Cine magnetic resonance imaging for evaluation of anatomy and flow relations in infants and children with coarctation of the aorta.

Abstract

Sixteen cine magnetic resonance imaging (MRI) studies were performed in 14 patients aged 1 week to 17 years (mean age, 46 months), who had coarctation of the aorta confirmed at angiography or surgery. Conventional echocardiographic-gated MRI was first performed in axial and rotated sagittal views and was used to identify the slice locations for cine MRI. Cine MRI was performed by gradient-recalled acquisition in steady state with a 300 flip angle, 12-msec echo time, 22-msec pulse repetition time, and a 128 x 256 acquisition matrix. Coarctation anatomy was extremely well defined in all but one patient who had vascular clips at the coarctation repair site. The smallest descending aortic flow diameter on cine MRI showed excellent agreement with angiography (r = 0.90). Lucent jets of high-velocity flow through the site of coarctation were imaged in eight patients, and jet length correlated well with the angiographic severity of coarctation (r= -0.81). Two patients were restudied after surgery, and they exhibited excellent repair and normal flow patterns. Cine MRI provides highresolution imaging of coarctation anatomy with a dynamic spatial and temporal visualization of flow and with excellent detail of vascular anatomy and flow both proximal and distal to the coarctation. (Circulation 1988;78:142-148) It is well recognized that two-dimensional echocardiography can diagnose and estimate the severity of coarctation of the aorta. -3 Adequate imaging of the coarctation site is usually possible in neonates, but difficulties can be encountered in older patients or in patients after surgery in whom the distance between the ultrasound transducer and the descending aorta is greater and in whom the image resolution is poorer. Doppler ultrasound has further enhanced the noninvasive assessment of these patients,4,5 and favorable results in predicting pressure gradients across the coarctation have been reported.5-7 However, the pressure gradient measured across a coarctation will not necessarily reflect the degree of obstruction since it is dependent on a number of other factors including From the

Magnetic Resonance Imaging Predictors of Coarctation Severity

“…A practical advantage of these findings is that both 3D MRA of the thoracic aorta and PVC-MRI flow analysis are established MRI techniques, are commonly used in clinical practice, and require relatively short acquisition and imageprocessing times. 9,[13][14][15][16][23][24][25][26] Moreover, both techniques have been evaluated in patients with CoA and were found to reliably assess aortic morphology and collateral vessels and to accurately quantify flow in the descending aorta. 9,13 Assessment of coarctation severity presents a clinical challenge.…”

“…Several studies found good correlations between coarctation diameter by MRI and x-ray angiography. 10,14,15 For example, Riquelme and colleagues 14 showed a correlation coefficient of 0.99 between gradient echo cine MRI and angiography, whereas Simpson et al 15 and Mendelsohn et al 10 reported correlation coefficients of 0.9 and 0.91, respectively. Other groups have focused on the percent increase in descending aorta flow from collateral vessels to assess coarctation severity.…”

“…Patients with cardiac index Ͻ2.2 L · min Ϫ1 · m Ϫ2 at catheterization (Fick method) and those with incomplete CMRI flow data were excluded. To determine normal dimensions of the thoracic aorta based on contrast-enhanced 3D MRA, 20 consecutive patients with a similar age distribution and normal aortas were studied (age 15 …”

“…12 Cardiac magnetic resonance imaging (CMRI) provides an accurate assessment of the anatomic characteristics of CoA and collateral blood vessels. 5,[13][14][15] Prior investigations on CMRI assessment of CoA severity compared the anatomic features and the extent of collateral blood flow with coarctation diameter measured by x-ray angiography, 10,15 blood pressure measurements by sphygmomanometry, 9 and Doppler assessment of flow velocity. 16 The ability of CMRI to predict the hemodynamic severity of CoA as measured by cardiac catheterization remains unclear.…”

Congenital Heart Disease. Evaluation of Anatomy and Function by MRI

“…This diagnosis can be made in infants using routine TTE, but in older or postoperative patients the area of interest is not easily accessible with TTE. Conventional MRI often already provides essential information [2,6,7,15,33,83,91,101,110,119]. Useful diagnosis and followup of coarctation with MRI does not necessarily require the combination of a high-field machine and the latest pulse sequences, but the estimation of the severity of the stenosis from the size of the signal void on GRE images appears hazardous [103].…”