Diagnosis Yield and Safety of Surgical Biopsy in Interstitial Lung Diseases: A Prospective Study.

BACKGROUND: Surgical lung biopsy is essential in the diagnostic algorithm of interstitial lung disease (ILD) of unknown cause. Safety concerns have been recently reiterated. This study prospectively assessed the yield of diagnosis and safety of video-assisted thoracoscopic surgical lung biopsy (VATS-LB) for ILD diagnosis. METHODS: This prospective study, conducted in 6 ILD-referral Paris hospitals, included 103 patients with ILD. VATS-LB was proposed after initial multidisciplinary discussion. A final diagnosis was made after the procedure, during a second multidisciplinary discussion. The main outcome was to determine the final diagnoses and their proportion after VATS-LB. Other outcomes were the percentage of change in diagnosis and treatment propositions after VATS-LB and adverse events during 3 months after the operation, postoperative pulmonary function, quality of life, and pain. RESULTS: A definite diagnosis was reached in 87 patients (84.4%), and 16 remained unclassifiable (15.6%). After VATS-LB, the hypothesized diagnosis changed in 65 patients (63.1%) and treatment changed in 41 patients (39.8%). One patient died of acute exacerbation. In-hospital complications were predicted by a shorter preoperative 6-minute walking test distance and by forced vital capacity lower than 77%. Postoperative quality of life was not modified at 3 months, whereas forced vital capacity decreased slightly. Postoperative neuropathic pain was revealed in 5% of patients at 1 month and in 2% at 3 months. CONCLUSIONS: VATS-LB dramatically changed preoperative hypothetical diagnoses and treatment in ILD of unknown cause, with good patient survival in ILD referral centers.

Multispectral measurement of scattering-angular light distribution in apple skin and flesh samples.

Knowledge of the optical properties of apple tissues such as skin and flesh is essential to better understand the light-tissue interaction process and to apply optical methods for apple quality inspection. This work aimed at estimating the anisotropy factor of thin skin and flesh samples extracted from three apple cultivars. The scattering-angular light distribution in each tissue sample was measured at four wavelengths (λ=633, 763, 784, and 852 nm), by means of a goniometer setup. Based on the recorded angular intensity I(θ,λ), the effective anisotropy factor geff of each tissue type was first estimated using the mean statistics applied to the random variable cos θ. Next, the measured data were fitted with three predefined and modified phase functions-Henyey-Greenstein (pMHG), Gegenbauer kernel (pMGK), and Mie (pMie)-in order to retrieve the corresponding anisotropy factors gMHG, gMGK, and gMMie. Typically, the anisotropy factors of skin and flesh amount to 0.6-0.8 in the above-mentioned wavelength range.

Depth sensitivity analysis of functional near-infrared spectroscopy measurement using three-dimensional Monte Carlo modelling-based magnetic resonance imaging.

Theoretical analysis of spatial distribution of near-infrared light propagation in head tissues is very important in brain function measurement, since it is impossible to measure the effective optical path length of the detected signal or the effect of optical fibre arrangement on the regions of measurement or its sensitivity. In this study a realistic head model generated from structure data from magnetic resonance imaging (MRI) was introduced into a three-dimensional Monte Carlo code and the sensitivity of functional near-infrared measurement was analysed. The effects of the distance between source and detector, and of the optical properties of the probed tissues, on the sensitivity of the optical measurement to deep layers of the adult head were investigated. The spatial sensitivity profiles of photons in the head, the so-called banana shape, and the partial mean optical path lengths in the skin-scalp and brain tissues were calculated, so that the contribution of different parts of the head to near-infrared spectroscopy signals could be examined. It was shown that the signal detected in brain function measurements was greatly affected by the heterogeneity of the head tissue and its scattering properties, particularly for the shorter interfibre distances.

In vivo comparison between the principal components analysis and the Karhunen-Loève transform as methods used for the de-noising of laser Doppler reactive hyperemia signals.

This contribution shows the comparison of two methods, the principal components analysis and the Karhunen-Loève transform. Indeed, reactive hyperemia signals obtained with laser Doppler flowmetry are currently used to diagnose peripheral arterial occlusive diseases (PAOD), but they are not noise-free. De-noising of such signals could lead to an improved diagnosis. For this purpose, the principal components analysis and the Karhunen-Loève transform were applied to signals acquired on PAOD and healthy subjects. Our main purpose was to have the two methods undergo a comparison that reveals the capacity of each method to interpret the characteristics of the signals used to make diagnosis. The results show that the use of the Karhunen-Loève transform method is more justified than the principal components analysis whenever we want to reduce the dimensional space of the set of initial data and still preserve the quantitative and relative proportions of the original variances associated to those data representing the laser Doppler flowmetry signal before and after its reconstruction. However, the principal components analysis method is more justified when one or several of the initial data present variances either too insignificant or too important in comparison with the other data.

