Cerebrovascular pattern improved by ozone autohemotherapy: an entropy-based study on multiple sclerosis patients.

Ozone major autohemotherapy is effective in reducing the symptoms of multiple sclerosis (MS) patients, but its effects on brain are still not clear. In this work, we have monitored the changes in the cerebrovascular pattern of MS patients and normal subjects during major ozone autohemotherapy by using near-infrared spectroscopy (NIRS) as functional and vascular technique. NIRS signals are analyzed using a combination of time, time-frequency analysis and nonlinear analysis of intrinsic mode function signals obtained from empirical mode decomposition technique. Our results show that there is an improvement in the cerebrovascular pattern of all subjects indicated by increasing the entropy of the NIRS signals. Hence, we can conclude that the ozone therapy increases the brain metabolism and helps to recover from the lower activity levels which is predominant in MS patients.

Effect of Ocular Movements during Eye Movement Desensitization and Reprocessing (EMDR) Therapy: A Near-Infrared Spectroscopy Study.

INTRODUCTION: Eye Movement Desensitization and Reprocessing (EMDR) is a psychotherapeutic treatment resolving emotional distress caused by traumatic events. With EMDR, information processing is facilitated by eye movements (EM) during the recall of a traumatic memory (RECALL). The aim of this study is to investigate the effects of ocular movements of EMDR on the hemodynamics of the prefrontal cortex (PFC). MATERIAL AND METHODS: Two groups were recruited: a trial group (wEM) received a complete EMDR treatment, whereas a control group (woEM) received a therapy without EM. PFC hemodynamics was monitored by near-infrared spectroscopy during RECALL and during focusing on the worst image of the trauma (pre-RECALL). The parameters of oxy- (oxy-Hb), and deoxy-hemoglobin (deoxy-Hb) were acquired and analyzed in time domain, by calculating the slope within pre-RECALL and RECALL periods, and in the frequency domain, by calculating the mean power of oxy-Hb and deoxy-Hb in the very-low frequency (VLF, 20-40 mHz) and low frequency (LF, 40-140 mHz) bandwidths. We compared pre-RECALL with RECALL periods within subjects, and pre-RECALL and RECALL parameters of wEM with the corresponding of woEM. RESULTS: An effect of group on mean slope of oxy-Hb and deoxy-Hb in pre-RECALL and oxy-Hb in RECALL periods was observed. wEM showed a lower percentage of positive angular coefficients during pre-RECALL with respect to RECALL, on the opposite of woEM. In the frequency domain, wEM had significant difference in oxy-Hb and deoxy-Hb LF of left hemisphere, whereas woEM showed no difference. DISCUSSION AND CONCLUSION: We observed the effect of EM on PFC oxygenation during EMDR, since wEM subjects showed a mean increase of oxy-Hb during RECALL and a decrease during pre-RECALL, as opposed to woEM. Frequency analysis evidenced a reduction of activity of sympathetic nervous system in wEM group during pre-RECALL. Our outcomes revealed a different hemodynamics induced by eye movements in wEM with respect to woEM group.

Empirical mode decomposition analysis of near-infrared spectroscopy muscular signals to assess the effect of physical activity in type 2 diabetic patients.

Type 2 diabetes is a metabolic disorder that may cause major problems to several physiological systems. Exercise has proven to be very effective in the prevention, management and improvement of this pathology in patients. Muscle metabolism is often studied with near-infrared spectroscopy (NIRS), a noninvasive technique that can measure changes in the concentration of oxygenated (O2Hb) and reduced hemoglobin (HHb) of tissues. These NIRS signals are highly non-stationary, non-Gaussian and nonlinear in nature. The empirical mode decomposition (EMD) is used as a nonlinear adaptive model to extract information present in the NIRS signals. NIRS signals acquired from the tibialis anterior muscle of controls and type 2 diabetic patients are processed by EMD to yield three intrinsic mode functions (IMF). The sample entropy (SE), fractal dimension (FD), and Hurst exponent (HE) are computed from these IMFs. Subjects are monitored at the beginning of the study and after one year of a physical training programme. Following the exercise programme, we observed an increase in the SE and FD and a decrease in the HE in all diabetic subjects. Our results show the influence of physical exercise program in improving muscle performance and muscle drive by the central nervous system in the patients. A multivariate analysis of variance performed at the end of the training programme also indicated that the NIRS metabolic patterns of controls and diabetic subjects are more similar than at the beginning of the study. Hence, the proposed EMD technique applied to NIRS signals may be very useful to gain a non-invasive understanding of the neuromuscular and vascular impairment in diabetic subjects.

