Objective parameters in magnetic resonance imaging (MRI) for neuromuscular diagnosis: preliminary findings.

T1 relaxation time (T1 time), T2 relaxation time (T2 time), and proton (rho) density in the thigh muscles of 20 normal healthy volunteers and three patients with muscle atrophy in the lower extremity were measured in order to select the useful MRI parameters for neuromuscular diagnosis. Since the standard deviation (SD) of both T1 and T2 times in each muscle was found to be within a relatively small range, these values were expected to be useful MRI parameters for neuromuscular diagnosis. On the contrary, rho density was not a valid parameter for diagnosis, as it was demonstrated to have large SDs in the muscles. The differences of these parameters in the three patients also supported the fact that MRI was useful for discriminating between the various types of muscular abnormalities based on relaxation times. The longer T1 and T2 times in women suggested that the content of water in skeletal muscle was higher in women than in men. Moreover, the T1 time in the dominant limbs was found to be shorter than in the non-dominant limbs for rectus femoris only in both men and women, while there were no differences in T2 time in these muscles.     

Quantifying the effect of hand preference on upper limb bone mineral and soft tissue composition in young and elderly women by dual-energy X-ray absorptiometry

Summary. The purpose of this study was to quantify the effect that hand preference has on upper limb bone mineral and soft tissue composition in healthy young and elderly women. Bone mineral content (BMC) in grams, bone mineral density (BMD) in g cm^-2, fat-free soft tissue (FFST) in grams, fat tissue (g), and percent fat were determined by dual-energy X-ray absorptiometry (DXA) for dominant and non-dominant upper limbs as well as total body fat (%) in 25 young (26–6 ± 4–3 years, mean ± SD) and 35 elderly women (68–4 ± 2–9 years). For both groups, the dominant upper limb had a greater BMC (P<0–001), BMD (young, P<0001; elderly, P<0–05), and FFST mass (P<0–001), and a lower percent fat (young, P<0–01; elderly, P<0–05) than the non-dominant limb; however, there was no difference between limbs for total fat mass. BMC, BMD, and FFST in the dominant limb of young women were 7–1%, 1–8%, and 5–1% greater than the non-dominant limb, while for older women the differences were 5–3%, 10%, and 4–2%. Relative fat of the dominant limb was 3–0% and 1 -3% less than the non-dominant limb for young and older women, respectively. Age did not affect the percent bone mineral or soft tissue difference. A higher bone mineral and FFST mass in the dominant limb is expected due to the greater activity demands placed upon these tissues. However, a larger bone and FFST mass increases the total mass of the dominant limb, resulting in a dilution of the fat tissue mass and hence a reduced fat percent for the limb. This study indicates that hand preference affects the tissue composition of the upper limb in both young and elderly women, resulting in an increased bone mineral and FFST mass with no change in absolute fat mass. Hand preference should be taken into account when upper limb bone mineral and/or soft tissue composition is assessed.     

化学饱和法脂肪抑制MRI肝脏信号衰减的机制及意义

目的 探讨化学饱和法脂肪抑制MRI肝脏信号衰减的机制及意义。方法 家兔，人非脂肪肝与脂肪肝均以化学饱和法脂肪抑制和非脂肪抑制序列扫描，测量脂肪抑制前后肝脏的信号强度并计算其衰减率（SIAR），肝中脂滴占肝脏单位体积的百分比（Vv值）。结果 所有对象脂肪抑制后肝脏信号强度均有明显衰减，但轻，中度脂肪肝组和非脂肪肝组的SIAR间无显著性差异。SIAR和Vv值相关性不高。结论 化学饱和法脂肪抑制MRI对脂肪组织信号的抑制呈相对非特异性。     

