Diagnostic Imaging of the Abdomen: US, CT, MRI. Which Evidence?

With the ongoing development of specialisation the concept of Evidence-Based Medicine (EBM) has found its way into the range of disciplines of veterinary medicine. EBM is fundamental for establishing the best veterinary practices. The EBM triad integrates „best research evidence with clinical expertise and patient values“ (Sackett et al. 2000) and is an effective method for finding and critically appraising an appropriate diagnostic test.

Practicing evidence in imaging diagnostics always begins with the definition of a specific clinical question integrating patient data, planned intervention and comparison with alternative methods.

For traditional abdominal imaging methods such as radiography and grey scale ultrasound a comprehensive body of evidence on imaging technique and possible findings exists for many clinical questions in the available literature. Especially with regard to emergency situations in traumatized animals or patients with an acute abdomen ultrasound (US) remains a quick and accurate triage instrument – even in the hands of non-experienced operators (Lisciandro 2011). However, for the assessment of changes within parenchymatous organs such as the liver, kidneys or spleen conventional US remains a sensitive but non-specific test. In most instances, there is a lack of association between US findings and histologic diagnosis (Warren-Smith et al. 2012). A highly promising advancement is contrast enhanced ultrasound (CEUS). Recent research demonstrated CEUS to be a highly sensitive and specific tool with an overall accuracy of 97-100% to determine the malignancy of focal liver lesions (O’Brien et al. 2004, Ivancic et al. 2009). Although this high accuracy has not been proven to be the same for splenic lesions in general (Ohlerth et al. 2008, Rossi et al. 2008, Ivancic et al. 2009) specific morphologic features such as tortuous tumor feeding vessel seem to be associated with focal splenic malignancies (Taeymans & Penninck 2011). CEUS is useful in any situation where the perfusion of organs or lesions is of special interest. Many previous studies were focused on documentation of normal perfusion patterns of the abdominal organs. Further research concerning many clinical questions is being established at present. The future of CEUS is likely to provide solutions not only for diagnostic applications but also for therapeutic options such as targeted drug delivery directed by US induced acoustic emission.  [...]