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PubMed This is a summary of 18 peer-reviewed journal articles Updated
Neurosurgery

Getting a Clear Picture: Diagnostic Tests and Imaging

At a Glance

Moyamoya diagnosis combines images of the brain’s blood vessels with tests of blood flow. Catheter angiography maps narrowed arteries and backup vessels, while MRI, SPECT, PET, or ASL can show whether brain tissue has enough reserve.

Diagnosing Moyamoya is like putting together a complex puzzle. Because the disease changes over time, doctors use a combination of “structural” pictures to see the vessels and “functional” tests to see how much blood is actually reaching the brain tissue.

The Reference Standard: Catheter Angiography

While an MRI or CT scan often provides the first clue, Digital Subtraction Angiography (DSA) is considered the reference standard for vascular imaging and confirming Moyamoya [1][2].

During this procedure, a doctor inserts a small catheter (usually through the groin or wrist) and injects a special contrast dye directly into the arteries leading to the brain. This allows for a high-definition view of exactly how the blood flows. It is often essential for:

  • Surgical Planning: Showing the surgeon exactly which “donor” vessels are available for a bypass [3].
  • Checking for Aneurysms: Identifying weak spots or bulges in the fragile collateral vessels that might be at risk of bleeding [4].
  • Detailed Mapping: Seeing the “hidden” bypasses the brain has already tried to make on its own [5].

What to expect: DSA is invasive and carries procedure-specific risks including radiation exposure, contrast reaction, bleeding at the catheter site, and a small risk of stroke. While DSA is crucial for many, MRI/MRA may be sufficient in some diagnostic contexts. Discuss with your doctor why DSA is recommended for you.

The Suzuki Stages: Describing the Vessels

Doctors use an angiographic grading system called the Suzuki Stages (I through VI) to describe the appearance of the vessels on an angiogram [6][7]:

  1. Stage I: Narrowing begins at the end of the internal carotid artery.
  2. Stage II: The first “puff of smoke” collaterals appear at the base of the brain.
  3. Stage III: The “puff of smoke” is at its most intense.
  4. Stage IV: The “puff of smoke” begins to fade as the brain tries to get blood from outside the skull.
  5. Stage V: The “puff of smoke” vessels mostly disappear because the main arteries are nearly completely closed.
  6. Stage VI: The main arteries are totally closed, and the brain relies entirely on alternative blood sources.

Note: Suzuki staging is a description of vessel patterns. Stages can differ between the left and right sides of the brain, do not directly measure tissue perfusion, and do not by themselves determine whether surgery is needed.

The 2021 Diagnostic Shift

For many years, a diagnosis of Moyamoya Disease required the narrowing to be present on both sides of the brain (bilateral). However, international guidelines were updated in 2021 [8][9]. Doctors now recognize that Moyamoya often starts on one side and may stay that way for a long time. Today, you can be diagnosed with the disease even if only one side is affected (unilateral), provided the characteristic angiopathy is present and mimics (like atherosclerosis) are excluded [8].

Measuring “Brain Power”: Cerebrovascular Reserve (CVR)

Having narrowed vessels is only half the story. The other half is how well your brain handles that restriction, measured by Cerebrovascular Reserve (CVR).

Think of CVR as the brain’s “emergency backup” capacity. In a healthy brain, if you start exercising, blood vessels dilate (widen) to let more blood through. In Moyamoya, the vessels are often already dilated to their maximum just to keep things running at rest (a state sometimes called “misery perfusion”). They have no “reserve” left. If blood flow drops further, blood might actually be drawn away from struggling areas to feed healthy ones—a phenomenon known as “steal” [10][11].

Doctors measure CVR using perfusion imaging (like SPECT, PET, or Arterial Spin Labeling MRI) [12][13].

  • ASL (Arterial Spin Labeling): A non-radiation MRI technique that tracks blood transit; particularly helpful for children, though it has limitations [14][15].
  • PET/SPECT: These scans use a radioactive tracer to map blood flow, oxygen use, or metabolism [13][16].

