Comparison of Thoracic Ultrasonography and Radiography for the Detection of Induced Small Volume Pneumothorax in the Horse

Abstract

Small volume pneumothorax can be challenging to diagnose in horses. The current standard method for diagnosis is standing thoracic radiography. We hypothesized that thoracic ultrasonography would be more sensitive. Objectives of this prospective, experimental study were to describe a thoracic ultrasound method for detection of small volume pneumothorax in horses and to compare results of radiography and ultrasound in a sample of horses with induced small volume pneumothorax. Six mature healthy horses were recruited for this study. For each horse, five 50 ml air boluses were sequentially introduced via a teat cannula into the pleural space. Lateral thoracic radiographs and standardized ultrasound (2D and M-mode) examinations of both hemithoraces were performed following administration of each 50 ml air bolus. Radiographs and ultrasound images/videos were analyzed for detection of pneumothorax by four independent investigators who were unaware of treatment status. Sensitivity, specificity, positive predictive values, negative predictive values, and agreement among investigators (Kappa test, κ) were calculated for radiography, 2D and M-mode ultrasound. Comparisons were made using a chi-squared exact test with significance set at P < 0.05. Two-dimensional (84%) and M-mode (80%) ultrasound were more sensitive than radiography (48%) for pneumothorax detection (P = 0.02 and P = 0.04, respectively). Specificity and positive predictive values were similar for all three imaging modalities (P = 1). Agreement between investigators for pneumothorax detection was excellent for 2D ultrasound (κ = 1), very good for M-mode ultrasound (κ = 0.87), and good for radiography (κ = 0.79). Findings from this experimental study supported the use of thoracic ultrasonography as a diagnostic method for detecting pneumothorax in horses.

Comparison of thoracic ultrasonography and thoracic radiography between healthy adult horses and horses with bacterial pneumonia using a novel, objective ultrasonographic scoring system

“…The only direct comparison to date between thoracic radiography and ultrasonography in adult horses evaluated 6 horses in which small-volume pneumothorax was experimentally induced. In that study, the diagnostic sensitivity of M-mode (84%) and 2D-mode (80%) TUS was significantly higher ( p = 0.02 and 0.04, respectively) than thoracic radiography (48%) ( 8 ).…”

“…Thoracic ultrasonography in human and small animal medicine is comparable in sensitivity to radiography and computed tomography (CT) for the diagnosis of pneumonia, pulmonary edema, pneumothorax and pulmonary contusions (2)(3)(4)(5)(6). While there have been direct comparisons between the sensitivity of TUS and radiography in the identification of Rhodococcus equi pneumonia in foals and pneumothorax in the adult horse, the two modalities have not been compared for their diagnostic accuracy in bacterial pneumonia in adult horse (7,8).…”

Pneumoperitoneum as an uncommon complication after an axillary laceration in a horse

“…In humans, the most common diagnostic modalities for detecting pneumothorax and pneumoperitoneum are ultrasound and radiography (Boy & Sweeney, 2000;Kim et al, 2014). An experimental study by Partlow et al (2017) found that ultrasound (2D and M-mode) is more sensitive than radiography for the detection of small volume induced-pneumothorax in horses.…”

“…An experimental study by Partlow et al. ( 2017 ) found that ultrasound (2D and M‐mode) is more sensitive than radiography for the detection of small volume induced‐pneumothorax in horses.…”

Highlights of recent clinically relevant papers

“…In this prospective, experimental study Jessica Partlow and colleagues compared the results of thoracic ultrasonography and radiography for the detection of induced small volume pneumothorax .…”