实时超声造影与增强螺旋CT检出恶性肿瘤肝转移灶的临床研究

目的 比较常规超声、超声造影及增强CT对恶性肿瘤肝转移灶的检出能力。方法 应用超声造影剂SonoVue及反向脉冲谐波造影成像技术,对73例已确诊为恶性肿瘤并疑有肝转移的患者进行超声造影检查,与常规超声及增强CT结果进行比较。结果 常规超声在67例患者中检出176个转移灶,6例未显示病灶的患者超声造影后检出肝内转移灶,46例患者（63、0％）超声造影较常规超声多检出119个转移灶（P〈0、01）,89、9％的新检出病灶〈2cm,最小者0．3cm。13例患者超声造影较增强CT多检出44个亚厘米转移灶（P〈0．01）,2例患者增强CT较超声造影多检出3个转移灶。结论 超声造影能够明显提高恶性肿瘤肝内小转移灶的检出能力,对亚厘米转移灶的检出优于增强CT,超声造影对恶性肿瘤临床分期及治疗方案的选择有较高的应用价值。     

Diagnosis of gallbladder diseases by contrast-enhanced phase-inversion harmonic ultrasonography

We evaluated the usefulness of contrast-enhanced ultrasonography(US) for detecting and differentiating gallbladder lesions. Contrast-enhanced coded phase-inversion harmonic US was performed on 90 patients with gallbladder abnormalities. After administering Levovist, we observed the gallbladders in real time. Contrast-enhanced coded phase-inversion harmonic ultrasonography was compared with B-mode US and contrast-enhanced computer tomography (CT) with regard to the sensitivity and specificity in depicting the elevated gallbladder lesions. Furthermore, we assessed how the vascular patterns of the elevated gallbladder lesions depicted by contrast-enhanced US correlated with the diagnosis. Contrast-enhanced US efficiently discriminated true lesions from biliary sludge, unlike B-mode US. Consequently, contrast-enhanced US was more specific (100%) than B-mode US (81%), although their sensitivities were similar (98% and 96%, respectively). Contrast-enhanced US was also more sensitive that contrast-enhanced CT (98% versus 79%), although the two methods were equally sensitive (100% versus 95%). We classified the vascular patterns of the abnormalities depicted by contrast-enhanced US in the 90 cases into types 1 to 4, which represent branch-like, heterogeneous, homogeneous, and avascular patterns, respectively. All type 1 and 2 lesions were over 10 mm in size while most (88%) type 3 lesions were 10 mm or less in size. While the majority of carcinomas (86%) were type 1 or 2, three benign lesions also showed these patterns. Thus, the vascular pattern may simply reflect the size of the lesion and therefore its usefulness in diagnosing gallbladder lesions may be limited. Nevertheless, contrast-enhanced US is clearly superior to the other techniques in discriminating biliary sludge from other lesions.     

Detection and differential diagnosis of hepatic masses using pulse inversion harmonic imaging during the liver-specific late phase of contrast enhancement with Levovist

PURPOSE: The purpose of this study was to investigate whether late-phase pulse inversion harmonic imaging (PIHI) increases conspicuity in hepatic masses, helps to differentiate benign from malignant lesions, and demonstrates a greater number of and smaller metastatic lesions than do conventional (fundamental) sonography and helical CT. METHODS: Thirty patients (17 women and 13 men; age range, 35-77 years; mean age, 54 years) with known or suspected liver masses were evaluated using both fundamental sonography and contrast-enhanced PIHI during the liver-specific late phase of Levovist. The patients also underwent contrast-enhanced triphasic helical CT examinations within 1 week after sonography. In 4 of the patients, gadolinium-enhanced MRI was also performed as a part of their clinical work-up. RESULTS: The increase in the lesions' conspicuity on PIHI compared with fundamental sonography was significantly greater in malignant lesions than in benign lesions (p< 0.001). An echogenic rim was observed on PIHI in 8 (53%) of 15 malignant lesions. The mean number of metastatic lesions visualized on PIHI (5.5 +/- 5.3) was significantly higher than the mean number visualized on fundamental sonography (2.5 +/- 2.1, p < 0.05). Although lesions as small as 3 mm were observed on PIHI, the mean sizes of the smallest lesions demonstrated using fundamental sonography, PIHI, and helical CT were not significantly different. CONCLUSIONS: Late-phase PIHI is a useful technique for characterizing hepatic lesions and demonstrating both a greater number of and smaller metastases. It may help to differentiate benign from malignant liver masses and may obviate unnecessary and expensive further imaging.     

