Screening CT Angiography in Fibromuscular Dysplasia
What is the diagnostic yield of a dedicated computed tomography angiography (CTA) protocol of the chest, abdomen, and pelvis in patients with fibromuscular dysplasia (FMD)?
A total of 113 consecutive patients enrolled in an institutional FMD registry who received a tailored CTA protocol between March 2013 and June 2015 were included in this study. Arterial phase contrast-enhanced images were obtained on a dual-source scanner using high pitch and electrocardiogram trigger. Two readers analyzed the images.
Abnormalities including beading, aneurysm, dissection, and stenosis/occlusion were noted in aortic, renal, mesenteric, and iliac distributions. The most commonly affected vessels were the renal arteries (n = 76 [67%]), followed by the lower extremity/iliac arteries (n = 37 [32%]). Aortic abnormalities were less frequently encountered (n = 3 [3%]), including one case with mild dilation (4.2 cm) of the ascending aorta and two cases of dissection involving the descending aorta, one with mild dilation (4.4 cm). Incremental findings beyond those known at patient intake were commonly noted, including new areas of arterial beading (n = 55 [49%]), new aneurysms (n = 21 [19%]), and new dissections (n = 3 [3%]). Reformatted images were crucial, affecting final assessment in 56% of cases evaluated by reader 1 and 36% evaluated by reader 2.
The authors concluded that screening chest, abdomen, and pelvis CTA in patients with FMD showed substantial and incremental diagnostic yield.
This study reports that use of a specialized screening CTA imaging protocol of the aorta and medium branch vessels in patients with FMD yielded useful incremental findings. Furthermore, infrequent abnormalities in the thoracic aorta suggest that screening imaging in this patient population may be more appropriately limited to abdomen and pelvic aorta and branch vessel CTA. It should be noted that reformatted images had a significant effect on final interpretations. Additional studies are needed to validate these findings and assess whether screening CTA can be limited to the abdomen and pelvis in patients with FMD.
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