Abstract
Background: Accurate measurement of lumbar spinal canal diameter (SCD) is essential for diagnosing lumbar canal stenosis (LCS) and for pre-surgical planning. The absence of unified radiological criteria for LCS makes knowledge of population-specific normal values critical. Magnetic resonance imaging (MRI) is the preferred modality for assessing lumbar spinal morphometry due to its superior soft-tissue contrast and absence of ionizing radiation. Objective: To establish normative MRI-based lumbar spinal canal diameter measurements at vertebral levels L1–L5 in the Khyber Pakhtunkhwa (KPK) population of Pakistan. Methods: A descriptive cross-sectional study was conducted at the MRI unit of Northwest General Hospital and Research Centre (NWGH), Peshawar, over six months. A convenience sample of 120 patients (aged 18–64 years) presenting with lower back pain and referred for lumbar MRI were enrolled. Canal diameters were measured at L1–L5 using Radiant DICOM software on a 0.35T open MRI scanner (Hitachi). Descriptive statistics and independent-samples t-tests were performed using SPSS v22. Results: Of 120 patients, 43 (35.8%) were male and 77 (64.2%) were female; mean age was 41.83 ± 11.44 years. Mean lumbar canal diameters were: L1 = 16.64 ± 1.69 mm, L2 = 14.93 ± 1.85 mm, L3 = 13.75 ± 1.78 mm, L4 = 13.36 ± 1.87 mm, L5 = 13.59 ± 2.25 mm. Overall canal diameter ranged from 11.0 to 20.4 mm. Males demonstrated wider canal dimensions at L1, L2, and L4, whereas females showed marginally wider dimensions at L3 and L5. Conclusion: This study provides population-specific normative lumbar spinal canal diameter values for the KPK region. The observed cephalocaudal narrowing pattern from L1 to L4, with slight widening at L5, is consistent with published data from other Asian populations. These reference values offer a clinically useful baseline for the diagnosis of lumbar canal stenosis in this underrepresented population.