Clinical diagnosis
Case 259
【Discussion】
Apparent diffusion coefficient (ADC) implies perfusion ability of water molecule. In an experimental study using animal model with squamous cell carcinoma, ADC value is the lowest in a stage of early mass forming tumor in liver, followed by in a moderate stage and finally in an advanced stage with necrosis: 0.7 in an early stage, 0.9 in a moderate stage and 1.0 in an advanced stage (1). This indicates that tumor needs some water diffusion inside the tumor for its growing or necrosis. Advanced tumor with necrosis elevates ADC values until around1.0 (2), while ADC value of malignant lymphoma that rare happens to cause necrosis is around 0.5 (3).
For interpretation of three malignant hepatic tumors of hepatocellular carcinoma (HCC), mass-forming intrahepatic cholangiocarcinoma (CCC) and metastatic liver cancer (Meta) from digestive organ, it is imperative to differentiate among them. Mean ADC values are 1.0 in HCC, 1.1 in CCC and 0.89 in Meta (1, 4). Of the three, ADC values are highest in CCC. As tumor grows, necrosis occurs in HCC and Meta, while fibrosis occurs in CCC. It is considered that necrotic area is a part of advanced cancer. The reason of slightly higher ADC values in advanced CCC rather than other two malignant hepatic tumor is probably because CCC include fibrotic area surrounded by viable tumor.
In our case, ADC value of the whole tumor, central area corresponded to fibrosis and marginal area corresponded to viable tumor is 1.2, 1.4 and 1.1, respectively. Our data supports that ADC values of CCC is affected by volume of fibrotic component, indicating slightly higher ADC values compared to metastatic tumors. It is sometimes difficult to differentiate between metastatic liver tumor and mass-forming intrahepatic CCC using contrast-enhanced dynamic CT or EOB MRI. The typical image of mass-forming intrahepatic CCC on Diffusion WIMRI is reported to be a target high signal intensity (4). ADC values can also contribute to differentiate between them.
Although ADC values of the three malignant hepatic tumors get lowering, it is rare that their ADC values are less than 0.7 (2, 4,5). ADC values of intrahepatic abscess vary from 0.3 to more than 1.0 depending on the stage of abscess which indicates water molecule is limited to active abscess, getting to acquire the potency of water molecule diffusion as time progress (5). Liver malignant lymphoma that cell density interrupts water molecule diffusion and affects lowering of ADC values: around 0.5 (3).
【Summary】
We presented a seventy four-year-old male for feeling unsteady on his feet. Laboratory test revealed high values of D-dimer that made him to recieive CT for suspicious pulmonary thrombus, vascular disease, liver disorder and cancerous lesion. Accidentally, CT showed liver SOL and Diffusion WIMRI depicted marginal high signal intensity called a target sign corresponded to the tumor. Mean ADC values of whole tumor, tumor center and tumor margin were 1.2, 1.4 and 1.1, respectively. It is borne in mind that ADC value of mass-forming intrahepatic CCC is relatively higher than other two malignancies of HCC and metastatic liver tumor probably because of the existence of fibrosis in its center. The mean ADC value of metastatic liver tumor, HCC and mass-forming intrahepatic CCC is 0.9, 1.0 and 1.1, respectively.
【References】
1.Herneth AM, et al. Apparent diffusion coefficient: a quantitative parameter for in vivo tumor characterization. Eur J Radiol. 2003;45(3):208-13
2.Kong E, et al. Quantitative assessment of simultaneous F-18 FDG PET/MRI in patients with various types of hepatic tumors: Correlation between glucose metabolism and apparent diffusion coefficient. PLoS One. 2017; 12(7): e0180-184
3.Maeda M, et al. Apparent diffusion coefficient in malignant lymphoma and carcinoma involving cavernous sinus evaluated by line scan diffusion-weighted imaging. J Magn Reson Imaging 2006;24:543-548
4.Lee J, et al. Mass-forming Intrahepatic Cholangiocarcinoma: Diffusion-weighted Imaging as a Preoperative Prognostic Marker. Radiology 2016; 281: 119-128
5.Kilickesmez O, et al. Diffusion-Weighted Imaging Features of Urachal Abscess. Istanbul Training and Research Hospital. 2008 DOI:10.15659/yeditepemj.15.10.250
2022.3.1