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Measuring muscle fatigue and resistance to fatigue is a topical theme in many clinical research studies. Multi-domain approaches, including electromyography (EMG), are employed to measure fatigue in rehabilitation contexts. In particular, spectral features, such as the reduction in the median frequency, are accepted biomarkers to detect muscle fatigue conditions. However, applications of fatigue detection in clinical scenarios are still limited and with margin for improvement. One of the potential applications of such methodology in clinics concerns the evaluation of the rehabilitation after hip fracture. In this work, 20 inpatients, in the acute phase after hip fracture surgery and with lower limb weakness, performed isometric contractions with their healthy lower limb (quadriceps muscle) and their resistance to fatigue before and after 2 weeks of rehabilitation program was measured. Multi-channel EMG and Maximum Voluntary Contractions (MVC, force) were recorded on five muscle heads. We found that, after performing the same number of repetitions (repetitions pre-treatment: 19.7 ± 1.34; repetitions post-treatment: 19.9 ± 0.36; p = 0.223), MVC improved (MVC pre-treatment: 278 ± 112 N; MVC post-treatment: 322 ± 88 N; p = 0.015) after rehabilitation for most of the patients and fatigue did not change. These results suggest that higher force exertion was performed after rehabilitation, with the same level of fatigue (fatigued muscles pre-treatment: 1.40 ± 1.70; fatigued muscles post-treatment: 1.15 ± 1.59; p = 0.175) after. Results are discussed addressing the potential of multifactorial instrumental assessments for describing patients’ status and provide data for clinical decision making.

Significance: Tissue-like solid phantoms with identical optical properties, known within tolerant uncertainty, are of crucial importance in diffuse optics for instrumentation assessment, interlaboratory comparison studies, industrial standards, and multicentric clinical trials. Aim: The reproducibility in fabrication of homogeneous solid phantoms is focused based on spectra measurements by instrument comparisons grounded on the time-resolved diffuse optics. Approach: Epoxy-resin and silicone phantoms are considered as matrices and both employ three different instruments for time-resolved diffuse spectroscopy within the spectral range of 540 to 1100 nm. In particular, we fabricated two batches of five phantoms each in epoxy resin and silicone. Then, we evaluated the intra- and interbatch variability with respect to the instrument precision, by considering the coefficient of variation (CV) of absorption and reduced scattering coefficients. Results: We observed a similar precision for the three instruments, within 2% for repeated measurements on the same phantom. For epoxy-resin phantoms, the intra- and the interbatch variability reached the instrument precision limit, demonstrating a very good phantom reproducibility. For the silicone phantoms, we observed larger values for intra- and interbatch variability. In particular, at worst, for reduced scattering coefficient interbatch CV was about 5%. Conclusions: Results suggest that the fabrication of solid phantoms, especially considering epoxy-resin matrix, is highly reproducible, even if they come from different batch fabrications and are measured using different instruments.

The original version of this Article contained errors in references 3, 4, 25, 36, 41 and 48, which were incorrectly given as

The ability to non-invasively monitor in-vivo the human muscle and adipose tissue is of great practical use and hence of growing interest in the fields of clinical diagnostics and preventive medicine. Optical methods, such as diffuse optical spectroscopy (DOS) applied in the near-infrared spectral region could be of great interest in clinical scenario. In this work, we present a pilot study based on multi-distance broadband time-domain diffuse optical spectroscopy (TD DOS) to characterize in vivo the subcutaneous adipose tissue (abdominal region) and the vastus lateralis muscle (thigh region). The study was performed using a fully automated portable TD DOS instrument on a set of 24 healthy adult volunteers. The optical properties of these two tissue types were obtained over the broad wavelength range of 600-1100 nm. The results suggest a clear influence of the stratified nature of the two regions considered, namely the abdomen and thigh, on the recovered optical properties. This work demonstrates how multi-distance broadband diffuse optical spectroscopy could be complimentary in fields like the non-invasive spectroscopy of adipose tissue and the standard DOS-based muscle oximetry.

