An experimental approach of the Doppler perfusion index of the liver in detecting occult hepatic metastases: histological findings related to the hemodynamic measurements in Wistar rats

Chick Embryo Experimental Platform for Micrometastases Research in a 3D Tissue Engineering Model: Cancer Biology, Drug Development, and Nanotechnology Applications

Colonization of distant organs by tumor cells is a critical step of cancer progression. The initial avascular stage of this process (micrometastasis) remains almost inaccessible to study due to the lack of relevant experimental approaches. Herein, we introduce an in vitro/in vivo model of organ-specific micrometastases of triple-negative breast cancer (TNBC) that is fully implemented in a cost-efficient chick embryo (CE) experimental platform. The model was built as three-dimensional (3D) tissue engineering constructs (TECs) combining human MDA-MB-231 cells and decellularized CE organ-specific scaffolds. TNBC cells colonized CE organ-specific scaffolds in 2–3 weeks, forming tissue-like structures. The feasibility of this methodology for basic cancer research, drug development, and nanomedicine was demonstrated on a model of hepatic micrometastasis of TNBC. We revealed that MDA-MB-231 differentially colonize parenchymal and stromal compartments of the liver-specific extracellular matrix (LS-ECM) and become more resistant to the treatment with molecular doxorubicin (Dox) and Dox-loaded mesoporous silica nanoparticles than in monolayer cultures. When grafted on CE chorioallantoic membrane, LS-ECM-based TECs induced angiogenic switch. These findings may have important implications for the diagnosis and treatment of TNBC. The methodology established here is scalable and adaptable for pharmacological testing and cancer biology research of various metastatic and primary tumors.

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.

Relationship between CT volumetric measurements and Doppler perfusion indices in gastrointestinal liver metastasis

PURPOSE

This study investigated how the volume of hepatic metastatic lesions can affect liver haemodynamics and whether these perfusion parameters may help to differentiate benign and malignant liver lesions.

MATERIALS AND METHODS

The Doppler perfusion index (DPI the ratio of arterial to total liver blood flow) was measured in 46 patients aged 29-83 years, exhibiting up to four focal hyperechoic liver lesions at ultrasound examination. They comprised histopathologically proven liver metastasis of colorectal (19 cases) and gastric (10 cases) adenocarcinoma without local recurrence at the site of the previously resected primary tumour, along with 17 subjects with haemangioma. All patients underwent volumetric assessment using multislice computed tomography to calculate total volume of hepatic lesions.

RESULTS

The mean DPI of patients with colorectal (36 ± 2 %) and gastric (39 ± 6 %) metastasis was significantly higher than those with haemangioma (14 ± 2 %) (both p < 0.001), whereas metastatic groups did not exhibit any difference in terms of mean DPI. Statistically significant correlations were found between DPI values and calculated total volume of lesions in patients with colorectal and gastric metastasis (r = 0.55, p = 0.01 and r = 0.85, p = 0.002, respectively) while this correlation was not demonstrated in the haemangioma group. Simple linear regression analysis revealed that every 1 cm(3) increment in total volume of metastatic lesions increased DPI by 0.2 % [95 % confidence interval (CI) 0.1-0.3, p = 0.001].

CONCLUSION

Doppler perfusion index alterations are directly correlated with total volume of metastatic deposits, and DPI measurement can be a valuable method to distinguish haemangioma from hyperechoic colorectal and gastric metastatic lesions.