Focal hepatic nodules after transcatheter oily chemoembolization; detection with spiral CT versus conventional CT

Background: The objective of this study was to determine if spiral computed tomography (CT) results in increased rate of detection of focal hepatic nodules containing iodized oil after transcatheter oily chemoembolization when compared with conventional CT. Methods: Spiral CT with single 24-s breath-hold technique was compared with conventional sequential CT in 42 patients with suspected hepatocellular carcinomas. Two sets of CT scans obtained after transcatheter oily chemoembolization were independently reviewed by two radiologists. The slice thickness was 10 mm for both data sets. The number and sizes of focal hepatic nodules containing iodized oil were documented. All 42 patients had at least one hepatic nodule. The lesion size varied from 2 mm to 12 cm. Results: In six of the 42 patients, more hepatic nodules could be identified on spiral CT compared with conventional CT. When scans with spiral CT were used, 107 nodules were detected, whereas 98 nodules were detected with conventional CT. Overall, nine (9%) more nodules were detected with spiral CT (<+>p= .002). If lesions larger than 2 cm are excluded, nine (15%) more lesions were detected with spiral CT (<+>p= .002). Conclusion: Spiral CT results in increased rate of detection of focal hepatic nodules after transcatheter oily chemoembolization, particularly in lesions smaller than 2 cm. Received: 11 October 1994/Accepted: 6 November 1994     

Ultrasonographic evaluation of focal hepatic lesions: comparison of pulse inversion harmonic,tissue harmonic,and conventional imaging techniques.

A prospective study was performed to evaluate whether pulse inversion harmonic imaging and tissue harmonic imaging improve the lesion conspicuity and change ultrasonographic characteristics of focal hepatic lesions. Three radiologists evaluated 97 focal hepatic lesions by consensus: cirrhosis‐related nodules (n = 23), metastases (n = 23), hemangiomas (n = 27), and cysts (n = 24). In our study, pulse inversion harmonic imaging was judged superior to both tissue harmonic imaging and conventional imaging in conspicuity and overall quality for cirrhosis‐related nodules, metastases, and cysts (P < 0.05). Compared with conventional imaging, both pulse inversion harmonic imaging and tissue harmonic imaging provided better conspicuity, clearer internal echogenicity, and stronger through‐transmission of cysts (P < 0.05). Pulse inversion harmonic imaging was judged to be better in depicting internal morphology for cirrhosis‐related nodules and metastases than conventional imaging (P < 0.05). For hemangiomas, no statistically significant difference was found in all parameters except better posterior enhancement by tissue harmonic imaging than other techniques. In conclusion, pulse inversion harmonic imaging showed the best conspicuity and also enhanced characteristics of both cystic and solid hepatic lesions. Tissue harmonic imaging was judged superior to conventional imaging in evaluating cysts but was not beneficial for solid lesions. The results of this trial may be specific to the machine used for this study.     