The use of technologies still under development (Silicon PhotoMultipliers and Time-to-Digital Converter) for the upgrade of our time-resolved optical mammograph highlighted the crucial need for a thorough and progressive instrument characterization (from extensive laboratory tests on phantoms to in vivo measurements), potentially of general interest. Despite satisfying results on phantoms, in vivo tests urged an instrumental change, with the adoption of a just released high-throughput TDC to obtain high-quality breast scans (much wider scan area, better day-by-day reproducibility, improved signal quality, simpler set-up). A clinical study on monitoring of neoadjuvant chemotherapy is now ongoing at the San Raffaele Hospital, Milan.

Accurate monitoring of treatment is crucial in minimally-invasive radiofrequency ablation in oncology and cardiovascular disease. We investigated alterations in optical properties of ex-vivo bovine tissues of the liver, heart, muscle, and brain, undergoing the treatment. Time-domain diffuse optical spectroscopy was used, which enabled us to disentangle and quantify absorption and reduced scattering spectra. In addition to the well-known global (1) decrease in absorption, and (2) increase in reduced scattering, we uncovered new features based on sensitive detection of spectral changes. These absorption spectrum features are: (3) emergence of a peak around 840 nm, (4) redshift of the 760 nm deoxyhemoglobin peak, and (5) blueshift of the 970 nm water peak. Treatment temperatures above 100 °C led to (6) increased absorption at shorter wavelengths, and (7) further decrease in reduced scattering. This optical behavior provides new insights into tissue response to thermal treatment and sets the stage for optical monitoring of radiofrequency ablation.

A study on 118 subjects, performed with TD-fNIRS, demonstrated that the glaucoma has a cerebral component. The fNIRS parameters that best represent this finding are the OHB and HHB amplitudes, as revealed by PCA.

TD-NIRS allows the monitoring of tissue hemodynamics enhancing the contribution from the late (deeper) photons. After a brief review of its peculiarities, examples of its employment in clinics, on brain and muscles, will be presented

3D filament printers are nowadays used in diffuse optics for custom probes or phantoms boxes fabrication. We observed that not all the PLA filaments are suitable for NIRS and DCS applications.

The human abdominal region is very heterogeneous and stratified with subcutaneous adipose tissue (SAT) being one of the primary layers. Monitoring this tissue is crucial for diagnostic purposes and to estimate the effects of interventions like caloric restriction or bariatric surgery. However, the layered nature of the abdomen poses a major problem in monitoring the SAT in a non-invasive way by diffuse optics. In this work, we examine the possibility of using multi-distance broadband time domain diffuse optical spectroscopy to assess the human abdomen non-invasively. Broadband absorption and reduced scattering spectra from 600 to 1100 nm were acquired at 1, 2 and 3 cm source-detector distances on ten healthy adult male volunteers, and then analyzed using a homogeneous model as an initial step to understand the origin of the detected signal and how tissue should be modeled to derive quantitative information. The results exhibit a clear influence of the layered nature on the estimated optical properties. Clearly, the underlying muscle makes a relevant contribution in the spectra measured at the largest source-detector distance for thinner subjects related to blood and water absorption. More unexpectedly, also the thin superficial skin layer yields a direct contamination, leading to higher water content and steeper reduced scattering spectra at the shortest distance, as confirmed also by simulations. In conclusion, provided that data analysis properly accounts for the complex tissue structure, diffuse optics may offer great potential for the continuous non-invasive monitoring of abdominal fat.

We investigate the use of broadband time-domain diffuse optical spectroscopy (TD-DOS) to track in real time the changes in the optical properties of biological tissue undergoing radio frequency (RF) based thermal treatment.