Tumour progression and liver regeneration--insights from animal models

Surgery remains the only curative treatment for colorectal liver metastases. For patients with multiple bilobar spread, extended hepatectomy might be required to achieve complete margin-free resection. In such cases, portal vein occlusion has been developed to induce preoperative hypertrophy of the future remnant liver and increase the resectability rate. Evidence now suggests that liver regeneration after hepatectomy and portal vein occlusion has a protumorigenic role, either through an upregulation of growth factors and cytokines or by haemodynamic changes in the blood supply to the liver. Experimental studies have reported a stimulatory effect of liver regeneration on the tumoral volume of liver metastases and on the metastatic potential of cells engrafted in the liver; this effect seems to depend on the timing of hepatectomy and portal vein occlusion. However, the variability of animal tumour models that are used for research in experimental colorectal liver metastases might account for some of the inconsistent and conflicting results. This Review presents clinical and experimental data pertaining to whether liver regeneration causes proliferation of tumour cells. We also analyse the different animal models of colorectal liver metastases in use and discuss current controversies in the field.

Hepatic transit time analysis using contrast enhanced MRI with Gd-BOPTA: A prospective study comparing patients with liver metastases from colorectal cancer and healthy volunteers

PURPOSE

To find out if the hepatic transit time (HTT) shortening, which was already proven in patients with liver metastases by other modalities, can also be detected with MRI.

MATERIALS AND METHODS

The Patient group consisted of 20 subjects with liver metastases from colorectal cancer and the control group of 21 healthy subjects. Baseline and post contrast images were acquired before and after administration of Gd-BOPTA, using a T1-weighted bolus test sequence. Arrival times (AT) of the contrast agent for the aorta, the hepatic artery, the portal vein and one hepatic vein were determined. Based on arrival time measurements HTT were calculated.

RESULTS

All analyses showed significantly shorter HTT in patients with metastases compared with healthy volunteers (P < 0.05). There were no false positives using a threshold of 10.4 s for arterial to venous HTT. For aortal to venous and portal to venous HTT a threshold of 12.5 s and 4 s was calculated, respectively. No significant correlation between HTT and involved liver segments, overall volume of metastases or subject age was found.

CONCLUSION

We conclude that HTT measurements using contrast enhanced MRI with Gd-BOPTA can detect hemodynamic changes due to metastatic liver disease from colorectal cancer.

Tumor and non-tumor liver angiogenesis is traced and evaluated by hepatic arterial ultrasound in murine models

We studied the relationships between hepatic and mesenteric mean blood-flow velocities (mBFVs) measured by ultrasound imaging and (1) downstream tumor angiogenesis during liver metastasis induced by spleen injection of LS174 human colon cells overexpressing the antiangiogenic Netrin4 (LS174-NT4) or not (LS174-WT) and (2) downstream normal angiogenesis during hepatic regeneration after 50% hepatectomy. Liver volume and mBFVs were measured before and after surgery, at day 30 in the first model and at days 2, 7 and 16 in the second model. LS174-NT-4 vs. LS174-WT mice presented fewer metastases (25% vs. 90%, p < 0.001) and decreased hepatic mBFVs (16.5 ± 0.8 vs. 21.8 ± 1.4 cm s(-1), p < 0.01), without difference in mesenteric mBFVs. After partial hepatectomy, hepatic and mesenteric mBFVs increased at day 7, from 12.4 ± 1.7 and 11.8 ± 2.6 to 19.1 ± 1.8 and 17.5 ± 2.4 cm s(-1), respectively, (p < 0.01) then returned to baseline as liver volume. Duplex Doppler ultrasonography reliably assesses normal or tumor angiogenesis and may provide follow-up functional evaluation.

Hepatic transit time analysis using contrast-enhanced ultrasound with BR1: A prospective study comparing patients with liver metastases from colorectal cancer with healthy volunteers

