Table 2. Subgroup assessment of average score of image quality on silent MRA and TOF MRA.

Subgroup grading criteria	Silent MRA	TOF MRA	P value
Total (n=85)	2.83±0.42	2.46±0.66	<0.001*
New hemorrhage
+ (n=22)	2.77±0.35	2.16±0.68	<0.001*
– (n=63)	2.85±0.36	2.55±0.46	<0.001*
P value	0.542	0.001*
Embolization
+ (n=35)	2.81±0.41	2.39±0.57	<0.001*
– (n=50)	2.85±0.32	2.50±0.52	<0.001*
P value	0.606	0.832
Nidus size
<3 cm (n=26)	2.74±0.53	2.06±0.64	<0.001*
3–6 cm (n=50)	2.92±0.21	2.65±0.37	<0.001*
>6 cm (n=9)	2.85±0.34	2.37±0.56	0.021*
P value	0.109	<0.001*
Compactness
+ (n=70)	2.86±0.35	2.50±0.51	<0. 001*
– (n=15)	2.71±0.38	2.29±0.65	0.042*
P value	0.714	0.037*

Data are presented as mean ± SD. *, statistical significance. MRA, magnetic resonance angiography; TOF MRA, time-of-flight magnetic resonance angiography; SD, standard deviation.