[show abstract][hide abstract] ABSTRACT: Near-infrared optical imaging targeting the intrinsic contrast of tissue hemoglobin has emerged as a promising approach for visualization of vascularity in cancer research. We evaluated the usefulness of diffuse optical spectroscopy using time-resolved spectroscopic (TRS) measurements for functional imaging of primary breast cancer.
Fifty-five consecutive TNM stageI/II patients with histologically proven invasive ductal carcinoma and operable breast tumors (<5 cm) who underwent TRS measurements were enrolled. Thirty (54.5%) patients underwent 18F-fluoro-deoxy-glucose (FDG) positron emission tomography with measurement of maximum tumor uptake. TRS was used to obtain oxyhemoglobin, deoxyhemoglobin, and total hemoglobin (tHb) levels from the lesions, surrounding normal tissue, and contralateral normal tissue. Lesions with tHb levels 20% higher than those present in normal tissue were defined as "hotspots," while others were considered "uniform." The findings in either tumor type were compared with clinicopathological factors.
"Hotspot" tumors were significantly larger (P = 0.002) and exhibited significantly more advanced TNM stage (P = 0.01), higher mitotic counts (P = 0.01) and higher levels of FDG uptake (P = 0.0004) compared with "uniform" tumors; however, other pathological variables were not significantly different between the two groups.
Optical imaging for determination of tHb levels allowed for measurement of tumor vascularity as a function of proliferation and glucose metabolism, which may be useful for prediction of patient prognosis and potential response to treatment.
BMC Cancer 10/2013; 13(1):514. · 3.33 Impact Factor
[show abstract][hide abstract] ABSTRACT: We examined the usefulness of near infrared time-resolved spectroscopy (TRS) for detection of vasospasm in subarachnoid hemorrhage (SAH). We investigated seven aneurysmal SAH patients with poor clinical conditions (WFNS grade V) who underwent endovascular coil embolization. Employing TRS, we measured the oxygen saturation (SO(2)) and baseline hemoglobin concentrations in the cortices. Measurements of TRS and transcranial Doppler sonography (TCD) were performed repeatedly for 14 days after SAH. In four of the seven patients, the SO(2) and hemoglobin concentrations measured in the brain tissue of the middle cerebral artery territory remained stable after SAH. However, in three patients, TRS revealed abrupt decreases in SO(2) and total hemoglobin between 5 and 9 days after SAH. Cerebral angiography performed on the same day revealed severe vasospasms in these patients. Although TCD detected the vasospasm in two of three cases, it failed to do so in one case. TRS could detect vasospasms after SAH by evaluating the cortical blood oxygenation.
Advances in experimental medicine and biology 01/2010; 662:505-11. · 1.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine the alterations in optical characteristics and cerebral blood oxygenation (CBO) in the frontal lobe during language tasks, we evaluated the changes in mean optical pathlength (MOP) and CBO induced by a verbal fluency task (VFT) in the right and left frontal lobes in normal adults (n = 9, mean age = 29.6 +/- 4.8 years). We employed a newly developed 8-channel time-resolved near-infrared spectroscopy (TRS) instrument. The results demonstrated differences in MOP in the fronto-temporal areas with subject and wavelength; however, there was no significant difference between the right and left sides (p > 0.05). Also, the VFT did not affect the MOP significantly as compared to that before the tasks (p > 0.05). In all of the recording regions, the VFT caused increases in concentration of oxyhemoglobin and total hemoglobin associated with a decrease in deoxyhemoglobin concentration, indicating that these cortical areas were activated by the VFT. However, the mean concentration changes of oxyhemoglobin and total hemoglobin on the left side were larger than those on the right side. In addition, functional MRI demonstrated that the inferior frontal gyrus on the left side was activated in the subjects who exhibited increases in oxyhemoglobin concentration in these areas. These results suggest that TRS may be useful to study language function and to assess hemispheric dominance for language.
Advances in experimental medicine and biology 01/2010; 662:213-8. · 1.83 Impact Factor
[show abstract][hide abstract] ABSTRACT: We developed a three-wavelength time-resolved spectroscopy (TRS) system, which allows quantitative measurement of hemodynamics within relatively large living tissue. We clinically evaluated this TRS system by monitoring cerebral circulation during cardiopulmonary bypass surgery. Oxyhemoglobin, deoxyhemoglobin, total hemoglobin and oxygen saturation (SO(2)) were determined by TRS on the left forehead attached with an optode spacing of 4 cm. We also simultaneously monitored jugular venous oxygen saturation (SjvO(2)) and arterial blood hematocrit (Hct) using conventional methods. The validity and usefulness of the TRS system were assessed by comparing parameters obtained with the TRS and conventional methods. Although the changes in SO(2) were lower than those in SjvO(2), SO(2) obtained by TRS paralleled the fluctuations in SjvO(2), and a good correlation between these values was observed. The only exceptions occurred during the perfusion period. Moreover, there was a good correlation between tHb and Hct values (r(2)=0.63). We concluded that time-resolved spectroscopy reflected the conditions of cerebral hemodynamics of patients during surgical operations.