A multivariate method integrating time-domain and space-domain techniques of near-infrared spectroscopy is proposed for simultaneously retrieving the absolute quantities of optical scattering and absorption properties in tissues. The concept is theoretically demonstrated by Monte-Carlo simulations in the homogenous case, and then applied on two-layer liquid phantoms. The deviations from nominal values are typically less than 6% for absorption coefficients in both layers

Glaucoma is a multifactorial optic neuropathy characterized by progressive loss of retinal ganglion cells, changes in optic disk morphology and visual field defects; its pathophysiology is still unclear. Recently it was demonstrated that glaucoma can be associated with a degenerative effect at the level of the optic nerve and the primary visual cortex. Functional near infrared spectroscopy (fNIRS) is a non-invasive optical technique, which allows the brain hemodynamic monitoring. In particular, the Time Domain fNIRS (TD-fNIRS) allows to remove from the detected signal the contribution coming from the surface (scalp, skull and cerebral fluid) in order to obtain the brain hemodynamic activation. The aim of this preliminary study is to understand if in the glaucomatous patients, the visual cortex activation during a visual stimulus is different from the one of a control group. A total of 20 subjects took part to the study. We divided them into three groups: 7 controls, 5 ocular hypertension (HYPER), and 8 glaucoma. The hemodynamic time courses of oxy- (OHB) and deoxy- (HHB) hemoglobin were compared with a hemodynamic response function (HRF) with the adaptive HRF approach. Finally, an inference test was applied (t-student) to statistically determine the visual cortex activation (simultaneous increase in OHB and decrease in HHB). The p-value threshold was set at 0.05. The 86% of the controls and the 80% of the HYPER combinations are activated; while the 81% of the glaucoma ones are not, outlining a well-defined trend. Also the OHB and HHB show drastic differences between controls and patients.

A recent upgrade of the time domain multi-wavelength optical mammograph developed by Politecnico di Milano achieved good performance in laboratory tests [Biomed. Opt. Express 9, 755 (2018).10.1364/BOE.9.000755]. However, it proved unsatisfactory when in vivo measurements were finally performed. That led to a further upgrade, including the replacement of the time-to-digital converter with a new model, and the related set-up changes. The new instrument version offers improved laboratory performance (as assessed through established protocols: BIP and MEDPHOT) and good in vivo performance (extension of the scanned breast area, repeatability, consistency of estimated tissue composition with physiology). Besides introducing the new set-up and detailing its laboratory and in vivo performance, we highlight the importance of systematic in vivo testing before entering clinical trials.

A periodic monitoring of the adipose tissue functions due to interventions, such as calorie restriction and bariatric surgery, or pathophysiological processes, has an increasing relevance in clinical diagnostics. Diffuse Optical Spectroscopy (DOS) is a valuable non-invasive tool that can be used in that direction. In this work, we present a pilot study based on Time Domain Broadband Diffuse Optical Spectroscopy (TD DOS) to characterize in vivo the subcutaneous fat tissue in the abdominal region. A first of its kind, portable TD DOS instrumentation, already enrolled in clinical studies, was used. Three healthy male volunteers were considered. Three source-detector separation distances (1, 2, and 3 cm) were used over the broad wavelength range of 600-1100 nm. The analysis was performed using a method based on a heterogeneous model to account for the multi-layered nature of the subcutaneous adipose tissue, and to obtain the optical properties specific to this fat localization. Inter-subject variation of tissue composition data was observed.

A novel detection chain, based on 8 Silicon Photomultipliers (forming a wide-area custom-made detection probe) and on a time-to-digital converter, was developed to improve the signal level in multi-wavelength (635-1060 nm) time domain optical mammography. The performances of individual components and of the overall chain were assessed using established protocols (BIP and MEDPHOT). The photon detection efficiency was improved by up to 3 orders of magnitude, and the maximum count rate level was increased by a factor of 10 when compared to the previous system, based on photomultiplier tubes and conventional time-correlated single-photon counting boards. In the estimate of optical parameters, the novel detection chain provides performances comparable to the previous system, widely validated in clinics, but with higher signal level, higher robustness, and at a lower price per channel, thus targeting important requirements for clinical applications. (C) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

We investigate the effect of depth heterogeneity in the abdomen by multidistance time-domain diffuse optical spectroscopy on 4 volunteers finding a higher water content in shallower regions, possibly due to fat heterogeneity and/or dermis contributions.

To enhance photon harvesting and improve data quality, an 8-channel compact SiPM probe and TDC acquisition replace PMTs and TCSPC boards in a time-resolved optical mammograph still providing similar performances for optical properties estimation.

