Acceleration of pCASL-Based Cerebral 4D MR Angiography Using Compressed SENSE: A Comparison With SENSE

ObjectivesThe objectives of this study were to accelerate the non-contrast-enhanced four-dimensional magnetic resonance angiography (4D MRA) based on pseudocontinuous arterial spin labeling combined with the Keyhole and View-sharing (4D-PACK) procedure using the Compressed SENSE (C-SENSE) and to improve intracranial vasculopathy evaluations for clinical purposes. Methods4D-PACK acquisition with different C-SENSE and SENSE acceleration factors was performed on 29 healthy volunteers and six patients by means of a 3.0 T MR system. Two radiologists used a 4-grade scale to qualitatively assess the vessel visualization of the middle cerebral artery (MCA) and used a 5-grade scale to qualitatively examine the image quality of 4D-PACK axial source images. Interobserver agreement was assessed by determining the weighted kappa statistic. The contrast-to-noise ratio (CNR) and arterial transmit time (ATT) were calculated in four segments of the MCA. The repeated measures one-way ANOVA for CNR and the Friedman test for source images and vessel visualization were used to analyse the differences in five sequences. Results(1) At the M4 segment, C-SENSE5 acquisition (scores, 2.72 +/- 0.53) and C-SENSE6.5 (scores, 2.55 +/- 0.57) provided similar vessel visualization compared with SENSE4.5 (scores, 2.72 +/- 0.46); however, C-SENSE8 (scores, 1.79 +/- 0.49) and C-SENSE10 (scores, 1.52 +/- 0.51) had lower scores (P < 0.050). (2) The source image quality of C-SENSE5 (scores, 4.55 +/- 0.51), C-SENSE6.5 (scores, 4.03 +/- 0.33), and C-SENSE8 (scores, 3.48 +/- 0.51) acquisition was higher than that of SENSE4.5 (scores, 3.07 +/- 0.26) (P < 0.001). (3) CNRs of different MCA segments for C-SENSE5 and C-SENSE6.5 acquisitions were not significantly different compared with that of SENSE4.5 acquisition. However, the CNRs were significantly lower for C-SENSE8 (M1: 45.85 +/- 13.91, M2: 27.08 +/- 9.92, M4: 7.93 +/- 4.49) and C-SENSE10 (M1: 37.94 +/- 9.92, M2: 23.51 +/- 9.0, M4: 6.78 +/- 4.12) than for SENSE4.5 (M1: 55.49 +/- 13.39, M2: 36.94 +/- 11.02, M4: 10.18 +/- 5.15) in each corresponding segment (P < 0.050). ATTs in all MCA segments within different accelerating C-SENSE factors were obviously correlated with SENSE4.5. ConclusionC-SENSE6.5 acquisition could be used to evaluate both the intracranial macrovascular and distal arteries, which could reduce the acquisition time by 18% (5 min 5 s) compared with SENSE4.5. Moreover, C-SENSE8 acquisition (37% acceleration, 3 min 54 s) could be used for routine screening and clinical diagnosis of intracranial macrovascular disease with balanced image quality.

Automated summary

The study aimed to accelerate non-contrast-enhanced 4D MRA for intracranial vasculopathy evaluations by using C-SENSE and to improve image quality. Results showed that C-SENSE6.5 could be used for evaluating both intracranial macrovascular and distal arteries, reducing acquisition time by 18%, while C-SENSE8 could be used for routine screening and clinical diagnosis with balanced image quality.