Fig. 4.1
Single frontal view of the chest in a 15-year-old male shows orthopedic bars in place along the anterior chest from pectus excavatum repair in a patient with Marfan syndrome. Notice the small right apical pneumothorax (arrow).
A posterior vertebral body scalloping sign can be seen with dural ectasia. This finding, characteristic of Marfan syndrome, is evidenced on lateral lumbar spine radiographs as vertebral body posterior aspect concavity exaggeration [3]. This is a nonspecific imaging appearance and can be seen with increased transspinal pressure secondary to an expansile mass, chronic increased intraspinal pressure secondary to communicating hydrocephalus, intervertebral body disc herniation (rare), neurofibromatosis, Ehlers–Danlos syndrome, ankylosing spondylitis, achondroplasia, Morquio syndrome, Hurler syndrome, and acromegaly [3]. When the radiographic finding indeed represents dural ectasia, the common differential is pared to Marfan syndrome, Ehlers–Danlos syndrome, neurofibromatosis, and ankylosis spondylitis [4].
Another radiographic finding is protrusio acetabuli, diagnosed on anteroposterior (AP) pelvic radiographs by acetabular protrusion at least 3 mm beyond the ilio-ischial line [5].
4.2.2 ECG Findings
Electrocardiographic abnormalities can be seen in up to 50% of pediatric Marfan syndrome patients [6]. The arrhythmias, which tend to be under-recognized, include atrial fibrillation and ventricular arrhythmias that can lead to sudden death. There is a questionable link with Wolff–Parkinson–White syndrome.
4.2.3 CT Findings
CT scans can be used to evaluate the aortic root for dilatation when transthoracic echocardiogram is insufficient. CT also can be used to evaluate protrusio acetabuli and to detect lumbosacral dural ectasia; there is no accepted first-line imaging modality for this purpose.
Additional findings that can be evaluated include apical blebs, pneumothorax, and mitral valve prolapse. CT scans are good for evaluation of dissection in the acute setting, and coronary CT angiography (CTA) can be used in patients with dissection to evaluate for effect on the coronary arteries (Fig. 4.2) [7].
Fig. 4.2
Axial (a) and sagittal (b) views from a CT angiogram of the chest in an 18-year-old female shows a dissection of the ascending (1) and descending (3) thoracic aorta in a patient with Marfan syndrome. Notice the extension of the pneumothorax into the brachiocephalic artery (2)
4.2.4 MRI Findings
MRI is best utilized to assess for chronic dissection, and it should be used in any patient where the aortic root size is more than 150% of the mean for the patient’s body surface area [8]. A phase contrast cardiac study can be used for quantification of aortic or mitral regurgitation [7]. MR cine imaging can show mitral valve prolapse.
MRI can be used to evaluate the aortic root when transthoracic echocardiogram is insufficient. Double inversion recovery images can detect aortic root dilatation. MRI also can be used to evaluate protrusio acetabuli and to detect lumbosacral dural ectasia (Fig. 4.3); there is no accepted first-line imaging modality for this purpose.
Fig. 4.3
Cardiac MRI (three-chamber view) shows mitral valve prolapse (arrows) in a patient with Marfan syndrome
Additional findings that can be evaluated by MRI include apical blebs, pneumothorax, and mitral valve prolapse.
4.2.5 Ultrasonographic Findings
M-mode echocardiogram may show systolic posterior motion of the mitral valve leaflets [7], separate from flat systolic motion, which can be seen with dilated cardiomyopathies. Biconvex enlargement of the sinus of Valsalva is suggestive.
Two-dimensional (2D) echocardiography is useful in evaluating the cardiac valves, particularly the mitral valve; mitral valve prolapse is observed in up to 90 % of patients [9]. It also is used to evaluate left ventricular function and look for enlargement, and to evaluate left atrial size.
Evaluation of the aortic root size is important. Reliable measurements of the aortic root should be plotted against age-adjusted normograms, including the sinus of Valsalva, sinotubular junction, and ascending aorta. The normograms are controversial, however, because the comparison data are not collected from tall patients with thin body habitus in whom Marfan syndrome has been excluded [6].
For patients with a dilated aortic root, describe the appearance. There is increased risk of dissection with diffuse dilatation and loss of the sinotubular junction [6]. The aortic root is enlarged once it measures greater than 1.9 cm/m2 of body surface area [8]. The prominent fibrillin component of the myocardium leads to paradoxical septal motion, and it is necessary to exclude pseudo pericardial effusion [1].
Pulsed Doppler is used to detect and grade the severity of mitral regurgitation and aortic regurgitation.
Transesophageal echocardiography is used for the distal ascending aorta, descending aorta, and prosthetic valves.
Cardiac catheterization is not typically utilized for diagnosis but it is more commonly used in patients with mitral valve prolapse to exclude coronary artery disease. Intracardiac pressures and cardiac output are usually normal in mitral valve prolapse that is uncomplicated, but these values become abnormal as the mitral valve prolapse becomes more severe [1].
4.2.6 Angiography
Angiography can be used to evaluate aortic dissection , but there is a risk of arterial puncture [7].
4.2.7 Imaging Recommendations
The best imaging tool in patients with acute symptoms is CT to evaluate for dissection or rupture [7]. For surveillance, a yearly transthoracic echocardiogram should be performed, with consideration of a transesophageal echocardiogram or MRI [1]. Cardiac MRI is useful for mitral regurgitation and aortic regurgitation, and can be used for mitral valve prolapse [7]. Mitral valve prolapse can also be evaluated by echocardiography, more commonly starting with a transthoracic approach. Echocardiography will also identify aortic root and valvular pathology.
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