Lumbar vertebra morphometry and stereological assesment of intervertebral space volumetry: A methodological study

Measurement of Intervertebral Disc Heights in the Lumbar Spine. Comparison of X-Ray and Magnetic Resonance Imaging, Method of Measurement and Determination of Inter-observer Reliability

PURPOSE

Retrospective radiological examination (X-ray and MRI) aims to investigate the diagnostic value of various methods of measurement with regard to the determination of the intervertebral disc heights of the lumbar spine.

METHODS

Of 130 patients without detectable damage to the intervertebral discs, the X-ray and MRI images of the lumbar spine were evaluated. The measurements were made either in the center line (Hurxthal) or in the 2-point method according to Dabbs or in the 3-point method according to Fyllos.

RESULTS

The average intervertebral disc height for all measured segments was 8.8 mm (SD 1.4 mm). In the Hurxthal measurement, the significantly (p < 0.001) highest values were measured with an average of 9.1 mm (SD 1.3 mm). The average readings for the Fyllos method were 7.5 mm (SD 1.2 mm) and according to Dabbs 6.7 mm (SD 1.2 mm). The measured values of Observer I were on average 1.2 mm (SD 0.3 mm) smaller than those of Observer II (p < 0.001). The highest interobserver correlation was found in the measurements in projection radiography in the AP method according to Dabbs and Fyllos. The measured values in men were 0.5 mm (SD 0.01 mm) larger than in women (p < 0.001), regardless of the method. The height of the intervertebral discs increases significantly until the age of 40, but beyond the age of 40, the height of the intervertebral discs either remains constant or falls off slightly, but not significantly. The lordosis angle of the lumbar spine and the concavity index of the vertebral bodies showed no correlation with the measured disc heights.

CONCLUSIONS

The radiological measurements to determine the intervertebral disc height have only moderate reliability. The results of X-rays are superior to those of MRI examination. The most accurate results are provided by measurements based on exact landmarks of the vertebral bodies. The method according to Dabbs seems to be the most accurate at the moment. There is no clear age-atypical chondrosis in patients without intervertebral disc damage.

Morphology and Composition of Lumbar Intervertebral Discs: Comparative Analyses of Manual Measurement and Computer-Assisted Algorithms

BACKGROUND

The morphology and internal composition, particularly the nucleus-to-cross sectional area (NP-to-CSA) ratio of the lumbar intervertebral discs (IVDs), is important information for finite element models (FEMs) of spinal loadings and biomechanical behaviors, and, yet, this has not been well investigated and reported.

METHODS

Anonymized MRI scans were retrieved from a previously established database, including a total of 400 lumbar IVDs from 123 subjects (58 F and 65 M). Measurements were conducted manually by a spine surgeon and using two computer-assisted segmentation algorithms, i.e., fuzzy C-means (FCM) and region growing (RG). The respective results were compared. The influence of gender and spinal level was also investigated.

RESULTS

Ratios derived from manual measurements and the two computer-assisted algorithms (FCM and RG) were 46%, 39%, and 38%, respectively. Ratios derived manually were significantly larger.

CONCLUSIONS

Computer-assisted methods provide reliable outcomes that are traditionally difficult for the manual measurement of internal composition. FEMs should consider the variability of NP-to-CSA ratios when studying the biomechanical behavior of the spine.

Relation of lumbar intervertebral disc height and severity of disc degeneration based on Pfirrmann scores

Background

Disc height (DH) change is considered one of the most critical factors in assessing intervertebral disc degeneration (IVD). Pfirrmann et al. developed a scoring system for disc degeneration evaluation based on changes in DH in magnetic resonance imaging (MRI). While the relationship between DH measurements and Pfirrmann scores for disc degeneration has been explored, the validity of different DH measuring techniques or their connection with disc degeneration is yet uncertain. The present study investigates intra-rater and inter-rater agreement and reliability of different DH measurement methods on MRI and evaluates the relationship between different DH measurement methods and Pfirrmann scores of IVD degeneration, as well as between different Pfirrmann scores and clinical outcomes.

Methods

Adult patients with MRI scans of the lumbar spine were recruited. Eight DH measuring techniques were tested for intra-rater and inter-rater agreement and reliability. Bland and Altman's Limits of Agreement (LOA) was used to evaluate intra-rater and inter-rater agreements. Intra-rater and inter-rater reliability were evaluated using intra-class correlations (ICC) with 95 % confidence intervals (95 % CI). The association between DH and Pfirrmann scores was examined using one-way ANOVA.

