ABSTRACT
The objective of this study was the feasibility of imaging hemodialysis fistulae with magnetic resonance angiography (MRA). MRA was performed in eight Brescia-Cimino fistulae and seven goretex loop grafts, five of which were stenosed and 10 normal. We compared two MRA methods: a 2D magnetization prepared turbo field echo (MPTFE) and a 3D phase contrast (PC) sequence. Digital subtraction angiography served as the gold standard. MPTFE MRA provided satisfactory quality images of the entire fistula in 14 out of 15 cases, and PC MRA in 9 of 15 cases (p < .05). MPTFE MRA identified all eight stenoses with one false-positive result. PC MRA identified seven of eight stenoses with two false positives. It is feasible to obtain diagnostic images of dialysis fistulae with MRA.
Subject(s)
Arteriovenous Shunt, Surgical , Blood Vessel Prosthesis , Graft Occlusion, Vascular/diagnosis , Magnetic Resonance Angiography/methods , Polytetrafluoroethylene , Renal Dialysis , Angiography, Digital Subtraction , Feasibility Studies , Humans , Image Processing, Computer-AssistedABSTRACT
BACKGROUND: Regional variability in systolic and diastolic cardiac function occurs in most cardiac disorders. The influence of this regional functional heterogeneity on global function is not well understood and is difficult to study with the common imaging modalities. METHODS: A midventricular short axis slice of the left ventricle was obtained with ECG-triggered magnetic resonance imaging in eight infarct patients and 10 control volunteers. The variation in wall thickness and slice cavity volume during the cycle was studied using the centreline method. RESULTS: The peak filling rate was significantly decreased in the infarct group (96 versus 58 cm3/s, P < 0.005). In addition, a small contribution of other parameters, such as the time to end systole, the isovolumic relaxation time, and the duration and extent of early filling, was also shown by linear discriminant analysis. Analysis of the regional parameters demonstrated an increased asynchronicity of contraction (64 versus 37 ms, P < 0.01) as well as relaxation (88 versus 51 ms, P < 0.01) in patients with myocardial infarction. On comparison of the anterior (infarcted) and inferior (non-infarcted) parts of the left ventricle, the difference was present only in the infarct region. CONCLUSION: Magnetic resonance imaging of the heart allows evaluation of the relationship between regional differences in wall motion dynamics and global parameters of diastolic function in infarct patients.
Subject(s)
Myocardial Infarction/physiopathology , Ventricular Function , Aged , Diastole , Hemodynamics , Humans , Magnetic Resonance Imaging , Male , Middle Aged , Myocardial Infarction/pathology , Myocardium/pathologyABSTRACT
The objective of this study was the evaluation of the feasibility of magnetic resonance (MR) imaging of the heart with low-dosage dobutamine stimulation for the detection of viability after acute myocardial infarction. Gradient echo MR images were obtained in 37 patients with recent myocardial infarction. Images of wall motion abnormalities and their reaction to low-dosage dobutamine stimulation were analyzed and compared with two-dimensional echocardiograms. Follow-up echocardiography at 3 to 6 months was available in 24 patients. Concordant diagnosis of viability between the two techniques was obtained in 30 (81%) of 37 patients. MR correctly predicted evolution of wall motion in 19 (79%) of 24 patients, a result not significantly different from echocardiography: 20 (83%) of 24. It was concluded that low-dosage dobutamine MR imaging is a safe alternative to echocardiography to predict recovery of wall motion abnormalities after myocardial infarction.
Subject(s)
Dobutamine , Echocardiography , Magnetic Resonance Imaging/methods , Myocardial Infarction/diagnosis , Myocardium/pathology , Dobutamine/administration & dosage , Echocardiography/instrumentation , Echocardiography/methods , Echocardiography/statistics & numerical data , Electrocardiography , Exercise Test/instrumentation , Exercise Test/methods , Exercise Test/statistics & numerical data , Feasibility Studies , Follow-Up Studies , Humans , Magnetic Resonance Imaging/instrumentation , Magnetic Resonance Imaging/statistics & numerical data , Observer Variation , Prognosis , Statistics, NonparametricABSTRACT
Dynamic magnetic resonance (MR) imaging of the left ventricle was performed in 13 patients with acute myocardial infarction and in 11 healthy volunteers. Visual assessment of cine MR video loops correctly located the infarction of 12 of 13 patients. Quantitative analysis of absolute and relative wall thickening, area ejection fraction, and radial shortening fraction accurately distinguished hearts with and without infarction (p < .001). This distinction could also be made using the number of segments with decreased and the number of segments with decreased + increased wall motion (p < .001). Localization of the infarction by quantitative MR methods was limited, probably due to relative low temporal resolution. Combined evaluation of qualitative and quantitative MR imaging data provides useful information on wall motion dynamics after acute myocardial infarction.
