Clinical Research Of High-Resolution Magnetic Resonance Coronary Wall Imaging

PartⅠComparision of breath-holding volume-targeted with navigator-gated whole-heart coronary magnetic resonance angiographyObjective To compare the abilities of breath-holding volume-targeted with navigator-gated whole-heart coronary magnetic resonance imaging to visualize coronary segments and the qualities of images obtained by both acquisition methods, in order to explore which one is more suitable as a scout scan for mangnetic resonance coronary vessel wall imaging.Methods Coronary MRA were perfomed in 26 healthy volunteers enrolled at 1.5T by both acquisition methods. Coronary arteries were divided into 9 segments according to the AHA criterion. All of the images were graded by two MR doctors.The satisfactory rate and achievement rate of visualization of coronary segments were calculated.50 images obtained by both methods were chosen respectively from the images testified as satisfactory. SNR and CNR of these images were measured and calculated, then compared the qualities of the images from both methods. Results All the examinations were completed successfully. The total satisfactory rate of visualization of coronary segments by volume-targeted was 91.9%, and the achievement rate was 96.2%. For comparison, those of navigator whole-heart were 96.6% and 100%, respectively. The satisfactory rate of volume-gated was lower than that of whole-heart (p<0.05), but there was no obvious difference in the achievement rate between both methods (p>0.90). Both the SNR and coronary blood pool/myocardium CNR of images obtained by volume-targeted were superior to those of images obtained by whole-heart acquisition. Conclusions Both of the two acquisition methods have merits and demerits, but the difference of the abilities to visualize the main coronary segments between the two methods is not significant. But volume-targeted is more suitable as a scout scan for coronary vessel wall imaging because of higher quality images and more and more easy and convenient operation.PartⅡHigh-resolution Magnetic Resonance Imaging of Coronary Vessel WallObjective To probing the feasibility to depict the micro anatomic structures of coronary vessel wall by high-resolution MR vessel wall imaging. Methods 20 healthy volunteers were selected to undergo high-resolution MR coronary vessel wall imaging at 1.5T. All of the images obtained were scored by two veteran MR doctors under negotiation. Signal-to-noise rate and contrast-to-noise rate of coronary vessel wall-lumen and wall-surroundings were measured on images scored≥2. Inner diameters, cross-sectional lumen area and wall thickness of coronary vessels were measured on the higher scored cross-section images. Results 18 volunteers completed the examinations successfully and 97 images were obtained. Of all the images,59 were from RCA with 2.08 average score and 38 were from LCA with 1.39 average score. The SNR and CNR of coronary vessel wall/lumen and wall/surroundings were 39.8±18.4,38.3±15.5 and 37.2±16.9, respectively. Measurements were performed on the RCA vessel wall cross-sectional images with scores≥2. We achieved the result that the average inner diameter and area of the lumen and the average thickness of vessel wall of proximal segment of RCA were 3.6±0.5mm,9.7±3.2mm2 and 1.1±0.2mm, respectively, which basically matched with literatures. Conclusions High-resolution MR imaging of coronary vessel wall, which have great prospect of application at the clinical diagnose and research of coronary diseases, can provide high quality images and demonstrate micro anatomic structure of coronary arteries wall, and can also quantitively measure and analyze correlative data.PartⅢhigh-resolution magnetic coronary vessel wall imaging of coronary atherosclerosisObjective To explore the feasibility to visualize the abnormality of coronary wall in the patients with coronary heart disease by high-resolution magnetic resonance coronary vessel wall imaging Methods 18 patients of coronary heart disease with coronary arteries stenosis proved by selective coronary angiography or coronary CT angiography were collected. High-resolution magnetic resonance coronary wall imaging was performed on these patients at 1.5T scanner. Cross-sectional wall images of stenotic segments and adjacent non-stenotic segments obtained were assessed by two MRI doctors under negotiations. The images which were regarded as dissatisfactory visualization were ruled out. The measurements of wall thickness, luminal diameters and cross-sectional area of both stenotic and non-stenotic segments were performed and compared on images regarded as satisfactory visualization. Results 15 of 18 patients completed the examinations successfully. There were totally 26 stenotic coronary segments proved by selective coronary angiography and CT angiography, and 34 satisfactory images (17 from stenotic and non-stenotic segments respectively) were obtained from these 15 patients. The measurements of wall thickness, luminal diameters and cross-sectional area of stenotic coronary segments were 1.9±0.6mm,2.9±0.5mm and 6.5±2.2mm2,respectively. Compared with non-stenotic segments (1.0±0.2mm for wall thickness,3.5±0.6mm for luminal diameters and 8.7±2.5mm2 for cross-sectional area), the wall thickness of stenotic was increased (p<0.01), and luminal diameters and cross-sectional area of stenotic segments were decreased (p<0.05). All of these differences had statistical significance. On MR wall images, the wall of stenotic segments thickened locally (64.7%) or diffusely (35.3%). The thickened wall presented as hyperintensity (23.5%), isointensity (29.4%), hypointensity (5.9%) or mixed intensity (41.2%). Conclusions High-resolution magnetic resonance coronary vessel wall imaging, which is a potential imaging modality for coronary artery disease, can visualize the abnormalities of the wall and lumen of atherosclerotic coronary arteries and provides predominant data supports to the diagnosis of coronary heart disease. However, the achievement ratio of this examination is relatively lower, and the spatial resolution of the images still needs to be improved.