With the development of optical coherence tomography, the application optical coherence elastography (OCE) has gained more and more attention in biomechanics for its unique features including micron-scale resolution, real-time processing, and non-invasive imaging. In this review, one group of OCE techniques, namely dynamic OCE, are introduced and discussed including external dynamic OCE mapping and imaging of ex vivo breast tumor, external dynamic OCE measurement of in vivo human skin, and internal dynamic OCE including acoustomotive OCE and magnetomotive OCE. These techniques overcame some of the major drawbacks of traditional static OCE, and broadened the OCE application fields. Driven by scientific needs to engineer new quantitative methods that utilize the high micron-scale resolution achievable with optics, results of biomechanical properties were obtained from biological tissues. The results suggest potential diagnostic and therapeutic clinical applications. Results from these studies also help our understanding of the relationship between biomechanical variations and functional tissue changes in biological systems.

The source of energy for life is the tissue mitochondria and they demand a complex chain of biochemicals to ensure proper physiological function. Classically, the blood levels, and not the tissue levels of these metabolites, are determined by expensive and time-consuming biochemical analyses. Since the tissue mitochondria are the consumers of the substrates of glycolysis and of fatty acid metabolism, their redox state is a unique accessible monitor of tissue metabolism and its blockade due to toxins.

The photoacoustic effect was employed to generate short-duration quasi-unipolar acoustic pressure pulses in both planar and spherically focused geometries. In the focal region, the temporal profile of a pressure pulse can be approximated by the first derivative of the temporal profile near the front transducer surface, with a time-averaged value equal to zero. This approximation agreed with experimental results acquired from photoacoustic transducers with both rigid and free boundaries. For a free boundary, the acoustic pressure in the focal region is equal to the sum of a positive pressure that follows the spatial profile of the optical energy deposition in the medium and a negative pressure that follows the temporal profile of the laser pulse.

Measurement of both oxygen saturation and blood flow in the retinal vessels has proved to give important information about the eye health and the onset of eye pathologies such as diabetic retinopathy. In this study, we present the implementation, on a commercially available fundus camera, of a retinal imager and a retina blood flow velocimeter. The retinal imager uses division of aperture to acquire nine wavelength-dependent sub-images of the retina. Careful consideration is taken to improve image transfer by measuring the optical properties of the fundus camera and modeling the optical train in Zemax. This part of the setup is calibrated with optical phantoms of known optical properties that are also used to build a lookup table (LUT) linking phantom optical properties to measured reflectance. The retina blood flow velocimeter relies on tracking clusters of erythrocytes and uses a fast acquisition camera attached to a zoom lens, with a green illumination LED-engine. Calibration is provided using a calibrated quartz capillary tube and human blood at a known flow rate. Optical properties of liquid phantoms are retrieved from measured reflectance using the LUT, and blood flow measurements in the retina are presented.

We have examined ten human subjects with a previously developed instrument for near-infrared diffuse spectral imaging of the female breast. The instrument is based on a tandem, planar scan of two collinear optical fibers (one for illumination and one for collection) to image a gently compressed breast in a transmission geometry. The optical data collection features a spatial sampling of 25 points/cm2 over the whole breast, and a spectral sampling of 2 points/nm in the 650– 900nm wavelength range. Of the ten human subjects examined, eight are healthy subjects and two are cancer patients with unilateral invasive ductal carcinoma and ductal carcinoma in situ, respectively. For each subject, we generate second-derivative images that identify a network of highly absorbing structures in the breast that we assign to blood vessels. A previously developed paired-wavelength spectral method assigns oxygenation values to the absorbing structures displayed in the second-derivative images. The resulting oxygenation images feature average values over the whole breast that are significantly lower in cancerous breasts (69±14%, n = 2) than in healthy breasts (85±7%, n = 18) (p < 0.01). Furthermore, in the two patients with breast cancer, the average oxygenation values in the cancerous regions are also significantly lower than in the remainder of the breast (invasive ductal carcinoma: 49±11% vs 61±16%, p < 0.01; ductal carcinoma in situ: 58±8% vs 77±11%, p < 0.001).

