山口 匡

To propose an ultrasound-based parameter for the diagnosis of muscle mass loss (MML) in cirrhosis.This is an IRB-approved cross-sectional study (October 2013 to January 2017) with written informed consent including 357 subjects-234 cirrhosis and 123 controls. MML was diagnosed using the skeletal muscle index at the L3 level (L3-SMI) on computed tomography (CT). Transcutaneous ultrasound was used to demonstrate a cross section of the right iliopsoas muscle, and the iliopsoas muscle index (IP index) was defined by the iliopsoas muscle area/height(2) (mm(2)/m(2)). Receiver operating characteristic (ROC) curve analysis was performed to assess the diagnostic ability of IP index for MML.The iliopsoas muscle was detected in all subjects. The IP index was lower in cirrhosis than in controls: males (211.2 +/- 73.8 vs. 295.5 +/- 139.4, P < 0.0001) and females (200.2 +/- 72.5 vs. 284.4 +/- 112.4, P < 0.0001). L3-SMI and IP index showed correlations in males (r = 0.699, P < 0.0001) and in females (r = 0.707, P < 0.0001). Independent factors for MML by multivariate analysis were body mass index and IP index in both males and females. Sensitivity, specificity, and area under the ROC curve by IP index to detect MML were 79.5%, 73.1%, and 0.835, respectively, with the best cut-off value of 189.2 for males, and 84.6%, 78.8%, and 0.874, respectively, with the best cut-off value of 180.6 for females.Using transcutaneous ultrasound, the IP index may be a valuable diagnostic parameter for MML in cirrhosis.

Relation analysis between physical properties and microstructure of the human tissue has been widely conducted. In particular, the relationships between acoustic parameters and the microstructure of the human brain fall within the scope of our research. In order to analyze the relationship between physical properties and microstructure of the human tissue, accurate image registration is required. To observe the microstructure of the tissue, pathological (PT) image, which is an optical image capturing a thinly sliced specimen has been generally used. However, spatial resolutions and image features of PT image are markedly different from those of other image modalities. This study proposes a modality conversion method from PT image to ultrasonic (US) image including downscale process using convolutional neural network (CNN). Namely, constructed conversion model estimates the US from patch image of PT image. The proposed method was applied to the PT images and we confirmed that the converted PT images were similar to the US images from visual assessment. Image registration was then performed with converted PT and US images measuring the consecutive pathological specimens. Successful registration results were obtained in every pair of the images.

Choosing an appropriate dynamic range (DR) for acquiring radio frequency (RF) data from a high-frequency-ultrasound (HFU) system is challenging because signals can vary greatly in amplitude as a result of focusing and attenuation effects. In addition, quantitative ultrasound (QUS) results are altered by saturated data. In this paper, the effects of saturation on QUS estimates of effective scatterer diameter (ESD) and effective acoustic concentration (EAC) were quantified using simulated and experimental RF data. Experimental data were acquired from 69 dissected human lymph nodes using a single-element transducer with a 26-MHz center frequency. Artificially saturated signals (x(c)) were produced by thresholding the original unsaturated RF echo signals. Saturation severity was expressed using a quantity called saturate-signal-to-noise ratio (SSNR). Results indicated that saturation has little effect on ESD estimates. However, EAC estimates decreased significantly with decreasing SSNR. An EAC correction algorithm exploiting a linear relationship between EAC values over a range of SSNR values and l(1)-norm of xc (i.e., the sum of absolute values of the true RF echo signal) is developed. The maximal errors in EAC estimates resulting from saturation were -8.05, -3.59, and -0.93 dB/mm(3) with the RF echo signals thresholded to keep 5, 6, and 7-bit from the original 8-bit DR, respectively. The EAC correction algorithm reduced maximal errors to -3.71, -0.89, and -0.26 dB/mm3 when signals were thresholded at 5, 6, and 7-bit, respectively.

