Speaking with mask in the COVID-19 era: Multiclass machine learning classification of acoustic and perceptual parameters.

The intensive use of personal protective equipment often requires increasing voice intensity, with possible development of voice disorders. This paper exploits machine learning approaches to investigate the impact of different types of masks on sustained vowels /a/, /i/, and /u/ and the sequence /a'jw/ inside a standardized sentence. Both objective acoustical parameters and subjective ratings were used for statistical analysis, multiple comparisons, and in multivariate machine learning classification experiments. Significant differences were found between mask+shield configuration and no-mask and between mask and mask+shield conditions. Power spectral density decreases with statistical significance above 1.5 kHz when wearing masks. Subjective ratings confirmed increasing discomfort from no-mask condition to protective masks and shield. Machine learning techniques proved that masks alter voice production: in a multiclass experiment, random forest (RF) models were able to distinguish amongst seven masks conditions with up to 94% validation accuracy, separating masked from unmasked conditions with up to 100% validation accuracy and detecting the shield presence with up to 86% validation accuracy. Moreover, an RF classifier allowed distinguishing male from female subject in masked conditions with 100% validation accuracy. Combining acoustic and perceptual analysis represents a robust approach to characterize masks configurations and quantify the corresponding level of discomfort.

Phonetic analysis during treatment with rapid maxillary expander.

OBJECTIVES: To investigate possible changes and/or device-related impairments in phonetic habits produced by rapid maxillary expansion (RME). MATERIALS AND METHODS: Thirty-five patients scheduled for RME were divided into two groups: Group A (banded two-arm Hyrax) and Group B (banded four-arm Hyrax). Speech samples were collected at six time points, before, during and after RME removal. Acoustical analysis was performed using PRAAT and BioVoice analysis tools. Ten volunteers completed a questionnaire on the acceptability of patient's speech. Maxillary dimensions and palatal volume were measured on dental casts before and after expansion using a digital gauge. RESULTS: Voice analysis showed an increase in the peak frequency of fricative consonants (/s/,/ʃ/) after expansion, whereas there was no change of formant frequencies of palatal consonants (/ɲ/,/ʎ/). Vowel /i/ displayed a lowering of the first formant frequency, and an increase in the second and third formant frequencies. After bonding, Group B showed both a greater reduction in the peak frequency of fricatives and a greater increase in the formant frequencies of palatal consonants than Group A. CONCLUSION: Rapid maxillary expansion causes a slight phonetic change in the acoustical parameters of both consonants and vowels. The two-arm Hyrax caused less speech impairment than the four-arm Hyrax during the treatment.

The ASC inflammasome adapter governs SAA-derived protein aggregation in inflammatory amyloidosis.

Extracellularly released molecular inflammasome assemblies -ASC specks- cross-seed Aß amyloid in Alzheimer's disease. Here we show that ASC governs the extent of inflammation-induced amyloid A (AA) amyloidosis, a systemic disease caused by the aggregation and peripheral deposition of the acute-phase reactant serum amyloid A (SAA) in chronic inflammatory conditions. Using super-resolution microscopy, we found that ASC colocalized tightly with SAA in human AA amyloidosis. Recombinant ASC specks accelerated SAA fibril formation and mass spectrometry after limited proteolysis showed that ASC interacts with SAA via its pyrin domain (PYD). In a murine model of inflammatory AA amyloidosis, splenic amyloid load was conspicuously decreased in Pycard-/- mice which lack ASC. Treatment with anti-ASCPYD antibodies decreased amyloid loads in wild-type mice suffering from AA amyloidosis. The prevalence of natural anti-ASC IgG (-logEC50 ≥ 2) in 19,334 hospital patients was <0.01%, suggesting that anti-ASC antibody treatment modalities would not be confounded by natural autoimmunity. These findings expand the role played by ASC and IL-1 independent inflammasome employments to extraneural proteinopathies and suggest that anti-ASC immunotherapy may contribute to resolving such diseases.

Effect of local blood flow in thermal regulation in diabetic patient.

The presence of dysautonomia in diabetic neuropathy is correlated with impairment of vasomotor activity that drives blood microcirculation. Microcirculation, in turn, plays an important role in thermoregulation. In this work, we investigate the changes between two different physiological conditions of diabetic patients, induced by FREMS application, in the control of skin temperature, using a minimally invasive experiment. Skin is warmed up to a fixed temperature (44 °C) for a few minutes, then the heat source is turned off, letting the skin recover its physiological temperature. Both temperature and local blood flow, the latter measured with laser Doppler, are monitored during the experiment. A simple model of the cooling phase is used to evaluate the time constants involved in the process. Results indicate that significant differences exist in the model parameters between the two conditions.

