Visualizing the mechanical wave of vocal fold tissue during phonation using electroglottogram-triggered ultrasonography.

In order to investigate the vibration pattern, especially the vibrational phase of tissue beneath the vocal fold mucosa, an imaging method called electroglottogram-triggered ultrasonography is proposed. The ultrasonic images of the vocal fold vibration are obtained in the coronal plane from five adult subjects during phonation. The velocity of the vocal fold tissue beneath the mucosal surface is obtained by using a motion estimation method. The results show that the vibration phase difference between tissues at different locations beneath the vocal fold mucosa results in a mechanical wave traveling upward at a speed of 720 to 1826 mm/s.

Visualizing the movement of the contact between vocal folds during vibration by using array-based transmission ultrasonic glottography.

For the purpose of noninvasively visualizing the dynamics of the contact between vibrating vocal fold medial surfaces, an ultrasonic imaging method which is referred to as array-based transmission ultrasonic glottography is proposed. An array of ultrasound transducers is used to detect the ultrasound wave transmitted from one side of the vocal folds to the other side through the small-sized contact between the vocal folds. A passive acoustic mapping method is employed to visualize and locate the contact. The results of the investigation using tissue-mimicking phantoms indicate that it is feasible to use the proposed method to visualize and locate the contact between soft tissues. Furthermore, the proposed method was used for investigating the movement of the contact between the vibrating vocal folds of excised canine larynges. The results indicate that the vertical movement of the contact can be visualized as a vertical movement of a high-intensity stripe in a series of images obtained by using the proposed method. Moreover, a visualization and analysis method, which is referred to as array-based ultrasonic kymography, is presented. The velocity of the vertical movement of the contact, which is estimated from the array-based ultrasonic kymogram, could reach 0.8 m/s during the vocal fold vibration.

Wavelet-transform-based active imaging of cavitation bubbles in tissues induced by high intensity focused ultrasound.

Cavitation detection and imaging are essential for monitoring high-intensity focused ultrasound (HIFU) therapies. In this paper, an active cavitation imaging method based on wavelet transform is proposed to enhance the contrast between the cavitation bubbles and surrounding tissues. The Yang-Church model, which is a combination of the Keller-Miksis equation with the Kelvin-Voigt equation for the pulsations of gas bubbles in simple linear viscoelastic solids, is utilized to construct the bubble wavelet. Experiments with porcine muscles demonstrate that image quality is associated with the initial radius of the bubble wavelet and the scale. Moreover, the Yang-Church model achieves a somewhat better performance compared with the Rayleigh-Plesset-Noltingk-Neppiras-Poritsky model. Furthermore, the pulse inversion (PI) technique is combined with bubble wavelet transform to achieve further improvement. The cavitation-to-tissue ratio (CTR) of the best tissue bubble wavelet transform (TBWT) mode image is improved by 5.1 dB compared with that of the B-mode image, while the CTR of the best PI-based TBWT mode image is improved by 7.9 dB compared with that of the PI-based B-mode image. This work will be useful for better monitoring of cavitation in HIFU-induced therapies.

Spatial-temporal ultrasound imaging of residual cavitation bubbles around a fluid-tissue interface in histotripsy.

Cavitation is considered as the primary mechanism of soft tissue fragmentation (histotripsy) by pulsed high-intensity focused ultrasound. The residual cavitation bubbles have a dual influence on the histotripsy pulses: these serve as nuclei for easy generation of new cavitation, and act as strong scatterers causing energy "shadowing." To monitor the residual cavitation bubbles in histotripsy, an ultrafast active cavitation imaging method with relatively high signal-to-noise ratio and good spatial-temporal resolution was proposed in this paper, which combined plane wave transmission, minimum variance beamforming, and coherence factor weighting. The spatial-temporal evolutions of residual cavitation bubbles around a fluid-tissue interface in histotripsy under pulse duration (PD) of 10-40 µs and pulse repetition frequency (PRF) of 0.67-2 kHz were monitored by this method. The integrated bubble area curves inside the tissue interface were acquired from the bubble image sequence, and the formation process of histotripsy damage was estimated. It was observed that the histotripsy efficiency decreased with both longer PDs and higher PRFs. A direct relationship with a coefficient of 1.0365 between histotripsy lesion area and inner residual bubble area was found. These results can assist in monitoring and optimization of the histotripsy treatment further.