Chronic cerebrospinal venous insufficiency is not associated with chronic venous disorders: A case-control study.

OBJECTIVES: To evaluate the relationship between chronic cerebrospinal venous insufficiency (CCSVI) and the presence of a Chronic Venous Disorder (CVD). METHOD: We included 55 subjects with CCSVI aged >18 years, and 186 controls without CCSVI. Each subject was evaluated with color Doppler sonography in accordance with Zamboni's five criteria, examined by two neurologists and interviewed with an ad-hoc designed form. The neurologists and the sonographers were mutually blinded. CVD were classified according to CEAP. RESULTS: Mean age was 42 years (SD = 9) in cases and 43 years (10) in controls (p = ns). The odds ratios in subjects CCSVI were 0.6 (0.2-2.2) for CEAP 1, 0.9 (0.2-4.5) for CEAP 2, and 1.0 (0.6-1.9) for family history of varicose veins. The prevalence of CVD and, family history of varicose veins, was similar between cases and controls for each Zamboni criterion. CONCLUSIONS: We found no association of CCSVI with the presence of CVD or family history of varicose veins.

A reliability study of colour-Doppler sonography for the diagnosis of chronic cerebrospinal venous insufficiency shows low inter-rater agreement.

OBJECTIVE: Chronic cerebrospinal venous insufficiency (CCSVI) has been extremely variable, associated with multiple sclerosis in colour-Doppler sonographic studies. We aimed to evaluate inter-rater agreement in a colour-Doppler sonography venous examination. DESIGN: Inter-rater agreement study. SETTING: First-referral multiple sclerosis centre. PARTICIPANTS: 38 patients with multiple sclerosis and 55 age-matched (±5 years) controls. INTERVENTION: Sonography was carried out in accordance with Zamboni's five criteria by eight sonographers with different expertise, blinded to the status of cases and controls. Each participant was evaluated by two operators. PRIMARY AND SECONDARY OUTCOME MEASURES: Inter-rater agreement was measured through the κ statistics and the intraclass correlation coefficient. RESULTS: The agreement was no higher than chance for criterion 2-reflux in the deep cerebral veins (κ=-0.02) and criterion 4-flow not Doppler detectable in one or both the internal jugular veins (IJVs) or vertebral veins (VVs; -0.09). It was substantially low for criterion 1-reflux in the IJVs and/or VVs (0.29), criterion 3-IJV stenosis or malformations (0.23) and criterion 5-absence of IJV diameter increase when passing from the sitting to the supine position (0.22). The κ value for CCSVI as a whole was 0.20 (95% confidence limit -0.01 to 0.42). Intraclass correlation coefficients for the measure of cross-sectional area ranged from 0.05 to 0.25. Inter-rater agreement was low for CCSVI experts (κ=0.24; -0.11 to 0.59) and non-experts (0.20; -0.33 to 0.73); neurologists (0.21; -0.06 to 0.47) and non-neurologists (0.18; -0.20 to 0.56); cases (0.19; -0.14 to 0.52) and controls (0.21; -0.08 to 0.49). Zamboni-trained neurosonographers ascertained CCSVI more frequently than the non-trained neurosonographers. CONCLUSIONS: Agreement was unsatisfactory for the diagnosis of CCSVI as a whole, for each of its five criteria and according to the different subgroups. Standardisation of the method is urgently needed prior to its further application in studies of patients with multiple sclerosis or other neurological diseases.

