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G I RADIOLOGY Table of Contents   
Year : 2000  |  Volume : 10  |  Issue : 1  |  Page : 21-23
Reversal of portal flow in liver abscesses


1 Dept of Radiology, University College of Medical Science & GTB Hospital, New Delhi, India
2 Dept of Surgery, University College of Medical Science & GTB Hospital, New Delhi, India

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   Abstract 

Objective: To establish temporary change in portal hemodynamics (reversal of portal flow) in hepatic abscesses on color and duplex Doppler sonography Material and Methods: Twenty-five patients with clinically suspected and diagnosed liver abscesses on gray scale B mode real time imaging were evaluated by color and pulsed Doppler imaging. Results: Reversal of portal flow from one or more portal branches was seen in lesions measuring >10 cm in six out of ten cases of right lobe abscess and one out of four cases of left lobe abscess. Eight out of ten cases of multiple liver abscesses (both lobes) measuring >6cm, showed reversed flow. Normalization of flow occurred after treatment. Conclusion: Color and pulsed Doppler sonography allows noninvasive and rapid diagnosis of hepatofugal flow in early stages of hepatic abscesses. Thus early stage of hepatic abscess should be considered as one of the differential diagnosis of liver tumors with reversal of portal flow.

Keywords: Liver abscess, reversal of portal flow, color and duplex Doppler

How to cite this article:
Mehrotra P, Bhargava SK, Mehrotra P. Reversal of portal flow in liver abscesses. Indian J Radiol Imaging 2000;10:21-3

How to cite this URL:
Mehrotra P, Bhargava SK, Mehrotra P. Reversal of portal flow in liver abscesses. Indian J Radiol Imaging [serial online] 2000 [cited 2019 Jun 24];10:21-3. Available from: http://www.ijri.org/text.asp?2000/10/1/21/30626
Color flow Doppler imaging and Duplex scanning has many applications in the evaluation of the liver and the portal venous system. Doppler color imaging by passively superimposing Doppler information on the gray scale image as a color flow map, promptly identifies the major hepatic vessels, confirms their patency and evaluates flow direction and dynamics. Changes in intra hepatic portal hemodynamics particularly reversal of portal flow occur commonly in portal venous hypertension, advanced liver cirrhosis, portal venous thrombosis [1] and hepatic tumors particularly hepatocellular carcinoma. It is very rarely documented in patients with inflammatory diseases, especially hepatic abscesses (early stage) [2].

Liver abscess is the commonest intrahepatic lesion presenting as a hepatic mass and accounts for 48% of all visceral abscesses [3].

The aim of this study was to study the portal flow reversal in hepatic abscess on color and duplex Doppler sonography.


   Material and Methods Top


A total of twenty-five patients with clinically suspected and diagnosed liver abscesses on gray-scale imaging were included in the study. Patients already taking treatment or reporting for follow-up ultrasound after aspiration, patients with liver disease, suspected portal hypertension or diseases likely to cause change in portal hemodynamics were not included in this study. The mean age of the patients was 15-60 years.

All the patients were subjected to transabdominal real time B mode imaging followed by color and pulse Doppler imaging. All measurements were obtained using a 3.5 MHz sector transducer (Philips, P-700, Santa Ana). Wall-filter settings were kept at their lowest available value [50HZ] and pulse repetition frequency was adjusted manually to its lowest setting without aliasing. The axial size of the pulsed Doppler sample volume was kept in the 3-5 mm range. We always used a Doppler angle of incidence of less than 600.

All scans were conducted in the early morning after the patients had fasted overnight. The examination was performed in supine position. The patients were asked to stop breathing for recording a trace on a film. One tracing was obtained for each vessel. Flow measurements were obtained from the main portal vein intrahepatic) right and left portal veins and a branch of the portal vein at the periphery of the abscess using subcostal, longitudinal, right intercostal and epigastric approaches [Figure - 1]. Doppler waveforms were also recorded from the intrahepatic hepatic artery [Figure - 2] and IVC.

The criteria used for diagnosing any hepatic mass lesion as a hepatic abscess were; a hypoechoic space-occupying lesion in the liver, heterogeneous internal structure, hyperechoic margins and weak posterior acoustic enhancement supported by laboratory findings (marked increase in white blood cells and elevated alkaline phosphatase) and aspiration of pus (diagnostic tap).

Associated findings such as ascites, subdiaphragmatic collection of fluid, pericholecystic hypoechoic area, gall-bladder wall thickening, pleural effusion and other coexisting pathologies were also noted. A second US examination was done ten days later to show diminution of the abscess and normalization of flow direction.


