Xiaodong Zhou

Extracorporeal Ablation of Uterine Fibroids With High-Intensity Focused Ultrasound Imaging and Histopathologic Evaluation

The purpose of this study was to evaluate the therapeutic efficacy of high‐intensity focused ultrasound (HIFU) in the treatment of uterine fibroids by using imaging and histopathologic examination.

Enhancement of ultrasound contrast agent in high-intensity focused ultrasound ablation.

High-intensity focused ultrasound (HIFU) is becoming an increasingly attractive modality for ablation. Enhancement of HIFU is an important issue that has been discussed and investigated worldwide. Ultrasound contrast agents are considered to constitute an efficient medium for changing acoustic characteristics and improving energy deposition in the focal region. The role of microbubbles in inducing enhanced heating, cavitation, and other related events in HIFU ablation has been investigated, with the goal of improving coagulation necrosis volume or decreasing acoustic power and exposure duration. Consequently, with the use of ultrasound contrast agents, applications of HIFU are expected to become more efficient, safe, and accurate and to produce fewer adverse effects. This paper reviews studies that have been conducted to investigate the enhancement of ultrasound contrast agents in HIFU ablation through experiments that were carried out in vitro and in vivo; an analysis of results of this enhancement mechanism is provided.

Clinical utility of contrast-enhanced three-dimensional ultrasound imaging with Sonazoid: Findings on hepatocellular carcinoma lesions

OBJECTIVESnWe investigated clinical utility of contrast-enhanced three-dimensional ultrasound (CE 3D US) imaging with contrast medium Sonazoid for demonstrating characteristic enhancement of hepatocellular carcinoma (HCC).nnnMETHODSnAmong 115 focal liver tumors undergoing CE 3D US imaging, 70 HCCs confirmed with contrast-enhanced multi-detector computed tomography, contrast-enhanced magnetic resonance imaging or histopathologic examination were retrospectively analyzed. CE 3D US imaging was performed using Autosweep 3D scan functionality in the early, middle and late phase, after bolus injection of 0.2 ml Sonazoid. The CE 3D tomographic images reconstructed in parallel slices and sonographic angiogram images were independently reviewed by two reviewers. Kappa values were used to assess inter-reviewers agreement.nnnRESULTSnTUI images showed most of HCCs were detected with intratumoral vessels and early tumor enhancement in the early phase, expressed homogenous or heterogeneous tumor enhancement in the middle phase, and became hypoechoic or isoechoic in the late phase. The kappa values in the early, middle and late phase for inter-reviewer agreements regarding the characteristic enhancement of tumors were 0.817, 0.774, and 0.785. In addition, TUI images demonstrated satellite foci and tortuous tumor vessels in three orthogonal planes. Sonographic angiogram reconstructed by different rendering modes showed the vessels and tumor stain in spatial view. The spatial configuration of anatomic structures was revealed on basis of both TUI and sonographic angiogram images.nnnCONCLUSIONnCE 3D US imaging, with spatial visualization, is clinically useful to exhibit the characteristic enhancement of HCC tumors objectively.

Sonazoid-Enhanced Ultrasonography for Evaluation of the Enhancement Patterns of Focal Liver Tumors in the Late Phase by Intermittent Imaging With a High Mechanical Index

Objective. The purpose of this study was to evaluate the enhancement patterns of focal liver tumors in the late phase of Sonazoid‐enhanced ultrasonography by intermittent imaging with a high mechanical index (MI). Methods. A total of 142 patients with 208 lesions, including 109 hepatocellular carcinomas (HCCs), 61 metastases, 30 hemangiomas, and 8 focal nodular hyperplasias (FNHs), were enrolled in this prospective study. Contrast‐enhanced ultrasonography with intermittent scanning at 2 frames per second (MI, 0.7–1.2) was conducted in the late phase (>5 minutes after bolus intravenous injection of the perflubutane‐based contrast agent Sonazoid; Daiichi Sankyo, Tokyo, Japan). Two blinded readers classified the enhancement patterns of the lesions. The sensitivity, specificity, and positive predictive value (PPV) of the dominant enhancement patterns and inter‐reader agreement were assessed. Results. A combination of diffuse enhancement with intratumoral vessels and intratumoral vessels alone yielded sensitivity of 85% (average of both readers), specificity of 88%, and a PPV of 88% for HCC. For metastasis, a combination of peripheral ringlike enhancement with peritumoral vessels and peripheral ringlike enhancement with intratumoral vessels yielded sensitivity of 79%, specificity of 95%, and a PPV of 85%. For hemangiomas, a combination of peripheral nodular enhancement with peritumoral vessels and peripheral nodular enhancement without peritumoral vessels yielded sensitivity of 75%, specificity of 99%, and a PPV of 92%. Diffuse enhancement with spoked wheel arteries yielded sensitivity of 82%, specificity of 100%, and a PPV of 87% for FNHs. Good inter‐reader agreement was achieved. Conclusions. Sonazoid‐enhanced ultrasonography using intermittent imaging with a high MI can potentially be used for evaluating the enhancement patterns of focal liver tumors in the late phase.