Collagen content quantified through 7-wavelength (635-1060 nm) time domain diffuse optical mammography in 200 women proved key to discriminate malignant from benign breast lesions, to measure breast density, and to estimate breast cancer risk.

We present a new technique, Frequency Offset Raman Spectroscopy (FORS), for probing deep layer Raman spectra of diffusive media. It was demonstrated on a tissue mimicking phantom, and shows potential for in vivo applications.

An 8-channel Silicon PhotoMultiplier (SiPM) probe and Time-to-Digital-Converter (TDC) realize a higher-throughput, cheaper and compact detection chain for time-resolved optical mammography than photomultiplier tubes (PMTs) and Time Correlated Single Photon Counting (TCSPC) boards, providing comparable estimate of optical properties with increased optical responsivity.

We present a new technique, frequency offset Raman spectroscopy (FORS), to probe Raman spectra of diffusive media in depth. The proposed methodology obtains depth sensitivity exploiting changes in optical properties (absorption and scattering) with excitation wavelengths. The approach was demonstrated experimentally on a two-layer tissue phantom and compared with the already consolidated spatially offset Raman spectroscopy (SORS) technique. FORS attains a similar enhancement of signal from deep layers as SORS, namely 2.81 against 2.62, while the combined hybrid FORS-SORS approach leads to a markedly higher 6.0 enhancement. Differences and analogies between FORS and SORS are discussed, suggesting FORS as an additional or complementary approach for probing heterogeneous media such as biological tissues in depth.

Several techniques are being investigated as a complement to screening mammography, to reduce its false-positive rate, but results are still insufficient to draw conclusions. This initial study explores time domain diffuse optical imaging as an adjunct method to classify non-invasively malignant vs benign breast lesions. We estimated differences in tissue composition (oxy- and deoxyhemoglobin, lipid, water, collagen) and absorption properties between lesion and average healthy tissue in the same breast applying a perturbative approach to optical images collected at 7 red-near infrared wavelengths (635–1060 nm) from subjects bearing breast lesions. The Discrete AdaBoost procedure, a machine-learning algorithm, was then exploited to classify lesions based on optically derived information (either tissue composition or absorption) and risk factors obtained from patient’s anamnesis (age, body mass index, familiarity, parity, use of oral contraceptives, and use of Tamoxifen). Collagen content, in particular, turned out to be the most important parameter for discrimination. Based on the initial results of this study the proposed method deserves further investigation.

An 8-channel Silicon Photomultiplier probe and a Time-toDigital Converter are used to build a higher-throughput, cheaper and compact detection chain for time-resolved optical mammography as compared with conventional PhotoMultiplier Tubes and Time-Correlated Single-Photon Counting boards, still providing comparable performance in the estimation of optical properties, but with higher optical responsivity.

Diffuse optical imaging and spectroscopy of the female breast is an area of active research. We review the present status of this field and discuss the broad range of methodologies and applications. Starting with a brief overview on breast physiology, the remodeling of vasculature and extracellular matrix caused by solid tumors is highlighted that is relevant for contrast in optical imaging. Then, the various instrumental techniques and the related methods of data analysis and image generation are described and compared including multimodality instrumentation, fluorescence mammography, broadband spectroscopy, and diffuse correlation spectroscopy. We review the clinical results on functional properties of malignant and benign breast lesions compared to host tissue and discuss the various methods to improve contrast between healthy and diseased tissue, such as enhanced spectroscopic information, dynamic variations of functional properties, pharmacokinetics of extrinsic contrast agents, including the enhanced permeability and retention effect. We discuss research on monitoring neoadjuvant chemotherapy and on breast cancer risk assessment as potential clinical applications of optical breast imaging and spectroscopy. Moreover, we consider new experimental approaches, such as photoacoustic imaging and long-wavelength tissue spectroscopy.

Top 15% age-matched collagen content (estimated on 109 subjects by optical mammography) and high mammographic density identify different subgroups of high cancer occurrence, suggesting collagen is an independent breast cancer risk factor.

