Conventional Gray-scale Ultrasonography Research Articles

Is Ultrasound a Viable Imaging Modality for the Diagnosis of Hepatocellular Carcinoma? A Cross-Sectional Study

Background: Radiologists are always questioning the use of an imagine modality as compared to the other, this study helps answer that question for the diagnosis of Hepatocellular carcinoma. Objective: To compare the use of MRI imaging technique with ultrasonography for the diagnosis of hepatocellular carcinoma. Study Design: The type of study is a Prospective Cross-Sectional study. Settings: A large tertiary care hospital in Karachi, Pakistan. Duration: One year from July 2018 to July 2019. Methodology: The inclusion criteria was all the patients who were referred to us with symptoms for concern for hepatic tumors. For the MRI we used a 1.5 tesla machine, and for the ultrasound we used a conventional grey scale ultrasonography with a probe of 5 MHz. We performed multiphasic contrast enhanced MRI’s, with images taken both before the injection of the contrast and afterwards in the various phases such as the arterial phase, portal venous phase and finally the delayed phase respectively. Results: The study population consisted of n=110 patients having a mean age of 46.5 +/- 5.50 years. There were n= 78 (70.90%) males and n= 32 (20.09%) females. N= 101 (91.81%) patients had a diagnosis of hepatocellular carcinoma as per MRI scan, for ultrasound n= 47 (42.72%) patients were diagnosed as true positive, n= 2 (1.81%) were false positive, n= 54 (49.09%) were false negative, while n= 7 (6.36%) cases were truly negative. The specificity was 77.77% the sensitivity was 46.53%, the positive predictive value was 95.91%, negative predictive value was 11.4%, and accuracy was 49.09% respectively. Conclusion: We found that the specificity of ultrasound as a diagnostic modality for hepatocellular carcinoma as compared to the MRI scan is good, however it is only able to correctly identify about half the patients, hence care should be taken when interpreting the results of ultrasound for hepatocellular carcinoma.

Differentiation of adrenal hemorrhage from adrenal malignancies in a neonatal case by superb microvascular imaging

Neonatal adrenal hemorrhages (NAH) may be encountered in cases of perinatal asphyxia. The differentiation of malignant lesions and bleeding in the adrenal gland detected in the neonatal period is very important for treatment and prognosis. Ultrasonography (US) is the first preferred imaging method in NAH because it is non-invasive and easy to apply. Vascularization is not detected in hematomas in Doppler US examination. However, conventional Doppler imaging techniques (CDIT) may not adequately show the blood flow (BF) of the lesions. Super micro-vascular imaging (SMI) is a new vascularization imaging technique that eliminates motion artifacts, provides detailed information about very slow blood flow, and allows imaging of microvascular structures. SMI can be operated in 2 modes: color SMI (cSMI) and monochrome SMI (mSMI). The cSMI mode simultaneously displays a conventional grayscale US with color-coded Doppler signals. The monochrome SMI mode improves the visibility of vascular structures by eliminating background signals and focusing only on vasculature signals. In this case report, we aimed to present a case of NAH detected by SMI in the neonatal period and we wanted to emphasize the usefulness of SMI.

Comparative Efficacy of Ultrasonography and Acoustic Radiation Force Impulse (ARFI) Elastography in Prediction of Malignancy in Thyroid Nodules

Objective: The incidence of malignancy in thyroid nodules is infrequent, but this trend may be reversing. The present study was conducted to emphasize the diagnostic accuracy of acoustic radiation force impulse (ARFI) imaging, in addition to conventional gray-scale ultrasonography (US), for differentiating benign and malignant thyroid nodules. Methods: A total of 141 patients with thyroid nodules (≥10 mm) were included in the study and were evaluated with US, Doppler, and ARFI elastography using Siemens S2000 Acuson ultrasound equipment. Results: The sonographic patterns most predictive and indicative of malignancy included irregular margins and presence of microcalcifications. The Doppler findings in isolation were not extremely sensitive in the detection of malignancy. The shear wave velocity cutoff value on ARFI imaging using receiver operating characteristic curves for differentiation of benign and malignant nodules were noted at 2.87 m/s. ARFI imaging performed better than US and Doppler with sensitivity of 75%, specificity of 96%, and accuracy of 94%. Conclusion: ARFI elastography could be utilized as a reliable initial screening test for detection of malignancy in thyroid nodules.