Journal of Biomedical Optics 01/2007; 12(6):062112. · 2.88 Impact Factor
[show abstract][hide abstract] ABSTRACT: To determine the alterations in optical characteristics and cerebral blood oxygenation (CBO) during activation and deactivation, we evaluated the changes in mean optical pathlength (MOP) and CBO induced by a verbal fluency task (VFT) and driving simulation in the right and left prefrontal cortex (PFC), employing a newly developed time-resolved near infrared spectroscopy, which allows quantitative measurements of the evoked-CBO changes by determining the MOP with a sampling time of 1 s. The results demonstrated differences in MOP in the foreheads with the subjects and wavelength; however, there was no significant difference between the right and left foreheads (p > 0.05). Also, both the VFT and driving simulation task did not affect the MOP significantly as compared to that before the tasks (p > 0.05). In the bilateral PFCs, the VFT caused increases of oxyhemoglobin and total hemoglobin associated with a decrease of deoxyhemoglobin, while the driving simulation task caused decreases of oxyhemoglobin and total hemoglobin associated with an increase of deoxyhemoglobin; there were no significant differences in evoked-CBO changes between the right and left PFC. The present results will be useful for quantitative measurement of hemodynamic changes during activation and deactivation in the adults by near infrared spectroscopy.
Life Sciences 06/2006; 78(23):2734-41. · 2.56 Impact Factor
[show abstract][hide abstract] ABSTRACT: We compared pharmacologically-perturbed hemodynamic parameters (cerebral blood volume; CBV, and flow; CBF) by acetazolamide administration in six healthy human subjects studied with positron emission tomography (PET) and near-infrared (NIR) time-resolved spectroscopy (TRS) simultaneously to investigate whether NIR-TRS could measure in vivo hemodynamics in the brain tissue quantitatively. Simultaneously with the PET measurements, TRS measurements were performed at the forehead with four different optode spacing from 2 cm to 5 cm. Total hemoglobin and oxygen saturation (SO2) measured by TRS significantly increased after administration of acetazolamide at any optode spacing in all subjects. In PET study, CBV and CBF were estimated in the following three volumes of interest (VOIs) determined on magnetic resonance images, VOI1: scalp and skull, VOI2: gray matter region, VOI3: gray and white matter regions. Acetazolamide treatment elevated CBF and CBV significantly in VOI2 and VOI3 but VOI1. TRS-derived CBV was more strongly correlated with PET-derived counterpart in VOI2 and VOI3 when the optode spacing was above 4 cm, although optical signal from cerebral tissue could be caught with any optode spacing. As to increase of the CBV, 4 cm of optode spacing correlated best with VOI2. To support the result of TRS-PET experiment, we also estimated the contribution ratios of intracerebral tissue to observed absorption change based on diffusion theory. The contribution ratios at 4 cm were estimated as follows: 761 nm: 50%, 791 nm: 72%, 836 nm: 70%. These results demonstrated that NIR-TRS with 4 cm of optode spacing could measure cerebral hemodynamic responses optimally and quantitatively.
[show abstract][hide abstract] ABSTRACT: Our research goal is to develop diffuse optical tomography (DOT) capable of quantitative measurement. Information on optical pathlength is essential for reconstructing images with quantitative properties, and we have performed image reconstruction with a simulation model using a time-resolved photon path distribution (time-resolved PPD). The results showed that a DOT image reconstruction algorithm using this PPD is effective in quantifying the absorbers in a scattering medium such as human tissue. This algorithm uses a photon distribution independent of absorption by simply assuming that the measurement object is homogeneous, which means that PPD needs to be calculated only once. Our technique is therefore applicable to short-time imaging of measurement objects for which absorption changes flatness such as that in human tissue.
[show abstract][hide abstract] ABSTRACT: We report the successful application of reflectance diffuse optical tomography (DOT) using near-infrared light with the new reconstruction algorithm that we developed to the observation of regional hemodynamic changes in the brain under specific mental tasks. Our results reveal the heterogeneous distribution of oxyhemoglobin and deoxyhemoglobin in the brain, showing complementary images of oxyhemoglobin and deoxyhemoglobin changes in certain regions. We conclude that our reflectance DOT has practical potential for human brain mapping, as well as in the diagnostic imaging of brain diseases.