3.0TMRI弥散加权成像评价腰椎间盘退变原因的价值

背景：MR 弥散加权成像对水分子的扩散运动敏感,能早期了解椎间盘纤维环和髓核的含水量改变,从而明确其退变程度。 目的：通过对109例腰椎间盘的弥散加权成像进行前瞻性研究,旨在提高应用MRI中弥散加权成像序列对椎间盘退变程度和早期变性诊断的认识。 方法：采用Siemens Verio 3.0T 超导磁共振仪。常规平扫包括矢状位T1WI序列及T2WI抑脂序列;弥散加权成像采用SE-EPI序列行矢状位扫描,取b值为800s/mm2,层厚、间距和显示野同T2WI抑脂序列扫描。根据Pfirrmann等的椎间盘退变分级标准,采用盲法在矢状位T2WI上对符合纳入标准的109例545个腰椎间盘进行分级。将弥散加权成像数据传至工作站,并对表观扩散系数图像进行测量,得到表观扩散系数值。分别画出L1/2-L5/S1椎间盘的感兴趣区,记录数据。 结果与结论：年龄与椎间盘退变分级存在明显相关性,年龄越大高级别数量越多。椎间盘表观扩散系数值影响因素分析：男性与女性各椎间盘表观扩散系数值之间差异无显著性意义（P〉0.05）。L1-S1各椎间盘年龄与表观扩散系数值之间存在负相关（P 〈0.05）;椎间盘评级与表观扩散系数值之间存在负相关（P 〈0.05）。提示通过对表观扩散系数值的研究,弥散加权成像将会成为椎间盘退行性变诊断、特别是椎间盘早期退变、无创评价治疗效果及预后判断的重要技术手段。     

Tissue-mimicking phantom materials with tunable optical properties suitable for assessment of diffuse reflectance spectroscopy during electrosurgery

Emerging intraoperative tumor margin assessment techniques require the development of more complex and reliable organ phantoms to assess the performance of the technique before its translation into the clinic. In this work, electrically conductive tissue-mimicking materials (TMMs) based on fat, water and agar/gelatin were produced with tunable optical properties. The composition of the phantoms allowed for the assessment of tumor margins using diffuse reflectance spectroscopy, as the fat/water ratio served as a discriminating factor between the healthy and malignant tissue. Moreover, the possibility of using polyvinyl alcohol (PVA) or transglutaminase in combination with fat, water and gelatin for developing TMMs was studied. The diffuse spectral response of the developed phantom materials had a good match with the spectral response of porcine muscle and adipose tissue, as well as in vitro human breast tissue. Using the developed recipe, anatomically relevant heterogeneous breast phantoms representing the optical properties of different layers of the human breast were fabricated using 3D-printed molds. These TMMs can be used for further development of phantoms applicable for simulating the realistic breast conserving surgery workflow in order to evaluate the intraoperative optical-based tumor margin assessment techniques during electrosurgery.     

An automated method for measuring static pressure-volume curves of the respiratory system and its application in healthy lungs and after lung damage by oleic acid infusion

Elastic pressure/volume (PV) curves of the respiratory system have attracted increasing interest, because they may be helpful to optimize ventilator settings in patients undergoing mechanical ventilation. Clinically applicable methods need to be fast, use routinely available equipment, draw the inspiratory and expiratory PV curve limbs, separate the resistive and viscoelastic properties of the respiratory system from the elastic properties, and provide reproducible measurements. This paper presents a computer-controlled method for rapid measurements of static PV curves using a long inflation-deflation with pauses, and its evaluation in six pigs before and after lung damage caused by oleic acid. The method is fast, i.e. 20.5 +/- 1.9 s (mean +/- SD) in healthy lungs and 17.7 +/- 4.1 s in diseased lungs, this including inspiratory and expiratory pauses of 1.1 s duration. In addition the only equipment used was a clinical ventilator and a PC. For healthy and damaged lungs expiratory PV curve limbs were very reproducible and were at higher volume than the inspiratory limbs, indicating hysteresis. For damaged lungs inspiratory PV limbs were reproducible. For healthy lungs the inspiratory limbs were reproducible but only after the first inflation-deflation. It is possible that during the first inflation alveoli are recruited which are not derecruited on deflation, shifting the inspiratory limb of the PV curve. The paused long inflation-deflation technique provides a quick, automated measurement of static PV curves on both inspiratory and expiratory limbs using routinely available equipment in the intensive care unit.     

