Sonography with intraarterial infusion of carbon dioxide microbubbles (sonographic angiography): value in differential diagnosis of hepatic tumors

Intra-arterial carbon dioxide-enhanced ultrasonogram of hepatocellular carcinoma treated by transcatheter arterial embolization and percutaneous ethanol injection therapy

The purpose of this study was to investigate the value of carbon dioxide-enhanced ultrasonography (CO2-US) in the evaluation of viable hepatocellular carcinomas (HCC) which were treated by transcatheter arterial embolization (TAE), percutaneous ethanol injection (PEI), or a combination treatment (TAE and PEI). Forty-one patients with 66 HCC were included in the study. They underwent CO2-US and angiography were performed in all tumours after they were treated by TAE, PEI or a combination treatment. Forty-six tumours were positively enhanced by CO2-US and 40 of them were positive by angiography. These 46 tumours were proved to be viable tumours either by biopsy or by follow-up studies. The positive predictive value was 100% for CO2-US and 87.8% in angiography. Twenty tumours were negative by CO2-US and these were also negative by angiography. Carbon dioxide-enhanced ultrasonography is a more reliable method for detecting the viable portion of the treated HCC compared with conventional angiography.

Usefulness of novel imaging modalities in diagnosis of focal nodular hyperplasia of the liver

A 17-year-old woman was admitted because of a liver tumor found incidentally by ultrasonography. Liver function was normal and there were no markers of hepatitis viruses or malignancy. Abdominal ultrasonography, computed tomography (CT), and magnetic resonance imaging revealed a mass (2 cm in diameter) in the lateral segment of the left lobe of the liver. The lesion was not detected by hepatic arteriography. However, dynamic CT with fast scanning and dynamic CO2-enhanced ultrasonography demonstrated initial central enhancement of the mass followed by centrifugal spread of enhancement to the periphery. Color Doppler flow imaging detected a central color spot, shown to be an artery by a pulsed Doppler spectrum analysis. Fine-needle biopsy confirmed a diagnosis of focal nodular hyperplasia. Dynamic CT with fast scanning, dynamic CO2-enhanced ultrasonography, and color Doppler flow imaging were useful in detecting the vascular pattern specific to focal nodular hyperplasia. Investigation of further cases with these novel imaging modalities should help to establish a comprehensive diagnostic procedure and thus avoid unnecessary surgery for focal nodular hyperplasia, which is a completely benign lesion.

Clinical experience with sonographic contrast agents

Early generations of sonographic contrast agents are beginning to reach the attention of the clinician. Research and development of ultrasound contrast agents is progressing at a rapid pace with several new agents approaching US Food and Drug Administration approval. Cardiac imaging has been affected by even the limited availability of contrast agents on the market today both with regard to diagnosis of shunts and chamber opacification, and most recently actual enhancement of the myocardium. Later generations of contrast are capable of providing consistent opacification of both peripheral veins and arteries, and should prove useful in a variety clinical applications. Thus far, it appears that longer vessel segments may be seen with contrast rather than without contrast, and that flow may be demonstrated in vessels which were not seen or thought to be occluded with conventional color imaging. Improved detection of arterial and venous collaterals and enhanced identification of run-off vessels is demonstrated with sonographic contrast agents. An improved ability to evaluate renal artery stenosis and subtotal occlusion of the carotid artery are specific advantages of using contrast as well. Several compounds are currently being tested that may allow routine parenchymal opacification. Ultrasound is the most commonly performed diagnostic imaging procedure; therefore, contrast agents have the potential to dramatically alter the practice of clinical medicine. This article reviews the current status of ultrasound contrast agents and speculates regarding the future applications of these agents.

