Cerebellar tonsil ectopia measurement in type I Chiari malformation patients show poor inter-operator reliability

• Authors: Braden J. Lawrence, University of Idaho; Aintzane Urbizu, Duke University; Philip A. Allen, University of Akron; Francis Loth, University of Akron; R. Shane Tubbs, Seattle Science Foundation; Alexander C. Bunck, University Hospital Cologne; Jan-Robert Kroeger, University Hospital Cologne; Brandon G. Rocque, University of Alabama Birmingham; Casey Madura, Helen DeVos Children's Hospital; Jason A. Chen, University of California Los Angeles; Mark G. Luciano, Johns Hopkins University; Richard G. Ellenbogen, University of Washington; John Oshinski, Emory University; Bermans J. Iskandar, University of Wisconsin; Bryn A. Martin, University of Idaho
• Journal Title: Fluids and Barriers of the CNS
• Volume: Volume 15, Number 1
• Publisher: BMC (part of Springer Nature) | 2018-12-17, Pages 33-33
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1186/s12987-018-0118-1
• Subjects: Biology, Neuroscience; Engineering, Biomedical; Health Sciences, Medicine and Surgery
• Keywords: Science & Technology; Life Sciences & Biomedicine; Neurosciences; Neurosciences & Neurology; Cerebellar tonsil; Inter-operator reliability; Morphometric; MRI; Syringomyelia; Type 1 Chiari malformation; CEREBROSPINAL-FLUID DYNAMICS; NATURAL-HISTORY; POSTERIOR-FOSSA; DECOMPRESSION; CHILDREN; POSITION; FLOW; RECURRENCE; PULSATIONS; ASYMMETRY

Abstract

Background: Type 1 Chiari malformation (CM-I) has been historically defined by cerebellar tonsillar position (TP) greater than 3-5 mm below the foramen magnum (FM). Often, the radiographic findings are highly variable, which may influence the clinical course and patient outcome. In this study, we evaluate the inter-operator reliability (reproducibility) of MRI-based measurement of TP in CM-I patients and healthy controls. Methods: Thirty-three T2-weighted MRI sets were obtained for 23 CM-I patients (11 symptomatic and 12 asymptomatic) and 10 healthy controls. TP inferior to the FM was measured in the mid-sagittal plane by seven expert operators with reference to McRae's line. Overall agreement between the operators was quantified by intraclass correlation coefficient (ICC). Results: The mean and standard deviation of cerebellar TP measurements for asymptomatic (CM-Ia) and symptomatic (CM-Is) patients in mid-sagittal plane was 6.38 ± 2.19 and 9.57 ± 2.63 mm, respectively. TP measurements for healthy controls was 0.48 ± 2.88 mm. The average range of TP measurements for all data sets analyzed was 7.7 mm. Overall operator agreement for TP measurements was relatively high with an ICC of 0.83. Conclusion: The results demonstrated a large average range (7.7 mm) of measurements among the seven expert operators and support that, if economically feasible, two radiologists should make independent measurements before radiologic diagnosis of CM-I and surgery is contemplated. In the future, an objective diagnostic parameter for CM-I that utilizes automated algorithms and results in smaller inter-operator variation may improve patient selection.