Evaluation of liver parenchyma and perfusion using dynamic contrast-enhanced computed tomography and contrast-enhanced ultrasonography in captive green iguanas (Iguana iguana) under general anesthesia

Abstract

BackgroundContrast-enhanced diagnostic imaging techniques are considered useful in veterinary and human medicine to evaluate liver perfusion and focal hepatic lesions. Although hepatic diseases are a common occurrence in reptile medicine, there is no reference to the use of contrast-enhanced ultrasound (CEUS) and contrast-enhanced computed tomography (CECT) to evaluate the liver in lizards. Therefore, the aim of this study was to evaluate the pattern of change in echogenicity and attenuation of the liver in green iguanas (Iguana iguana) after administration of specific contrast media.ResultsAn increase in liver echogenicity and density was evident during CEUS and CECT, respectively. In CEUS, the mean ± SD (median; range) peak enhancement was 19.9% ± 7.5 (18.3; 11.7-34.6). Time to peak enhancement was 134.0 ± 125.1 (68.4; 59.6-364.5) seconds. During CECT, first visualization of the contrast medium was at 3.6 ± 0.5 (4; 3-4) seconds in the aorta, 10.7 ± 2.2 (10.5; 7-14) seconds in the hepatic arteries, and 15 ± 4.5 (14.5; 10-24) seconds in the liver parenchyma. Time to peak was 14.1 ± 3.4 (13; 11-21) and 31 ± 9.6 (29; 23-45) seconds in the aorta and the liver parenchyma, respectively.ConclusionCEUS and dynamic CECT are practical means to determine liver hemodynamics in green iguanas. Distribution of contrast medium in iguana differed from mammals. Specific reference ranges of hepatic perfusion for diagnostic evaluation of the liver in iguanas are necessary since the use of mammalian references may lead the clinician to formulate incorrect diagnostic suspicions.

Contrast-enhanced computed tomography of the liver, gall bladder and urogenital tract in female red-eared terrapins (Trachemys scripta elegans)

“…For intravenous contrast medium administration, the jugular vein or the coccygeal vein were recommended as sites of administration in chelonians (Gumpenberger 2011). In our study, the jugular vein was used in contrast with the study from Nardini et al (2014). Differences in attenuation values may be expected when using different sites of administration due to the characteristic renal portal system in reptiles.…”

“…The first visualisation of the contrast medium in the aorta of eight green iguanas was recorded 3.6 ± 0.5 seconds after contrast medium administration (Nardini et al 2014). In red-eared terrapins, the peak aortic enhancement and the peak hepatic vein enhancement were recorded 20 seconds, and 20-60 seconds after contrast medium administration, respectively.…”

“…Variations in density may be caused by differences in blood pressure, heart rate or hydration between individual tortoises or may result from different methods for contrast medium administration and the different reptile species that have been used. The main limitation of this study was that we did not use an automated bolus tracking method as in the study of Nardini et al (2014). For intravenous contrast medium administration, the jugular vein or the coccygeal vein were recommended as sites of administration in chelonians (Gumpenberger 2011).…”

“…Contrast-enhanced computed tomography (CECT) represents an advanced, powerful diagnostic tool to evaluate organ morphology and perfusion in captive reptiles. However, only a few studies have so far evaluated the use of CECT in reptiles (Gumpenberger and Filip 2007;Gumpenberger 2011;Nardini et al 2014). The aim of the present study was to evaluate the feasibility of CECT in captive red-eared terrapins.…”

Sex Determination in Two Species of Anuran Amphibians by Magnetic Resonance Imaging and Ultrasound Techniques

“…In comparison with other imaging techniques, MRI constitutes a valuable tool that allows the easy visualization and differentiation of soft tissue structures. In addition, the possibility of an automatic self-adjustment of the equipment’s main technical parameters and the lower cost of the new low-field benchtop-MRI equipment has contributed to its more generalized use in preclinical research and in a daily veterinary clinic routine [ 31 , 32 , 33 , 34 , 35 ]. The present study is the first report of the use of BT-MRI for the purpose of sex determination.…”