MR Elastography of the Breast: Evolution of Technique,Case Examples,and Future Directions

Recognizing that breast cancers present as firm, stiff lesions, the foundation of breast magnetic resonance elastography (MRE) is to combine tissue stiffness parameters with sensitive breast MR contrast-enhanced imaging. Breast MRE is a non-ionizing, cross-sectional MR imaging technique that provides for quantitative viscoelastic properties, including tissue stiffness, elasticity, and viscosity, of breast tissues. Currently, the technique continues to evolve as research surrounding the use of MRE in breast tissue is still developing. In the setting of a newly diagnosed cancer, associated desmoplasia, stiffening of the surrounding stroma, and necrosis are known to be prognostic factors that can add diagnostic information to patient treatment algorithms. In fact, mechanical properties of the tissue might also influence breast cancer risk. For these reasons, exploration of breast MRE has great clinical value. In this review, we will: (1) address the evolution of the various MRE techniques; (2) provide a brief overview of the current clinical studies in breast MRE with interspersed case examples; and (3) suggest directions for future research.     

Oscillating Swelling–Shrinking Dynamics and Diffusive Properties of Weakly Cationic Poly(Aminoalkyl Methacrylate)‐Based Cryogels: Quantifying the Influence of Polymer Network Parameters

Thermodynamic properties of swelling equilibria and variability of dynamic response of pH‐sensitive polybases are examined. Poly(aminoalkyl methacrylate)‐based cryogels and hydrogels are prepared in a facile way by crosslinking polymerization of amine functional monomer N,N‐dimethylaminoethyl methacrylate (DMAEMA) in the presence of diethyleneglycol dimethacrylate as crosslinker at temperatures below and above freezing point of polymerization solvent, water, via cryogelation and conventional crosslinking polymerization. The effect of polymerization temperature on swelling characteristics of the prepared polybasic gels is investigated as a function of the gel‐preparation concentration. The overshooting effect is observed during pH‐dependent swelling of poly(N,N‐dimethylaminoethyl methacrylate) (PDMAEMA) hydrogels in acidic medium. Protonation/deprotonation of tertiary amine groups in network‐forming polymer demonstrates critical swelling behavior as pH of the swelling medium increases. Oscillating swelling–shrinking studies are performed and effective diffusion coefficient of water within PDMAEMA cryogel and hydrogel matrices is estimated using the dynamic swelling profiles. The mechanism of cyclic swelling–shrinking process of PDMAEMA cryogels and hydrogels are analyzed to control their pulsatile output patterns in metabolic oscillations. Considering the swelling process occurs through Fickian diffusion mechanism in acidic solutions, polybasic cryogels and hydrogels prepared in this study are thus proposed as good candidates for delivery applications.     

弹性成像与超声造影联合应用诊断甲状腺微小乳头状癌的价值

目的：探讨弹性成像（UE）与超声造影（CEUS）联合应用诊断甲状腺微小乳头状癌（PTMC）的价值。方法：对常规超声检测出确定性困难的73例80个甲状腺微小结节进行 UE 及 CEUS 检查,所有结节均经手术病理证实。结果：80个结节中 UE5分法诊断正确率为92．5％（74／80）,其中3例恶性结节误诊为良性结节,3例良性结节误诊为恶性。CEUS 诊断正确率为85．0％（68／80）,其中6例 PTMC 误诊为良性病变,6例良性结节误诊为 PTMC;UE 诊断甲状腺微小癌的敏感性94．0％,特异性90．0％,准确性92．5％;CEUS 诊断甲状腺微小癌的敏感性88．0％,特异性80．0％,准确性85．0％。联合应用 UE 和CEUS 诊断甲状腺微小癌的敏感性96．7％,特异性92．7％,准确性94．9％。结论：UE 和 CEUS 对于诊断 PTMC 方面均有较高的诊断价值,二者联合应用大于任意单项检查的诊断效能。     