They often give a medication called acetazolamide (Diamox) during the scan to stress test the vessels. Because this challenge can provoke headaches or neurologic symptoms and produce “steal” in severely impaired territories, testing requires specialist monitoring [17][18]. CVR is one important piece of a clinical decision that also includes your symptoms, anatomy, and overall context.

Common questions in this guide

What is a catheter angiogram, or DSA, used for in Moyamoya disease?
Digital subtraction angiography, or DSA, is an invasive imaging test that gives a detailed view of narrowed arteries and collateral blood vessels. It can help with bypass planning and identify aneurysms or other fragile vessels. Because it uses a catheter and contrast dye, it carries risks such as bleeding, contrast reaction, radiation exposure, and a small risk of stroke.
What do the Suzuki stages mean on a Moyamoya angiogram?
Suzuki stages I through VI describe how the arteries and collateral “puff of smoke” vessels look on angiography. The stages progress from early narrowing to reliance on blood supplies from outside the skull. A stage does not measure tissue blood flow or alone determine whether surgery is needed, and the stages can differ between the two sides of the brain.
Can Moyamoya disease be diagnosed when only one side is affected?
Yes. Under updated 2021 criteria, characteristic Moyamoya angiopathy on one side can support a diagnosis after conditions that mimic it, such as atherosclerosis, have been excluded. Doctors may continue monitoring because the vessel changes can progress or affect the other side over time.
How does cerebrovascular reserve testing show whether my brain has enough blood flow?
Cerebrovascular reserve testing measures how much blood flow can increase when the brain’s vessels are challenged. SPECT, PET, or arterial spin labeling MRI may be performed with acetazolamide; areas with little reserve may show a reduced response or blood-flow “steal.” Doctors interpret CVR together with symptoms and vessel anatomy rather than using it alone.
Is MRI or MRA enough, or do I need DSA for Moyamoya disease?
MRI or MRA may be sufficient in some diagnostic situations and does not require a catheter. DSA remains the reference standard when detailed vessel mapping is needed, including surgical planning or checking collateral vessels and aneurysms. Your clinician can explain why one test or a combination of tests is appropriate for your case.
What side effects can happen during an acetazolamide CVR test?
Acetazolamide can provoke headaches or neurologic symptoms during the challenge, and severely impaired areas may show blood-flow “steal.” Because the test stresses the brain’s blood-flow response, it requires specialist monitoring. Ask the testing team which symptoms should be reported during or after the scan.

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Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.What is my (or my child's) current Suzuki stage, and how does it fit into the overall picture of our symptoms and perfusion tests?
  2. 2.Based on the 2021 diagnostic criteria, is my condition classified as unilateral or bilateral?
  3. 3.Why are you recommending a catheter angiogram (DSA) over just using non-invasive MRI/MRA for our specific case?
  4. 4.How did my brain perform on the CVR test—is there any 'steal' or 'misery perfusion' occurring?
  5. 5.Are the tiny 'puff of smoke' vessels currently growing (Stage II/III) or starting to disappear (Stage V/VI)?

References

References (18)
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    Imaging-Based Diagnostic Approaches in Moyamoya Disease: A Scoping Review.

    Novillo-Solis C, Salvador-Orbea M, Morales-Acosta A, Leon-Rojas JE

    Journal of clinical medicine 2026; (15(6)) doi:10.3390/jcm15062410.

    PMID: 41899333
  2. 2

    Clinical Characteristics and Multi-Model Imaging Analysis of Moyamoya Disease: An Observational Study.

    Ling H, Huang H, Fu B, et al.

    The Journal of craniofacial surgery 2025; (36(1)):e45-e49 doi:10.1097/SCS.0000000000010765.

    PMID: 39436989
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    [Variants of collateral cerebral circulation in moyamoya disease].

    Shulgina AA, Lukshin VA, Usachev DY

    Zhurnal voprosy neirokhirurgii imeni N. N. Burdenko 2023; (87(3)):20-28 doi:10.17116/neiro20238703120.

    PMID: 37325823
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    The angiographic presentation of European Moyamoya angiopathy.

