Wearable, Fiber-less, Multi-Channel System for Continuous Wave Functional Near Infrared Spectroscopy Based on Silicon Photomultipliers Detectors and Lock-In Amplification.

Development and in-vivo validation of a Continuous Wave (CW) functional Near Infrared Spectroscopy (fNIRS) system is presented. The system is wearable, fiber-less, multi-channel (16×16, 256 channels) and expandable and it relies on silicon photomultipliers (SiPMs) for light detection. SiPMs are inexpensive, low voltage and resilient semiconductor light detectors, whose performances are analogous to photomultiplier tubes (PMTs). The advantage of SiPMs with respect to PMTs is that they allow direct contact with the scalp and avoidance of optical fibers. In fact, the coupling of SiPMs and light emitting diodes (LEDs) allows the transfer of the analog signals to and from the scalp through thin electric cables that greatly increase the system flexibility. Moreover, the optical probes, mechanically resembling electroencephalographic electrodes, are robust against motion artifacts. In order to increase the signal-to-noise-ratio (SNR) of the fNIRS acquisition and to decrease ambient noise contamination, a digital lock-in technique was implemented through LEDs modulation and SiPMs signal processing chain. In-vivo validation proved the system capabilities of detecting functional brain activity in the sensorimotor cortices. When compared to other state-of-the-art wearable fNIRS systems, the single photon sensitivity and dynamic range of SiPMs can exploit the long and variable interoptode distances needed for estimation of brain functional hemodynamics using CW-fNIRS.

Thermal alterations in patients with inflammatory diseases: a comparison between psoriatic and rheumatoid arthritis.

Functional infrared imaging (fIRI) is used to provide information on circulation, thermal properties and thermoregulatory function of the cutaneous tissue in several clinical settings. This study aims to evaluate the application of fIRI in rheumatoid arthritis (RA) assessment, evaluating the thermoregulatory alterations due to joint inflammation in RA patients both in basal conditions and after a mild functional (isometric) exercise, using the same protocol we projected in our recent work on psoriatic arthritis (PsA); fIRI outcomes were compared with those provided by power-Doppler ultrasonography. Ten patients with RA and 11 healthy controls were enrolled in the study. The cutaneous temperature dynamics of 20 regions of interest located on the dominant hand were recorded by means of high-resolution thermal imaging at baseline and after a functional exercise. RA patients showed lower thermal parameters compared to healthy controls, suggesting that the RA-related inflammatory state alters the normal thermal properties of the skin overlying inflamed joints. These results are different from PsA data observed in the previous study. fIRI applied to the study of the response to a functional stimulus may represent an innovative, non-invasive, and operator-independent method for the assessment of early RA.

Joint functional impairment and thermal alterations in patients with Psoriatic Arthritis: A thermal imaging study.

BACKGROUND: Functional infrared imaging (fIRI) is used to provide information on circulation, thermal properties and thermoregulatory function of the cutaneous tissue in several clinical settings. OBJECTIVES: This study aims to evaluate the application of fIRI in Psoriatic Arthritis (PsA) assessment, evaluating the thermoregulatory alterations due to joint inflammation in PsA patients both in basal conditions and after a mild functional (isometric) exercise; fIRI outcomes were compared with those provided by Power Doppler Ultrasonography (PWD-US). METHODS: 10 patients with PsA and 11 healthy controls were enrolled in the study. The cutaneous temperature dynamics of 20 regions of interest located on the dominant hand were recorded by means of high-resolution thermal imaging at baseline and after a functional exercise. RESULTS: Higher temperature values and faster temperature variations characterized the PsA group compared to healthy controls, confirming that the PsA-related inflammatory state alters the normal thermal proprieties of the skin overlying inflamed joints. fIRI outcomes correlated with the PWD-US findings. CONCLUSIONS: fIRI applied to the study of the response to a functional stimulus may represent an innovative, non-invasive, and operator-independent method for the assessment of peripheral PsA.

Differential diagnosis of Raynaud's phenomenon based on modeling of finger thermoregulation.

Raynaud's phenomenon (RP) is a vasospastic disorder of small arteries, pre-capillary arteries, and cutaneous arteriovenous shunts of the extremities, typically induced by cold exposure and emotional stress. RP is either primary (PRP) or secondary to connective tissue diseases such as systemic sclerosis (SSc). Early differential diagnosis is crucial in order to set the proper therapeutic strategy. To this goal, thermal infrared imaging data from 18 healthy controls (HCs) and 48 RP patients (20 PRP, 28 SSc) were processed through a model for a second-order time-invariant system with exponential critically damped dynamic response. Subject classification on the basis of the model parameters provides 100% true-positive discrimination for RP patients (PRP and SSc) and healthy, and 90% of correct classification within the group of patients. The proposed method may provide useful hints for early differential diagnosis in the assessment of RP disease.

