Citations

Measurement of surface roughness irregularities is an important indicator of product quality for many nondestructive testing industries. Many techniques exist; however, because of their qualitative, time-consuming and direct-contact modes, it is of some importance to work out new experimental methods and efficient tools for quantitative estimation of surface roughness. Continuous-wave ultrasound reflectometry (CWUR) is presented here as a novel nondestructive modality for imaging and measuring surface roughness in a noncontact mode. In CWUR, voltage variations due to phase shifts in the reflected ultrasound waves are recorded and processed to form an image of surface roughness. An acrylic test block with surface irregularities ranging from 4.22 to 19.05 μm as measured by a coordinate measuring machine (CMM) is scanned by an ultrasound transducer having a diameter of 45 mm, a focal distance of 70 mm, and a central frequency of 3 MHz. It is shown that CWUR technique gives very good agreement with the results obtained through CMM inasmuch as the maximum average percent error is around 11.5%.

This study seeks to examine the effect of level of presentation on scaling of speech intelligibility of speakers with dysarthria. Previous data [Kim et al. (2007)] reported the somewhat surprising result that different presentation levels do not cause a significant change in speech intelligibility scores of speakers with dysarthria, but do for healthy speakers. The current study reports further data using the same speech stimuli, however, with a main focus on the across-conditions effect of presentation level, since the previous data were limited to within-conditions effects. Four conditions of level of presentation were generated by varying absolute level of presentation (high and low) and normalizing each utterance for peak vowel intensity (adjusted and nonadjusted). In this presentation, we will report how scaled speech intelligibility is affected by the level of presentation of speech samples produced by speakers with various types and severity of dysarthria and by healthy speakers. The results of this study will be helpful to understand the rationale of speech therapy for dysarthria, especially considering the frequent use of speech intelligibility and speech therapy techniques designed based on intensity variation of speech. [Work supported by NIH DC00319 and internal fund from Louisiana State University.]

Diastolic dysfunction is the impaired ability of the left ventricle (LV) to passively fill during diastole and maintain its stroke volume at physiologic filling pressures and is associated with impaired relaxation and reduced compliance of LV. Knowledge of the quantitative values of the myocardial viscoelastic properties would improve the clinician’s ability to evaluate diastolic dysfunction in patients. To gain better understanding of the viscoelastic properties of the LV as a function of geometry, we studied Lamb wave propagation in different directions in excised porcine free-wall myocardium. The phantom consisting of a dissected porcine LV free-wall embedded in gelatin was fixed in a water tank. A mechanical shaker was used for harmonic excitation over a range of 40–500 Hz and a 7.5 MHz ultrasound transducer was used for motion measurements. Motion amplitude and phase at different depths of the sample were analyzed to obtain dispersion curves in four orthogonal directions. The data were fitted to the Lamb wave equations and shear elasticity and viscosity coefficients were estimated. The values of μ1 and μ2 were 13.75 ± 0.96 and 5.86 ± 0.75 Pa s. Our results suggest that the viscoelastic characteristics of the porcine LV free-wall in orthogonal directions were similar.

The objective of this study was to assess the potential for noninvasively identifying viscoelastic material properties in arterial vessels using ultrasound radiation force and modern computational inverse problem techniques. A rubber tube embedded in gelatin was excited at different points along the axis using impulsive ultrasound radiation force. The resulting mechanical waves were measured using a laser vibrometer and pulse-echo ultrasound. The inverse problem was cast as an optimization problem, in which the discrepancy between the measured dynamic response and the computed finite element model response was minimized with respect to viscoelastic material parameters. The model was very sensitive to the tube’s viscoelastic parameters and relatively insensitive to those of the gelatin. The viscoelastic properties of the tube obtained from the inverse problem were compared to the results obtained from a dynamic mechanical analyzer (DMA). For the overlapping range of frequencies (130–190 Hz), the results of the inverse problem gave an equivalent modulus that range from 7.3–8.5 MPa, while the DMA values range from 6.0–9.2 MPa. These results have important implications for using ultrasound radiation force in noninvasive characterization of the viscoelastic properties of arteries in vivo. [This work was supported in part by Grant No. EB002640 from NIH.]

