Prognostic value of computed tomographic perfusion in the diagnosis of liver fibrosis and cirrhosis. Pilot study

Relevance: Most diffuse liver diseases lead to fibrosis over time with the risk of cirrhosis. With progressive fibrosis and cirrhosis of the liver both physical properties of the hepatic parenchyma and its hemodynamics change. The only reliable method for determining the stage of the disease is puncture biopsy and subsequent histological examination, but this method is invasive and associated with complications. Currently, the determination of the severity of cirrhosis is based on clinical data (the Child-Pugh scale) and elastography is considered to be the main non-invasive instrumental method. It lets reliably differentiate the initial fibrosis and cirrhosis of the liver, while the F2 and F3 stages according to the conventional METAVIR scale remain a "gray zone", as well as the differentiation of degrees of the severity of cirrhosis. In addition elastography has a  number of limitations. The main ones of which are operator dependence, apparatus dependence and the inability to determine functional changes in the liver. With the use of perfusion computed tomography (CT perfusion) it is possible to assess the functionality of the liver by quantifying changes in hemodynamics. The method applied measures the characteristics of blood flow in the tissue at a given scanning level by computed-tomographic data on the dynamics of the distribution of the contrast agent in the area of interest is collected, besides the type of liver perfusion is determined. This parameter is needed to assess the dynamics of treatment against the background of drug therapy.

Objective: To identify statistically significant parameters of CT perfusion to determine the severity of hemodynamic disturbances in patients with various stages of liver fibrosis and cirrhosis and to compare the values of parameters of liver CT perfusion with fibrosis according to the METAVIR conditional scale determined using elastography.

Materials and methods: 18  patients were included in this parallel pilot study. On the basis of clinical and laboratory data and the results of elastography, 10 of them were diagnosed with fibrosis and cirrhosis. The stages of fibrosis F1, F2 were determined in 3  patients; stages F3, F4  – in 7. In the group of patients with F3, F4, according to the METAVIR conditional scale, subgroups were distinguished depending on the severity of cirrhosis: compensated – 3 patients, subcompensated – 2, decompensated – 2. The control group consisted of 8 patients with organ diseases abdominal cavity not associated with liver damage. All patients underwent CT perfusion of the liver on a Philips iCT 256 using the following scan parameters: 80 KVp, 120 mAc, total scan time 56 s, and slice thickness 5.0 mm. Intravenously, bolus was administered to all patients with 50 ml of ioversol 350 mg/ml, the rate of administration was 3.8–4.0 ml/s, the time from the moment of administration of the contrast medium to the start of scanning was 6 s. After receiving a series of images, the data was processed on a Philips workstation. Quantitative analysis was carried out according to the following indicators: TTP (time to peak, s), BV (blood volume, ml/100 g), AP (arterial perfusion, ml/min/100 ml), PP (portal perfusion, ml/min/100  ml), TP (total perfusion, ml/min/100 ml) and HPI (hepatic perfusion index, %).

Results: In the control group of 8  patients, the perfusion values were: TTP 37.4±5.2  s, BV 16.1±5.0 ml/100 g, AP 25.0±7.5 ml/min/100 ml, PP 44.5±14.5 ml/min/100 ml, TP 70.1±14.9 ml/min/100 ml, HPI 70.1±14.9%. In 3 patients with F1, F2, according to the METAVIR conditional scale, the following statistically significant values (p<0.039) of perfusion indices were determined: BV 27.2±8.6  ml/100  g, AP 20.0±3.8  ml/min/100  ml; with compensated liver cirrhosis (n=3): TTP 46.2±1.7  s, BV 12.4±1.9  ml/100  g, AP 10.7±2.8 ml/min/100 ml, PP 37.3±5.2 ml/min/100 ml, TP 48.1±3.5  ml/min/100  ml, HPI 22.4±5.5%; subcompensated (n=2): TTP 43.0±3.2  s, BV 8.9±2.6 ml/100 g, AP 12.8±3.0 ml/min/100 ml, PP 27.7±9.0 ml/min/100 ml, TP 40.5±7.3 ml/min/100 ml; decompensated (n=2): BV 30.5±1.8 ml/100 g, PP 8.5±1.5 ml/min/100 ml, HPI 81.3±1.8%.

Conclusion: The preliminary results obtained confirm that CT perfusion can be used to predict and assess the severity of hemodynamic disturbances in patients with varying degrees of severity of cirrhosis and supplements clinical, laboratory and elastography data.