Diagnosis of advanced hepatocellular carcinoma using contrast-enhanced harmonic gray-scale imaging with enhancement agents (Levovist): Correlation with helical CT and US angiography

We compared contrast-enhanced harmonic gray-scale imaging with helical CT and US angiography to evaluate vascularity in advanced hepatocellular carcinoma (HCC). Contrast-enhanced harmonic gray-scale imaging using Levovist (Nihon Schering, Tanabe) as the contrast agent and enhanced helical CT were performed on 38 patients with 45 lesions (29 men and 9 women aged 41 to 83 years; mean age, 66 years; mean maximum tumor diameter, 30.5±23.0 mm), and angiography was performed to evaluate 37 lesions from 32 of these 38 patients (24 men and 8 women, aged 41 to 79 years; mean age, 65 years; mean maximum tumor diameter, 27.9±17.9 mm). Contrast-enhanced harmonic gray-scale imaging showed hypervascular enhancement in 41 of the 45 lesions; the other 4 lesions were not visualized as hypervascular because 3 of the them could not be detected with non-enhanced US and the remaining lesion was situated deep in the liver and more than 11 cm from the surface of the body. Helical CT showed areas of high attenuation in 40 of the 45 lesions, leaving the other 5 lesions equivocal, while US angiography achieved positive enhancement in 36 of 37 lesions. Intratumoral vessels were visualized with contrast-enhanced harmonic gray-scale imaging in 25 of the 45 lesions; however; intratumoral vessels were seen in only 4 of the 45 lesions examined with helical CT. In evaluating vascularity in advanced HCC, contrast-enhanced harmonic gray-scale imaging with Levovist was as effective as US angiography and more effective than helical CT. Motion artifacts produced by the heart make it difficult to evaluate vascularity in advanced HCC located in the left lobe of the liver with Doppler sonography. Contrast-enhanced harmonic gray-scale imaging can show intratumoral vessels and hypervascular enhancement of the tumor without motion artifacts, however, even when the tumor is located near the heart or large vessels. Contrast-enhanced harmonic gray-scale imaging is useful for evaluating vascularity in advanced HCC when the tumor can be visualized with non-enhanced US.     

一种新型声学造影剂对兔肾VX2肿瘤显像的实验研究

目的通过与增强CT对比研究评价本科实验室制作的声学造影剂"脂氟显"对兔肾VX2肿瘤显像的能力.方法 14只左肾种植有VX2肿瘤的家兔,超声造影前和造影后观察肿瘤的大小、数目和能发现的最小肿瘤,在24 h内做CT平扫和增强对照,实验完后处死动物与病理对照.结果 14只兔声学造影后共发现46个肿瘤,增强CT发现的肿瘤数为44个,P值0.336,相关系数r=0.988,病理肿瘤52,与声学造影比较P值0.082,相关系数r=0.978.声学造影能观察到最小肿瘤直径0.32 cm,增强CT发现的最小肿瘤直径0.32 cm,和病理比较无显著性差异.结论脂氟显能有效增强兔肾肿瘤的显像,提高肾脏肿瘤的检出率,与增强CT相当,对肾窦肿瘤优于增强CT.     

The role of late-phase pulse inversion harmonic imaging in the detection of occult hepatic metastases.

OBJECTIVE: The purpose of this study was to investigate the efficacy of late-phase pulse inversion harmonic imaging (PIHI) in detecting occult metastases and to compare the results with helical computed tomography (CT) in a group of patients whose fundamental liver sonographic results were normal. METHODS: Thirty-two patients (21 women and 11 men; age range, 20-87 years) with a known primary malignancy were enrolled in the study. The patients were evaluated with conventional sonography, unenhanced PIHI, and PIHI 3 minutes after the injection of Levovist (SH U 508A; Schering AG, Berlin, Germany). All patients also underwent triphasic helical CT within 1 week after sonography. In 1 patient, mangafodipir-enhanced magnetic resonance imaging was performed as part of the clinical workup. RESULTS: After Levovist injection, in 4 (12.5%) of 32 patients, at least 1 hypoechoic lesion was detected by PIHI; multiple lesions were shown in 1 patient. The mean diameter of newly detected lesions was 12 mm. Triphasic helical CT also showed all of the lesions that were detected by PIHI. The diagnoses were confirmed by biopsy and CT findings in 2 patients and by the typical CT and magnetic resonance imaging findings in 1 patient. For the fourth patient, the diagnosis was confirmed by follow-up and CT. Conclusions. Late-phase PIHI is comparable to helical CT for detecting occult hepatic metastases, but it protects patients from the potentially hazardous effects of radiation and iodinated contrast agents. Further series involving a larger number of patients are needed to determine its place in the evaluation of cancer staging and treatment planning.     

