Intracranial Artery Steno-Occlusion: Diagnosis by Using Two-dimensional Spatially Selective Radiofrequency Excitation Pulse MR Imaging

Abstract

Purpose To determine whether magnetic resonance (MR) imaging by using two-dimensional spatially selective radiofrequency (RF) excitation pulses (zoomed MR imaging) is a reliable method for the diagnosis of intracranial artery steno-occlusion compared with full-field-of-view (FOV) MR imaging. Materials and Methods The institutional review board approved this retrospective study and informed consent was waived. From December 2014 to August 2015, 88 patients who underwent both full-FOV MR imaging and zoomed MR imaging for further evaluation of intracranial artery steno-occlusion at prior luminal evaluation were included. Two neuroradiologists independently diagnosed the diseases (atherosclerosis, dissection, moyamoya disease, vasculitis, undetermined diagnosis, and no vascular pathologic condition) based on both clinical information and MR imaging features and assessed diagnosis-related parameters (diameter, length, eccentricity index, eccentricity, signal intensity ratio, vessel wall hemorrhage, and the total number of lesions), as well as image quality parameters (signal-to-noise ratio and image quality scale) with full-FOV MR imaging and zoomed MR imaging. Parametric measurements were compared between full-FOV MR imaging and zoomed MR imaging by using paired t test and McNemar test. The criterion for intermethod reliability was that the upper limit of the 95% confidence interval (CI) in the difference of agreement was less than 10% based on a noninferiority test. Results The pooled agreement for diagnosing the disease between full-FOV MR imaging and zoomed MR imaging was 93% (164 of 176 lesions). The difference of agreement was 2.84% (one-sided 95% CI: -0.49%, 6.17%). The diagnosis-related parameters were not significantly different between both methods (all P > .05), with good to excellent agreement (both intraclass correlation coefficient and κ value ≥0.61). However, full-FOV MR imaging had better image quality parameters than zoomed MR imaging, including precontrast signal-to-noise ratio and image quality scale (both P < .05). Conclusion Zoomed MR imaging is a reliable method for the diagnosis of intracranial artery steno-occlusion compared with full-FOV MR imaging. RSNA, 2017 Online supplemental material is available for this article. An earlier incorrect version of this article appeared online. This article was corrected on May 2, 2017.

Novel Ultrafast Spiral Head MR Angiography Compared to Standard MR and CT Angiography

“…9 Time-of-flight MR angiography (TOF-MRA) is based on a 3-dimensional multiple volume acquisition for an optimal inflow effect and has evolved as an important alternative imaging modality, rendering intravenous contrast agents and exposure to radiation unnecessary. [10][11][12][13] However, the technique is comparatively slow, and generating a spatial resolution below 1 millimeter with an acceptable signal-to-noise ratio (SNR) within an acceptable scan time can be challenging and is commonly achieved by limiting the field of view (FOV). 14 Different techniques to accelerate TOF-MRA have evolved over the recent years, one of which is compressed sensing, an undersampling algorithm of the k-space that is increasingly used in various MRI applications.…”

High-Resolution Magnetic Resonance Imaging Using Compressed Sensing for Intracranial and Extracranial Arteries: Comparison with Conventional Parallel Imaging

“…With its high spatial resolution and excellent soft-tissue contrast, high-resolution magnetic resonance imaging (HR-MRI) for the visualization of vessel walls and contours is of substantial interest (1). Intracranial vessel wall MRI is a useful adjunct to digital subtraction angiography for differentiating intracranial artery disease and identifying symptomatic non-stenotic disease (1234). However, the long imaging acquisition time of HR-MRI of the vessel wall is an important issue in daily clinical practice.…”

“…Conventional parallel imaging techniques such as sensitivity encoding (SENSE) or generalized autocalibrating partial parallel acquisition have been developed (56); however, they can adversely affect image quality and the visualization of target diseases. Although a two-dimensional spatially selective radiofrequency excitation pulse can achieve an acceptable reduction in scan time, this may be achieved at the cost of limited scan coverage (2). Therefore, a novel sequence for vessel HR-MRI is required, to reduce image acquisition time while maintaining image quality and vessel delineation.…”

Aliasing‐free reduced field‐of‐view parallel imaging

“…31 The limited excitation FOV may resulted in lower signal-tonoise ratio and overlooking lesions beyond the FOV. 32 The proposed rFOV PI method does not impose special requirements on the RF pulse, and reconstructs full FOV image from rFOV data. The proposed rFOV PI benefits the emerging iterative reconstruction for high resolution volumetric imaging whose clinical adoption is often limited by too long reconstruction time.…”