Effect of thin-section diffusion-weighted MR imaging on stroke diagnosis

Area of Science:

• Neuroradiology
• Medical Imaging

Background:

• Diffusion-weighted (DW) imaging, crucial for diagnosing acute cerebral ischemia, faces limitations in spatial resolution, particularly in the z-direction.
• Conventional DW imaging uses a 5-mm section thickness with a 1-mm intersection gap, potentially hindering the visualization of small infarcts.

Purpose of the Study:

• To evaluate if decreasing DW imaging section thickness to 3 mm improves the depiction of small infarcts.
• To determine the impact of thin-section DW imaging on the accuracy of stroke diagnosis.

Main Methods:

• A comparative study involving 49 patients with acute cerebral ischemia symptoms, analyzing both conventional (5-mm) and thin-section (3-mm) DW imaging data.
• Two radiologists independently diagnosed stroke subtypes using the Trial of Org 10172 in Acute Stroke Treatment (TOAST) method, blinded to clinical information.
• Quantitative analysis of lesion conspicuity using contrast-to-noise ratios (CNRs), calculating the relative CNR (rCNR) between thin-section and conventional imaging.

Main Results:

• Stroke diagnosis accuracy improved significantly with thin-section DW imaging: from 78% to 100% for an experienced neuroradiologist and from 71% to 94% for a radiology resident.
• Lesion conspicuity was markedly enhanced on thin-section DW imaging, with an average rCNR of 1.47 ± 0.63.
• A notable improvement in conspicuity was observed for supratentorial lesions (rCNR = 1.51 ± 0.63).

Conclusions:

• Thin-section DW imaging (3 mm) offers superior lesion conspicuity compared to conventional 5-mm thick slices.
• This technique leads to more precise and accurate stroke diagnosis, particularly for subtle infarcts.