3D virtual reconstruction and quantitative assessment of the human intervertebral disc's annulus fibrosus: a DTI tractography study.

The intervertebral disc's (IVD) annulus fibrosus (AF) retains the hydrostatic pressure of the nucleus pulposus (NP), controls the range of motion, and maintains the integrity of the motion segment. The microstructure of the AF is not yet fully understood and quantitative characterization is lacking, leaving a caveat in modern medicine's ability to prevent and treat disc failure (e.g., disc herniation). In this study, we show a reconstruction of the 3D microstructure of the fibers that constitute the AF via MRI diffusion tensor imaging (DTI) followed by fiber tracking. A quantitative analysis presents an anisotropic structure with significant architectural differences among the annuli along the width of the fibrous belt. These findings indicate that the outer annuli's construction reinforces the IVD while providing a sufficient degree of motion. Our findings also suggest an increased role of the outer annuli in IVD nourishment.

The Lumbar Lordosis in Males and Females, Revisited.

BACKGROUND: Whether differences exist in male and female lumbar lordosis has been debated by researchers who are divided as to the nature of variations in the spinal curve, their origin, reasoning, and implications from a morphological, functional and evolutionary perspective. Evaluation of the spinal curvature is constructive in understanding the evolution of the spine, as well as its pathology, planning of surgical procedures, monitoring its progression and treatment of spinal deformities. The aim of the current study was to revisit the nature of lumbar curve in males and females. METHODS: Our new automated method uses CT imaging of the spine to measure lumbar curvature in males and females. The curves extracted from 158 individuals were based on the spinal canal, thus avoiding traditional pitfalls of using bone features for curve estimation. The model analysis was carried out on the entire curve, whereby both local and global descriptors were examined in a single framework. Six parameters were calculated: segment length, curve length, curvedness, lordosis peak location, lordosis cranial peak height, and lordosis caudal peak height. PRINCIPAL FINDINGS: Compared to males, the female spine manifested a statistically significant greater curvature, a caudally located lordotic peak, and greater cranial peak height. As caudal peak height is similar for males and females, the illusion of deeper lordosis among females is due partially to the fact that the upper part of the female lumbar curve is positioned more dorsally (more backwardly inclined). CONCLUSIONS: Males and females manifest different lumbar curve shape, yet similar amount of inward curving (lordosis). The morphological characteristics of the female spine were probably developed to reduce stress on the vertebral elements during pregnancy and nursing.

Identifying and classifying hyperostosis frontalis interna via computerized tomography.

The aim of this study was to recognize the radiological characteristics of hyperostosis frontalis interna (HFI) and to establish a valid and reliable method for its identification and classification. A reliability test was carried out on 27 individuals who had undergone a head computerized tomography (CT) scan. Intra-observer reliability was obtained by examining the images three times, by the same researcher, with a 2-week interval between each sample ranking. The inter-observer test was performed by three independent researchers. A validity test was carried out using two methods for identifying and classifying HFI: 46 cadaver skullcaps were ranked twice via computerized tomography scans and then by direct observation. Reliability and validity were calculated using Kappa test (SPSS 15.0). Reliability tests of ranking HFI via CT scans demonstrated good results (K > 0.7). As for validity, a very good consensus was obtained between the CT and direct observation, when moderate and advanced types of HFI were present (K = 0.82). The suggested classification method for HFI, using CT, demonstrated a sensitivity of 84%, specificity of 90.5%, and positive predictive value of 91.3%. In conclusion, volume rendering is a reliable and valid tool for identifying HFI. The suggested three-scale classification is most suitable for radiological diagnosis of the phenomena. Considering the increasing awareness of HFI as an early indicator of a developing malady, this study may assist radiologists in identifying and classifying the phenomena.

Ligamentum flavum thickness in normal and stenotic lumbar spines.

STUDY DESIGN: A descriptive computed tomography (CT) study of the ligamentum flavum (LF) thickness in individuals with normal and stenotic lumbar spines. OBJECTIVE: To establish standards for normal and pathologic range of LF thickness and its asymmetry as indicated in CT images and to examine its association with vertebral body size, age, and gender. SUMMARY OF BACKGROUND DATA: LF lines a considerable part of the posterior and lateral walls of the spinal canal and is a major role contributor to spinal canal stenosis. Due to methodologic deficiencies (e.g., small sample size, lack of control for vertebral body size, gender, and age), the normal range of LF thickness is still controversial. Furthermore, data on important aspect of LF thickness such as left-right differences are missing. METHODS: Two groups of individuals were studied. The first group included 65 individuals with lumbar spinal stenosis (LSS) (mean age: 66 +/- 9.7 years) and the second, 150 individuals (mean age: 52 +/- 19 years) without LSS-related symptoms. LF thickness was measured on CT images (Philips Brilliance 64), obtained from axial plane scan at the intervertebral disc level. Measurements were performed at the levels of L3-L4, L4-L5, and L5-S1. Analysis of variance and t test were carried out to evaluate the association between LF thickness and demographic factors. RESULTS: Absolute and relative LF thickness were significantly greater in the LSS group at the levels of L3-L4 and L4-L5 on both sides, compared to control group (P < 0.05). LF thickness was independent of gender (absolute and relative thickness). Even though LF thickness at all levels significantly increases with age, significant changes after the age of 60 occurred only at L3-L4. Significant asymmetry in LF thickness was found at L3-L4 (2.9 +/- 0.90 mm on the right vs. 2.76 +/- 0.90 mm on the left) and L5-S1 (3.42 +/- 1.1 mm on the right vs. 3.22 +/- 1.22 mm on the left) (P < 0.05). CONCLUSION: LF thickness is an age-dependent and gender-independent phenomenon. LF is significantly thicker on the right side. The borderline between normal and pathologic LF thickness should not be set at 4 mm.

Spine curve modeling for quantitative analysis of spinal curvature.

Spine curvature and posture are important to sustain healthy back. Incorrect spine configuration can add strain to muscles and put stress on the spine, leading to low back pain (LBP). We propose new method for analyzing spine curvature in 3D, using CT imaging. The proposed method is based on two novel concepts: the spine curvature is derived from spinal canal centerline, and evaluation of the curve is carried out against a model based on healthy individuals. We show results of curvature analysis of healthy population, pathological (scoliosis) patients, and patients having nonspecific chronic LBP.