Role of Combining Colour Doppler and Grey Scale Ultrasound in Differentiating Benign from Malignant Ovarian Masses

Abstract The aim of this study was to evaluate ovarian masses with conventional grey scale ultrasonography and colour Doppler flow imaging and to assess the diagnostic reliability of these methods in differentiating benign and malignant ovarian masses. We assessed 56 patients with an ovarian mass. Morphological characterisation of the mass was performed utilising the Sassone score. Colour Doppler parameters were recorded for each patient, and the Caruso vascular score was also applied. The results were compared with surgical/pathological and/or follow-up scans. Using the Sassone score, overall reliability in differentiating ovarian masses had a sensitivity of 89.5% and a specificity of 78.4%. Using the Caruso score alone, we found a sensitivity of 89.5% and a specificity of 86.5%. Using the Sassone and Caruso scores together, we found a sensitivity of 94.7% and a specificity of 89.1%. Combining both morphological and colour Doppler scores in the evaluation of ovarian masses obtained higher specificity, sensitivity, and accuracy than was obtained using a single score only.

Significance of contrast-enhanced ultrasonography in differential diagnosis of thyroid nodules.

The present study was aimed to compare the application values between 2-dimensional color Doppler ultrasonography (2DUS) and contrast-enhanced ultrasonography (CEUS) in the differential diagnosis of thyroid malignant nodules.A total of 124 patients suspectedly diagnosed with malignant thyroid nodules under conventional gray-scale ultrasonography were recruited in this study. All enrolled patients were examined by both 2DUS and CEUS.A total of 153 nodules (94.44%) and 45 cases (90.00%) with malignant nodules were detected by the CEUS. No significant differences were noted in nodule detection rates between 2DUS and CEUS (χ2 = 1.170, P = .279; χ2 = 0.796, P = .372). The aspect ratio, microcalcification, internal echo, borderline, Vmax, resistance index, and total scores of malignant nodules were higher than those of benign nodules (all P < .05) when diagnosed by 2DUS. The peripheral/internal enhancement time, peak intensity, local enhancement, ring enhancement, and total scores of malignant nodules were significantly higher compared with those of benign nodules (all P < .05) by CEUS. Total score of malignant nodules diagnosed by 2DUS was approximately 3.5 and 2.3 points for CEUS. The diagnostic accuracy of 2DUS as observed by area under the curve was 0.821 with the cut-off value of 3.9, the sensitivity was 82.5%, and the specificity was 85.6%. The diagnostic accuracy of CEUS was 0.862 with the cut-off value of 2.8, the sensitivity was 86.7%, and the specificity was 91.3%.Both 2DUS and CEUS are worthy of application values in the differential diagnosis from benign to malignant thyroid nodules.

Additional value of qualitative strain ultrasound elastography and strain ratio in predicting thyroid malignancy

ObjectiveTo detect if strain ultrasound elastography and strain ratio have additional value to the conventional grey scale ultrasound in predicting thyroid malignancy. Patients and methodsThis study included 92 thyroid nodules from 62 patients (the mean age was 40.64 ± 13.93). Morphologic aspects of the thyroid nodule in conventional grey scale ultrasonography and elastographic examinations with elastography score and strain ratio (SR) were performed for all nodules. The final diagnosis was confirmed by fine needle aspiration biopsies in 72 nodules and by excisional biopsies in 20 nodules. ResultsWe found that combination of both conventional ultrasound and strain elastography score have the best diagnostic performance with sensitivity, specificity, PPV, NPV and accuracy accounting for 80%, 97%, 57%, 99% and 96% respectively. The means SR for benign nodules (1.37 ± 0.56) was significantly lower than that for malignant nodules (3.0 ± 0.71) [p-value .003].The optimal SR cutoff is 2.5 with estimated 80% sensitivity, 98% specificity, PPV 67%, NPV 99% and accuracy 97%. ConclusionThe clinical application of elastography score and SR should be carried out hand in hand with conventional sonographic assessment of thyroid nodules to achieve the best diagnostic performance.