Selective biosorption of lanthanides onto Galdieria sulphuraria.

The recovering of trivalent Lanthanides from aqueous solutions, by biosorption process onto Galdieria sulphuraria lifeless cells, was investigated. Potentiometry, UV-Vis, FTIR-ATR spectroscopy and SEM-EDS analysis were used. All the experiments were performed at 25 °C, in 0.5 M NaCl. Ln3+ biosorption is greater in the 5-6 pH range with values ranging from 80 µmol/g to 130 µmol/g (dry weight). The adsorbed Ln3+ ions can be recovered at higher acidity (pH<1) and the biosorbent can be reused. Specific molecular interactions between Ln3+ ions and the functional groups on G. sulphuraria surface were highlighted. Particularly, proteins are involved if Ln3+=Pr3+, Sm3+, Eu3+, Tb3+, Dy3+, Tm3+, while Ce3+, Ho3+, Er3+ form bonds with carbohydrates. Finally, both proteins and carbohydrates are involved if Gd3+ and Yb3+. A Surface Complexation approach, with a good graphical fitting to potentiometric experimental collected data, was used to describe the biosorption mechanism. This study could be of great applicative utility for removing of trivalent actinides, from waste aqueous solutions, by biosorption. As well known the lanthanides were used as model to simulate the chemical behaviour of actinides in the same oxidation state.

Impact of the new european paediatric regulatory framework on ethics committees: overview and perspectives.

AIM: To evaluate the impact of the new European paediatric regulatory framework on the activities of Ethics Committees operating in Europe and to assess their involvement and interest in paediatric research. METHODS: Task-force in Europe for Drug Development for the Young Network of Excellence and Relating Expectations and Needs to the Participation and Empowerment of Children in Clinical Trials project set up an inventory of Ethics Committees existing in Europe and conducted a survey on their approach to paediatric trials. RESULTS: Ethics Committees operating in 22 European Countries participated in this survey. Results showed a high lack of knowledge, understanding and awareness of the current European paediatric regulatory framework and a lack of involvement of Ethics Committees in paediatric research, especially in terms of training and education, demonstrated also by the decreasing number of Ethics Committees answering exhaustively to the whole questionnaire. The majority of participating Ethics Committees expressed interest in future initiatives related to paediatric research. CONCLUSIONS: Despite a limited knowledge and understanding of the current paediatric regulatory framework, a significant number of Ethics Committees operating in Europe show interest in initiatives related to paediatric research. Networking may be an essential tool to be used to enhance Ethics Committees role in supporting paediatric research. Any initiative should be undertaken at European level in collaboration with European Union Institutions.

Voicing quantification is more relevant than period perturbation in substitution voices: an advanced acoustical study.

Quality of substitution voicing-i.e., phonation with a voice that is not generated by the vibration of two vocal folds-cannot be adequately evaluated with routinely used software for acoustic voice analysis that is aimed at 'common' dysphonias and nearly periodic voice signals. The AMPEX analysis program (Van Immerseel and Martens) has been shown previously to be able to detect periodicity in irregular signals with background noise, and to be suited for running speech. The validity of this analysis program is first tested using realistic synthesized voice signals with known levels of cycle-to-cycle perturbations and additive noise. Second, exhaustive acoustic analysis is performed of the voices of 116 patients surgically treated for advanced laryngeal cancer and recorded in seven European academic centers. All of them read out a short phonetically balanced passage. Patients were divided into six groups according to the oscillating structures they used to phonate. Results show that features related to quantification of voicing enable a distinction between the different groups, while the features reporting F(0)-instability fail to do so. Acoustic evaluation of voice quality in substitution voices thus best relies upon voicing quantification.

Tridimensional assessment of adductor spasmodic dysphonia pre- and post-treatment with Botulinum toxin.