   Results Top


Twenty five patients with early stage liver abscesses comprising of ten cases of multiple liver abscesses, ten cases of right lobe liver abscess and five cases of left lobe liver abscess were included in this study. Reversal of portal flow from one or more portal branches using color and duplex Doppler sonography was seen in six out of ten right lobe abscesses [Figure - 3] (measuring more than ten cm), eight out of ten cases of multiple liver abscesses (measuring more than six cm) and one out of five left lobe abscesses (measuring more than ten cm). However four out of ten cases measuring less than ten cm in the right lobe especially in the subdiaphragmatic region posteriorly, four out of five left lobe abscesses and two multiple liver abscesses less than six cm did not show reversal of portal flow [Table - 1].

All portal flow eventually returned to normal after treatment. Mean resistive index of the hepatic artery and peak flow velocity before treatment were: - Vmax 50.4 cm/sec, RI - 0.48 [Figure - 2], [Figure - 3] and after treatment - Vmax 25.4 cm/sec, RI -0.65 [Figure - 4],[Figure - 5].


   Discussion Top


Conventional Doppler sonography is now being used extensively to study hemodynamics within the liver. It passively and automatically depicts blood flow patterns and directions in real time [1]. This allows quick diagnosis of hepatofugal flow and the measurement of the resistive index (RI) helps in understanding the changes in hemodynamics over time. After analyzing Doppler signals there was no doubt that transient reversal of portal flow was seen at the periphery of the abscesses, during the active stage, but flow direction normalized after treatment. Analysis of the Doppler signal showed a decrease in the RI and an increase in the flow velocity in the hepatic artery followed by a decrease in the flow velocity and an increase in the RI, after normalization of flow in the branch of the portal vein running parallel to it. Similar observations were made by Chinami 1997 [4] who detected reversal of portal flow at the periphery of abscesses in two cases. However, our observations suggest that reversal of portal flow in acute (early stage) hepatic abscesses is much more common than reported [Figure - 1].

Linzy et al [2] observed that abscesses over 6cm showed reversal of portal flow and those measuring 6cm or less did not show this phenomenon. In our series, multiple liver abscesses, 6cm or less in size did not show reversal of portal flow. However in right and left lobe abscesses measuring more than 10cms, hepatofugal flow was seen whereas those measuring 10 cm or less did not show this. Thus a differential diagnosis of hepatic tumors with reversal of portal flow should also include early stage hepatic abscesses [5],[6].

Although the precise mechanisms still remain unclear, formation of transient arterio-portal shunts is the most accepted explanation.

Ralls 1990 [7] showed the communication site of an arteriovenous shunt by using color Doppler sonography. They postulated that visualization of a fistula with color Doppler sonography depends upon the size of the fistula. However we were unable to demonstrate arteriovenous shunt sites using Doppler sonography in our patients.

Arterialisation of pulsations of the portal vein on Doppler waveforms [8] also indirectly indicates an arterioportal shunt. However in our series, arterial waveforms in the portal vein were not detected on Doppler waveforms. However the simultaneous occurrence of an increase in arterial flow velocity and a decrease in the RI seen in our cases supports the hypothesis of transitory arterioportal shunt formation. The RI returned to normal simultaneously with normalization of portal flow.

To conclude, color and pulsed Doppler sonography helps in confirming the reversal of portal flow in the early stage of hepatic abscesses.

 
   References Top

1.Jeffrey RB JR, Ralls PW. The liver. In:Sonography of abdomen. New York: Raven Press 1995:71.  Back to cited text no. 1    
2.Linzy, Wang JH, Wang LY. Changes in intrahepatic portal hemodynamics in early stage hepatic abscesses. J Ultrasound Med 1996; 8: 595-598.  Back to cited text no. 2    
3.Zaleznik Dori F, Dennis L. Intraabdominal infections and abscesses. In: Harrisons. Principles of internal medicine, New York: Mc Graw- HillCompanies 14th edn. 1996: 794-795.  Back to cited text no. 3    
4.Chinami, Liver abscess with reversal of portal flow. Ultrasound International. 1997; 3: 135-138.  Back to cited text no. 4    
5.Tanaka S, Kitamura T, Fujita M.Color Doppler flow imaging of liver tumors. AJR 1990; 3: 509-574.   Back to cited text no. 5    
6.Miller MA, Balfe DM. Peripheral portal venous blood flow alterations by hepatic masses - evaluation with color and pulsed Doppler sonography. J US Med 1996; 10: 707-713.  Back to cited text no. 6    
7.Ralls PW. Color Doppler Sonography of the hepatic artery and portal venous system. AJR 1990; 3: 517-525.  Back to cited text no. 7    
8.Poniak MA, Baus KM. Hepatofugal arterial signal in main portal vein: an indicator of intravascular tumor spread. Radiology 1991; 180: 663-6.  Back to cited text no. 8    

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Correspondence Address:
Satish K Bhargava
Dept of Radiology and Imaging, University College of Medical Science & GTB Hospital, Dilshad Garden, New Delhi 110095
India
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Source of Support: None, Conflict of Interest: None


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    Figures

[Figure - 1], [Figure - 2], [Figure - 3], [Figure - 4], [Figure - 5]

    Tables

[Table - 1]



 

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