Purpose: To determine the time-dependent change in strain ratios (SRs) at the healing site of an Achilles tendon rupture in a rabbit model of tendon transection and to assess the correlation between SRs and the mechanical and histologic properties of the healing tissue.Materials and Methods: Experimental methods were approved by the institutional animal care and use committee. The Achilles tendons of 24 New Zealand white rabbits (48 limbs) were surgically transected. The SRs of Achilles tendons were calculated by using compression-based quantitative ultrasonographic elastography measurements obtained 2, 4, 8, and 12 weeks after transection. After in vivo elastography, the left Achilles tendon was harvested for mechanical testing of ultimate load, ultimate stress, elastic modulus, and linear stiffness, and the right tendons were harvested for tissue histologic analysis with the Bonar scale. Time-dependent changes in SRs, mechanical parameters, and Bonar scale scores were evaluated by using repeated-measures analysis of variance. The correlation between SRs and each measured variable was evaluated by using the Spearman rank correlation coefficient.Results: Mean SRs and Bonar scale values decreased as a function of time after transection, whereas mechanical parameters increased (P<.001). SR correlated with ultimate stress (rho=0.68, P<.001,) elastic modulus (rho = 0.74, P<.001), and the Bonar scale (r = 0.87, P<. 001).Conclusion: Quantitative elastography could be a useful method with which to evaluate mechanical and histologic properties of the healing tendon.

Acoustic properties of free fatty acids present in the liver were studied as a possible basis for noninvasive ultrasonic diagnosis of non-alcoholic steatohepatitis. Acoustic impedance was measured for the following types of tissue samples: Four pathologic types of mouse liver, five kinds of FFAs in solvent and five kinds of FFAs in cultured Huh-7 cells. A transducer with an 80-MHz center frequency was incorporated into a scanning acoustic microscopy system. Acoustic impedance was calculated from the amplitude of the signal reflected from the specimen surface. The Kruskal-Wallis test revealed statistically significant differences (p < 0.01) in acoustic impedance not only among pathologic types, but also among the FFAs in solvent and in cultured Huh-7 cells. These results suggest that each of the FFAs, especially palmitate, oleate and palmitoleate acid, can be distinguished from each other, regardless of whether they were in solution or absorbed by cells. (C) 2016 World Federation for Ultrasound in Medicine & Biology.

Recently, the incidence of postoperative pancreatic leakage has been reported to have significantly increased after laparoscopic gastrectomy for gastric cancers in comparison to open surgery. Although their lateral thermal spread has been shown to be smaller than that of other electrosurgical devices, ultrasonically activated surgical devices (USADs) have been suggested as one of the causes. We therefore hypothesized that cavitation generated by USADs could cause injuries to pancreatic tissue. Our retrospective study showed that the amylase activity in the drainage fluid of patients in whom surgery was performed using a USAD with a curved blade was significantly higher than that in patients in whom surgery was performed using a USAD with a straight blade. We therefore focused on the effects of straight and curved USAD blades.The distribution of microbubbles generated in degassed water, which produce mechanical and biological tissue destructive forces, was measured and compared between the two types of USAD.More microbubbles were found to be generated from the side aspect of the curved blade, and the mechanical and biological destructive forces were found to be significantly higher than those generated by the side aspect of the straight blade.These findings strongly suggest that cavitation generated by USADs could injure pancreatic tissues in the clinical cases. Surgeons should be aware of these properties of devices to achieve safe and secure surgeries.

Purpose Chronic liver disease requires careful follow-up during long-term treatment, and development of a quantitative diagnosis method for liver fibrosis based on an ultrasonic imaging system is highly desired.Methods Texture analysis using a co-occurrence matrix was applied to both clinical and simulated ultrasonic images of fibrotic livers. A sequence of matrices was generated for pixel-pair distance, r, and texture feature contrast was chosen to examine the response to r in combination with statistical analysis of echo amplitude distribution using a multi-Rayleigh model.Results The contrast converged with a larger value and fluctuated more significantly in response to r as fibrosis progressed in both the clinical and simulated ultrasonic images. The convergent value rapidly increased at the early stage of fibrosis, and the fluctuation became larger at the advanced stage of fibrosis. Analysis using simulated ultrasonic images with a known fibrous tissue structure theoretically clarified the relationship between contrast behavior and fibrosis progression.Conclusion It was revealed that contrast convergent value and contrast fluctuation provided information on the fibrous tissue structure, and they are expected to be used for quantitative diagnosis of the degree of liver fibrosis.