Spasmodic dysphonia voices form, in the same way as substitution voices, a particular category of dysphonia that seems not suited for a standardized basic multidimensional assessment protocol, like the one proposed by the European Laryngological Society. Thirty-three exhaustive analyses were performed on voices of 19 patients diagnosed with adductor spasmodic dysphonia (SD), before and after treatment with Botulinum toxin. The speech material consisted of 40 short sentences phonetically selected for constant voicing. Seven perceptual parameters (traditional and dedicated) were blindly rated by a panel of experienced clinicians. Nine acoustic measures (mainly based on voicing evidence and periodicity) were achieved by a special analysis program suited for strongly irregular signals and validated with synthesized deviant voices. Patients also filled in a VHI-questionnaire. Significant improvement is shown by all three approaches. The traditional GRB perceptual parameters appear to be adequate for these patients. Conversely, the special acoustic analysis program is successful in objectivating the improved regularity of vocal fold vibration: the basic jitter remains the most valuable parameter, when reliably quantified. The VHI is well suited for the voice-related quality of life. Nevertheless, when considering pre-therapy and post-therapy changes, the current study illustrates a complete lack of correlation between the perceptual, acoustic, and self-assessment dimensions. Assessment of SD-voices needs to be tridimensional.

Are insulin resistance and non-alcoholic fatty liver disease associated with Peyronie's disease? A pilot study.

Risk factors for Peyronie's disease (PD) are serum lipid abnormalities, hypertension and type 2 diabetes mellitus (T2DM). Oxidative stress and inflammation are key-players in the pathogenesis of arterial diseases, leading to insulin resistance (IR), which is a major determinant of non-alcoholic fatty liver disease (NAFLD). We studied the potential relationship between PD, IR, and NAFLD. Forty-nine male patients were enrolled, fulfilling the well-accepted diagnostic criteria of stable PD. Fifty male individuals without PD, well-matched for age and BMI, were selected as the control group. Comorbidities (T2DM and hypertension), as well as the lipid profile and the glucometabolic asset, were evaluated. The triglycerides/HDL ratio (TG/HDL-C ratio) with a cut-off of ≥3 and the triglycerides-glucose index (TyG) with an optimal cut-point of 8.5 were used for diagnosis of IR and NAFLD, respectively. NAFLD diagnosis was confirmed by the presence of bright liver at ultrasonography. Hypertension was found more frequently in PD patients than in no-PD subjects (P=0.017), independently of age (P=0.99). Both IR and NAFLD were significantly associated with the presence of PD in our population of men (P=0.043 and 0.0001, respectively), no matter how old (P=0.11 and 0.74, respectively). At logistic regression, NAFLD was the only predictor of the PD presence (p=0.021). The AUROC of TyG to predict PD was 0.7437 (sensitivity 67.35% and specificity 80%) with a percentage of correctly classified patients of 73.74%. Oxidative stress markers were significantly associated with NAFLD. Testosterone level was significantly low in the subjects with NAFLD in cross-sectional analyses. Both factors, i.e., oxidative stress and hypogonadism, are central to PD pathogenesis. In conclusion, NAFLD and IR are strongly associated with PD. The pathogenic link between these conditions and the underlying mechanisms are only hypothetical and thoroughly summarized in the discussion.

[Impact of COVID-19 outbreak on urology surgical waiting lists and waiting lists prioritization strategies in the Post-COVID-19 era]. / Impacto del brote de COVID-19 en las listas de espera de cirugía urológica y estrategias de priorización en la era post-COVID-19.

Introduction: The suspension of most elective surgeries during COVID-19 pandemic caused the lengthening of urology surgical waiting lists. The objective of this study is to evaluate the impact of COVID-19 pandemic on urology surgical waiting list in a high-volume hospital. Methods: An observational descriptive study was designed. All patients included in the urology surgical waiting list of our high-volume center on May 1st 2020 (46 days after the suspension of elective surgery) were analyzed. Baseline variables, priority on the waiting list, main urological disease, type of scheduled surgery, and waiting time were recorded. Other variables recorded were the presence of a urinary catheter, number of accesses to the emergency department, evidence of COVID-19 infection, number of deaths and their cause. The waiting time for each disease was compared with the time to surgery in 2019. Results: A total of 350 patients were included. The mean (SD) time on the waiting list was 97.33 (55.47) days. Priority 1 patients, who normally should undergo surgery within 30 days, were on the waiting list for a mean (SD) time of 60.51 (20.14) days. They were mainly patients with ureteral lithiasis (25.6%), high-risk or muscle-invasive bladder cancer (20.9%) and high-risk prostate cancer (13.9%). The mean waiting time had already significantly exceeded the mean time to surgery in 2019 for radical cystectomy (p = 0.04) and URS (p = 0.003). Conclusions: The suspension of most elective surgeries due to COVID-19 had a significant impact on urology surgical waiting list of our high-volume center, especially in priority 1 group.

