In Vivo Ultrasound Shear Wave Elastography Assessment of Acute Compartment Syndrome in a Turkey Model.

OBJECTIVE: The aim of the work described here was to evaluate the objectivity and reproducibility of non-invasive intra-compartment pressure (ICP) measurement using ultrasound shear wave elastography (SWE) in a turkey model in vivo and to determine the biological and histologic changes in acute compartment syndrome (ACS). METHODS: Twenty-four turkeys were randomly divided into four groups based on the duration and fasciotomy of ACS created by infusion of up to 50 mm Hg in the tibialis muscle: group 1, ACS 2 h; group 2, ACS 4 h; group 3, ACS 2 h + fasciotomy 2 h; group 4, ACS 4 h + fasciotomy 2 h. For each turkey, the contralateral limb was considered the control. Time-synchronized measures of SWE and ICP from each leg were collected. Then turkeys were euthanized for histology and quantitative reverse transcription polymerase chain reaction (qRT-PCR) examination. RESULTS: All models created reproducible increases in ICP and SWE, which had a strong linear relationship (r = 0.802, p < 0.0001) during phase 1. SWE remained stable (50.86 ± 9.64 kPa) when ICP remained at 50.28 ± 2.17 mm Hg in phase 2. After fasciotomy, SWE declined stepwise and then normalized (r = 0.737, p < 0.0001). Histologically, the myofiber diameter of group 2 (82.31 ± 22.92 µm) and group 4 (90.90 ± 20.48 µm) decreased significantly (p < 0.01) compared with that of the control group (103.1 ± 20.39 µm); the interstitial space of all groups increased significantly (p < 0.01). Multifocal muscle damage revealed neutrophilic infiltration, degeneration, hemorrhage and necrosis, especially in group 4. Quantitative RT-PCR verified that interleukin-6 and heparin-binding EGF-like growth factor were significantly increased in group 4. CONCLUSION: SWE provided sensitive measurements correlating to ICP in a clinically relevant ACS animal model. Once ACS time was exceeded, progression to irreversible necrosis continued spontaneously, even after fasciotomy. SWE may help surgeons in the early detection, monitoring, prognosis and decision making on fasciotomy for ACS.

Contrast-free ultrasound imaging for blood flow assessment of the lower limb in patients with peripheral arterial disease: a feasibility study.

While being a relatively prevalent condition particularly among aging patients, peripheral arterial disease (PAD) of lower extremities commonly goes undetected or misdiagnosed due to its symptoms being nonspecific. Additionally, progression of PAD in the absence of timely intervention can lead to dire consequences. Therefore, development of non-invasive and affordable diagnostic approaches can be highly beneficial in detection and treatment planning for PAD patients. In this study, we present a contrast-free ultrasound-based quantitative blood flow imaging technique for PAD diagnosis. The method involves monitoring the variations of blood flow in the calf muscle in response to thigh-pressure-cuff-induced occlusion. Four quantitative metrics are introduced for analysis of these variations. These metrics include post-occlusion to baseline flow intensity variation (PBFIV), total response region (TRR), Lag0 response region (L0RR), and Lag4 (and more) response region (L4 + RR). We examine the feasibility of this method through an in vivo study consisting of 14 PAD patients with abnormal ankle-brachial index (ABI) and 8 healthy volunteers. Ultrasound data acquired from 13 legs in the patient group and 13 legs in the healthy group are analyzed. Out of the four utilized metrics, three exhibited significantly different distributions between the two groups (p-value < 0.05). More specifically, p-values of 0.0015 for PBFIV, 0.0183 for TRR, and 0.0048 for L0RR were obtained. The results of this feasibility study indicate the diagnostic potential of the proposed method for the detection of PAD.

Economics of Artificial Intelligence in Healthcare: Diagnosis vs. Treatment.