Elastography: Applications in Peripheral Nerves

The biomechanical properties of soft tissues reflect to some degree the pathophysiology of musculoskeletal disorders. Conventional gray-scale sonography has been widely used as a first-line approach for musculoskeletal disorders because of the advantage of real-time access. Sonoelastography, which we refer to here as strain elastography (SE), requires manual compression vibration and is a modality for quantitatively measuring the elasticity of soft tissue through conventional gray-scale sonography with estimated Young’s modulus or semi-quantitative values as strain ratios. By using the semi-quantitative values of strain ratios, SE has demonstrated promising preliminary results for the diagnosis of masses of the liver, breast, pancreas, prostate, and thyroid, with defined cutoff values. In peripheral nerve disorders, SE could be preferable in clinical practice for detecting the biomechanical changes of tendons, muscles, and ligaments surrounding the nerve, to diagnose and plan preoperational or interventional management. Recently, by using SE, several studies have provided insight into the biomechanical properties and pathophysiological changes associated with entrapment neuropathy as typified by carpal tunnel syndrome. In this presentation, the current knowledge of sonoelastographic techniques and their use for peripheral nerve disorders will be reviewed.

Added Value of Contrast-Enhanced Ultrasonography as a Planning Modality for Radiofrequency Ablation of Hepatocellular Carcinoma: Comparison with Gray-Scale Ultrasonography

Background: Radiofrequency ablation (RFA) is not feasible when hepatocellular carcinoma (HCC) is poorly defined or invisible on conventional gray-scale ultrasonography (GSUS). Recent introduction of contrast-enhanced ultrasonography (CEUS) helps diagnose HCC by showing its typical enhancement pattern. Objectives: The purpose of this study is to demonstrate the added value of CEUS as a RFA planning modality for HCC compared with conventional GSUS. Patients and Methods: A total of 64 HCCs from 57 patients (men:women = 41:16; mean age, 62.6) who had undergone GSUS and CEUS for RFA planning in 2011 were retrospectively reviewed. Ultrasound contrast agent was used for CEUS after conventional GSUS. The recorded images of GSUS and CEUS were reviewed retrospectively. On GSUS, the size, location, echogenicity, and margin of each HCC were reviewed. The visibility scores of HCC on GSUS and CEUS were measured using a 3-point scale. GSUS visibility score: score 1, definite nodule with well-defined margin; score 2, slightly hypo-/hyperechoic nodule with partial margin; score 3, isoechoic nodule without margin. CEUS visibility score: score 1, arterial enhancement; score 2, only delay washout; score 3, no arterial enhancement or washout. Results: The mean size of HCCs was 1.8 cm (range, 1.0 - 4.8 cm). Among 64 HCCs, visibility score 1 were 37; score 2, 8; score 3, 19 on GSUS. By performing CEUS, 10 out of 19 HCCs with GSUS visibility score 3 showed CEUS visibility score 1. Seven out of 8 HCCs with GSUS visibility score 2 showed CEUS visibility score 1. Total 37 HCCs showed visibility score 1 on GSUS; whereas, 53 HCCs showed visibility score 1 on CEUS (57.8% vs. 82.8%). Conclusions: CEUS can be an effective RFA planning modality when a target HCC is invisible or questionable on GSUS.

Differential diagnosis of idiopathic granulomatous mastitis and breast cancer using acoustic radiation force impulse imaging.