Parvalbumin gene transfer impairs skeletal muscle contractility in old mice

Abstract Sarcopenia is the progressive age-related loss of skeletal muscle mass associated with functional impairments that reduce mobility and quality of life. Overt muscle wasting with sarcopenia is usually preceded by a slowing of the rate of relaxation and a reduction in maximum force production. Parvalbumin (PV) is a cytosolic Ca(2+) buffer thought to facilitate relaxation in muscle. We tested the hypothesis that restoration of PV levels in muscles of old mice would increase the magnitude and hasten relaxation of submaximal and maximal force responses. The tibialis anterior (TA) muscles of young (6 month), adult (13 month), and old (26 month) C57BL/6 mice received electroporation-assisted gene transfer of plasmid encoding PV or empty plasmid (pcDNA3.1). Contractile properties of TA muscles were assessed in situ 14 days after transfer. In old mice, muscles with increased PV expression had a 40% slower rate of tetanic force development (p<0.01), and maximum twitch and tetanic force were 22% and 16% lower than control values, respectively (p<0.05). Muscles with increased PV expression from old mice had an 18% lower maximum specific (normalized) force than controls, and absolute force was ～26% lower at higher stimulation frequencies (150-300?Hz, p<0.05). In contrast, there was no effect of increased PV expression on TA muscle contractile properties in young and adult mice. The impairments in skeletal muscle function in old mice argue against PV overexpression as a therapeutic strategy for ameliorating aspects of contractile dysfunction with sarcopenia and help clarify directions for therapeutic interventions for age-related changes in skeletal muscle structure and function.     

6个腓骨肌萎缩症1A型家系临床分析

目的 探讨腓骨肌萎缩症(Charcot-Marie-Tooth disease,CMT)1A型的临床表现、神经电生理和肌肉MRI特点.方法 回顾性分析6个CMT1A型家系中6例先证者及2例家系成员的临床资料、神经电生理特点和下肢肌肉的MRI影像学特征.结果 6例CMT1A型先证者的首发症状以双下肢无力为主,主要临床特征...     

Forearm composition and muscle function in trained and untrained limbs

Summary. The influence of a period of training, which lasts for several years, on the proportions of muscle, fat and bone present in the human forearm has been investigated by comparing trained and untrained limbs of nine experienced male tennis players. Ten healthy but untrained males of similar age served as a control group. Computed tomography (CT) scans of the forearm were made at intervals along its length to identify fat, muscle and bone and to calculate the volumes occupied by each of these components. Total forearm volume was greater in the dominant limb compared with the contralateral side in both trained (by 135±59 cm³, mean±SD, P<0·001) and untrained subjects (by 41±45 cm³, P<0·02). Forearm muscle volume was also greater in dominant limbs of trained (by 117±52 cm³, P<0·001) and untrained by 35±41 cm³, P<0·025) subjects. Muscle accounted for 75·4±2·7% of the total volume in the dominant arm of trained subjects compared with 71·4±4·2% in the control group (P<0·05). There was a greater proportion of muscle (P<0·05) and a smaller proportion of fat (P<0·001) in the trained limb compared with the contralateral limb of the same subjects. No differences in proportions of fat, muscle and bone were observed in dominant and non-dominant limbs of the control subjects. Trained subjects were able to exert a greater isometric force with the dominant limb (549±76N) than with the non-dominant limb (496±48N; P<0·005). There was no difference in grip strength between the arms of the untrained group (dominant: 516±107N; non-dominant: 491±91N). The ratio of strength to muscle volume was, however, the same in dominant and non-dominant arms of both groups of subjects.     

