An ex-vivo experimental study on optimization of bipolar radiofrequency liver ablation using perfusion-cooled electrodes

PURPOSE

To determine optimal parameters for bipolar radiofrequency ablation (RFA) using perfusion-cooled electrodes to create a large ablation volume in ex vivo bovine liver.

MATERIAL AND METHODS

Three sets of RF experiments were performed using a 200-Watt generator and two 15-gauge perfusion-cooled or internally cooled electrodes in ex vivo bovine livers. In the first set of experiments, to find the ideal inter-electrode distance for creating large coagulation necrosis, 30 ablation lesions were created by bipolar RFAs at inter-electrode spacings of 3 cm, 4 cm, and 5 cm. In the second set of experiments, to explore the ideal duration of RF application, bipolar RFAs were performed for 10 min and 20 min. In the first and second experiments, 10 lesions were made for each condition with infusion of 6% hypertonic saline (HS) at 2 ml/min. In the third set of experiments, 10 ablation lesions were created by bipolar RFAs using internally cooled electrodes without HS infusion. The mean volume of those ablation lesions was then compared to that of the lesions created by bipolar RFA using perfusion-cooled electrodes in the second experiments. Tissue impedance, dimension, and shape of the ablated areas were compared in each condition.

RESULTS

In the first set of experiments, bipolar RFA created a homogeneous oval or spherical-shaped ablation area between the electrodes at 3-5 cm spacing, but showed a more spherical-shaped lesion at 3 cm inter-electrode spacing than at 4 cm and 5 cm spacing. In the second set of experiments, RF energy delivered for 20 min created a larger dimension of coagulation necrosis than energy delivered for 10 min: 107.6 +/- 34 cm3 versus 59.5 +/- 27 cm3 (P<0.05). In addition, the mean volume of ablation regions obtained with bipolar RFA using the internally cooled electrode was 47.5+/- 17 cm3, which was significantly less than that with bipolar RFA using perfusion-cooled electrodes (P <0.05).

CONCLUSION

Bipolar RFA using perfusion-cooled electrodes achieves homogeneous areas of coagulation necrosis between two electrodes, preferably at 3 or 4 cm inter-electrode distance for 20 min, and is better in creating large coagulation necrosis than bipolar RFA using internally cooled electrodes.

Small gastrointestinal stromal tumours with focal areas of low attenuation on CT: pathological correlation

AIM

To describe the pathology of focal areas of low attenuation in small gastrointestinal stromal tumours on contrast-enhanced computed tomography (CT), and to investigate the association of these areas as predictors of malignant potential.

MATERIALS AND METHODS

Contrast-enhanced helical CT images were obtained of 39 small (up to 5 cm) gastrointestinal stromal tumours. Focal areas of low attenuation were retrospectively evaluated and correlated with histopathological findings. The relation between the mitotic rate of and the presence of focal areas of low attenuation in the tumours was analyzed using Fisher's exact test.

RESULTS

Of the 39 small gastrointestinal stromal tumours, 15 contained focal areas of low attenuation on CT. These were found to be due to solid tumour (n=5), haemorrhage (n=3), haemorrhage with necrosis (n=2), cystic degeneration (n=2), fluid in ulcer (n=2), and fibrous septum (n=1); they were not found to be associated with a high mitotic rate (p=0.45).

CONCLUSION

Focal areas of low attenuation on CT in small gastrointestinal stromal tumours represent varying pathological conditions and do not predict malignant potential.

Calcified Klatskin tumor mimicking intrahepatic stone: case report

Calcification is a relatively uncommon manifestation of malignant liver neoplasm. Calcifications in peripheral cholangiocarcinomas but not in Klatskin tumor have been reported. We present a rare case of Klatskin tumor that had dystrophic calcification mimicking a intrahepatic stone in a 65-year-old man.

Hepatic bipolar radiofrequency ablation using perfused-cooled electrodes: a comparative study in theex vivobovine liver