Real time tissue elasticity imaging using the combined autocorrelation method

The elastic properties of tissues are expected to provide novel information for use in diagnosing pathologic changes in tissues and discriminating between malignant and benign tumors. Because it is hard to directly estimate the elastic modulus distribution from echo signals, methods for imaging the distribution of tissue strain under static compression are being widely investigated. Imaging the distribution of strain has proven to be useful for detecting disease tissues on the basis of their differences in elastic properties, although it is more qualitative than elastic modulus distribution. Many approaches to obtaining strain images from echo signals have been proposed. Most of these approaches use the spatial correlation technique, a method of detecting tissue displacement that provides maximum correlation between the echo signal obtained before and the one obtained after compression. Those methods are not suited for real-time processing, however, because of the amount of computation time they require. An alternative approach is a phase-tracking method, which is analogous to Doppler blood flowmetry. Although it can realize the rapid detection of displacement, the aliasing effect prevents its application to the large displacements that are necessary to improve the S/N ratio of the strain image. We therefore developed a more useful technique for imaging tissue elasticity. This approach, which we call the combined autocorrelation (CA) method, has the advantages of producing strain images of high quality with real-time processing and being applicable to large displacements. Numeric simulation and phantom experimentation have demonstrated that this method's capability to reconstruct images of tissue strain distribution under practical conditions is superior to that of the conventional spatial correlation method. In simulation and phantom experimentation, moreover, the image of elastic modulus distribution was also obtained by estimating stress distribution using a three-dimensional tissue model. When the proposed CA method was used to measure breast tumor specimens, the obtained strain images clearly revealed harder tumor lesions that were only vaguely resolved in B-mode images. Moreover, the results indicated the possibility of extracting the pathological characteristics of a tumor, making it useful for determining tumor type. These advantages justify the clinical use of the CA method.     

Evaluation of scar quality after treatment of superficial burns of the hands and face with Dressilk or Biobrane—An intra-individual comparison

Introduction

The aesthetic outcome after burn of exposed areas such as the hand and face is of high importance. A number of wound dressings used for the treatment of superficial and partial thickness burns promise rapid wound healing and reduced scarring. Previously, wound healing of hands and faces with superficial burns treated with Dressilk^® compared to Biobrane^® was evaluated intra-individually with similar results. Nevertheless, up to date objective information regarding the scarring after superficial burns treated with Dressilk^® does not exist.

氟伐他汀改善高血压患者脉压和动脉弹性临床研究

目的　观察氟伐他汀对降压治疗中高血压患者脉压和动脉弹性功能的影响。方法　选择 3 0例正在规律服用降压药物治疗并且脉压≥ 60mmHg的高血压患者 ,分为安慰剂组 (15例 )和氟伐他汀组 (15例 ) ,分别加服安慰剂 (1片每天 )或氟伐他汀 (40mg/d) ,治疗 3个月。观察治疗前、后肱动脉血压 ,脉搏波传导速度 (PWV) ,大动脉和小动脉弹性指数 (C1和C2 ) ,从桡动脉压力波形实时获得的中心动脉血压、压力反射波增强指数 (AI)。结果　安慰组治疗后各项指标均无显著改变。氟伐他汀组治疗后肱动脉收缩压与脉压分别降低 8 0± 12 9mmHg (P =0 0 3 1)与 5 7± 9 3mmHg (P =0 0 3 3 ) ,中心动脉收缩压与脉压分别降低 9 7± 12 4mmHg (P =0 0 0 9)与 7 1± 9 3mmHg (P =0 0 1) ,中心动脉下降幅度大于肱动脉 ;舒张压和心率无显著改变 ;C2 升高 (P =0 0 3 ) ;AI降低 (P =0 0 2 6) ;PWV和C1无显著改变。结论　氟伐他汀通过改善高血压患者小动脉弹性和外周压力波反射 ,具有缩小脉压的作用     

Shear wave elasticity imaging: a new ultrasonic technology of medical diagnostics