Quantitative Ultrasound Imaging to Assess the Biceps Brachii Muscle in Chronic Post-Stroke Spasticity: Preliminary Observation

We prospectively investigated the feasibility of using quantitative ultrasound imaging (QUI) to assess the biceps brachii muscle (BBM) in individuals with chronic post-stroke spasticity. To quantify muscle echogenicity and stiffness, we measured QUI parameters (gray-scale pixel value and shear wave velocity [SWV, m/s]) of the BBM in three groups: 16 healthy BBMs; 12 post-stroke, non-spastic BBMs; and 12 post-stroke, spastic BBMs. The QUI results were compared with the Modified Ashworth Scale and Tardieu Scale. A total of 20 SWVs were measured in each BBM, once at elbow in 90° flexion and again at maximally achievable extension using acoustic radiation force impulse imaging. BBM pixel value was measured in gray-scale images captured at 90° elbow flexion using ImageJ software. Statistical analyses included analysis of variance for examining the difference in SWV and pixel values among the three groups; Bonferroni correction for testing the difference in SWV and pixel values in a paired group; t-test for examining the difference in SWV values measured at two elbow angles; and Pearson correlation coefficient for analyzing the correlation of QUI to Modified Ashworth Scale and Tardieu Scale. SWV significantly differed between spastic BBMs and non-spastic or healthy BBMs. For pixel values, each of the three groups significantly differed from the others at elbow 90° flexion. The difference in SWV measured between the two elbow angles was also significant (p?<0.01). A strong negative correlation was found between SWV and passive range of motion (R²?=??0.88, p?<0.0001) in spastic upper limbs. These results suggest that the use of QUI is feasible in quantitative assessment of spastic BBM.     

Length and circumference measurements in one-joint and multijoint muscles in rabbits after immobilization

In this article, we compared changes in the length and circumference of the soleus and the plantaris muscles in rabbits. The rabbits were assigned to a nonimmobilized external control group (n = 4), an experimental shortened-position group (n = 10), or an experimental lengthened-position group (n = 9). One hind limb of each animal in the experimental groups was immobilized in a cast for four weeks to put the muscles in either a shortened or lengthened position. The contralateral limb served as an internal control for the animals in the experimental groups. After the immobilization period, the limbs were fixed in situ, the muscles were dissected, and length and circumference measurements were taken. In both experimental conditions, the immobilized soleus muscles were shorter than their contralateral counterparts (p less than .05); the length of the plantaris muscles did not change. The immobilized muscles had decreased circumference values regardless of the immobilization angle. When compared with the control condition, the shortened soleus muscles had a greater decrease in circumference than did the plantaris muscles. More connective tissue was observed in the muscle bellies of the soleus after immobilization than in the plantaris. Similar significant changes (p less than .05) were found in the nonimmobilized limbs of the animals in the experimental groups. Specifically, the soleus muscles demonstrated length and circumference changes, whereas the plantaris muscles showed changes only in circumference. These findings suggest that when a weight-bearing limb is immobilized, adaptations in gross muscle length and circumference are to be expected in the involved and uninvolved limbs. An assessment of similar adaptations in humans should be a part of the evaluation during recovery.     

Locally adaptive super-resolution waterline mapping with MODIS imagery

Mapping inland water bodies is important for relevant research fields and water resource management. Satellite remote sensing is a routine approach, and various remotely sensed images have been applied to map waterlines. MODerate-resolution Imaging Spectroradiometer (MODIS) images have advantages for waterline mapping in large areas, thanks to its wide scan width and high frequent revisiting period; however, the spatial resolution of MODIS images is too coarse to map waterlines accurately. In this article, a super-resolution mapping (SRM) model was proposed for fine spatial resolution waterline mapping with MODIS images. The proposed SRM model was directly applied in the MODIS band 2 images, which have a fine spatial resolution and a high spectral separability between water and land. In order to further take account of the spatial heterogeneity of endmembers, the reflectance values of water and land were locally calculated for each coarse resolution pixel. The proposed SRM model was assessed in two study areas located in the Tibetan Plateau, China and Wisconsin, United States, including water bodies with different areas and boundary shapes. The results showed that the accuracy values of the proposed SRM model using local endmembers were higher than those of hard classification and the SRM model using average endmembers, showing the effectiveness of the proposed model in fine spatial resolution waterline mapping with MODIS imagery.     

