ARRS 2022 Abstracts

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E1754. Seeing Through the Smoke: A Radiologist’s Review of Moyamoya
Authors
  1. Vishwas Tiwari; Henry Ford Hospital
  2. Nathan Hyson; Henry Ford Hospital
  3. Horia Marin; Henry Ford Hospital
  4. Brent Griffith; Henry Ford Hospital
  5. Ishani Dalal; Henry Ford Hospital
Background
Moyamoya is a chronic cerebrovascular disease that was first described by Japanese researchers in the 1950s and 60s. This condition is typified by progressive stenosis of the distal internal carotid arteries (ICAs) and their major branches; the name itself refers to the smoke-like appearance of the formed intracranial collateral vessels on angiography. The purpose of this exhibit is to explore the imaging evaluation of moyamoya within the broader context of the disease.

Educational Goals / Teaching Points
The first goal of this exhibit is to briefly examine the epidemiology and spectrum of clinical presentation of moyamoya, followed by the pathogenesis of the disease. The imaging findings are described on CTA, MRI, and digital subtraction angiography (DSA) – including a review of the angiographic staging. The function of SPECT in the evaluation and management of moyamoya is examined in detail, and within the context of cerebrovascular physiology. Lastly, various treatment options are described with an emphasis on the radiologist’s role.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The pathology underlying moyamoya is not completely understood. It is thought to involve a combination of genetic factors, angiogenesis, and dilatation of pre-existing penetrating arteries. DSA is the gold standard for diagnosis of moyamoya, and it usually demonstrates narrowing of the distal ICAs, with a surrounding network of collaterals resulting in the familiar “puff of smoke” appearance. The Suzuki system describes the anatomical progression of the disease with six stages, beginning with just narrowing of the terminal ICAs and ending with the development of abnormal transdural and transosseous external carotid anastomosis. Both primary and secondary forms of moyamoya are seen. Supporting imaging findings can be seen on CT, CTA, and MRI. Ischemic and hemorrhagic strokes are routinely evaluated with these modalities, and often what is first seen when a patient with moyamoya is imaged. Findings such as the “ivy” sign or “brush” sign can also be seen on MRI and are relatively specific. SPECT is a valuable tool that can be used to monitor disease, determine the need for surgery, and track postsurgical changes based on measurements of cerebral blood flow (CBF) before and after acetazolamide administration. As moyamoya tends to involve the anterior circulation, SPECT usually demonstrates low CBF in the frontal, parietal, and temporal regions.

Conclusion
Moyamoya is a rare condition with a characteristic appearance on angiography. The radiologist plays a key role in the diagnosis, surveillance, and often the treatment of moyamoya disease. Multiple imaging modalities can support the diagnosis, such as CT and MRI. SPECT can be used to monitor pertinent cerebrovascular parameters, which help determine the management and prognosis of patients with this condition.