Utilizing the "Experience Sampling Method" to Monitor Communicative Quality of Life During Treatment for a Single Subject with Chronic Aphasia

Research in chronic aphasia typically incorporates Quality of Life measures to determine functional outcomes of treatment. This single subject study utilizes the Experience Sampling Method (ESM) in which the 75 year old, one year post CVA subject responds to 4-5 questions on a Palm Tungsten Personal Data Assistant (PDA) at the end of each activity during an intensive treatment program. Comparison of responses to the 10 treatment activities suggests that responses regarding the perception of communication and stress were the most negative, but, that less structured activities were more stressful than those communicatively focused. Theoretical and clinical findings will be discussed

Diagnosing Cysts With Correlation Coefficient Images From 2‐Dimensional Freehand Elastography

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/135592/1/jum20072691201.pd

Competition between transients in the rate of approach to a fixed point

Dynamical systems studies of differential equations often focus on the behavior of solutions near critical points and on invariant manifolds, to elucidate the organization of the associated flow. In addition, effective methods, such as the use of Poincare maps and phase resetting curves, have been developed for the study of periodic orbits. However, the analysis of transient dynamics associated with solutions on their way to an attracting fixed point has not received much rigorous attention. This paper introduces methods for the study of such transient dynamics. In particular, we focus on the analysis of whether one component of a solution to a system of differential equations can overtake the corresponding component of a reference solution, given that both solutions approach the same stable node. We call this phenomenon tolerance, which derives from a certain biological effect. Here, we establish certain general conditions, based on the initial conditions associated with the two solutions and the properties of the vector field, that guarantee that tolerance does or does not occur in two-dimensional systems. We illustrate these conditions in particular examples, and we derive and demonstrate additional techniques that can be used on a case by case basis to check for tolerance. Finally, we give a full rigorous analysis of tolerance in two-dimensional linear systems.Comment: Resolution on the figures of the paper has been reduced to conserve file space. Animation files are viewable at: http://people.mbi.ohio-state.edu/jday/Tol_Animations.htm

Anisotropic ultrasonic backscatter from the renal cortex

We have demonstrated a significant, directionally dependent, anisotropic, echogenicity from the cortices of two sheep kidneys and a normal human cadaver kidney. The anisotropy corresponds to the relationship of the sound field to the medullary rays and interlobular arteries. At 7.5 MHz, the backscatter from specimens of cortex of a sheep kidney was 4.7 +/- .7 dB (mean +/- SEM) greater in parts of the cortex where the field was perpendicular to these structures as opposed to where it was parallel to them. In addition, we measured the angular distribution of this anisotropy and compared it to the 5 dB inclusion angle of the 5 MHz linear array that was used in measurements on the whole kidney specimens. The transducer inclusion angle was 10[deg] +/- 2[deg], while the angular distribution was 34[deg] +/- 22[deg] and 23[deg] +/- 11[deg] (mean +/- SD) for the intact sheep and human kidney, respectively, demonstrating some variation of the medullary rays from perfect specular reflectors. This anisotropy should be visible in standard diagnostic scanning, and its recognition could increase ultrasound's sensitivity for the detection of renal disease.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27571/1/0000615.pd

Constant soft tissue distance model in pregnancy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28106/1/0000554.pd

Determination of scan-plane motion using speckle decorrelation: Theoretical considerations and initial test

The correlation function of the echo signal intensities at a fixed region on a series of B-mode images is directly related to the change of speckle patterns between these images. An indication is given here of how the rate of the change of that correlation function can be used to estimate the scan-plane motion in any direction relative to the imaged tissue or other material. In this first implementation it is assumed that the statistical properties of the echo signals follow those of a complex circular Gaussian, and the case is considered of diffusely scattering tissue with many fine particles per resolution cell and with no phase distortion. The method is applied to data from a one-dimensional linear array and initial results are presented for scanning a tissue-mimicking phantom in the elevational direction of the transducer. Experimental results are in good agreement with the predictions. The current method should provide a good indication of the local rate of scan-head motion in those tissues in which the normalized correlation function of the echo signal intensities behaves, or can be made to behave, as it would for a medium with uniform acoustic properties and containing many, randomly distributed, pointlike scatterers, although application might be made to other situations where a deterministic condition exists for the correlation between images taken at differing locations within a volume. © 1997 John Wiley & Sons, Inc. Int J Imaging Syst Technol, 8, 38–44, 1997Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/35064/1/5_ftp.pd

Phase cancellation: A cause of acoustical shadowing at the edges of curved surfaces in B-mode ultrasound images

Acoustical shadowing occurring at the edges of curved objects is one of the most frequently observed artifacts in ultrasound imaging. This artifact has been generally ascribed to refraction and reflection effects at the boundary between the curved object and the surrounding tissues. However, the shadowing that would be produced by pure refraction and reflection may not correspond in all circumstances to what is most often seen clinically, i.e., a sharp, discrete shadow projecting down from the edge. We used a tissue-mimicking contrast detail phantom, speed of sound (SOS) 1477 m/s, containing cylindrically shaped wells to investigate the origin of these shadows. Using solutions of relatively high SOS (20% ethylene glycol), approximately equivalent SOS (distilled water), and low SOS (70% isopropyl alcohol), the phantom was scanned with the scanhead face oriented perpendicular to and parallel to the central axes of the cylinders. Shadowing could be produced in both cases when there was a SOS difference between the contents of the cylinders and the phantom. When scanning perpendicular to the cylinders, refraction and reflection effects could have contributed to any shadowing produced, but when the scan planes were oriented parallel to the central axes of the cylinders, neither refraction nor reflection could be occurring to a significant degree. The shadowing produced in these circumstances could be better explained by a phenomenon well known in transmission ultrasonography called phase cancellation. Phase cancellation would produce shadowing independent of scan plane orientation, and could contribute to the shadowing generated in clinical imaging.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29542/1/0000630.pd

Doppler ultrasound color flow imaging in the study of breast cancer: Preliminary findings

A prospective study of the Doppler color flow features of 55 proved breast cancers was performed. On a three-level scale of low to marked vascularity, visual assessment of the color flow images classified 82% of the cancers as moderately or markedly vascular (minimal: 14%, moderate: 29%, marked: 53%). Four percent of the cancers had no detectable flow. In 29 women, a volume of tissue comparable to the cancer was scanned in the contralateral normal breast. Sixty-nine percent of the normal breasts had moderate or marked vascularity (minimal: 28%, moderate: 41%, marked: 28%), and 3% were avascular. There was poor distinction between normal tissues and cancer which suggests that more sensitive Doppler methods than were employed in this study may be needed in order to detect the small vessel flow reported to be rather specific for malignancy. The high, 82%, detection rate of tumor vessels in this study suggests the potential use of color flow Doppler for directing more specific but lengthy Doppler procedures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28897/1/0000734.pd