Ultrafast active cavitation imaging with enhanced cavitation to tissue ratio based on wavelet transform and pulse inversion.

The quality of ultrafast active cavitation imaging (UACI) using plane wave transmission is hindered by low transmission pressure, which is necessary to prevent bubble destruction. In this study, a UACI method that combined wavelet transform with pulse inversion (PI) was proposed to enhance the contrast between the cavitation bubbles and surrounding tissues. The main challenge in using wavelet transform is the selection of the optimum mother wavelet. A mother wavelet named "cavitation bubble wavelet" and constructed according to Rayleigh-Plesset-Noltingk-Neppiras-Poritsky model was expected to obtain a high correlation between the bubbles and beamformed echoes. The method was validated by in vitro experiments. Results showed that the image quality was associated with the initial radius of bubble and the scale. The signal-to-noise ratio (SNR) of the best optimum cavitation bubble wavelet transform (CBWT) mode image was improved by 3.2 dB compared with that of the B-mode image in free-field experiments. The cavitation-to-tissue ratio of the best optimum PI-based CBWT mode image was improved by 2.3 dB compared with that of the PI-based B-mode image in tissue experiments. Furthermore, the SNR versus initial radius curve had the potential to estimate the size distribution of cavitation bubbles.

Enhanced lesion-to-bubble ratio on ultrasonic Nakagami imaging for monitoring of high-intensity focused ultrasound.

OBJECTIVES: This work explored the feasibility of using ultrasonic Nakagami imaging to enhance the contrast between thermal lesions and bubbles induced by high-intensity focused ultrasound (US) in a transparent tissue-mimicking phantom at different acoustic power levels. METHODS: The term "lesion-to-bubble ratio" was proposed and defined as the ratio of the scattered power from the thermal lesion to the scattered power from the bubbles calculated in the various monitoring of images for high-intensity focused US. Two-dimensional radiofrequency data backscattered from the exposed region were captured by a modified diagnostic US scanner to estimate the Nakagami statistical parameter, m, and reconstruct the ultrasonic B-mode images and Nakagami parameter images. The dynamic changes in the lesion-to-bubble ratio over the US exposure procedure were calculated simultaneously and compared among video photos, B-mode images, and Nakagami images for monitoring of high-intensity focused US. RESULTS: After a small thermal lesion was induced by high-intensity focused US in the phantom, the lesion-to-bubble ratio values corresponding to the video photo, B-mode image, and Nakagami image were 5.3, 1, and 9.8 dB, respectively. When a large thermal lesion appeared in the phantom, the ratio values increased to 7.2, 3, and 14 dB. During US exposure, the ratio values calculated for the video photo, B-mode image, and Nakagami image began to increase gradually and rose to peak values of 8.3, 2.9, and 14.8 dB at the end of the US exposure. CONCLUSIONS: This preliminary study on a tissue-mimicking phantom suggests that Nakagami imaging may have a potential use in enhancing the lesion-to-bubble ratio for monitoring high-intensity focused US. Further studies in vivo and in vitro will be needed to evaluate the potential applications for high-intensity focused US.

Measurement of the sound transmission characteristics of normal neck tissue using a reflectionless uniform tube.

Understanding the sound transmission of the neck tissue is necessary and important in areas such as vocal function evaluation and electrolarynx improvement. In this paper, a simple method using a reflectionless tube was proposed to measure the neck frequency response function (NFRF) of ten normal subjects (five males and five females) during Mandarin vowel production. The NFRFs across different subjects producing different vowels were measured at different neck positions and compared to confirm the effectiveness of the method, and determine the NFRF variations in normal subjects. The results showed that the proposed method offered an easy and effective way to obtain an accurate NFRF. For normal subjects, the neck tissue can be treated as a low-pass filter, with a maximum gain at 310 Hz and a roll-off at a slope of -8.4 dB/octave, flattening out above 2000 Hz. The measurement position on the neck did not influence the shape of the NFRF, but did change the overall gains of the NFRF. In addition, there was a significant gender difference in NFRFs at the low frequencies. Finally, some potential applications of this method and the results are suggested.

Measuring body layer vibration of vocal folds by high-frame-rate ultrasound synchronized with a modified electroglottograph.

