Silent MR angiography in the detection of intracranial aneurysm: a feasibility study

Objective To evaluate image quality and diagnostic performance of silent MR angiography (MRA) and discuss the feasibility of silent MRA in diagnosing intracranial aneurysms. Methods Twenty seven patients suspected with cerebrovascular disorders and 30 intracranial aneurysms in Northern Jiangsu People's Hospital, were enrolled prospectively in this study from December 2015 to December 2018. Silent and time of flight (TOF) MRA were performed on the same day prior to CTA examination. The corresponding MRA images were independently and blindly evaluated by two experienced neuroradiologists in the aspects of signal homogeneity, lesion conspicuity, venous signal/artifact and diagnostic confidence (4-point scale). The aneurysms were divided into tiny (≤ 3 mm) and non-tinyaneurysm groups(> 3 mm) according to the measured diameters of aneurysms. The differences in image quality ratings between silent MRA and TOF MRA were analyzed using Wilcoxon signed rank tests. Intra-class correlation coefficients (ICC) were used to test the consistency of measurements between MRAs (silent MRA, TOF MRA) and CTA. Results CTA revealed 32 intracranial aneurysms. For silent MRA and TOF MRA, the scores of signal homogeneity were 3.38±0.49 and 3.00±0.62, andthe scores of venous signal/artifact were 3.77±0.42 and 2.65±0.48.Significant differences were found between the two MRAs in these aspects (Z=-2.21, P=0.02; Z=-5.69, P=0.01). The scores of lesion conspicuity were 3.19±0.56 and 3.15±0.46, and the scores of diagnostic confidence were 3.27±0.44 and 3.12±0.51.There were no significant differences found in these aspects (P>0.05).The ICC coefficient was excellentfor silent MRA (0.94, 95%CI 0.82- 0.98)and was good for TOF MRA (0.72, 95%CI 0.30-0.91) in tiny aneurysm group. The ICC coefficient was excellent (silent MRA, 0.98, 95%CI 0.95-0.99; TOF MRA, 0.95, 95%CI 0.87-0.98) for both MRA in non-tiny aneurysm group. Conclusions Compared with TOF MRA, silent MRA could achieve higher image quality and higher diagnostic confidence, and higher consistency with CTA. Silent MRA can be a promising non-contrast-enhanced alternative MRA technique in clinical setting. Key words: Magnetic resonance imaging; Intracranial aneurysm; Diagnosis, differential; Comparative study