Comprehensive aortic magnetic resonance (MR) examinations currently include multiple nonenhanced and contrast material-enhanced sequences. The authors hypothesized that the nonenhanced true fast imaging with steady-state precession (FISP) portion alone of their comprehensive imaging protocol would be adequate to confidently confirm or exclude dissection or aneurysm of the aorta. In a retrospective review of 29 comprehensive thoracic aortic MR examinations, nonenhanced true FISP MR imaging alone was 100% accurate for determining the presence or absence of dissection or aneurysm.
The purpose of the study was to implement a three-dimensional (3D) magnetic resonance (MR) angiographic technique with acquisition times on the order of 800 msec with use of a spoiled gradient-echo pulse sequence (repetition time, 1.60 msec; echo time, 0.65 msec) and bolus intravenous injection of contrast material doses as small as 6 mL. High-spatial-resolution conventional MR angiography performed with 30 mL of gadopentetate dimeglumine was the reference standard. As implemented, subsecond 3D MR angiography allowed temporal sampling that was rapid enough to depict short-lived processes, as illustrated in patients with shunts and dissections. With small contrast material doses and subsecond frame rates, it is also possible to measure pulmonary arteriovenous circulation times with this 3D MR angiographic technique.
TrueFISP images depict morphologic and functional abnormalities with greater clarity and provide greater diagnostic confidence than FLASH images-and in a fraction of the time. A specific exception is in the assessment of valve leaflet architecture and cross-sectional area calculation (i.e., bicuspid aortic valves); in these evaluations, FLASH maintains a complementary diagnostic imaging role.
Background and Purpose
Although HIV infection is decreasing in infants and children, there is a steady cohort of perinatally HIV-infected (PHIV) children that are growing older. Increased risk of acute stroke has been reported in PHIV children. Our goal was to evaluate evolution/progression of neuroimaging findings in PHIV youth initially presenting with acute stroke.
Materials and Methods
The medical records of PHIV pediatric patients (n=179) from 1996 to 2010 were reviewed and patients with clinical documentation of acute stroke referred to the neuroradiology service were eligible for the study. Neuroimaging (brain CT, MRI, and MRA) and charts were evaluated; clinical and neuroimaging findings at the initial acute stroke and at the last presentation to the neuroradiology service were documented and analyzed.
Results
Eight PHIV patients with clinical findings of acute stroke referred to the neuroimaging were identified. CT and MRI findings of infarction were found in all (8/8) patients in their first and/or last neuroimaging study; including basal ganglia-thalami (BGT) infarction (7/8), focal cortical infarction (4/8), and internal capsule infarction (4/8). Imaging depicted cortical atrophy (5/8), BGT calcification (3/8), and posterior reversible encephalopathy syndrome, wallerian degeneration, and periventricular white matter hyperintense T2 signal each in one patient. No tumors or infectious masses, cysts or abscesses were identified. Subsequent available neuroimaging revealed progression of the cerebrovascular disease in 7 patients, 5/7 in the absence of new clinical signs or symptoms. Segmental occlusion, narrowing or narrowing/dilatation in the circle of Willis was found in 6/6 patients who underwent MR angiography and fusiform aneurysms were detected in three of them, a saccular aneurysm in one patient.
Conclusion
Asymptomatic progression of cerebrovascular disease was found in PHIV adolescents with prior stroke. These findings may have implications for long term risk and outcomes for this patient population. There should be a low threshold to evaluate for CNS pathology even with minor symptoms in this population. More studies are necessary to determine if there is a benefit from screening of asymptomatic patients.
Arterial injuries in the neck may be secondary to blunt or penetrating trauma. Because of clinical difficulties in early identification of these injuries as well as their potentially catastrophic consequences, imaging is indispensible in the diagnosis of arterial injuries in the neck. Computed tomography angiography (CTA) has become the initial study of choice in management of these patients. We review the clinical and imaging features of vascular injuries of the neck with special emphasis on CTA.
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