The body-cover concept suggests that the vibration of body layer is an indispensable component of vocal fold vibration. To quantify this vibration, a synchronized system composed of a high-frame-rate ultrasound and a modified electroglottograph (EGG) was employed in this paper to simultaneously image the body layer vibration and record the vocal fold vibration phase information during natural phonations. After data acquisition, the displacements of in vivo body layer vibrations were measured from the ultrasonic radio frequency data, and the temporal reconstruction method was used to enhance the measurement accuracy. Results showed that the modified EGG, the waveform and characteristic points of which were identical to the conventional EGG, resolved the position conflict between the ultrasound transducer and EGG electrodes. The location and range of the vibrating body layer in the estimated displacement image were more clear and discernible than in the ultrasonic B-mode image. Quantitative analysis for vibration features of the body layer demonstrated that the body layer moved as a unit in the superior-inferior direction during the phonation of normal chest registers.

Surface vibration and nearby cavitation of an ex vivo bovine femur exposed to high intensity focused ultrasound.

The acoustic pressure distribution, thermal ablation, and sonochemiluminescence (SCL) generated by cavitation near the surface of an ex vivo bovine femur were investigated at normal and oblique incidences of high intensity focused ultrasound (HIFU), as were the characteristics of bone surface vibrations. The acoustic pressure at the HIFU focus, the width of thermal ablation, and the SCL intensity in the pre-focal region were 1.3 MPa, 7 mm, and 454 electrons, respectively, in the control group at normal incidence, and they respectively increased to 1.5 MPa, 12 mm and 968 electrons in the presence of the bone. At oblique incidence from the left, the acoustic pressure at 3 mm to the right of the HIFU focus was 0.6 MPa and decreased to 0.4 MPa at 3 mm to the left of the focus. The thermal ablation was 20 mm in width and extended along the front surface of the bone to the right of the HIFU focus. The SCL intensity on the right of the HIFU focus was 394 electrons and was 362 electrons on the left. The presence of bone would directionally change the spatial distribution of acoustic pressure, thermal and cavitation effects for oblique incidence of HIFU.

The effect of entrance radii on intraglottal pressure distributions in the divergent glottis.

Modeling laryngeal aerodynamics requires specification of the glottal geometry. Changing the glottal exit radius alters the intraglottal pressure distributions in the converging glottis [Scherer et al., J. Acoust. Soc. Am. 110, 2267-2269 (2001)]. This study examined the effects of the glottal entrance radius on the intraglottal pressure distributions for divergent angles of 5°, 10°, 20°, 30°, and 40°. Glottal airflow and minimal glottal diameter were held constant at 73.2 cm(3)/s and 0.02 cm, respectively. The computational code FLUENT was used to obtain the pressure distributions. Results suggest that a smaller glottal entrance radius tends to (1) lower the transglottal pressure (reduce glottal flow resistance), although this is angle dependent, (2) make the pressure dip near the glottal entrance more negative in value, (3) increase the slope of the pressure distribution just upstream of the glottal entrance, and (4) make the initial pressure recovery (rise) in the glottis steeper. A general empirical equation for transglottal pressure as a function of radius, angle, and separation point location is offered. These results suggest that glottal entrance curvature for the divergent glottis significantly affects the driving pressures on the vocal folds, and needs to be well specified when building computational and physical models.

Feasibility of using Nakagami distribution in evaluating the formation of ultrasound-induced thermal lesions.

The acoustic posterior shadowing effects of bubbles influence the accuracy for defining the location and range of ablated thermal lesions during focused ultrasound surgery when using ultrasonic monitoring imaging. This paper explored the feasibility of using Nakagami distribution to evaluate the ablated region induced by focused ultrasound exposures at different acoustic power levels in transparent tissue-mimicking phantoms. The mean value of the Nakagami parameter m was about 0.5 in the cavitation region and increased to around 1 in the ablated region. Nakagami images were not subject to significant shadowing effects of bubbles. Ultrasound-induced thermal lesions observed in the photos and Nakagami images were overshadowed by bubbles in the B-mode images. The lesion size predicted in the Nakagami images was smaller than that predicted in the photos due to the sub resolvable effect of Nakagami imaging at the interface. This preliminary study on tissue-mimicking phantom suggested that the Nakagami parameter m may have the potential use in evaluating the formation of ultrasound-induced thermal lesion when the shadowing effect of bubbles is strong while the thermal lesion was small. Further studies in vivo and in vitro will be needed to evaluate the potential application.