Motivation: The price of medical treatment continues to rise due to (i) an increasing population; (ii) an aging human growth; (iii) disease prevalence; (iv) a rise in the frequency of patients that utilize health care services; and (v) increase in the price. Objective: Artificial Intelligence (AI) is already well-known for its superiority in various healthcare applications, including the segmentation of lesions in images, speech recognition, smartphone personal assistants, navigation, ride-sharing apps, and many more. Our study is based on two hypotheses: (i) AI offers more economic solutions compared to conventional methods; (ii) AI treatment offers stronger economics compared to AI diagnosis. This novel study aims to evaluate AI technology in the context of healthcare costs, namely in the areas of diagnosis and treatment, and then compare it to the traditional or non-AI-based approaches. Methodology: PRISMA was used to select the best 200 studies for AI in healthcare with a primary focus on cost reduction, especially towards diagnosis and treatment. We defined the diagnosis and treatment architectures, investigated their characteristics, and categorized the roles that AI plays in the diagnostic and therapeutic paradigms. We experimented with various combinations of different assumptions by integrating AI and then comparing it against conventional costs. Lastly, we dwell on three powerful future concepts of AI, namely, pruning, bias, explainability, and regulatory approvals of AI systems. Conclusions: The model shows tremendous cost savings using AI tools in diagnosis and treatment. The economics of AI can be improved by incorporating pruning, reduction in AI bias, explainability, and regulatory approvals.

Detrusor overactivity assessment using ultrasound bladder vibrometry.

Objective. Detrusor overactivity (DO) is a urodynamic observation characterized by fluctuations in detrusor pressure (Pdet) of the bladder. Although detecting DO is important for the management of bladder symptoms, the invasive nature of urodynamic studies (UDS) makes it a source of discomfort and morbidity for patients. Ultrasound bladder vibrometry (UBV) could provide a direct and noninvasive means of detecting DO, due to its sensitivity to changes in elasticity and load in the bladder wall. In this study, we investigated the feasibility and applying UBV toward detecting DO.Approach. UBV and urodynamic study (UDS) measurements were collected in 76 neurogenic bladder patients (23 with DO). Timestamped group velocity squared (cg2) data series were collected from UBV measurements. ConcurrentPdetdata series were identically analyzed for comparison and validation. A processing approach is developed to separate transient fluctuations in the data series from the larger trend of the data and a DO index is proposed for characterizing the transient peaks observed in the data.Main Results.Applying the DO index as a classifier for DO produced sensitivities and specificities of 0.70 and 0.75 forcg2data series and 0.70 and 0.83 forPdetdata series respectively.Significance. It was found that DO can be feasibly detected from data series of timestamped UBV measurements. Collectively, these initial results are promising, and further refinement to the UBV measurement process is likely to improve and clarify its capabilities for noninvasive detection of DO.

Non-invasive assessment of urinary bladder compliance using ultrasound: first validation study based on clinical urodynamic study.

BACKGROUND: This study aims to validate a recently introduced non-invasive method, ultrasound bladder vibrometry (UBV), for the assessment of detrusor compliance in patients with neurogenic bladders. METHODS: The study was carried out on 79 adult patients with neurogenic bladders (60 male and 19 female). The UBV test was performed on each patient to measure the Lamb wave group velocity (cg ) in the anterior bladder wall at every 50mL volume increment throughout the filling phase. Bladder compliance was assessed based on the trend of Lamb wave group velocity squared (cg 2 ) versus volume. A compliance index was defined to differentiate between the compliant and non-compliant bladders. Results of the UBV compliance assessment were validated using the readings of the corresponding urodynamic studies as the clinical gold standard. RESULTS: The Patients' bladders were divided into non-compliant and compliant groups by an experienced urologist using the information in the urodynamic study (UDS) recordings. The compliance index defined on the basis of cg 2 showed a significant difference (P<0.008) between the compliant and non-compliant groups. The areas under the receiver operating characteristic curve were 0.813, with 95% CI ranging from 0.709 to 0.892. Under the optimal criterion, the bladder was considered as non-compliant if the compliance index was less than 100 mL∙s2/m2, resulting in a sensitivity and specificity of 86.4% and 71.9%, respectively. CONCLUSIONS: The results of this study demonstrate that UBV can be used as a non-invasive method for the determination of bladder compliance; thus, it can potentially serve as an alternative method to UDS for the appropriate patient groups.

Quantitative assessment of ensemble coherency in contrast-free ultrasound microvasculature imaging.

