A comparison of four dimensional time-resolved with keyhole and three dimensional time-of-flight MR angiography for the evaluation of cerebral aneurysms / 中华放射学杂志

ABSTRACT

Objective To evaluate the accuracy and reliability of 4D time-resolved MRA with keyhole (4D-TRAK) for the detection and characterization of cerebral aneurysms ( CAs),with a comparison of 3D time-of-flight MRA (3D-TOF-MRA).Methods3D-TOF-MRA,4D-TRAK and 3D-DSA were performed sequentially in 52 patients with suspected CAs.4D-TRAK was acquired using a combination of sensitivity encoding (SENSE) and contrast-enhanced (CE) timing robust angiography ( CENTRA ) k-space sampling techniques at a contrast dose of 10 ml at 3 T scanner. Accuracy,sensitivity,specificity of 4D-TRAK and 3D-TOF-MRA were calculated and compared for the detection of CAs on patient-based and aneurysm-based evaluation using 3D-DSA as a reference. Wilcoxon signed rank test were used. Results The overall image quality of 4D-TRAK was appropriate for the diagnostic purpose,but yet not comparable with that of 3D-TOF-MRA.In 52 patients with suspected GAs,58 CAs were confirmed on 3D-DSA finally.Fifty-one (with 2 false-positives and 9 false-negatives) and 58 (with 1 false-positive and 1 false-negative)CAs were visualized on 4D-TRAK and 3D-TOF-MRA,respectively.Accuracy,sensitivity and specificity on patient-based evaluation of 4D-TRAK and 3D-TOF-MRA were 92.31％ ( 48/52 ),93.33％ ( 42/45 ),85.71 ％ (6/7) and 98.08％ ( 51/52 ),100.00％ ( 45/45 ),85.71％ ( 6/7 ),respectively,and 74.07％(20/27),75.00％ ( 18/24),66.67％ (2/3) and 96.30％ (26/27),95.83％ (26/27),100.00％ (3/3)on aneurysm-based evaluation in patients with multiple CAs,respectively.Subgroup analysis revealed that for 19 very small CAs ( maximal diameter ＜3 mm,measured on 3D-DSA),9 were missed on 4D-TRAK and 1 on 3D-TOF-MRA( Z =- 2.464,P ＜ O.01 ). However,for 39 CAs with maximal diameter more than 3 mm,there was no significantly difference in the diagnostic accuracy (39 on 4D-TRAK vs.39 on 3D-TOFMRA) (Z =0.000,P ＞0.05).In 4 large CAs with maximal diameter more than 10 mm,4D-TRAK provided a better characterization of morphology than 3D-TOF-MRA.Conclusions 4D-TRAK with a combination of SENSE and CENTRA at 3 T shows potential value in the diagnosis of cerebral aneurysms.However,due to the compromise in spatial resolution and vascular edge artifacts,it does not yet have a diagnostic accuracy of CAs comparable with 3D-TOF-MRA.TRAK imaging can be of great help in patients with large-giant CAs to characterize the morphology of CAs and to diminish the risk of NSF in patients with renal impairment by using a lower-dose contrast.