The purpose of this paper was to demonstrate the efficacy of the dual probe bipolar radiofrequency (RF) system with the perfused-cooled electrodes inducing coagulation necrosis in the ex vivo bovine liver. The perfused-cooled electrode that allows simultaneous internal cooling and interstitial hypertonic saline perfusion has been developed for RF ablation (RFA). RF was applied to excised bovine liver in a bipolar mode at 150 W using a 200 W generator with two perfused-cooled electrodes for 10 min. After placing the electrodes at 3 cm spacing in the explanted liver, 45 ablation zones were created with three different regimens: Group A, using both intraelectrode cooling and interstitial perfusion; group B, using only the intraelectrode cooling; and group C, using only interstitial perfusion. In groups A and C, RFA was performed with the infusion of 6% hypertonic saline at the rate of 2 ml min(-1). During RFA, we measured the tissue temperature at the midpoint between the two electrodes. The dimensions of the ablation zones and the changes in impedance, currents and liver temperature during RFA were compared in these three groups. The mean tissue impedance during RFA in group A (56.7+/-21.7 Omega) and group C (56.9+/-20.6 Omega) was significantly lower than group B (112+/-19.7 Omega) (p<0.001). The mean current was higher in group A (1765+/-128 mA) than groups B (760+/-321 mA) and C (1298+/-349 mA) (p<0.05). In addition, the shortest vertical diameter of coagulation necrosis was greater in groups A (4.9+/-0.5 cm) and C (4.6+/-0.7 cm) than in group B (3.5+/-0.4 cm) (p<0.05). The temperature at the mid-point between the two probes was higher in group A than other groups: 99 degrees C in group A, 88.9 degrees C in group B, and 94.3 degrees C in group C (p>0.05). The ratios of the diameter of the long-axis to the diameter of the vertical-axis of groups A, B and C were 1.1+/-0.1, 1.2+/-0.1, and 1.1+/-0.2, respectively (p<0.05). Bipolar RFA using intraelectrode cooling and the interstitial saline perfusion simultaneously produced ablation zones significantly larger than the area produced by only one measure.

Cellular niches controlling B lymphocyte behavior within bone marrow during development

In bone marrow, hematopoiesis is thought to depend on special microenvironments known as niches that maintain blood cells. However, the identity of niches and interaction of blood cells with niches remain poorly understood. Here we identify stage-specific cellular niches for B lymphopoiesis. The earliest precursors, pre-pro-B cells and end-stage B cells, plasma cells require CXC chemokine ligand (CXCL)12. CXCL12-expressing cells are a small population of stromal cells, scattered throughout bone marrow and located some distance from the cells expressing interleukin (IL)-7. Multipotent hematopoietic progenitors are attached to the processes of CXCL12-expressing cells and pre-pro-B cells adjoin their cell bodies. Maturer pro-B cells that require IL-7 have moved away and adjoin the IL-7-expressing cells. Plasma cells again seed CXCL12-expressing cells. We demonstrate the B lymphocyte characteristic location and movement between specific niches within bone marrow during development and suggest that CXCL12 maintains the cells in the niche.

Real-time compound ultrasonography: pictorial review of technology and the preliminary experience in clinical application of the abdomen

The purposes of this essay are to illustrate the technology overview and theoretical benefits of real-time compound ultrasonography (US) and to present our preliminary clinical experience in the evaluation of normal and diseased abdomens. The application of compounding principles to real-time US and its recent reintroduction into mainstream commercial systems have offered new opportunities for its clinical application to the routine examination of the abdomen. In our early preliminary experience, this technique effectively suppressed many of the US artifacts, better depicted the margin or boundary of the lesion, and increased contrast resolution or lesion conspicuity. Therefore, we believe that real-time compound US is a promising technique that may enhance the diagnostic confidence of the examination in the evaluation of normal and diseased abdomens.

Afferent loop obstruction after gastric cancer surgery: helical CT findings

BACKGROUND

We reviewed the computed tomographic (CT) findings of afferent loop obstruction and assessed the value of helical CT in determining the underlying cause.

METHODS

Helical CT scans of 18 patients (12 men and six women; age range = 35-67, mean age = 50 years) with afferent loop obstruction were reviewed. All patients had gastric cancer. Ten patients had undergone radical subtotal gastrectomy with Billroth II gastrojejunostomy, and eight had undergone total gastrectomy with Roux-en-Y esophagojejunostomy. CT images were analyzed retrospectively, and the presumed cause of obstruction on CT was compared with surgical findings (n = 8) and clinical courses (n = 10).

RESULTS

Local recurrence (n = 15), peritoneal seeding (n = 1), internal hernia (n = 1), and adhesion (n = 1) were the presumed causes of obstruction on CT. In all eight patients who underwent a second operation, the cause of afferent loop obstruction was correctly suggested on CT (local recurrence in six patients and adhesion and internal hernia in one patient). In 10 patients who were not re-explored, the clinical findings or biopsy indicated recurrent tumor as suggested on CT.