PURPOSE: Contrast-free visualization of microvascular blood flow (MBF) using ultrasound can play a valuable role in diagnosis and detection of diseases. In this study, we demonstrate the importance of quantifying ensemble coherence for robust MBF imaging. We propose a novel approach to quantify ensemble coherence by estimating the local spatiotemporal correlation (LSTC) image, and evaluate its efficacy through simulation and in vivo studies. METHODS: The in vivo patient studies included three volunteers with a suspicious breast tumor, 15 volunteers with a suspicious thyroid tumor, and two healthy volunteers for renal MBF imaging. The breast data displayed negligible prior motion and were used for simulation analysis involving synthetically induced motion, to assess its impact on ensemble coherency and motion artifacts in MBF images. The in vivo thyroid data involved complex physiological motion due to its proximity to the pulsating carotid artery, which was used to assess the in vivo efficacy of the proposed technique. Further, in vivo renal MBF images demonstrated the feasibility of using the proposed ensemble coherence metric for curved array-based MBF imaging involving phase conversion. All ultrasound data were acquired at high imaging frame rates and the tissue signal was suppressed using spatiotemporal clutter filtering. Thyroid tissue motion was estimated using two-dimensional normalized cross correlation-based speckle tracking, which was subsequently used for ensemble motion correction. The coherence of the MBF image was quantified based on Casorati correlation of the Doppler ensemble. RESULTS: The simulation results demonstrated that an increase in ensemble motion corresponded with a decrease in ensemble coherency, which reciprocally degraded the MBF images. Further the data acquired from breast tumors demonstrated higher ensemble coherency than that from thyroid tumors. Motion correction improved the coherence of the thyroid MBF images, which substantially improved its visualization. The proposed coherence metrics were also useful in assessing the ensemble coherence for renal MBF imaging. The results also demonstrated that the proposed coherence metric can be reliably estimated from downsampled ensembles (by up to 90 % ), thus allowing improved computational efficiency for potential applications in real-time MBF imaging. CONCLUSIONS: This pilot study demonstrates the importance of assessing ensemble coherency in contrast-free MBF imaging. The proposed LSTC image quantified coherence of the Doppler ensemble for robust MBF imaging. The results obtained from this pilot study are promising, and warrant further development and in vivo validation.

Early assessment of shear wave elastography parameters foresees the response to neoadjuvant chemotherapy in patients with invasive breast cancer.

BACKGROUND: Early prediction of tumor response to neoadjuvant chemotherapy (NACT) is crucial for optimal treatment and improved outcome in breast cancer patients. The purpose of this study is to investigate the role of shear wave elastography (SWE) for early assessment of response to NACT in patients with invasive breast cancer. METHODS: In a prospective study, 62 patients with biopsy-proven invasive breast cancer were enrolled. Three SWE studies were conducted on each patient: before, at mid-course, and after NACT but before surgery. A new parameter, mass characteristic frequency (fmass), along with SWE measurements and mass size was obtained from each SWE study visit. The clinical biomarkers were acquired from the pre-NACT core-needle biopsy. The efficacy of different models, generated with the leave-one-out cross-validation, in predicting response to NACT was shown by the area under the receiver operating characteristic curve and the corresponding sensitivity and specificity. RESULTS: A significant difference was found for SWE parameters measured before, at mid-course, and after NACT between the responders and non-responders. The combination of Emean2 and mass size (s2) gave an AUC of 0.75 (0.95 CI 0.62-0.88). For the ER+ tumors, the combination of Emean_ratio1, s1, and Ki-67 index gave an improved AUC of 0.84 (0.95 CI 0.65-0.96). For responders, fmass was significantly higher during the third visit. CONCLUSIONS: Our study findings highlight the value of SWE estimation in the mid-course of NACT for the early prediction of treatment response. For ER+ tumors, the addition of Ki-67improves the predictive power of SWE. Moreover, fmass is presented as a new marker in predicting the endpoint of NACT in responders.

In vivo assessment of the mechanical properties of crystalline lenses in a rabbit model using ultrasound elastography: Effects of ultrasound frequency and age.