Role of Sonazoid-enhanced three-dimensional ultrasonography in the evaluation of percutaneous radiofrequency ablation of hepatocellular carcinoma

OBJECTIVEnWe investigated contrast-enhanced three-dimensional ultrasonography (CE 3D US) with contrast agent Sonazoid for evaluating the effect of percutaneous radiofrequency (RF) ablation of hepatocellular carcinomas (HCCs).nnnMETHODSn63 HCCs were treated by US-guided percutaneous RF ablation. CE 3D US after bolus injection of 0.2 mL of Sonazoid was performed 5-7 days before and 1 day after RF ablation. CE 3D computed tomography (CT) was performed 5-7 days before and 1 month after the ablation, and during the follow-up period. Multiplanar images in three orthogonal planes and US/CT angiograms were reconstructed on both modalities. Two blinded observers reviewed the images on both modalities to evaluate the ablation effects.nnnRESULTSnAfter RF ablation, the evaluation on CE 3D US and that on CE 3D CT achieved concordance in 61 lesions. Among them, 59 lesions were detected with the absence of tumor vessels and tumor enhancement and evaluated as adequate ablation, and the remaining two lesions were detected with residual tumors. The kappa value for agreement between the findings on the two modalities was 0.65. When 1-month CE 3D CT scans were used as reference standard, the sensitivity, specificity, and accuracy of 1-day CE 3D US for detecting adequate ablation were 97%, 100%, and 97%, respectively.nnnCONCLUSIONnBy demonstrating the ablated areas and residual tumors in three dimensions, CE 3D US with Sonazoid was shown to be useful for evaluating the effect of RF ablation of HCCs, and there was good concordance with the results obtained by CE 3D CT.

Ablation of high-intensity focused ultrasound assisted with SonoVue on Rabbit VX2 liver tumors: sequential findings with histopathology, immunohistochemistry, and enzyme histochemistry.

BackgroundWe investigated sequential effects of HIFU ablation combined with contrast agent SonoVue by using histopathology examination, immunohistochemistry, and enzyme histochemistry.Materials and MethodsForty rabbits with VX2 liver tumors were subjected to HIFU ablation. Before ablation, a bolus injection of 0.2xa0mL SonoVue was administrated in group II (nxa0=xa020), and normal saline solution was injected in group I (nxa0=xa020). On day 0, 3, 7, and 14 after ablation, 5 animals in each group were sacrificed. The tissue in ablated zone, transient zone (within 3xa0mm around ablated area), and surrounding zone (beyond 3xa0mm around ablated area) were collected. Coagulated volume measurement, hematoxylin-eosin staining, immunohistochemistry of Ki 67, Bcl-2, CD54, and MMP-2 to determine cell proliferation and tissue repair, and nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) and succinic dehydrogenase (SDH) staining to evaluate tissue viability were performed.ResultsThe coagulated volume in group II at each time point was larger than that in group I (Pxa0<xa0.05). After day 3, hematoxylin-eosin staining demonstrated necrosis in ablated zones and increasing surrounding fibra bands in group I and group II, while increasing expression of Ki 67, Bcl-2, CD54, and MMP-2 in transient zones was detected using immunohistochemistry in both groups (Pxa0>xa0.05). NADPH-d and SDH staining showed dramatic decrease of enzyme activities in ablated zones immediately after ablation, while residual viable tissues in ablated zones of group II were less than those of group I (Pxa0<xa0.05).ConclusionContrast agent SonoVue enables improvement of HIFU ablation on rabbit VX2 liver tumors.