Deconvolution-based partial volume correction in Raclopride-PET and Monte Carlo comparison to MR-based method

In this work, we evaluated three iterative deconvolution algorithms and compared their performance to partial volume (PV) correction based on structural imaging in brain positron emission tomography (PET) using a database of Monte Carlo-simulated images. We limited our interest to quantitative radioligand PET imaging, particularly to (11)C-Raclopride and striatal imaging. The studied deconvolution methods included Richardson-Lucy, reblurred Van Cittert, and reblurred Van Cittert with the total variation regularization. We studied the bias and variance of the regional estimates of binding potential (BP) values and the accuracy of regional TACs as a function of the applied image processing. The resolution/noise tradeoff in parametric BP images was addressed as well. The regional BP values and TACs obtained by deconvolution were almost as accurate than those by structural imaging-based PV correction (GTM method) when the ideal volumes of interests (VOIs) were used to extract TACs from the images. For deconvolution methods, the ideal VOIs were slightly eroded from the exact anatomical VOI to limit the bias due to tissue fraction effect which is not corrected for by deconvolution-based methods. For the GTM method, the ideal VOIs were the exact anatomical VOIs. The BP values and TACs by deconvolution were less affected by segmentation and registration errors than those with the GTM-based PV correction. The BP estimates and TACs with deconvolution-based PV correction were more accurate than BPs and TACs derived without PV correction. The parametric images obtained by the deconvolution-based PV correction showed considerably improved resolution with only slightly increased noise level compared to the case with no PV correction. The reblurred Van Cittert method was the best of the studied deconvolution methods. We conclude that the deconvolution is an interesting alternative to structural imaging-based PV correction as it leads to quantification results of similar accuracy, and it is less prone to registration and segmentation errors than structural imaging-based PV correction. Moreover, PV-corrected parametric images can be readily computed based on deconvolved dynamic images.     

Generalized pixel profiling and comparative segmentation with application to arteriovenous malformation segmentation

Extraction of structural and geometric information from 3-D images of blood vessels is a well known and widely addressed segmentation problem. The segmentation of cerebral blood vessels is of great importance in diagnostic and clinical applications, with a special application in diagnostics and surgery on arteriovenous malformations (AVM). However, the techniques addressing the problem of the AVM inner structure segmentation are rare. In this work we present a novel method of pixel profiling with the application to segmentation of the 3-D angiography AVM images. Our algorithm stands out in situations with low resolution images and high variability of pixel intensity. Another advantage of our method is that the parameters are set automatically, which yields little manual user intervention. The results on phantoms and real data demonstrate its effectiveness and potentials for fine delineation of AVM structure.     

Investigation of hand muscle atrophy in stroke survivors

Background

Weakness is often profound in the contralesional hand after stroke. Relative contributions of various neural and mechanical mechanisms to this impairment, however, have not been quantified. In this study, the extent of one potential contributor, muscle atrophy, was noninvasively assessed in index finger musculature using ultrasonographic techniques.

Methods

Twenty-five stroke survivors (45–65 years old) with severe hand impairment resulting from a stroke occurring 2–4 years prior participated, along with 10 age-matched control subjects. Muscle cross sectional area and thickness were geometrically measured from ultrasound images on both limbs of participants.

