Motion-insensitive carotid intraplaque hemorrhage imaging using 3D inversion recovery preparation stack of stars (IR-prep SOS) technique

Abstract

Purpose-Carotid artery imaging is important in the clinical management of patients at risk for stroke. Carotid intraplaque hemorrhage (IPH) presents an important diagnostic challenge. 3D magnetization prepared rapid acquisition gradient echo (MPRAGE) has been shown to accurately image carotid IPH; however, this sequence can be limited due to motion-and flow-related artifact. The purpose of this work was to develop and evaluate an improved 3D carotid MPRAGE sequence for IPH detection. We hypothesized that a radial-based k-space trajectory sequence such as "Stack of Stars" (SOS) incorporated with inversion recovery preparation would offer reduced motion sensitivity and more robust flow suppression by oversampling of central k-space.Materials and Methods-A total of 31 patients with carotid disease (62 carotid arteries) were imaged at 3T magnetic resonance imaging (MRI) with 3D IR-prep Cartesian and SOS sequences. Image quality was determined between SOS and Cartesian MPRAGE in 62 carotid arteries using t-tests and multivariable linear regression. Kappa analysis was used to determine interrater reliability.Results-In all, 25 among 62 carotid plaques had carotid IPH by consensus from the reviewers on SOS compared to 24 on Cartesian sequence. Image quality was significantly higher with SOS compared to Cartesian (mean 3.74 vs. 3.11, P < 0.001). SOS acquisition yielded sharper image features with less motion (19.4% vs. 45.2%, P < 0.002) and flow artifact (27.4% vs. 41.9%, P < 0.089). There was also excellent interrater reliability with SOS (kappa = 0.89), higher than that of Cartesian (kappa = 0.84). *Address reprint requests to: S.-E.K., Utah Center for Advanced Imaging Research, 729 Arapeen Dr., Salt Lake City, UT, 84108. sekim@ucair.med.utah.edu. The basic premise of the MPRAGE sequence is that tissue with long T 1 relaxation times (blood and muscle) can be differentiated from tissue with short T 1 relaxation times (hemorrhage and fat) using nonselective inversion recovery preparation. Hemorrhage can be further delineated from fat by the addition of fat saturation to the sequence. The inversion time is selected to minimize the signal from flowing blood and other tissues to allow for maximum hemorrhage contrast. HHS Public AccessAlthough promising, MPRAGE accuracy can be limited by patient motion and flow-related artifact. Higher-resolution 3D MPRAGE requires long scan times to compensate for reduced signal-to-noise ratio (SNR), increasing the likelihood of motion artifacts and nondiagnostic studies. A previous study found that over one-third of MPRAGE exams exhibit motion artifacts. 11 Elimination of motion artifact will improve IPH detection and better assess IPH location relative to surface disruption. A motion-robust 3D radial and Cartesian hybrid sequence such as 3D "Stack of Stars" (SOS) has been used to acquire volumetric k-space data, where radial sampling is performed in-plane (along ky and kx) and Cartesian sampling is used along the slice dimension (kz). 12 Compared with conventional Cartesian sampl...

Magnetization‐prepared GRASP MRI for rapid 3D T1 mapping and fat/water‐separated T1 mapping

“…27 However, to date, the use of stack-of-stars imaging is primarily limited to steady-state acquisitions and its combination with magnetization-prepared data acquisition has been limited to only a few prior studies. Kim et al applied an inversion recovery (IR)-prepared stack-of-stars sequence for motion-insensitive carotid imaging, 28 but it is restricted to qualitative imaging for improving image contrast. A similar implementation has also been tested recently for motioninsensitive brain imaging.…”

Surveillance of abdominal aortic aneurysm using accelerated 3D non-contrast black-blood cardiovascular magnetic resonance with compressed sensing (CS-DANTE-SPACE)

“…However, the abdominal motion surrounding the AAA, especially in phase-encoding directions can still generate motion artifacts that propagate through the region of the AAA. One possible solution to further reduce motion artifact is to use radial k-space sampling (for example, stack of stars) together with gradient echo based sequences, which is inherently motion-robust and shows high promise in body imaging [19] and black-blood carotid vessel wall imaging [20]. The combination of compressed sensing and radial acquisition [19] can also be explored in future studies to reduce both the scan time and motion artifacts for AAA imaging.…”

Differentiation of symptomatic and asymptomatic carotid intraplaque hemorrhage using 3D high‐resolution diffusion‐weighted stack of stars imaging

“…3D DW-SOS acquisitions were centered approximately at the bifurcation of healthy subjects or at the plaque and IPH detected on 3D MPRAGE images. 47 The DW imaging parameters were: receiver bandwidth = 490 Hz/pixel, FOV = 152 x 152 mm 2 , base resolution = 256, 2 mm slice thickness, TE/TR = 2.05/10.0 ms, and 32 slices/slab. The in-plane spatial resolution for a typical data acquisition was 0.6 x 0.6 mm 2 .…”

“…Carotid IPH was defined by MPRAGE-positive plaque with ≥2-fold signal compared with sternocleidomastoid muscle, which corresponds well to carotid. 47,51 2.7 | ADC measurements and statistical analysis ADC maps were calculated and displayed using algorithms developed in Matlab. 3D T1w and MPRAGE were reformatted and manually aligned axially with ADC maps based on the flow divider location.…”