Alveolar echinococcosis of the liver: diffusion-weighted MRI findings and potential role in lesion characterisation.
OBJECTIVE
To report the diffusion-weighted MRI findings in alveolar echinococcosis (AE) of the liver and evaluate the potential role of apparent diffusion coefficients (ADCs) in the characterisation of lesions.


METHODS
We retrospectively included 22 patients with 63 AE liver lesions (≥1 cm), examined with 3-T liver MRI, including a free-breathing diffusion-weighted single-shot echo-planar imaging sequence (b-values=50, 300 and 600 s/mm(2)). Two radiologists jointly assessed the following lesion features: size, location, presence of cystic and/or solid components (according to Kodama's classification system), relative contrast enhancement, and calcifications (on CT). The ADC(total), ADC(min) and ADC(max) were measured in each lesion and the surrounding liver parenchyma.


RESULTS
Three type 1, 19 type 2, 17 type 3, three type 4 and 21 type 5 lesions were identified. The mean (±SD) ADC(total), ADC(min) and ADC(max) for all lesions were 1.73 ± 0.50, 0.76 ± 0.38 and 2.63 ± 0.76 × 10(-3)mm(2)/s, respectively. The mean ADC(total) for type 1, type 2, type 3, type 4 and type 5 lesions were 1.97 ± 1.01, 1.76 ± 0.53, 1.73 ± 0.41, 1.15 ± 0.42 and 1.76 ± 0.44 × 10(-3)mm(2)/s, respectively. No significant differences were found between the five lesion types, except for type 4 (p=0.0363). There was a significant correlation between the presence of a solid component and low ADCmin (r=0.39, p=0.0016), whereas an inverse correlation was found between the relative contrast enhancement and ADCtotal (r=-0.34, p=0.0072).


CONCLUSIONS
The ADCs of AE lesions are relatively low compared to other cystic liver lesions, which may help in the differential diagnosis. Although ADCs are of little use to distinguish between the five lesion types, their low value reflects the underlying solid component.
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Rue du Bugnon 46, 1011 Lausanne, Switzerland.
Fabio
F
Becce
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Rue du Bugnon 46, 1011 Lausanne, Switzerland.
Anastasia
A
Pomoni
Department of Visceral Surgery, Lausanne University Hospital, Rue du Bugnon 46, 1011 Lausanne, Switzerland.
Emilie
E
Uldry
Department of Visceral Surgery, Lausanne University Hospital, Rue du Bugnon 46, 1011 Lausanne, Switzerland.
Nermin
N
Halkic
University Institute of Pathology, Lausanne University Hospital, Rue du Bugnon 25, 1011 Lausanne, Switzerland.
Pu
P
Yan
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Rue du Bugnon 46, 1011 Lausanne, Switzerland.
Reto
R
Meuli
Department of Diagnostic and Interventional Radiology, Lausanne University Hospital, Rue du Bugnon 46, 1011 Lausanne, Switzerland. Electronic address: sabine.schmidt@chuv.ch.
Sabine
S
Schmidt
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D004444:Echinococcosis, Hepatic / Q000473:pathology*; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
Alveolar echinococcosis; Apparent diffusion coefficient (ADC); Diffusion-weighted MRI (DWI); Liver; Magnetic resonance imaging (MRI); Parasites