Three-dimensional Electrocardiographically Gated Variable Flip Angle FSE Imaging for MR Angiography of the Hands at 3.0 T: Initial Experience

Abstract

After institutional review board approval and informed consent were obtained for this HIPAA-compliant investigation, a three-dimensional electrocardiographically gated variable flip angle (VFA) fast spin-echo magnetic resonance (MR) angiography technique was evaluated as an unenhanced method for imaging hand arteries in 13 subjects (including four patients) at 3.0 T; this included evaluation of vessel visualization with warming and cooling in seven subjects. Examinations were evaluated for image quality and vessel conspicuity. Clear separation of arteries from veins was achieved in all subjects, with excellent vessel conspicuity and depiction of stenoses. Warming improved vessel visualization in healthy volunteers. VFA MR angiography is a high-spatial-resolution technique that enables the assessment of vascular reactivity in response to temperature challenge. RSNA, 2009 1 From the Department of Radiology (MRI), New York University Langone Medical Center, 530 First Ave, Basement Schwartz Bldg, New York, NY 10016 (R.P.L., P.S., I.P.A., E.M.H., J.S.B., D.R.S., K.M., Q.C., H.R., V.S. Note: This copy is for your personal, non-commercial use only. To order presentation-ready copies for distribution to your colleagues or clients, use the Radiology Reprints form at the end of this article.I maging is vital in the work-up and management of vascular hand abnormalities, including thromboembolic disease, vasculitides, trauma, and vascular malformations. The standard of reference for hand evaluation is digital subtraction angiography (1). However, digital subtraction angiography has associated risks of puncture site complications, ionizing radiation, and iodine nephrotoxicity and can also be a painful procedure for patients. In addition, vasodilators are frequently required for optimal visualization of the small arteries of the hand, which are highly reactive to noxious stimuli (2). Contrast materialenhanced magnetic resonance (MR) angiography has been advocated as a suitable noninvasive alternative (3-5), but small vessel caliber, relatively slow arterial flow, and short arteriovenous transit times can hamper arterial visualization (1,6). Attempts to shorten imaging times can compromise spatial resolution or signal-to-noise ratio.An unenhanced technique is desirable, particularly in patients with vasculitides or concurrent renovascular disease, in whom renal function may be compromised and nephrogenic systemic fibrosis becomes a potential clinical concern (7). Time-of-flight and phase-contrast techniques have been reported (8) but are limited by long imaging times and limited coverage (1).An electrocardiographically gated spin-echo-based MR angiographic technique was initially described by Wedeen et al (9) and was later adapted into a three-dimensional (3D) single-shot fast spin-echo (FSE) technique by Miyazaki et al (10) on the basis of the principle that black blood images can be obtained in fast-flowing blood with spin-echo sequences.Promising results have been obtained with this technique for the lower extremities (1...

Non‐contrast enhanced MR angiography: Physical principles

“…A modified cardiac-gated 3D FSE NCE-MRA technique using variable flip angles has also been applied in angiography of the hands at 3T incorporating additional flow-dephasing gradients to enhance the depiction of slow-flowing blood in the arteries of the extremities (58). Figure 6 shows an example of cardiac-gated 3D FSE NCE-MRA and x-ray digital subtraction angiography (DSA) on a patient with peripheral occlusive disease.…”

Unenhanced calf MR angiography at 3.0 T using electrocardiography-gated partial-fourier fast spin echo imaging with variable flip angle

“…Compared with a conventional FSE technique with constant flip angle, SPACE uses a modified variable flip angle, which reduces the duration of data acquisition and specific absorption rate (SAR), and permits more efficient imaging at 3.0 T [18,24]. With SPACE, it enables more consistent discrimination of different velocity flow-especially in compromised flow or fast heart rates [17].…”

“…Recently, a modified technique using variable flip angles, which called sampling perfection with application of optimized contrasts using different flip angle evolutions (SPACE) was shown to improve spatial resolution and speed [17]. A latest study using UE with SPACE showed clear demonstration of hand arteries [18].…”

Nonenhanced MR Angiography of the Hand with Flow-Sensitive Dephasing–prepared Balanced SSFP Sequence: Initial Experience with Systemic Sclerosis

“…The segments were subsequently grouped into four region groups: ulna and radius, arches, common digital arteries, and proper digital arteries. The image quality of the angiograms obtained in both subject groups was assessed by using a fi ve-point Likert scale: A score of 1 indicated excellent arterial diagnostic display and differentiation of the arterial vasculature from the background tissue; a score of 2, good diagnostic arterial display without impaired delineation of the vessel structures; a score of 3, fair diagnostic arterial display and delineation of the arterial structures, with exclusion and detection of lesions still possible; a score of 4, poor diagnostic arterial display with inadequate vessel enhancement or severe blurring; and a score of 5, nondiagnostic arterial display ( 26 ).…”

“…The degree of stenosis was semiquantitatively assessed by using a threepoint scale for the control group-grade 0 indicated normal patency; grade 1, apparent narrowing; and grade 2, nonvisualization-and by using a four-point scale for the patient group-grade 0 indicated normal patency; grade 1, less than or equal to 50% luminal narrowing; grade 2, greater than or equal to 51% luminal narrowing; and grade 3, occlusion ( 26 ). When two or more stenoses were present in one segment, the most severe lesion was used for the subsequent assignment of a grade.…”