Background: To examine the influence of the severity of portal hemodynamic abnormality on the prognosis of cirrhosis with respect to the muscle mass loss (MML).Methods: The study involved a subgroup analysis in 98 cirrhosis patients (63.5 +/- 11.8 years) who prospectively underwent both Doppler ultrasound and hepatic venous catheterization. The prognostic influence of MML diagnosed by computed tomography using the L3 skeletal muscle index was evaluated (median observation period, 32.7 months).Results: The cumulative survival rate showed difference between patients with MML (n = 34; 82.2%/1year, 41.2%/3years and 36.1%/5years) and those without (n = 64; 92.1%/1year, 74.9%/3years and 69.4%/5years; P = 0.005). When divided with respect to the portal velocity, the survival rate showed differences between patients with and without MML in the cohort < 12.8 cm/s (n=52, p=0.009) and >= 12.8 cm/s (n= 44, p=0.041). The survival rate also showed differences between patients with MML (n = 24; 78.8%/1year, 40.6%/3years and 34.8%/5years) and those without (n = 45; 91.1%/1year, 71.3%/3years and 63.1%/5years; P = 0.008) in the cohort with hepatic venous pressure gradient (HVPG) > 12 mmHg. However, in the cohort with HVPG <= 12 mmHg, survival rate showed no difference between patients with MML (n= 10; 100%/1year, 61.9%/3years and 61.9%/5years) and those without (n= 19; 93.8%/1year, 71.2%/3years and 59.4%/5years; p = 0.493)Conclusion: Lower HVPG has a compensating effect on the MML-induced poor prognosis of cirrhosis. Care should be taken in the evaluation of the influence of MML in consideration of the severity of portal hypertension.

A method of estimating the size and number density of microbubbles in suspension is proposed, which matches the theoretically calculated frequency dependent attenuation coefficient with the experimental data. Assuming that the size distribution of bubbles is given by a log-normal function, three parameters (expected value and standard deviation of radius and the number density of bubbles) of Sonazoid (R) in the steady flow were estimated. Bubbles are exposed to ultrasound with a center frequency of 5 MHz and mechanical indices of 0.4, 0.5, 0.7, and 1.1. The expected value and standard deviation for the size distribution were estimated to be 70-85 and 45-60% of the reference values in the case of a lower mechanical index, respectively. The number density was estimated to be 20-30 times smaller than the reference values. This fundamental examination indicates that the number density of bubbles can be qualitatively evaluated by the proposed method. (C) 2016 The Japan Society of Applied Physics

To characterize skin ulcers for bacterial infection, quantitative ultrasound (QUS) parameters were estimated by the multiple statistical analysis of the echo amplitude envelope based on both Weibull and generalized gamma distributions and the ratio of mean to standard deviation of the echo amplitude envelope. Measurement objects were three rat models (noninfection, critical colonization, and infection models). Ultrasound data were acquired using a modified ultrasonic diagnosis system with a center frequency of 11 MHz. In parallel, histopathological images and twodimensional map of speed of sound (SoS) were observed. It was possible to detect typical tissue characteristics such as infection by focusing on the relationship of QUS parameters and to indicate the characteristic differences that were consistent with the scatterer structure. Additionally, the histopathological characteristics and SoS of noninfected and infected tissues were matched to the characteristics of QUS parameters in each rat model. (C) 2016 The Japan Society of Applied Physics

In this paper, we propose a technically simple method of destroying a tissue marker composed of giant cluster-like vesicles (GCVs) to facilitate laparoscopic surgeries; the method releases various biological tracers contained in GCVs. An ultrasonically activated device (USAD) emitting 55.5 kHz ultrasound was employed for this purpose. Optical microscopy and fluorospectrophotometry revealed the destruction of GCVs after ultrasound irradiation when the blade tip was set 1.0 mm or closer to, but not directly in contact with, a GCV-containing cell. This means that USAD could be safely used for destroying this GCV tissue marker in clinical settings. (C) 2016 The Japan Society of Applied Physics