    Pilgram-Pastor S, Chapot R, Kraemer M

    Journal of neurology 2022; (269(2)):997-1006 doi:10.1007/s00415-021-10684-6.

    PMID: 34240321
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    Angiographic Analysis of Natural Anastomoses between the Posterior and Anterior Cerebral Arteries in Moyamoya Disease and Syndrome.

    Bonasia S, Ciccio G, Smajda S, et al.

    AJNR. American journal of neuroradiology 2019; (40(12)):2066-2072 doi:10.3174/ajnr.A6291.

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    Magnetic Resonance Angiography Alone Is Insufficient for Diagnosis and Surgical Planning in Children With Moyamoya.

    Lehman LL, Wu C, Kaseka ML, et al.

    Pediatric neurology 2024; (159()):1-3 doi:10.1016/j.pediatrneurol.2024.06.008.

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    Longitudinal anterior-to-posterior shift of collateral channels in patients with moyamoya disease: an implication for its hemorrhagic onset.

    Yamamoto S, Hori S, Kashiwazaki D, et al.

    Journal of neurosurgery 2019; (130(3)):884-890 doi:10.3171/2017.9.JNS172231.

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    Diagnostic Criteria for Moyamoya Disease - 2021 Revised Version.

    Kuroda S, Fujimura M, Takahashi J, et al.

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    PMID: 35613882
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    Diagnosis of moyamoya disease: international standard and regional differences.

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    Neurologia medico-chirurgica 2015; (55(3)):189-93 doi:10.2176/nmc.ra.2014-0307.

    PMID: 25739428
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    Simultaneous phase-contrast MRI and PET for noninvasive quantification of cerebral blood flow and reactivity in healthy subjects and patients with cerebrovascular disease.

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    Journal of magnetic resonance imaging : JMRI 2020; (51(1)):183-194 doi:10.1002/jmri.26773.

    PMID: 31044459
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    Revascularization improves vascular hemodynamics - a study assessing cerebrovascular reserve and transit time in Moyamoya patients using MRI.

    Zhao MY, Armindo RD, Gauden AJ, et al.

    Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism 2023; (43(2_suppl)):138-151 doi:10.1177/0271678X221140343.

    PMID: 36408536
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    Assessment of cerebrovascular reserve using acetazolamide brain perfusion SPECT in Moyamoya disease.

    Goyal H, Chakraborty D, Kumar SA, Pandey S

    Asia Oceania journal of nuclear medicine & biology 2026; (14(1)):90-97 doi:10.22038/aojnmb.2025.89265.1647.

    PMID: 41626117
  13. 13

    Accuracy of brain perfusion single-photon emission computed tomography for detecting misery perfusion in adult patients with symptomatic ischemic moyamoya disease.

    Setta K, Kojima D, Shimada Y, et al.

    Annals of nuclear medicine 2018; (32(9)):611-619 doi:10.1007/s12149-018-1283-7.

    PMID: 30030783
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    Identifying Hypoperfusion in Moyamoya Disease With Arterial Spin Labeling and an [15O]-Water Positron Emission Tomography/Magnetic Resonance Imaging Normative Database.

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    Stroke 2019; (50(2)):373-380 doi:10.1161/STROKEAHA.118.023426.

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    Arterial spin-labeling cerebral perfusion changes after revascularization surgery in pediatric moyamoya disease and syndrome.

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    Quantitative H2[(15)O]-PET in Pediatric Moyamoya Disease: Evaluating Perfusion before and after Cerebral Revascularization.

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    Long term outcome and predictors of ischemic stroke recurrence in adult moyamoya disease.

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    Cerebrovascular Events During Pregnancy and Puerperium Resulting from Preexisting Moyamoya Disease: Determining the Risk of Ischemic Events Based on Hemodynamic Status Assessment Using Brain Perfusion Single-Photon Emission Computed Tomography.

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This page about Moyamoya diagnostic tests is for informational purposes only and does not constitute medical advice. Your treating specialist should recommend the safest tests and interpret your results in light of your symptoms and anatomy.