Detection of colo-rectal liver metastases: prospective comparison of contrast enhanced US, multidetector CT, PET/CT, and 1.5 Tesla MR with extracellular and reticulo-endothelial cell specific contrast agents

Background

To compare contrast-enhanced US (CE-US), multidetector-CT (MDCT), 1.5 Tesla MR with extra-cellular (Gd-enhanced) and intracellular (SPIO-enhanced) contrast agents and PET/CT, in the detection of hepatic metastases from colorectal cancer.

Materials and methods

A total of 34 patients with colo-rectal adenocarcinoma underwent preoperatively CE-US, MDCT, Gd- and SPIO-enhanced MR imaging (MRI), and PET/CT. Each set of images was reviewed independently by two blinded observers. The ROC method was used to analyze the results, which were correlated with surgical findings, intraoperative US, histopathology, and MDCT follow-up.

Results

A total of 57 hepatic lesions were identified: 11 hemangiomas, 29 cysts, 1 focal fatty liver, 16 metastases (dimensional distribution: 5/16 < 5 mm; 3/16 between 5 mm and <10 mm; 8/16 ≥ 10 mm). Six of 34 patients were classified as positive for the presence of at least one metastasis. Considering all the metastases and those ≥10 mm, ROC areas showed no significant differences between Gd- and SPIO-enhanced MRI, which performed significantly better than the other modalities (P < 0.05). Considering the lesions <10 mm, ROC areas showed no significant differences between all modalities; however MRI presented a trend to perform better than the other techniques. Considering the patients, ROC areas showed no significant differences between all the modalities; however PET/CT seemed to perform better than the others.

Conclusions

Gd- and SPIO-enhanced MRI seem to be the most accurate modality in the identification of liver metastases from colo-rectal carcinoma. PET/CT shows a trend to perform better than the other modalities in the identification of patients with liver metastases.     

The role of contrast-enhanced ultrasound for focal liver lesion detection: an overview

The development of new ultrasound (US) contrast agents and sonographic techniques has considerably improved the possibilities of ultrasound in the assessment of liver tumors. An overview is given on diagnostic potential of contrast-enhanced US (CEUS) and real-time low mechanical index technique in the detection of various focal liver lesions compared with computed tomography, magnetic resonance imaging or intraoperative US. In two of our own studies that included 100 patients each we showed an increase of correct findings in CEUS compared with B-mode US from 64% to 87% and from 67% to 84% as confirmed by intraoperative evaluation of the liver. Especially after chemotherapy and in the case of small metastases, significantly more metastases were correctly detected by CEUS compared with B-mode US. These results and clinical study results in the literature show that CEUS allows tumor detection and direct visualization of the tumor vascularity and put contrast-enhanced sonography among recommended noninvasive imaging methods for focal liver lesions with improvements in diagnostic strategy.     

Characterization of Focal Liver Lesions with Contrast-Enhanced Ultrasound

The introduction of second generation microbubble ultrasound (US) contrast agents, such as SonoVue (Bracco, Milan, Italy), has considerably improved the diagnostic yield of US imaging for the evaluation of focal hepatic lesions in recent years because of its ability to very sensitively depict tumoral vascularity. In addition, contrast-enhanced US (CEUS) has the advantage of the absence of ionizing radiation, the widespread availability, even at the bedside, and the possibility to characterize a lesion as soon as detected on conventional B-mode US, commonly used as the first technique for exploration of the liver. The present review focuses on the basic principles of the technique and the various patterns of benign and malignant hepatic lesions at CEUS, contributing to their characterization. Understanding of these enhancement features at CEUS according to the type of tumors enables to make more accurate characterization of focal liver lesions as well as give better advice to oncologists, hepatologists or other clinicians in case of suspected liver tumors. (E-mail: fabio.piscaglia@unibo.it)     