PURPOSE: The occurrence of presbyopia and cataract is closely related to changes in the mechanical properties of the crystalline lens. There are no established methods so far for in vivo assessment. By introducing ultrasound elastography, we proposed group velocity (Vg) of an induced shear wave as a new biomarker to characterize the mechanical properties of the lens in our previous study. Here, we investigated the effect of the ultrasound frequency on measurement accuracy and validated the results with a conventional ex vivo compression testing. We also demonstrated a change trend in Vg and its correlation with age in a rabbit model. METHODS: Eight New Zealand white rabbits were fed normally from the fourth to seventh month. An ultrasound elastography system was developed to measure Vgin vivo on every eye once per month. The performances when using a high-frequency (L22-11v) and low-frequency (L11-4v) probe were compared. Rabbits were sacrificed after in vivo measurements by the end of the seventh month and this was followed by ex vivo ultrasound measurements and conventional compression tests on the extracted lenses. RESULTS: The results demonstrated that there were no significance differences in Vg between measurements with high-frequency (USE-HF) and low-frequency (USE-LF) probes in the same month-age group. The mean Vg and the standard deviation of four rabbits that were 7 months old were 2.37 ±â€¯0.24  m/s, 2.36 ±â€¯0.25 m/s, 2.43 ±â€¯0.26 m/s and 2.44 ±â€¯0.38 m/s, with USE-HF for ex vivo and in vivo measurements and USE-LF for ex vivo and in vivo measurements, respectively. There were no significant differences (p > 0.05) and they were all in agreement with the results of compression tests, which was 16.16 ±â€¯1.84 kPa in Young's modulus. The results also showed that Vg increased with age. In combination with the results of our previous study, Vg showed a relatively sharp increase from 2 to 5 months, while it had a slight increase from 5 to 7 months. CONCLUSIONS: The USE-HF and USE-LF has comparable accuracy in Vg measurements while USE-HF had an advantage regarding better spatial resolution. The change trend of Vg was in accord with the growth phase of New Zealand white rabbits, which usually results in sexual maturity at 5 months old. This implies that Vg can be used as a biomarker parameter for evaluating the mechanical properties of the lens undergoing physiological changes.

Pulsed vibro-acoustic method for assessment of osteoporosis & osteopenia: A feasibility study on human subjects.

In this paper we propose a new non-invasive ultrasound method, pulsed vibro-acoustic, for evaluating osteoporotic and osteopenic bone in humans. Vibro-acoustic method uses acoustic radiation force (ARF) to stimulate bone and the resulting acoustic signal can be used to characterize bone. The resulting acoustic signal is collected by a hydrophone at the skin surface. Wave velocity and numbers of intrinsic modes are used for analysis. Wave velocity is estimated using the received signal and maximum power mode of the decomposed signal is estimated using variational mode composition from different push points of ARF based on the cross-correlation method. A total of 27 adult volunteers, including healthy and those diagnosed with osteopenia and osteoporosis, were tested. Results of pulsed vibro-acoustic test on tibia of volunteers showed that healthy group could be differentiated from osteoporosis or osteopenia (p < 2 × 10-5). The results of our study support the feasibility of pulsed vibro-acoustic method for measuring mechanical properties of bone and the potential clinical utility of the proposed method for assessment of bone health.

Ultrasound Radiation Force for the Assessment of Bone Fracture Healing in Children: An In Vivo Pilot Study.

Vibrational characteristics of bone are directly dependent on its physical properties. In this study, a vibrational method for bone evaluation is introduced. We propose a new type of quantitative vibro-acoustic method based on the acoustic radiation force of ultrasound for bone characterization in persons with fracture. Using this method, we excited the clavicle or ulna by an ultrasound radiation force pulse which induces vibrations in the bone, resulting in an acoustic wave that is measured by a hydrophone placed on the skin. The acoustic signals were used for wave velocity estimation based on a cross-correlation technique. To further separate different vibration characteristics, we adopted a variational mode decomposition technique to decompose the received signal into an ensemble of band-limited intrinsic mode functions, allowing analysis of the acoustic signals by their constitutive components. This prospective study included 15 patients: 12 with clavicle fractures and three with ulna fractures. Contralateral intact bones were used as controls. Statistical analysis demonstrated that fractured bones can be differentiated from intact ones with a detection probability of 80%. Additionally, we introduce a "healing factor" to quantify the bone healing progress which successfully tracked the progress of healing in 80% of the clavicle fractures in the study.

Acoustoelasticity Analysis of Transient Waves for Non-Invasive In Vivo Assessment of Urinary Bladder.