Metastasis to distant sites is a severe treatment challenge and a major cause of death for breast cancer patients. Laser immunotherapy (LIT) is a novel technique, combining a selective photothermal therapy with local application of glycated chitosan, a potent immunoadjuvant. The pre-clinical studies of LIT have shown its unique characteristics in generating specific antitumor immunity. The clinical application of LIT in the treatment of melanoma patients has achieved preliminary success. Recently, LIT has been used to treat late-stage breast cancer patients. Here we report for the first time the clinical results of this combination therapy in breast cancer patients. The LIT treatment procedures are presented and the medical history of two stage IV breast cancer patients is reviewed. Most of the breast cancer lesions and the metastasis of lung and brain disappeared after repeated treatments of LIT. One patient achieved complete 279 J. Innov response; the other achieved partial response at the time of this report. Although there is still a long way for LIT to become a standard modality for breast cancer treatment, the results of this study indicated its promising future.

Since numerous characteristic absorption lines caused by molecular vibration exist in the midinfrared (MIR) wavelength region, selective excitation or selective dissociation of molecules is possible by tuning the laser wavelength to the characteristic absorption lines of target molecules. By applying this feature to the medical fields, less-invasive treatment and non-destructive diagnosis with absorption spectroscopy are possible using tunable MIR lasers. A high-energy nanosecond pulsed MIR tunable laser was obtained with difference-frequency generation (DFG) between a Nd:YAG and a tunable Cr:forsterite lasers. The MIR-DFG laser was tunable in a wavelength range of 5.5–10μm and generated laser pulses with energy of up to 1.4mJ, a pulse width of 5 ns, and a pulse repetition rate of 10 Hz. Selective removal of atherosclerotic lesion was successfully demonstrated with the MIR-DFG laser tuned at a wavelength of 5.75 μm, which corresponds to the characteristic absorption of the ester bond in cholesterol esters in the atherosclerotic lesions. We have developed a non-destructive diagnostic probe with an attenuated total reflection (ATR) prism and two hollow optical fibers. An absorption spectrum of cholesterol was measured with the ATR probe by scanning the wavelength of the MIR-DFG laser, and the spectrum was in good agreement with that measured with a commercial Fourier transform infrared spectrometer.

It is well acknowledged that the equation of radiative transfer (ERT) provides an accurate prediction of light propagation in biological tissues, while the diffusion approximation (DA) is of limited accuracy for the transport regime. However, ERT-based reconstruction codes require much longer computation times as compared to DA-based reconstruction codes. We introduce here a computationally efficient algorithm, called a diffusion–transport hybrid solver, that makes use of the DA- or low-order ERT-based inverse solution as an initial guess for the full ERT-based reconstruction solution. To evaluate the performance of this hybrid method, we present extensive studies involving numerical tissue phantoms and experimental data. As a result, we show that the hybrid method reduces the reconstruction time by a factor of up to 23, depending on the physical character of the problem.

Diabetic neuropathy (DN) is, at least in part, associated with the functional attenuation of vasa nervorum, the microvascular structure of peripheral nerves. Microvascular imaging options for vasa nervorum still remain limited. In this work, optical microangiography (OMAG), a volumetric, label-free imaging technique, is utilized for characterizing, with high resolution, blood perfusion of peripheral nerve in diabetic mice. We demonstrate that OMAG is able to visualize the structure of microvasculature and to quantify the changes of dynamic blood flow and vessel diameters during administration of vessel stimulant in both diabetic and normal mice. The results indicate the potential of OMAG to assess the blood supply of nerve involved in the pathology and treatment of DN.

In this paper, amino capped CdSe/ZnS quantum dots (QDs) were immobilized on the 11- mercaptoundecanoic acid (MUA) self-assembled Au surface (SAM/Au) by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Atomic force microscopy (AFM), fluorescence imaging and electrochemistry were employed to characterize the surface. The results showed that CdSe/ZnS QDs were immobilized on the surface of SAM/Au successfully. Based on this method, the fluorescence of the QDs on the SAM/Au was monitored on-line.

Steven L. Jacques received a B.S. degree in Biology from M.I.T., and an M.S. degree in Electrical Engineering and Computer Science as well as a Ph.D. degree in Biophysics and Medical Physics from the University of California, Berkeley (1984). For his doctoral research, he used dielectric microwave measurements to explore the in vivo distribution of water in the stratum corneum of human skin.