Prog Med Phys.  2022 Dec;33(4):88-100. 10.14316/pmp.2022.33.4.88.

Contribution of Microbleeds on Microvascular Magnetic Resonance Imaging Signal

• Yoo CH
• Goh J
• Jahng GH

• KMID: 2537876
• DOI: http://doi.org/10.14316/pmp.2022.33.4.88

Abstract

Purpose
Cerebral microbleeds are more susceptible than surrounding tissues and have been associated with a variety of neurological and neurodegenerative disorders that are indicative of an underlying vascular pathology. We investigated relaxivity changes and microvascular indices in the presence of microbleeds in an imaging voxel by evaluating those before and after contrast agent injection.
Methods
Monte Carlo simulations were run with a variety of conditions, including different magnetic field strengths (B ₀ ), different echo times, and different contrast agents. ΔR2^* and ΔR2 and microvascular indices were calculated with varying microvascular vessel sizes and microbleed loads.
Results
As B ₀ and the concentration of microbleeds increased, ΔR2^* and ΔR2 increased. ΔR2^* increased, but ΔR2 decreased slightly as the vessel radius increased. When the vessel radius was increased, the vessel size index (VSI) and mean vessel diameter (mVD) increased, and all other microvascular indices except mean vessel density (Q) increased when the concentration of microbleeds was increased.
Conclusions
Because patients with neurodegenerative diseases often have microbleeds in their brains and VSI and mVD increase with increasing microbleeds, microbleeds can be altered microvascular signals in a voxel in the brain of a neurodegenerative disease at 3T magnetic resonance imaging.

Keyword

Brain; Gadolinium-chelated; Microbleed; Microvascular; Magnetic resonance imaging