Papers by Valentina Hartwig
Journal of Applied Physiology, 2021
We demonstrated that the end tidal CO2 oscillation causes oscillations of delta and alpha bands. ... more We demonstrated that the end tidal CO2 oscillation causes oscillations of delta and alpha bands. The analysis of the regional field power showed that different cortical areas respond with different time delays to CO2 challenges. An opposite behavior was found for the end-tidal O2. We can suppose that the different cortical time delay response likely expresses specific ascending pathways to the cortex generated by chemoreceptor nuclei in the brainstem.
Electronics, 2021
In this review, the roles of detectors in various medical imaging techniques were described. Ultr... more In this review, the roles of detectors in various medical imaging techniques were described. Ultrasound, optical (near-infrared spectroscopy and optical coherence tomography) and thermal imaging, magnetic resonance imaging, computed tomography, single-photon emission tomography, positron emission tomography were the imaging modalities considered. For each methodology, the state of the art of detectors mainly used in the systems was described, emphasizing new technologies applied.
Medical & Biological Engineering & Computing, 2022
The original article has been corrected. Publisher's note Springer Nature remains neutral with re... more The original article has been corrected. Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Abstract: The TOUCH-HapSys collaborative project investigates the psychophysical basis of human t... more Abstract: The TOUCH-HapSys collaborative project investigates the psychophysical basis of human tactual perception in order to improve the efficiency and reliability of haptic displays. The present deliverable reports on the progress made in investigations on the basic tactual modes of active and passive touch. In psychophysical experiments MPI-T started to examine the principles of cue integration for active touch in higher-level perceptual tasks. UNIPI investigates basic aspects of active and passive touch by a combination of psychophysical and fMRI studies. For this purpose specific fMRI procedures are required, that have been developed and tested. Moreover, research has been done contributing to the development of specific fMRI-compatible actuator and stimulation technology. Finally, LSC concentrates on the design of multilevel collocated cutaneous and kinaesthetic haptic display. This research exploits and requires knowledge on active vs. passive touch and allows for improved i...
Independent component analysis (ICA) has been widely used to remove artefacts from multichannel b... more Independent component analysis (ICA) has been widely used to remove artefacts from multichannel biomedical signal acquisitions under the hypothesis that there is statistical independence among the original sources. However, the basic ICA model does not take into account the influence on the mixing process of the different paths from the signal sources to the sensors In this study we propose a convolutive mixtures model in order to overcome the limitations of the basic ICA approach. The independent components are estimated in the frequency domain, where the convolutive model can be solved through an instantaneous mixing model. The signals are reconstructed back to the observation space resolving the ICA model ambiguities. Simulations are carried out to optimize of the proposed method for convolutive mixtures of electrocardiographic (ECG) and motion artefacts signals. The algorithm is tested on real ECG signals acquired by wearable systems in order to preserve the QRS complex when the...
Italian Journal of Dermatology and Venereology, 2021
BACKGROUND Lower limb ulcers not responding to standard treatments after 8 weeks are defined as c... more BACKGROUND Lower limb ulcers not responding to standard treatments after 8 weeks are defined as chronic wounds, and they are a significant medical problem. Blue light (410-430 nm) proved to be effective in treating wounds, but there is a lack of data on chronic wounds in clinical practice. The study's purpose was to determine if Blue Light photobiomodulation with EmoLED medical device in addition to Standard of Care is more effective compared to Standard of care alone in promoting re-epithelialization of chronicwounds of lower limbs in 10 weeks. METHODS 90 patients affected by multiple or large area ulcers were enrolled. To minimize all variabilities, each patient has been used as control of himself. Primary endpoint was the comparison of the re-epithelialization rate expressed as a percentage of the difference between the initial and final area. Secondary endpoints were: treatment safety, pain reduction, wound area reduction trend over time, healing rate. RESULTS At week 10, the wounds treated with EmoLED in addition to Standard Care showed a smaller residual wound area compared to the wounds treated with Standard of Care alone: 42.1% vs 63.4% (p=0.029). The difference is particularly evident in venous leg ulcers, 33.3% vs 60.1% (p=0.007). 17 treated wounds and 12 controls showed complete healing at week 10. Patients showed a significant reduction in pain (p = 2*10-7). CONCLUSIONS Blue Light treatment in addition to Standard of Care accelerates consistently the re-epithelialization rate of chronic wounds, especially venous leg ulcers and increases the chances of total wound healing in 10 weeks.