A non-invasive method for measurement of the bladder wall nonlinear elastic behavior is presented. The method is based on acoustoelasticity modeling of the elasticity changes in bladder tissue modulus at different volumetric strain levels. At each volume, tissue strain is obtained from the real-time ultrasound images. Using acoustic radiation force, a transient Lamb wave is excited on the bladder wall and instantaneous modulus of shear elasticity is obtained from the 2-D Fourier analysis of the spatial-temporal dispersion maps. Measured elasticity and strain data are then used in an acoustoelasticity formulation to obtain the third order elastic coefficient, referred to as nonlinearity parameter A, and initial resting elasticity µ0. The method was tested in ex vivo porcine bladder samples (N = 9) before and after treatment with formalin. The estimated nonlinearity parameter, A, was significantly higher in the treated samples compared to intact (p < 0.00062). The proposed method was also applied on 16 patients with neurogenic bladders (10 compliant and 6 non-compliant subjects). The estimated nonlinearity parameter A was significantly higher in the non-compliant cases compared to the compliant (p < 0.0293). These preliminary results promise a new method for non-invasive evaluation of the bladder tissue nonlinearity which may serve as a new diagnostic and prognostic biomarker for management of the patients with neurogenic bladders.

Correlation of ultrasound bladder vibrometry assessment of bladder compliance with urodynamic study results.

PURPOSE OR OBJECTIVE: The objective of this study is to assess correlation between bladder wall mechanical properties obtained by ultrasound bladder vibrometry (UBV) and urodynamic study (UDS) measurements in a group of patients undergoing clinical UDS procedure. MATERIALS AND METHODS: Concurrent UBV and UDS were performed on 70 patients with neurogenic bladders (56 male and 14 female). Bladder wall mechanical properties measured by UBV at different filling volumes were correlated with recorded detrusor pressure (Pdet) values. Mean, median and standard deviation of correlation values were calculated and the significance of these observations was tested. RESULTS: Bladder wall mechanical properties obtained by UBV as group velocity squared and elasticity showed high correlations with Pdet measured at different volumes (median correlation 0.73, CI: 0.64-0.80 and 0.72, CI: 0.56-0.82 respectively). The correlation of group velocity squared and elasticity with Pdet were both significantly higher than 0.5. CONCLUSIONS: The results of this study suggest that UBV can closely monitor changes in bladder wall mechanical properties at different volumes in a group of patients undergoing UDS. The high correlation between UBV parameters and detrusor pressure measurements suggests that UBV can be utilized as a reliable and cost-effective tool for assessment of the bladder wall mechanical changes in a noninvasive fashion.

Noninvasive Evaluation of Bladder Wall Mechanical Properties as a Function of Filling Volume: Potential Application in Bladder Compliance Assessment.

PURPOSE: We propose a novel method to monitor bladder wall mechanical properties as a function of filling volume, with the potential application to bladder compliance assessment. The proposed ultrasound bladder vibrometry (UBV) method uses ultrasound to excite and track Lamb waves on the bladder wall from which its mechanical properties are derived by fitting measurements to an analytical model. Of particular interest is the shear modulus of bladder wall at different volumes, which we hypothesize, is similar to measuring the compliance characteristics of the bladder. MATERIALS AND METHODS: Three experimental models were used: 1) an ex vivo porcine model where normal and aberrant (stiffened by formalin) bladders underwent evaluation by UBV; 2) an in vivo study to evaluate the performance of UBV on patients with clinically documented compliant and noncompliant bladders undergoing UDS; and 3) a noninvasive UBV protocol to assess bladder compliance using oral hydration and fractionated voiding on three healthy volunteers. RESULTS: The ex vivo studies showed a high correlation between the UBV parameters and direct pressure measurement (R2 = 0.84-0.99). A similar correlation was observed for 2 patients with compliant and noncompliant bladders (R2 = 0.89-0.99) undergoing UDS detrusor pressure-volume measurements. The results of UBV on healthy volunteers, performed without catheterization, were comparable to a compliant bladder patient. CONCLUSION: The utility of UBV as a method to monitor changes in bladder wall mechanical properties is validated by the high correlation with pressure measurements in ex vivo and in vivo patient studies. High correlation UBV and UDS in vivo studies demonstrated the potential of UBV as a bladder compliance assessment tool. Results of studies on healthy volunteers with normal bladders demonstrated that UBV could be performed noninvasively. Further studies on a larger cohort are needed to fully validate the use of UBV as a clinical tool for bladder compliance assessment.