Type:
Educational Exhibit
Keywords:
Liver, Abdomen, CT, Ultrasound, MR, Contrast agent-intravenous, Abscess, Infection
Authors:
D. Sergi1, M. Di Pietropaolo1, F. Tavanti1, C. De Vincentiis2, C. Bernardi2, C. Briani1, I. Matarazzo3, A. Speranza4, V. David1; 1Rome/IT, 2Roma/IT, 3Tomba di Nerone (RM)/IT, 4Roma, RM/IT
DOI:
10.1594/ecr2013/C-1395
Imaging findings OR Procedure details
Ultrasound and computed tomography are the first line imaging modalities; in the next step,
MRI is useful in the detection of small differences in tissue composition in fungal infection due to multiplanar capability and excellent contrast resolution.
Candidal liver disease is usually characterize by microabscess and granulomas,
in contrast large abscess are rare [4].
Four patterns of US findings of liver fungal abscesses have been observed,
correlating to the stage of the disease: the most common pattern is the least specific appearance of liver abscesses and consists of uniform hypoechoic nodule; the second pattern also known as “bull’s-eye configuration” consists of a central echogenic nidus with a hypoechoic rim,
which is usually seen in active infection.
The “wheel-within wheel” appearance is the third pattern described and consists of a central hypoechoic area of necrosis and fungi,
surrounded by an echogenic zone of inflammatory cells and a hypoechoic rim due to fibrosis (fig.1).
In later stages of infection is often seen the fourth pattern: echogenic lesion with variable degrees of posterior acoustic shadowing indicating early resolution [4,5].
At CT fungal abscesses usually appear as multiple round,
hypodense lesions with centrally or rim enhancement after intravenous administration of contrast agent (fig.
2-4).
The “wheel within wheel” pattern,
typical of early disease,
is usually not seen at CT imaging,
whereas the “bull’s eye” pattern is seen occasionally [1].
At MRI the untreated abscesses appear as nodule iso-hypointense on T1 weighted images (WI) before and after gadolinium administration and markedly hyperintense on T2WI.
After initial treatment,
lesions appear moderately hyperintense with hypointense ring on T1WI and T2WI (fig.5),
showing enhancement on gadolinium-enhanced T1WI (fig.6-8).
Completely treated lesions are minimally hypointense on T1WI,
iso-hyperintense on T2WI,
hypointense on arterial phase and minimally hypointense on equilibrium phase images [4].
Previously studies have suggested that CT is superior to US in the characterization of fungal liver abscesses and that dynamic contrast-enhanced MR imaging is better to dynamic contrast-enhanced CT imaging especially in the evaluation of treatment progression [1,6].