Limits...
Measurement of vertebral rotation in adolescent idiopathic scoliosis with low-dose CT in prone position - method description and reliability analysis.

Abul-Kasim K, Karlsson MK, Hasserius R, Ohlin A - Scoliosis (2010)

Bottom Line: This study has shown that measurements of vertebral rotation in prone position were more reliable on axial CT images than on CT scanogram.The measurement of vertebral rotation on CT (corrected to the pelvic tilt) in prone position imposes lower impact of the recumbent position on the vertebral rotation than did MRI in supine position.However, the magnitude of differences is of doubtful clinical significance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Medicine, Lund University, Division of Neuroradiology, Diagnostic Centre for Imaging and Functional Medicine, Skåne University Hospital, 20502 Malmö, Sweden. kasim.abul-kasim@med.lu.se.

ABSTRACT

Background: To our knowledge there is no report in the literature on measurements of vertebral rotation with low-dose computed tomography (CT) in prone position.

Aims: To describe and test the reliability of this new method, compare it with other methods in use and evaluate the influence of body position on the degree of vertebral rotation measured by different radiological methods.

Study design: Retrospective study.

Methods: 25 consecutive patients with adolescent idiopathic scoliosis scheduled for surgery (17 girls, 8 boys) aged 15 +/- 2 years (mean +/- SD) were included in the analysis of this study. The degree of the vertebral rotation was in all patients measured according to the method of Perdriolle on standing plain radiographs and on supine CT scanogram, and according to the method of Aaro and Dahlborn on axial CT images in prone position and on magnetic resonance imaging (MRI) in supine position. The measurements were done by one neuroradiologist at two different occasions. Bland and Altman statistical approach was used in the reliability assessment.

Results: The reliability of measuring vertebral rotation by axial CT images in prone position was almost perfect with an intraclass correlation coefficient of 0.95, a random error of the intraobserver differences of 2.3 degrees , a repeatability coefficient of 3.2 degrees and a coefficient of variation of 18.4%. Corresponding values for measurements on CT scanogram were 0.83, 5.1 degrees , 7.2 degrees , and 32.8%, respectively, indicating lower reliability of the latter modality and method. The degree of vertebral rotation measured on standing plain radiographs, prone CT scanogram, axial images on CT in prone position and on MRI in supine position were 25.7 +/- 9.8 degrees , 21.9 +/- 8.3 degrees , 17.4 +/- 7.1 degrees , and 16.1 +/- 6.5 degrees , respectively. The vertebral rotation measured on axial CT images in prone position was in average 7.5% larger than that measured on axial MRI in supine position.

Conclusions: This study has shown that measurements of vertebral rotation in prone position were more reliable on axial CT images than on CT scanogram. The measurement of vertebral rotation on CT (corrected to the pelvic tilt) in prone position imposes lower impact of the recumbent position on the vertebral rotation than did MRI in supine position. However, the magnitude of differences is of doubtful clinical significance.

No MeSH data available.


Related in: MedlinePlus

CT with low radiation dose performed in prone position. Axial images at the level of L2 (A and C), and at the level of T6 (B and D). (E-F) Axial images at the level of the femoral heads for the measurements of pelvic tilt. To obtain the corrected value of vertebral rotation, the degree of the pelvic tilt was subtracted from the measured degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the same direction (A/E and D/F). On the other hand, the degree of the pelvic tilt was added to the degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the different directions (B/E and C/F). Thus the corrected degree of vertebral rotation will be: A-E for example A, B+E in example B, C+F for example C, and D-F in example D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC2837618&req=5

Figure 2: CT with low radiation dose performed in prone position. Axial images at the level of L2 (A and C), and at the level of T6 (B and D). (E-F) Axial images at the level of the femoral heads for the measurements of pelvic tilt. To obtain the corrected value of vertebral rotation, the degree of the pelvic tilt was subtracted from the measured degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the same direction (A/E and D/F). On the other hand, the degree of the pelvic tilt was added to the degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the different directions (B/E and C/F). Thus the corrected degree of vertebral rotation will be: A-E for example A, B+E in example B, C+F for example C, and D-F in example D.

Mentions: (3) CT in prone position for the measurement of vertebral rotation according to the method of Aaro and Dahlborn [9]: Axial 3 mm thick slices with skeletal algorithm and skeletal window were used for this purpose. The vertebral rotation was measured at the apical vertebra of the major structural curve and corrected to the pelvic tilt (Figure 2A-F).


Measurement of vertebral rotation in adolescent idiopathic scoliosis with low-dose CT in prone position - method description and reliability analysis.

