Indeterminate, Subcentimetric Focal Liver Lesions in Cancer Patients: Additional Role of Contrast-Enhanced Ultrasound

We read with great interest the article by Laghi et al about the role of contrast-enhanced ultrasound (CEUS) in the characterization of subcentimetric focal liver lesions after a non-specific contrast-enhanced CT (CECT) finding, recently published in Ultraschall in der Medizine [1].

The authors reported that CEUS enabled to reach a correct diagnosis in 43 / 45 cancer patients with subcentimetric indeterminate liver lesions, and our preliminary data strongly agree with such a result (14 out of 16 cases with indeterminate CT findings, unpublished data).

Moreover, in our experience we encountered some cases suggesting that also subcentimetric lesions diagnosed as cystic at CECT should merit to be investigated with CEUS in oncologic patients. [Fig. 1] summarizes the case of a patient with neuroendocrine tumor (NET) of the pancreas accompanied by a 3-mm cystic lesion at CECT ([Fig. 1] a). CEUS was focused at great magnification on the lesion, and enabled to demonstrate enhancement in the arterial phase ([Fig. 1] b) followed by wash-out in the portal venous phase ([Fig. 1] c), allowing the diagnosis of hypervascular metastasis from NET. The diagnosis was then confirmed by surgical exploration.

Fig. 1 a CECT scan of the liver shows a subcapsular 3-mm cystic-like lesion with no vascular signs in the arterial phase (red arrow). b CEUS focused at great magnification on the lesion demonstrates enhancement in the arterial phase (white arrows). c CEUS scan focused on the lesion shows clear wash-out in the portal venous phase.

In the study by Laghi et al, lesions with cystic appearance at preliminary ultrasound (US) examination were ruled out, as further investigations were considered unnecessary.

However, we recently examined a female patient affected by breast cancer, with multiple indeterminate small liver lesions visualized but not characterized by CECT.

Baseline US scans depicted multiple lesions with cystic appearance ranging from 5 to 19 mm in diameter, with the typical anechoic structure and posterior wall reinforce ([Fig. 2] a). Despite the typical cystic appearance, we performed CEUS to definitively confirm the diagnosis, as the patient could not provide any prior imaging documentation of liver cysts. Surprisingly, the lesions showed rapid enhancement in the arterial phase ([Fig. 2] b, right side of the split-screen), followed by wash-out in the portal venous phase ([Fig. 2] c, right side of the split-screen). The CEUS diagnosis of hypervascular metastases was subsequently confirmed by US-guided biopsy.

Fig. 2 a Baseline US scan of the liver shows a 19-mm cystic lesion with the typical anechoic structure and posterior wall reinforce. b CEUS scan of the lesion shows rapid enhancement in the arterial phase (white arrow, right side of the split-screen). c CEUS scan of the lesion shows wash-out in the portal venous phase (white arrow, right side of the split-screen).

Based on this case, in the last months we began to perform CEUS in all neoplastic patients with previously not documented cystic-like focal liver lesions. The usefulness of this approach was supported by another case of ”cystic” liver lesion found in a patient with pancreatic cancer, in which CEUS demonstrated the metastatic nature of the lesion, which was then confirmed by hystologic examination.

In conclusion, we agree with Laghi et al. that subcentimetric liver lesions with CT indeterminate findings should by investigated with CEUS, and we would suggest that also focal liver lesions with cystic appearance at CT or baseline US should undergo CEUS in neoplastic patients, if they were not previously documented. The capability of CEUS to depict the behaviour of a lesion in real-time can add useful information to CECT findings. In our opinion, the unavoidable higher costs of this approach could be counterbalanced by the change of the therapeutic strategy in some cases.

Paola Tombesi

Simona Postorivo
Mirella Catellani

Sergio Sartori
Section of Interventional Ultrasound, Department of Internal Medicine, St. Anna Hospital
44 100 Ferrara
Italy
[e-mail]

References

• 1 Laghi F, Catalano O, Maresca M et al. Indeterminate, sucentrimetric focal liver lesions in cancer patients: additional role of contrast-enhanced ultrasound.  Ultraschall in Med. 2010;  31 283-288