Background and AimTo demonstrate the effect of endoscopic injection sclerotherapy (EIS) with argon plasma coagulation (APC) as a primary/secondary prophylaxis for esophageal varies (EV) on portal hemodynamics and long-term outcomes in cirrhosis.MethodsThis prospective study included 48 cirrhotic patients (64.511.4years; 26 bleeders, 22 non-bleeders). Post-treatment outcomes (EIS and APC; median observation period, 12.8months for recurrence and 21.1months for prognosis) were evaluated with respect to the findings of hepatic venous catheterization, Doppler ultrasound, and endoscopic ultrasonography (EUS).ResultsAll patients showed EV eradication after endoscopic treatment, and a decreased frequency of a patent left gastric vein (pre: 83.3%, post: 27.1%, P<0.001). However, hepatic venous pressure gradient (HVPG, mmHg) remained unchanged after the treatment, pre: 16.1 +/- 3.6, post: 15.6 +/- 3.8 (P=0.269). Cumulative variceal recurrence/rebleeding rates were 25.5%/5.6% and 62.4%/23.1% at 1 and 3years, respectively. Post-treatment EUS finding, area of submucosal vessels in the cardia 12mm(2) was the only significant factor for variceal recurrence (hazard ratio 9.769, 95% confidence interval 3.046-31.337; P<0.001). Cumulative recurrence rate was significantly higher in patients with area of submucosal vessels in the cardia 12mm(2) (58.3% at 1year and 100% at 3years) than in those without (11.4% at 1year and 40.9% at 3years, P<0.001). Cumulative overall survival rates were 95.2% and 71.9% at 1 and 3years, respectively, showing no significant relationship with HVPG.ConclusionEIS with APC for EV is unlikely to have a significant influence on portal pressure.

Although there have been several quantitative ultrasound studies on the methods of estimation of scatterer size and acoustic concentration based on the analysis of RF signals for tissue characterization, some problems, e.g., narrow frequency bandwidths and complex sound fields, have limited the clinical applications of such methods. In this report, two types of ultrasound transducer are investigated for the estimation of the scatterer size and acoustic concentration in two glass bead phantoms of different weight concentrations of 0.25 and 2.50% and those in an excised pig liver. The diameters of the glass beads ranged from 5 to 63 mu m with an average of 50 mu m. The first transducer is a single element and the other is a linear phased array. A comparison of the estimations obtained using both transducers gives an insight into how these methods could be applied clinically. Results obtained using the two transducers were significantly different. One of the possible explanations is that beamforming could significantly affect the backscatter coefficient estimation, which was not taken into account. (C) 2015 The Japan Society of Applied Physics

We have been developing a quantitative diagnostic method for liver fibrosis using an ultrasound image. In our previous study, we proposed a multi-Rayleigh model to express a probability density function of the echo amplitude from liver fibrosis and proposed a probability imaging method of tissue characteristics on the basis of the multi-Rayleigh model. In an evaluation using the multi-Rayleigh model, we found that a modeling error of the multi-Rayleigh model was increased by the effect of nonspeckle signals. In this paper, we proposed a method of removing nonspeckle signals using the modeling error of the multi-Rayleigh model and evaluated the probability image of tissue characteristics after removing the nonspeckle signals. By removing nonspeckle signals, the modeling error of the multi-Rayleigh model was decreased. A correct probability image of tissue characteristics was obtained by removing nonspeckle signals. We concluded that the removal of nonspeckle signals is important for evaluating liver fibrosis quantitatively. (C) 2015 The Japan Society of Applied Physics

The aim of this prospective study was to assess the relationship between liver stiffness and hepatic vein waveform patterns in 42 patients with chronic hepatitis and 55 with cirrhosis. Liver stiffness measurement (LSM) values (FibroScan, Echosens, Paris, France) were significantly lower in the triphasic pattern group (11.3 +/- 8.4 kPa) than in the monophasic pattern (32.5 +/- 23.5 kPa, p = 0.001) and biphasic pattern (25.6 +/- 18.1 kPa, p = 0.001) groups, indicating no significant relationship with portal pressure. The ability to diagnose cirrhosis represented by the highest area under the receiver operating characteristic curve was 0.921 (83.6% sensitivity, 90.5% specificity, best cutoff value: 16.9 kPa) by LSM and 1.000 (best cutoff value: 19.4 kPa) by LSM combined with the monophasic pattern. This study revealed a close linkage between liver stiffness and hepatic vein waveform findings, resulting in a better understanding of hepatic vein hemodynamics and wider application of its analysis. (C) 2015 World Federation for Ultrasound in Medicine & Biology.