Entropy analysis of muscular near-infrared spectroscopy (NIRS) signals during exercise programme of type 2 diabetic patients: quantitative assessment of muscle metabolic pattern.

Diabetes mellitus (DM) is a metabolic disorder that is widely rampant throughout the world population these days. The uncontrolled DM may lead to complications of eye, heart, kidney and nerves. The most common type of diabetes is the type 2 diabetes or insulin-resistant DM. Near-infrared spectroscopy (NIRS) technology is widely used in non-invasive monitoring of physiological signals. Three types of NIRS signals are used in this work: (i) variation in the oxygenated haemoglobin (O2Hb) concentration, (ii) deoxygenated haemoglobin (HHb), and (iii) ratio of oxygenated over the sum of the oxygenated and deoxygenated haemoglobin which is defined as: tissue oxygenation index (TOI) to analyze the effect of exercise on diabetes subjects. The NIRS signal has the characteristics of non-linearity and non-stationarity. Hence, the very small changes in this time series can be efficiently extracted using higher order statistics (HOS) method. Hence, in this work, we have used sample and HOS entropies to analyze these NIRS signals. These computer aided techniques will assist the clinicians to diagnose and monitor the health accurately and easily without any inter or intra observer variability. Results showed that after a one-year of physical exercise programme, all diabetic subjects increased the sample entropy of the NIRS signals, thus revealing a better muscle performance and an improved recruitment by the central nervous system. Moreover, after one year of physical therapy, diabetic subjects showed a NIRS muscular metabolic pattern that was not distinguished from that of controls. We believe that sample and bispectral entropy analysis is need when the aim is to compare the inner structure of the NIRS signals during muscle contraction, particularly when dealing with neuromuscular impairments.

Chronic cerebrospinal venous insufficiency is not associated with multiple sclerosis and its severity: a blind-verified study.

BACKGROUND: Chronic Cerebrospinal Venous Insufficiency (CCSVI) has been associated with multiple sclerosis (MS) with a risk ranging from as high as two-hundred-fold to a protective effect. However, not all studies were blinded, and the efficacy of blinding was never assessed. OBJECTIVE: To evaluate the association of CCSVI with MS in a cross-sectional blinded study and look for any association of CCSVI with the severity of MS. METHODOLOGY/PRINCIPAL FINDINGS: The Echo-color Doppler examination was carried out in accordance with Zamboni's five criteria in 68 consecutive MS patients and 68 healthy controls, matched by gender and age (±5 years). Four experienced neurosonologists, blinded to the status of cases and controls, performed the study and were then asked to guess the status (case or control) of each participant. The number of positive CCSVI criteria was similar in the two groups. CCSVI, defined as the presence of two or more criteria, was detected in 21 cases (30.9%) and 23 controls (33.8%), with an OR of 0.9 (95%CL = 0.4-1.8, p = 0.71). The prevalence of CCSVI was related to age in cases (OR increasing from 0.2 to 1.4), but not in controls. CCSVI positive (N = 21) and negative (N = 47) MS patients were similar in clinical type, age at disease onset, disability, and fatigue. Disease duration was longer (16.5±9.8 years) in CCSVI positive than negative patients (11.5±7.4; p = 0.04). The operators correctly guessed 34/68 cases (50%) and 45/68 controls (66%) (p = 0.06), indicating a different success of blinding. CONCLUSIONS/SIGNIFICANCE: CCSVI was not associated with MS itself, nor its severity. We cannot rule out the possibility that CCSVI is a consequence of MS or of aging. Blinding of sonographers is a key point in studying CCSVI and its verification should be a requisite of future studies.

Carotid artery recognition system: a comparison of three automated paradigms for ultrasound images.