Differentiation of idiopathic granulomatous mastitis (IGM) from carcinoma with routine imaging methods, such as ultrasonography (US) and mammography, is difficult. Therefore, we evaluated the value of a newly developed noninvasive technique called acoustic radiation force impulse imaging in differentiating IGM versus malignant lesions in the breast. Four hundred and eighty-six patients, who were referred to us with a presumptive diagnosis of a mass, underwent Virtual Touch tissue imaging (VTI; Siemens) and Virtual Touch tissue quantification (VTQ; Siemens) after conventional gray-scale US. US-guided percutaneous needle biopsy was then performed on 276 lesions with clinically and radiologically suspicious features. Malignant lesions (n=122) and IGM (n=48) were included in the final study group. There was a statistically significant difference in shear wave velocity marginal and internal values between the IGM and malignant lesions. The median marginal velocity for IGM and malignant lesions was 3.19m/s (minimum-maximum 2.49-5.82) and 5.05m/s (minimum-maximum 2.09-8.46), respectively (p<0.001). The median internal velocity for IGM and malignant lesions was 2.76m/s (minimum-maximum 1.14-4.12) and 4.79m/s (minimum-maximum 2.12-8.02), respectively (p<0.001). The combination of VTI and VTQ as a complement to conventional US provides viscoelastic properties of tissues, and thus has the potential to increase the specificity of US.

Quantitative measurement of elasticity of the appendix using shear wave elastography in patients with suspected acute appendicitis.

IntroductionShear wave elastography (SWE) has not been studied for diagnosing appendicitis. We postulated that an inflamed appendix would become stiffer than a normal appendix. We evaluated the elastic modulus values (EMV) by SWE in healthy volunteers, patients without appendicitis, and patients with appendicitis. We also evaluated diagnostic ability of SWE for differentiating an inflamed from a normal appendix in patients with suspected appendicitis.Materials and MethodsForty-one patients with clinically suspected acute appendicitis and 11 healthy volunteers were prospectively enrolled. Gray-scale ultrasonography (US), SWE and multi-slice computed tomography (CT) were performed. The EMV was measured in the anterior, medial, and posterior appendiceal wall using SWE, and the highest value (kPa) was recorded.ResultsPatients were classified into appendicitis (n = 30) and no appendicitis groups (n = 11). One case of a negative appendectomy was detected. The median EMV was significantly higher in the appendicitis group (25.0 kPa) compared to that in the no appendicitis group (10.4 kPa) or in the healthy controls (8.3 kPa) (p<0.001). Among SWE and other US and CT features, CT was superior to any conventional gray-scale US feature or SWE. Either the CT diameter criterion or combined three CT features predicted true positive in 30 and true negative in 11 cases and yielded 100% sensitivity and 100% specificity. An EMV of 12.5 kPa for the stiffest region of the appendix predicted true positive in 28, true negative in 11, and false negative in two cases. The EMV (≥12.5 kPa) yielded 93% sensitivity and 100% specificity.ConclusionOur results suggest that EMV by SWE helps distinguish an inflamed from a normal appendix. Given that SWE has high specificity, quantitative measurement of the elasticity of the appendix may provide complementary information, in addition to morphologic features on gray-scale US, in the diagnosis of appendicitis.

Ultrasound-guided percutaneous laser and ethanol ablation of rabbit VX2 liver tumors

