Korean J Radiol.  2003 Jun;4(2):91-100. 10.3348/kjr.2003.4.2.91.

Focal Hepatic Lesions: Evaluation with Contrast-Enhanced Gray-Scale Harmonic US

• Jang HJ
• Lim HK
• Lee WJ
• Kim SH
• Kim MJ
• Choi D
• Lee SJ
• Lim JH

• KMID: 1118811
• DOI: http://doi.org/10.3348/kjr.2003.4.2.91

Abstract

OBJECTIVE
To determine the findings of various focal hepatic lesions at contrast-enhanced gray-scale ultrasound (US) using a coded harmonic angio (CHA) technique and emphasizing lesion characterization. MATERIALS AND METHODS: The study involved 95 patients with 105 focal hepatic lesions, namely 51 hepatocellular carcinomas (HCCs), 22 metastases, 22 hemangiomas, four cases of focal nodular hyperplasia (FNH), and six nontumorous nodules. After the injection of a microbubble contrast agent (SH U 508A), gray-scale harmonic US studies using a CHA technique were performed with a combination of continuous scanning to assess the intratumoral vasculature (vascular imaging) and interval-delay scanning to determine the sequential enhancement pattern (acoustic emission imaging). Each imaging pattern was categorized and analyzed. RESULTS: At vascular imaging, 69% of HCCs (35/51) showed irregular branching vessels, while in 91% of metastases (20/22) a peripherally stippled pattern was observed. Intratumoral vessels were absent in 95% of hemangiomas (21/22) and all nontumorous lesions (6/6), while in 75% of FNHs (3/4) a spoke-wheel pattern was evident. At acoustic emission imaging, 71% of HCCs (36/51) showed heterogeneous enhancement and 86% (19/22) of metastases showed rim- or flame-like peripheral enhancement during the early phase, with washout occurring in all HCCs and metastases (100%, 73/73) during the late phase. In hemangiomas, enhancement was either peripheral and nodular (19/22, 86%) or persistent and homogeneous (3/22, 14%), and 75% of FNHs (3/4) became isoechoic during the late phase. CONCLUSION: At contrast-enhanced gray-scale US using a CHA technique, a period of continuous scanning depicted the intratumoral vasculature, and interval-delay scanning demonstrated the sequential enhancement pattern. The characteristic findings of various focal hepatic lesions were thus determined.

Keyword

Liver neoplasms, US; Ultrasound (US), contrast media; Ultrasound, harmonic study; Ultrasound, technology

Figure

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  Fig. 1 The intratumoral vascular patterns seen during vascular phase imaging.

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  Fig. 2 Two characteristic vascular patterns of HCC (arrows). A. Irregular branching pattern. B. Randomly stippled pattern.

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  Fig. 3 HCC (arrows). Serial acoustic emission images obtained at 20-sec (A), 2-min (B), and 5-min (C) delay show early enhancement (A) and heterogeneous washout (B, C).

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  Fig. 4 Metastasis from duodenal carcinoma. Serial acoustic emission image depicts rim-or flame-like enhancement during the early phase (A, 40-sec delay) and a homogeneous perfusion defect during a later phase (B, 5-min delay).

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  Fig. 5 Hemangioma. Serial CHA acoustic emission images obtained during the precontrast phase (A), and at 20-sec (B), 1-min (C), and 5-min (D) delay, clearly demonstrate typical peripheral nodular enhancement with progressive centripetal fill-in.

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  Fig. 6 Unusual hemangioma with arterioportal shunt (A, precontrast; B, 20-sec delay; C, 42-sec delay; and D, 5-min delay). Only 20 sec after injection (B), CHA vascular phase imaging shows an early draining portal vein (arrows) and intratumoral vascular stippling. However, persistent homogeneous enhancement until 5-minute delay (D) led to the correct diagnosis.

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  Fig. 7 FNH (arrows). CHA images clearly depict the typical spoke-wheel pattern seen during the early vascular phase (A, 40-sec delay). The mass becomes isoechoic at late acoustic emission imaging (B, 3-min delay), a tendency which may help differentiate FNH from some HCCs showing a similar spoke-wheel vascular pattern but a washout pattern at late acoustic emission imaging.

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  Fig. 8 Focal fatty lesion in a breast cancer patient. Portal venous phase CT (A) shows a target-like hepatic nodule (arrow). At CHA vascular phase imaging (B, 40-sec delay), no vascular pattern is observed (arrows), and during both other phases of acoustic emission imaging (C, 3-min delay; D, 5-min delay), the lesion is completely obscured; its enhancement is the same as that of surrounding parenchyma. Subsequent MR imaging using the fat suppression technique (not shown) confirmed the diagnosis of focal fat deposition.

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  Fig. 9 Inflammatory nodule in a rectal cancer patient. Portal venous phase CT (A) shows a hypoattenuating mass (arrow). CHA vascular phase imaging (B, 40-sec delay) reveals no vascular pattern within the mass (arrows), which appears as a perfusion defect at both other phases of acoustic emission imaging (C, 2-min delay; D, 5-min delay). Biopsy revealed chronic inflammation and necrosis.

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