MRA reveals peripheral aneurysms in Kawasaki: allows more aggressive therapy. (Clinical Rounds).
Magnetic resonance angiography (MRA) also provides a sensitive, noninvasive means of identifying and evaluating the severity of coronary-artery and giant coronary-artery aneurysms and their responses to treatment, reducing the need for serial radiographic coronary angiography, said Dr. Myones.
Transthoracic echocardiography is the usual technique used for identifying the occurrence and course of coronary artery aneurysms in Kawasaki patients. However, this is not routinely performed to confirm the presence of lesions in peripheral arteries in these patients unless there is evidence on physical exam of peripheral aneurysm formation.
"This obviously is not very sensitive," he noted.
By comparison, whole-body MRA not only provides clear images of coronary-artery aneurysms, but also identifies peripheral lesions occurring outside the viewing field of standard sonographic imaging studies, said Dr. Myones.
Peripheral aneurysms that go undetected can contribute to persistent symptoms, unstable hemodynamics, and long-term complications, and should therefore be found and monitored, said Dr. Myones, director of research for the pediatric rheumatology center at Texas Children's Hospital in Houston.
In a prospective investigation of coronary- and peripheral-artery visualization in infants with Kawasaki disease, five clinically unstable patients aged 3-9 months in whom peripheral aneurysms were identified on physical exam underwent whole-body MRA. The imaging objective was to define the extent of peripheral-arterial involvement, Dr. Myones said.
Two MRA techniques were used: time-resolved, contrast-enhanced whole-body MRA with sensitivity encoding acceleration; and noncontrast coronary three-dimensional MRA with respiratory navigation. The imaging studies identified multiple arterial aneurysms of the torso and limbs in all five infants.
Importantly, "only a few of the lesions had been suspected based on physical examination," Dr. Myones commented.
The coronary MRA images revealed coronary-artery aneurysms and giant coronary-artery aneurysms in all of the infants, which correlated with echocardiography results.
Treatment for all five infants included intravenous immunoglobulin and pulsed steroids because of their age, hemodynamic status, and persistent symptoms.
Low-molecular-weight heparin and oral pentoxifylline were also used because of the severity of the coronary lesions, coincident coagulopathy, and the presence of peripheral arterial disease.
Subsequent MRA studies were performed in three of the infants to assess the status of the lesions and monitor treatment response. "In all three patients, serial MRAs showed partial regression of the [peripheral, coronary-artery, and giant coronary-artery] aneurysms," said Dr. Myones.
The study results suggest that whole-body MRA is useful in Kawasaki disease because it can help visualize the occurrence of coronary and peripheral lesions as well as "guide more aggressive therapy with steroids, anticoagulants, and antiplatelet/vasodilator drugs," he said.
However, "because of the costs involved, only patients at high risk for aneurysm [peripheral and coronary] should be scanned. These include young infants under age 1, patients with a delay in diagnosis and treatment, patients with repeat episodes, and patients with a poor response to standard therapy," he told this newspaper.
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|Title Annotation:||magnetic resonance angiography|
|Date:||Jul 1, 2003|
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