Background: Imaging is of great importance in diagnosing meniscal tears. The aim of this study was to assess the accuracy of high-resolution ultrasound in the diagnosis of meniscal tears, with arthroscopic examination as the standard reference, after resolution was confirmed with a target-mounted reference phantom. An additional goal was to elucidate the area of the meniscus that could be visualized with the same ultrasound machine after placement of markers into the menisci of cadaveric knees.Methods: Seventy patients were included for the assessment of the accuracy of a high-resolution ultrasound machine with a 14.0 to 6.0-MHz linear transducer. The preoperative ultrasound diagnosis, in terms of the presence and type of tear, was compared with that in the surgical reports. In the cadaveric studies, nine needles were placed in the peripheral zone of the menisci at regular intervals and the number of needles that could be observed with the system was recorded.Results: The overall sensitivity, specificity, positive predictive value, and negative predictive value of ultrasound examination for meniscal tears were 88%, 85%, 85%, and 88%, respectively. These statistical parameters did not differ significantly between the medial and lateral menisci. The sensitivity for diagnosing horizontal, vertical, radial, flap, bucket-handle, and complex tears and for detecting discoid lateral menisci was 83%, 64%, 0%, 64%, 54%, 90%, and 80%, respectively. Ten percent of the lateral menisci could not be evaluated because of poor images. The cadaveric studies revealed that the ultrasound visualized the entire meniscus except for the anterior horn.Conclusions: The findings of this study suggest that ultrasound examination may be suitable for screening for meniscal tears. The fact that almost 10% of the lateral menisci could not be evaluated because of poor images appears to be a weakness of ultrasound.

To evaluate a liver fibrosis quantitatively using an ultrasound B-mode image, it is effective to focus on a probability density function (PDF) of echo amplitudes. In our previous study, a multi-Rayleigh model which is a combination model of Rayleigh distributions with different variances was proposed to express the PDF of echo amplitudes from a fibrotic liver. Using the multi-Rayleigh model, the ultrasound B-mode image can be converted to the fibrotic probability image. To evaluate liver fibrosis quantitatively using the multi-Rayleigh model, a selection of a region of interest (ROI) is important because data such as an abdominal wall and a blood vessel wall are erroneously judged as the fibrotic tissue in the multi-Rayleigh model. In this paper, an automatic selection method of the ROI was examined and ultrasound B-mode images of the fibrotic liver were evaluated using the fibrotic probability images. T he ROI could be selected automatically based on deviations of the PDF of echo amplitudes from the Rayleigh distribution and the multi-Rayleigh model. In the evaluation of fibrotic probability images, the averaged fibrotic probability became large as the progress of liver fibrosis. It was concluded that the progress of liver fibrosis could be evaluated quantitatively using fibrotic probability image based on the mult-iRayleigh model.

To develop a quantitative diagnostic method for liver fibrosis using an ultrasound B-mode image, a probability imaging method of tissue characteristics based on a multi-Rayleigh model, which expresses a probability density function of echo signals from liver fibrosis, has been proposed. In this paper, an effect of non-speckle echo signals on tissue characteristics estimated from the multi-Rayleigh model was evaluated. Non-speckle signals were determined and removed using the modeling error of the multi-Rayleigh model. The correct tissue characteristics of fibrotic tissue could be estimated with the removal of non-speckle signals. (C) 2015 The Authors. Published by Elsevier B.V.

