[Hepatic Doppler perfusion index--a sensitive screening method for detecting liver metastases?]

Potential use of Doppler perfusion index in detection of occult liver metastases from colorectal cancer

Many clinical and preclinical studies demonstrated that measurements of liver hemodynamic [Doppler perfusion index (DPI)] may be used to accurately diagnose and predict liver metastases from primary colorectal cancer in a research setting. However, Doppler measurements have some serious limitations when applied to general population. Ultrasound is very operator-dependent, and requires skilled examiners. Also, many conditions may limit the use of Doppler ultrasound and ultrasound in general, such as the presence of air in digestive tract, cardiac arrhythmias, vascular anomalies, obesity and other conditions. Therefore, in spite of the results from clinical studies, its value may be limited in everyday practice. On the contrary, scientific research of the DPI in detection of liver metastases is of great importance, since current research speaks strongly for the presence of systemic vasoactive substance responsible for observed hemodynamic changes. Identification of such a systemic vasoactive substance may lead to the development of a simple and reproducible laboratory test that may reliably identify the presence of occult liver metastases and therefore increase the success of adjuvant chemotherapy through better selection of patients. Further research in this subject is therefore of great importance.

The role of Doppler Perfusion Index as screening test in the characterization of focal liver lesions

PURPOSE

Doppler Perfusion Index (DPI) has been used in the detection of overt liver metastatic disease. In the present prospective study we evaluated the use of DPI in the differential diagnosis of liver tumours.

MATERIALS AND METHODS

We have included in our study 76 patients with focal hepatic lesion and 39 subjects as control group. All patients were evaluated by Color Doppler Ultrasound, and/or Spiral Computerised Tomography, Magnetic Resonance Imaging and biopsy. The radiologist performed DPI measurements was blind from the final diagnosis of the other methods.

RESULTS

DPI measurements in the control group ranged from 0.07 to 0.22 (mean value 0.14), in 42 cases with benign lesions (group A) ranged from 0.05 to 0.53 (mean 0.15) and in 34 cases with malignant lesions (group B) ranged from 0.39 to 0.75 (mean 0.53). There was a statistically significant difference in DPI measurements between the control group and group B.

CONCLUSIONS

Our results suggest that the DPI may differentiate malignant from benign focal hepatic lesions and therefore can be used as a screening test in the routine clinical practice.

Can biliary carcinoembryonic antigen identify colorectal cancer patients with occult hepatic metastases?

BACKGROUND

Twenty-five percent of radically treated colorectal cancer patients already have occult hepatic metastases (OHM) that will later be observed during postoperative follow-up. Instrumental examinations, i.e., intraoperative ultrasound or Doppler perfusion index, have not improved diagnosis. As carcinoembyonic antigen (CEA) levels are useful to reveal hepatic metastases from colorectal cancer, determination of CEA in the bile rather than the blood may allow preclinical diagnosis of OHM thanks to the reduced volume of bile.

METHODS

One hundred radically treated colorectal cancer patients were enrolled in the study. Bile was withdrawn from the gallbladder intraoperatively and biliary CEA levels determined using an immuno-enzymatic method (normal value 0-5 ng/ml). Eighty-nine fully evaluable patients were followed up for three years postoperatively to monitor hepatic metastases. Preoperative blood CEA, lymph node metastases and biliary CEA were compared in order to assess which procedure was more efficient in identifying patients who would develop hepatic metastases.

RESULTS

Eleven of the 89 evaluable patients developed hepatic metastases: 9/11 presented elevated biliary CEA levels (mean: 12.73; range: 5.1-26.2); 8/11 had high preoperative blood CEA values; and 9/11 were at anatomopathological stage N+. In the 78 patients who did not develop hepatic metastases, biliary CEA was within normal limits in 73/78, preoperative blood CEA was normal in 60/78, and 58/78 patients were at anatomopathological stage N-. Hence, the sensitivity of biliary CEA was 81.8%, specificity was 93.6%, and diagnostic accuracy was 92.1%.