PURPOSE: The development of completely automated techniques for arterial wall segmentation and intima-media thickness measurement requires the recognition of the artery in the image frame. Conceptually, automated techniques can be thought of as the combination of two cascaded stages: artery recognition and wall segmentation. In this paper, the authors show three carotid artery recognition systems (CARS) that are fully automated. METHODS: The first technique is based on a first-order derivative Gaussian edge analysis (CARSgd). The second method is based on an integrated approach (CARSia) that combines image feature extraction, fitting, and classification. The third strategy is based on signal analysis (CARSsa). The output of all the three paradigms provide tracing of the far adventitial (AD(F)). The authors validated CARSgd, CARSia, and CARSsa on a dataset of 365 longitudinal B-Mode carotid images, acquired by different sonographers. Performance evaluation of the carotid recognition process was done in three ways: (1) visual inspection by experts; (2) by measuring the Hausdorff distance (HD) between the automatic far adventitial (AD(F)) and the manually traced AD(F), and (3) by measuring the HD between AD(F) and the lumen-intima (GT(LI)) and media-adventitia (GT(MA)) borders of the arterial walls. RESULTS: The average HD between AD(F) and the manual AD(F) was 1.53 ± 1.51 mm for CARSgd, 1.82 ± 3.08 mm for CARSia, and 2.56 ± 2.89 mm for CARSsa. The average HD between GT(LI) and AD(F) for CARSgd, CARSia, and CARSsa were 2.16 ± 1.16 mm, 2.71 ± 2.89 mm, and 2.66 ± 1.52 mm, respectively. The average HD between AD(F) and GT(MA) for CARSgd, CARSia, and CARSsa were 1.54 ± 1.19 mm, 1.86 ± 2.66 mm, and 1.95 ± 1.64 mm, respectively. Considering a maximum distance of 50 pixels (about 3 mm), CARSgd showed an identification accuracy of 100%, CARSia of 92%, and CARSsa of 96%. These identification accuracies were confirmed by visual inspection. All the three systems work on MATLAB, Windows OS, and on a PC based cross platform medical application written in Java called ATHEROEDGE™ with 1 s per image. CONCLUSIONS: CARSgd showed very accurate AD(F) profiles coupled with a low computational burden and without the need for specific tuning. It can be thought of as a reference technique for carotid localization, to be used in automated intima-media thickness measurement strategies.

Automated carotid artery intima layer regional segmentation.

Evaluation of the carotid artery wall is essential for the assessment of a patient's cardiovascular risk or for the diagnosis of cardiovascular pathologies. This paper presents a new, completely user-independent algorithm called carotid artery intima layer regional segmentation (CAILRS, a class of AtheroEdge™ systems), which automatically segments the intima layer of the far wall of the carotid ultrasound artery based on mean shift classification applied to the far wall. Further, the system extracts the lumen-intima and media-adventitia borders in the far wall of the carotid artery. Our new system is characterized and validated by comparing CAILRS borders with the manual tracings carried out by experts. The new technique is also benchmarked with a semi-automatic technique based on a first-order absolute moment edge operator (FOAM) and compared to our previous edge-based automated methods such as CALEX (Molinari et al 2010 J. Ultrasound Med. 29 399-418, 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CULEX (Delsanto et al 2007 IEEE Trans. Instrum. Meas. 56 1265-74, Molinari et al 2010 IEEE Trans. Ultrason. Ferroelectr. Freq. Control 57 1112-24), CALSFOAM (Molinari et al Int. Angiol. (at press)), and CAUDLES-EF (Molinari et al J. Digit. Imaging (at press)). Our multi-institutional database consisted of 300 longitudinal B-mode carotid images. In comparison to semi-automated FOAM, CAILRS showed the IMT bias of -0.035 ± 0.186 mm while FOAM showed -0.016 ± 0.258 mm. Our IMT was slightly underestimated with respect to the ground truth IMT, but showed uniform behavior over the entire database. CAILRS outperformed all the four previous automated methods. The system's figure of merit was 95.6%, which was lower than that of the semi-automated method (98%), but higher than that of the other automated techniques.

Joint Metabonomic and Instrumental Analysis for the Classification of Migraine Patients with 677-MTHFR Mutations.