Only a small percentage of patients with hepatocellular carcinoma (HCC) may benefit out of surgical resection. Thus, lots of these patients are in need of local control, such as percutaneous ethanol injection (PEI), percutaneous laser ablation (PLA), or radiofrequency thermal ablation (RF). To investigate the effects of ultrasound-guided PLA combined with PEI on rabbit VX2 liver tumors, using conventional gray-scale ultrasonography (US), color/power Doppler (CD/PD)US, contrast-enhanced (CE) US, and histologic examination. VX2 tumors were implanted in the livers of 80 rabbits. Fourteen days after implantation, animals were randomly separated into four groups of 20 rabbits. Treatment of the four groups was with: (i) PLA; (ii) PEI; (iii) combined therapy of PLA immediately followed by PEI; and (iv) combined therapy of PEI immediately followed by PLA. Conventional gray-scale US, CD US, PD US, and CE US were performed before and after ablation. The effects on ablated areas were assessed by histologic examination. Conventional gray-scale US showed a clear boundary around the ablated area in groups 1, 3, and 4. An isoechoic treated region with an irregular boundary was seen in group 2. On CE US, coagulated areas demonstrated a perfusion defect. Both conventional gray-scale US and CE US showed that the ablated volume in group 4 was larger than that in groups 1, 2, and 3. CD US and PD US demonstrated residual tumor in the periphery of ablated areas in groups 1 and 2, but not in groups 3 and 4. CE US demonstrated no residual tumor in group 4, unlike in groups 1, 2, and 3. Examination of treated tumors demonstrated necrosis in the ablated zones and increasing surrounding fibrous bands in the four treatment groups. Residual viable tissue in group 4 was less than that in groups 1, 2, and 3. Combined therapy of PEI immediately followed by PLA can coagulate significantly larger volumes of tumor and reduce residual tumor.

Dynamic power Doppler ultrasonography of anterior abdominal wall hernias: confirmation of incarceration.

Power Doppler ultrasonography (PD-US) is a motion-sensitive modality that can display flow characteristics regardless of the direction. This increased motion sensitivity can be used as a parameter to show the tissue motion on artificially generated fremitus images. This study aimed to confirm any signs of incarceration in abdominal wall hernias proven by herniorrhaphy by examination with dynamic PD-US (during manual compression-decompression maneuvers). Twenty-seven patients with anterior abdominal wall hernia with a narrow neck (<1cm in diameter) were examined firstly with gray-scale ultrasonography (GS-US), and then with dynamic PD-US. Two independent radiologists, who were blinded to the real-time images showing the orientation and motion of the hernia neck, completed the examinations. These images were evaluated for any signs of incarceration, as well as the orientation of the hernia neck. Orientations of the hernia neck were not described on GS-US images in 13 lesions and on dynamic PD-US images in 3 lesions. While the GS-US examination revealed incarcerated hernia in four of the patients, the dynamic PD-US examination revealed an additional seven patients with symptoms associated with incarceration. Dynamic PD-US may show the orientation of the hernia neck and any sign of incarceration more accurately and clearly than conventional GS-US. Being informed about these features preoperatively is of utmost importance. Thus, anterior abdominal wall hernias should be examined by dynamic PD-US.

Nodule or Pseudonodule? Differentiation in Hashimoto's Thyroiditis with Sonoelastography

Fine needle aspiration biopsy (FNAB) is the gold standard for the diagnosis of lymphoma in Hashimoto's thyroiditis and is able to differentiate between benign, inflammatory or malignant nodules, classifying them as either true nodules or pseudonodules. This technique is, however, invasive. The present study aimed to differentiate pseudonodules from true nodules by sonoelastography, a non-invasive technique, in 54 patients with Hashimoto's thyroiditis. The accuracy of sonoelastography to differentiate between true or pseudonodules was compared with the gold standard FNAB and with grey scale ultrasonography. The nodules were categorized into three groups: non-demarcated hypoechogenic, demarcated hyperecho genic, and demarcated hypoechogenic. Sono elastography findings were concordant with the cytopathological results and demonstrated that sono elastography was able to detect true thyroid nodules often misdiagnosed by conventional grey scale ultrasonography. Sonoelastography was found to have increased sensitivity for true nodule diagnosis compared with conventional grey scale ultrasonography and may eliminate unnecessary FNABs being carried out.

