Reorganization of intrinsic functional connectivity in early-stage Parkinson's disease patients with probable REM sleep behavior disorder.

REM sleep behavior disorder (RBD) symptoms in Parkinson's disease (PD) suggest both a clinically and pathologically malignant subtype. However, whether RBD symptoms are associated with alterations in the organization of whole-brain intrinsic functional networks in PD, especially at early disease stages, remains unclear. Here we use resting-state functional MRI, coupled with graph-theoretical approaches and network-based statistics analyses, and validated with large-scale network analyses, to characterize functional brain networks and their relationship with clinical measures in early PD patients with probable RBD (PD+pRBD), early PD patients without probable RBD (PD-pRBD) and healthy controls. Thirty-six PD+pRBD, 57 PD-pRBD and 71 healthy controls were included in the final analyses. The PD+pRBD group demonstrated decreased global efficiency (t = -2.036, P = 0.0432) compared to PD-pRBD, and decreased network efficiency, as well as comprehensively disrupted nodal efficiency and whole-brain networks (all eight networks, but especially in the sensorimotor, default mode and visual networks) compared to healthy controls. The PD-pRBD group showed decreased nodal degree in right ventral frontal cortex and more affected edges in the frontoparietal and ventral attention networks compared to healthy controls. Furthermore, the assortativity coefficient was negatively correlated with Montreal cognitive assessment scores in the PD+pRBD group (r = -0.365, P = 0.026, d = 0.154). The observation of altered whole-brain functional networks and its correlation with cognitive function in PD+pRBD suggest reorganization of the intrinsic functional connectivity to maintain the brain function in the early stage of the disease. Future longitudinal studies following these alterations along disease progression are warranted.

Association between resting myocardial work indices and stress myocardial perfusion in patients with angina and non-obstructive coronary artery disease.

Background: Myocardial work (MW) indices and longitudinal strain (LS) are sensitive markers of early left ventricular systolic dysfunction. Stress computed tomography myocardial perfusion imaging (CT-MPI) can assess early myocardial ischemia. The association between resting MW indices and stress myocardial perfusion remains unclear. This study compares resting MW indices with LS to assess stress myocardial perfusion in angina patients with non-obstructive coronary artery disease (CAD). Methods: Eighty-four patients who underwent resting echocardiography, coronary computed tomography angiography, and stress CT-MPI were reviewed. Seventeen myocardial segments were divided into three regions according to the epicardial coronary arteries. Global indices included global longitudinal strain (GLS), global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). Regional indices included regional longitudinal strain (RLS), regional work index (RWI), and regional work efficiency (RWE). Reduced global perfusion was defined as an average stress myocardial blood flow (MBF) <116 mL/100 mL/min for the whole heart. Reduced regional perfusion was defined as an average stress MBF <116 mL/100 mL/min for the coronary territories. No patients demonstrated obstructions in the epicardial coronary arteries (stenosis diameter <50%). The MW indices and LS were compared. Receiver operating characteristic curves were constructed and logistic regression analyses were used to investigate the predictors of reduced myocardial perfusion. Results: Patients with reduced stress perfusion demonstrated reduced GLS, GWI, GCW, and GWE (P<0.05) and increased GWW (P<0.05). After adjustment for age and sex, GWE was still independently associated with reduced myocardial perfusion (odds ratio =0.386, 95% confidence interval: 0.214-0.697; P<0.05). Receiver operating characteristic curves reflected the good diagnostic ability of GWE and its superiority to GLS (area under the curve: 0.858 vs. 0.741). The optimal cutoff GWE value was 95% (sensitivity, 70%; specificity, 90%). Regions with lower stress perfusion showed lower RLS, RWI, and RWE (P<0.05). The optimal cutoff value of RWE for predicting reduced regional perfusion was 95%, with an area under the curve of 0.780, a sensitivity of 62%, and a specificity of 83%. Conclusions: Resting MW indices perform well in assessing global and regional stress myocardial perfusion in angina patients with non-obstructive CAD, and GWE is superior to GLS in the global evaluations.

Low injection rate for 3D moving-table bolus-chase MR angiography: initial experience with 3-T imaging to allay venous contamination in the calf.

OBJECTIVE: The purpose of this study was to evaluate the potential for improving the image quality of 3D bolus-chase peripheral MR angiography by injecting contrast medium at a slow rate. SUBJECTS AND METHODS: Using similar imaging parameters in all cases, we performed bolus-chase MR angiography of the abdominal and lower limb arteries of 80 patients. The injection protocol for 40 patients had three parts: 20 mL of gadopentetate dimeglumine at 2 mL/s, 8 mL of gadopentetate dimeglumine at 1 mL/s, and 20 mL of saline solution at 1 mL/s. For the other 40 patients, the injection protocol was 20 mL of gadopentetate dimeglumine at 1.2 mL/s, 8 mL of gadopentetate dimeglumine at 0.7 mL/s, and 20 mL of saline solution at 0.7 mL/s. Using independent Student's t tests between groups, we compared signal-to-noise and contrast-to-noise ratios in the abdomen and pelvis, the thigh, and the calf. Arterial visibility and venous contamination on 3D images of the calf were graded and compared. RESULTS: The lower injection rate increased arterial visibility (p < 0.001), reduced venous contamination in the calf (p < 0.001), and increased the contrast-to-noise ratio in the calf (p < 0.001). At the upper levels, signal-to-noise and contrast-to-noise ratios did not differ between the two groups. CONCLUSION: At 3-T MRI, a lower injection rate may alleviate venous contamination and increase arterial visibility in the calf while signal-to-noise and contrast-to-noise ratios at higher levels are maintained.

[Assessment left and right ventricular functions by cine magnetic resonance imaging in healthy volunteers].

OBJECTIVE: Left and right ventricular functions were assessed by cine MR imaging in comparison with echocardiography in healthy volunteers. METHODS: A total of 36 healthy volunteers were examined with breath-hold true FISP cine MR imaging sequence and amended localize methods for left and right ventricular functions. Echocardiography (echo) was also performed in these volunteers. RESULTS: (1) left ventricular global function parameters obtained by MR were as follows: EDV (101.3 +/- 19.2) ml, ESV (42.1 +/- 13.3) ml, SV (69.2 +/- 9.8) ml, EF (59.1 +/- 7.2)%; Right ventricular global function as follows: EDV (118.9 +/- 27.1) ml, ESV (57.6 +/- 16.1) ml, SV (61.2 +/- 12.7) ml, EF (51.9 +/- 4.5)%. (2) EDV measured by MR and echo was similar and ESV measured by MR was significantly higher and the rest parameters were lower than that by echo. There was a good correlation (r = 0.66 - 0.80, P < 0.05) on all parameters obtained by MR and echo. CONCLUSION: The present study suggests that cine MR imaging is well applicable to left and right ventricular function and RV volume measurements.