Liver enhancement in healthy dogs after gadoxetic acid administration during dynamic contrast-enhanced magnetic resonance imaging

Assessment of hepatitis and fibrosis using Gd-EOB-DTPA MRI in dogs

Background

Gadoxetate sodium (Gd-EOB-DTPA) is taken into hepatocytes and excreted into the bile. Hepatocytes with reduced function or dysfunction due to hepatocellular carcinoma (HCC), hepatitis or hepatic fibrosis show impaired Gd-EOB-DTPA uptake. The purpose of the present retrospective case series was to assess the relationship between liver function and contrast enhancement using Gd-EOB-DTPA MRI.

Methods

Sixteen dogs with a histopathological diagnosis of liver disease, including six with HCC, three with nodular hyperplasia, two with hepatocellular adenoma, two with liver fibrosis and three with hepatitis were included in the study along with three dogs with suspected liver disease but no histopathological diagnosis of liver disease. Relative signal intensities (RSI) of the common bile duct and gall bladder were calculated, and their relationship with the following serum biochemical parameters was assessed: total bilirubin, alanine transaminase, alkaline phosphatase and albumin (Alb). To assess anatomical liver function, relative contrast enhancement indices (RCEI) of the liver were calculated, and differences were assessed between normal and diseased liver.

Results

RSI showed no significant differences between dogs without and with a histopathological diagnosis of liver disease (P=0.88) although they were significantly correlated with Alb (ρ=0.57, P=0.02) in dogs with a histopathological diagnosis of liver disease. RCEI was significantly higher in normal liver tissue than that in livers with hepatitis/fibrosis (P=0.048) and HCC (P=0.03) but not nodular hyperplasia/hepatocellular adenoma (P=0.51).

Conclusions

Gd-EOB-DTPA MRI may be potentially useful in the assessment of anatomical liver function in dogs with liver disease.

Fuzzy Gray Level Difference Histogram Equalization for Medical Image Enhancement

Contrast enhancement methods are used to reduce image noise and increase the contrast of structures of interest. In medical images where the distinction between normal and abnormal tissue is subtle, accurate interpretation may become difficult if noise levels are relatively high. To provide accurate interpretation and clearer image for the observer with reduced noise levels "a novel adaptive fuzzy gray level difference histogram equalization algorithm" is proposed. At first, gray level difference of an input image is calculated using the binary similar patterns. Then, the gray level differences are fuzzified in order to deal the uncertainties present in the input image. Following the fuzzification, fuzzy gray level difference clip limit is computed to control the insignificant contrast enhancement. Finally, a fuzzy clipped histogram is equalized to obtain the contrast-enhanced MR medical image. The proposed algorithm is analysed both visually and analytically to calculate its performance against the other existing algorithms. Visual and analytical results on various test images affirm that the proposed algorithm outperforms all other existing algorithms and provide a clear path to analyse the fine details and infected portions effectively.

Influence of hepatic neoplasia on life expectancy in dogs

BACKGROUND AND AIM

The present study investigated the influence of liver tumor structure on life expectancy in dogs. Diseases of the liver comprise 5-25% of all non-communicable diseases in dogs, and primary hepatic tumors account for 0.6-1.3% of tumors. This research aimed to study the post-operative life span of animals with primary or metastatic tumors of the liver.

MATERIALS AND METHODS

During the study period, 7124 oncological operations were performed in our clinic. In total, 128 liver tumors were detected in live animals, while 323 were detected posthumously. Forty animals underwent surgery for various liver tumors. In dogs with primary liver tumors, the average age was 11.9 years and the average body weight was 15.5 kg, while in dogs with liver metastases, the mean age was 11.4 years and the average body weight was 24 kg.

RESULTS

The ratio of males to females among dogs with primary liver tumors was about 1:1 (ten females and nine males), while that among dogs with metastatic liver damage was clearly predominantly female (14 females and two males) because females often undergo surgery for cancerous mammary glands or ovaries.

CONCLUSION

The size of tumors and the number of affected lobes had a significant effect on the post-operative life span. With a tumor size of <5 cm and a lesion covering less than two lobes of the liver, life expectancy was significantly longer and the prognosis was more favorable. In cases of large tumors or those affecting more than two lobes, life expectancy was significantly reduced and the prognosis was cautious to unfavorable.

Magnetic resonance imaging of liver tumors using gadoxetic acid (Gd-EOB-DTPA) - pilot study

Background

Magnetic resonance imaging using gadoxetic acid, a hepatocyte-specific contrast agent, is one of the most useful MRI techniques used to diagnose liver tumours in humans. During the hepato-biliary phase, there is uptake of gadoxetic acid by normal hepatocytes, leading to hepatic parenchymal enhancement. This feature is used in human medicine to diagnose hepatic parenchymal metastatic disease, to differentiate primary liver tumours, to diagnose liver cirrhosis and focal nodular hyperplasia. This study presents the preliminary results of magnetic resonance imaging of focal lesions localised in the liver parenchyma in dogs following the administration of gadoxetic acid.

Results

The lesion enhancement ratio (ER_lesion) in the tumour metastasis was 0.05; the liver enhancement ratio (ER_liver) – 0.49 and the post-contrast lesion-to-liver contrast ratio (CR) was 0.17. In dogs with hepatocellular hyperplasia, these values were 0.54; 0.51; and 1.18, respectively. In two dogs with a hepatic adenoma, the ER_lesion was 0.26 and 0.17, respectively; the ER_liver was 0.47 and 0.47, respectively and the CR was 0.33 and 0.31, respectively. In the dog with a neuroendocrine tumour, the ER_lesion was 0.03; the ER_liver amounted to 0.58 and the CR was 0.35. In the case of a hepatocellular carcinoma, these coefficients were 0.2, 0.6 and 0.3, respectively.

Conclusion

Based on the results, it may be assumed that the MR images of the proliferative hepatic parenchymal lesions in dogs using gadoxetic acid are similar to those obtained in humans. This suggests that the contrast enhancement patterns used in human medicine may be useful in differentiating hepatic parenchymal lesions in dogs.