Results

Excellent intra-rater reliability was reported for 332 participants on DH (ranging from 0.912 (0.901, 0.923) to 0.973 (0.964, 0.981) and from 0.902 (0.892, 0.915) to 0.975 (0.962, 0.985) by two independent raters). All measuring methods had high intra-rater agreement, except for methods 4 and 5. All methods had good-to-excellent of inter-rater reliability on DH (ICCs ranging from 0.812 (0.795, 0.828) to 0.995 (0.994, 0.995)) except for the posterior disc material length of method 5 (ICC 0.740 (0.718, 0.761)). Methods 1 to 6 for evaluating DH in patients with spondylolisthesis had poor inter-rater reliability. The IVD levels with grades IV and V in Pfirrmann scores had significantly lower DH than the IVD levels with grades I to III in Pfirrmann scores. IVD levels with grades IV and V in Pfirrmann scores had significantly higher VAS and ODI than IVD levels with grades I in Pfirrmann scores.

Conclusion

A good-to-excellent intra-rater and inter-rater reliability was achieved on most DH measuring methods on MRI following a standardized and structured protocol. However, small anatomical structures and different tissue borders could influence measurements. Additionally, DH can differentiate between grade IV and V Pfirrmann scores, and severe IVD degeneration (IV and V Pfirrmann) is linked to clinical outcomes.

Comparison of Patient Position and Midline Lumbar Neuraxial Access Via Statistical Model Registration to Ultrasound

Patient positioning and needle puncture site are important for lumbar neuraxial anesthesia. We sought to identify optimal patient positioning and puncture sites with a novel ultrasound registration. We registered a statistical model to volumetric ultrasound data acquired from volunteers (n = 10) in three positions: (i) prone; (ii) seated with thoracic and lumbar flexion; and (iii) seated as in position ii, with a 10° dorsal tilt. We determined injection target size and penetration success by simulating lumbar injections on validated registered models. Injection window and target area sizes in seated positions were significantly larger than those in prone positions by 65% in L2-3 and 130% in L3-4; a 10° tilt had no significant effect on target sizes between seated positions. In agreement with computed tomography studies, simulated L2-3 and L3-4 injections had the highest success at the 50% and 75% midline puncture sites, respectively, measured from superior to inferior spinous process. We conclude that our registration to ultrasound technique is a potential tool for tolerable determination of puncture site success in vivo.

Anatomical differences in the bony structure of L5 and L4: A possible classification according to the lateral tilt of the pedicles

The aim of this study is to underline the necessity of a better knowledge of pedicles anatomy in order to improve surgical treatment of spine disorders such us low back pain, spinal fractures and scholiosis. A classification of pedicles lateral tilt which could help surgeons before the application of screws during transpedicular fixation is reported. Anatomical differences in the orientiation of the pedicles of L5 and L4 have been found. For each patient that met the inclusion criteria underwent: Radiography of the lumbo-sacral region, CT examination, MRI acquisition. Patients were divided into three categories thanks to 3D direct volume rendering of CT scan. Subjects belonged to W-Type, V-Type and U-type depending on their morphometric features. The subdivision was further implemented with measurements of the distance between pedicles and adjacent nervous structures. Concerning L5, W-Type (WT) exhibited a lateral tilt of L5 larger than 36°, V-Type exhibited a lateral tilt of L5 from 30° to 36°, U-type exhibited a lateral tilt of L5 smaller than 30°. Concerning L4, WT exhibited a lateral tilt of 28.4°, VT exhibited a lateral tilt of of 25.1, UT exhibited a lateral tilt of 22.2°; we assume that the degree of lateralization of L4 depends on the one of L5. The way the screw is applied during surgical treatment is clinically relevant, thus our classification may be very useful in order to decrease surgical risk and improve conditions of patients after surgical treatment.