We prospectively compared hepatic transit time (HTT) measurements in subjects with liver metastases from colorectal cancer (group a) and healthy volunteers (group b) using contrast-enhanced ultrasound with BR1. The purpose of this study was to verify our hypothesis that the hemodynamic changes of the liver, which occur during metastasis seeding, would shorten the HTT, and we expect that such changes could be used for the detection of occult liver metastases from colorectal cancer in the future. The study had institutional review board approval and all subjects gave informed written consent. Group a and group b consisted of 22 subjects each. Baseline and post contrast images were acquired starting 10 s before and ending 40 s after administration of BR1, using nonlinear imaging at a frame rate of 5/s. The baseline images were used to determine the signal intensity without contrast enhancement as the reference signal. Arrival times (AT) of the contrast agent for the hepatic artery, the portal vein and one hepatic vein were determined using (i) quantitative analysis and (ii) subjective analysis by two blinded readers. HTT was calculated based on arrival time measurements. Quantitative and subjective analysis showed significantly shorter arterial to venous and portal to venous HTT in group a compared with group b (p < 0.001). Arterial to venous HTT (quantitative analysis) was < or = 9 s in 19 of 22 subjects of group a and >9 s in 18 of 22 subjects of group b (sensitivity 86%, specificity 82%, positive predictive value 83%, negative predictive value 86%, area under the curve [AUC] 0.87). Portal to venous HTT (quantitative analysis) was < 7 s in 21 of 22 subjects of group a and > 7s in 15 of 22 subjects of group b (sensitivity 95%, specificity 68%, PPV 75%, NPV 94%, AUC 0.85). There was an inverse relation with number of liver segments involved for arterial to venous and portal to venous HTT in group a (p < 0.05), but no correlation between HTT and overall volume of metastases (group a) or subject age (group b). From the results of our study, we conclude that HTT measurements using contrast-enhanced ultrasound with BR1 can detect hemodynamic changes caused by metastatic liver disease from colorectal cancer. However, comparison with the literature suggests that the use of other contrast agents might provide better results. Comparison of different contrast agents for the purpose of transit time analysis would therefore be useful before embarking on a prospective trial looking at the detection of occult liver metastases in patients with colorectal cancer. (E-mail: jhohmann@uhbs.ch).

Doppler ultrasonography of hepatic artery in malignant liver tumors

Hepatic artery is dominant compared to portal vein in liver tumor vascularization. Malignant tumors have uncontrolled growth and spread onto neighbouring tissues through a tumor vascular network. Based on this we discussed the use arterial flow parameters including systolic and diastolic speed, Doppler perfusion index, and resistance index for early detection of liver metastasis. We also discussed possibility to make differential diagnosis from other disease such as arterial stenosis, liver cirrhosis, steatosis using these parameters in better diagnosis confirmation.

[Doppler hemodynamic study in evaluation of liver metastases]

The color Doppler spectral analyses can be usefully in description of the liver circulation as one from non-invasive methods. Using color Doppler B mod ultrasound (Toshiba Core Vision) with duplex ultrasound we founded difference in liver circulation between patients with colon cancer and liver metastasis in comparison with those without metastases. We suggested this non invasive method for early detection of occult liver metastasis presence.

Changes of Intratumoral Microvessels and Blood Perfusion during Establishment of Hepatic Metastases in Mice

PURPOSE

To prospectively evaluate the stepwise changes that occur in intratumoral microvessels and microcirculation during the establishment of murine colonic hepatic metastases by using in vivo fluorescent microscopy and to compare the changes with tumor angiogenesis evaluated with an immunohistochemical study.

MATERIALS AND METHODS

This study was approved by the institutional animal care and use committee. Twenty-five mice with hepatic metastases created with injection of murine colonic adenocarcinoma (colon 26) tumor cells into the spleen were examined with in vivo microscopy and immunohistochemical study for CD34, intracellular adhesion molecule (ICAM-1), and alpha smooth muscle actin (alpha-SMA). The tumor size, microcirculation in tumors, intratumoral microvessel density (MVD), afferent MVD, and CD34-positive MVD were evaluated. The data among the tumors that showed different hemodynamic or immunohistochemical patterns were compared with the Kruskal-Wallis test and the Student t test.

