Standardization and validation of a novel and simple method to assess lumbar dural sac size

Abstract

AIMTo develop and validate a simple, reproducible method to assess dural sac size using standard imaging technology.MATERIALS AND METHODSThis study was institutional review board-approved. Two readers, blinded to the diagnoses, measured anterior–posterior (AP) and transverse (TR) dural sac diameter (DSD), and AP vertebral body diameter (VBD) of the lumbar vertebrae using MRI images from 53 control patients with pre-existing MRI examinations, 19 prospectively MRI-imaged healthy controls, and 24 patients with Marfan syndrome with prior MRI or CT lumbar spine imaging. Statistical analysis utilized linear and logistic regression, Pearson correlation, and receiver operating characteristic (ROC) curves.RESULTSAP-DSD and TR-DSD measurements were reproducible between two readers (r = 0.91 and 0.87, respectively). DSD (L1–L5) was not different between male and female controls in the AP or TR plane (p = 0.43; p = 0.40, respectively), and did not vary by age (p = 0.62; p = 0.25) or height (p = 0.64; p = 0.32). AP-VBD was greater in males versus females (p = 1.5 × 10−8), resulting in a smaller dural sac ratio (DSR) (DSD/VBD) in males (p = 5.8 × 10−6). Marfan patients had larger AP-DSDs and TR-DSDs than controls (p = 5.9 × 10−9; p = 6.5 × 10−9, respectively). Compared to DSR, AP-DSD and TR-DSD better discriminate Marfan from control subjects based on area under the curve (AUC) values from unadjusted ROCs (AP-DSD p < 0.01; TR-DSD p = 0.04).CONCLUSIONIndividual vertebrae and L1–L5 (average) AP-DSD and TR-DSD measurements are simple, reliable, and reproducible for quantitating dural sac size without needing to control for gender, age, or height.

Enlarged Dural Sac in Idiopathic Bronchiectasis Implicates Heritable Connective Tissue Gene Variants

“…An additional 24 subjects carried a genetic or clinical diagnosis of Marfan syndrome and had preexisting MR imaging ORIGINAL RESEARCH or CT examinations of the lumbosacral spine available for measurement (34). Exclusion criteria for all subjects included severe thoracic or lumbar scoliosis (Cobb angle, >30 degrees), thoracic or lumbar spinal surgery, spinal stenosis, or spinal injury.…”

“…Control subjects (n = 72) without lung or spinal disease or evidence of heritable connective tissue disorders were imaged as previously described (34). Subjects with cystic fibrosis (n = 29) were confirmed to carry two disease-causing mutations in CFTR and served to control for the possibility that coughing might cause increased intracranial and intrathecal pressure and thereby affect dural size.…”

“…Both preexisting and prospective lumbar MR imaging examinations were performed as described by Daniels and colleagues (34). Additional details are provided in the online supplement.…”

“…Dural sac size can easily be measured using sagittal images of the lumbar spine obtained by magnetic resonance (MR) imaging or computed tomography (CT) (32)(33)(34). Measurements obtained in this way can be reproduced by readers with different experience using a standardized and validated method, and they are not influenced by age, sex, height, or race (34).…”

“…Measurements obtained in this way can be reproduced by readers with different experience using a standardized and validated method, and they are not influenced by age, sex, height, or race (34).…”