Findings

Muscle size on the paretic limb of stroke survivors was smaller for all 7 hand muscles investigated. An average difference of 15% (SD 4) was seen for muscle cross sectional area and 11% (SD 2) for muscle thickness, while the difference between the dominant and non-dominant limbs for control subjects (6% (SD 2) and 1% (SD 4) for the muscle cross sectional area and muscle thickness, respectively) was not significant.

Interpretation

Although muscle atrophy was detected in the paretic limb following stroke, it is not explanatory of the marked impairment in strength seen in this stroke population. However, other alterations in muscle morphology, such as fatty infiltrations and changes in fiber structure, may contribute to the emergent muscle weakness post-stroke.     

磁共振检查对胃癌术前TNM分期的价值

目的：分析磁共振(MR)检查对胃癌术前分期的价值，并与病理结果对照。方法：42例经胃镜诊断的胃癌患，于术前1周内行MR(SIGNA 1.5)检查，术后将病理与术前诊断相对照。MR扫描的序列包括FSET1W、FSET2W、FSET1W加脂肪抑制以及动态FSPGR加脂肪抑制增强扫描，所有数据均行统计检验，使用统计软件SAS完成。结果：MR对胃癌浸润深度(T)判断与手术病理比较的准确率分别为T1 88．8％(5／6)、T2.70％(7／10)、T3 86．8％(13／15)、T4 100％(11／11)。MR动态增强加脂肪抑制以及延迟扫描对于早期病变的显示、区分T2与T3、T3与T4以及邻近组织的侵犯都有着优势。MR对胃癌术前N分期的判断准确率为61.9％(26／42)，其中N0 63．6％(7／11)、N1 61．9％(13／21)、N2 60．0％(6／10)。MR检出M准确率达到83.3％(6／7)。结论：MR检测对胃癌术前分期具有一定的优势．特别是判断肿瘤浸润深度有相当的准确性的，但对于淋巴结的判定仍存在缺陷．     

Characterizing Viscoelastic Polyvinyl Alcohol Phantoms for Ultrasound Elastography

Ultrasound phantoms mimic the acoustic and mechanical properties of native tissues. Polyvinyl alcohol (PVA) phantoms are used extensively as models for validating ultrasound elastography approaches. However, the viscous properties of PVA phantoms have not been investigated adequately. Glycerol is a viscous liquid that has been reported to increase the speed of sound of phantoms. This study aims to assess the acoustic and viscoelastic properties of PVA phantoms and PVA mixed with glycerol at varying concentrations. The phantoms were fabricated with 10% w/v PVA in water with varying concentrations of glycerol (10%, 15% and 20% v/v) and 2% w/v silicon carbide particles as acoustic scatterers. The phantoms were subjected to either one, two, or three 24-h freeze–thaw cycles. The longitudinal sound speeds of all PVA phantoms were measured, and ranged from 1529 to 1660 m/s. Attenuation spectroscopy was performed in the range of 5 to 20 MHz. The measured attenuation followed a power-law relationship with frequency, wherein the power-law fit constants and exponents ranged from 0.02 to 0.1 dB/cm/MHzⁿ and from 1.6 to 1.9, respectively. These results were in agreement with previous reports for soft tissues. Viscoelasticity of PVA phantoms was assessed using rheometry. The estimated values of shear modulus and viscosity using the Kelvin–Voigt and Kelvin–Voigt fractional derivative models were within the range of previously-reported tissue-mimicking phantoms and soft tissues. The number of freeze-thaw cycles were shown to alter the viscosity of PVA phantoms, even in the absence of glycerol. Scanning electron microscopy images of PVA phantoms without glycerol showed a porous hydrogel network, in contrast to those of PVA-glycerol phantoms with non-porous structure. Phantoms fabricated in this study possess tunable acoustic and viscoelastic properties within the range reported for healthy and diseased soft tissues. This study demonstrates that PVA phantoms can be manufactured with glycerol for applications in ultrasound elastography.     

