Interobserver agreement in interpreting radiographs of horses using the german Radiology-Guidelines 2007 ("Röntgenleitfaden 2007")

Comparison of ultrasonographic and computed tomographic imaging of equine thoracolumbar articular process joints

BACKGROUND

Osteoarthritis of the equine thoracolumbar articular process joints (APJs) has been linked to back pain. Changes are commonly diagnosed through nuclear scintigraphy, radiography and ultrasonography (US).

OBJECTIVES

(1) To assess the agreement of APJ grades between US and computed tomography (CT) images; (2) to assess the effect of location on the agreement of APJ grades between US and CT images. It was hypothesised that: (1) Periarticular modelling and modification of the joint space would have the highest and lowest agreement between US and CT images, respectively; (2) Caudal thoracolumbar APJ grades would have higher agreement between US and CT images than mid thoracic APJs.

STUDY DESIGN

Comparative diagnostic imaging study using cadaveric specimens.

METHODS

Disarticulated thoracolumbar spines of six equids euthanised for reasons unrelated to back pain, underwent US and CT examination of the APJs. Images were assessed for periarticular modelling, modification of the joint space and enlargement of the APJ. Intra-observer, inter-modality and inter-observer agreement using multilevel weighted kappa statistics to evaluate the effects of location, US/CT characteristic and their interaction.

RESULTS

Intra-observer agreement of US and CT grades ranged from moderate to perfect. Between T15 and L1, inter-modality agreement (CT vs. US) for periarticular modelling was moderate, and fair for enlargement and modification of the joint space. Inter-observer agreement (US vs. US) of periarticular modelling was substantial between T15 and L1, moderate between L1 and L5 and fair between T10 and T15. Wide confidence intervals (CIs) seen for most grades apart from inter-observer grades of periarticular modelling at T15-L5, introducing a degree of uncertainty into the results.

MAIN LIMITATIONS

Large prevalence index influenced kappa values, small sample size.

CONCLUSIONS

Good inter-observer (US vs. US) and inter-modality (CT vs. US) agreement of caudal thoracolumbar APJ periarticular modelling. This US characteristic provides a measure of bone change, therefore supporting the use of diagnostic ultrasound. Inter-modality CIs were wide, highlighting the study and imaging modality limitations.

Inter- and intra-observer agreement for grading radiographs of thoracolumbar spinous processes in healthy horses during a pre-purchase examination

BACKGROUND

There is wide variability in radiographic grading systems in thoracolumbar spinous processes in horses. The aim of this study was to determine the agreement of grading different parameters, and combinations of those, in radiographs of the spinous processes of the equine thoracolumbar spine in the scope of a pre-purchase examination. We hypothesized that agreement is variable and interpretation of these radiographs is difficult.

METHODS

Radiographs of the thoracolumbar spine of healthy horses (N = 100) were assessed by three observers. Spinous processes were separately graded for interspinous space width, modelling, radiopacities, radiolucencies and isolated opacities dorsally. Inter- and intra-observer agreement was assessed for individual and combinations of parameters.

RESULTS

Agreement (inter- and intra-observer) was good for the following parameters: interspinous space width, isolated opacities dorsally, beak-shaped formations craniodorsally and modelling cranioventrally. The agreement increased slightly for a sum of specific parameters such as radiopacities, modelling, dorsal abnormalities and related abnormalities involving increased opacity, modelling and osseous cyst-like lesions. Agreement for the total radiographic abnormalities per back was moderate.

CONCLUSIONS

Grading of thoracolumbar radiographs in horses without back pain showed good inter- and intra-observer agreement for specific parameters and these should be used in future grading of spinous processes. Limitations should be considered in pre-purchase examinations.