The added value of b0-DWI analysis in the diagnosis of cavitating lacunes when T2-weighted spin-echo is unavailable

Purpose

Silent brain infarcts, sometimes appearing as incidental lacunes in patients with unknown history of vascular event, are linked to dementia, gait disturbances and depression. We observed that some cavitating lacunes were only visible on b0-diffusion-weighted-imaging (b0-DWI: T2-weighted without diffusion gradients) when T2-weighted-spin-echo (T2-SE) was unavailable. We aimed to evaluate the additional value of b0-DWI in detecting cavitating lacunes.

Methods

We retrospectively included patients aged ≥ 65 years who underwent brain MRI (1.5 T or 3 T) for various indications, with FLAIR (Fluid Attenuated Inversion Recovery) and b0-DWI, without T2-SE. Patients with multiple sclerosis, lacking b0-DWI or with low-quality MRI were excluded. Vascular risk factors, white matter lesions (Fazekas scale) and mention of lacune in the radiology report were inquired. Two radiologists independently analyzed all b0-DWI sequences, followed by FLAIR.

Results

Among 306 subjects, at least one lacune was observed in 149 (48.7 %): 54 (36.2 %) supratentorial, 32 (21.5 %) infratentorial and 63 (42.3 %) both. Of these, 119 (79.9 %) had vascular risk factors and 135 (90.6 %) had white matter lesions. 33 (10.8 %) were exclusively detected on b0-DWI (b0-DWI-lacunes), of which 5 (1.6 %) without vascular factor, and 20 (6.5 %) were unmentioned in the report. Among b0-DWI-lacunes, 15 (45.5 %) were supratentorial, 9 (27.3 %) infratentorial and 9 (27.3 %) both, with 28 (84.8 %) associated with white matter lesions. Inter-rater reliability for b0-DWI-lacunes diagnosis was good (95.6 % agreement, kappa = 0.717, CI_95% [0.568–0.869]).

Conclusion

In our study, 10.8% b0-DWI-lacunes were not visible on FLAIR, and 6.5% were unmentioned in the neuroradiology report. Examining FLAIR alongside b0-DWI improves diagnostic performance for cavitating lacune detection and contributes to vascular prevention.