Impact of COVID-19 outbreak on urology surgical waiting lists and waiting lists prioritization strategies in the Post-COVID-19 era. / Impacto del brote de COVID-19 en las listas de espera de cirugía urológica y estrategias de priorización en la era post-COVID-19.

INTRODUCTION: The suspension of most elective surgeries during COVID-19 pandemic caused the lengthening of urology surgical waiting lists. The objective of this study is to evaluate the impact of COVID-19 pandemic on urology surgical waiting list in a high-volume hospital. METHODS: An observational descriptive study was designed. All patients included in the urology surgical waiting list of our high-volume center on May 1st 2020 (46 days after the suspension of elective surgery) were analyzed. Baseline variables, priority on the waiting list, main urological disease, type of scheduled surgery, and waiting time were recorded. Other variables recorded were the presence of a urinary catheter, number of accesses to the emergency department, evidence of COVID-19 infection, number of deaths and their cause. The waiting time for each disease was compared with the time to surgery in 2019. RESULTS: A total of 350 patients were included. The mean (SD) time on the waiting list was 97.33 (55.47) days. Priority 1 patients, who normally should undergo surgery within 30 days, were on the waiting list for a mean (SD) time of 60.51 (20.14) days. They were mainly patients with ureteral lithiasis (25.6%), high-risk or muscle-invasive bladder cancer (20.9%) and high-risk prostate cancer (13.9%). The mean waiting time had already significantly exceeded the mean time to surgery in 2019 for radical cystectomy (p = 0.04) and URS (p = 0.003). CONCLUSIONS: The suspension of most elective surgeries due to COVID-19 had a significant impact on urology surgical waiting list of our high-volume center, especially in priority 1 group.

Smartphones Offer New Opportunities in Clinical Voice Research.

Smartphone technology provides new opportunities for recording standardized voice samples of patients and sending the files by e-mail to the voice laboratory. This drastically improves the collection of baseline data, as used in research on efficiency of voice treatments. However, the basic requirement is the suitability of smartphones for recording and digitizing pathologic voices (mainly characterized by period perturbations and noise) without significant distortion. In this experiment, two smartphones (a very inexpensive one and a high-level one) were tested and compared with direct microphone recordings in a soundproof room. The voice stimuli consisted in synthesized deviant voice samples (median of fundamental frequency: 120 and 200 Hz) with three levels of jitter and three levels of added noise. All voice samples were analyzed using PRAAT software. The results show high correlations between jitter, shimmer, and noise-to-harmonics ratio measured on the recordings via both smartphones, the microphone, and measured directly on the sound files from the synthesizer. Smartphones thus appear adequate for reliable recording and digitizing of pathologic voices.

Objective analysis of the singing voice as a training aid.

A new tool for robust tracking of fundamental frequency is proposed, along with an objective measure of main singing voice parameters, such as vibrato rate, vibrato extent, and vocal intonation. High-resolution Power Spectral Density estimation is implemented, based on AutoRegressive models of suitable order, allowing reliable formant tracking also in vocalizations characterized by highly varying values. The proposed techniques are applied to about 1000 vocalizations, coming from both professional and non-professional singers, and show better performance as compared to classical Fourier-based approaches. If properly implemented, and with a user-friendly interface, the new tool would allow real-time analysis of singing voice. Hence, it could be of help in giving non-professional singers and singing teachers reliable measures of possible improvements during and after training.

Laparoscopic pancreatectomy: Did the indications change? A review from literature.

Pancreatic Cancer (PC) is the fourth cause of death for tumors in Western countries. Symptoms are not specific, and can vary according to the tumor size and place. Diagnostic workup includes CA 19-9, CT and MRI. Surgery is the only treatment for PC, associated to radio-chemo therapy. Laparoscopic approaches are actually used for PC treatment in few specialized centers, and could be an alternative to laparotomic surgery. The aim of our study is to evaluate the efficacy of laparoscopy for PC treatment compared to laparotomy. We reviewed 19 articles in literature to assess the feasibility and efficacy of Laparoscopic Distal Pancreatectomy (LDP) and Laparoscopic Pancreaticoduodenectomy (LPD). The results have shown that LDP is nowadays a safe technique, and the outcomes are comparable to laparotomic surgery. Regarding to LPD instead, results are controversial and the data are still not sufficient to consider this technique as a valid alternative to laparotomic surgery.

