Rapid-sequence Brain Magnetic Resonance Imaging for Chiari I Abnormality

J Neurosurg Pediatr. 2018 Aug;22(2):158-164. doi: 10.3171/2018.2.PEDS17523. Epub 2018 May 11.

Abstract

OBJECTIVE Fast magnetic resonance imaging (fsMRI) sequences are single-shot spin echo images with fast acquisition times that have replaced CT scans for many conditions. Introduced as a means of evaluating children with hydrocephalus and macrocephaly, these sequences reduce the need for anesthesia and can be more cost-effective, especially for children who require multiple surveillance scans. However, the role of fsMRI has yet to be investigated in evaluating the posterior fossa in patients with Chiari I abnormality (CM-I). The goal of this study was to examine the diagnostic performance of fsMRI in evaluating the cerebellar tonsils in comparison to conventional MRI. METHODS The authors performed a retrospective analysis of 18 pediatric patients with a confirmed diagnosis of CM-I based on gold-standard conventional brain MRI and 30 controls without CM-I who had presented with various neurosurgical conditions. The CM-I patients were included if fsMRI studies had been obtained within 1 year of conventional MRI with no surgical intervention between the studies. Two neuroradiologists reviewed the studies in a blinded fashion to determine the diagnostic performance of fsMRI in detecting CM-I. For the CM-I cohort, the fsMRI and T2-weighted MRI exams were randomized, and the blinded reviewers performed tonsillar measurements on both scans. RESULTS The mean age of the CM-I cohort was 7.39 years, and 50% of these subjects were male. The mean time interval between fsMRI and conventional T2-weighted MRI was 97.8 days. Forty-four percent of the subjects had undergone imaging after posterior fossa decompression. The sensitivity and specificity of fsMRI in detecting CM-I was 100% (95% CI 71.51%-100%) and 92.11% (95% CI 78.62%-98.34%), respectively. If only preoperative patients are considered, both sensitivity and specificity increase to 100%. The authors also performed a cost analysis and determined that fsMRI was significantly cost-effective compared to T2-weighted MRI or CT. CONCLUSIONS Despite known limitations, fsMRI may serve as a useful diagnostic and surveillance tool for CM-I. It is more cost-effective than full conventional brain MRI and decreases the need for sedation in young children.

Keywords: CM-I = Chiari I abnormality; Chiari I abnormality; Chiari malformation type I; FSE = fast spin echo; NPV = negative predictive value; PPV = positive predictive value; SSFSE = single-shot FSE; fast MRI; fsMRI = fast magnetic resonance imaging; magnetic resonance imaging.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Adolescent
  • Adult
  • Arnold-Chiari Malformation / diagnostic imaging*
  • Brain / diagnostic imaging*
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Infant
  • Infant, Newborn
  • Magnetic Resonance Imaging*
  • Male
  • Palatine Tonsil / diagnostic imaging
  • Retrospective Studies
  • Sensitivity and Specificity
  • Young Adult