Comparison of imaging techniques to detect migrating foreign bodies. Relevance of preoperative and intraoperative ultrasonography for diagnosis and surgical removal

Abstract

Objective: To report the relative sensitivity of different diagnostic imaging (DI) techniques to detect migrating foreign bodies (FB) in subcutaneous and underlying soft tissue structures of dogs and evaluate the value of intraoperative ultrasonography (intraop-US).Study design: Retrospective study. Sample population: Forty-one dogs.Methods: Medical records (2007-2019) of dogs that underwent surgery for a chronic abscess or draining tract were included when preoperative US (preop-US), computed tomography (preop-CT), or preop-MRI, and at least 6 months of follow-up information were available. Collected data included the DI techniques used, DI findings, and surgical findings. The relative sensitivity of each preoperative DI (preop-DI) technique was calculated. Dogs were divided into two groups, dogs that underwent only a preop-DI examination (group A) and dogs that underwent an additional intraop-US (group B). The success rates for FB surgical removal were compared between groups. Results: The relative sensitivity of preop-US and preop-CT/MRI was 88% (95% CI, 70%-95.8%) and 57.1% (95% CI, 32.6%-78.6%), respectively. The success rate for FB removal was higher in group B (89.5%) than in group A (59.1%; P = .038). Clinical resolution occurred in 90.2% of dogs for a median duration of follow-up of 4.2 years (6 months to 9.3 years). Conclusion: Preoperative US seems more suitable than preop-CT/MRI for detection of migrating FB in subcutaneous and underlying soft tissue structures. The use of intraop-US increases the success rate for FB surgical removal.Clinical significance: Intraoperative US should be used in combination with preop-US to increase the likelihood of migrating FB surgical removal in dogs.

Infected parotid sialocele treated by vegetal foreign body removal in a dog

“…Acoustic shadowing was not always associated with vegetal foreign body, making the detection more difficult. 17 The sensitivity of ultrasound may also have played a role: the sensitivity of ultrasound to detect migrating foreign bodies in dogs varies from 82% to 88%. 16,17 In this case, CT also failed to visualise the foreign body.…”

“…This may be because the terminal part of the duct was not assessed directly in the oral cavity and due to the small size of the foreign bodies. Acoustic shadowing was not always associated with vegetal foreign body, making the detection more difficult 17 . The sensitivity of ultrasound may also have played a role: the sensitivity of ultrasound to detect migrating foreign bodies in dogs varies from 82% to 88% 16,17 .…”

“…17 The sensitivity of ultrasound may also have played a role: the sensitivity of ultrasound to detect migrating foreign bodies in dogs varies from 82% to 88%. 16,17 In this case, CT also failed to visualise the foreign body. The sensitivity of CT to identify migrating foreign bodies has been reported to be up to 75%.…”

Preoperative computed tomography, surgical treatment and long‐term outcomes of dogs with abscesses on migrating vegetal foreign bodies and oropharyngeal stick injuries: 39 cases (2010‐2021)

“…Cases were considered "true positives" when VFB were found at surgery. Positive and negative predictive values were determined on the basis of review of CT images with knowledge of the surgical findings, as reported in a former study (Blondel et al 2021). The relative sensitivity and specificity of CT in detecting VFB were calculated according to the number of true positive cases that were correctly diagnosed preoperatively.…”

“…The use of imaging modalities for VFB identification may thus be critical. To facilitate and guide surgical approaches, preoperative imaging using ultrasound (US), CT or magnetic resonance imaging (MRI) have been described for surgical planning when abscesses are suspected to result from VFB and/or OSI (White & Lane 1988, Armbrust et al 2003, Dobromylskyj et al 2008, Nicholson et al 2008, Birettoni et al 2017, Blondel et al 2021, thus increasing the chances of finding VFB during surgery and decreasing the risk of recurrence (Blondel et al 2021, Jacques et al 2022. The purpose of preoperative diagnostic imaging is manifold.…”