Japanese Journal of Applied Physics 01/2005; 44. · 1.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: A near infrared multi-channel time-resolved spectroscopy system has been developed. This system acquires the data with 0.2sec sampling time at 16 points, simultaneously. Absorption change can be determined within 3 % accuracy.
[show abstract][hide abstract] ABSTRACT: We calculated the photon path distribution (PPD) in a scattering medium based on a theoretical analysis, which utilizes the relationship between the photon intensity and photon pathlength. This PPD is defined by local photon pathlengths for photons having total pathlengths of l between the light input points and detection points. The PPD of photons that consist of the impulse response at time t (= l/c) was calculated for a 2-D model. Precise analysis of photon migration in the scattering medium is essential in order to carry out image reconstruction of diffuse optical tomography (DOT). We show the PPD at time t (the total pathlength l = ct) and demonstrate its effectiveness. Our method for describing photon migration is intuitive and allows finding weight functions in DOT.
[show abstract][hide abstract] ABSTRACT: Our newly developed 64-channel time-resolved optical tomographic imaging system using near-infrared light enables us to obtain a quantitative image of hemoglobin concentration changes associated with neuronal activation in the human brain [H. Eda, I. Oda, Y. Ito, Y. Wada, Y. Oikawa, Y. Tsunazawa, M. Takada, Y. Tsuchiya, Y. Yamashita, M. Oda, A. Sassaroll, Y. Yamada, M. Tamura, Multi-channel time-resolved optical tomographic imaging system, Rev. Sci. Instrum., 70 (1999) 3595–3602]. Here, we used this optical imaging system to demonstrate that the backward digit span (DB) task activated the dorsolateral prefrontal cortex (DLPFC) of each hemisphere more than the forward digit span (DF) task in healthy adult volunteers, and higher performance of the DB task was closely related to the activation of the right DLPFC. These results suggest that visuospatial imagery is a useful strategy for the DB task. Optical tomography described here is a new modality of neuropsychological studies.
Cognitive Brain Research 07/2000; · 3.77 Impact Factor
[show abstract][hide abstract] ABSTRACT: Based on the microscopic Beer-Lambert law, two practical time-integrated spectroscopy (TIS) methods, called dual-wavelength spectroscopy method, and dual-wavelength and dual-site spectroscopy method, are described to determine the absolute concentration of an absorber in variously shaped turbid media. We demonstrate, for the first time, the validity of the TIS methods by means of experiments in which the absolute concentrations of an absorber in a tissue-like phantom were determined with errors less than several percent. The advantages and disadvantages of both methods are also discussed.
Japanese Journal of Applied Physics 01/1998; 37:2724-2727. · 1.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: We propose a new algorithm for optical computed tomography to determine the concentrations of absorber in turbid media such as human tissue. Our method does not require the measurement of a reference phantom, so that it is free from significant errors caused by geometric and structural differences between the target and reference media. We use an imaginary reference medium for which the optical properties are specified by the average or quasi-average values measured for the real target medium. Since we can calculate the weight function and re-emission for such an imaginary medium, tomographic images can be reconstructed based on the difference in values measured for the target medium and determined for the imaginary reference. The validity of our method was confirmed by measuring an 80-mm-diameter cylindrical, tissue-like phantom containing three different absorbers. The image quality such as image distortion and the capability for quantifying the concentrations of absorber are also discussed.
Japanese Journal of Applied Physics 01/1998; 37:2717-2723. · 1.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: The mean path length is a key parameter in the study of light propagation in turbid media such as living tissues. In this paper, we propose a simple subtraction method for determining the mean path length traveled by photons in turbid media. The method is based on the fact that the mean time delay (i.e., the center of gravity) of the measured re-emission profile is the sum of the mean time delays of the instrumental function (i.e., the impulse response of the measuring system) and the impulse response of a highly scattering medium. Using this method, the mean path length can be calculated quickly and accurately without the need for performing deconvolution. The theory, computer simulation and experimental demonstration are described.
Japanese Journal of Applied Physics 01/1998; 37:700-704. · 1.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: A simple expression is proposed to describe the dependence of the mean pathlength on scattering properties. Based on this expression and the microscopic Beer–Lambert law, a dual-wavelength time integrated spectroscopy (TIS) method in which the influence of wavelength dependence of scattering properties on both mean pathlength and intensity is taken into consideration, is developed to determine the absolute concentration of an absorber in highly scattering media. The validity and the accurate performance of the method are well demonstrated by measuring the transmission through a slab-like phantom and reflection from a semi-infinite phantom. In both cases, with a single equation, the absorber concentrations were determined within errors of a few percent.