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Abstract

OBJECTIVE To characterize CT findings in dogs with a presumptive diagnosis of chronic bronchitis, estimate the accuracy of thoracic CT for the diagnosis of chronic bronchitis in dogs, and determine interobserver agreement for this method.

DESIGN Retrospective case-control and cross-sectional study.

ANIMALS 26 dogs with confirmed chronic bronchitis and 20 control dogs with unremarkable results of thoracic CT and no recorded history of cough.

PROCEDURES Thoracic CT images of all dogs were interpreted for signs of chronic bronchitis by 2 observers who used specific criteria; observers also used the images to compute the bronchial wall thickness-to-pulmonary artery diameter (BWPA) ratio of the cranial lung lobes. Interobserver agreement was assessed for both diagnostic approaches. Performance of thoracic CT and the BWPA ratio specifically in the diagnosis of chronic bronchitis were evaluated, with the final diagnosis made by the attending internist as the reference standard. Associations between independent variables and the BWPA ratio for all dogs were assessed by linear regression.

RESULTS Accuracy of thoracic CT examination for the diagnosis of chronic bronchitis was 57%, sensitivity was 46%, and specificity was 90%. Interobserver agreement was moderate (κ = 0.50). The BWPA ratio had poor accuracy for discriminating dogs with chronic bronchitis from control dogs. Linear regression revealed that as dog body weight increased, BWPA ratios for the left and right cranial lung lobes decreased slightly but significantly.

CONCLUSIONS AND CLINICAL RELEVANCE These results suggested that thoracic CT and the associated BWPA ratio have limited value in the diagnosis of chronic bronchitis in dogs.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate effects of imaging plane, flexion and extension, patient weight, and observer on computed tomographic (CT) image measurements of the area of the lumbosacral (L7-S1) intervertebral foramen (LSIF) in dogs.

Sample—12 dog cadavers (2 were excluded because of foraminal stenosis).

Procedures—In each cadaver, sagittal, sagittal oblique, transverse oblique, and double oblique CT images were obtained at 3 zones (entrance, middle, and exit zones) of the region of the lateral lumbar spinal canal that comprises the LSIF while the lumbosacral junction (LSJ) was positioned in flexion or extension. Barium-impregnated polymethylmethacrylate was used to fill the intervertebral foramina to aid boundary detection. Measurements of interest were obtained.

Results—Among the dog cadavers, there was large variability in LSIF cross-sectional areas (range, 0.12 to 0.44 cm2; SD, 0.1 cm2) and in foraminal angles required to obtain a double oblique plane in LSJ extension (SD, 8° to 9°). For LSIF area measurements in standard sagittal CT images, interobserver variability was 23% to 44% and intraobserver variability was 4% to 5%. Sagittal oblique images obtained during LSJ extension yielded smaller mean LSIF areas (0.30 cm2), compared with findings in sagittal images (0.37 to 0.52 cm2). The exit and middle zone areas were smaller than the entrance zone area in sagittal images obtained during LSJ extension.

Conclusions and Clinical Relevance—Repeated measurements of the LSIF area in images obtained during LSJ extension may be unreliable as a result of interobserver variability and the effects of dog positioning and CT slice orientation.

Full access
in American Journal of Veterinary Research