Abstract
Hepatocellular carcinoma (HCC) and liver metastases are an increasing problem worldwide. Non-invasive methods for understanding of HCC growth mechanisms are highly desirable. A biexponential model for analysis of non-invasive diffusion-weighted 1 H magnetic resonance imaging (MRI) provides important information about neoplastic transformation in capillary liver tissue perfusion and water molecular diffusion. Fast and slow components of water apparent diffusion coefficient (ADC) were separated in the normal rat liver, intrahepatic, and subcutaneous HCCs. MRI was acquired with a Varian 9.4 T horizontal bore system. The fast component of ADC (ADC fast ), which contributes 38% to total signal in the intrahepatic HCC, was significantly lower compared to normal liver value, while the slow component of ADC did not differ in liver, intrahepatic, and subcutaneous HCCs. A decrease in ADC fast may be caused by restricted perfusion in abnormal tumor microvessels. Thus, a reported earlier decrease in ADC in HCC compared to normal liver was mostly due to a decreased in tumor perfusion rather than a decrease in water diffusion. Subcutaneous HCC showed a very limited vasculature development, which makes the tumor perfusion extremely poor and hypoxic. Simultaneous monitoring of water ADC changes in orthotopic and subcutaneous HCCs may be useful, but a possibility of location-based physiological and metabolic differences must be recognized. Keywords: hepatocellular carcinoma, 1 H-MRI, apparent diffusion coefficient, perfusion, tumor location.
Highlights
Hepatocellular carcinoma (HCC) and liver metastases from other tumors are an increasing problem worldwide due to the major risk factors of HCC growth, such as cirrhosis and hepatitis, which cause genetic changes that lead to neoplastic transformations [19]
Both intrahepatic and subcutaneous HCCs are marked by T-arrows and liver is marked by L-arrow while reference containing 0.03% NaCl is marked by R- arrow
The images of the liver containing HCC was slightly blurred with b-values of 100-1600 s/mm2 even though they were collected with respiratory gating, the apparent diffusion coefficient of water (ADC) map showed only a fair motion effect in the liver region [1, 2]
Summary
Hepatocellular carcinoma (HCC) and liver metastases from other tumors are an increasing problem worldwide due to the major risk factors of HCC growth, such as cirrhosis and hepatitis, which cause genetic changes that lead to neoplastic transformations [19]. Bansal from diffusion-weighted 1H MRI (DWI), water ADC may reflect diffusion that represents mostly the Brownian motion of the water molecules, and perfusion in microvessels, in tissues with a rich vasculature such as normal liver and intrahepatic HCC [10]. In addition to molecular diffusion and tissue perfusion, in vivo ADC measurements can be sensitive to respiratory and cardiac motion [18]. In order to avoid possible motion artifacts and/or to obtain high quality MRI, subcutaneous tumor models instead of orthotopic models are frequently used [4, 11, 14, 15, 20, 24, 27]. The tumor microenvironment can be significantly affecting by nearby host tissue influencing water ADC in the tumor. Simultaneous assessment of perfusion and diffusion in intrahepatic and subcutaneous HCCs has not been performed
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