Comparison of real-time elastography with grey-scale ultrasonography for detection of organ-confined prostate cancer and extra capsular extension: a prospective analysis using whole mount sections after radical prostatectomy

•To evaluate whether transrectal real-time elastography (RTE) improves the detection of intraprostatic prostate cancer (PCa) lesions and extracapsular extension (ECE) compared with conventional grey-scale ultrasonography (GSU). •In total, 229 patients with biopsy-proven PCa were prospectively screened for cancer-suspicious areas and ECE using GSU and RTE. •The largest tumour focus detected by RTE was defined as the index lesion. •The prostate gland was stratified into six sectors on GSU and RTE, which were compared with histopathological whole mount sections after radical prostatectomy. •Histopathologically, PCa was confirmed in 894 out of 1374 (61.8%) evaluated sectors and ECE was identified in 47 (21%) patients. •Of these 894 sectors, RTE correctly detected 594 (66.4%) and GSU 215 (24.0%) cancer suspicious lesions. •Sensitivity was 51% and specificity 72% using RTE compared to 18% and 90% for GSU. •RTE identified the largest side specific tumour focus in 68% of patients. •ECE was identified with a sensitivity of 38% and specificity of 96% using RTE compared to 15% and 97% using GSU. •Compared with GSU, RTE provides a statistically significant improvement in detection of PCa lesions and ECE. •RTE enhances GSU, although improvement is still needed to achieve a clinically meaningful sensitivity.

Use of color flow Doppler ultrasonography to diagnose a bleeding neuroendocrine tumor in the gallbladder of a dog

A 13-year-old neutered female Keeshond-cross was evaluated because of a history of melena, anemia, hematemesis, vomiting, and high serum liver enzyme activities over a 1.5-year period. Abdominal ultrasonography revealed a hyperechoic mass in the gallbladder. In the gallbladder mass itself, a distinct linear blood flow pattern was detected by use of color flow Doppler ultrasonography. A cholecystectomy was performed, and clinical signs resolved. Samples of the mass were examined histologically and immunohistochemically, and findings supported a diagnosis of neuroendocrine tumor of the gallbladder. Tumors of the biliary tree are a potential source of blood loss into the gastrointestinal tract. Color flow Doppler ultrasonography in conjunction with conventional grayscale ultrasonography may be useful in evaluation of the gallbladder in dogs. When echogenic material is detected in the gallbladder, it is important to evaluate the region for blood flow.

1452: Feature of Contrast-enhanced Ultrasound in Clear Cell Renal Cell Carcinoma: Cystic, Hemorrhagic, Debris and Necrotic Tissue and Pseudocapule

To investigate present rate of a pseudocapule and cystic,hemorrhagic,debris and necrotic tissue in clear cell renal cell carcinomas(RCCs) on contrast- enhanced sonography compared with conventional gray-scale sonography. 184 patients with RCCs proved by histologic diagnosis were prospectively studied with contrast-enhanced sonography compared with conventional gray-scale imaging. The present rate of a pseudocapule and cystic,hemorrhagic,debris and necrotic tissue in RCCs was assessed on contrast- enhanced sonography compared with conventional gray-scale sonography. On conventional sonography, the presence of a pseudocapsule was detected in 63 of 184 RCCs. Sonographic contrast-enhanced imaging revealed the in 87 0f 184 RCCs presence of pseudocapsule in 107 0f 184 RCCs (P<0.05). On conventional sonography, the presence of cystic, hemorrhagic, debris and necrotic tissue were seen in 87 0f 184 RCCs. The cystic, hemorrhagic, debris and necrotic tissue were visible in 134 of 184 RCCs. Sonogrphic contrast-ehanced imaging is effective in improving the sonographic visualization of pseudocapsule and cystic, hemorrhagic, debris and necrotic tissue in RCCs. Ultrasonic diagnosis could supply more information in RCCs.

1244: Tissue Harmonic Imaging of Thoracic Benign Lesions: Comparison with Conventional Gray-Scale Sonography

1244: Tissue Harmonic Imaging of Thoracic Benign Lesions: Comparison with Conventional Gray-Scale Sonography

1517: Roles of Color Doppler Imaging During Transrectal Ultrasonography: Pictorial Review

Transrectal ultrasonography (TRUS) examinations have been applied in the prostate, urinary bladder, and distal ureter. During TRUS, color Doppler imaging (CDI) has been used as an adjunct to the conventional gray-scale ultrasonography for improving the accuracy of prostate cancer detection, especially for isoechoic cancers. In addition to the prostate cancer, CDI may also provide important information in the diagnosis of various diseases in prostate, urinary bladder, and distal ureter.

