Can Hybrid Arterial Spin Labeling-Tagged Zero-Echo-Time Magnetic Resonance Angiography Be an Effective Candidate in the Evaluation of Intracranial Artery Diseases? A Clinical Feasibility Study

Background Flow related artifacts in continuous arterial spin labeling (cASL) zero-echo-time (ZTE) magnetic resonance angiography (MRA) could influence the vasculature visualization. Purpose To investigate the clinical feasibility for the intracranial artery diseases assessment by utilizing hybrid ASL-ZTE-MRA (hASL-ZTE-MRA). Study Type Prospective, technical development. Population Sixty-seven subjects with known/suspected cerebrovascular diseases. Field Strength/Sequence Gradient echo based cASL-/hASL- ZTE-MRA at 3.0 T. Assessment Subjective/objective evaluation for sound-levels. Image quality (IQ), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were analyzed within artery segments. Stenotic grading, aneurysm measurement, and signal intensity of lesions were further analyzed. Statistical Tests Kolmogorov-Smirnov test for data normality check. Between two MRAs: Wilcoxon signed-rank test for sound experience/IQ ratings analysis; Paired t test for SNR/CNR comparison. One-way analysis of variance for sound intensity comparison. For stenosis grading/aneurysm measurement: Kendall's W test/intraclass correlation coefficient (ICC) for interobserver agreement test within each modality, weighted kappa statistics/ICC for intermodality agreement test between each MRA and computed tomography angiography. Results Sound-level perception/intensity was similar (P = 0.86, P = 0.55) between MRAs. The mean IQ score for hASL-ZTE-MRA was on diagnostic scale and slightly higher (P < 0.05) than that of cASL-ZTE-MRA. hASL-ZTE-MRA provided higher (P < 0.05) SNR/CNR than that of cASL-ZTE-MRA. Signal uniformity was improved on hASL-ZTE-MRA, particularly among the anterior circulation (P < 0.05). Comparing to cASL-ZTE-MRA, on hASL-ZTE-MRA, stenotic lesions were accurately assessed; flow in the stent or aneurysm remnant was better depicted (P < 0.05); AVM nidus was preferred with increased SNR (P < 0.05). No significant differences for the aneurysm measurement were found between MRAs (P = 0.95), in addition to the slightly higher SNR (P < 0.05) on hASL-ZTE-MRA. Data Conclusion Comparing to cASL-ZTE-MRA, hASL-ZTE-MRA is robust and feasible for the evaluation of intracranial artery diseases with diagnostic IQ, improved vessel contrast, and better signal heterogeneity. Level of Evidence 2 Technical Efficacy 2

Automated summary

The study investigated the feasibility of using hybrid ASL-ZTE-MRA technology for assessing intracranial artery diseases, showing improved image quality, signal-to-noise ratio, and vessel contrast. The hASL-ZTE-MRA technique allowed for accurate assessment of stenotic lesions, better depiction of flow in stents or aneurysm remnants, and increased signal-to-noise ratio for arteriovenous malformation nidus.