Diagnostic imaging aspects of Spirocerca lupi infection in the dog

Abstract

This collection of one book chapter and 12 peer reviewed scientific papers comprises of 7 chapters. The first chapter starts with a 2008 review article as an introduction. This was a comprehensive review of Spirocerca lupi with an extensive section on diagnostic imaging, which included the value of computed tomography. The second publication in the first chapter deals with our first paper in 2001 which described in detail the radiographic characteristics of the spondylitis reactions as well as the oesophageal masses, which could be typical or atypical. Aortic aneurysm formation as well as aortic mineralisation visibility was also reported on. Additionally, the value of computed tomography (CT) in spirocercosis was elucidated for the first time. This is the first S. lupi article to extensively describe the imaging findings from a radiological viewpoint and to combine these with the clinical findings. To date this paper is still regularly referenced. The second chapter emphasizes the value of a variety of radiographic techniques, including pneumoesophagography, to optimize the diagnosis of spirocercosis as a primary imaging modality. Radiography remains the cheapest and most readily accessible diagnostic imaging technique and as such making the correct technical decisions, as proven in these 3 papers, optimizes diagnostic capabilities in a cost‐effective way for the first time. The third chapter examines the value of CT and alternative imaging techniques in S. lupi associated disorders to diagnose spirocercosis and its complications. These include the limited value of ultrasonography and the very important role CT, as well as CT angiography, has to play. Computed tomography was shown to play a major role in detecting aortic changes, in decision‐making for surgical removal of neoplastic oesophageal masses, as well as in detecting and determining the extent of secondary changes associated with spirocercosis. The value of CT, first described by us in 2001, is amplified in these publications and has become an essential imaging tool to manage this disease. Magnetic resonance imaging is not available at the Onderstepoort Veterinary Academic Hospital and as such was not addressed in this dissertation. However, its primary use in spirocercosis is in diagnosing aberrant larval migration to the vertebral canal. The fourth chapter discusses the perplexing matter of malignant transformation of the S. lupi associated benign oesophageal nodule and how to diagnose it. This is an on‐going investigation in our department, but this chapter contains the first publication that linked diagnostic imaging findings with clinical parameters in an attempt to determine if malignant transformation of the nodule had taken place. The latter is vitally important in determining prognosis and treatment. Once malignancy is present, metastatic spread can take place to many parts of the body. Two case reports are presented with hitherto undescribed metastatic spread to the central nervous system from the primary oesophageal neoplasm. The fifth chapter looks at the pathomechanisms of spondylitis formation in spirocercosis by means of a radiological‐pathological investigation. This is the first in‐depth veterinary investigation on how vertebral new bone formation takes place and whether inflammation plays a role. The sixth chapter, consisting of a review paper published in 2010, brought together more recent thoughts on some of the dilemmas still facing clinicians in the diagnosis and treatment of spirocercosis. The final chapter concludes with a discussion of the most appropriate imaging procedures to use in diagnosing spirocercosis and its complications. Additionally challenges remaining and future research directions are considered.