Improved imaging of hepatic metastases with delayed pulse inversion harmonic imaging using a contrast agent SH U 508A: preliminary study

To investigate the feasibility of delayed pulse-inversion harmonic imaging (PIHI) with the SH U 508A to improve imaging of hepatic metastases, we evaluated 20 patients with known hepatic metastases. Conventional ultrasound (US) was performed before administration, and PIHI was performed 5 min after a bolus injection of 4 G of microbubble contrast agent (300 mg/mL of SH U 508A). Intense, homogeneous enhancement in the liver parenchyma was seen in all patients on delayed PIHI. In 10 patients (50%), 1 or more focal liver lesions that were not seen on unenhanced imaging were detected on delayed PIHI. When comparing 55 lesions that were seen on both techniques, delayed PIHI was superior to unenhanced imaging in terms of lesion conspicuity and lesion-to-liver contrast (p < 0.001, respectively). Delayed PIHI with SH U 508A can improve conspicuity of hepatic metastases and reveal focal liver lesions that are not detected on unenhanced imaging.     

Significance of hyperattenuating and contrast-enhancing hepatic nodules detected in the cirrhotic liver during arterial phase helical CT in pre-liver transplant patients: radiologic-histopathologic correlation of explanted livers

BACKGROUND: Hyperattenuating nodules detected by arterial phase helical computed tomography (HCT) in patients with cirrhosis usually are believed to represent hepatocellular carcinomas (HCCs). We correlated HCT morphology of hyperattenuating hepatic nodules detected during arterial phase scans with the histopathology of explanted livers of patients with hepatic cirrhosis undergoing liver transplantation. METHODS: Three hundred fifty-four patients had arterial and portal phase HCT performed before subsequent hepatic transplantation. Each patient received 180 mL of contrast by power injection at 5 mL/s. All hyperattenuating nodules detected on arterial phase HCT were assessed for morphology and evidence for contrast enhancement. Explanted livers in all patients were then sectioned at 10-mm intervals, and the histology of the nodules was correlated with the HCT findings. RESULTS: Sixty-one hyperattenuating nodules were detected on the arterial phase HCT in 43 patients: 41 nodules were benign regenerating nodules (RN), three were dysplastic nodules (DP), and 17 were HCCs. Most RN/DP nodules were 5-20 mm in diameter, had distinct margins, were homogeneous, and were isoattenuating on precontrast, portal, and delayed scans. Thirty-six showed positive contrast enhancement and displayed a wide range of attenuation profiles. HCC nodules were 6-50 mm. All showed positive contrast enhancement and displayed a wide range of attenuation profiles. CONCLUSION: Hyperattenuating nodules seen on arterial phase HCT are likely to be RN/DP nodules. In many cases, it is not possible to distinguish between RN/DP and HCC. Thus, clinical decisions regarding inclusion criteria for transplantation based on CT morphology of liver lesions may be tenuous.     

Improved visualization of high-intensity focused ultrasound lesions

Spectral parameter imaging in both the fundamental and harmonic of backscattered radio-frequency (RF) data were used for immediate visualization of high-intensity focused ultrasound (HIFU) lesion sites. A focused 5-MHz HIFU transducer with a coaxial 9-MHz focused single-element diagnostic transducer was used to create and scan lesions in chicken breast and freshly excised rabbit liver. B-mode images derived from the backscattered RF signal envelope were compared with midband fit (MBF) spectral parameter images in the fundamental (9-MHz) and harmonic (18-MHz) bands of the diagnostic probe. Images of HIFU-induced lesions derived from the MBF to the calibrated spectrum showed improved contrast (approximately 3 dB) of tumor margins versus surround compared with images produced from the conventional signal envelope. MBF parameter images produced from the harmonic band showed higher contrast in attenuated structures (core, shadow) compared with either the conventional envelope (3.3 dB core; 11.6 dB shadow) or MBF images of the fundamental band (4.4 dB core; 7.4 dB shadow). The gradient between the lesion and surround was 3.4 dB/mm, 6.9 dB/mm and 17.2 dB/mm for B-mode, MBF-fundamental mode and MBF-harmonic mode, respectively. Images of threshold and "popcorn" lesions produced in freshly excised rabbit liver were most easily visualized and boundaries best-defined using MBF-harmonic mode.     

