title: Prior Infarcts, Reactivity, and Angiography in Moyamoya Disease (PIRAMD): a scoring system for moyamoya severity based on multimodal hemodynamic imaging.
abstract: OBJECTIVE Quantification of the severity of vasculopathy and its impact on parenchymal hemodynamics is a necessary prerequisite for informing management decisions and evaluating intervention response in patients with moyamoya. The authors performed digital subtraction angiography and noninvasive structural and hemodynamic MRI, and they outline a new classification system for patients with moyamoya that they have named Prior Infarcts, Reactivity, and Angiography in Moyamoya Disease (PIRAMD). METHODS Healthy control volunteers (n = 11; age 46 ± 12 years [mean ± SD]) and patients (n = 25; 42 ± 13.5 years) with angiographically confirmed moyamoya provided informed consent and underwent structural (T1-weighted, T2-weighted, FLAIR, MR angiography) and hemodynamic (T2*- and cerebral blood flow-weighted) 3-T MRI. Cerebrovascular reactivity (CVR) in the internal carotid artery territory was assessed using susceptibility-weighted MRI during a hypercapnic stimulus. Only hemispheres without prior revascularization were assessed. Each hemisphere was considered symptomatic if localizing signs were present on neurological examination and/or there was a history of transient ischemic attack with symptoms referable to that hemisphere. The PIRAMD factor weighting versus symptomatology was optimized using binary logistic regression and receiver operating characteristic curve analysis with bootstrapping. The PIRAMD finding was scored from 0 to 10. For each hemisphere, 1 point was assigned for prior infarct, 3 points for reduced CVR, 3 points for a modified Suzuki Score ≥ Grade II, and 3 points for flow impairment in ≥ 2 of 7 predefined vascular territories. Hemispheres were divided into 3 severity grades based on total PIRAMD score, as follows: Grade 1, 0-5 points; Grade 2, 6-9 points; and Grade 3, 10 points. RESULTS In 28 of 46 (60.9%) hemispheres the findings met clinical symptomatic criteria. With decreased CVR, the odds ratio of having a symptomatic hemisphere was 13 (95% CI 1.1-22.6, p = 0.002). The area under the curve for individual PIRAMD factors was 0.67-0.72, and for the PIRAMD grade it was 0.845. There were 0/8 (0%), 10/18 (55.6%), and 18/20 (90%) symptomatic PIRAMD Grade 1, 2, and 3 hemispheres, respectively. CONCLUSIONS A scoring system for total impairment is proposed that uses noninvasive MRI parameters. This scoring system correlates with symptomatology and may provide a measure of hemodynamic severity in moyamoya, which could be used for guiding management decisions and evaluating intervention response.
authors.affiliation: Department of Radiology.
authors.forename: Travis R
authors.initials: TR
authors.lastname: Ladner
authors.affiliation: Department of Radiology.
authors.forename: Manus J
authors.initials: MJ
authors.lastname: Donahue
authors.affiliation: Department of Radiology.
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Arteaga
authors.affiliation: Department of Radiology.
authors.forename: Carlos C
authors.initials: CC
authors.lastname: Faraco
authors.affiliation: Department of Radiology.
authors.forename: Brent A
authors.initials: BA
authors.lastname: Roach
authors.affiliation: Department of Radiology.
authors.forename: L Taylor
authors.initials: LT
authors.lastname: Davis
authors.affiliation: Division of Pediatric Neurology, Department of Pediatrics; and.
authors.forename: Lori C
authors.initials: LC
authors.lastname: Jordan
authors.affiliation: Departments of Neurology and Neurosurgery, Vanderbilt University Medical Center, Nashville, Tennessee.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Froehler
authors.affiliation: Department of Radiology.
authors.forename: Megan K
authors.initials: MK
authors.lastname: Strother
mesh_terms: D000293:Adolescent; D000328:Adult; D015901:Angiography, Digital Subtraction; D002560:Cerebrovascular Circulation / Q000502:physiology; D002648:Child; D006801:Humans; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D009072:Moyamoya Disease / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D064847:Multimodal Imaging; D012720:Severity of Illness Index; D055815:Young Adult
keywords: ASPECTS = Alberta Stroke Program Early CT Score; AUC = area under the curve; BOLD = blood oxygen level–dependent; CBF = cerebral blood flow; CBV = cerebral blood volume; CVR = cerebrovascular reactivity; DSA = digital subtraction angiography; ETCO2 = end-tidal CO2; ICA = internal carotid artery; MCA = middle cerebral artery; PIRAMD = Prior Infarcts, Reactivity, and Angiography in Moyamoya Disease; ROC = receiver operating characteristic; Xe-CT = xenon-enhanced CT; cerebrovascular reactivity; hemodynamic; mSS = modified Suzuki score; magnetic resonance imaging; moyamoya; vascular disorders