Compare ultrasound-mediated heating and cavitation between flowing polymer- and lipid-shelled microbubbles during focused ultrasound exposures.

This paper compares the efficiency of flowing polymer- and lipid-shelled microbubbles (MBs) in the heating and cavitation during focused ultrasound exposures. Temperature and cavitation activity were simultaneously measured as the two types of shelled MBs and saline flowing through a 3 mm diameter vessel in the phantom with varying flow velocities (0-20 cm/s) at different acoustic power levels (0.6-20 W) with each exposure for 5 s. Temperature and cavitation for the lipid-shelled MBs were higher than those for the polymer-shelled MBs. Temperature rise decreased with increasing flow velocities for the two types of shelled MBs and saline at acoustic power 1.5 W. At acoustic power 11.1 W, temperature rise increased with increasing flow velocities for the lipid-shelled MBs. For the polymer-shelled MBs, the temperature rise increased with increasing flow velocities from 3-15 cm/s and decreased at 20 cm/s. Cavitation increased with increasing flow velocity for the two shelled MBs and there were no significant changes of cavitation with increasing flow velocities for saline. These results suggested that lipid-shelled MBs may have a greater efficiency than polymer-shelled MBs in heating and cavitation during focused ultrasound exposures.

Design and evaluation of an electrolarynx with tonal control function for Mandarin.

OBJECTIVE: To improve the speech quality of laryngectomized speakers of Mandarin, we designed an electrolarynx with tonal control function (tone-EL) by using the movement of a trackball. The performance of the tone-EL in producing Mandarin was evaluated. METHODS: The performance of tone-EL was evaluated via a listening experiment. The perceptual accuracies of monosyllabic words, different categories of phrases with different cues were measured and compared with that produced with a conventional EL. The acceptability of sentences was also measured. RESULTS: The perceptual accuracies of monosyllabic words and tones associated with the words produced with the tone-EL were significantly higher than those of monotonic EL speech. The perceptual accuracy of phrases was significantly higher than in monotonic EL speech when no categorical cue for listeners was provided, whereas they were at a close level when categorical information of the phrases was provided in advance. The acceptability of sentences was higher than that of monotonic EL speech. CONCLUSION: Using the tone-EL can produce Mandarin tones effectively and the quality of rehabilitated Mandarin is better than using a conventional-EL. To balance speech intelligibility and ease of use, a strategy -producing tonal speech when few informative cues are available to listeners is preferred.

Minimizing the thermal losses from perfusion during focused ultrasound exposures with flowing microbubbles.

This paper demonstrated the use of flowing microbubbles (MBs) to minimize thermal losses from perfusion during focused ultrasound exposures due to acoustic cavitation. Temperature and cavitation were simultaneously investigated as MBs flowing through a wall-less flow phantom with varying flow velocities (2-55 cm/s) and concentrations (0%-0.1%) when exposed at different acoustic power levels (5-120 W). The peak temperature at the end of ultrasonic exposures in the flow and in the outer of the vessel as well as the cavitation were higher than those pure controls measured at the same exposure parameters and flow velocities but without MBs. All the peak temperatures initially increased with increasing flow velocities of MBs, followed by a decrease of the peak temperatures with increasing flow velocities when the velocity was higher than the inflection velocity. Meanwhile, cavitation showed a trend of increases with increasing flow velocity. The inflection velocity and cavitation increased with increasing acoustic power and MBs concentration. Thermal lesion appeared around the vessel as MBs flow through the vessel, at which lesion was not observed originally without MBs. These results suggested that this may provide an effective way to minimize thermal losses from perfusion during focused ultrasound exposures.

Intraglottal Pressure: A Comparison Between Male and Female Larynxes.