The mechanical and biological effects of ultrasonically activated devices (USADs) were analyzed with two different types of blade and addressed the question of whether USADs could be the direct cause of postoperative pancreatic fistula (POPF) after laparoscopic gastric cancer surgery. A laparoscopic USAD handpiece with a straight blade or a curved blade was used with an appropriate generator. Both devices employ an ultrasonic energy of 55.5 kHz for activation. The blade was activated while its handpiece was fixed on a precision positioning table mounted on a metal framework in all the experiments To determine the independent and combined effects of the activation time, the number of broken foil layers and the site of contact, comparisons between groups were performed by three-way ANOVA followed by multiple comparison testing using the Bonferroni correction. The mean number of broken aluminum foil layers significantly increased as the activation time increased for both types of blade Pairwise comparison of the blade type and contact site revealed a significant difference between straight and curved blades regarding the tip and the side, respectively.

The aim of the study described here was to evaluate the significance of the hepatic filling rate of a perflubutane microbubble agent in predicting long-term outcomes and prognoses in 32 patients with cirrhosis (37-76 y, 20 females, Child-Pugh A16, B16). The time from delivery of the contrast agent to the hepatic artery to maximum enhancement of the liver parenchyma on the sonogram was defined as the hepatic filling rate (mean = 18.6 s). Hepatic filling rate did not correlate significantly with the Child-Pugh score or the model for end-stage liver disease score. However, the survival rate was lower (93.3% at 1 y, 60.2% at 3 y) and the rate of occurrence of hepatocellular carcinoma (HCC) was higher (13.3% at 1 y, 33.3% at 3 y) in the group with the slow filling rate (>= 18 s) than in the group with the rapid filling rate (<18 s) (93.3% at 1 and 3 y for survival, 6.3% at 1 and 3 y for HCC occurrence). Hepatic filling rate may constitute a non-invasive marker for the occurrence of HCC and prognosis of cirrhosis. (E-mail: maru-cib@umin.ac.jp) (C) 2014 World Federation for Ultrasound in Medicine & Biology.

In our previous study, we proposed the multi-Rayleigh model as an amplitude distribution model of fibrotic liver, and succeeded in the quantitative evaluation of liver fibrosis in the region of interest. In this paper, to evaluate liver fibrosis more accurately, the amplitude of each pixel in a clinical echo image was converted to hypoechoic and fibrotic probabilities using the multi-Rayleigh model. Clinical echo images of liver fibrosis were analyzed and the relationship between these probabilities and the stage of liver fibrosis were discussed. We also showed that the information on fibrotic tissue can be extracted more accurately using the fibrotic probability than using the conventional method based on the constant false alarm rate (CFAR) processing. We conclude that the proposed method is valid for the quantitative diagnosis of liver fibrosis. (C) 2014 The Japan Society of Applied Physics

This work investigates the statistics of the envelope of three-dimensional (3D) high-frequency ultrasound (HFU) data acquired from dissected human lymph nodes (LNs). Nine distributions were employed, and their parameters were estimated using the method of moments. The Kolmogorov Smirnov (KS) metric was used to quantitatively compare the fit of each candidate distribution to the experimental envelope distribution. The study indicates that the generalized gamma distribution best models the statistics of the envelope data of the three media encountered: LN parenchyma, fat and phosphate-buffered saline (PBS). Furthermore, the envelope statistics of the LN parenchyma satisfy the pre-Rayleigh condition. In terms of high fitting accuracy and computationally efficient parameter estimation, the gamma distribution is the best choice to model the envelope statistics of LN parenchyma, while, the Weibull distribution is the best choice to model the envelope statistics of fat and PBS. These results will contribute to the development of more-accurate and automatic 3D segmentation of LNs for ultrasonic detection of clinically significant LN metastases. (C) 2014 The Japan Society of Applied Physics

We performed detailed analysis of nickel suicide discontinuities induced by agglomeration, which causes the increased electric resistance in high-performance complementary metal oxide semiconductor devices, by using advanced physical analysis techniques: transmission electron microscopy (TEM), scanning electron microscopy (S EM) electron backscatter diffraction (EBSD) analysis, and three-dimensional atom-probe (AP) analysis. We confirmed that the agglomeration of the nickel suicide is related to elongated-triangular-shaped splits, which cause discontinuities that occur at low-angle grain boundaries pinned by boron clusters even with small stress. We successfully determined the formation mechanism of these nickel suicide discontinuities in detail. (C) 2014 The Japan Society of Applied Physics

