Percutaneous liver microwave ablation of caudate lobe lesion

Case contributed by Umberto Pisano

Presentation

Prior hepatitis C infection, cleared. Detection of hyperechoic lesion on US in central liver. Patient asymptomatic. Good performance status (ECOG1). Child-Pugh A.

Patient Data

Age: 60 years
Gender: Female

The incidental lesion was then further characterized and kept under surveillance with MRI.

Liver MR with contrast

mri

Pre- (axial T2, in- and out-of-phase T1) and post-contrast (arterial, portal venous and 2 minutes delayed) sequences demonstrate a moderately T2 hyperintense, fat-containing lesion in the caudate lobe. Allowing for respiratory artefacts, there is a degree of enhancement within the lesion, better appreciated on portal venous and delayed imaging. No appreciable arterial perfusion. No restriction on DWI (not shown), no signal on hepatobiliary phase (not shown).

No other focal liver observations. Patent portal vein.

Generally heterogeneous liver signal suspicious for fibrosis, some enlargement of the caudate lobe but no clear cirrhotic contour.

While the appearances had a not clearly malignant imaging phenotype, progressive growth was seen over time. Given patient's anxiety and uncertainty of diagnosis, curative locoregional treatment was favored in MDT settings. The chosen modality was CT-guided percutaneous biopsy and microwave ablation.

Intra-operative CT imaging

ct

Our chosen protocol consists of arterial, portal venous (not shown) and delayed (not shown) volumes through the liver. Microwave needle placement is carried out with fluoroscopic assistance, using low dose 4mm slices with no overlap.

In this particular case, a 17Ga x 6.8cm long coaxial system was placed to allow sampling of the lesion using a 18Ga x 10cm long Argon Biopince device. The lesion was then ablated effectively with two ablation cycles, deep and superficial, at 120W for two minutes, using a Solero Angiodynamics machine (operating frequency 2.45GHz).

Selected images demonstrate the lesion being traversed by the biopsy device, and the microwave needle (15Ga x 19cm long) within the index observation. The following post-ablation arterial phase shows the original fatty lesion surrounded by an adequate ablation zone with florid hyperemia; satisfactory coverage is confirmed with a 'volume matching' reconstruction, by superimposing pre- and post-ablation volumes (final selected image).

Small amount of hemoperitoneum after ablation, of no clinical consequence. Note also made of cholelithiasis.

Case Discussion

The pathology result reported on markedly steatotic and nodular tissue: the main differential diagnosis being between a dysplastic nodule as well as macro-regenerative nodule (a hepatocellular carcinoma being considered unlikely). A background of liver fibrosis was described.

No sign of tumor viability was seen on further follow up imaging: the patient was discharged to the referring hepatology team for routine surveillance.

Image-guided tumor ablation is a well recognized locoregional treatment for hepatocellular carcinoma and metastatic deposits1. While data comparing different ablation technique is somewhat limited and sometimes discordant, microwave ablation (MWA) is a very effective technique with similar efficacy to surgical resection2. When compared to radiofrequency ablation (RFA), MWA does not require grounding pads, is able to achieve higher tissue temperatures, and typically requires shorter ablation cycles. 

MWA is now preferred over RFA at many institutions.

The submitter has no disclosure to make.

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