RESULTS

Four stepwise patterns were observed according to the changes in morphology, hemodynamics, and immunohistochemical characteristics of intratumoral microvessels during the establishment of hepatic metastases, as follows: metastases without definite intratumoral blood perfusion or any intratumoral microvessels (mean diameter, approximately 180 microm), metastases with portal perfusion and intratumoral ICAM-1-positive residual hepatic sinusoids (mean diameter, approximately 290 microm), metastases with mixed portal and arterial perfusion and increased CD34-positive microvessels and alpha-SMA-positive arterioles (mean diameter, approximately 520 microm), and metastases with exclusively arterial perfusion and increased CD34-positive microvessels and alpha-SMA-positive arterioles (mean diameter, >2000 microm). The differences among the mean sizes of the tumors that showed these four patterns were statistically significant (P < .01).

CONCLUSION

Stepwise changes of intratumoral microcirculation were revealed from direct diffusion, to portal perfusion, to mixed portal and arterial perfusion, and finally to arterial perfusion in accordance with stepwise tumor neovascularization during the growth of murine colonic hepatic metastases.

Preoperative imaging staging of rectal cancer

Carcinomas of the rectum are associated with a significant local and distant recurrence rate. Not all patients are appropriate candidates for preoperative radiation therapy. Preoperative identification of those most likely to benefit from neoadjuvant therapy is important. There is no general consensus on the role of endorectal ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI) in staging patients with rectal cancer. Although the tumor stage is an important prognostic factor, preoperative assessment is associated with prediction of the circumferential resection margin. Newer developments such as coils, sequences and gradients in MRI, evolution of multidetector CT and new contrast media, allow for an algorithm selection aiming at the best diagnostic options for patients. The present review will discuss the current role of the various imaging modalities in staging carcinomas of the rectum.

Doppler sonographic evaluation of hemodynamic changes in colorectal liver metastases relative to liver size

OBJECTIVE

The mechanisms of hemodynamic alterations in colorectal liver metastases are not clearly understood yet. Considering that an increase in liver size in patients with metastases could also result in an alteration in total liver flow, we aimed to analyze hemodynamic changes relative to the liver volume and to search for the possibility of any intrinsic factors affecting blood flow in patients with metastases.

METHODS

Twenty-eight patients with colorectal liver metastases and 20 control subjects with no liver disease were evaluated sonographically. All patients were examined prospectively by Doppler sonography and helical computed tomography. Hepatic hemodynamic parameters, including blood flow in the hepatic artery and portal vein, total blood flow to the liver, and Doppler perfusion index, were calculated, and values relative to liver volume were obtained. Hepatic perfusion changes in liver metastases were then compared with those in a control group.

RESULTS

The liver volume of the patients with liver metastases was greater than that of the control group (P=.003). Hepatic arterial blood flow rates were higher, whereas portal flow rates were lower, in patients with liver metastases compared with control subjects (P<.05). Total liver blood flow was not significantly different between the two groups. However, total blood flow relative to liver volume was significantly lower in the metastatic group (P<.001). Doppler perfusion index values in the patients with metastasis were significantly higher than in the control group (P=.000).

CONCLUSIONS

Our findings may support the hypothesis that a humoral mediator-induced portal venous flow reduction causes perfusion changes in liver metastases from colorectal disease. However, an additional intrinsic hepatic hemodynamic event should also be present. Doppler perfusion index measurements can provide additional information in the evaluation of patients with colorectal liver metastases.

Doppler perfusion index fails to predict the presence of occult hepatic colorectal metastases

AIMS

To assess the predictive value of the Doppler perfusion index (DPI) in a cohort of patients with colorectal cancer with and without initial metastatic disease and present the data of at least 4 years follow-up.

METHODS

We studied 133 patients admitted with stage I-IV colorectal cancer. In all patients hepatic flow measurements were performed in the week before surgery. All patients who underwent curative surgery on intention were followed up for at least 4 years.

RESULTS

Reliable DPI measurements were not possible in 29 patients. Three groups were defined for comparison: (A) 57 patients who remained disease free, (B) 11 patients who presented with metachronous liver metastases during follow-up and (C) 19 patients with liver metastases at initial presentation. No significant difference was found for DPI data between the three groups. There was a trend for a higher hepatic artery flow in patients with initial liver metastases compared to those who remained disease free (p=0.07). The previously reported cut-off point for maximal normal DPI (0.3) did not have any predictive value in this patient cohort.