Migraine is a neurological disorder that correlates with an increased risk of cerebrovascular lesions. Genetic mutations of the MTHFR gene are correlated to migraine and to the increased risk of artery pathologies. Also, migraine patients show altered hematochemical parameters, linked to an impaired platelet aggregation mechanism. Hence, the vascular assessment of migraineurs is of primary importance.Transcranial Doppler sonography (TCD) is used to measure cerebral blood flow velocity (CBFV) and vasomotor reactivity (by an index measured during breath-holding - BHI). Aim of this study was the metabolic profiling of migraine subjects with T/T677-MTHFR and C/T677-MTHFR mutations and its correlation with CBFV and BHI.Metabonomic multidimensional techniques were used to describe and cluster subjects. Fifty women suffering from migraine (age: 18-64; 21 with aura) underwent TCD examination, hematochemical blood analysis, Born test, and genetic tests for MTHFR mutation. Fourteen (7 with aura) had T/T677, 18 (8 with aura) had C/T677, and 18 (6 with aura) had no mutation. The total number of variables was 24.Unsupervised and supervised techniques_showed the correlation between CBFV and BHI with mutation. Discriminant analysis allowed for classifying the subjects with 95.9% sensitivity and 89.0% specificity. Aura was not correlated to mutation or variations of instrumental data.Our study showed that metabonomics could be effectively applied in clinical problems to show the overall correlation structure of complex systems in pathology. Specifically, our results confirmed the importance of TCD in the metabolic profiling and follow-up of migraine patients.

Perceptive aspects of visual aura.

Visual aura is the most common feature associated with migraine, though it can occur separately. In both cases it often represents a dramatic event, especially for patients who experience it for the first time. Besides, its subjective characteristics may illuminate on the functional architecture of the visual cortex. Repetitive events of migraine and visual aura have been suggested to affect the visual system in the long run, both on the cortical and precortical level. In effect, objective investigation of visual functions in patients support the idea that a selective damage does occur, so that more attention to visual examination seems to be justified. In this paper, subjective and psychophysical aspects of visual aura are examined, lastly highlighting and discussing the interesting correlations found between this condition and normal-tension glaucoma.

Spectral changes of near-infrared spectroscopy signals in migraineurs with aura reveal an impaired carbon dioxide-regulatory mechanism.

Subjects suffering from migraine with aura (MwA) present an altered cerebral autoregulation during migraine attacks. It is still unclear whether MwA sufferers present a normal autoregulation during attack-free periods. In this study, we characterized cerebral autoregulation in the frequency domain by analyzing the spontaneous oscillations superimposed on the cerebral hemodynamic signals, as detected by near-infrared spectroscopy (NIRS). Ten healthy women (age: 38.4 +/- 9.5 years) and ten women suffering from MwA (age: 35.2 +/- 10.5 years) underwent NIRS recording in resting conditions and during breath-holding (BH). Being the NIRS signals during BH nonstationary, we used the Choi-Williams time-frequency distribution to perform spectral analysis. We considered 256 s of signals and quantified the variation in the power of the very-low frequencies (VLF: 20-40 mHz) and of the low frequencies (LF: 40-140 mHz) as response to BH. Results showed that BH increases the power in the LF band both in healthy and MwA subjects. Considering the signal of the deoxygenated hemoglobin, the average power increase in the LF band was equal to 20% +/- 15.4% for the healthy group and significantly lower, 4.8% +/- 8.3%, in the MwA group (Student's t test, P < 0.02). No significant difference was observed in the VLF band or in the oxygenated hemoglobin signal power variations of the LF and VLF bands. The resulting data reveal a possible impairment in the carbon dioxide-regulatory mechanism in MwA subjects.

The diagnostic iter of patent foramen ovale in migraine patients: an update.

