Delayed Lesions on Diffusion-Weighted Imaging in Initially Lesion-Negative Stroke Patients

Area of Science:

• Neurology
• Radiology
• Stroke Medicine

Background:

• Diffusion-weighted imaging (DWI) is crucial for acute stroke detection.
• Some stroke patients initially show no DWI lesions but develop them on follow-up MRI.
• Understanding this phenomenon is key for accurate diagnosis and risk assessment.

Purpose of the Study:

• To determine the prevalence of positive DWI conversion in initially DWI-negative stroke patients.
• To identify clinical factors associated with this delayed lesion appearance.
• To assess the association between DWI conversion and recurrent stroke risk.

Main Methods:

• Retrospective, observational, single-center study of 5,271 stroke/TIA patients (2010-2017).
• Included patients without initial DWI lesions who underwent follow-up DWI.
• Used Cox regression to analyze recurrent stroke risk and logistic regression for factors associated with positive conversion.

Main Results:

• 13.2% (694/5271) were initially DWI-negative; 22.5% of these showed positive conversion on follow-up.
• Positive conversion significantly increased recurrent stroke risk (aHR=3.12).
• Factors associated with conversion included early neurologic deterioration, atrial fibrillation, smoking, pre-stroke dependency, hemiparesis, longer symptom duration, high cholesterol, NIHSS score, and high systolic blood pressure.

Conclusions:

• Positive DWI conversion in stroke/TIA patients is linked to a higher risk of subsequent strokes.
• Identifying DWI-negative stroke patients with specific risk factors may warrant follow-up MRI for definitive diagnosis.
• This highlights the importance of serial imaging in select stroke cases.