were significant differences among the age groups in apparent diffusion coefficients (P = .010), true diffusion coefficients (P = .045), FA (P < .001), Ve (P = .029) of the anterior compartment muscles, and fat percentages of all three compartments (P ≤ .001). Moreover, FA (Pearson r = 0.428, Spearman ρ = 0.431; P < .001) and Ve (r = 0.226, P = .030 and ρ = 0.309, P = .003) in the anterior compartment and fat percentages in all three compartments (r = 0.481, 0.475, and 0.573; ρ = 0.515, 0.487, and 0.667; respectively; P < .001) were positively associated with age. Multiple regression analysis showed that age was predictive of fat percentage in the posterior compartment (ß = 0.500, P < .001) and of FA in the anterior compartment (ß = 0.194, P = .042). Interrater reliability was excellent (intraclass correlation coefficient, 0.745-0.992). Conclusion Multiple MR imaging parameters were significantly associated with age in thigh muscles. © RSNA, 2017 Online supplemental material is available for this article.

Factors causing loss of normal Doppler waveform of the left internal jugular vein: evaluation on chest computed tomography.

PURPOSE: To evaluate the presence and causes of left brachiocephalic vein (LBCV) steno-occlusive lesions in patients with loss of normal waveform in Doppler ultrasound of the left internal jugular vein (LIJV). MATERIALS AND METHODS: We performed Doppler ultrasound of both internal jugular veins in 1912 patients who received an implantable venous access port from August 2013 to January 2016. Among them, 106 patients showed loss of normal Doppler waveforms of the LIJV (56 men and 50 women; mean age, 61.4 ± 11.6 years). We retrospectively analyzed the presence and causes of the LBCV steno-occlusive lesions on contrast-enhanced chest computed tomography (CT) images. RESULTS: LBCV steno-occlusive lesions were present in 82 patients (77.4%). The causes of these lesions were anatomic structures (n = 70, 85.4%), tumorous lesions (n = 11, 13.4%), and thrombus (n = 1, 1.2%). The anterior anatomic structures to the LBCV causing stenosis were bony structures (n = 50), right upper lobe (n = 11), and mediastinal fat (n = 9). The posterior anatomic structures to the LBCV resulting in stenosis were right brachiocephalic artery (n = 58), left common carotid artery (n = 7), and aortic arch (n = 5). The tumorous lesions resulting in stenosis were mediastinal lymph node (n = 5), thymic lesions (n = 3), lymphoma (n = 1), lung cancer (n = 1), and bone tumor (n = 1). CONCLUSIONS: It is necessary to suspect steno-occlusive lesion of the LBCV from various causes and to use caution when performing central venous catheterization in cases with loss of a normal Doppler waveform.

Hemorrhagic fever with renal syndrome-related encephalopathy: magnetic resonance imaging findings.

OBJECTIVE: To report the incidence and findings of brain magnetic resonance imaging (MRI) in patients with hemorrhagic fever with renal syndrome (HFRS)-related encephalopathy along with its clinical course. METHODS: Medical records and brain MRI were reviewed from January 2004 to January 2013. The final cohort consisted of 145 patients. Brain MRI findings were correlated with associated clinical stage of disease. RESULTS: The MRI findings associated with clinical course of HFRS-related encephalopathy were posterior reversible encephalopathy syndrome pattern (n=3) in oliguric phase and splenial lesion pattern (n=1) in febrile phase. CONCLUSIONS: Brain MRI findings in HFRS-related encephalopathy may be associated with the clinical course of HFRS.

"Reuse" study of low-tube-voltage CT arterial phase in the spoiled gadoxetic-acid liver MRI.

OBJECTIVES: To compare diagnostic accuracy of gadoxetic acid-enhanced magnetic resonance imaging (MRI) (original set) and original MRI combined with the arterial phase of low-tube-voltage computed tomography (CT) (hybrid set). METHODS: In hybrid set, we substituted the CT arterial phase for MRI arterial phase. Three observers independently interpreted. The accuracy of each image set was evaluated using the alternative-free response receiver operating characteristic method. RESULTS: The mean Az values for original set (0.96±0.01) was higher than that for hybrid set (0.94±0.01), but the difference was not significant (P=.10). CONCLUSIONS: In cases with degradation of magnetic resonance arterial phase, reuse of CT arterial phase might be helpful instead of repeating MRI.