From the Guidelines
MRI is the preferred imaging modality over CT angiography to rule out embolic stroke in patients with infective endocarditis. This recommendation is based on the higher sensitivity of MRI with diffusion-weighted imaging (DWI) for detecting acute and subacute ischemic lesions, particularly small embolic infarcts that are common in infective endocarditis 1. For optimal results, a brain MRI protocol should include T1, T2, FLAIR, DWI, ADC mapping, and gradient echo or susceptibility-weighted sequences to detect both ischemic changes and potential hemorrhagic complications.
The use of MRI in this context is supported by its ability to detect cerebral infarcts in approximately 30-70% of endocarditis patients, even in those without neurological symptoms 1. In contrast, CT angiography is faster and more widely available but has lower sensitivity for small or early infarcts and exposes patients to ionizing radiation. CT angiography may be appropriate when MRI is contraindicated (such as in patients with certain implanted devices) or unavailable, or when there's a need to rapidly assess large vessel occlusions.
Key considerations in the management of patients with infective endocarditis include:
- The timing of imaging, which should be performed as soon as endocarditis is diagnosed, even in neurologically asymptomatic patients, as detection of silent embolic events may influence management decisions including anticoagulation strategies and timing of cardiac surgery 1.
- The importance of a thorough neurological evaluation and prognostication to guide further management in patients with neurological symptoms and deficits 1.
- The need for individualized decision-making regarding medical versus surgical therapy for intracranial mycotic aneurysms (ICMAs), taking into account the patient's age, underlying comorbid conditions, and the location of the ICMA 1.
Overall, the choice of imaging modality should be guided by the need to balance the risks and benefits of each option, with a focus on minimizing morbidity, mortality, and improving quality of life for patients with infective endocarditis.
From the Research
Imaging Modalities for Embolic Stroke in Infective Endocarditis
- The preferred imaging modality to rule out embolic stroke in patients with Infective Endocarditis is Magnetic Resonance Imaging (MRI) 2, 3, 4.
- MRI is more sensitive than Computed Tomography (CT) angiography in detecting brain lesions, including small ischemic lesions, microbleeds, and microabscesses 2.
- A study comparing CT and MRI found that MRI detected 137 lesions, while CT detected only 4 lesions, with 25 lesions detected by both techniques 2.
- MRI is also better at characterizing lesions, with contrast-enhanced scans identifying 68 enhancing lesions, mainly abscesses and microabscesses 2.
Characteristics of Brain Lesions in Infective Endocarditis
- Brain lesions in Infective Endocarditis can include acute ischemic lesions, intraparenchymal hemorrhages, cerebral microbleeds, subarachnoid hemorrhages, abscesses, microabscesses, and meningitis 2, 3.
- A study found that cortical branch infarction was the most common lesion, followed by numerous small embolic lesions, which typically lodged in the supratentorial gray-white junction 3.
- Brain hemorrhages, including subarachnoid hemorrhage, were also common, and some patients developed multiple frank parenchymal macroabscesses/cerebritis lesions 3.
Clinical Implications
- The presence of characteristic cranial MRI lesions, especially of multiple types, may prompt early diagnosis and treatment of Infective Endocarditis 3.
- Patients with Infective Endocarditis and cerebrovascular events tend to have higher morbidity and mortality, with increased requirement for intensive care unit care, mechanical ventilation, and surgical intervention 5.
- MRI can help identify patients at risk of embolic stroke and guide clinical management, including the use of anticoagulation therapy and surgical intervention 4, 5.