Effects of residual fluorescence on time-resolved signals simulated with the finite element method in biological tissues.

A computational model based on finite element method is derived to examine how the simulated time-dependent signals are related to the presence of residual fluorescence in biological media surrounding a fluorescent object. We apply a subtraction technique on recorded data when imperfect uptake of fluorescing agent into the tumor is considered. We show the limits of the subtracting method for low target: background fluorescent absorption contrast by extracting the time to reach the half maximum and analyzing the maximum of the time-resolved signals versus target depth.

S-transform applied to laser Doppler flowmetry reactive hyperemia signals.

Laser Doppler flowmetry signals give information about many physiological activities of the cardiovascular system. The activities manifest themselves in rhythmic cycles. In order to explore these activities during the reactive hyperemia phenomenon, a novel time-frequency method, called the S-transform, based on a scalable Gaussian wavelet, is applied. The goal is to have a deeper understanding of reactive hyperemia. This paper focuses on the evaluation of the different activities between a rest signal and an hyperemia signal, both acquired simultaneously on the two forearms of healthy subjects. The results show that after the release of the occlusion, the myogenic, neurogenic, and endothelial related activities clearly increase on the forearm where the occlusion took place. Then, they return progressively to their basal level. However, on the rest forearm, no increase is noted for the three activities. The mechanisms that take place during reactive hyperemia are, therefore, local. The S-transform proves to be a suited time-frequency method, in order to analyze laser Doppler signal underlying mechanisms.

Detection of heterogeneities embedded within a turbid slab media using time- and frequency-domain methods: application to the mammography.

During the last decade, several methods have been devoted to the detection and imaging of tumor-like objects embedded in turbid slab media. Optical methods are broadly investigated as potential non-invasive medical diagnosis used for the detection of tumors. In this paper, we model the photon migration due to a pulsed source laser, through a multiple scattering slab to locate and characterize heterogeneities of different optical properties. The time-dependent diffusion equation is used and solved by means of a finite element model, taking into account air-tissue boundary conditions. The transmitted time-spectra associated to their Fast Fourier Transforms are used to detect embedded objects within diffusive slab media. We show that for an inclusion of identical scattering coefficient to the surrounding medium, the phase shift increases as the absorption coefficient of the inclusion is increased. For a homogeneous absorption, the phase shift is very sensitive to local variations in scattering properties. We then compare these results with those reported by other workers and conclude that the computational model allows the lateral detection of these inclusions, so it should be possible to enhance the detection of a malignant tumor surrounded by the healthy breast tissue.

Characteristics of tobacco withdrawal in pregnant women.

OBJECTIVE: To describe the management of tobacco withdrawal in pregnant women. STUDY DESIGN: The questionnaire-based, descriptive survey included 979 post-partum women. The variables analysed included the characteristics of the mother and neonate at delivery, her smoking habits, her level of exposure to passive smoking, and the barriers to giving up smoking. The chi square test was used to analyse qualitative variables and the Students t-test for quantitative variables. RESULTS: 76% of women who smoked at the start of pregnancy said that they had been asked about their tobacco consumption. However, only 16% had been asked by a clinician or midwife about their attempts to stop smoking. Seven percent were offered a specialised consultation, but only one-third attended. Seventy-six percent of women who failed to stop smoking during pregnancy had a partner who smoked compared with 63% of women who gave up. Dependency and stress during pregnancy also were lower for women who stopped smoking. CONCLUSIONS: Healthcare professionals seems to offer only rudimentary care. Simple strategies to help women give up smoking are required. The partner is an important target, especially if he can be persuaded to give up at the same time.

Improved localization of hidden fluorescent objects in highly scattering slab media based on a two-way transmittance determination.

We present a novel procedure for localizing fluorescing-tagged objects embedded in turbid slab media from fluorescent intensity profiles acquired along a surface of interest. Using a numerical model based on a finite element code, we firstly develop a method devoted to lateral detection by varying the laser source position along one face of the tissue slab. Next, we mainly demonstrate the possibility to accurately assess the depth location by alternately changing the position of the source and the detector at the both sides of the slab. The dimensionless depth indicator derived from this procedure remains independent, over a wide range, on both the optical properties of the host tissue and the probe concentration. The overall findings validate the method in situations involving moderate size object-like tumors tagged with a new smart contrast agent (Cy 5.5) that offers high tumor-to-background contrast and great interest in early cancer diagnostic.