Goals/Background:The aim was to determine the influence of the paraumbilical vein (PUV) patency and its effect on the portal hemodynamics and clinical presentations in cirrhotic patients.Study:In this prospective study of 181 cirrhotic patients (101 males, 80 females; aged 62.611.8 y), the portal hemodynamics were assessed using Doppler ultrasonography.Results:The incidence of patent PUV was 26.0% (47/181). The mean flow volume in the portal trunk, the incidence of a left gastric vein with hepatofugal flow, and the grade of the esophageal varices were significantly higher in the patients with a patent PUV (908.2 mL/min, 70.2%, 9 with none to small, and 27 with medium to large, respectively) than in those without (771.7 mL/min, 48.5%, 57 with none to small, and 48 with medium to large, respectively). The hepatic venous pressure gradient and the wedged hepatic venous pressure (mm H2O) were significantly higher in the former group (268.0 +/- 89.7 and 389.5 +/- 99.9, respectively) than in the latter (203.5 +/- 63.2 and 317.7 +/- 67.7, respectively). The deterioration of ascites during the 2-year follow-up period was significantly more often in the patients with a patent PUV (4/12, 33.3%) than in those without. The cumulative survival rates at 1, 2, and 3 years were similar between the 2 groups: 92.5%, 92.5%, and 82.4%, respectively, in the former and 90.7%, 83.8%, and 76.3%, respectively, in the latter.Conclusions:A patent PUV seems to signify pressure-loaded portal hemodynamics in cirrhotic patients. However, it seems to have little effect on their prognoses.

In laparoscopic surgery, to identify the location of lesions and blood vessels inside organs, an ultrasound probe which can be inserted through small incision is used. However, since surgeons must observe the laparoscopic and ultrasound images both at the same time, it is difficult to understand the correspondence between the ultrasound image and real space. Therefore, to recognize the correspondence between these two images intuitively, we developed a system for overlaying ultrasound image on the laparoscopic image. Since the tip of the probe is flexed freely, we acquired the probe tip position and orientation using a method for detecting the probe angle from laparoscopic image and information obtained from optical tracking sensor. As a result of an experiment using a wire phantom, overlaying error of ultrasound images was found to be 0.97 mm. Furthermore, the rate of probe angle detection was evaluated through an animal experiment to be 83.1%.

To realize a quantitative diagnosis method of liver fibrosis, we have been developing a modeling method for the probability density function of the echo amplitude. In our previous study, we proposed a multi-Rayleigh model with two or three Rayleigh distributions, which is considered as a heterogeneous medium consisting of normal and different tissue, and constructed the evaluation method using modified quantile-quantile probability plot (Q-Q plot). In this study, we examined a multi-Rayleigh model and generalized Nakagami model which is general technique, corresponding to the distribution of the echo amplitude from homogeneous and heterogeneous medium. In clinical data of liver fibrosis, we showed validity of proposed model.

Background and AimThis study examined the natural history of postvascular-phase iso-enhanced lesions (PIELs) on contrast-enhanced sonograms to determine the potential risk and predictive factors for developing hepatocellular carcinoma (HCC) in chronic liver diseases.MethodsThis prospective study included 87 PIELs on contrast-enhanced sonograms (postvascular-phase: 10min post-injection of perflubutane microbubbles) in 72 patients with chronic liver diseases (45 males and 27 females; age 65.010.8y; PIEL diameter 12.54.2mm). The PIELs were followed up by ultrasound/contrast-enhanced ultrasound, computed tomography, or magnetic resonance imaging at 3 to 6 months intervals.ResultsTwenty patients developed HCCs during the study period (median, 22.0 months). The cumulative risk of HCC occurrence was 7.9% at 1 year and 36.0% at 3 years. The presence of coexistent HCC (hazard ratio [HR], 4.975; 95% confidence interval [CI], 1.729-14.316; P=0.003) and alpha-fetoprotein>20ng/mL (HR, 4.104; 95% CI, 1.621-10.392; P=0.003) were significant factors for the risk of HCC occurrence. Fourteen of these lesions were diagnosed as HCCs that developed from iso-enhanced lesions. Cumulative HCC occurrence rates from PIEL>14mm was 23.5% at 1 year and 46.3% at 3 years. Cox regression analysis showed that PIEL>14mm (HR, 6.780; 95% CI, 2.060-22.32; P=0.002) and alpha-fetoprotein>20ng/mL (HR, 4.892; 95% CI, 1.559-15.350; P=0.007) were statistically significant factors for HCC occurrence.ConclusionsPatients with coexistent HCC, alpha-fetoprotein>20ng/mL, or PIEL>14mm should be carefully monitored because of the high potential for HCC occurrence.