Shear wave elasticity imaging (SWEI) is a new approach to imaging and characterizing tissue structures based on the use of shear acoustic waves remotely induced by the radiation force of a focused ultrasonic beam. SWEI provides the physician with a virtual “finger” to probe the elasticity of the internal regions of the body. In SWEI, compared to other approaches in elasticity imaging, the induced strain in the tissue can be highly localized, because the remotely induced shear waves are attenuated fully within a very limited area of tissue in the vicinity of the focal point of a focused ultrasound beam. SWEI may add a new quality to conventional ultrasonic imaging or magnetic resonance imaging. Adding shear elasticity data (“palpation information”) by superimposing color-coded elasticity data over ultrasonic or magnetic resonance images may enable better differentiation of tissues and further enhance diagnosis. This article presents a physical and mathematical basis of SWEI with some experimental results of pilot studies proving feasibility of this new ultrasonic technology. A theoretical model of shear oscillations in soft biological tissue remotely induced by the radiation force of focused ultrasound is described. Experimental studies based on optical and magnetic resonance imaging detection of these shear waves are presented. Recorded spatial and temporal profiles of propagating shear waves fully confirm the results of mathematical modeling. Finally, the safety of the SWEI method is discussed, and it is shown that typical ultrasonic exposure of SWEI is significantly below the threshold of damaging effects of focused ultrasound.     

Myocardial elasticity and left ventricular distensibility as related to oxygen deficiency and right ventricular filling. Analysis in a rat heart model

Summary Hypoxia-induced changes in diastolic left ventricular (LV) pressure volume (P-V) relationships and myocardial elasticity as well as the extent to which diastolic right ventricular (RV) interactions are involved under hypoxia were analysed in male open-chest Wistar rats under isovolumetric conditions. Wall stress and differential elastic modulus E were calculated for the midwall region, assuming a spherical model.LV end-diastolic P-V relationship shifted significantly to the left only 2 min after the start of pure N₂ ventilation. The slope of the E- curve did not change, corresponding to the contracture type of decreased myocardial distensibility. Identical changes occurred when filling of the RV was increased under O₂ ventilation. Hypoxia, under emptied RV, led within 8 min to substantially lower, nonsignificant steepening of the end-disastolic P-V relationships. There was a significant change in the diastolic P-V curve along with a parallel increase in stiffness constant b, 45 min after N₂ ventilation and under emptied RV. However, as a result of failure of cardiac function, ischemia was by now prevailing.These findings led to the following conclusions: In the early phase of hypoxia, i. e. within the first 20 min (in the model used in the present study) no substantial rigor occurs but the increase of LV end-diastolic P-V values is essentially due to augmented RV filling, even under opened chest and removed pericardium. The geometrical influence of the RV mimics the contracture type of decreased myocardial distensibility and cannot be recognized on the basis of the E- relationship. Without knowledge of RV pressure it is not feasible to distinguish early contracture or rigor from extraventricular influences, caused by changes in the filling of the neighbouring ventricle.Presented in part at the Symposium Aktuelle Probleme der Herzdynamik (1984) supported by Fritz Thyssen Stiftung and at the Symposium of the Working Group on Valvular Prostheses, Ermatingen, Switzerland (1984)     

各种降压药对原发性高血压患者动脉弹性功能的影响

目的评价不同类型降压药对原发性高血压患者大小动脉弹性功能的影响。方法 105例1～2级原发性高血压患者,随机分为5组:氢氯噻嗪组(12.5 mg 1次/d,n=18)、比索洛尔组(5 mg 1次/d,n=20)、氨氯地平组(5 mg 1次/d,n=24)、苯那普利组(10 mg 1次/d,n=22)、缬沙坦组(80 mg 1次/d,n=21)。治疗4周后,如血压仍>140/90 mmHg,剂量加倍,疗程共12周。治疗前后观察大、小动脉弹性指数(C_1,C_2)及肱踝脉搏波传导速度(baPWV)。结果1)治疗12周后各组血压均有显著的降低,但各组间的血压变化无显著差别。比索洛尔组治疗后心率明显减慢[治疗后(66±4)比治疗前(74±7)次/mm,P<0.05]。2)调整血压降低幅度及 C_1、C_2、baPWV 基础值后,氨氯地平、苯那普利、缬沙坦对 C_1、C_2、baPWV 仍有显著性改善作用,比索洛尔及氢氯噻嗪对 C_1、C_2、baPWV则无显著性改善作用。3)baPWV 变化百分比与 DBP 下降幅度呈正相关(r=0.314,P<0.05),与 SBP 下降幅度无关(r=0.108,P>0.05)。结...