OBJECTIVES Magnetic resonance imaging (MRI) of the vessel wall enables determination of luminal area, vessel wall thickness, and atherosclerotic plaque characteristics. For clinical application,... Show moreOBJECTIVES Magnetic resonance imaging (MRI) of the vessel wall enables determination of luminal area, vessel wall thickness, and atherosclerotic plaque characteristics. For clinical application, high spatial resolution, derived from optimal signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), is paramount. Vessel wall MRI is expected to benefit from higher magnetic field strength. Therefore, the purposes of the present study were to develop an ultrahigh-field 7-T MRI hardware and protocols for vessel wall imaging of the carotid artery and to compare quantitative parameters of vessel wall morphology and image quality between 3-T and 7-T MRI. MATERIAL AND METHODS Eighteen volunteers (11 men and 7 women; mean [SD] age, 29 [7] years) underwent MRI examinations at 7 T (using a custom-built surface transmit/receive coil of 15-cm diameter) and at 3 T (using a commercial phased-array coil with 2 flexible oval elements, 14 × 17 cm each). Magnetic resonance imaging of the left common carotid artery vessel wall was performed at 7 T with identical in-plane resolution as that of 3-T MRI (0.46 × 0.46 mm), providing transverse T1- and T2-weighted images. Blinded analysis of morphologic measurements (luminal area and vessel wall area), SNR for vessel wall (SNRVW), and the CNR between the lumen and the vessel wall were compared between 7 and 3 T. RESULTS Morphologic carotid vessel wall measurements were comparable between 7 and 3 T for both T1-weighted images (luminal area: intraclass correlation [ICC], 0.81 and vessel wall area: ICC, 0.84) and T2-weighted images (luminal area: ICC, 0.97 and vessel wall area: ICC, 0.92). At 7 T, SNRVW and CNR were significantly higher compared with 3-T MRI for both T1- (P < 0.001) and T2-weighted images (P < 0.05), with gain factors ranging from 1.3 to 3.6. CONCLUSIONS Ultrahigh-field 7-T MR carotid vessel wall imaging is feasible. 7-T MRI of the common carotid artery has comparable accuracy for determining luminal area and vessel wall area and has improved SNRVW and CNR compared with 3-T MRI. Therefore, ultrahigh-field 7-T vessel wall MRI may enable a more detailed assessment of plaque morphology. Show less
PURPOSE: Currently, a multi-contrast protocol, including a combination of five MR-sequences is used as reference standard for morphologic imaging and quantitative measurements of the carotid artery... Show morePURPOSE: Currently, a multi-contrast protocol, including a combination of five MR-sequences is used as reference standard for morphologic imaging and quantitative measurements of the carotid artery vessel wall. The purpose of this study is to investigate the scan-rescan reproducibility together with intra- and inter-observer reproducibility of each of the five MR-sequences. METHODS: Twenty healthy volunteers (55% male, mean age=26 years) underwent repeated MR-examinations (3T-Philips-MRI) of the left carotid artery vessel wall with five sequences; T1-TFE, T2-TSE, PD-TSE, T1-TSE and 3D TOF. A standard phased-array coil with two flexible elements of 14cm×17cm was used to obtain nine transverse imaging sections of the left carotid artery with identical in-plane resolution (0.46mm×0.46mm). Reproducibility analysis was performed in 3 slices of the common carotid artery for all sequences. RESULTS: For, scan-rescan reproducibility, intra class correlation coefficients (ICC) were excellent for all sequences and ranged from 0.79 to 0.95. The intra-observer ICC ranged from 0.89 to 0.98 and the inter-observer ICC ranged from 0.84 to 0.96, for both lumen and vessel wall assessment. CONCLUSIONS: By high field MR imaging, vessel wall and lumen area of the carotid artery can be assessed with excellent scan-rescan, intra- and inter-observer reproducibility for all five sequences. Show less
Buckle, T.; Kuil, J.; Berg, N.S. van den; Bunschoten, A.; Lamb, H.J.; Yuan, H.; ... ; Leeuwen, F.W.B. van 2012
Diabetes mellitus type 1 (DM1) is associated with aortic stiffening and left ventricular (LV) diastolic dysfunction, however the relationship between aortic stiffness and LV diastolic dysfunction... Show moreDiabetes mellitus type 1 (DM1) is associated with aortic stiffening and left ventricular (LV) diastolic dysfunction, however the relationship between aortic stiffness and LV diastolic dysfunction in DM1 patients is still largely unknown. The purpose of this study was to evaluate whether an increased aortic stiffness, expressed by increased aortic pulse wave velocity (PWV), is associated with subclinical LV diastolic dysfunction and decreased left atrial (LA) compliance as assessed with speckle tracking strain analysis in patients with DM1. Aortic PWV was assessed with cardiovascular magnetic resonance in 41 DM1 patients. Patients underwent echocardiography for assessment of conventional LV