The Contribution of Common Surgically Implanted Hardware to Functional MR Imaging Artifacts.
OBJECTIVE
Blood oxygenation level-dependent MR imaging is increasingly used clinically to noninvasively assess cerebrovascular reactivity and/or language and motor function. However, many patients have metallic implants, which will induce susceptibility artifacts, rendering the functional information uninformative. Here, we calculate and interpret blood oxygenation level-dependent MR imaging artifact impact arising from surgically implanted hardware.


METHODS
A retrospective analysis of all blood oxygenation level-dependent MRIs (n = 343; B0 = 3T; TE = 35 ms; gradient echo EPI) acquired clinically (year range = 2006-2014) at our hospital was performed. Blood oxygenation level-dependent MRIs were most commonly prescribed for patients with cerebrovascular disease (n = 80) or patients undergoing language or motor localization (n = 263). Artifact volume (cubic centimeters) and its impact on clinical interpretation were determined by a board-certified neuroradiologist.


RESULTS
Mean artifact volume associated with intracranial hardware was 4.3 ± 3.2 cm(3) (range = 1.1-9.4 cm(3)). The mean artifact volume from extracranial hardware in patients with cerebrovascular disease was 28.4 ± 14.0 cm(3) (range = 6.1-61.7 cm(3)), and in patients with noncerebrovascular disease undergoing visual or motor functional mapping, it was 39.9 (3)± 27.0 cm(3) (range = 6.9-77.1 cm(3)). The mean artifact volume for ventriculoperitoneal shunts was 95.7 ± 39.3 cm(3) (range = 64.0-139.6 cm(3)). Artifacts had no-to-mild effects on clinical interpretability in all patients with intracranial implants. Extracranial hardware artifacts had no-to-moderate impact on clinical interpretability, with the exception of 1 patient with 12 KLS-Martin maxDrive screws with severe artifacts precluding clinical interpretation. All examined ventriculoperitoneal shunts resulted in moderate-to-severe artifacts, limiting clinical interpretation.


CONCLUSIONS
Blood oxygenation level-dependent MR imaging yields interpretable functional maps in most patients beyond a small (30-40 cm(3)) artifact surrounding the hardware. Exceptions were ventriculoperitoneal shunts, particularly those with programmable valves and siphon gauges, and large numbers of KLS-Martin maxDrive screws.
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.) aditi.desai@vanderbilt.edu.
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Desai
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.).
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Strother
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.).
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Faraco
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.).
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Morgan
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.).
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Ladner
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.).
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Dethrage
Pediatrics (L.C.J.).
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Jordan
From the Departments of Radiology and Radiological Sciences (A.A.D., M.K.S., C.C.F., V.L.M., T.R.L., L.M.D., M.J.D.) Division of Pediatric Neurology, Psychiatry (M.J.D.) Neurology (M.J.D.), Vanderbilt University School of Medicine, Nashville, Tennessee Department of Physics and Astronomy (M.J.D.), Vanderbilt University, Nashville, Tennessee.
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Donahue
D000328:Adult; D000368:Aged; D016477:Artifacts; D001921:Brain / Q000473:pathology*; D005260:Female; D059907:Functional Neuroimaging / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D019736:Prostheses and Implants; D012189:Retrospective Studies