Reliability analysis for manual measurement of coronal plane deformity in adolescent scoliosis. Are 30 × 90 cm plain films better than digitized small films?

Abstract

For several years, digitized small radiographs are used to measure Cobb angle in idiopathic scoliosis. The interobserver and intraobserver Cobb angle measurement variability associated with small radiographs were compared with measurement variability associated with the long-cassette radiographs. Twenty adolescent patients with a double major idiopathic scoliosis had erect full-spine p-A radiographs and Cobb angle measurements performed by eight different observers on a 30 · 90 cm plain-film radiograph and a digitized 14 · 42 cm image. Inter-observer and intra-observer reliability using each techniques were assessed using a paired t-test, Spearman rank correlation study and intraclass correlation coefficients. The angle variability between small film and plain-film measurements was assessed using the same methods. Intraobserver and inter-observer study showed good reliability using both techniques. The comparison between small films and plain-films measurements showed very good agreement with an intraclass correlation coefficient of 95% and confidence interval between 0.962 and 0.972. In our study, Cobb angle determination was not found to vary significantly with film size. The small film image used for full-spine radiographs in our institution allows manual Cobb angle measurements to be performed. A study is currently conducted in our institution to determine if a computer-assisted measurement method significantly improves Cobb angle measurements reliability in routine practice compared with manual measurements of Cobb angles on small films.

Intra- and inter-observer reliability of determining radiographic sagittal parameters of the spine and pelvis using a manual and a computer-assisted methods

“…The difficulty of reliably measuring anterior-posterior (AP) scoliosis radiographs by experienced spinal surgeons using the manual Cobb technique for the classification of scoliosis has already been established [3,4,17,20]. Recently, a computerized digital measurement technique for scoliosis demonstrated improved precision and good correlation with manually measured radiographs validating this methodology for the measurement of the spine in the coronal plane [12].…”

Variability of Manual and Computerized Methods for Measuring Coronal Vertebral Inclination in Computed Tomography Images

“…Such measurements are biased by the selection of the most tilted endplates, errors in drawing lines and systematic errors of inaccurate measuring devices (Capasso et al, 1992). As a result, the reported intra-observer SD between 1.5 • and 8.5 • , and inter-observer SD between 2.5 • and 8.8 • (Chen et al, 2007;Jeffries et al, 1980;Oda et al, 1982;Goldberg et al, 1988;Dutton et al, 1989;Ylikoski and Tallroth, 1990;Carman et al, 1990;Pruijs et al, 1994;Loder et al, 1995;Diab et al, 1995;Shea et al, 1998;Facanha-Filho et al, 2001;Loder et al, 2004;Wills et al, 2007;Gstoettner et al, 2007;De Carvalho et al, 2007;Tanure et al, 2010) span across a relatively large range of values. Adam et al (2005) evaluated the Cobb angle in CT images by extracting reformatted cross-sections, resulting in intra-and inter-observer variability of 3.4 • and 2.7 • SD, respectively.…”

Variability in Flexion Extension Radiographs of the Lumbar Spine: A Comparison of Uncontrolled and Controlled Bending

“…Manual measurements are performed by sketching lines or superimposing a measurement grid on physical films on a light board or computer based system. 6,7 Computerassisted manual measurements are performed by using software to manually construct lines between vertebral landmarks and utilizing the computer software to provide measurement data. 8,9,10 Automated (semi) computerized measurements are performed in digital radiographs by computer software applying image processing.…”