Correlation of apparent diffusion coefficient and computed tomography density in acute ischemic stroke.

Area of Science:

• Neurology
• Radiology
• Medical Imaging

Background:

• Acute ischemic stroke involves restricted molecular water diffusion (detectable by DWI MRI) and net water uptake (detectable by CT).
• Understanding the relationship between these imaging findings is crucial for early diagnosis and management.

Purpose of the Study:

• To compare the decrease in apparent diffusion coefficient (ADC) on diffusion-weighted MR imaging with CT density changes.
• To investigate the correlation between diffusion restriction and water uptake in acute stroke patients.

Main Methods:

• Twenty-five acute ischemic stroke patients underwent MR and CT imaging within hours of symptom onset.
• ADC and CT data were spatially registered, and regions of decreased ADC were overlaid on CT scans.
• Mean ADC and CT density values were compared between affected and unaffected hemispheres.

Main Results:

• A mean decrease in ADC (dADC) of 170+/-53x10(-6) mm2/s correlated with a decrease in CT density (dCT) of 1.3+/-0.7 HU.
• CT density showed a linear decrease (0.4 HU/h), while ADC decrease was rapid, nearing completion by 1.5 hours.
• A significant correlation (r=0.41, P=0.04) was found between ADC decrease and CT density decrease.

Conclusions:

• The severity of diffusion restriction correlates with net water uptake in acute ischemic stroke.
• Different time courses suggest a common underlying cause rather than direct causality.
• The rapid changes in ADC and slower, less pronounced CT density changes explain MRI's higher sensitivity in early ischemic stroke detection.