Doppler ultrasound in the evaluation of cirrhotic patients: the prevalence of intrahepatic arteriovenous shunting, and implications for diagnosis of hepatocellular carcinoma

To establish the prevalence and significance of Doppler-detected hepatic arteriovenous shunting (AVS) in patients with compensated cirrhosis, 115 patients (mean age 55.4 +/- 12.47 SD y) were prospectively screened using real-time ultrasound with pulsed Doppler at 2.5 MHz to detect focal liver lesions and quantify AVS. Focal masses were biopsied and correlated with the US findings. All other patients had clinical follow-up and imaging for at least 12 months. AVS occurred in 28 of 115 (24.3%), and in 18 of 20 proven malignancies (90%) including 11 of 13 cases of hepatocellular carcinoma (85%). However, 9 of 28 (32%) AVS (mean Doppler shift 2.73 +/- 1.51 [SD] kHz [range 0.6-5.41 kHz], n = 9) were in regions of fatty infiltration (4) or isolated (5), unassociated with malignancy. At a prevalence of 17.9% malignancy (11.3% due to hepatocellular carcinoma), specificity for malignancy increased with shunt velocity, from 76% (for mass alone), to 94.8% for mass with AVS, 96.8% for a mass with AVS of 1.75-2.4 kHz, and 100% for a mass with AVS > 2.4 kHz. Doppler US is useful in characterizing liver lesions in cirrhotic patients: the majority of malignant hepatic lesions are associated with AVS and specificity for malignancy increases with shunt velocity. However, isolated AVS or AVS associated with focal fat may be detected in 7.8% of compensated cirrhotics.

Iodized-oil retention within hepatic hemangioma: characteristics on iodized-oil CT

OBJECTIVE

The purpose of this study was to describe the characteristic computed tomographic (CT) appearance of iodized-oil retention in hepatic hemangioma and to evaluate the duration of the retention of iodized oil on follow-up CT.

METHODS

Seventeen hepatic hemangiomas of 14 patients were studied with CT performed 1-3 weeks after injection of 2-9 ml of iodized oil (iodized-oil CT) for the characterization of focal hepatic lesions, which needed differential diagnosis with hepatocellular carcinoma in 10 patients, for therapy in two patients, and for chemoembolization therapy of accompanying hepatocellular carcinomas in two. Twelve patients had 1-7 follow-up CT scans within an interval of 1-38 months.

RESULTS

In all cases, iodized-oil CT showed iodized-oil retention within the tumor, regardless of tumor size, shape, location, and amount of injected iodized oil. The distribution was incomplete and predominantly peripheral in all cases. Central retention was also seen in seven cases, in which a relatively large amount of iodized oil was injected, but retention of iodized oil in the tumor was incomplete even in two cases in which a large amount of iodized oil was injected to relieve symptoms and in three cases in which prominent uptake of surrounding liver parenchyma was seen. Patterns of retention were predominantly spotty in five, predominantly nodular in four, and mixed in eight patients. Retention materials slowly washed out but persisted for at least 3 months and up to 38 months (mean = 18.1 months), and complete washout was not seen in any cases at follow-up CT.

CONCLUSION

In all cases of hepatic hemangiomas, iodized oil was retained, and retention persisted over several months. Distribution and patterns of retention were characteristically peripheral, spotty, and nodular at iodized-oil CT. Knowledge of the iodized-oil CT appearance of hepatic hemangioma would be helpful to interpret follow-up CT studies of patients who have undergone iodized-oil chemoembolization procedures.

Detection of hepatocellular carcinoma by intraarterially enhanced ultrasonography with CO2 microbubbles. Comparison with DSA, dynamic CT, and Lipiodol CT

PURPOSE

To evaluate the diagnostic value of contrast-enhanced US with CO2 microbubbles (EU) for HCCs. Detectability was compared with DSA, dynamic CT, and Lipiodol CT.

MATERIAL AND METHODS

Forty-seven histologically proven HCCs detected with US were evaluated with EU, DSA, and dynamic CT. In 23 patients (35 lesions), Lipiodol CT was also performed. The size of the tumors ranged from 8 to 71 mm (average 28.1 mm); 24 lesions were smaller than 20 mm and 23 lesions were larger than 20 mm.