We present a new compact system for time-domain diffuse optical spectroscopy of highly scattering media operating in the wavelength range from 1100 nm to 1700 nm. So far, this technique has been exploited mostly up to 1100 nm: we extended the spectral range by means of a pulsed supercontinuum light source at a high repetition rate, a prism to spectrally disperse the radiation, and a time-gated InGaAs/InP single-photon avalanche diode working up to 1700 nm. A time-correlated single-photon counting board was used as processing electronics. The system is characterized by linear behavior up to absorption values of about 3.4 cm−1 where the relative error is 17%. A first measurement performed on lipids is presented: the absorption spectrum shows three major peaks at 1200 nm, 1400 nm, and 1700 nm.

The potential disturbance in the prefrontal cortex hemodynamic signal measured by functional near infrared spectroscopy (NIRS), due to forehead skin flowmotion, detected by laser Doppler flowmetry, was investigated by a standard protocol of hemodynamic challenge by Valsalva maneuver, aimed at assessing and disentangling local regulatory responses in skin vasomotion and in cerebral perfusion in presence of a strong systemic drive, and to quantify the common information in the two signals. The deep cortical NIRS signal did not appear to be affected by surface vasomotor activity, and autoregulation dynamics were dominant with respect to autonomic control of circulation. Highlights? Functional near infrared spectroscopy (fNIRS) prefrontal cortex measurements. ? Laser Doppler flowmetry (LDF) measurements of right and left temple vasomotions. ? Dynamic responses of prefrontal cortex autoregulation and skin vasomotion to a Valsalva maneuver. ? Cerebral and skin autoregulation were uncorrelated under the systemic stimulus due to Valsalva.

A review of near infrared (NIR) spectroscopy of the female breast performed using time domain broadband systems is presented, summarising the key studies performed at Politecnico di Milano. The time domain approach, based on pulsed tunable lasers and single-photon detection, makes it possible to uncouple absorption from scattering contributions and to derive tissue optical properties in vivo non-invasively. The basic tissue absorbers in the 600–1100 nm range are discussed, together with the interpretation of the scattering spectra. Inter- and intra-subject variations in breast optical properties are addressed based on in vivo measurements on different women and on the same subject as a function of the menstrual cycle phase and of the measurement geometry. Results demonstrate that a specific breast type can be identified for each woman, ultimately related to the water, lipid and collagen content and to the scattering properties. As an example of the application of spectroscopy-derived information, we discuss the non-invasive optical detection of breast density as an important risk factor for breast cancer, envisaging an attractive contribution of NIR spectroscopy to the fight against breast cancer on both a medical diagnostics and research level.

Investigations of wall paintings by Masolino da Panicale in the Baptistery of Castiglione Olona were conducted using a multi-analytical approach, based on in situ fluorescence imaging, multispectral reflectance imaging and non-destructive analysis of a historical cross-section. Fluorescence imaging of wall paintings, mainly focused on the discrimination and identification of organic compounds, has been conducted with a novel approach, which incorporates the use of spectrally-resolved and lifetime-resolved imaging devices, applied together for the first time for the analysis of paintings. Analysis of the UV-induced emissions from the surface of the paintings allowed the documentation of the selective use of a carmine-based red lake, identified using micro-Raman spectroscopy and Scanning Electron Microscopy. Visible reflectance measurements highlighted the distribution and use of different inorganic pigments. Finally, the in situ study, with the support of early 20th century photographs, provided additional information on Masolino's style and revealed details and decorative elements of the painting, which are indiscernible under standard illumination. (C) 2010 Elsevier Masson SAS. All rights reserved.

We present a novel technique for wide dynamic range optical investigations. It is based on a fast-gated silicon single-photon avalanche diode (SPAD) in time-correlated single-photon counting (TCSPC) setup. The SPAD is gated-on and off in 500 ps so as to detect photons only within a given time interval. This technique is particularly useful in applications where a large amount of unnecessary photons precede or follow the optical signal to be detected, such as in time-resolved near infrared (NIR) spectroscopy, optical mammography, and optical molecular imaging. In particular, in time-resolved reflectance spectroscopy, it is desirable to minimize the source-detector separation to improve system performance. This leads to the saturation of the detection electronics because of the huge amount of “early” photons back scattered by superficial layers. Our setup is able to reject these photons and detect only “late” photons from the sample, thus allowing an increase in the dynamic range and the injected power. We acquired diffusive curves of two phantoms with 95 ps time resolution and 107 dynamic range with a measurement time three orders of magnitude shorter than what is currently possible with a standard TCPSC setup.