Thermal signature of fear conditioning in mild post traumatic stress disorder.

Fear conditioning has been proposed as an important factor involved in the etiology of posttraumatic stress disorder (PTSD). We examined fear processing in PTSD patients with mild symptoms and in individuals who did not develop symptoms (both groups consisting of victims of a bank robbery), through the study of fear-conditioned response. Conditioned responses were quantified by the skin conductance response (SCR) and the facial thermal response, the latter being measured by high-resolution functional thermal infrared (fIR) imaging. We found: (a) a change of the physiological parameters with respect to the baseline condition in both control subjects and PTSD patients during the conditioning phase; (b) the permanence of the conditioning effect in the maintenance phase in both control and PTSD patients; (c) patients and controls did differ for the variation across the phases of the physiological parameters rather than for their absolute values, showing that PTSD patients had a prolonged excitation and higher tonic component of autonomic activity. These results, although preliminary, indicate that the analysis of SCR and facial thermal response during the conditioning paradigm is a promising psychometric method of investigation, even in the case of low level of PTSD symptom severity. To the best of our knowledge, this study is the first attempt to discriminate between control subjects and PTSD patients with mild symptoms through infrared thermal imaging. It may suggest feasible approaches for diagnostic screening in the early phases of the disorder and in the assessment of preventive measures and therapies.

Long-term outcome of hepatitis B virus-related Chronic Hepatitis under protracted nucleos(t)ide analogues.

Long-term outcome of patients with chronic hepatitis B virus (HBV) infection under continuous nucleos(t)ide analogues (NUCs) has been poorly elucidated. We enrolled 121 anti-HBe-positive patients into a prospective surveillance programme while on (>36 months) NUCs therapy. HBV-DNA clearance, add-on therapy and safety were evaluated. Development of cirrhosis, events of liver decompensation and hepatocellular carcinoma (HCC) during the follow-up were the main endpoints, as the complication-free survival. At baseline, 74 patients (61%) had chronic hepatitis, the remainders a cirrhotic liver. HBV-DNA levels >38 000 IU/mL were discovered in 103 patients. At enrolment, 79 patients were naïve to NUCs treatment. Lamivudine monotherapy (n = 70) or a different NUC (n = 51) was administered. At month 6 of therapy, HBV-DNA clearance was documented in 88 patients (73%). Treatment schedule was modified in 52 patients due to breakthrough or suboptimal response. During a mean follow-up of 6 ± 3 years, viral clearance was achieved in the majority of patients. Ten of 74 patients (13.5%) with chronic hepatitis progressed to cirrhosis, 1 patient developed a HCC. In the 47 patients with cirrhosis at presentation, HCC occurred in 14 (30%) and liver decompensation in 5 (11%). The 5 and 10-year event-free survivals were, respectively, 89.3% (95% CI, 81.7 -96.9) and 75.6% (95% CI, 61.5 -89.7) for patients with chronic hepatitis, and 70.2% (95% CI, 56.3 -84.1) and 40.4% (95% CI, 16.9 -63.9) for those with cirrhosis. Protracted, effective treatment with oral NUCs affects the natural history of chronic HBV infection by reducing the incidence of cirrhosis and risk of complications, but does not guarantee against the development of HCC in cirrhosis at presentation.

Iloprost treatment summer-suspension: effects on skin thermal properties and cytokine profile in systemic sclerosis patients.

AIM: Aim of the study was to assess whether Iloprost treatment summer suspension modifies systemic cytokines levels, cutaneous thermal properties and functional response to a cold-induced stress in patients affected by systemic sclerosis (SSc). METHODS: Twenty-eight patients fulfilling the American College of Rheumatology (ACR) criteria for SSc were included in the study. Patients recorded number, duration and pain-severity of Raynaud phenomenon (RP). Pain-severity was determined by a visual analog scale. Cytokines expression and production in peripheral blood mononuclear cells and serum were evaluated by RT-PCR and ELISA assay. Basal finger temperature (Tb), distal-dorsal difference temperature (DTdd) and thermal recovery time (tr) from cold stress were measured by means of functional infrared imaging (fIR). Measurements were performed in late spring, during routine Iloprost therapy (1-3 days infusion of 0.5-2 ng/kg every month), and in late summer after a therapy-withdrawal period. RESULTS: Deterioration of SSc patients' skin thermal properties was observed in the period of therapy withdrawal (Tb reduction and tr enhancement; no DTdd differences) despite the improvement in symptoms of RP. A reduction in IL-12/23p40 gene expression was recorded after therapy withdrawal and a direct correlation between IL-12/23p40 and IL-23p19 gene expression was observed, stronger after therapy suspension. CONCLUSION: Our data suggest that Iloprost treatment summer suspension may induce the loss of the therapy beneficial effect on microcirculation despite the objective reduction of RP, thus favouring a continuous use of Iloprost in absence of severe side effects. Iloprost showed to modulate only IL-23 expression corroborating the idea that this cytokine is crucial for SSc development and progression.