螺旋CT双期动态扫描对肝转移瘤的诊断价值

目的:探讨肝转移瘤双期动态增强扫描的CT征象。方法:应用螺旋CT对67例肝转移瘤病人分别进行平扫、增强后肝动脉期和门静脉期扫描,观察瘤灶双期动态扫描的CT征象。结果:(1)67例中29例肝动脉期瘤灶边缘部出现环形强化,其强化密度高于正常肝,低于主动脉。门静脉期瘤灶边缘部的环形强化范围不扩大,其中27例密度仍可高于或等于正常肝,2例密度低于正常肝。(2)67例中22例肝动脉期和门静脉期瘤灶边缘部和瘤内均无明显强化,密度低于正常肝。(3)67例中7例肝动脉期瘤灶出现全瘤均匀性或不均匀性强化,密度高于正常肝;门静脉期瘤灶密度下降,密度等于或低于正常肝。(4)67例中8例肝动脉期多发的肝转移瘤中,一部分瘤灶出现全瘤均匀性或不均匀性强化,或边缘部环形强化,密度高于正常肝;门静脉期密度下降至等于或低于正常肝。另一部分瘤灶则动、门脉双期均始终未见强化。结论:肝转移瘤CT双期动态增强扫描的主要征象是:(1)动脉期瘤灶边缘部出现密度高于正常肝的环形强化,门静脉期此环形强化范围无扩大,密度仍高于或等于正常肝。(2)双期扫描瘤灶均无强化,呈低密度。(3)双期扫描部分瘤灶强化,另一部分瘤灶则始终未见强化。     

Evaluation of the accuracy of articular cartilage thickness measurement by B-mode ultrasonography with conventional imaging and real-time spatial compound ultrasonography imaging

The present study aimed to quantify the thickness of articular cartilage (Tc) in vitro using both conventional and real-time spatial compound B-mode ultrasonography (US) with a clinically used transducer and to evaluate the accuracy of measurement by comparing the results with values obtained microscopically. Femoral condyle samples were obtained from a 6-month-old pig and a 3-year-old pig. B-mode US images with conventional imaging and real-time spatial compound imaging (RTSCI) of osteochondral blocks were acquired. Tc determined using US (Tc-US) was measured from line data parallel to US beam direction acquired from B-mode images with an objective method for determining cartilage surface and bone-cartilage interfaces at the peak brightness values. Tc was also determined under microscopy (Tc-optical) using the corresponding points from US measurement. Tc-US was compared with Tc-optical to assess accuracy. Tc-US correlated significantly with Tc in both conventional imaging and RTSCI (r = 0.961, 0.976, respectively). Bland-Altman plots showed mean differences between Tc-optical and Tc-US were -0.0073 mm and 0.0139 mm with standard deviations of 0.171 mm and 0.131 mm for conventional imaging and RTSCI, respectively. Our results show that Tc-US measurement using B-mode US allows accurate measurement of Tc. Considering correlation coefficients between Tc-US and Tc-optical, RTSCI US may offer higher accuracy for measuring Tc than conventional methods when an objective tissue border determination algorithm is used, even though both showed good accuracy in our study.     