Software-assisted morphometry and volumetry of the lumbar spine

The aim of the study was to measure volumes of the lumbar vertebral bodies with use dedicated Computed Tomography (CT) workstation software to predict expected volume of PMMA for vertebroplasty and supplement calculations using computed tomography scanogram. Quantitative CT scans of 87 women's (mean age 69.4 years; SD 10.9) and 15 men's (mean age 64.3 years; SD 11.8) lumbar spines were analyzed; this made a total of 379 vertebrae. The population of patients was divided into three groups depending on measured BMD value, in accordance with American College of Radiology Practice Parameter for the Performance of Quantitative Computed Tomography (QCT) Bone Densitometry. With the use of the general linear model and least squares means groups were compared regarding vertebral volume, anterior, middle, and posterior vertebral heights. Morphometric parameters tended to be greater in males than in females, in a population of diversified bone mineral density. BMD result should be considered as the modifying factor for preoperative planning of the bone cement volume to be deposited inside the vertebra. Vertebral body volumetry might prove to be a useful tool in pre-operative planning as well as an alternative for treatment monitoring after minimally invasive spinal procedures.

Reliability and validity of a new measurement of lumbar foraminal volume using a computed tomography

PURPOSE

Measuring foraminal stenosis is generally determined by an area calculation. It is difficult to know exactly where it is most appropriate to measure. No precise data are available on a method for calculating the foraminal volume using a CT. To develop a new method for measuring lumbar foraminal volume, we analyzed repeatability and reliability for measuring methods for foraminal volume using CT.

METHODS

The measurements were performed using a CT scan from ten healthy patients, with a mean age of 26.3 years. L3-L4, L4-L5 and L5-S1 foramen were studied, to obtain 60 foraminal measurements. Inter- and intra-observer reproducibility was calculated. Each series was analyzed using the VitreaCore® reconstruction software for volume calculation.

RESULTS

Average volume measurements of 60 foramina and 20 L4-L5 foramina were, respectively, 1.17 and 1.25 mm(3) for observer 1 and 1.21 and 1.29 for observer 2. The intra-observer correlation coefficients for observer 1 when measuring all foramina and L4-L5 foramina were 0.98 and 0.99, respectively. For observer 2, coefficients were 0.90 and 0.92, respectively. The inter-observer correlation coefficients for observer 1 when measuring all foramina and L4-L5 foramina were 0.78 and 0.83, respectively. For observer 2, coefficients were 0.77 and 0.8, respectively. The average differences in intra- and inter-observer measurements regardless of the evaluator group were less than 0.2 mm(3).

CONCLUSIONS

This is the first study measuring lumbar foraminal volume using CT. The excellent reproducibility of this simple measure can supplement a range of foramen measurement tools.

Treatment results in the differential surgery of intradural extramedullary schwannoma of 110 cases

STUDY DESIGN

A retrospective study of intradural extramedullary schwannoma.

OBJECTIVE

The purpose of this study was to compare treatment results in the differential surgery of intradural extramedullary schwannoma.

BACKGROUND

A reference guide to the surgical procedures available to treat intradural extramedullary schwannoma has not yet been established.

METHODS

The study retrospectively reviewed 110 patients: Group A: laminectomy+microscopic excision; Group B: hemilaminectomy+microscopic excision; Group C: laminectomy+microscopic excision+pedicle screw fixation. Researchers selected patients for this retrospective review by applying the following criteria: 1) back pain spread out from the tumor level, sensory and motor loss; 2) treatment by surgery; 3) clinical diagnosis made by physical examination, magnetic resonance imaging (MRI), and pathology; 4) a minimum clinical and radiologic follow-up of 12 months. The clinical outcomes were assessed by comparing the Visual Analogue Pain Scores (VAS) and the Japanese Orthopedic Association Scores (JOA score). The study also performed a cost-effectiveness analysis.

RESULTS

Cervical vertebrae: The estimated blood loss in Group B was significantly less than in Group C (P<0.05) (Table 1). Thoracic vertebrae: The duration of hospital stay and estimated blood loss in Group A was significantly less than in Group C (P<0.05) (Table 2, 3). Lumbar vertebrae: The resection rate in Group C was significantly higher than in Group A and Group B (P<0.05) (Table 4). Treatment in Group B was the least expensive, and therefore, the most cost-effective.

CONCLUSION

In the case of appropriate surgical indications, the study suggests that hemilaminectomy+microscopic excision is advantageous in the removal of cervical schwannoma, and that laminectomy+microscopic excision is advantageous in the removal of thoracic schwannoma; lumbar intradural extramedullary schwannoma can be managed by laminectomy+microscopic excision+pedicle screw fixation.