CONCLUSION

The present data do not confirm the usefulness of DPI measurements in daily clinical practice for the early identification of patients with colorectal cancer at high risk for recurrent disease.

Nature of Doppler perfusion index changes in patients with colorectal cancer liver metastases

OBJECTIVE

Occult hepatic metastases from colorectal cancer result in an increase of the ratio of arterial hepatic blood flow to total hepatic blood flow, described as the Doppler perfusion index. Whether this alteration is due to an increase in arterial blood flow or a decrease in portal venous inflow has not yet been unequivocally determined. The purpose of this study was to analyze changes in hepatic perfusion in patients with liver metastases from colorectal cancer by standardization of hemodynamic parameters to body surface area.

METHODS

Hemodynamic parameters (crosssectional area, blood flow, and congestive index) were measured for the common hepatic artery and portal vein with duplex color Doppler sonography in 20 patients with liver metastases and 20 healthy control subjects and evaluated relative to body surface area.

RESULTS

No statistically significant differences in age, body surface area, cross-sectional area of the common hepatic artery, and congestion index of the common hepatic artery and portal vein were observed between control subjects and patients with liver metastases. Patients with liver metastases had significantly greater arterial hepatic blood flow and Doppler perfusion index and significantly smaller portal cross-sectional area portal blood flow as well as total liver blood flow (P <.001).

CONCLUSIONS

This study supports the theory that the primary mechanism of alteration in liver perfusion is the reduction of portal inflow with subsequently increased arterial hepatic blood flow.

Hepatic perfusion changes in mice livers with developing colorectal cancer metastases

PURPOSE

To evaluate whether intrahepatic flow alterations occur during formation of hepatic colorectal cancer metastases and to identify possible causes of these alterations.

MATERIALS AND METHODS

Intravital imaging of exteriorized livers was performed in 72 live mice. Three groups of mice were studied: a sham-operated control group (n = 24), a group with nonmetastasizing subcutaneous gliomas (n = 24), and a group with developing hepatic CX-1 colon cancer metastases (n = 24). Microvascular flow parameters, leukocyte-endothelial interactions, and wall shear stress were directly measured in hepatic sinusoids and postsinusoidal venules at 2-day intervals prior to and during the development of metastases. The Kruskal-Wallis test was used initially to test for overall equality of medians in each data group. Single posttest comparisons of independent samples were performed with the Mann-Whitney test, with an overall statistical significance of .05.

RESULTS

Prior to the development of visible colorectal cancer metastases, significant (P <.05) reductions occurred in sinusoidal and postsinusoidal flow and wall shear rates, coupled with increased leukocyte rolling and adherence. With tumor growth, flow was further compromised in 92% of tumors larger than 0.5 mm in diameter by extrinsic compression of sinusoids and portal venules and narrowing caused by adherent leukocytes.

CONCLUSION

Significant intrahepatic flow alterations occur in mouse livers prior to growth of visible metastases and provide a rational explanation for elevation in the Doppler perfusion index that occurs prior to tumor formation.

Liver metastases in cancer: detection with contrast-enhanced ultrasonography

In patients with known or suspected malignancy, ultrasonography (US) is often the first choice for liver imaging because of its widespread availability and low cost. Compared with contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI), the sensitivity of conventional US for detecting hepatic metastases is relatively poor. The advent of microbubble contrast agents changed this situation. Sensitivity and specificity increased substantially with the use of these contrast agents and contrast-specific imaging modes in recent years. Currently, numerous US imaging methods exist, based on Doppler techniques or harmonic imaging. They exploit the complex nonlinear behavior of microbubbles in a sound field to achieve marked augmentation of the US signal. Although microbubble contrast agents are essentially blood pool agents, some have a hepatosplenic specific late phase. Imaging during this late phase is particularly useful for improving the detection of malignant liver lesions and allows US to perform similarly to spiral CT as shown by recent studies. In addition, this late phase imaging is very helpful for lesion characterization. Low mechanical index imaging with the newer perfluor agents permits real-time imaging of the dynamic contrast behavior during the arterial, portal venous, and late phases and is particularly helpful for lesion characterization. The use of US for hemodynamic studies of the liver transit time may detect blood flow changes induced by micrometastases even before they become visible on imaging. In this field of functional imaging, further research is required to achieve conclusive results, which are not yet available.