正常成人活体鼻咽咀嚼肌间隙的MRI研究

目的探讨成人活体鼻咽咀嚼肌间隙内正常结构在MRI上的显示情况。方法观察40例健康志愿者鼻咽咀嚼肌间隙内各结构的MRI表现;比较不同断面、序列对上颌动脉及下颌神经的显示情况。结果40例80侧鼻咽咀嚼肌间隙内肌肉及脂肪在T1WI及T2WI上均能较好显示;经统计学分析,冠状面T1WI及横断面梯度回波序列图像对鼻咽咀嚼肌间隙内上颌动脉主干的显示优于横断面T1WI及T2WI、冠状面T2WI及梯度回波序列图像;冠状面T1WI图像对下颌神经的显示优于冠状面T2WI及梯度回波序列图像。结论MRI能够显示鼻咽咀嚼肌间隙内肌肉、脂肪、上颌动脉主干、脑膜中动脉及下颌神经在鼻咽咀嚼肌间隙内的大体走行。     

Threshold‐automated CT measurements of muscle size and radiological attenuation in multiple lower‐extremity muscles of older individuals

Muscle atrophy and fat infiltration, two indicators of deconditioning and weakness in elderly frail patients, are typically assessed by means of manual image analysis from computed tomography (CT) scans. As this time‐consuming image analysis limits its wider use in clinical studies, the use of tissue thresholds to semi‐automatically assess muscle composition has been suggested. Here, we aimed to investigate the relationship between manual and semi‐automated analysis of both cross‐sectional area (CSA) and radiological attenuation (RA), in multiple muscles of the lower extremities in aged (77 ± 6 years) sedentary individuals (n = 40). The participants underwent CT scans of their lower limbs, including hip, thigh and calf muscles. The subsequent analysis of CSA and RA was conducted using both manual segmentation and semi‐automatic thresholds (?30 to +150 Hounsfield units). Automated measurements were generally strongly correlated with manually encircled CSA in all muscle groups (R = 0.79–0.99, p < .05) and shortened the analysis time by 70% (p < .05). In m. iliopsoas, however, the CSA became overestimated (15%, p < .05) with thresholded measurements, while the assessment of both CSA and RA was underestimated in muscles with high‐fat content (i.e., the gluteal muscles) and in individuals with high‐fat infiltration. In conclusion, using the semi‐automated technique with conventional thresholds is a time‐saving method that delivers accurate gross size of the muscle groups, particularly in the thigh. However, caution should be exercised when using semi‐automated techniques for assessing CSA and fat infiltration in muscles with high‐fat content.     

Development of an ultra-broadband ultrasonic imaging system: prototype mechanical sector device

Purpose We constructed an ultra-broadband ultrasonic transducer in a mechanical sector device, and prototyped a system to generate real-time images with higher harmonics. The potential of the system to reduce speckle was also studied. Methods To efficiently detect the higher harmonic components in echo signals, in addition to the transmitting transducer, another transducer only for broadband reception is necessary. We constructed a receiving transducer by bonding a polyvinylidene fluoride (PVDF) high-polymer piezofilm to the radiation surface of the transmitting lead zirconate titanate (PZT) transducer. By building this PZT-PVDF bi-layered ultrasonic probe into a mechanical sector scanner of an ultrasonic diagnosis system, an ultra-broadband ultrasonic imaging system capable of real-time imaging was prototyped. Results Using images of phantoms in water acquired using the prototype system, the acquisition of higher harmonic images with less noise up to the fourth order was demonstrated. In addition, we confirmed that the logarithmic summation of harmonic components from the fundamental to the fourth harmonic effectively reduces speckle noise in the images. Conclusions By obtaining an echo signal from phantoms using a PZT-PVDF bi-layered ultrasonic mechanical sector probe, real-time imaging was carried out, and the effectiveness of its higher harmonic components from the fundamental to the fourth harmonic was confirmed with respect to speckle reduction.