Patent foramen ovale (PFO) is a frequent finding in migraine patients. The standard technique for PFO diagnosis is actually trans-oesophageal echocardiography (TEE). It requires the injection of a contrast agent unable to pass the pulmonary filter; hence, it is possible to detect a right-to-left shunt by observing the presence of the contrast medium in the cardiac left compartment. The transcranial Doppler (TCD) device accurately measures the blood flow velocities in different cerebral arteries. It can record microembolic signals (MES) backscattered by microbubbles travelling in the cerebral circulation, and distinguish cardiac shunts from pulmonary shunts. The number of MES is correlated to the entity of the shunt. The near-infrared spectroscopy (NIRS) technique tracks the changes in the concentration of oxygenated and reduced haemoglobin in the brain tissue. PFO is revealed by an alteration of the normal vasoreactivity pattern of the subject during functional stimuli. Magnetic resonance imaging (MRI) provides, at the same time, detailed anatomical information and functional measurements. MRI dynamic perfusion sequences can be used to reliably detect PFO either by visual assessment or by signal-time curves in the pulmonary artery and in the left atrium. A good correlation between TEE and MRI grading scores has been demonstrated, even though the interindividual variability of performing the Valsalva manoeuvre could greatly reduce the sensitivity of the method. Further prospective studies are needed to confirm the PFO MRI grading and to assess the sensitivity and specificity of the method.

Patent foramen ovale detected by near-infrared spectroscopy in patients suffering from migraine with aura.

There is an increased prevalence of patent foramen ovale (PFO) in women with migraine with aura (MwA) compared to controls, but the role of PFO in triggering aura is still debated. The aim of this study was to test a group of women suffering from MwA with near-infrared spectroscopy (NIRS), to assess the NIRS capability of discriminating between subjects with and without PFO. Eighty-eight MwA patients (mean age 37.4+/-10.7 years, range 16-62 years) underwent NIRS measurement of the cerebral variations of the oxygenated (O2Hb) and reduced haemoglobin (HHb) during breath-holding. The prevalence of O2Hb vs. HHb was used to assess the presence of PFO. As a gold standard, the presence of PFO was assessed by transcranial Doppler sonography (TCD). At the TCD analysis 48 patients (55%) showed PFOs, 32 of which were permanent. NIRS correctly detected 36 subjects out of 40 without PFO, and 38 subjects out of 48 having PFO: sensitivity was 79%; specificity was 90%. All the false negatives were permanent shunts. MwA patients with PFO showed a delayed increase in the O2Hb concentration and a reduced oxygenation with respect to subjects without PFO. NIRS is effective in identifying the presence of PFO in a MwA population, but TCD achieves better diagnostic performances. The NIRS provides additional information about the cerebral vasoreactivity and highlights substantial differences between patients with latent and permanent shunts that warrant further studies.

Accurate and automatic carotid plaque characterization in contrast enhanced 2-d ultrasound images.

The carotid plaques characterization is essential to decide about the possibility of surgical intervention (endarterectomy/stenting) on the patient. Soft and unstable plaques represent a major risk for the patient, as they are correlated with an augmented probability of brain infarction and emboli generation. Hence, the minimally-invasive characterization especially of this type of carotid plaques is crucial in clinical practice. This paper presents an integrated system for the completely user-independent carotid plaque segmentation and characterization, based on ultrasound 2-D images. We show that using a ultrasound contrast agent, it is possible to segment also echolucent plaques with a percentage of misclassified pixels equal to 8%. After segmentation, the enhanced image is used to perform tissue characterization. We tested our system on 5 echolucent plaques and on 5 fibrous/stable plaques, showing that our system is capable of an accurate carotid wall segmentation and proper quantification of the percentages of blood, fat, calcium and fibrous tissue constituting the plaque. The system is very promising and it is being used in a neurology unit on patients already indicated for endarterectomy, with the purpose of correlating its output with histology.

Relationship between oxygen supply and cerebral blood flow assessed by transcranial Doppler and near-infrared spectroscopy in healthy subjects during breath-holding.