CONCLUSIONS

Determination of biliary CEA seems to be more efficient in identifying patients presenting OHM who require frequent clinical examinations or adjuvant cancer treatment.

Contrast-enhanced Doppler perfusion index: clinical and experimental evaluation

OBJECTIVE

To assess the potential of the power Doppler signal intensity rate of enhancement due to contrast agent wash-in for assessment of hepatic hemodynamics.

METHODS

With the use of standardized settings, power Doppler sonography was performed before and after administration of a contrast agent. Video-recorded examinations were digitized for offline analysis on a personal computer. The temporal changes of the power Doppler signal intensity were quantified to provide contrast agent wash-in curves. The contrast-enhanced Doppler perfusion index was defined by the ratio of the wash-in gradient of the hepatic artery and portal vein as contrast-enhanced Doppler perfusion index = hepatic artery gradient/(hepatic artery gradient + portal vein gradient). The contrast-enhanced Doppler perfusion index was evaluated at 4 contrast agent doses in each of 14 patients with liver metastases and 3 patients with hemangiomas. An in vitro flow model was used to determine the relationships between the power Doppler rate of enhancement and flow in vessels of 4, 8, and 12 mm in diameter.

RESULTS

In vivo, there was a significantly higher (P < .0001) mean contrast enhanced Doppler perfusion index in patients with liver metastases (mean, 0.59; 95% confidence interval, 0.54-0.63), compared with patients with hemangiomas (mean, 0.33; 95% confidence interval, 0.24-0.41). The corresponding coefficients of variations were 25% for patients with liver metastases and 31% for patients with hemangiomas. In vitro, the power Doppler rate of enhancement was proportional to flow speed and independent of vessel diameter.

CONCLUSIONS

Measurement of the contrast-enhanced Doppler perfusion index may have potential in assessment of hepatic hemodynamics and focal liver disease.

Hepatic arterial blood flow in large hepatocellular carcinoma with or without portal vein thrombosis: assessment by transcutaneous duplex Doppler sonography

BACKGROUND

As liver cirrhosis progresses, the portal venous blood (PVBF) flow decreases, accompanied by an increase in hepatic arterial blood flow. Large hepatocellular carcinoma is a hypervascular tumour with a rapid growth, which seems to require an increase of the tumoral arterial blood flow. Furthermore, hepatocellular carcinoma is frequently associated with portal vein thrombosis, which subsequently impedes portal blood supply.

METHODS

The purpose of our study was to estimate alterations in the hepatic arterial blood flow in large hepatocellular carcinomas occurring in liver cirrhosis, in comparison with liver cirrhosis and controls. Liver blood flow measurements were determined by duplex Doppler sonography in 47 patients with large hepatocellular carcinomas (13 with portal vein thrombosis and 34 without this thrombosis), 42 liver cirrhosis patients and 30 controls. The Doppler perfusion index was calculated as the ratio of hepatic arterial blood flow to total hepatic blood flow.

RESULTS

The patients with liver cirrhosis had a significant increase of hepatic arterial blood flow as compared to controls (P < 0.001), accompanied by a significant reduction in PVBF (P < 0.005). As a result, the Doppler perfusion index was increased in patients with liver cirrhosis as compared to controls (P < 0.001). The hepatic arterial blood flow was increased in patients with hepatocellular carcinoma but without portal vein thrombosis as compared to the cirrhotic patients (P < 0.001), with a significant reduction of PVBF (P < 0.001). Hepatic arterial blood flow was also increased in patients with both hepatocellular carcinoma and portal vein thrombosis as compared to the patients without this thrombosis (P < 0.001).

CONCLUSION

These results suggest that in large hepatocellular carcinomas there is a decreased PVBF, accompanied by an increased hepatic arterial blood flow. The hepatic arterial buffer response seems to be active in hepatocellular carcinomas and maintains liver perfusion to adequate levels.