Spiral T1 Spin-Echo for Routine Postcontrast Brain MRI Exams: A Multicenter Multireader Clinical Evaluation

Abstract

BACKGROUND AND PURPOSE: Spiral MR imaging has several advantages compared with Cartesian MR imaging that can be leveraged for added clinical value. A multicenter multireader study was designed to compare spiral with standard-of-care Cartesian postcontrast structural brain MR imaging on the basis of relative performance in 10 metrics of image quality, artifact prevalence, and diagnostic benefit. MATERIALS AND METHODS: Seven clinical sites acquired 88 total subjects. For each subject, sites acquired 2 postcontrast MR imaging scans: a spiral 2D T1 spin-echo, and 1 of 4 routine Cartesian 2D T1 spin-echo/TSE scans (fully sampled spin-echo at 3T, 1.5T, partial Fourier, TSE). The spiral acquisition matched the Cartesian scan for scan time, geometry, and contrast. Nine neuroradiologists independently reviewed each subject, with the matching pair of spiral and Cartesian scans compared side-by-side, and scored on 10 image-quality metrics (5-point Likert scale) focused on intracranial assessment. The Wilcoxon signed rank test evaluated relative performance of spiral versus Cartesian, while the Kruskal-Wallis test assessed interprotocol differences. RESULTS: Spiral was superior to Cartesian in 7 of 10 metrics (flow artifact mitigation, SNR, GM/WM contrast, image sharpness, lesion conspicuity, preference for diagnosing abnormal enhancement, and overall intracranial image quality), comparable in 1 of 10 metrics (motion artifacts), and inferior in 2 of 10 metrics (susceptibility artifacts, overall extracranial image quality) related to magnetic susceptibility (P , .05). Interprotocol comparison confirmed relatively higher SNR and GM/WM contrast for partial Fourier and TSE protocol groups, respectively (P , .05). CONCLUSIONS: Spiral 2D T1 spin-echo for routine structural brain MR imaging is feasible in the clinic with conventional scanners and was preferred by neuroradiologists for overall postcontrast intracranial evaluation. ABBREVIATIONS: Cart 4 Cartesian; IQ 4 image quality; NA 4 not applicable; SE 4 spin-echo; TSE 4 turbo spin-echo S tructural T1-weighted sequences are a fundamental component of routine postcontrast brain MR imaging examinations. These contrast-enhanced images are used for the diagnostic detection and evaluation of abnormal enhancement, including tumors, infections, and inflammatory diseases. Cartesian 2D T1 spin-echo (SE) is widely used as the standard-of-care, though it is relatively slow due to its single phase-encode per shot k-space coverage, and is not compatible with parallel imaging due to strong free-induction decay artifacts from the refocusing radiofrequency pulse. Two routine speed-up options include Cartesian 2D T1-SE with partial-Fourier k-space coverage, but at the cost of reduced SNR; alternatively, Cartesian 2D T1 turbo spin-echo

Contrast-Enhanced T1-Weighted Head and Neck MRI: Prospective Intraindividual Image Quality Comparison of Spiral GRE, Cartesian GRE, and Cartesian TSE Sequences

“…Further, spiral trajectories exhibit inherently reduced gradient moments, central k-space oversampling, and no dedicated phase-encoding direction. These traits render spiral sequences more robust in terms of several artifacts [6,7,12,13,16,17]. The advantages of spiral MRI were demonstrated in clinical pilot studies for brain and spine imaging [8][9][10][11][12][13].…”

“…The spiral sequence used a stack of spirals scheme with an in-plane spiral-out readout. For the spiral sequence, blurring due to offresonance was corrected during reconstruction based on a magnetic field map (B0 map) acquired before the spiral scan [6,7,12].…”

“…Sequences with non-Cartesian k-space sampling such as spiral sequences have been proposed as an alternative to Cartesian sequences for improved imaging in anatomic regions associated with high degrees of artifact. Spiral sequences offer high k-space sampling efficiency and central k-space oversampling, thus enabling artifact-robust imaging at even shorter scan times than for conventional T1W sequences [6,7]. Spiral sequences have previously shown promise for anatomic and functional imaging of various regions [6][7][8][9][10][11][12][13][14].…”

“…Spiral sequences offer high k-space sampling efficiency and central k-space oversampling, thus enabling artifact-robust imaging at even shorter scan times than for conventional T1W sequences [6,7]. Spiral sequences have previously shown promise for anatomic and functional imaging of various regions [6][7][8][9][10][11][12][13][14]. However, to our knowledge, the utility of spiral sequences has not been systematically explored for clinical head and neck MRI.…”

MaxGIRF: Image reconstruction incorporating concomitant field and gradient impulse response function effects

“…Image quality from MRI that uses non‐Cartesian sampling, particularly spirals, has improved continuously over the past 30 years. Current state‐of‐the‐art spiral MRI provides quality that is comparable to its 2D/3D Cartesian counterparts, and is appropriate for clinical use 1,2 . Spiral acquisitions are attractive because they provide high scan and SNR efficiency, robustness to motion artifacts, and are advantageous for fast imaging applications such as MR fingerprinting 3,4 and cardiac imaging 5 …”