The non-destructive determination of layer structures in works of art remains a significant challenge. Non-linear microscopy and confocal Raman microscopy (CRM) were employed for characterisation of varnish-media layers in model samples, providing important information regarding the thickness of materials and the identification of different media in depth. Commonly found triterpenoid varnishes mastic and dammar were applied over a single layer of films of linseed oil. Non-linear microscopy of samples was carried out using a 1028-nm femtosecond laser source; both third-harmonic generation signals (THG) and three-photon fluorescence signals (3PEF) of samples were collected in an effort to measure the thickness of mono- and bi-layers; in parallel scans of larger areas were undertaken to assess heterogeneities in samples with spatial resolution of ∼2 μm. Complementary spectroscopic information from CRM collected with both a 514.5-nm argon-ion and a 785-nm diode lasers coupled with a 100X objective and a motorised stage was carried out. Comparison of C–H stretching regions of Raman spectra allowed the differentiation between different molecular materials and the fingerprint region was employed for the depth profiling of the samples.

Purpose: Sustained attention is one of the most important cognitive abilities for the management of everyday life, but it is often studied only at the behavioral level, while functional correlates are scarcely investigated. In this article, the authors address the topic of characterizing the dynamics of cerebral metabolism in the prefrontal cortex during a task of prolonged attention. Method: By means of multichannel time-resolved functional near-infrared spectroscopy and generalized linear model based data processing, the authors measured the hemodynamic response of the prefrontal cortex from 19 healthy subjects to a shortened version of a sustained attention task (Conners’ Continuous Performance Test), lasting for 10 min . Results: The task elicited significant brain activation, which did not remain constant for the entire task, but showed a drop not correlated with performance decay 4 min after the beginning of the task. Furthermore, oxygenated hemoglobin showed an increasing trend also during the first phase of the recovery, just after the end of the task. Conclusion: The results indicate a nontrivial dynamics of neural activation, habituation processes, and hemodynamic/metabolic coupling. These results encourage further studies about continuous stimulation of cognitive functions on both healthy and pathological subjects.

The assessment of the influence of natural and artificial ageing on the spectrofluorescence of triterpenoid varnishes dammar and mastic is the focus of this work. Both Fourier transform infrared (FTIR) microscopy using attenuated total reflectance and Raman spectroscopy have been employed for complementary molecular analysis of samples. Synchronous fluorescence spectroscopy, excitation emission spectroscopy, and statistical analysis of data have been used to monitor changes in the optical properties of varnish samples. Assessment of naturally and artificially aged samples using excitation emission spectroscopy suggests that extensive exposure to visible light does not lead to easily appreciable differences in the fluorescence of mastic and dammar; cluster analysis has been used to assess changes, which occur with artificial ageing under visible light, indicating that differences in the fluorescence spectra of aged triterpenoids may be insufficient for their discrimination. The results highlight significant differences between the initial fluorescence of films of dammar and mastic and the fluorescence, which develops with ageing and oxidation, and specific markers, which change with ageing in FTIR and Raman spectra, have been identified.

Recent interest in the fluorescence of binding media and varnishes (proteins, oils, and resins) commonly used in paintings is based on the potential for discriminating these organic materials. A useful way of studying the presence of the broad-band fluorescence emissions found in these complex organic materials is fluorescence excitation emission spectroscopy. However, due to the presence of Raman and Rayleigh scattering which may necessitate correction or preprocessing for statistical analysis and visualization, an alternative approach has been adopted for the analysis of different samples of artist materials based on total synchronous fluorescence spectroscopy. Films of selected drying oils, glue, egg, and casein and the resins mastic, dammar, copal, and shellac were analyzed using total synchronous fluorescence spectroscopy, and an interpretation of the differences between spectra is given. A data reduction method based on the transformation of fluorescence contours extracted from total synchronous fluorescence from Cartesian to polar coordinates is presented and is followed by the comparison of data using multivariate analysis and hierarchical cluster analysis. Results suggest that the new method can be used to classify samples on the basis of their fluorescence spectra, clearly differentiating oils, resins, and protein-based media into groups.