Description of tobacco addiction in pregnant women.

OBJECTIVE: To compare the characteristics of a group of pregnant women who smoked until delivery with women who gave up smoking during pregnancy. STUDY DESIGN: Questionnaire-based, descriptive study of 979 pregnant women in four regions of France. The variables analysed included the characteristics of the mother and neonate at delivery, the smoking habits of the mother before and during pregnancy, the perception of risk linked to smoking, and the reasons for giving up smoking. RESULTS: Eighteen percent of women smoked until delivery. Fifty-five percent of women gave up smoking during pregnancy, usually in the first trimester. Women who failed to give up smoking were more disadvantaged psychosocially and were more likely to live alone. There was a higher level of dependency among women who failed to give up smoking and a lower perception of risk to the foetus. Among the women who had tried to reduce their tobacco consumption without success, 6% stated that they had been motivated by medical information compared to 28% of women who succeeded in stopping smoking. CONCLUSIONS: Despite the risks associated with smoking the number of pregnant women who smoke until delivery remains high. Knowledge of the psychosocial profile and degree of dependency of these patients is an important step to managing this problem.

Spectral components of laser Doppler flowmetry signals recorded in healthy and type 1 diabetic subjects at rest and during a local and progressive cutaneous pressure application: scalogram analyses.

A significant transient increase in laser Doppler flowmetry (LDF) signals is observed in response to a local and progressive cutaneous pressure application in healthy subjects. This reflex may be impaired in diabetic patients. The work presents a signal processing providing the clarification of this phenomenon. Scalogram analyses of LDF signals recorded at rest and during a local and progressive cutaneous pressure application are performed on healthy and type 1 diabetic subjects. Three frequency bands, corresponding to myogenic, neurogenic and endothelial related metabolic activities, are studied. The results show that, at rest, the scalogram energy of each frequency band is significantly lower for diabetic patients than for healthy subjects, but the scalogram relative energies do not show any statistical difference between the two groups. Moreover, the neurogenic and endothelial related metabolic activities are significantly higher during the progressive pressure than at rest, in healthy and diabetic subjects. However, the relative contribution of the endothelial related metabolic activity is significantly higher during the progressive pressure than at rest, in the interval 200-400 s following the beginning of the pressure application, but only for healthy subjects. These results may improve knowledge on cutaneous microvascular responses to injuries or local pressures initiating diabetic complications.

Time-frequency analysis of laser Doppler flowmetry signals recorded in response to a progressive pressure applied locally on anaesthetized healthy rats.

The laser Doppler flowmetry technique has recently been used to report a significant transient increase of the cutaneous blood flow signal, in response to a local non-noxious pressure applied progressively on the skin of both healthy humans and rats. This phenomenon is not entirely understood yet. In the present work, a time-frequency analysis is applied to signals recorded on anaesthetized healthy rats, at rest and during a cutaneous pressure-induced vasodilation (PIV). The comparison, at rest and during PIV, of the scalogram relative energies and scalogram relative amplitudes in five bands, corresponding to five characteristic frequencies, shows an increased contribution for the endothelial related metabolic activity in PIV signals, till 400 s after the beginning of the progressive pressure application. The other subsystems (heart, respiration, myogenic and neurogenic activities) contribute relatively less during PIV than at rest. The differences are statistically significant for all the relative activities in the interval 0-200 s following the beginning of the pressure. These results and others obtained on patients, such as diabetics, could increase the understanding of some cutaneous pathologies involved in various neurological diseases and in the pathophysiology of decubitus ulcers.

Signal processing methodology to study the cutaneous vasodilator response to a local external pressure application detected by laser Doppler flowmetry.

The existence of a cutaneous pressure-induced vasodilation (PIV) has recently been reported. This paper proposes a signal processing methodology to improve PIV knowledge. Temporal variations of laser Doppler signals rhythmic activities are first analyzed on anesthetized rats. The results lead to a method that provides a better PIV understanding.

Wavelet de-noising of laser Doppler reactive hyperemia signals to diagnose peripheral arterial occlusive diseases.

In order to improve peripheral arterial occlusive diseases (PAOD) diagnoses, five de-noising algorithms based on a multiresolution analysis computed with wavelets are applied on reactive hyperemia signals obtained with the laser Doppler flowmetry technique. Results are presented on recordings acquired on patients suffering from PAOD and on healthy subjects.