Comparison of cutaneous termic response to a standardised warm up in trained and untrained individuals.

AIM: Warm up prior to exercise induces an increased production of metabolic heat, which triggers the thermoregulatory system to initiate heat loss mechanisms. Variations in cutaneous tissue temperature have been already reported in trained subjects, by means of high resolution thermal imaging. Purpose of this paper was to quantitatively evaluate, by means of infrared thermography, the differences in the cutaneous temperature among trained and untrained subjects. METHODS: Forty male volunteers performed a standard warm up exercise on a stationary cycle, divided in three steps: 1) 0-5 minutes at 100 Watt; 2) 5-10 minutes at 130 Watt; and 3) 10-15 minutes at 160 Watt. Thermal images from thorax and upper limbs were collected during the exercise. Heart rate was also measured. RESULTS: In comparison to baseline, trained subjects exhibited a significant temperature reduction in the third step (trunk, P<0.01; upper limbs, P<0.009), while no difference was observed in untrained subjects. In the comparison between groups, a statistically significant difference was observed in both regions of interest, in the second (trunk, P<0.01; upper limbs, P<0.02), and in the third step (trunk, P<0.0002; upper limbs, P<0.0008). During the whole exercise, heart rate increased progressively in all participants, but more markedly in untrained subjects. CONCLUSION: Cutaneous thermoregulatory response differs among trained and untrained participants. Infrared thermal imaging is useful in detecting these differences, providing additional data to the physiological evaluation of subjects performing sport activities.

Functional infrared imaging of paroxysmal ischemic events in patients with Raynaud's phenomenon.

The use of thermal infrared (IR) imaging together with the study of the thermal recovery from a controlled cold challenge has been proposed in the diagnosis and follow-up of therapeutic response of Raynaud's Phenomenon (RP) and Systemic Sclerosis (SSc). The controlled cold challenge test usually performed during IR investigations may induce a RP in patients with the latter condition. In our Institution we routinely perform capillaroscopy and thermal IR to follow-up SSc patients. In this paper, we describe the thermal recovery patterns shown by two SSc patients (a 40 year-old male with diffuse variant of SSc and a 71 year-old female with a limited variant of SSc) who presented ischemic and paroxysmal RP attack while recovering from the routine controlled cold challenge test. During RP attack, the cutaneous temperature of some fingers continued to decrease for some minutes even after the cessation of the cold stress. To the best of our knowledge, to date, no literature report has documented the thermal behaviour of SSc patients' fingers which occasionally present ischemic and paroxysmal response. Triggering of ischemic RP attack appears to not rely only on morphological and structural finger impairment, but also upon other aspects, like the emotional attitude of the subject and the possible discomfort experienced with the proceeding of the functional cold stress test.

Elevated response of human amygdala to neutral stimuli in mild post traumatic stress disorder: neural correlates of generalized emotional response.

Previous evidence from functional magnetic resonance imaging (fMRI) studies has shown that amygdala responses to emotionally neutral pictures are exaggerated at a group level in patients with severe post-traumatic stress disorder (PTSD) [Hendler T, Rotshtein P, Yeshurun Y, Weizmann T, Kahn I, Ben-Bashat D, Malach R, Bleich A (2003) Neuroimage 19(3):587-600]. The present fMRI study tested the hypothesis that amygdala responses are elevated not only in response to negative pictures but also to neutral pictures as a function of disease severity in patients with mild symptoms and in subjects who did not develop symptoms. To this end, fMRI scans were performed in 10 patients with mild PTSD and 10 healthy controls (both victims of a bank robbery), during the execution of a visuo-attentional task in which they were asked to observe emotionally negative or neutral pictures. Control subjects showed enhanced amygdala responses to emotionally negative stimuli compared to neutral stimuli. On the contrary, PTSD patients were characterized by high amygdala responses to both neutral and emotional pictures, with no statistically significant difference between the two classes of stimuli. In the entire group, we found correlations among the severity of the PTSD symptoms, task performance, and amygdala activation during the processing of neutral stimuli. Results of this study suggest that amygdala responses and the selectivity of the emotional response to neutral stimuli are elevated as a function of disease severity in PTSD patients with mild symptoms.