CONCLUSION

Recurrent tumors and other potential causes of afferent loop obstruction can be correctly predicted with CT in most cases.

Helical CT of postoperative patients with gastric carcinoma: value in evaluating surgical complications and tumor recurrence

BACKGROUND

We assessed computed tomographic (CT) features of postoperative complications and recurrent tumors in gastric cancer patients who underwent radical surgery.

METHODS

We performed a retrospective study of 397 patients who had undergone radical surgery for the treatment of gastric carcinoma and underwent postoperative CT in our institution over a 2-year period. Patients were assigned to one of two groups: group A consisted of 47 patients who underwent CT for complications in the early postoperative period, and group B consisted of 355 patients who underwent CT for evidence of tumor recurrence during the follow-up period. We classified recurrent tumors into four categories: local recurrence, lymph node metastasis, peritoneal seeding, and remote metastasis.

RESULTS

In group A, localized fluid collections or abscesses in the surgical bed were found in 38 patients (81%) and usually involved the left subphrenic area (74%) or the superior recess of the lesser sac (47%). In group B, recurrent tumors were found in 196 patients (55%). Among these, lymph node metastasis was the most common pattern (52%), followed by peritoneal seeding (44%), local recurrence (40%), and remote metastasis (37%).

CONCLUSION

CT after radical surgery for the treatment of gastric carcinoma frequently shows postoperative complications or tumor recurrence. Familiarity with the common postoperative complications and patterns of the tumor recurrence is a prerequisite to accurate interpretation of CT findings in these patients.

Contrast-enhanced dynamic ultrasonography of the liver: optimization of hepatic arterial phase in normal volunteers

BACKGROUND

To optimize hepatic arterial phase timing in contrast-enhanced dynamic ultrasonography (US) of the liver.

METHODS

Dynamic US was performed by using a microbubble-specific mode in 22 healthy volunteers after bolus injection of SH U 508A. Images were analyzed to determine whether hepatic arterial and portal venous phases could be temporally discriminated. Delay times to contrast enhancement at the hepatic artery (A(ini)) and portal vein (P(ini)) and the delay time until the signals between both vessels became inseparable (A(end)) were determined.

RESULTS

The hepatic arterial and portal venous phases could be temporally discriminated in all subjects. A(ini), P(ini), and A(end) (mean +/- standard deviation) were 11.0 +/- 2.0, 14.8 +/- 3.6, and 22.6 +/- 5.1 s, respectively.

CONCLUSION

In hepatic contrast-enhanced dynamic US, hepatic arterial phase scanning should be commenced earlier than 11 s and terminated after 23 s postinjection.

Abdominal amyloidosis: spectrum of radiological findings

Amyloidosis is a disease characterized by the deposition of fibrillar protein amyloid of beta-structure in organs or tissues. It is usually classified as either a primary disease or secondary to a co-existent condition, such as rheumatoid arthritis, tuberculosis, or neoplasm (particularly multiple myeloma or renal cell carcinoma). Amyloid protein deposition can be seen in a variety of organs though it occurs with higher frequency in the gastrointestinal tract, kidney, and heart. Amyloidosis can have a wide spectrum of manifestations in nearly every abdominal organ. Some of these, for example, multiple cystic submucosal masses of the stomach, amyloidosis of the gallbladder, and dirty soft tissue infiltration of the subcutaneous fat, have not yet been covered in the radiological literature. The combination of various imaging techniques and the identification of characteristic computed tomography (CT) hepatic features may help in the differentiation of amyloidosis from other infiltrative diseases; however, confirmative diagnosis can usually only be achieved by tissue biopsy.

Focal eosinophilic infiltration in the liver: radiologic findings and clinical course

BACKGROUND

We investigated the radiologic findings and clinical course of focal eosinophilic infiltration in the liver.

METHODS

We retrospectively reviewed computed tomographic (CT) and sonographic scans in 20 patients (18 male, two female; mean age, 50 years) with pathologically or clinically proven focal eosinophilic infiltration in the liver by two experienced radiologists in our institute from August 1995 to June 1999. We also correlated radiologic findings with peripheral eosinophil count. Radiologic and clinical findings during the follow-up (range, 2-49 months; mean, 19.5 months) also were analyzed.