This paper discusses the spectral distortions occurring when time-resolved spectroscopy of diffusive media is performed illuminating with a wide bandpass. It is shown that the spectral region within the bandpass that exhibits the lowest absorption will dominate the resulting time-resolved curve, leading to significant underestimations of absorption as well as distortions in the spectral shape (including shifts in peak positions). Due to the nonlinear behavior of absorption, this effect becomes even more pronounced when including longer and longer photon path lengths. First, a theoretical treatment of the problem is given, and then the distortion is described by time-resolved reflectance simulations and experimental measurements of lipid and water samples. A spectrally constrained data analysis is proposed that takes into account the spectrum of the light injected into the sample, used to overcome the distortion and improve the accuracy of the estimation of chromophore concentrations from absorption spectra. Measurements on a lipid sample show a reduction of the error from 30% to 6%.

We compared the effectiveness of three optical techniques based on fluorescence imaging and spectroscopy with indocyanine green (ICG) contrast agent to evaluate in vivo the disruption of the active vasculature induced by a vascular targeting agent. The blood perfusion of the MDA-MB-435 tumor model transplanted in nude mice was estimated from the signal of the contrast agent measured immediately after its systemic injection in mice. Optical measurements were performed using a fluorescence imaging setup and a fiber-based time correlated single photon counting (TCSPC) apparatus. This latter apparatus was used to measure the tumor fluorescence in transmittance geometry and the change in the basal optical absorption induced by the contrast agent, thus providing an alternative estimation of the blood content in the tumor. Mice were divided into four groups. Three groups were treated with different doses of the vascular disrupting agent ZD6126, the fourth group (control group) received the drug vehicle only. Optical measurements were carried out 3 h after pharmacologic treatment. After 24 h, mice were killed, tumors were excised and the extent of necrosis was evaluated with standard histologic analysis. On fluorescence imaging ICG emission from tumors of mice treated with ZD6126 significantly was lower compared with the emission from control mice. The histologic sections also showed a significantly higher amount of necrosis in tumors of treated mice. Both these findings, which correlate with each other, indicate an effective vascular shutdown induced by the drug. However, ICG fluorescence measured with the TCSPC apparatus in transmittance geometry and the estimate of the change in optical absorption did not allow a statistically significant differentiation between treated and control groups.

The maturity at harvest of nectarines can be assessed with the novel technique of time-resolved reflectance spectroscopy (TRS) measuring the light absorption at 670 nm in the fruit flesh. A kinetic model was developed that links this absorption coefficient (mu(a)), expressed as the biological shift factor, to firmness decrease during ripening. The model thus includes the variations in maturity at harvest of the individual fruit. In non-linear regression analyses of data from four different seasons, the explained part ranged from 81 to 92% for cv 'Spring Bright'. The kinetic parameters values obtained were highly similar in different seasons. The results suggest that in nectarines the degreening of fruit flesh, expressed as TRS absorption at 670 run, is synchronised with the softening. The distribution of mu(a) was skewed, but that of the biological shift factor, derived from mu(a), was normal. By measuring the colour of fruit flesh with the non-destructive and very rapid TRS technique, and applying the model parameters, individual fruit can be graded at harvest into classes of usability, selecting fruit with different ripening stages for different market segments and predicting their softening time, thereby guaranteeing sufficient firmness to transport the fruit and sufficient ripening potential to reach good eating quality upon arrival in the receiving regions or countries. Consumers therefore will be more satisfied, encouraging them to repeated purchase. Retailers and wholesalers will be more satisfied since fruit unfit for sale not longer needs to be transported. (c) 2007 Elsevier B.V. All rights reserved.