AbstractPurposeDistance from health care facilities can be a barrier to colorectal cancer (CRC) screening, especially for colonoscopy. Alternatively, an improved at‐home stool‐based screening tool, the fecal immunochemical test (FIT), requires only a single sample and has a better sensitivity‐specificity balance compared to traditional guaiac fecal occult blood tests. Our objective was to determine if FITs mailed to asymptomatic, average‐risk patients overdue for screening resulted in higher screening rates versus mailing educational materials alone or no intervention (ie, usual care).MethodsVeterans ages 51‐64, asymptomatic, at average risk for CRC, overdue for screening and in a veterans administration (VA) catchment area covering a large rural population were randomly assigned to 3 groups: (1) education only (Ed) group: mailed CRC educational materials and a survey of screening history and preferences (N = 499); (2) FIT group: mailed the FIT, plus educational materials and survey (N = 500); and (3) usual care (UC) group: received no mailings (N = 500).FindingsAt 6 months postintervention, 21% of the FIT group had received CRC screening by any method compared to 6% of the Ed group (and 6% of the UC group) (P < .0001). Of the 105 respondents from the FIT group, 71 (68%) were eligible to take the FIT. Of those, 64 (90%) completed the FIT and 8 (12%) tested positive.ConclusionsThis low‐intensity intervention of mailing FITs to average risk patients overdue for screening resulted in a significantly higher screening rate than educational materials alone or usual care, and may be of particular interest in rural areas.

We report the finding of Iodamoeba butschlii amebic cysts on a liquid‐based anal Pap smear from an HIV‐positive male. Iodine staining of the smear confirmed the diagnosis. It is important to distinguish I. butschlii from pathogenic ameobae and other organisms seen on anal Pap smears. Diagn. Cytopathol 2014;42:775–777. © 2013 Wiley Periodicals, Inc.

The detrimental effect of speaker variability on word recognition has been reported using a wide variety of tasks and stimuli. In this study, the use of dysarthric speech alongside unimpaired speech allowed us to examine the effect of indexical variability from a new perspective. We compared voice-specificity effects in words produced by healthy speakers and the same words produced by dysarthric patients suffering from Huntington’s disease (HD). The speech of persons with HD is particularly suited to this issue because of its idiosyncratic and variable manifestation. Reaction time and accuracy results provided confirmatory evidence for Luce et al.’s (2003) time-course hypothesis: The slower responses occasioned by processing dysarthric stimuli were accompanied with greater reliance on surface details of the stimuli. Thus, specificity effects can be seen as resulting from a coping strategy called upon when the system is presented with an input that is highly dissimilar from canonical lexical representations. In addition, we found some evidence that the time-course hypothesis holds even when intelligibility is controlled. This finding confirms that time, rather than processing effort, is the cause of specificity effects, with activation confined to abstract representations in an early stage and spreading to episodic traces later on.

Disturbances in speech rhythm are common in dysarthria, and deficit patterns vary among dysarthria subtypes. Attempts to quantify differences in disordered rhythm patterns have met with limited success. Here, we attempt to differentiate various forms of dysarthria using metrics designed to quantify linguistic rhythm on a stress-timed versus syllable-timed continuum. Speakers with hypokinetic, ataxic, hyperkinetic, or mixed flaccid-spastic dysarthria read sentences. Rhythm metrics were calculated for these utterances based on vocalic and consonantal interval durations. Differences among groups were discovered for %V (percentage of utterance duration comprised of vocalic intervals), VarcoV (rate-normalized standard deviation of vocalic interval durations), and nPVI-V (normalized pairwise variability index for vocalic intervals). Differences were independent of variable speaking rates among groups. All dysarthric groups produced rhythm patterns less stress-timed than the control American English speakers, with lower VarcoV and nPVI-V and higher %V. Those with flaccid-spastic dysarthria secondary to amyotrophic lateral sclerosis exhibited a syllable-timed pattern more extreme than even control Spanish speakers, indicating minimal differentiation of stressed and unstressed syllables. These results show that the various types of rhythmic disturbance accompanying dysarthria can be effectively described and distinguished within a stress-/syllable-timed continuum and relative to healthy speech.

The mechanical response of tissues to external forces has gained considerable interest in medical diagnosis. One approach of imaging the tissue elastic properties is to apply an external force on the surface of the body. Another approach is to generate a localized force inside the tissue with the radiation force of ultrasound. In this paper, a noninvasive method for imaging the vibration mode of an object is investigated. The radiation force of ultrasound is used to scan the object at a resonant frequency of the object. The vibration of the object is measured by laser and the resulting acoustic emission from the object is measured by a hydrophone. Experimental studies are carried out on a mechanical heart valve and arterial phantoms. The mode images on the valve are made by the hydrophone measurement and confirmed by FEM simulations. Compared with conventional B-scan imaging on arterial phantoms, the mode imaging can show not only the interface of the artery and the gelatin, but also the vibration modes of the artery. The images taken on the phantom surface suggest that an image of an interior artery can be made by vibration measurements on the surface of the body.