Comparison of thermal infrared and laser doppler imaging in the assessment of cutaneous tissue perfusion in scleroderma patients and healthy controls.

In this study we propose a non-invasive method to calculate blood flow by means of thermal infrared imaging and bio-heat transfer modeling. The method is able to provide high time-resolution series of cutaneous blood flow images with the same spatial resolution of the thermal images. The method was tested against a standard laser Doppler imaging system, which to date is considered the gold standard for non-invasive assessment of cutaneous blood flow, on both healthy subjects and patients suffering from systemic sclerosis (SSc; a pathological condition with microvessel endothelium injury). Twenty healthy subjects and twenty SSc patients simultaneously underwent laser Doppler and thermal imaging of the dorsum of the hand. A linear correlation between perfusion values obtained with the two methods was found for the healthy control group (R = 0.85, Pearson Product Moment Correlation). A significant correlation was not observed for the SSc patient group. The results of this study suggest that combined laser Doppler, thermal imaging and bio-heat transfer modeling could effectively discriminate between healthy vs. impaired conditions of the cutaneous tissue thermal properties and cutaneous vasculature. Such method, in addition to providing a potential effective imaging-based tool for a variety of biomedical and clinical applications ranging from diagnostics to treatment follow-up, may help the understanding of the morphological and functional impairment secondary to the disease. The thermal imaging-based method provided faster and better time-resolved imaging of cutaneous perfusion than standard laser Doppler techniques as the thermal cameras can provide up to 100 complete 524 x 524 pixel images per second, thus allowing real time monitoring of tissue perfusion rates.

Hypothalamus, sexual arousal and psychosexual identity in human males: a functional magnetic resonance imaging study.

In a recent functional magnetic resonance imaging study, a complex neural circuit was shown to be involved in human males during sexual arousal [A. Ferretti et al. (2005) Neuroimage, 26, 1086]. At group level, there was a specific correlation between penile erection and activations in anterior cingulate, insula, amygdala, hypothalamus and secondary somatosensory regions. However, it is well known that there are remarkable inter-individual differences in the psychological view and attitude to sex of human males. Therefore, a crucial issue is the relationship among cerebral responses, sexual arousal and psychosexual identity at individual level. To address this issue, 18 healthy male subjects were recruited. Their deep sexual identity (DSI) was assessed following the construct revalidation by M. Olivetti Belardinelli [(1994) Sci. Contrib. Gen. Psychol., 11, 131] of the Franck drawing completion test, a projective test providing, according to this revalidation, quantitative scores on 'accordance/non-accordance' between self-reported and psychological sexual identity. Cerebral activity was evaluated by means of functional magnetic resonance imaging during hard-core erotic movies and sport movies. Results showed a statistically significant positive correlation between the blood oxygen level-dependent signal in bilateral hypothalamus and the Franck drawing completion test score during erotic movies. The higher the blood oxygen level-dependent activation in bilateral hypothalamus, the higher the male DSI profile. These results suggest that, in male subjects, inter-individual differences in the DSI are strongly correlated with blood flow to the bilateral hypothalamus, a dimorphic brain region deeply implicated in instinctual drives including reproduction.

Thermal signatures of emotional arousal: a functional infrared imaging study.

Functional Infrared Imaging was used to study the facial thermal signatures of three fundamental emotional conditions: stress, fear and pleasure arousal. Facial cutaneous temperature and its topographic distribution exhibited specific features clearly correlated to emotional arousal and concomitant measures of standard physiological signals of the sympathetic activity. The results of this study indicate functional infrared imaging as an alternative, touch less, non invasive method for assessing individual's emotional arousal in psychophysiology.

Combined thermal and laser Doppler imaging in the assessment of cutaneous tissue perfusion.

Infrared thermal imaging permits to non-invasively obtain, throughout bioheat models using a series of thermal images, the cutaneous blood perfusion. Laser Doppler imaging measures blood flow in the very small blood vessels of the microvascular network. In this paper, we compare findings from the two methods on a set of healthy volunteers. Cutaneous blood perfusion values obtained from thermal imaging correlate to those obtained by means of Laser Doppler imaging with the advantage of a better time resolution. Combined imaging of the two modalities may provide a useful tool for monitoring diseases affecting cutaneous tissue and/or microcirculation.

Superimposition of thermal imaging to visual imaging using homography.

