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

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Abstract

Background

Contrast-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.

Results

An 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.

Conclusion

CEUS 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.

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Most cited references 45

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An overview of clinical research: the lay of the land.

Thomas K F Schulz, D. Jay Grimes (2002)

Many clinicians report that they cannot read the medical literature critically. To address this difficulty, we provide a primer of clinical research for clinicians and researchers alike. Clinical research falls into two general categories: experimental and observational, based on whether the investigator assigns the exposures or not. Experimental trials can also be subdivided into two: randomised and non-randomised. Observational studies can be either analytical or descriptive. Analytical studies feature a comparison (control) group, whereas descriptive studies do not. Within analytical studies, cohort studies track people forward in time from exposure to outcome. By contrast, case-control studies work in reverse, tracing back from outcome to exposure. Cross-sectional studies are like a snapshot, which measures both exposure and outcome at one time point. Descriptive studies, such as case-series reports, do not have a comparison group. Thus, in this type of study, investigators cannot examine associations, a fact often forgotten or ignored. Measures of association, such as relative risk or odds ratio, are the preferred way of expressing results of dichotomous outcomes-eg, sick versus healthy. Confidence intervals around these measures indicate the precision of these results. Measures of association with confidence intervals reveal the strength, direction, and a plausible range of an effect as well as the likelihood of chance occurrence. By contrast, p values address only chance. Testing null hypotheses at a p value of 0.05 has no basis in medicine and should be discouraged.

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Quantification of renal blood flow with contrast-enhanced ultrasound.

Kevin Wei, Elizabeth Le, Jian-Ping Bin … (2001)

The goal of this study was to determine the ability of contrast-enhanced ultrasound (CEU) to quantify renal tissue perfusion. The kinetics of tracers used to assess renal perfusion are often complicated by countercurrent exchange, tubular transport or glomerular filtration. We hypothesized that, because gas-filled microbubbles are pure intravascular tracers with a rheology similar to that of red blood cells, CEU could be used to quantify renal tissue perfusion. During a continuous venous infusion of microbubbles (SonoVue), regional renal perfusion was quantified in nine dogs using CEU by destroying microbubbles and measuring their tissue replenishment with intermittent harmonic imaging. Both renal blood volume fraction and microbubble velocity were derived from pulsing-interval versus video-intensity plots. The product of the two was used to calculate renal nutrient blood flow. Renal arterial blood flow was independently measured with ultrasonic flow probes placed directly on the renal artery and was increased using dopamine and decreased by placement of a renal artery stenosis. An excellent correlation was found between cortical nutrient blood flow using microbubbles and ultrasonic flow probe-derived renal blood flow (r = 0.82, p < 0.001) over a wide range (2.5 fold) of flows. Ultrasound examination during microbubble infusion can be used to quantify total organ as well as regional nutrient blood flow to the kidney.

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Assessment of metastatic liver disease in patients with primary extrahepatic tumors by contrast-enhanced sonography versus CT and MRI.

Robert Fessl, Wolfgang Kratzer, Deike Strobe … (2006)

To evaluate contrast-enhanced ultrasonography (CEUS) using SonoVue in the detection of liver metastases in patients with known extrahepatic primary tumors versus the combined gold standard comprising CT, MRI and clinical/histological data. It is an international multicenter study, and there were 12 centres and 125 patients (64 males, 61 females, aged 59+/-11 years) involved, with 102 patients per protocol. Primary tumors were colorectal in 35%, breast in 27%, pancreatic in 17% and others in 21%. CEUS using SonoVue was employed with a low-mechanical-index technique and contrast-specific software using Siemens Elegra, Philips HDI 5000 and Acuson Sequoia; continuous scanning for at least five minutes. CEUS with SonoVue increased significantly the number of focal liver lesions detected versus unenhanced sonography. In 31.4% of the patients, more lesions were found after contrast enhancement. The total numbers of lesions detected were comparable with CEUS (55), triple-phase spiral CT (61) and MRI with a liver-specific contrast agent (53). Accuracy of detection of metastatic disease (i.e. at least one metastatic lesion) was significantly higher for CEUS (91.2%) than for unenhanced sonography (81.4%) and was similar to that of triple-phase spiral CT (89.2%). In 53 patients whose CEUS examination was negative, a follow-up examination 3-6 mo later confirmed the absence of metastatic lesions in 50 patients (94.4%). CEUS is proved to be reliable in the detection of liver metastases in patients with known extrahepatic primary tumors and suspected liver lesions.

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Author and article information

Contributors

Giordano Nardini

Nicola Di Girolamo

Stefania Leopardi

Irene Paganelli

Anna Zaghini

Francesco C Origgi

Massimo Vignoli

Journal

Journal ID (nlm-ta): BMC Vet Res

Journal ID (iso-abbrev): BMC Vet. Res

Title: BMC Veterinary Research

Publisher: BioMed Central

ISSN (Electronic): 1746-6148

Publication date Collection: 2014

Publication date (Electronic): 13 May 2014

Volume: 10

Page: 112

Affiliations

[1 ]Veterinary Clinic Modena Sud, Spilamberto, MO 41057, Italy

[2 ]Clinica per Animali Esotici, CVS, Rome 00137, Italy

[3 ]Department of Veterinary Medical Sciences, University of Bologna, Ozzano dell’Emilia, BO 40064, Italy

[4 ]Center for Fish and Wildlife Health (FIWI), College of Veterinary Medicine, University of Bern, Vetsuisse Faculty, Bern, CH 3012, Switzerland

[5 ]PetCare Veterinary Association, Marzabotto, BO 40043, Italy

Article

Publisher ID: 1746-6148-10-112

DOI: 10.1186/1746-6148-10-112

PMC ID: 4032566

PubMed ID: 24885935

SO-VID: 3a077f3f-94b8-43e2-bc06-4643f4224bbf

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

History

Date received : 15 January 2014

Date accepted : 1 May 2014

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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

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Most cited references 45

An overview of clinical research: the lay of the land.

Quantification of renal blood flow with contrast-enhanced ultrasound.

Assessment of metastatic liver disease in patients with primary extrahepatic tumors by contrast-enhanced sonography versus CT and MRI.

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