From the Guidelines
The presence of microhemorrhages on brain MRI does not necessarily contraindicate the use of thrombolytic agents, especially if the number of microhemorrhages is small (<5) 1. When considering the management of patients with microhemorrhages on MRI, it's essential to weigh the risks and benefits of thrombolytic therapy. The evidence suggests that while microhemorrhages may predict recurrent disabling and fatal strokes, there is no statistically significant increase in the risk of symptomatic intracranial hemorrhage (ICH) when patients with a small number of microhemorrhages are treated with intravenous thrombolysis 1. Key points to consider in the management of microhemorrhages include:
- The number and location of microhemorrhages, as well as the patient's clinical context, are crucial in determining the significance of these findings
- Controlling blood pressure is essential, particularly in patients with numerous microhemorrhages, aiming for levels below 130/80 mmHg
- Regular follow-up with a neurologist is recommended, and patients with microhemorrhages should be carefully evaluated before starting blood thinners
- Microhemorrhages are important markers of underlying cerebrovascular disease and may indicate an increased risk for future strokes or cognitive impairment, particularly when they occur in large numbers or specific patterns In terms of imaging, MRI, particularly T2* GRE and SWI sequences, is highly sensitive to microhemorrhages within the brain 1. However, the association between the number and volume of microhemorrhages and injury severity or outcomes remains inconclusive 1. In clinical practice, the decision to use thrombolytic agents in patients with microhemorrhages on MRI should be made on a case-by-case basis, taking into account the individual patient's risk factors and clinical context 1.
From the Research
Microhemorrhage on MRI of Brain
- Microhemorrhages, also referred to as cerebral microbleeds (CMBs), appear on magnetic resonance (MR) images as hypointense foci, notably at T2*-weighted or susceptibility-weighted (SW) imaging 2.
- The imaging appearance of CMBs is mainly due to changes in local magnetic susceptibility and reflects the pathologic iron accumulation, most often in perivascular macrophages, because of vasculopathy 2.
- CMBs can be caused by various conditions, including cerebral amyloid angiopathy, chronic systemic hypertension, diffuse axonal injury, cerebral embolism, and vasculitis 3.
Detection and Diagnosis
- CMBs are detected with increasing frequency due to the more widespread use of high magnetic field strength and newer dedicated MR imaging techniques such as three-dimensional gradient-echo T2*-weighted and SW imaging 2.
- The detection rate of CMBs increases with field strength, with the use of three-dimensional sequences, and with postprocessing methods that use local perturbations of the MR phase to enhance T2* contrast 2.
- False-positive "mimics" of CMBs can occur, including microdissections, microaneurysms, and microcalcifications, which can be differentiated by using phase images 2.
Clinical Significance
- The presence of CMBs in patients with stroke is increasingly recognized as a marker of worse outcome 2.
- CMBs may be used to estimate the balance between hemorrhagic and ischemic risks in patients with cerebrovascular diseases 4.
- The presence of CMBs on MRI and the dichotomized cutoff of ≥5 CMBs might identify subgroups of ischemic stroke patients with atrial fibrillation with high intracerebral hemorrhage risk 5.
- However, in patients with mild traumatic brain injury, microhemorrhagic lesions were not related to early complaints 6.