Amoebic Liver Necrosis in Contrast-Enhanced Ultrasound [November 2023]

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Amoebic Liver Necrosis in Contrast-Enhanced Ultrasound

Authors: Ehsan Safai Zadeh, M.D., and Helmut Prosch, M.D.
– Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna General Hospital, Vienna, Austria.

Figure 1: A 44-year-old male patient presented with infectious liver lesions due to amoebic infection in CT (A) and B-mode ultrasound (B). On contrast-enhanced ultrasound, the lesions consistently showed a predominant absence of enhancement throughout the examination, with no rim enhancement in the arterial phase (C) or perilesional wash-out in the portal venous phase (D). The septa exhibited contrast enhancement.

Figure 2: A 31-year-old male patient with cytologically confirmed streptococcal infection seen in CT (A) and B-mode ultrasound (B). On contrast-enhanced ultrasound (CEUS), the lesions consistently showed a central absent enhancement, with rim enhancement in the arterial phase (C) und perilesional wash-out in the portal venous phase (D).

1Clinical History

A 44-year-old patient with fever, weakness, bloody stools, and elevated infectious markers presented at the emergency department. The patient had multiple recent visits to India. In the stool analysis using multiplex PCR, Entamoeba histolytica was detected. Computed tomography identified several partially septated lesions suggestive of amoebic liver necrosis.

2Image findings

B-mode ultrasound (B-US) revealed several anechoic, partially septated lesions in the liver. On contrast-enhanced ultrasound (CEUS), the lesions consistently displayed a predominant absence of enhancement throughout the examination, with no rim enhancement in the arterial phase or perilesional wash-out in the portal venous phase. The septa showed contrast enhancement (Fig 1).

3Diagnosis

Amoebic necrosis of the liver.

4Discussion

Infectious liver lesions display different CEUS patterns dependent on the pathogen involved. Unlike pyogenic abscesses (Fig 2), amoebic liver lesions—often termed sterile abscesses—lack a defined wall, show no rim enhancement in the arterial phase, and exhibit no peripheral wash-out in the portal venous phase.

5Teaching Points

-An infectious amoebic lesion of the liver, if not secondarily infected, constitutes sterile necrosis. Enhancement of the septa may be observed.

-Unlike pyogenic abscesses (Fig 2), these lesions do not show pronounced rim enhancement or wash-out phenomena on CEUS, which would indicate inflammatory obstruction of the portal vein branches in pyogenic abscesses.

- The term "liver abscess" refers to a collection of pus (neutrophil granulocytes) in the liver and should not be applied to infectious amoebic lesions. Instead, "amoebic necrosis" is the preferred nomenclature. A therapeutic evacuation of the lesion is not necessary.

6References

1. Kunze G, Staritz M, Köhler M. Contrast-enhanced ultrasound in different stages of pyogenic liver abscess. Ultrasound Med Biol. 2015; 41(4): 952-959.

2. Sayek I, Onat D. Pyogenic and amebic liver abscess. In: Holzheimer RG, Mannick JA, editors. Surgical Treatment: Evidence-Based and Problem-Oriented. Munich: Zuckschwerdt; 2001.

3. Meister P, Irmer H, Paul A, Hoyer DP. Therapy of pyogenic liver abscess with a primarily unknown cause. Langenbecks Arch Surg. 2022; 407(6): 2415-2422.

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