Mechanical Imaging - a Technology for 3-D Visualization and Characterization of Soft Tissue Abnormalities. A Review.
Authors: Sarvazyan A, Egorov V
Abstract
Mechanical Imaging (MI) is a branch of Elastography. MI differs from conventional ultrasonic and MR elastography in that it evaluates soft tissue mechanical structure using stress data rather than dynamic or static strain data. MI closely mimics manual palpation because the MI probe with a force sensor array attached to its tip acts as a palpating finger. MI is intrinsically a three-dimensional imaging modality because the surface stress patterns obtained at different levels of tissue compression are defined by three-dimensional mechanical structure of the tissue. Th...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
An overview of elastography - an emerging branch of medical imaging.
We present a classification of elasticity measurement and imaging techniques based on the methods used for generating a stress in the tissue (external mechanical force, internal ultrasound radiation force, or an internal endogenous force), and measurement of the tissue response. The measurement method can be performed using differing physical principles including magnetic resonance imaging (MRI), ultrasound imaging, X-ray imaging, optical and acoustic signals.Until recently, EI was largely a research method used by a few select institutions having the special equipment needed to perform the studies. Since 2005 however, inc...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
A Review of Vibro-acoustography and its Applications in Medicine.
Authors: Urban MW, Alizad A, Aquino W, Greenleaf JF, Fatemi M
Abstract
In recent years, several new techniques based on the radiation force of ultrasound have been developed. Vibro-acoustography is a speckle-free ultrasound based imaging modality that can visualize normal and abnormal soft tissue through mapping the acoustic response of the object to a harmonic radiation force induced by ultrasound. In vibro-acoustography, the ultrasound energy is converted from high ultrasound frequencies to a low acoustic frequency (acoustic emission) that is often two orders of magnitude smaller than the ultrasound freq...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
Acoustic Radiation Force Impulse (ARFI) Imaging: a Review.
Authors: Nightingale K
Abstract
Acoustic radiation force based elasticity imaging methods are under investigation by many groups. These methods differ from traditional ultrasonic elasticity imaging methods in that they do not require compression of the transducer, and are thus expected to be less operator dependent. Methods have been developed that utilize impulsive (i.e. < 1 ms), harmonic (pulsed), and steady state radiation force excitations. The work discussed herein utilizes impulsive methods, for which two imaging approaches have been pursued: 1) monitoring the tissue response within the radiation ...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
Recent results in nonlinear strain and modulus imaging.
We report a summary of recent developments and current status of our team's efforts to image and quantify in vivo nonlinear strain and tissue mechanical properties. Our work is guided by a focus on applications to cancer diagnosis and treatment using clinical ultrasound imaging and quasi-static tissue deformations. We review our recent developments in displacement estimation from ultrasound image sequences. We discuss cross correlation approaches, regularized optimization approaches, guided search methods, multiscale methods, and hybrid methods. Current implementations can return results of high accuracy in both axial and ...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
A Review of Shearwave Dispersion Ultrasound Vibrometry (SDUV) and its Applications.
Authors: Urban MW, Chen S, Fatemi M
Abstract
Measurement of tissue elasticity has emerged as an important advance in medical imaging and tissue characterization. However, soft tissue is inherently a viscoelastic material. One way to characterize the viscoelastic material properties of a material is to measure shear wave propagation velocities within the material at different frequencies and use the dispersion of the velocities, or variation with frequency, to solve for the material properties. Shearwave Dispersion Ultrasound Vibrometry (SDUV) is an ultrasound-based technique that uses this feature to chara...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
MRI of Focal Liver Lesions.
Authors: Albiin N
Abstract
Magnetic resonance imaging, MRI has more advantages than ultrasound, computed tomography, CT, positron emission tomography, PET, or any other imaging modality in diagnosing focal hepatic masses. With a combination of basic T1 and T2 weighted sequences, diffusion weighted imaging, DWI, and hepatobiliary gadolinium contrast agents, that is gadobenate dimeglumine (Gd-BOPTA) and gadoxetic acid (Gd-EOB), most liver lesions can be adequately diagnosed. Benign lesions, as cyst, hemangioma, focal nodular hyperplasia, FNH or adenoma, can be distinguished from malignant lesions. In a non-c...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
Viewpoints on Medical Image Processing: From Science to Application.
Authors: Deserno Né Lehmann TM, Handels H, Maier-Hein Né Fritzsche KH, Mersmann S, Palm C, Tolxdorff T, Wagenknecht G, Wittenberg T
Abstract
Medical image processing provides core innovation for medical imaging. This paper is focused on recent developments from science to applications analyzing the past fifteen years of history of the proceedings of the German annual meeting on medical image processing (BVM). Furthermore, some members of the program committee present their personal points of views: (i) multi-modality for imaging and diagnosis, (ii) analysis of diffusion-weighted imaging, (iii) model-base...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
Acoustic Inversion in Optoacoustic Tomography: A Review.
Authors: Rosenthal A, Ntziachristos V, Razansky D
Abstract
Optoacoustic tomography enables volumetric imaging with optical contrast in biological tissue at depths beyond the optical mean free path by the use of optical excitation and acoustic detection. The hybrid nature of optoacoustic tomography gives rise to two distinct inverse problems: The optical inverse problem, related to the propagation of the excitation light in tissue, and the acoustic inverse problem, which deals with the propagation and detection of the generated acoustic waves. Since the two inverse problems have different physical underpinn...
Source: Current Medical Imaging Reviews - November 19, 2015 Category: Radiology Tags: Curr Med Imaging Rev Source Type: research