Abul-Kasim K, Karlsson MK, Hasserius R, Ohlin A - Scoliosis (2010)

CT with low radiation dose performed in prone position. Axial images at the level of L2 (A and C), and at the level of T6 (B and D). (E-F) Axial images at the level of the femoral heads for the measurements of pelvic tilt. To obtain the corrected value of vertebral rotation, the degree of the pelvic tilt was subtracted from the measured degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the same direction (A/E and D/F). On the other hand, the degree of the pelvic tilt was added to the degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the different directions (B/E and C/F). Thus the corrected degree of vertebral rotation will be: A-E for example A, B+E in example B, C+F for example C, and D-F in example D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2837618&req=5

Figure 2: CT with low radiation dose performed in prone position. Axial images at the level of L2 (A and C), and at the level of T6 (B and D). (E-F) Axial images at the level of the femoral heads for the measurements of pelvic tilt. To obtain the corrected value of vertebral rotation, the degree of the pelvic tilt was subtracted from the measured degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the same direction (A/E and D/F). On the other hand, the degree of the pelvic tilt was added to the degree of the rotation of the vertebral body when the vertebral body and the pelvis were tilted at the different directions (B/E and C/F). Thus the corrected degree of vertebral rotation will be: A-E for example A, B+E in example B, C+F for example C, and D-F in example D.
Mentions: (3) CT in prone position for the measurement of vertebral rotation according to the method of Aaro and Dahlborn [9]: Axial 3 mm thick slices with skeletal algorithm and skeletal window were used for this purpose. The vertebral rotation was measured at the apical vertebra of the major structural curve and corrected to the pelvic tilt (Figure 2A-F).

Bottom Line: This study has shown that measurements of vertebral rotation in prone position were more reliable on axial CT images than on CT scanogram.The measurement of vertebral rotation on CT (corrected to the pelvic tilt) in prone position imposes lower impact of the recumbent position on the vertebral rotation than did MRI in supine position.However, the magnitude of differences is of doubtful clinical significance.

View Article: PubMed Central - HTML - PubMed

Affiliation: Faculty of Medicine, Lund University, Division of Neuroradiology, Diagnostic Centre for Imaging and Functional Medicine, Skåne University Hospital, 20502 Malmö, Sweden. kasim.abul-kasim@med.lu.se.

ABSTRACT

Background: To our knowledge there is no report in the literature on measurements of vertebral rotation with low-dose computed tomography (CT) in prone position.

Aims: To describe and test the reliability of this new method, compare it with other methods in use and evaluate the influence of body position on the degree of vertebral rotation measured by different radiological methods.

Study design: Retrospective study.

Methods: 25 consecutive patients with adolescent idiopathic scoliosis scheduled for surgery (17 girls, 8 boys) aged 15 +/- 2 years (mean +/- SD) were included in the analysis of this study. The degree of the vertebral rotation was in all patients measured according to the method of Perdriolle on standing plain radiographs and on supine CT scanogram, and according to the method of Aaro and Dahlborn on axial CT images in prone position and on magnetic resonance imaging (MRI) in supine position. The measurements were done by one neuroradiologist at two different occasions. Bland and Altman statistical approach was used in the reliability assessment.

Results: The reliability of measuring vertebral rotation by axial CT images in prone position was almost perfect with an intraclass correlation coefficient of 0.95, a random error of the intraobserver differences of 2.3 degrees , a repeatability coefficient of 3.2 degrees and a coefficient of variation of 18.4%. Corresponding values for measurements on CT scanogram were 0.83, 5.1 degrees , 7.2 degrees , and 32.8%, respectively, indicating lower reliability of the latter modality and method. The degree of vertebral rotation measured on standing plain radiographs, prone CT scanogram, axial images on CT in prone position and on MRI in supine position were 25.7 +/- 9.8 degrees , 21.9 +/- 8.3 degrees , 17.4 +/- 7.1 degrees , and 16.1 +/- 6.5 degrees , respectively. The vertebral rotation measured on axial CT images in prone position was in average 7.5% larger than that measured on axial MRI in supine position.

Conclusions: This study has shown that measurements of vertebral rotation in prone position were more reliable on axial CT images than on CT scanogram. The measurement of vertebral rotation on CT (corrected to the pelvic tilt) in prone position imposes lower impact of the recumbent position on the vertebral rotation than did MRI in supine position. However, the magnitude of differences is of doubtful clinical significance.

No MeSH data available.


Related in: MedlinePlus