Reliability of cervical lordosis measurement techniques on long-cassette radiographs.

PURPOSE: Lateral radiographs are commonly used to assess cervical sagittal alignment. Three assessment methods have been described and are commonly utilized in clinical practice. These methods are described for perfect lateral cervical radiographs, however in everyday practice radiograph quality varies. The aim of this study was to compare the reliability and reproducibility of 3 cervical lordosis (CL) measurement methods. METHODS: Forty-four standing lateral radiographs were randomly chosen from a lateral long-cassette radiograph database. Measurements of CL were performed with: Cobb method C2-C7 (CM), C2-C7 posterior tangent method (PTM), sum of posterior tangent method for each segment (SPTM). Three independent orthopaedic surgeons measured CL using the three methods on 44 lateral radiographs. One researcher used the three methods to measured CL three times at 4-week time intervals. Agreement between the methods as well as their intra- and interobserver reliability were tested and quantified by intraclass correlation coefficient (ICC) and median error for a single measurement (SEM). ICC of 0.75 or more reflected an excellent agreement/reliability. The results were compared with repeated ANOVA test, with p < 0.05 considered as significant. RESULTS: All methods revealed excellent intra- and interobserver reliability. Agreement (ICC, SEM) between three methods was (0.89°, 3.44°), between CM and SPTM was (0.82°, 4.42°), between CM and PTM was (0.80°, 4.80°) and between PTM and SPTM was (0.99°, 1.10°). Mean values CL for a CM, PTM, SPTM were 10.5° ± 13.9°, 17.5° ± 15.6° and 17.7° ± 15.9° (p < 0.0001), respectively. The significant difference was between CM vs PTM (p < 0.0001) and CM vs SPTM (p < 0.0001), but not between PTM vs SPTM (p > 0.05). CONCLUSIONS: All three methods appeared to be highly reliable. Although, high agreement between all measurement methods was shown, we do not recommend using Cobb measurement method interchangeably with PTM or SPTM within a single study as this could lead to error, whereas, such a comparison between tangent methods can be considered.

A systematic procedure to optimise dose and image quality for the measurement of inter-vertebral angles from lateral spinal projections using Cobb and superimposition methods.

BACKGROUND: Patients with vertebral column deformations are exposed to high risks associated with ionising radiation exposure. Risks are further increased due to the serial X-ray images that are needed to measure and asses their spinal deformation using Cobb or superimposition methods. Therefore, optimising such X-ray practice, via reducing dose whilst maintaining image quality, is a necessity. OBJECTIVES: With a specific focus on lateral thoraco-lumbar images for Cobb and superimposition measurements, this paper outlines a systematic procedure to the optimisation of X-ray practice. METHODS: Optimisation was conducted based on suitable image quality from minimal dose. Image quality was appraised using a visual-analogue-rating-scale, and Monte-Carlo modelling was used for dose estimation. The optimised X-ray practice was identified by imaging healthy normal-weight male adult living human volunteers. RESULTS: The optimised practice consisted of: anode towards the head, broad focus, no OID or grid, 80 kVp, 32 mAs and 130 cm SID. CONCLUSION: Images of suitable quality for laterally assessing spinal conditions using Cobb or superimposition measurements were produced from an effective dose of 0.05 mSv, which is 83% less than the average effective dose used in the UK for lateral thoracic/lumbar exposures. This optimisation procedure can be adopted and use for optimisation of other radiographic techniques.

Accuracy of photogrammetry for detecting adolescent idiopathic scoliosis progression.