Acute effects of amiodarone administration on thyroid function in patients with cardiac arrhythmia.

Because little has been published on early effects of treatment with amiodarone on thyroid function, we studied serum total and free thyroid hormone, reverse T3, and TSH levels in patients with cardiac arrhythmias during the first 10 days of treatment with a loading dose of amiodarone by iv infusion. Twenty-four patients were enrolled in the study. A standardized loading regimen for the i.v. infusion of amiodarone was used. The protocol provided the i.v. infusion of 20 mg/kg per day on day 1, the i.v. infusion of 10 mg/kg per day on day 2, then 600 mg/day per os for 7-10 days, and finally, in patients chronically treated with the drug, the dose was gradually reduced to 400-200 mg/day per os. Total and free concentrations of T4 tended to progressively and significantly increase (P < 0.0001 repeated measures ANOVA) starting from the fourth day of therapy, whereas total T3 decreased from the second day progressively (P < 0.0001) throughout the study; free T3 did not significantly change. TSH levels early and significantly (P < 0.001, by ANOVA) increased throughout the study, starting from the first day of therapy and reaching at 10 days a value 2.7 times higher than the basal value. Reverse T3 levels progressively and significantly (after 2 days of treatment) increased and paralleled the TSH values, reaching at the 10th day a value about 2 times higher than basal value. In conclusion, our data suggest that after i.v. treatment with amiodarone: 1) TSH is the first hormone to change significantly followed by reverse T3, T4, and T3; 2) the progressive fall of T3 levels reflects an inhibition of the peripheral conversion of T4 to T3; 3) the observed later increase of total and free T4 levels may be explained by a contribution of direct thyroidal stimulation by TSH and/or by a reduction in T4 clearance.

Evidence that atrial natriuretic peptide tissue extraction is not changed by large increases in its plasma levels induced by pacing in humans.

Atrial natiurectic peptide (ANP) is a cardiac hormone with a very short plasma half-life, which plays an important role in a variety of clinical conditions associated with an increase in pressure and/or volume overload on the heart. The MCR of the hormone is considered to represent a stable parameter, reflecting the uptake and degradation rate of ANP by the periphery, only scarcely affected by rapid oscillations of circulating levels. To evaluate the extent to which MCR is affected by rapid and large variations of circulating levels of the hormone, we measured MCR in five patients with different degrees of myocardial function (from normal to severely impaired), in whom changes in ANP levels were induced by atrial and/or ventricular pacing. Cardiac output was simultaneously measured by thermodilution to calculate whole body extraction of ANP. During constant i.v. infusion of [125I]ANP, the hormone MCR was determined both under basal conditions (at tracer equilibration, 20-30 min after the start of infusion) and during atrial and ventricular pacing. Pacing maneuvers, begun 50 min after the start of infusion, induced a marked and rapid increase in endogenous plasma ANP values in all patients (on the average, 3,7-fold compared to basal values; range, 1.8-5.68), whereas corresponding values of [125I]ANP only minimally changed. The MCR of ANP (3.62 +/- 1.06 L/min, mean +/- SD) slightly decreased (by repeated measures ANOVA, P = 0.0458) during atrial and ventricular pacing procedures (3.35 +/- 1.03 and 3.15 +/- 0.74 L/min, respectively), reaching a mean value of 88.7 +/- 9.0% compared to basal. The small decrease in MCR could be almost completely ascribed to hemodynamic factors; indeed, basal cardiac output (5.76 +/- 1.70 L/min) was found, on the average, to be slightly decreased during atrial and ventricular pacing (5.28 +/- 1.46 and 5.16 +/- 1.33 L/min, respectively), and so whole body extraction of the hormone, measured before pacing (50.0 +/- 12%), remains stable throughout the study period (50.4 +/- 10.6% and 49.6 +/- 10% during atrial and ventricular pacing, respectively). Our findings demonstrate that degradative mechanisms involved in ANP clearance are not saturable at least for acute elevations of ANP plasma levels up to 3-5 times the basal level.

Cancer patients' search for information.

