M. Locatelli

Characterization of unifocal liver lesions with pulse inversion harmonic imaging after Levovist injection: preliminary results

Abstract. The aim of this study was to evaluate capabilities of pulse inversion harmonic imaging (PIHI) in characterization of unifocal liver lesions. We evaluated with PIHI (HDI5000, ATL, Bothell, Wash.) and spiral CT 46 consecutive patients with a single liver lesion identified by fundamental US [7 hepatocellular carcinomas (HCC), 2 cholangiocarcinomas, 7 focal nodular hyperplasias (FNH), 17 hemangiomas and 13 metastases]. The PIHI was performed before and 30 s, 2 and 4 min after bolus administration of Levovist (2.5 g, 300 mg/ml). Scans were digitally stored and reviewed using a dedicated software. Hepatocellular carcinoma was hyperechoic on 30-s scan, and hypoechoic (n = 5) or isoechoic (n = 2) on 2-min scan. Cholangiocarcinoma had inhomogeneous persistent enhancement. Focal nodular hyperplasia was hyperechoic (n = 5) or isoechoic (n = 2) on 30-s scan, hyperechoic (n = 4), isoechoic (n = 2) or slightly hypoechoic (n = 1) on 2-min scan. Large hemangioma revealed peripheral enhancement on 30-s scan which extended centripetally on 2-min scan. Small hemangioma appeared isoechoic on 2-min scan in all but two cases in which they were hypoechoic on 2-min scans and hyperechoic on 4-min scan. Metastasis was hypoechoic on all scans, 70 % with rim enhancement. Similar changes in enhancement pattern have been observed at spiral CT.¶ The 30-s and the 2-min scans revealed a conclusive importance in characterization of HCC, cholangiocarcinoma, and large hemangioma. The 2-min scan often furnished enough information for characterization of small hemangioma and metastasis. The 4-min scan allowed characterization of two hemangiomas which appeared hypoechoic on 2-min scans. In the other cases it did not provide further information. Diagnosis of FNH is usually reached with Colour Doppler US; PIHI should be used when colour Doppler is biased by artefacts or when colour Doppler findings are not characteristic. Our results seem to show that PIHI could be a valuable alternative diagnostic approach to spiral CT for unifocal liver lesion characterization. This hypothesis needs to be confirmed with an increased number of lesions.

Characterization of Focal Liver Lesions with Pulse Inversion Harmonic Imaging (PIHI) Using a Second Generation US Contrast Agent

First generation ultrasound (US) contrast agents are made by air microbubbles stabilized by albumin or Dgalactose. Second generation US contrast agents comprise agents made of stabilized microbubbles of gases of high molecular weight and low solubility in water, which provide a higher resistance to US pulse pressure and a longer persistence in the bloodstream than first generation agents (1, 2). Furthermore, the second generation contrast agents have a good harmonic response even at mid and low mechanical index (MI). These features allow an effective evaluation of liver parenchymal enhancement patterns during the different vascular phases as in contrast helical CT (HCT). BR1 (SonoVueTM, Bracco, Milan, Italy) belongs to the second generation of US contrast agents and is based on phospholipid-stabilized sulfur hexafluoride microbubbles (1). BR1 microbubbles circulate in the intravascular space and cross pulmonary and systemic capillary circulation without being trapped, and the gas is easily released in the expired air (3). The aim of this study was to determine whether contrast enhanced Pulse Inversion Harmonic Imaging (PIHI) with BR1 could characterize different focal liver lesions. MATERIALS AND METHODS

Color Doppler sonographic appearance of renal perforating vessels in subjects with normal and impaired renal function

The purpose of this study was to assess the prevalence and color Doppler sonographic characteristics of perforating vessels—small arteries and veins connecting the intrarenal vasculature with the capsular plexus—in healthy subjects, in hypertensive patients, and in patients with renal failure due to hypertensive nephroangiosclerosis or ischemic nephropathy.