Radiography, computed tomography (CT), ultrasound, and endoscopy are all common, diagnostic imaging techniques in mammalian medicine. Slight alterations in their usage confer benefits when imaging poikilothermic aquatic organisms. With the increased detail of CR and DR digital radiology, fish and invertebrates with total lengths of 6–10 cm are now evaluated effectively.2,4,5 Swim bladder disease is one of the more common, confounding diseases with teleosts. When the fish's anatomy allows it, fluid lines in the swim bladder lumen are best diagnosed radiographically in standing lateral view. Radiography can be used to guide aspirations as a form of interventional radiology in these cases. Spinal disease is common among teleosts and elasmobranchs. Ante and post mortem radiography can be instrumental in evaluating spinal disease related to age, trauma, nutrition and disease.
CT's increased availability and rapid imaging has increased its use among poikilotherms. 3-D reconstructions of CT scans show the complexity of unusual swim bladders in Atlantic spadefish (Chaetodipterus faber) and red drum (Sciaenops ocellatus). The slow speed of magnetic resonance imaging (MRI) has limited its diagnostic potential, but research studies have found it invaluable.3,6 As the technology improves, MRI will become far more useful. A study on Chaetodipterus faber using digital radiography, CT and MRI will demonstrated.
Endoscopy has a number of uses in fish and invertebrates, including non-invasive examination of gills and minimally invasive visualization/biopsy in the coelom.1,5 Gill biopsies evaluate a small fraction of the entire gill surface while endoscopy can be far more comprehensive in assessing gill health. In sea turtles, endoscopy is often the best diagnostic when CT is either unavailable or unrewarding. Endoscopes can also act as direct therapeutic devices which will be demonstrated in treating impactions in marine turtles.
Lastly, ultrasonography is actually enhanced in aquatic patients when they are evaluated in the water. Either through training, restraint or sedation, the aquatic environment actually benefits ultrasound image quality.
1. Boone SS, et al. Comparison between coelioscopy and coeliotomy for liver biopsy in channel catfish. Journal of the American Veterinary Medical Association. 2008;233(6):960–967.
2. Smith SA, Smith BJ. Xeroradiographic and radiographic anatomy of the channel catfish, Ictalurus punctatus. Veterinary Radiology & Ultrasound. 1994;35(5):384–390.
3. Blackban SJ, Stoskopf MK. In vivo nuclear magnetic resonance imaging and spectroscopy of aquatic organisms. Magnetic Resonance Imaging. 1990;8(2):191–198.
4. Spotswood T, Smith SA. Cardiovascular and gastrointestinal radiographic contrast studies in the horseshoe crab (Limulus polyphemus). Veterinary Radiology & Ultrasound. 2007;48(1):14–20.
5. Nollens HH, Schofield JC, Keogh JA, Probert PK. Evaluation of radiography, ultrasonography and endoscopy for detection of shell lesions in live abalone Haliotis iris (Mollusca: Gastropoda). Diseases of Aquatic Organisms. 2002;50(2):145-152.
6. Ziegler A, Faber C, Mueller S, Bartolomaeus T. Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging. BMC Biology. 2008;6(1):33.