Journal of Neuroscience Methods, 2021
BACKGROUND Disentangling physiological noise and signal of interest is a major issue when evaluat... more BACKGROUND Disentangling physiological noise and signal of interest is a major issue when evaluating BOLD-signal changes in response to breath holding. Currently-adopted approaches for retrospective noise correction are general-purpose, and have non-negligible effects in studies on hypercapnic challenges. NEW METHOD We provide a novel approach to the analysis of specific and non-specific BOLD-signal changes related to end-tidal CO2 (PETCO2) in breath-hold fMRI studies. Multiple-order nonlinear predictors for PETCO2 model a region-dependent nonlinear input-output relationship hypothesized in literature and possibly playing a crucial role in disentangling noise. We explore Retrospective Image-based Correction (RETROICOR) effects on the estimated BOLD response, applying our analysis both with and without RETROICOR and analyzing the linear and non-linear correlation between PETCO2 and RETROICOR regressors. RESULTS The RETROICOR model of noise related to respiratory activity correlated with PETCO2 both linearly and non-linearly. The correction affected the shape of the estimated BOLD response to hypercapnia but allowed to discard spurious activity in ventricles and white matter. Activation clusters were best detected using non-linear components in the BOLD response model. COMPARISON WITH EXISTING METHOD We evaluated the side-effects of standard physiological noise correction procedure, tailoring our analysis on challenging understudied brainstem and subcortical regions. Our novel approach allowed to characterize delays and non-linearities in BOLD response. CONCLUSIONS RETROICOR successfully avoided false positives, still broadly affecting the estimated non-linear BOLD responses. Non-linearities in the model better explained CO2-related BOLD signal fluctuations. The necessity to modify the standard procedure for physiological-noise correction in breath-hold studies was addressed, stating its crucial importance.
Wound Repair and Regeneration, 2020
The aim of this study is to ascertain whether the simultaneous measurement of hemoglobin O2 satur... more The aim of this study is to ascertain whether the simultaneous measurement of hemoglobin O2 saturation (StO2) and dimension of venous leg ulcers (VLU) by near infrared spectroscopy (NIRS) imaging can predict the healing course with protocols employing a conventional treatment alone or in combination with hyperbaric oxygen therapy (HBOT). NIRS 2D images of wound region were obtained in 81 patients with hard‐to‐heal VLU that had been assigned, in a randomized controlled clinical trial, to the following protocols: 30 HBOT sessions, adjunctive to the conventional therapy, either twice daily over 3 weeks (group A) or once daily over 6 weeks (group B), and conventional therapy without HBOT (group C). Seventy‐three patients completed the study with a total of 511 NIRS images being analyzed. At the end of treatment, wound area was significantly smaller in all three groups. However, at the 3‐week mark the wound area reduction tended to be less evident in group A than in the other groups. This trend continued up to the 6‐week end‐point when a significantly greater area reduction was found with group B (65.5%) and group C (56.8%) compared to group A (29.7%) (P < .01). Furthermore, a higher incidence of complete healing was noted with group B (20%) than with group A (4.5%) and group C (3.8%). When using a final wound reduction in excess of 40% to distinguish healing from nonhealing ulcers, it was found that only the former present NIRS StO2 values abating over the study period both at center and edge of lesions. In conclusion, NIRS analysis of StO2 and wound area can predict the healing course of VLU. Adjunctive HBOT significantly facilitates VLU healing compared to the conventional treatment alone. This positive action, however, becomes manifest only with a longer and less intensive treatment schedule.
Computer Methods and Programs in Biomedicine, 2018
Assessment of hand superficial oxygenation during ischemia/reperfusion in healthy subjects versus... more Assessment of hand superficial oxygenation during ischemia/reperfusion in healthy subjects versus systemic sclerosis patients by 2D near infrared spectroscopic imaging, Computer Methods and Programs in Biomedicine (2017),
Seminars in Arthritis and Rheumatism, 2019
Nearinfrared spectroscopic imaging of the whole hand: a new tool to assess tissue perfusion and p... more Nearinfrared spectroscopic imaging of the whole hand: a new tool to assess tissue perfusion and peripheral microcirculation in scleroderma,
Electronics Letters, 2019
Also according to the recent Directive by the European Parliament and the Council of the European... more Also according to the recent Directive by the European Parliament and the Council of the European Union, there is a need for a simple but reliable device to measure exposure to the magnetic field (MF) of magnetic resonance (MR) workers, especially given the continuing development of scanner using a higher static MF. Here the authors describe a novel device for assessing personal exposure to the MF. The time recording system can measure the static MF value at which the operator is exposed to and the field gradients due to his/her movements in the MR environment. The device does not require any cable for data management and transmission and it is able to record the instantaneous and cumulative exposition dose. The device can be used in all MR environments, for clinical or industrial applications.