RESULTS

Clinical symptoms and signs included abdominal pain (n = 4), easy fatigability (n = 3), weight loss (n = 1), and peripheral eosinophilia (n = 19). Twelve patients were asymptomatic. On sonographic examinations, all lesions were seen as focal, low echoic nodules. On CT, the lesions appeared isoattenuated or low attenuated in the arterial phase and low attenuated in the portal phase, except one case that showed high attenuation in the arterial phase. The margins of most lesions appeared poorly defined. Lesions were single (n = 9) and multiple: two to five (n = 6), six to 10 (n = 3), and more than 10 (n = 2). Each lesion was smaller than 2 cm; only one was 4 cm in diameter. The distribution of the lesion was subcapsular in 14 patients and central in five. Diffuse dissemination was observed in one. Eosinophil-associated abnormality was not present in other abdominal organ in all cases. The peripheral eosinophil count correlated closely with the number but not with the size of lesions. Sixteen patients who had follow-up images showed complete (n = 14) or partial regression of the lesions with a decrease in size (n = 1) or number (n = 1) after 2-22 months (mean, 6.4 months).

CONCLUSION

Focal eosinophilic infiltration in the liver had somewhat characteristic radiologic findings on sonography and CT. In the correct clinical context of peripheral eosinophilia and self-limited course, these radiologic findings may be helpful in differentiating this condition from other focal hepatic lesions.

Biliary obstruction in metastatic disease: thin-section helical CT findings

BACKGROUND

We describe the thin-section helical computed tomographic (CT) findings of biliary obstruction caused by metastasis.

METHODS

Thin-section helical CT (5 mm slice thickness, 1:1 pitch, portal phase) and direct cholangiography in 50 consecutive patients with biliary obstruction caused by metastases were reviewed retrospectively by three radiologists. The primary sites were the stomach ( n = 36), colon ( n = 12), jejunum ( n = 1), and uterus ( n = 1). The level of biliary obstruction was analyzed with the Bismuth classification, and the CT findings of biliary obstruction were classified into six types: small (<2 cm) periductal masses, large (>/=2 cm) periductal masses, extrinsic compression by a metastatic liver mass, high-attenuation intraductal mass, intrapancreatic mass, and no demonstrable lesion.

RESULTS

The level of biliary obstruction was the hilum in 18 patients (36%), the proximal common duct in 20 (40%), the distal common duct in five (10%), and the periampullary area in seven (14%). Of 18 hilar obstructions, tumor involvement of the secondary confluence of intrahepatic bile ducts was seen in 10 (right in six, left in one, and bilateral in three). Periductal masses were seen in 68% (small in 18, large in 16). In one patient (2%), a large metastatic mass of the liver resulted in extrinsic compression and biliary obstruction. Lesions mimicking primary biliary or pancreatic tumor were seen in four, respectively. In seven, we found no obstructing lesion on CT.

CONCLUSION

Biliary obstruction in patients with known primary malignancies can show atypical patterns mimicking primary pancreatobiliary malignancies on thin-section helical CT.

Acute hepatic vein occlusion: spiral CT findings in an experimental study

BACKGROUND

We investigated spiral computed tomographic (CT) findings and underlying hemodynamic alterations in acute hepatic vein occlusion.

METHODS

In nine dogs, immediately after balloon occlusion of the right ( n = 4) or left ( n = 5) hepatic vein through the transjugular or transfemoral route, we performed single-level dynamic CT with intravenous administration of contrast medium. We created time attenuation curves of individual hepatic segments showing attenuation differences. To investigate underlying hemodynamic alterations, hepatic arteriograms were obtained in two dogs.

RESULTS

In all cases, there were three compartments with different time attenuation curves: normal, occluded, and adjacent. The normal compartment, which comprised segments far from the occluded hepatic compartment, showed the normal pattern of hepatic enhancement. The occluded compartment, which was the drainage territory of the occluded hepatic vein, showed high attenuation in the early arterial phase and low attenuation in the portal phase. The adjacent compartment, which shared the same portal vein with the occluded compartment and was drained by the patent hepatic vein adjacent to the occluded one, showed strong contrast enhancement in the late arterial and early portal phase. Spiral CT and hepatic arteriography demonstrated the arterioportal shunt and reversed portal venous flow in the occluded compartment, which drained into the adjacent compartment.

CONCLUSION

Acute hepatic vein occlusion on spiral CT appears as mild, early arterial, high attenuation and portal low attenuation of the occluded compartment and strong enhancement in the late arterial and early portal phases of the adjacent compartment due to arterioportal shunt and reversed portal flow.