Acoustic differences in the phonated sounds made by men and women are related to laryngeal and vocal tract structural differences. This model-based study explored how typical vocal fold differences between males and females affect intraglottal pressure distributions under conditions of different glottal angles and transglottal pressures, and thus how they may affect phonation. The computational code ANSYS Fluent 6.3 was used to obtain the pressure distributions and other aerodynamic parameters for laminar, incompressible flow. Typical values of the vocal fold length, the vertical glottal duct length, and the lateral vocal fold tissue depth were selected both for males and females under conditions of nine typical convergent/divergent glottal angles and three transglottal pressures. There was no coupling of the upstream or downstream vocal tracts, and also no vocal fold contact in these two-dimensional static glottal geometries. Results suggest that males tend to have greater intraglottal pressures for the convergent glottal shape that occurs during glottal opening, and the male glottis offers less flow resistance than the female glottis. These results suggest that the male vocal folds may vibrate more easily (ie, with lower transglottal pressure) but the tissue differences may nullify such an hypothesis. Also, the peak velocities in the glottis were dependent on the transglottal pressure driving the flow and the minimal glottal diameter, which were the same for both the male and female larynxes, rather than on the inferior-superior length of the glottis or the anterior-posterior glottal length. In addition, the tangential forces for larger glottal convergent angles was significantly greater in the female larynx. The entrance loss coefficients, however, were similar between the male and female larynxes, except for the uniform glottis for which the values were larger for the male larynx. The results suggest that the structural differences between male and female vocal folds should be well specified when building computational and physical models of the larynx.

Cavitation characteristics of flowing low and high boiling-point perfluorocarbon phase-shift nanodroplets during focused ultrasound exposures.

This work investigated and compared the dynamic cavitation characteristics between low and high boiling-point phase-shift nanodroplets (NDs) under physiologically relevant flow conditions during focused ultrasound (FUS) exposures at different peak rarefactional pressures. A passive cavitation detection (PCD) system was used to monitor cavitation activity during FUS exposure at various acoustic pressure levels. Root mean square (RMS) amplitudes of broadband noise, spectrograms of the passive cavitation detection signals, and normalized inertial cavitation dose (ICD) values were calculated. Cavitation activity of low-boiling-point perfluoropentane (PFP) NDs and high boiling-point perfluorohexane (PFH) NDs flowing at in vitro mean velocities of 0-15 cm/s were compared in a 4-mm diameter wall-less vessel in a transparent tissue-mimicking phantom. In the static state, both types of phase-shift NDs exhibit a sharp rise in cavitation intensity during initial FUS exposure. Under flow conditions, cavitation activity of the PFH NDs reached the steady state less rapidly compared to PFP NDs under the lower acoustic pressure (1.35 MPa); at the higher acoustic pressure (1.65 MPa), the RMS amplitude increased more sharply during the initial FUS exposure period. In particular, the RMS-time curves of the PFP NDs shifted upward as the mean flow velocity increased from 0 to 15 cm/s; the RMS amplitude of the PFH ND solution increased from 0 to 10 cm/s and decreased at 15 cm/s. Moreover, amplitudes of the echo signal for the low boiling-point PFP NDs were higher compared to the high boiling-point PFH NDs in the lower frequency range, whereas the inverse occurred in the higher frequency range. Both PFP and PFH NDs showed increased cavitation activity in the higher frequency under the flow condition compared to the static state, especially PFH NDs. At 1.65 MPa, normalized ICD values for PFH increased from 0.93 ± 0.03 to 0.96 ± 0.04 and from 0 to 10 cm/s, then decreased to 0.86 ± 0.05 at 15 cm/s. This work contributes to our further understanding of cavitation characteristics of phase-shift NDs under physiologically relevant flow conditions during FUS exposure. In addition, the results provide a reference for selecting suitable phase-shift NDs to enhance the efficiency of cavitation-mediated ultrasonic applications.

IR780 loaded perfluorohexane nanodroplets for efficient sonodynamic effect induced by short-pulsed focused ultrasound.

Inertial cavitation is crucial for the therapeutic effects of sonodynamic. Therefore, approaches that can induce highly efficient inertial cavitation should be of benefit for sonodynamic effect. Our previous study demonstrated that highly efficient inertial cavitation activity can be achieved through the combinatorial use of a short-pulsed focused ultrasound (SPFU) sequence and perfluorohexane (PFH) nanodroplets. Herein, we applied the SPFU sequence and PFH nanodroplets in sonodynamic. A hydrophobic sonosensitizer, IR780 iodine, was loaded inside denatured bovine serum albumin-shelled PFH (PFH@BSA-IR780) nanodroplets. The sonodynamic efficacy was validated by treating HeLa cervical cancer cells. Under SPFU exposure, PFH@BSA-IR780 nanodroplets were highly effective in promoting reactive oxygen species generation and inducing cancer cell death. A significant decrease in cell viability was achieved within just 10 s. Besides the cytotoxicity of ROS, the mechanical bioeffects of inertial cavitation also led to severe cell death resulting from higher acoustic power or the longer treatment time. The application of the SPFU sequence coupled with PFH@BSA-IR780 nanodroplets is a promising strategy for efficient sonodynamic.

