Thin-section, three-dimensional (3D) gradient-echo magnetic resonance imaging of the coronary arteries was performed without and with retrospective respiratory gating in 12 healthy volunteers and one patient. In all examinations, results were improved with gating. In five of seven volunteer examinations, coronary artery delineation on images reconstructed by using the least-squares method for motion detection with navigator echoes was found to be equal to that obtained by using edge detection. Images in five other volunteers covered the entire heart with multiple overlapping 3D slabs. The arteries were segmented from the background and could be viewed from any orientation. The lengths of contiguously visible vessels were as follows: left main coronary artery, 11.5 mm +/- 0.4 (mean +/- standard deviation); left anterior descending branch, 115.9 mm +/- 19.7; left circumflex branch, 97.2 mm +/- 12.5; and right coronary artery, 125.9 mm +/- 18.8. This respiratory gating technique clearly improved depiction of the coronary arteries.

A volume-targeted contrast agent-enhanced breath-hold coronary magnetic resonance angiographic technique was optimized and evaluated in 16 volunteers. Substantial increases in coronary signal-to-noise ratio, contrast-to-noise ratio, lengths of depiction, and vessel sharpness were observed on enhanced images. The imaging approach with two 20-mL injections of contrast agent covers the left and right coronary arteries in two breath holds and is a promising method for coronary imaging.

Isoflurane caused cross-frequency coupling between α and slow δ waves. Increasing isoflurane concentration slowed the α frequencies where the coupling had occurred. This phenomenon of α-δ coupling suggests that slow cortical oscillations organize the higher α band activity, which is consistent with other studies in natural sleep.

Objectives While patients with HIV infection have an elevated stroke risk, ultrasound studies of carotid artery wall thickness have reported variable results. We hypothesized that subjects with HIV infection on chronic highly active antiretroviral therapy (HAART) would have increased carotid artery wall thickness by magnetic resonance imaging (MRI). Methods This cross-sectional study compared carotid artery wall thickness between 26 individuals infected with HIV on chronic HAART and 20 controls, without HIV infection but with similar cardiovascular risk factors, using 3.0-T noncontrast MRI. Inclusion criteria included male gender, age 35–55 years, and chronic HAART (≥3 years) among HIV-seropositive subjects; those with known cardiovascular disease or diabetes were excluded. Results Between subjects with HIV infection and controls, there were no differences in mean (± SD) age (47.8 ± 5.0 vs. 47.8 ± 4.7 years, respectively; P = 0.19) or cardiovascular risk factors (P > 0.05 for each). Mean (± SD) wall thickness was increased in those with HIV infection vs. controls for the left (0.88 ± 0.08 vs. 0.83 ± 0.08 mm, respectively; P = 0.03) and right (0.90 ± 0.10 vs. 0.85 ± 0.07 mm, respectively; P = 0.046) common carotid arteries. Among individuals with HIV infection, variables associated with increased mean carotid artery wall thickness included lipoaccumulation [+0.09 mm; 95% confidence interval (CI) 0.03–0.14 mm; P = 0.003], Framingham risk score ≥5% (+0.07 mm; 95% CI 0.01–0.12; P = 0.02 mm), and increased duration of protease inhibitor therapy (+0.03 mm per 5 years; 95% CI 0.01–0.06 mm; P = 0.02). Conclusions Individuals with HIV infection on chronic HAART had increased carotid artery wall thickness as compared to similar controls. In subjects with HIV infection, the presence of lipoaccumulation and longer duration of protease inhibitor therapy were associated with greater wall thickness.

To compare the diagnostic accuracy of coronary magnetic resonance angiography with three-dimensional (3D) trueFISP breath-hold and respiratory gated techniques for the detection of significant coronary artery stenosis. 15 patients who recently underwent elective coronary angiogram were studied and a total of 60 arteries and 48 arteries were assessed by breath-hold and respiratory gated 3D trueFISP techniques, respectively. The image quality, length of artery visualized and the presence or absence of significant coronary artery stenosis were recorded. 83.3% and 81.7% of the arteries obtained with the respiratory gated and the breath-hold techniques, respectively, had an image quality suitable for further analysis. There was no significant difference in the length of artery visualized. Sensitivity and specificity of 80%, 100% and 75% and 100%, respectively, were obtained with the breath-hold and respiratory gated techniques in detecting significant stenosis in the coronary arteries. Both techniques have moderate sensitivity and high specificity in detection of significant stenosis in the visualized segments of the major coronary arteries. However, they cannot replace conventional coronary angiogram for diagnosing coronary artery disease at present. Further studies are required to evaluate whether breath-hold approach is more efficient, therefore should be performed first and respiratory gated approach reserved for those who cannot breath-hold.