RESULTS

Overall detection was possible in 40 of 47 lesions (85%) by EU, in 32 of 47 (68%) by DSA, in 33 of 47 (74%) by dynamic CT, and in 27 of 35 (77%) by Lipiodol CT. In tumors smaller than 20 mm, detection was possible in 21 of 24 lesions (88%) by EU, 14 of 24 (58%) by DSA, 14 of 24 (58%) by dynamic CT, and 11 of 17 (65%) by Lipiodol CT.

CONCLUSION

EU has significant diagnostic value for detection of HCCs, particularly tumors smaller than 20 mm.

Detection and characterization of hepatocellular carcinoma: value of dynamic CT during the arterial dominant phase with uniphasic contrast medium injection

OBJECTIVE

Our goal was to assess the effect of dynamic CT during the arterial dominant phase with uniphasic injection of intravenous contrast material (5 ml/s) in the detection and characterization of hepatocellular carcinomas (HCCs).

MATERIALS AND METHODS

Three-phase incremental dynamic CT was performed in 66 patients with 84 HCCs diagnosed by pathologic findings, characteristic angiographic findings, and clinical manifestations. One hundred fifty milliliters of nonionic contrast medium was administered intravenously by using a power injector at a flow rate of 5 ml/s for 30 s, and three-phase images were obtained at 20-45 s (arterial dominant phase), 55-80 s (portal venous phase), and 2-4 min (equilibrium phase) after the start of uniphasic intravenous injection. Three-phase images in 66 patients were compared and assessed for the detectability and enhancement pattern of the tumors.

RESULTS

The arterial dominant phase images of dynamic CT showed a moderate to marked hyperattenuation in 73 (87%) of the 84 HCCs, isoattenuation in 6 (7%), and hypoattenuation in 5 (6%). The portal venous phase images showed hyperattenuation in 6 (7%), isoattenuation in 45 (54%), and hypoattenuation in 33 (39%). In the equilibrium phase, CT findings showed hypoattenuation in 67 (80%) and isoattenuation in 17 (20%). The detectability of HCCs in the arterial dominant, portal venous, and equilibrium phase was 93, 46, and 80%, respectively. The detectability of HCCs in the arterial dominant phase was significantly (p < 0.0001) superior to that in both the portal venous phase and the equilibrium phase.

CONCLUSION

Dynamic CT during the arterial dominant phase with uniphasic injection of intravenous contrast medium (5 ml/s) is a useful method in the detection and characterization of HCCs.

Hepatic focal nodular hyperplasia: colour Doppler ultrasound can be diagnostic

Focal nodular hyperplasia (FNH) is a rare, benign, hepatic mass lesion that is usually found in young adult females. It is sometimes an incidental finding on abdominal sonography or computed tomography. Its appearance on these studies is not characteristic however, thereby creating a diagnostic problem. This report is of a case which showed a centrifugal, spokewheel pattern of pulsatile blood supply on colour Doppler US. This finding, we suggest, is sufficiently diagnostic to avoid the need for further investigation in some patients, and to direct further imaging more appropriately in others.

Serial hemodynamic measurements in well-differentiated hepatocellular carcinomas

We performed serial hemodynamics in 15 patients with 21 well-differentiated hepatocellular carcinomas. The total length of the observation period ranged from 129 to 678 days (median, 368). We investigated both arterial and portal blood flow at intervals of at least 4 months. Arterial blood flow was measured with carbon dioxide-enhanced ultrasonography (US), and portal blood flow was measured with computed tomographic arterial portography (CTAP). None of the tumors were hypervascular on the initial study; however, by the final study nine nodules (42.9%) had become homogeneously hypervascular, two (9.5%) had become partially hypervascular, and the others did not change. Of 10 nodules without portal blood supply on any study, 8 became hypervascular by the final study. Of 11 nodules with portal blood supply on the initial study, a follow-up study showed no change in portal flow in 6 and the loss of portal flow in 5. Four of these five became hypervascular, with a documented loss of portal flow before the increase in arterial flow. The doubling time of tumors with a homogeneous increase in arterial blood flow ranged from 89 to 333 days (median, 172), whereas the doubling time of other tumors ranged from 227 to 607 days (median, 392). Thus, growth rate and vascularity in well-differentiated hepatocellular carcinoma are closely correlated. When the well-differentiated hepatocellular carcinoma has portal blood flow and is not hypervascular, it grows slowly. On the other hand, when it loses portal blood flow and becomes hypervascular, it grows rapidly.