diastolic function indices and LV and LA longitudinal strain and strain rate (SR) assessed with speckle tracking strain analysis. LV SR during the isovolumic relaxation period (SRIVR) and LA strain were recorded and the E-wave velocity to SRIVR velocity ratio (E/SRIVR) was calculated. Independent samples t test and multivariate linear regression analyses were used for statistical analyses. Aortic PWV significantly correlated with SRIVR (β = -0.71, p < 0.001), E/SRIVR (β = 0.61, p = 0.002) and LA strain (β = -0.47, p = 0.014), but not with conventional echocardiographic markers of diastolic function (all p > 0.10). In DM1 patients, aortic stiffness is inversely associated with sensitive markers of LV diastolic function and decrease in LA compliance as measured with echocardiographic speckle tracking strain analysis. Show less
BACKGROUND: In patients with Marfan syndrome (MFS), increased aortic wall stiffening may lead to progressive aortic dilatation. Aortic Pulse Wave Velocity (PWV), a marker of wall stiffness can be... Show moreBACKGROUND: In patients with Marfan syndrome (MFS), increased aortic wall stiffening may lead to progressive aortic dilatation. Aortic Pulse Wave Velocity (PWV), a marker of wall stiffness can be assessed regionally, using in-plane multi-directional velocity-encoded MRI. This study examined the diagnostic accuracy of regional PWV for prediction of regional aortic luminal growth during 2-year follow-up in MFS patients. METHODS: In twenty-one MFS patients (mean age 36±15years, 11 male) regional PWV and aortic luminal areas were assessed by 1.5T MRI. At 2-year follow-up, the incidence of luminal growth, defined as mean luminal diameter increase >2mm was determined for five aortic segments (S1, ascending aorta; S2, aortic arch; S3, thoracic descending aorta, S4, supra-renal and S5, infra-renal abdominal aorta). Regional PWV at baseline was considered increased when exceeding age-related normal PWV (healthy volunteers (n=26; mean age 30±10years, 15 male)) by two standard-errors. Sensitivity and specificity of regional PWV-testing for prediction of regional luminal growth were determined. RESULTS: Regional PWV at baseline was increased in 17 out of 102 segments (17%). Significant luminal growth at follow-up was reported in 14 segments (14%). The specificity of regional PWV-testing was ≥78% for all aortic segments, sensitivity was ≤33%. CONCLUSIONS: Regional PWV was significantly increased in MFS patients as compared to healthy volunteers within similar age range, in all aortic segments except the ascending aorta. Furthermore, regional PWV-assessment has moderate to high specificity for predicting absence of regional aortic luminal growth for all aortic segments in MFS patients. Show less
Kroner, E.S.J.; Lamb, H.J.; Siebelink, H.J.; Wall, E.E.; Grond, J. van der; Buchem, M.A. van; ... ; Westenberg, J.J.M. 2012
BACKGROUND Diabetic patients have increased interstitial myocardial fibrosis on histological examination. Magnetic resonance imaging (MRI) T(1) mapping is a previously validated imaging technique... Show moreBACKGROUND Diabetic patients have increased interstitial myocardial fibrosis on histological examination. Magnetic resonance imaging (MRI) T(1) mapping is a previously validated imaging technique that can quantify the burden of global and regional interstitial fibrosis. However, the association between MRI T(1) mapping and subtle left ventricular (LV) dysfunction in diabetic patients is unknown. METHODS AND RESULTS Fifty diabetic patients with normal LV ejection fraction (EF) and no underlying coronary artery disease or regional macroscopic scar on MRI delayed enhancement were prospectively recruited. Diabetic patients were compared with 19 healthy controls who were frequency matched in age, sex and body mass index. There were no significant differences in mean LV end-diastolic volume index, end-systolic volume index and LVEF between diabetic patients and healthy controls. Diabetic patients had significantly shorter global contrast-enhanced myocardial T(1) time (425±72 ms vs. 504±34 ms, P<0.001). There was no correlation between global contrast-enhanced myocardial T(1) time and LVEF (r=0.14, P=0.32) in the diabetic patients. However, there was good correlation between global contrast-enhanced myocardial T(1) time and global longitudinal strain (r=-0.73, P<0.001). Global contrast-enhanced myocardial T(1) time was the strongest independent determinant of global longitudinal strain on multivariate analysis (standardized β=-0.626, P<0.001). Similarly, there was good correlation between global contrast-enhanced myocardial T(1) time and septal E' (r=0.54, P<0.001). Global contrast-enhanced myocardial T(1) time was also the strongest independent determinant of septal E' (standardized β=0.432, P<0.001). CONCLUSIONS A shorter global contrast-enhanced myocardial T(1) time was associated with more impaired longitudinal myocardial systolic and diastolic function in diabetic patients. Show less