InfraRed Thermal Imaging (IR) permits to non-invasively map the skin temperature distribution of the human body. Combining together thermal and visual imaging enriches the informative content of IR images and provides to the physician an anatomically-based and more friendly visualization--on the thermal images--of the presence of possible pathological processes. In this paper we use a homography technique to overlap a thermal image to a visible one. The technique provides an effective pixel-to-pixel correspondences between the two images or their portions.

Penile cutaneous temperature in systemic sclerosis: a thermal imaging study.

Systemic Sclerosis is a connective tissue disorder featuring vascular alterations and an immunological activation leading to a progressive and widespread fibrosis of several organs such as the skin, lung, gastrointestinal tract, heart and kidney. Moreover men with systemic sclerosis (SSc) present an increased risk of developing erectile dysfunction (ED). Recently, we evaluated the extent of penile vascular damage in sclerodermic patients using Duplex ultrasonography. The aim of this paper is to investigate whether penile thermal differences exist between sclerodermic patients and healthy controls. For this reason 10 men with SSc receiving current treatment for their disease, and 10 healthy controls were enrolled; penile thermal properties were assessed through non-contact thermal imaging (functional Infra Red Imaging fIRI); erectile function was evaluated using the sexual health inventory for men (SHIM) questionnaire. The SHIM results confirmed the presence of ED in sclerodermic patients. Baseline penile temperature in patients (32.1 +/- 1.4 degrees C) was lower than in controls (34.1 +/- 0.9 degrees C). Recovery from cooling test was seen to be faster in healthy controls than in patients, both in terms of recovery amplitude (patients 3.75 +/- 2.09 degrees C, controls 9.80 +/- 2.77 degrees C) and amplitude to time constant ratio (patients 1.21 +/- 0.64 degrees C/min, controls 1.96 +/- 0.48 degrees C/min). These results show that penile thermal abnormalities occur in almost all sclerodermic patients. Non-contact thermal imaging not only identifies thermal alterations but also clearly distinguishes between SSc patients and healthy controls and therefore could represent a valuable instrument in identifying early ED in SSc patients.

Functional infrared imaging in medicine: a quantitative diagnostic approach.

The role and the potentialities of high-resolution infrared thermography, combined to bio-heat modelling, have been largely described in the last years in a wide variety of biomedical applications. Quantitative assessment over time of the cutaneous temperature and/or of other biomedical parameters related to the temperature (e.g., cutaneous blood flow, thermal inertia, sympathetic skin response) allows for a better and more complete understanding and description of functional processes involved and/or altered in presence of ailment and interfering with the regular cutaneous thermoregulation. Such an approach to thermal medical imaging requires both new methodologies and tools, like diagnostic paradigms, appropriate software for data analysis and, even, a completely new way to look at data processing. In this paper, some of the studies recently made in our laboratory are presented and described, with the general intent of introducing the reader to these innovative methods to obtain quantitative diagnostic tools based on thermal imaging.

Proton-pump inhibitors and outcome of endoscopic hemostasis in bleeding peptic ulcers: a series of meta-analyses.

OBJECTIVE: To perform meta-analyses of studies on outcome of bleeding ulcers of different proton-pump inhibitors (PPIs) regimens, after stratification of patients by endoscopic stigmata, and analysis of studies with and without endotherapy. METHODS: A total of 35 randomized trials comparing PPIs to placebo and/or H2-receptor antagonists (H2RAs) in 4,843 patients with high-risk endoscopic stigmata were retrieved. Outcomes were rebleeding, surgery, and mortality. RESULTS: Monotherapy with oral or bolus PPIs was superior to placebo and H2RAs in reducing rebleeding in both bleeders and nonbleeders at index endoscopy; the need for surgery was reduced only when compared to H2RAs. In nonbleeders, PPI monotherapy was as effective as a combination of endotherapy with H2RAs. A combination of endotherapy with PPIs was superior to monotherapy in reducing bleeding and surgery, and superior to endotherapy alone in minimizing rebleeding, but not surgery; the benefit was lost when confronted to endotherapy plus H2RAs, whether PPIs were given as infusion or bolus. By pooling data from studies comparing high doses of PPIs as continuous infusion versus regular doses as intermittent bolus, rebleeding, surgery, and mortality were not significantly different. CONCLUSIONS: Combination of endotherapy with either PPIs or H2RAs is indicated for nonbleeding ulcers at endoscopy with the intent to reduce rebleeding and surgery. Its value may extend to bleeding lesions, but current data are scanty. The benefit appears to be independent from route and doses of PPIs, as oral, bolus, or infusional methods are all effective.