A comparative study of fibroid ablation rates using radio frequency or high-intensity focused ultrasound.

This study compared the technical success of fibroid devascularization using high-intensity focused ultrasound (HIFU) and radio frequency (RF) to provide an experimental basis for the clinical selection of a suitable, minimally invasive method for treating uterine fibroids. Patients were randomly divided into two groups and treated with HIFU or RF accordingly. The two groups of patients were divided again into subgroups A, B, and C based on fibroid diameter and subgroups A′, B′, and C′ based on fibroid blood supply grades. The fibroid diameters in subgroups A, B, and C were 2.0xa0cmxa0≤xa0Dxa0<xa04.0xa0cm, 4.0xa0cmxa0≤xa0D<6.0xa0cm and 6.0xa0cmxa0≤xa0D<8.0xa0cm, respectively, and fibroid blood supplies were classified into three grades corresponding to subgroups A′, B′, and C′, respectively. The complete ablation rates of the two treatments were compared by contrast-enhanced ultrasound. Both treatments were effective, but the general complete ablation rate of RF was higher than that of HIFU (pxa0<xa00.05). The comparison between the two treatments in subgroup A and subgroup A′ showed that the complete ablation rate of HIFU was as good as that of RF (pxa0>xa00.05). In other subgroups, the complete ablation rates of RF were better than those of HIFU (pxa0<xa00.05). No severe complications were observed after these two treatments. RF can be applied for the majority of fibroids. As a noninvasive therapy, HIFU could be the preferred method for the treatment of small, hypovascular fibroids.

Quantitative Echocardiographic Assessment of Myocardial Acceleration in Normal Left Ventricle by Using Velocity Vector Imaging

To investigate the characteristics of myocardial acceleration in normal left ventricular walls, velocity vector imaging was performed in 30 normal volunteers. Peak accelerations during early systole and early diastole and time to peak acceleration during early systole were calculated for each segment of the standard 16-segment model. A gradient of accelerations from base to apex and a homogeneity of accelerations among different walls at the same level were observed. There were homogeneities of time to peak acceleration during early systole in both longitudinal and latitudinal directions on left ventricular walls. In 82.29% of all segments, the onset of contraction acceleration during early systole could not be identified. Further research with larger populations is needed to clarify the role of myocardial acceleration in the assessment of the site of initial electrical stimulation and the sequence of ventricular depolarization.

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

BackgroundWe 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.MethodsFourteen 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,” 0.2xa0mL 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.ResultsTwenty-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.ConclusionBy enlarging ablated volume of tissue and reducing residual vessels, effects of HIFU ablation on rabbit VX2 liver tumors were enhanced by contrast agent SonoVue.

Non-invasive Vascular Radial/Circumferential Strain Imaging and Wall Shear Rate Estimation Using Video Images of Diagnostic Ultrasound

The aim of this work was to develop a convenient method for radial/circumferential strain imaging and shear rate estimation that could be used as a supplement to the current routine screening for carotid atherosclerosis using video images of diagnostic ultrasound. A reflection model-based correction for gray-scale non-uniform distribution was applied to B-mode video images before strain estimation to improve the accuracy of radial/circumferential strain imaging when applied to vessel transverse cross sections. The incremental and cumulative radial/circumferential strain images can then be calculated based on the displacement field between consecutive B-mode images. Finally, the transverse Doppler spectra acquired at different depths along the vessel diameter were used to construct the spatially matched instantaneous wall shear values in a cardiac cycle. Vessel phantom simulation results revealed that the signal-to-noise ratio and contrast-to-noise ratio of the radial and circumferential strain images were increased by 2.8 and 5.9xa0dB and by 2.3 and 4.4xa0dB, respectively, after non-uniform correction. Preliminary results for 17 patients indicated that the accuracy of radial/circumferential strain images was improved in the lateral direction after non-uniform correction. The peak-to-peak value of incremental strain and the maximum cumulative strain for calcified plaques are evidently lower than those for other plaque types, and the echolucent plaques had higher values, on average, than the mixed plaques. Moreover, low oscillating wall shear rate values, found near the plaque and stenosis regions, are closely related to plaque formation. In conclusion, the method described can provide additional valuable results as a supplement to the current routine ultrasound examination for carotid atherosclerosis and, therefore, has significant potential as a feasible screening method for atherosclerosis diagnosis in the future.