Gastric mucosa-associated lymphoid tissue lymphoma: spectrum of findings at double-contrast gastrointestinal examination with pathologic correlation

Mucosa-associated lymphoid tissue (MALT) is found in the surface epithelium of the stomach. MALT lymphoma is extranodal lymphoma originating from MALT. In the stomach, a strong association with Helicobacter pylori infection has been demonstrated. Low-grade gastric MALT lymphoma has been reported to have variable features at upper gastrointestinal (UGI) examination. Twenty-two patients with low-grade MALT lymphoma had ulcers (n = 11), fold thickening (n = 7), mucosal nodularity (n = 7), masses (n = 6), or prominent areae gastricae (n = 4) at UGI examination. Six patients with high-grade MALT lymphoma had masses (n = 4), fold thickening (n = 3), ulcers (n = 1), or mucosal nodularity (n = 1) at UGI examination. These findings were similar to those in gastric carcinoma or gastritis. Differentiation of low-grade MALT lymphoma from gastritis or gastric carcinoma was more difficult than differentiation of high-grade MALT lymphoma. Lesions of MALT lymphoma associated with H pylori gastritis were diffuse or multiple in 65% of cases; however, lesions of MALT lymphoma without proved H pylori gastritis were focal or solitary in 80% of cases. Therefore, multiplicity of lesions in MALT lymphoma was closely associated with H pylori infection.

Comparison of contrast-enhanced fundamental imaging, second-harmonic imaging, and pulse-inversion harmonic imaging

RATIONALE AND OBJECTIVES

To investigate the feasibility of recent contrast-specific ultrasound techniques in depicting vascular flow and the effects of changing the output power of the transducer and insonation mode on contrast enhancement, the authors performed an experimental study with a flow phantom.

METHODS

While changing the mechanical index and the sound insonation mode (continuous and intermittent), images were obtained with three contrast-enhanced ultrasound techniques: fundamental, second-harmonic, and pulse-inversion harmonic imaging (PIHI) after a bolus injection of microbubble contrast agent. The images were compared on a time-intensity curve.

RESULTS

In assessing fixed flow (10 cm/s), PIHI showed the best depiction of flow signal. In intermittent scanning, increases in the mechanical index caused stronger flow signals and longer enhancement duration in all techniques. However, continuous scanning revealed poor depiction of flow signal regardless of the technique or changes in the mechanical index because of significant bubble destruction.

CONCLUSIONS

Microbubble-enhanced PIHI with intermittent scanning at a high mechanical index can depict vascular flow highly effectively without shortening the duration of enhancement.

Hepatic hemangiomas with arterioportal shunt: findings at two-phase CT

PURPOSE

To determine the prevalence of arterioportal shunt associated with hepatic hemangiomas, describe the two-phase spiral computed tomographic (CT) findings, and correlate the presence of arterioportal shunt with the size and rapidity of enhancement of hemangiomas.

MATERIALS AND METHODS

The study group consisted of 109 hepatic hemangiomas in 69 patients who underwent two-phase spiral CT during 1 year. CT scans were obtained during the hepatic arterial (30-second delay) and portal venous (65-second delay) phases after injection of 120 mL of contrast material (3 mL/sec). Arterioportal shunts were diagnosed when hepatic arterial phase CT scans showed a wedge-shaped or irregularly shaped homogeneous enhancement in the liver parenchyma adjacent to the tumor and when portal venous phase CT scans showed isoattenuation or slight hyperattenuation, compared with normal liver in that area, and when there was no demonstrable cause of these attenuation differences. The presence of arterioportal shunt in hemangioma was correlated with the size of the tumor and the rapidity of intratumoral enhancement.

RESULTS

Arterioportal shunt was found in 28 (25.7%) of 109 hemangiomas. There was no statistically significant relationship between lesion size and presence of the arterioportal shunt (P =.653). Arterioportal shunt was more frequently found in hemangiomas with rapid enhancement (P <.01).

CONCLUSION

Arterioportal shunts are not uncommonly seen in hepatic hemangiomas at two-phase spiral CT. Hemangiomas with arterioportal shunts tend to show rapid enhancement.