The effects of the false vocal fold gaps on intralaryngeal pressure distributions and their effects on phonation.

Human phonation does not merely depend on the vibration of the vocal folds. Research by clinical and computer simulations has demonstrated that the false vocal fold (FVF) is an important laryngeal constriction that plays a vital role during human voice production. This study explored the effects of the FVF gaps using both the three-dimensional Plexiglas model and the numerical computation methods. Twelve FVF gaps (ranging from 0.02 to 2.06 cm) were used in this study at three glottal angles (uniform and convergent/divergent 40 degrees ), two minimal glottal diameters (D (g)) (0.04 cm and 0.06 cm) separately, and the constant subglottal pressure (8 cm H(2)O). The results suggested that (1) the intralaryngeal pressure was the lowest and the flow was the highest (least flow resistance) when the FVF gap was 1.5-2 times greater than D (g); (2) the divergent glottal angle gave lower pressure and greater flow than the convergent and uniform glottal angle as there were no FVF conditions; (3) the presence of the FVF decreased the effects of the glottal angle to a certain extent; and more importantly, (4) the presence of the FVF also moved the separation points downstream, straightened the glottal jet for a longer distance, decreased the overall laryngeal resistance, and reduced the energy dissipation, suggesting the significance of FVF in efficient voice production. These results may be incorporated in the phonatory models (physical or computational) for better understanding of vocal mechanics. The results might also be helpful in exploring the surgical and rehabilitative intervention of related voice problems.

The effect of tonal changes on voice onset time in Mandarin esophageal speech.

SUMMARY: The present study investigated the effect of tonal changes on voice onset time (VOT) between normal laryngeal (NL) and superior esophageal (SE) speakers of Mandarin Chinese. VOT values were measured from the syllables /pha/, /tha/, and /kha/ produced at four tone levels by eight NL and seven SE speakers who were native speakers of Mandarin. Results indicated that Mandarin tones were associated with significantly different VOT values for NL speakers, in which high-falling tone was associated with significantly shorter VOT values than mid-rising tone and falling-rising tone. Regarding speaker group, SE speakers showed significantly shorter VOT values than NL speakers across all tone levels. This may be related to their use of pharyngoesophageal (PE) segment as another sound source. SE speakers appear to take a shorter time to start PE segment vibration compared to NL speakers using the vocal folds for vibration.

DCEUS-based multiparametric perfusion imaging using pulse-inversion Bubblet decorrelation.

PURPOSE: This study aimed to clarify the influences of composite dynamic contrast-enhanced ultrasound (DCEUS) on multiparametric perfusion imaging (PPI) and to develop a novel PPI scheme through pulse-inversion Bubblet decorrelation (PIBD) to improve its contrast and detailed discriminability. METHOD: In in vivo perfusion experiments on rabbit kidneys, a pair of phase-inverted "Bubblets" was constructed. Phase-inverted raw radiofrequency echoes were reconstructed by using the maximum coefficients obtained from Bubblet decorrelation analysis and summed to form DCEUS loops. Nine perfusion parameters were estimated from these loops and color coded to create the corresponding PIBD-based PPIs. RESULTS: In addition to time-related PPIs, the contrast and detailed discriminability quantified by the average contrast and information entropy of intensity- and ratio-related PPIs were proportional to the microbubble detection sensitivity and microvascular discriminability evaluated by CTR in DCEUS techniques. Compared with the second harmonic, the CTR of DCEUS and the average contrast and information entropy of PPI were significantly improved by 9.03 ± 5.39 dB (P < 0.01), 6.39 ± 1.38 dB (P < 0.01), and 0.57 ± 0.15 (P < 0.05) in PIBD technique, respectively. CONCLUSIONS: As a multiparametric functional imaging technique, these improvements in the proposed scheme can be beneficial to accurately quantify and depict the hemodynamic perfusion features and details of tumor angiogenesis, and further can also assist clinicians in making a confirmed diagnosis.