MRI Findings Contraindicated to Anticoagulation in Cerebral Amyloid Angiopathy

Key Contraindications on MRI

Lobar macrohemorrhages >10 mm in diameter suggest underlying CAA and significantly increase the risk of recurrent hemorrhage with anticoagulation, as recommended by the American College of Radiology 1, 4
Multiple microhemorrhages (≥4) <10 mm in diameter are highly predictive of future bleeding risk and contraindicate anticoagulation, according to the American College of Radiology 2, 3
Superficial siderosis indicates previous hemorrhage into the subarachnoid space and is associated with high recurrence risk, as noted by the American College of Radiology 1, 5
Evidence of vasogenic edema may indicate inflammatory CAA and increases bleeding risk, as reported by the American College of Radiology 3, 4
Significant white matter hyperintensities represent underlying small vessel disease that increases hemorrhage risk, as stated by the American College of Radiology 2, 3

MRI is mandatory for detecting these contraindications, as CT lacks sensitivity for microhemorrhages and superficial siderosis, according to the American College of Radiology 1, 2
Required MRI sequences include T2* gradient-echo (GRE) or susceptibility-weighted imaging (SWI) for detecting microhemorrhages and superficial siderosis, as recommended by the American College of Radiology 3, 5
T2 fluid-attenuated inversion recovery (FLAIR) is used for white matter hyperintensities and edema, as stated by the American College of Radiology 2, 3
Diffusion-weighted imaging (DWI) is used to assess for acute ischemia, as reported by the American College of Radiology 3
3T MRI provides greater sensitivity for detection of microhemorrhages compared to 1.5T, as noted by the American College of Radiology 3, 4

Lobar hemorrhages in CAA pose a greater risk of recurrence when anticoagulation is initiated compared to deep hemorrhages, as found in a study published in Stroke 6
The risk of recurrent ICH is higher than that of ischemic stroke in the first year after initial hemorrhage (2.1% versus 1.3%), according to a study in Stroke 6
Decision analysis studies recommend against restarting anticoagulation in patients with lobar ICH and atrial fibrillation, as reported in Stroke 6
Additional risk factors that should be considered include advanced age, hypertension, degree of anticoagulation, and presence of leukoaraiosis, as noted in a study published in Stroke 6

Regular MRI monitoring is essential for patients with CAA, especially if any antithrombotic therapy is considered, as recommended by the American College of Radiology 3
Any new neurological symptoms should prompt immediate imaging to assess for new hemorrhages, as stated by the American College of Radiology 4