Cerebral microbleeds on MR imaging: comparison between 1.5 and 7T

Area of Science:

• Neuroimaging
• Radiology
• Vascular Neurology

Background:

• Detection of cerebral microbleeds varies significantly across studies due to differing MRI protocols.
• Standard 1.5T MRI protocols may limit the sensitivity for identifying microbleeds.

Purpose of the Study:

• To compare the visualization and detection of cerebral microbleeds using 3D T2*-weighted imaging at 1.5 Tesla (T) versus 3D dual-echo T2*-weighted imaging at 7T.
• To assess the reliability of microbleed detection at both magnetic field strengths.

Main Methods:

• Thirty-four patients with atherosclerotic disease underwent both 1.5T 3D T2*-weighted and 7T 3D dual-echo T2*-weighted MRI.
• Definite microbleeds were identified, and their presence and number were recorded.
• Inter- and intraobserver reliability were evaluated using the Intraclass Correlation Coefficient (ICC).

Main Results:

• 7T MRI detected microbleeds in significantly more patients (50%) compared to 1.5T MRI (21%) (P = .001).
• The number of microbleeds identified was also higher at 7T (median 0.5) than at 1.5T (median 0.0) (P = .002).
• Interobserver reliability was higher at 7T (ICC = 0.61) than at 1.5T (ICC = 0.50), with excellent intraobserver reliability at both (0.94 for 7T, 0.59 for 1.5T).

Conclusions:

• 3D dual-echo T2*-weighted imaging at 7T provides superior detection of cerebral microbleeds compared to 1.5T imaging.
• The 7T protocol demonstrates enhanced reliability for identifying microbleeds, crucial for understanding cerebrovascular disease.