BACKGROUND: Breath-holding (BH) is a suitable method for inducing cerebral vasomotor reactivity (VMR). The assessment of VMR is of clinical importance for the early detection of risk conditions and for the follow-up of disabled patients. Transcranial Doppler ultrasonography (TCD) is used to measure cerebral blood flow velocity (CBFV) during BH, whereas near-infrared spectroscopy (NIRS) measures the concentrations of the oxygenated (O2Hb) and reduced (CO2Hb) hemoglobin. The two techniques provide circulatory and functional-related parameters. The aim of the study is the analysis of the relationship between oxygen supply and CBFV as detected by TCD and NIRS in healthy subjects performing BH. METHODS: 20 healthy subjects (15 males and 5 females, age 33 +/- 4.5 years) underwent TCD and NIRS examination during voluntary breath-holding. VMR was quantified by means of the breath-holding index (BHI). We evaluated the BHI based on mean CBFV, O(2)Hb and CO(2)Hb concentrations, relating the baseline to post-stimulus values. To quantify VMR we also computed the slope of the linear regression line of the concentration signals during BH. From the NIRS signals we also derived the bidimensional representation of VMR, plotting the instantaneous O(2)Hb concentration vs the CO(2)Hb concentration during the BH phase. Two subjects, a 30 years old current smoker female and a 63 years old male with a ischemic stroke event at the left middle cerebral artery, were tested as case studies. RESULTS: The BHI for the CBFV was equal to 1.28 +/- 0.71 %/s, the BHI for the O(2)Hb to 0.055 +/- 0.037 micromol/l/s and the BHI for CO2Hb to 0.0006 +/- 0.0019 micromol/l/s, the O2Hb slope was equal to 0.15 +/- 0.09 micromol/l/s and the CO(2)Hb slope to 0.09 +/- 0.04 micromol/l/s. There was a positive correlation between the CBFV and the O(2)Hb increments during BH (r = 0.865). The bidimensional VMR pattern shows common features among healthy subjects that are lost in the control studies. CONCLUSION: We show that healthy subjects present a common VMR pattern when counteracting cerebral blood flow perturbations induced by voluntary BH. The proposed methodology allows for the monitoring of changes in the VMR pattern, hence it could be used for assessing the efficacy of neurorehabilitation protocols.

User-independent plaque characterization and accurate IMT measurement of carotid artery wall using ultrasound.

Non-invasive plaque characterization of the carotid wall is crucial for the early assessment of pathology, as well as for the monitoring of the progression of a degenerative phenomenon. Specifically, in clinical practice the carotid wall status is assessed by means of B-Mode ultrasound scans. We recently implemented an algorithm for the segmentation of the common tract of the carotid wall using ultrasound relative to healthy subjects. This paper presents a superior strategy for plaque characterization, which accurately determines both echolucent-type II and echogenic plaques in pathologic subjects. We preserve both user-independence and pixel fuzziness in our approach, thereby designing an accurate intima-media thickness (IMT). Our database consists of 20 subjects comprising of normal, stable (echogenic) and unstable (echolucent) plaques. In this database of 45 images, we demonstrate our performance with respect to the gold standard tracings to an accuracy determined as normalized error to be about 8%. The results are very promising and this algorithm is being integrated into clinical setup for automatic pathologic carotid wall analysis.

CULEX-completely user-independent layers extraction: ultrasonic carotid artery images segmentation.

The analysis of the carotid wall is of paramount importance in clinical practice. In fact, the intima-media thickness is a risk index for some of the most severe acute cerebrovascular pathologies; hence, the need for an accurate segmentation of the different layers of the carotid artery. In the past ten years, a wide variety of algorithms for the carotid tunica segmentation have been proposed, but they require a certain degree of user interaction. In this paper we propose a novel approach to the completely user-independent segmentation of the carotid artery wall. Our algorithm has been designed for the extraction of the intima and media layers of the distal carotid wall, based on ultrasonic B-Mode images. We evaluated the performance of the algorithm on a set of 63 images and compared the automatic segmentation to that traced by a trained operator. We obtained a mean error lower than 1.3 pixel both on the intima and media layers, which is comparable to that obtained by means of operator dependent techniques.