BACKGROUND: The gold standard method of monitoring the evolution of scoliosis has been serial standing, posteroanterior, full-length spine radiographs with curvature measurements using the Cobb method. However, over the course of follow-up, patients can receive high radiation doses. Various studies have shown that repeated exposure to radiation in children and adolescents can be harmful to their health. PURPOSE: To determine the accuracy of photogrammetry in evaluating the progression of adolescent idiopathic scoliosis in comparison with radiography. STUDY DESIGN: Diagnostic study. PATIENT SAMPLE: Ninety adolescents subjected to radiographic follow-up of idiopathic scoliosis. OUTCOME MEASURES: The angle of scoliotic curvature was measured using the Cobb radiographic method and photogrammetry. An increase of 5° or more between two radiographic exams was considered a progression of the curvature and was defined as the standard for calculations of sensitivity, specificity, predictive value, and accuracy of the photogrammetric method for measuring scoliosis progression. METHODS: Patients were subjected to radiographic and photogrammetric exams concomitantly and were reevaluated after an average of 8.6 months. The exams were analyzed separately and independently by two examiners for progression of scoliosis. RESULTS: The measurements of the curves at the beginning of the study were 39.5±16.7° and 39.5±14.3° for radiographic and photogrammetric exams, respectively (p=1.0). At the end of the study, the measurements of the curves were 40.2±16.2° and 41.3±15.1° for the radiographic and photogrammetric exams, respectively (p=.310). The photogrammetric method had an accuracy of 89% (Confidence interval [CI] 95%=82.5-95.5) for the detection of scoliosis progression, with a sensitivity of 94.4% (CI 95%=89.6-99.2), a specificity of 86.7% (CI 95%=79.7-93.7), a positive predictive value of 75.5% (CI 95%=66.6-84.4), a negative predictive value of 97.2% (CI 95%=93.8-100), and a Kappa index of 0.75 (CI 95%=66.1-83.9). The interclass correlation coefficient between the two methods was 0.74 (CI 95%=0.65-0.81; p=0). CONCLUSIONS: The photogrammetric method showed good performance for detecting the progression of adolescent idiopathic scoliosis in comparison with the radiographic exam method.

Thoracic Kyphosis is Now Uncommon Amongst Children and Adolescents with Cystic Fibrosis.

Historically, thoracic kyphosis has been reported to be common amongst patients with cystic fibrosis (CF). The mechanisms leading to the development of this abnormality of the chest wall are not fully understood. In order to explore the prevalence of the condition amongst children with CF in the early twenty-first century and to explore factors that might be contributing to its development, a retrospective cross sectional study was undertaken in a regional CF unit. Data were obtained from 74 children with CF aged 8-16 years attending for their annual review. Thoracic kyphosis was measured from lateral chest X-ray using an alternative Cobb method. Lung function, disease severity, and nutritional status were also recorded. Correlations between measures were explored using a multiple linear regression model. The range of Cobb angles measured was 5.4-44.3° with thoracic kyphosis identified in only two subjects. There was no correlation between age and thoracic kyphosis, however, there was a significant correlation between lung function and thoracic kyphosis (p = 0.004). Regression coefficient (b) was -0.26 (95% CI: -0.44, -0.08). The prevalence of thoracic kyphosis is significantly less amongst children with CF than previously reported. This appears likely to be associated with the overall improvements in pulmonary status. Studies of older populations may bring further understanding of increasing thoracic kyphosis in people with CF.

Kyphotic Angle Measurement Accuracy for Vertebral Osteoporotic Compression Fracture: Reliable Method for Kyphotic Angle Measurement

OBJECTIVE: Having a reliable and reproducible measurement technique to measure the sagittal contour in vertebral fractures is paramount to clinical decision making. This study is designed to determine the most reliable measurement technique in osteoporotic vertebral compression fracture. METHODS: Fifteen lateral radiographs of thoracic and lumbar fractures were selected and measured on two separate occasions by three spine surgeons using six different measurement techniques (Centroid, Harrison Posterior Tangent Methods and 4 different types of modified Cobb method). The radiograph quality was assessed and the center beam location was determined. Statistical analysis including ANOVA for repeated measures was carried out using the SAS software (v 8.0). RESULTS: The inter and intraobserver variance of the Cobb method 4 and Harrison posterior tangent method were significantly lower than the other four methods. The intraobserver correlation coefficients were the most consistent using the Cobb method 4 (0.982), which was followed by the Harrison posterior tangent (0.953) and Cobb methods 1 (0.874). The intraobserver agreement (% of repeated measures within 5 degrees of the original measurement) ranged from 42% to 98% for each technique for all three observers, with the Cobb method 4 showing the best agreement (97.8%) followed by the Harrison posterior tangentmethod (93.7%). CONCLUSION: The Cobb method-4 and Harrison posterior tangent methods, when applied to measuring the kyphosis, are reliable and have a similar small error range. The Cobb method 4 shows the best overall reliability. However, the centroid method and Cobb method using a fractured endplate do not produce an accurate result due to inter and intraobserver differences in determining the baseline.