When a patient is first referred for a work-up, our interdisciplinary team will meet to discuss the precise role of specific imaging options to help evaluate the patient’s diagnosis and management plan. Possible tests include:
- Compute Tomography Angiography (CTA): This is a “CAT” scan, or non-invasive, XRAY-based scan where dye is injected into the veins to visualize the arteries and veins of the brain and scalp.
- Diagnostic Cerebral Angiogram (Angiogram): This is an invasive study performed via accessing the radial or femoral artery with catheters and wires, and injecting dye into the blood vessels of the head and neck. This is performed by a neuro-interventionalist and enables us to see the difference between arteries and veins with alternative sources of blood flow to specific parts of the brain (termed “collaterals”). This helps us decide (1) whether surgery is helpful to add flow to a specific part of the brain and (2) where exactly the extra flow will come from.
- CT Perfusion (CTP): This is an X-Ray-based test using radiation and dye to measure how much blood flow gets to the brain over time. We additionally administer a medication called acetazolamide, which normally causes blood vessels in the brain to dilate or enlarge. This typically causes the blood flow to increase to the brain. In patients with diseased or narrowed blood vessels, the blood vessels are typically already enlarged as much as possible, and thus do not have the ability to dilate anymore. This is termed “impaired autoregulation” since the vessels do not have the ability to auto-regulate.
- Transcranial Doppler (TCD): This is a non-invasive test using ultrasound technology that measures how fast blood flows through the brain blood vessels with and without a breath hold. Normally, when one holds their breath, they retain carbon dioxide which causes the blood vessels in the brain to dilate or open larger. This causes the speed of blood flow to decrease by a significant amount. In patients with narrowed or diseased blood vessels, the blood vessels do not react how they should and so the speed of blood flow does not reduce as we might expect it to. This is termed “impaired vaso reactivity”.
- Magnetic Resonance Imaging (MRI): This is a magnet-based, non-radiation scan used to look at the brain itself (not the blood vessels). This gives us the ability to see new and old strokes in the brain. We combine this with the information on the CTA and angiogram scans, information on autoregulation (CTD), and vasomotor reactivity (TCD) to determine (1) which parts of the brain have been injured so far and (2) which parts of the brain we can protect from further damage.
- Neuropsychological Testing: Each patient will undergo a formal evaluation by our neuropsychology team to assess various parts of cognition like memory, planning, language and other domains. Oftentimes, patients with MMD, MMS or SOD have problems in these domains that go undiagnosed. Our goal is to identify conditions and track them over time with our treatment to ensure that they do not worsen.