Detection of inflammation in abdominal aortic aneurysm with reduced field-of-view and low-b-value diffusion-weighted imaging

Objectives: To evaluate the performance of diffusion-weighted imaging (DWI) with an optimal b-value and field-of-view in identifying wall inflammation in abdominal aortic aneurysm (AAA) by comparing it to delayed enhancement T1-weighted imaging (DEI).

Methods: Twenty-five males with AAA were prospectively enrolled and underwent fat-suppressed T1-weighted dark-blood imaging (T1WI), full field-of-view (f-FOV) and reduced field-of-view (r-FOV) DWI (b values = 0, 100, 400 and 800 s/mm²), and DEI. Corresponding images on f-FOV, r-FOV DWI and DEI at the same level were evaluated qualitatively and quantitatively using the paired t-test and Wilcoxon signed-rank test. The agreement in detecting wall inflammation between DWI and DEI sequences was analyzed using weighted kappa statistics.

Results: For both r-FOV and f-FOV DWI, the scores of delineation of aneurysm wall and lesion conspicuity, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were highest on DWI₁₀₀ (Ps < 0.05). The scores of delineation of aneurysm wall, geometric distortion, lesion conspicuity, and SNR, CNR were significantly higher on r-FOV DWI than those on f-FOV DWI (Ps < 0.05). r-FOV DWI₁₀₀ showed comparable performance to DEI in detecting wall inflammation (κ = 0.715), with superior blood suppression and higher SNR and CNR (Ps < 0.05).

Conclusions: DWI with r-FOV and low b-value could be a promising alternative to DEI in identifying wall inflammation in AAA.