Improving diagnostic reliability of postoperative 3D TOF-MRA for cerebral aneurysms by optimizing the...

Three-dimensional time-of-flight magnetic resonance angiography (3D TOF-MRA) is widely used for non-invasive postoperative follow-up after cerebral aneurysm treatment. However, susceptibility artifacts from metallic clips or coils can cause apparent parent artery signal loss or missed detection of recanalization. This study aimed to evaluate whether optimization of the frequency-encoding direction improves diagnostic reliability compared with conventional 3D TOF-MRA.

Nine patients who underwent surgical clipping of cerebral aneurysms were included. For qualitative assessment, conventional MRA (c-MRA) and optimized MRA (o-MRA) were consecutively acquired in the same subjects. Visualization of the parent artery adjacent to the clip was independently evaluated by two experienced radiographers using a 5-point Likert scale. Statistical analysis was performed using the Wilcoxon signed-rank test and weighted kappa statistics. For quantitative assessment, three patients underwent o-MRA with the frequency-encoding direction set in the anterior-posterior (AP) and right-left (RL) directions. The diameter and extension direction of susceptibility artifacts were measured on the source images.

Qualitative assessment demonstrated significantly higher parent artery visualization scores with o-MRA than with c-MRA (p < 0.01). Interobserver agreement was excellent for both techniques (κ = 0.80 for c-MRA; κ = 0.89 for o-MRA). Quantitative analysis showed that susceptibility artifacts consistently elongated along the frequency-encoding direction.

Optimization of the frequency-encoding direction allows susceptibility artifacts to be controlled at the scan-planning stage, significantly improving diagnostic reliability in postoperative 3D TOF-MRA.

This technique requires no additional sequences, hardware, or scan time and can be immediately implemented as a practical scan-planning strategy in routine clinical imaging.