Evaluation of focal fatty infiltration of the liver using color Doppler and contrast‐enhanced sonography

To investigate the vascular characteristics of focal fatty infiltration (FFI) in the liver using color Doppler sonography (CDUS) and contrast-enhanced sonography (CEUS). We prospectively examined 25 areas of FFI of the liver in 20 patients via conventional gray-scale sonography, CDUS, and CEUS. Cadence contrast pulse sequencing and the contrast agent SonoVue were used for CEUS examination. CEUS criteria for diagnosis of FFI were isoenhancement or hypoenhancement in the arterial phase and homogeneous isoenhancement in the portal and late phases. CDUS revealed a draining vein in 4 of 9 (44%) lesions in the hepatic hilum, whereas CEUS revealed a draining vein in 8 (89%) lesions. A vein was associated with the 2 lesions located at the edge of segment II on both CDUS and CEUS. Blood flow was seen on both CDUS and CEUS in the 2 lesions adjacent to the falciform ligament. In one patient, CDUS and CEUS revealed the mid-hepatic vein coursing between 2 FFIs. In the arterial phase of CEUS, the lesions were hypoenhancing in 44% (11/25), iso-enhancing in 44% (11/25), and hyperenhancing in 12% (3/25). In the portal phase and in the late vascular phase, all 25 lesions (100%) were iso-enhancing. Sensitivity of combined sonography and CDUS in the diagnosis of FFI was 44%, and overall accuracy was 81%. The sensitivity of CEUS in the diagnosis of FFI was 88%, and its overall accuracy was 96%. FFI in the porta hepatis is correlated with aberrant venous drainage. FFI around the falciform ligament may be related to divergence of the portal vein or unusual blood supply. In the arterial phase of CEUS, FFI lesions were iso-enhancing as often as they were hypoenhancing.

Ablation of High Intensity Focused Ultrasound Combined with SonoVue on Rabbit VX2 Liver Tumors: Assessment with Conventional Gray-Scale US, Conventional Color/Power Doppler US, Contrast-Enhanced Color Doppler US, and Contrast-Enhanced Pulse-Inversion Harmonic US

We investigated effects of high intensity focused ultrasound (HIFU) combined with contrast agent SonoVue on rabbit VX2 liver tumors by using conventional gray-scale ultrasonography (US), color/power Doppler (CD/PD) US, contrast-enhanced color Doppler (CE CD) US, and contrast-enhanced pulse-inversion harmonic (CE PIH) US. Fourteen days after implantation of VX2 tumors in livers of 50 rabbits, animals were randomly separated into two groups. Based on principles of HIFU, the volume of the tumor was divided into several parallel "planes" to be ablated. Before ablation on each "plane," 0.2 mL SonoVue was injected in bolus via ear veins of rabbits in group II and normal saline solution was administrated in group I. Conventional gray-scale US, CD US, PD US, CE CD US, and CE PIH US were performed before and after ablation. Twenty-three surviving rabbits in each group underwent HIFU ablation. Conventional gray-scale US showed ablated areas diffusely hyperechoic. On CE PIH US, coagulated areas presented perfusion defect. Both conventional gray-scale US and CE PIH US showed the ablated volume in group II was larger than that in group I. CD US and PD US demonstrated residual vessels in periphery ablated areas in group I, but no residual vessels in group II. CE CD US and CE PIH US depicted less residual vessels in periphery ablated areas in group II than that in group I. By enlarging ablated volume of tissue and reducing residual vessels, effects of HIFU ablation on rabbit VX2 liver tumors were enhanced by contrast agent SonoVue.