Radiation Protection Dosimetry, 2018
Magnetic resonance imaging (MRI) is one of the most common sources of electromagnetic (EM) fields... more Magnetic resonance imaging (MRI) is one of the most common sources of electromagnetic (EM) fields as a diagnostic technique widely used in medicine. MRI staff during the working day is constantly exposed to static and spatially heterogeneous magnetic field. Also, moving around the MRI room to perform their functions, workers are exposed to slowly time-varying magnetic fields that induce electrical currents and fields in the body. The development of new exposure assessment methodologies to collect exposure data at a personal level using simple everyday equipment is hence necessary, also in view of future epidemiological studies. This paper describes the design and testing of a novel device for assessing personal exposure to static and time-varying magnetic fields during daily clinical practice. The dosemeter will be also used to ensure effective training of technicians who will be instructed to avoid, where possible, risk behaviour in terms of high exposure.
Annals of Work Exposures and Health, 2019
Concerning the occupational exposure in magnetic resonance imaging (MRI) facilities, the worker b... more Concerning the occupational exposure in magnetic resonance imaging (MRI) facilities, the worker behavior in the magnetic resonance (MR) room is of such particular importance that there is the need for a simple but reliable method to alert the worker of the highest magnetic field exposure. Here, we describe a quantitative analysis of occupational exposure in different MRI working environments: in particular, we present a field measurement method integrated with a software tool for an accurate mapping of the fringe field in the proximity of the magnetic resonance bore. Three illustrative assessment studies are finally presented, compared and discussed, considering an example of a realistic path followed by an MRI worker during the daily procedure. The results show that the basic restrictions set by ICNIRP can be exceeded during standard procedure even in 1.5 T scanners. Using the described simplified metrics, it is possible to introduce behavioral rules on how to move around an MRI room that could be more useful than a numerical limit to aid magnetic field risk mitigation strategies.
Annals of the Rheumatic Diseases, 2015
Proceedings - IEEE International Conference on Robotics and Automation, 2006
Functional brain exploration methodologies such as functional magnetic resonance imaging (fMRI) a... more Functional brain exploration methodologies such as functional magnetic resonance imaging (fMRI) are critical tools to study perceptual and cognitive processes. In order to develop complex and well-controlled fMRI paradigms, researchers are interested in using active interfaces with electrically powered actuators and sensors. Due to the particularity of the MR environment, safety and compatibility criteria have to be strictly followed to avoid risks to the subject under test, the operators or the environment, as well as to prevent artifacts in the images. This paper describes the design of an fMRI compatible mechatronic interface based on MR compatibility tests of materials and actuators. In particular, a statistical test is introduced to evaluate the presence of artifacts in the image sequences that could negatively affect the fMRI studies. The device with two degrees of freedom, allowing one translation with position-feedback along a horizontal axis and one rotation about a vertical axis linked to the translation, was realized to investigate the brain mechanisms of dynamic tactile perception tasks. It can be used to move and orient various objects below the finger for controlled tactile stimulation. The MR compatibility of the complete interface is shown using the statistical test as well as a functional study with a human subject.
Annual International Conference of the IEEE Engineering in Medicine and Biology - Proceedings, 2006
In this paper we propose an MR (magnetic resonance) compatible electrocutaneous stimulator able t... more In this paper we propose an MR (magnetic resonance) compatible electrocutaneous stimulator able to inject an electric current, variable in amplitude and frequency, into the fingertips in order to elicit tactile skin receptors (mechanoreceptors). The desired goal is to evoke specific tactile sensations selectively stimulating skin receptors by means of an electric current in place of mechanical stimuli. The field of application ranges from functional magnetic resonance imaging (fMRI) tactile studies to augmented reality technology. The device here proposed is designed using safety criteria in order to comply with the threshold of voltage and current permitted by regulations. Moreover, MR safety and compatibility criteria were considered in order to perform experiments inside the MR scanner during an fMRI acquisition for functional brain activation analysis. Psychophysical laboratory tests are performed in order to define the different evoked tactile sensation. After verifying the device MR safety and compatibility on a phantom, a test on a human subject during fMRI acquisition is performed to visualize the brain areas activated by the simulated tactile sensation.
Encyclopedia of Healthcare Information Systems
To evoke specific sensations related to specific types of mechanoreceptors, we consider here the ... more To evoke specific sensations related to specific types of mechanoreceptors, we consider here the possibility of using electrotactile stimulation, varying the amplitude and the frequency of the stimulating electric signal, but maintaining the same waveform. According to a different specificity of the mechanoreceptors at different mechanical stimulus (Kaczmarek, Webster, Bach-y- Rita, & Tompkins, 1991), there might exist receptor specificity for different amplitude and frequency of electrical stimulus. In this case it could be possible to stimulate specifically several types of mechanoreceptors maintaining the same waveform and varying only its amplitude or frequency, with the possibility of creating a different sensation for tactile studies and augmented reality applications.
Uploads
Papers by Valentina Hartwig