Ultrasonographic detection of focal liver lesions: increased sensitivity and specificity with microbubble contrast agents

Ultrasonography (US) is the first choice for screening patients with suspected liver lesions. However, due to a lack of contrast agents, US used to be less sensitive and specific compared with computed tomography (CT) and magnet resonance imaging (MRI). The advent of microbubble contrast agents increased both sensitivity and specificity dramatically. Rapid developments of the contrast agents as well as of special imaging techniques were made in recent years. Today numerous different US imaging methods exist which based either on Doppler or on harmonic imaging. They are using the particular behaviour of microbubbles in a sound field which varies depending on the energy of insonation (low/high mechanical index, MI) as well as on the properties of the agent themselves. Apart from just blood pool enhancement some agents have a hepatosplenic specific late phase. US imaging during this late phase using relatively high MI in phase inversion mode (harmonic imaging) or stimulated acoustic emission (SAE; Doppler method) markedly improves the detection of focal liver lesions and is also very helpful for lesion characterisation. With regards to detection, contrast enhanced US performs similarly to CT as shown by recent studies. Early results of studies using low MI imaging and the newer perfluor agents are also showing promising results for lesion detection. Low MI imaging with these agents has the advantage of real time imaging and is particularly helpful for characterisation of focal lesions based on their dynamic contrast behaviour. Apart from the techniques which based on the morphology of liver lesions there were some attempts for the detection of occult metastases or micrometastases by means of liver blood flow changes. Also in this field the use of US contrast agents appears to have advantages over formerly used non contrast-enhanced methods although no conclusive results are available yet.

Application of poly-lactide-co-glycolide-microspheres in the transarterial chemoembolization in an animal model of hepatocellular carcinoma

AIM: To introduce an animal model of hepatocellular carcinoma (HCC) in ACI-rats, and to evaluate the therapeutic effects of Poly-lactide-co-glycolide(Plcg)-microspheres in the transarterial chemoembolization (TACE) in this model, as well the value of this model in the experiments of interventional therapy.

METHODS: Subcapsular implantation of a solid Morris Hepatoma 3924A (1 mm³) in the livers was carried out in 11 male ACI-rats. The tumor volume (V1) was measured by magnetic resonance imaging (MRI) (13 days after implantation). After laparotomy and retrograde placement of catheter into the gastroduodenal artery (14 days after implantation), the following protocols of interventional treatment were performed: (A) mitomycin C+Poly-lactide-co-glycolide(Plcg)-microspheres (n = 4); (B) 0.9% NaCl (control group, n = 7). 13 days after these therapies the change of the tumor volume (V2) was determined by MRI again.

RESULTS: The success rate of tumor implantation reached to 100%. The mean tumor volume before TACE (V1) were 0.082 cm³ in group A and 0.096 cm³ in group B respectively. The mean tumor volume after TACE (V2) were 0.230 cm³ in group A and 1.347 cm³ in group B respectively. The mean V2/V1 were 2.860 in group A and 27.120 in group B respectively. Compared to the control group (group B), groups A showed a significant reduction of tumor growth (P = 0.004) in the period of observation.

CONCLUSION: The growth of liver tumor could be obviously prevented by utilizing Plcg-mitomycin-microspheres in TACE in animal model. This rat model of HCC is suitable for the experimental studies of interventional therapy.

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.