Novel approaches to photon detection and timing for 7-wavelength time domain optical mammography

An 8-channel Silicon Photomultiplier probe and a Time-to-Digital 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

Multi Simulation Platform for Time Domain Diffuse Optical Tomography: An Application to a Compact Hand-Held Reflectance Probe

Time Domain Diffuse Optical Tomography (TD-DOT) enables a full 3D reconstruction of the optical properties of tissue, and could be used for non-invasive and cost-effective in-depth body exploration (e.g., thyroid and breast imaging). Performance quantification is crucial for comparing results coming from different implementations of this technique. A general-purpose simulation platform for TD-DOT clinical systems was developed with a focus on performance assessment through meaningful figures of merit. The platform was employed for assessing the feasibility and characterizing a compact hand-held probe for breast imaging and characterization in reflectance geometry. Important parameters such as hardware gating of the detector, photon count rate and inclusion position were investigated. Results indicate a reduced error (<10%) on the absorption coefficient quantification of a simulated inclusion up to 2-cm depth if a photon count rate ≥ 10^{6} ounts per second is used along with a good localization (error < 1 mm down to 25 mm-depth)

SOLUS: An innovative multimodal imaging system to improve breast cancer diagnosis through diffuse optics and ultrasounds

To improve non-invasively the specificity in the diagnosis of breast cancer after a positive screening mammography or doubt/suspicious ultrasound examination, the SOLUS project developed a multimodal imaging system that combines: B-mode ultrasound (US) scans (to assess morphology), Color Doppler (to visualize vascularization), shear-wave elastography (to measure stiffness), and time domain multi-wavelength diffuse optical tomography (to estimate tissue composition in terms of oxy- and deoxy-hemoglobin, lipid, water, and collagen concentrations). The multimodal probe arranges 8 innovative photonic modules (optodes) around the US transducer, providing capability for optical tomographic reconstruction. For more accurate estimate of lesion composition, US-assessed morphological priors can be used to guide the optical reconstructions. Each optode comprises: i) 8 picosecond pulsed laser diodes with different wavelengths, covering a wide spectral range (635-1064 nm) for good probing of the different tissue constituents; ii) a large-area (variable, up to 8.6 mm2) fast-gated digital Silicon Photomultiplier; iii) the acquisition electronics to record the distribution of time-of-flight of the re-emitted photons. The optode is the basic element of the optical part of the system, but is also a stand-alone, ultra-compact (about 4 cm3) device for time domain multi-wavelength diffuse optics, with potential application in various fields

Multi-laboratory efforts for the standardization of performance assessment of diffuse optics instruments - The BitMap Exercise

A multi-laboratory exercise, involving 29 diffuse optical instruments, aimed at performance assessment of diffuse optics instruments on standardized protocols is presented. The overarching methodology and future actions will also be discussed

A multi-laboratory comparison of photon migration instruments and their performances – the BitMap Exercise

Performance assessment and standardization are indispensable for instruments of clinical relevance in general and clinical instrumentation based on photon migration/diffuse optics in particular. In this direction, a multi-laboratory exercise was initiated with the aim of assessing and comparing their performances. 29 diffuse optical instruments belonging to 11 partner institutions of a European level Marie Curie Consortium BitMap1 were considered for this exercise. The enrolled instruments covered different approaches (continuous wave, CW; frequency domain, FD; time domain, TD and spatial frequency domain imaging, SFDI) and applications (e.g. mammography, oximetry, functional imaging, tissue spectroscopy). 10 different tests from 3 well-accepted protocols, namely, the MEDPHOT2, the BIP3, and the nEUROPt4 protocols were chosen for the exercise and the necessary phantoms kits were circulated across labs and institutions enrolled in the study. A brief outline of the methodology of the exercise is presented here. Mainly, the design of some of the synthetic descriptors, (single numeric values used to summarize the result of a test and facilitate comparison between instruments) for some of the tests will be discussed.. Future actions of the exercise aim at deploying these measurements onto an open data repository and investigating common analysis tools for the whole dataset

In vivo test-driven upgrade of a time domain multi-wavelength optical mammograph

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).]. 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

Optical mammography in the time domain up to 1060 nm: From tests on healthy women to initial data for monitoring neoadjuvant chemotherapy

We present in vivo tests on healthy women through our optical mammograph in preparation for a clinical validation on neoadjuvant chemotherapy monitoring, and we report preliminary data on the first patient enrolled in the study

In vivo validation of time domain optical mammograph with high-sensitivity detection chain

Optical mammography is an application of diffuse optics that combines the advantages of cost-effectiveness, non-invasiveness, no significant dependence on breast density and capability to derive information about breast composition. Literature reports promising preliminary results when employed for breast cancer risk assessment, lesion characterisation, therapy monitoring and prediction of therapy outcome. In view of a clinical trial on the monitoring of neoadjuvant chemotherapy, we upgraded our time domain multi-wavelength optical mammograph exploiting new technology based on silicon photomultipliers and high throughput time-to-digital conversion. The setup is presented, together with the validation of its performances via laboratory and in vivo tests

A Tool for quantitative and systematic simulation of diffuse optical tomography with a limited number of fixed sources and detectors

Quantitative Time-Domain Diffuse Optical Tomography simulations are systematically performed through a developed tool. Reflectance geometry and fixed sources and detectors provide 4 mm localization error and 80% accuracy on reconstructed absorption in depth (2 cm)

In vivo validation of time domain optical mammograph with high-sensitivity detection chain

Optical mammography is an application of diffuse optics that combines the advantages of cost-effectiveness, non-invasiveness, no significant dependence on breast density and capability to derive information about breast composition. Literature reports promising preliminary results when employed for breast cancer risk assessment, lesion characterisation, therapy monitoring and prediction of therapy outcome. In view of a clinical trial on the monitoring of neoadjuvant chemotherapy, we upgraded our time domain multi-wavelength optical mammograph exploiting new technology based on silicon photomultipliers and high throughput time-to-digital conversion. The setup is presented, together with the validation of its performances via laboratory and in vivo test