From the Guidelines
For stroke-like symptoms, immediately order a non-contrast CT scan of the brain to rule out hemorrhagic stroke, as recommended by the American Heart Association/American Stroke Association guidelines 1. This is the most critical initial step in diagnosing and managing stroke, as it helps distinguish between ischemic and hemorrhagic strokes. The guidelines emphasize the importance of brain imaging evaluation on arrival to the hospital, with non-contrast CT (NCCT) being the preferred initial imaging modality in most cases 1. Some key points to consider when ordering diagnostic tests for stroke-like symptoms include:
- The use of diffusion-weighted magnetic resonance imaging (DW-MRI) is not routinely recommended for all patients with acute ischemic stroke, but it may be useful in certain cases, such as those with puzzling clinical presentations or uncertain clinical stroke localization 1.
- The CT hyperdense MCA sign should not be used as a criterion to withhold IV alteplase from patients who otherwise qualify 1.
- Routine use of magnetic resonance imaging (MRI) to exclude cerebral microbleeds (CMBs) before administration of IV alteplase is not recommended 1. In addition to imaging studies, laboratory tests such as complete blood count, coagulation studies (PT/INR, PTT), comprehensive metabolic panel, cardiac enzymes, and blood glucose should be ordered, as well as an ECG to identify cardiac arrhythmias, particularly atrial fibrillation 1. If the patient presents within the treatment window, these diagnostics should be expedited, and additional tests such as carotid ultrasound, echocardiogram, and extended cardiac monitoring may be considered 1. Time is critical in stroke management, and the goal is to complete the evaluation and decide on treatment within 60 minutes of the patient's arrival in the emergency department 1.
From the Research
Imaging Options for Stroke-Like Symptoms
When a patient presents with stroke-like symptoms, it is essential to quickly and accurately diagnose the condition to provide appropriate treatment. The following imaging options can be considered:
- Computed Tomography (CT) scan: CT is the primary imaging modality used for selecting appropriate treatment in patients with acute stroke 2.
- Magnetic Resonance Imaging (MRI): MRI using diffusion techniques has a much higher sensitivity for acute lesions, but its implementation can be problematic due to initial resistance and technical problems 3.
- CT Angiography: CT angiography has become the operational standard for rapid accurate identification of intracranial large-vessel occlusion (LVO) 2.
- Multiphase CT Angiography: This technique can be used to estimate core infarct volume and distinguish patients likely to benefit from endovascular thrombectomy (EVT) from those unlikely to benefit 2.
- Perfusion CT: This technique can be used to estimate core infarct volume and distinguish patients likely to benefit from EVT from those unlikely to benefit 2.
- Diffusion-Weighted MRI: This technique can be used to identify the extension of potential viable brain tissue (penumbra) and of irreversible brain lesion (core) 4.
- MR Angiography: This technique can be used to determine the cause and mechanism of stroke, to define the extension of brain infarct, and to identify the arterial occlusion 4.
Treatment Selection
The choice of imaging modality depends on the patient's condition and the availability of equipment. The following factors should be considered when selecting a treatment:
- Time since onset of symptoms: Treatment options, such as intravenous tissue plasminogen activator, are time-sensitive 2, 5.
- Presence of large-vessel occlusion: CT angiography can be used to identify LVO and guide treatment decisions 2.
- Presence of hemorrhage: Imaging can be used to exclude hemorrhage and guide treatment decisions 2, 6.
- Extension of brain infarct: Imaging can be used to define the extension of brain infarct and guide treatment decisions 4.