Viable myocardium in reperfused acute myocardial infarction: rest and stress first-pass mr imaging

Feasibility of identifying viable myocardium in rest and stress magnetic resonance imaging (MRI) was evaluated using 3 hr occlusion and 30 min reperfusion model of left anterior descending (LAD) coronary artery in 12 felines. At rest MRI, viable myocardium confirmed by 2,3,5-triphenyl tetrazolium chloride (TTC)-staining showed rapid signal intensity (SI) rise followed by gradual decline not significantly different from normal myocardium that the two hyperperfused regions were distinguishable only from the hypoperfused nonviable myocardium. At stress MRI, hyperemia induced perfusion change was most pronounced in normal myocardium with earlier and greater peak enhancement followed by brisk 'washout' phase while minimally augmented enhancement in viable myocardium was still in 'washin' phase. From these findings, it was concluded that viable myocardium is identified in rest and stress MRI as redistributing hypo- perfusion compared to persistent hyper-perfusion of the normal myocardium and the persistent hypo-perfusion of the nonviable myocardium.

Three-dimensional spiral CT cholangiography with minimum intensity projection in patients with suspected obstructive biliary disease: comparison with percutaneous transhepatic cholangiography

BACKGROUND

To evaluate the diagnostic potential of spiral computed tomographic (CT) cholangiography with minimum intensity projection (minIP) in the diagnosis of patients with suspected biliary obstruction.

METHODS

Nine consecutive patients with obstructive biliary disease were enrolled in this study. Spiral CT data (3-mm slice thickness, pitch 1-2:1) obtained 65 s after the start of contrast medium injection (150 mL Ultravist 370, 3 mL/s) were reconstructed at 1-mm intervals. Three-dimensional (3D) CT cholangiography with minIP (3D CTC) was generated with a Siemens software package. The quality of 3D CTC in its ability to demonstrate the anatomic detail, the level of obstruction, and the presence or absence of isolated hepatic segments was evaluated using percutaneous transhepatic cholangiography as a gold standard.

RESULTS

In all patients, 3D CTC demonstrated dilated intrahepatic ducts up to tertiary branches. 3D CTC correctly diagnosed the level of biliary obstruction and demonstrated isolated segments in all patients. In determining the cause of biliary obstruction, one patient with hilar cholangiocarcinoma was misdiagnosed as having biliary invasion by hepatocellular carcinoma.

CONCLUSION

3D CTC with minIP can determine the level and cause of biliary obstruction. 3D CTC can be obtained from regular thin-section helical CT data and may be a strong competitor against diagnostic magnetic resonance cholangiography because of its superior resolution and information on adjacent soft tissues and the duct itself.

Peripheral T-cell lymphoma of the colon: double-contrast barium enema examination findings in six patients

PURPOSE

To evaluate radiologic findings of peripheral T-cell lymphoma (PTCL) of the colon at double-contrast barium enema examination.

MATERIALS AND METHODS

Double-contrast barium enema findings in six patients with pathologically proved PTCL of the colon were retrospectively evaluated and compared with colonoscopic and histopathologic findings.

RESULTS

There was a diffuse involvement of almost all segments of the colon in four patients and a focal segmental involvement in two. Frequent findings at double-contrast barium enema examination included geographic ulcerations (n = 6), aphthous ulcerations (n = 4), pseudopolyps (n = 4), circumferential luminal narrowing (n = 4), and ileocecal deformity (n = 4).

CONCLUSION

PTCL of the colon manifested as either a diffuse or a focal segmental lesion and showed extensive mucosal ulceration at double-contrast barium enema examination. These findings are similar to those of inflammatory bowel disease and are different from those of colorectal lymphoma with the B-cell phenotype.

Quantitative comparison of tumor vascularity of hepatocellular carcinoma after intravenous contrast agent: conventional versus harmonic power Doppler US

BACKGROUND

The purpose of this study was to make a quantitative comparison between conventional and harmonic power Doppler (PD) ultrasound (US) in depicting vascularity of hepatocellular carcinoma (HCC).

METHODS

Ten nodular HCCs in 10 patients were prospectively examined using a 2-4-MHz convex transducer and a standardized examination protocol. Serial US images were obtained before and 20, 30, 40, 50, 60, 90, 120, 150, 180, 240, and 300 s after intravenous injection of 2 g of contrast agent using conventional and harmonic PD US. The percentage of area with Doppler signal within each HCC nodule (%PDA) was calculated in each image with a PC-based image analysis program, and the results with both US techniques were compared.

RESULTS

In the majority of cases, %PDA was greater on conventional PD US than on harmonic PD US. Mean %PDA of 10 HCCs was significantly higher on conventional PD US than on harmonic PD US except at 20 s after injection. The highest values of mean %PDA were 34.9% in conventional PD US and 19.5% in harmonic PD US at 60 s after injection.

CONCLUSION

Area with PD signals within the HCC is smaller and the duration of effective enhancement is shorter in harmonic PD US than in conventional PD US.