Variation of Torg-Pavlov ratio with age, gender, vertebral level, dural sac area, and ethnicity in lumbar magnetic resonance imaging

Abstract

The objectives of the study were to provide normal values of the Torg-Pavlov ratio (TPR) of the lumbar spine in magnetic resonance imaging (MRI) for the Jordanian population and examine differences observed according to factors including age, gender, lumbar level, dural sac area, or ethnic group. Two hundred and eighteen lumbar MRIs from the Picture Archiving and Communication System were reviewed. These were collected from three main governmental hospitals, in North, Central, and South of Jordan. The mid-sagittal diameters of the vertebral body, spinal canal, and dural canal area were measured at all levels. Patients' gender and age were documented as well. Exclusion criteria were kyphoscoliosis alignments disorders, lumbar spinal canal compression regardless of the cause, vertebral bony disease (including fractures), and the presence of technical artifacts. Statistical analyses used descriptive and correlational methods. Comparisons were made between genders, age groups, lumbar level, dural sac area in the study population using independent t-test and one-way ANOVA tests, and between ethnicities by reviewing previous reports on subjects of different ethnicities. The mean TPR ratio for the study participants was 0.4502 ± 0.097. The value of TPR was widest in the 20-29-year-old group at all vertebral levels and in both males and females. Females had a significantly wider TPR than males (P = 0.003) in all age groups. TPR differed significantly between the five vertebral levels (P = 0.026). The difference in TPR between age groups was not statistically significant. TPR showed a positive significant correlation with dural sac (r = 0.203, P = 0.003). Comparison with the previous literature demonstrated variation in the TPR where Jordanian population had a lower TPR in comparison with Negros and Caucasoids whereas similar to Koreans, especially in females. There are significant differences in TPR according to gender, dural sac area, lumbar spinal level (except between L1 and L2), and ethnic group, but no significant difference with the age was found. The present study has identified normal values of Torg's ratio in the Jordanian population. Although the study may not be able to provide clear guidelines for use in clinical practice, it has still highlighted possible between countries variations and has identified differences in these values to different factors. Implications on clinical practice could be reflected on the diagnosis of lumbar spinal stenosis or on predicting the prognosis of lumbar spine injury.