To realize a quantitative diagnosis method of liver fibrosis, we have been developing a modeling method for the probability density function of the echo amplitude. In our previous model, the approximation accuracy is insufficient in regions with hypoechoic tissue such as a nodule or a blood vessel. In this study, we examined a multi-Rayleigh model with three Rayleigh distributions, corresponding to the distribution of the echo amplitude from hypoechoic, normal, and fibrous tissue. We showed quantitatively that the proposed model can model the amplitude distribution of liver fibrosis echo data with hypoechoic tissue adequately using Kullback-Leibler (KL) divergence, which is an index of the difference between two probability distributions. We also found that fibrous indices can be estimated stably using the proposed model even if hypoechoic tissue is included in the region of interest. We conclude that the multi-Rayleigh model with three components can be used to evaluate the progress of liver fibrosis quantitatively. (C) 2013 The Japan Society of Applied Physics

Electrothermal bipolar vessel sealing devices have been used for the ligation of vessels during surgical procedures. However, unexpected bleeding is still reported, the cause of which is not yet clarified by conventional histopathological analysis. In the present study, ultrasonic microscopy with a central frequency of 80MHz was applied to evaluate the mechanical properties of ligated vessels. Five arteries and five veins were electrically sealed for 0, 2, 4, 6, and 8 s. The speed of sound in the native adventitia were higher than that in the media. The speed of sound was not correlated with sealing time. However, acoustical inhomogeneity was seen in the sealed vessels. Thus, the acoustical properties of vessels may be affected by the electrothermal effect, and the evaluation of mechanical properties is important for assessing the tissue sealing performance. (c) 2013 The Japan Society of Applied Physics

Purpose: Detection of metastases in lymph nodes (LNs) is critical for cancer management. Conventional histological methods may miss metastatic foci. To date, no practical means of evaluating the entire LN volume exists. The aim of this study was to develop fast, reliable, operator-independent, high-frequency, quantitative ultrasound (QUS) methods for evaluating LNs over their entire volume to effectively detect LN metastases.Methods: We scanned freshly excised LNs at 26 MHz and digitally acquired echo-signal data over the entire three-dimensional (3D) volume. A total of 146 LNs of colorectal, 26 LNs of gastric, and 118 LNs of breast cancer patients were enrolled. We step-sectioned LNs at 50-mu m intervals and later compared them with 13 QUS estimates associated with tissue microstructure. Linear-discriminant analysis classified LNs as metastatic or nonmetastatic, and we computed areas (Az) under receiver-operator characteristic curves to assess classification performance. The QUS estimates and cancer probability values derived from discriminant analysis were depicted in 3D images for comparison with 3D histology.Results: Of 146 LNs of colorectal cancer patients, 23 were metastatic; Az = 0.952 +/- 0.021 (95% confidence interval [CI]: 0.911 0.993); sensitivity = 91.3% (specificity = 87.0%); and sensitivity 100% (specificity-67.5%). Of 26 LNs of gastric cancer patients, five were metastatic; Az = 0.962 + 0.039 (95% CI: 0.807-1.000); sensitivity = 100% (specificity = 95.3%). A total of 17 of 118 LNs of breast cancer patients were metastatic; Az = 0.833 +/- 0.047 (95% CI: 0.741-0.926); sensitivity = 88.2% (specificity = 62.5%); sensitivity = 100% (specificity = 50.5%). 3D cancer probability images showed good correlation with 3D histology.Conclusions: These results suggest that operator-and system-independent QUS methods allow reliable entire-volume LN evaluation for detecting metastases. 3D cancer probability images can help pathologists identify metastatic foci that could be missed using conventional methods. (C) 2013 Elsevier Inc. All rights reserved.