肝局灶性结节性增生的超声和CT对照分析

目的 探讨肝局灶性结节性增生（FNH）的超声和CT表现及其诊断价值。方法 15例住院病例行超声与CT检查。结果 15例FNH均经手术及病理证实,共有16个病灶,其中右叶9个,左叶6个,尾叶1个,B超和CT均全部检出,B超多表现为低或略低回声（88%）,可有浅淡暗环（44%）;彩色多普勒显示有粗大血管进入病灶内并分支（81%）,可呈轮辐状血流（19%）,脉冲多普勒均测及动脉血流,阻力指数平均为0.54。CT表现为病灶增强后,早期明显强化（100%）,星状疤痕显示率为44%,门静脉期及延迟扫描多呈等密度（75%）,常规B超联合彩色多普勒超声诊断FNH的符合率为50%;CT诊断FNH的符合率为50%。结论 常规超声联合彩色多普勒超声和CT增强结合动脉扫描可提高FNH的诊断准确性。     

Significance of hyperattenuating and contrast-enhancing hepatic nodules detected in the cirrhotic liver during arterial phase helical CT in pre–liver transplant patients: radiologic–histopathologic correlation of explanted livers

Background: Hyperattenuating nodules detected by arterial phase helical computed tomography (HCT) in patients with cirrhosis usually are believed to represent hepatocellular carcinomas (HCCs). We correlated HCT morphology of hyperattenuating hepatic nodules detected during arterial phase scans with the histopathology of explanted livers of patients with hepatic cirrhosis undergoing liver transplantation. Methods: Three hundred fifty-four patients had arterial and portal phase HCT performed before subsequent hepatic transplantation. Each patient received 180 mL of contrast by power injection at 5 mL/s. All hyperattenuating nodules detected on arterial phase HCT were assessed for morphology and evidence for contrast enhancement. Explanted livers in all patients were then sectioned at 10-mm intervals, and the histology of the nodules was correlated with the HCT findings. Results: Sixty-one hyperattenuating nodules were detected on the arterial phase HCT in 43 patients: 41 nodules were benign regenerating nodules (RN), three were dysplastic nodules (DP), and 17 were HCCs. Most RN/DP nodules were 5–20 mm in diameter, had distinct margins, were homogeneous, and were isoattenuating on precontrast, portal, and delayed scans. Thirty-six showed positive contrast enhancement and displayed a wide range of attenuation profiles. HCC nodules were 6–50 mm. All showed positive contrast enhancement and displayed a wide range of attenuation profiles. Conclusion: Hyperattenuating nodules seen on arterial phase HCT are likely to be RN/DP nodules. In many cases, it is not possible to distinguish between RN/DP and HCC. Thus, clinical decisions regarding inclusion criteria for transplantation based on CT morphology of liver lesions may be tenuous.     

Liver metastases in cancer: detection with contrast-enhanced ultrasonography

In patients with known or suspected malignancy, ultrasonography (US) is often the first choice for liver imaging because of its widespread availability and low cost. Compared with contrast-enhanced computed tomography (CT) and magnetic resonance imaging (MRI), the sensitivity of conventional US for detecting hepatic metastases is relatively poor. The advent of microbubble contrast agents changed this situation. Sensitivity and specificity increased substantially with the use of these contrast agents and contrast-specific imaging modes in recent years. Currently, numerous US imaging methods exist, based on Doppler techniques or harmonic imaging. They exploit the complex nonlinear behavior of microbubbles in a sound field to achieve marked augmentation of the US signal. Although microbubble contrast agents are essentially blood pool agents, some have a hepatosplenic specific late phase. Imaging during this late phase is particularly useful for improving the detection of malignant liver lesions and allows US to perform similarly to spiral CT as shown by recent studies. In addition, this late phase imaging is very helpful for lesion characterization. Low mechanical index imaging with the newer perfluor agents permits real-time imaging of the dynamic contrast behavior during the arterial, portal venous, and late phases and is particularly helpful for lesion characterization. The use of US for hemodynamic studies of the liver transit time may detect blood flow changes induced by micrometastases even before they become visible on imaging. In this field of functional imaging, further research is required to achieve conclusive results, which are not yet available.