Intraoperative microwave tissue coagulation as treatment for patients with nonresectable hepatocellular carcinoma

BACKGROUND

The microwave tissue coagulator (2450 MHz) has been used clinically in the treatment of hepatocellular carcinoma (HCC) to transection of the liver parenchyma and has proven an excellent method for hemostasis. There are, however, few reports on the application of this coagulator to the induction of tumor necrosis.

METHODS

Microwave tissue coagulation (MTC) was applied at laparotomy in eight patients with nonresectable multiple HCCs. All patients were treated with a combination of resection or intrahepato-arterial chemotherapy and MTC. A total of 222 bouts of MTC were applied to 21 tumors, the largest of which was 65 mm in largest dimension. The monopolar needle electrode was inserted directly into the tumor and the procedure was repeated at approximately 5 mm intervals.

RESULTS

Levels of alpha-fetoprotein in serum were found to have decreased in all patients one month after surgery with MTC. Contrast-enhanced computerized tomography (CT) showed the complete absence of blood flow in all tumors subjected to MTC. Needle biopsy one month after MTC confirmed tumor necrosis in all cases. All patients are alive at the time of this report, with the longest survival period being 24 months. In three of eight patients, new tumors were confirmed by angiographic CT at sites separate from the treated tumors. MTC resulted in fewer adverse effects on liver function and less extensive inflammatory reactions than liver resection.

CONCLUSION

Intraoperative MTC appears to be an effective method for inducing local tumor necrosis, and may be of use in combination with palliative surgery for multiple HCC when radical liver resection is not feasible.

Improved sensitivity of colour Doppler flow imaging of colorectal hepatic metastases using galactose microparticles: a preliminary report

The clinical application of ultrasonographic contrast agents in colour Doppler flow imaging of hepatic tumours is receiving increasing attention. Levovist is a suspension of galactose microparticles that provides reproducible concentrations of stabilized air bubbles with transpulmonary stability. Its effect on colour Doppler imaging was assessed in 26 patients with colorectal cancer and histologically proven hepatic metastases. Colour Doppler flow imaging was performed before and after intravenous injection of 10 ml Levovist 300 mg/ml. At 5-10 s after injection there was significant enhancement of the hepatic lesions with colour Doppler signals in 23 patients, lasting for a mean(s.d.) of 180(45) s. A consistent pattern of colour Doppler signal was observed, with increased enhancement predominantly around the tumour periphery and little or no central enhancement. These data suggest that Levovist may increase the sensitivity and specificity of colour Doppler flow imaging of colorectal hepatic metastases.

Ultrasound contrast agents: a review

During the past 25 years, many attempts have been made to establish effective ultrasound contrast agents for both cardiac and noncardiac applications. The ideal ultrasound contrast agent would be: (a) nontoxic; (b) injectable intravenously; (c) capable of passing through the pulmonary, cardiac and capillary circulations; and (d) stable for recirculation. A variety of potential ultrasound contrast agents have been or are now under development. Present and future ultrasound contrast agents should provide for increased diagnostic capabilities in a variety of normal and abnormal vessels and organs throughout the body. These agents will enhance tumor vascularity, delineate areas of ischemia, as well as improve visualization of vascular stenosis. Future developments with modification of ultrasound equipment should increase the capabilities of these agents to improve imaging as well as Doppler sensitivity.