This study explored the information-seeking behavior of 257 cancer patients or their relatives who received specific, treatment-related information from the Illinois office of the Cancer Information Service (CIS); it also explored the information-seeking behavior of a sample of 262 other cancer patients matched for age, gender, race, cancer site, and type of hospital where first seen. Among the matched patients, 53% sought information from at least one source besides their physicians. These information seekers were similar to the selected CIS patients in many respects. Compared with patients who did not seek information, both CIS patients and these other information seekers were more likely to have felt more stressed when first diagnosed, to have sought a second opinion, to have been seen at more hospitals and by more physicians since diagnosis, to prefer greater information about and involvement in their treatment plans, and to have been less confident that physicians always have the most current cancer knowledge. The majority of both information-seeking groups sought explanatory information about their cancer or treatment, and most wanted information just after their diagnosis and before starting treatment. Those in the comparison sample, however, had less well-defined questions and consulted fewer sources; only a few of them received the type of information provided by the CIS, and they were less likely to discuss with their physicians the information obtained from various sources.

In vivo functional antagonism between isoproterenol and bronchoconstrictants in the dog.

The functional antagonism between isoproterenol and methacholine, histamine and serotonin, as described in vitro in respiratory smooth muscle was explored in vivo in a canine model. Infusions of isoproterenol were administered during brief peaks of bronchospasm produced by aerosolized methacholine and histamine, or during sustained bronchospasm produced by infused serotonin. In eight mongrel dogs anesthetized with pentobarbital sodium, the mean protection by infused isoproterenol against methacholine challenge decreased from 60.6 to 29.1% as the mean lung resistance (RL) was increased from 78 to 232% over base line by a fourfold increase in methacholine (P less than 0.002). In six dogs, the mean protection by isoproterenol against histamine decreased from 55.5 to 26.9% as the opposing RL increased from 80 to 182% over base line with a fourfold increase in histamine (P less than 0.02). However, with serotonin infusions there was only a small 18% mean decrease in protection (P = 0.05), associated with a correspondingly small 37% mean increase in dose of serotonin despite a 269% mean increase in resistance (P = 0.02). In all cases, the loss of protection correlated more closely with the dose of constrictant than the resistance increase over base line. These findings demonstrate in vivo functional antagonism between isoproterenol and the dose of bronchoconstrictant but not necessarily resistance increase per se.

Adaptive SVD-based AR model order determination for time-frequency analysis of Doppler ultrasound signals.

The short-time Fourier transform provides a picture of the spectral components temporal location in time-varying signals, but its performance is limited by the intrinsic trade-off between time and frequency resolutions. In the present study, this problem is addressed using a spectral estimator based on a combination of the autoregressive (AR) modeling technique and a new automatic model order selection method. The order estimation is achieved by means of the singular value decomposition (SVD) of an appropriate data matrix in conjunction with a new criterion (dynamic mean evaluation, DME). The latter is used to decide which singular values correspond to the signal and which to the noise subspaces, avoiding an a priori threshold definition, thus giving the variable AR model order on consecutive short-time segments. Combination of the AR high frequency resolution capabilities and the SVD plus DME robustness and simplicity make the overall method reliable in many practical applications, mainly in the analysis of time-varying signals corrupted by noise. The proposed procedure has been applied to benchmark as well as to Doppler signal analysis. Some examples are reported confirming the above-mentioned properties.

Recursive autoregressive spectral maps for ocular pathology detection.

This article presents a new approach to the problem of obtaining topological maps for tissue characterization, based on spectral parameters extracted from radio frequency (RF) backscattered ultrasonic signals. The spectral parameter we deal with is the power spectral density centroid, since it is an efficient indicator of the tissue microstructure characteristics as far as the particle dimensions are concerned. The spectral analysis of RF ultrasonic echoes is performed using a recursive least-squares scheme with a variable forgetting factor, based on low-order autoregressive models. The proposed technique is particularly tailored to the differentiation of ocular pathologies; moreover, it is capable of tracking the spatial high-varying signal characteristics. The proposed approach was tested on simulated signals and on a gel suspension of calibrated latex spheres; finally, it was applied to signals scattered by in vitro eye specimens, giving satisfactory results in terms of frequency resolution and computational efficiency. The reduced computational burden allows an on-line implementation of the procedure. Topological spectral maps, combined with the conventional B-mode display, may offer a complete and integrated diagnostic tool, able to locally characterize the investigated tissue region in terms of amplitude and frequency shift of the corresponding echoes.