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Biomedical subjects

T Togawa

Publications and source records attributed to T Togawa.

At least 55 records · Page 3Linked to original sources
PubMed1996

The effect of steroid on thallium-201 uptake by malignant gliomas.

In order to assess the effect of steroid on thallium-201 uptake by glioma, 201Tl single-photon emission tomography was performed before and after steroid administration in four patients with recurrent malignant glioma. After steroid administration the 201Tl index, expressed as the ratio of 201Tl uptake in the tumour to that in the contralateral cerebral hemisphere, was 0.77+/-0.11 of the value before steroid (mean+/-SD: P<0.05 by paired t test). The 201Tl index has been used as a possible indicator for the differentiation of malignant gliomas from relatively benign tumours or radiation necrosis. The present results indicate that the effect of steroid has to be taken into account when semi-quantitative analysis, e.g. by means of the 201Tl index, is used in patients with brain tumours.

Antineoplastic Agents, Hormonal↗
PubMed1996

Quantifying brain tumor blood flow by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine super-early SPECT.

Regional cerebral blood flow was quantitatively measured in 6 patients with brain tumor by the microsphere model with N-isopropyl-p-[123I]iodoamphetamine (IMP) "super-early" single photon emission computed tomography (SPECT) images obtained 4-6 min after IMP injection with a three-head rotating gamma camera. The ratio of radioactivities (counts/pixel/min) in the "early" SPECT images (taken 25-55 min after IMP injection) to the "super-early" images of the brain tumors was 1.47 +/- 0.13 (mean +/- SD, n = 6), which was significantly lower than the ratio in the normal cerebral cortices (1.93 +/- 0.25) (p < 0.01). This indicates faster clearance of IMP from the tumor tissue than that from the normal brain tissue. Blood flow values for the brain tumors obtained by the microsphere model based on the "super-early" SPECT images were 39.3 +/- 12.4 ml/100 g/ min, which was similar to the blood flow values for normal gray matter and in agreement with previous studies with positron emission tomography.

Adult↗
PubMed1996

[Diagnostic accuracy of 201T1 SPECT.MRI in brain diseases and inter-reader variance of diagnostic performance].

Fifteen-four studies of 201T1 brain tumor SPECT were independently interpreted by 9 nuclear medicine physicians with and without reference magnetic resonance images in 2 separate sessions to define an effect of referring images, and inter-observer variations. The physicians were requested to detect foci of abnormal deposits, and to discriminate whether they were malignant or not according to 5-grade scaling of subjective diagnostic confidence. Receiver-operating characteristics (ROC) analysis was performed. Mean sensitivity for presence of lesions (SEP), and sensitivity and specificity for malignancy of 201T1 SPECT were 84, and 53 and 55%, which were changed to 94, and 74 and 55% after referring to the MR images. The SFP was significantly improved (p < 0.05), but sensitivity and specificity for malignancy, assessed by areas under the ROC curves, were not significantly improved. Inter-observer variation of the SFP was significantly reduced with addition of the referring MR images. Cerebral lobar localization of lesions by SPECT showed great inter-observer variations (true localization ranged from 30 to 68.4%). It is concluded that 201T1 brain tumor SPECT has moderate sensitivity and specificity for malignancy, which is not improved by addition of anatomical reference images, that additional MR images reduce inter-observer variation of confidence on lesion presence, and that SPECT localization of lesions has great inter-observer variations.

Adolescent↗
PubMed1995

Measurement of the thermal inertia of the skin using successive thermograms taken at a stepwise change in ambient radiation temperature.

Skin thermal properties are difficult to measure in vivo in the steady state because there is a constant temperature gradient across the skin surface. However, measurement of skin thermal properties is postulated in quantitative evaluation for thermographic observation. In this study, imaging of the thermal inertia of the skin was attempted by thermographic measurements at a stepwise change in ambient radiation temperature achieved by quickly switching two hoods maintained at different temperatures. Using this technique, a total of 65 thermograms were sequentially recorded at intervals of 0.5 s beginning 2 s before the stepwise change. The image of skin thermal inertia was estimated by applying statistical curve fitting at each pixel of the thermograms. In addition, the emissivity and true temperature of the skin were also determined, together with thermal inertia, in a single measurement. Measurements were made at different sites on 10 subjects. The average values of thermal inertia of normal skin were scattered throughout a range from 1.4 x 10(3) to 2.1 x 10(3) W s1/2 m-2 K-1. Investigations of the relationship between skin blood flow and thermal inertia were also made by imaging thermal inertia when skin blood flow was changed by applying a vasodilator or vasoconstrictor on the skin surface. In a comparison with the data measured by laser Doppler flowmetry, the average slope of skin blood flow versus thermal inertia was 2.88 x 10(-4) V per W s1/2 m-2 K-1, and the thermal inertia of the skin with no blood flow was 1.03 x 10(3) W s1/2 m-2 K-1. The results also show an almost linear correlation between skin blood flow and thermal inertia in each individual, but inter-individual differences were also observed. The results suggest that skin blood flow distribution can be estimated by non-contact imaging of thermal inertia.

Humans↗
PubMed1995

Improvement of imaging of skin thermal properties by successive thermographic measurements at a stepwise change in ambient radiation temperature.

Imaging of skin thermal properties was attempted by successive thermographic measurements of the skin surface with a stepwise change in ambient radiation temperature. In order to produce the stepwise change in ambient radiation temperature, two hoods maintained at different temperatures, 20 degrees C and 60 degrees C, were mechanically switched. A total of 65 thermograms were taken from 2 s before to 32 s seconds after the hood switching. Images of skin emissivity, emissivity-corrected skin temperature and thermal inertia were obtained by least-squares fitting at each pixel of 64 thermograms. Measurements were performed on the forehead, cheek, forearm, palm and back of the hand of 10 healthy male subjects. Differences in emissivity between sites and subjects were insignificant. Significant differences were observed in thermal inertia values between sites. Great improvements in the imaging of thermal inertia have been achieved by applying least-squares fitting to 64 thermograms instead of by computations from only two thermograms as in the previous study. Non-contact measurement and visualization of skin thermal properties are significant advantages of this method.

Adult↗
PubMed1995

[A study on thallium-201 SPECT in brain metastases of lung cancer: with special reference to tumor size and tumor to normal brain thallium uptake ratio].

Thallium-201 brain SPECT was performed on 20 patients with brain metastases of lung cancer using a three-head rotating gamma camera and the effect of tumor size on tumor detectability and tumor to normal brain thallium uptake ratio (T/N ratio) was studied. Among 71 metastatic lesions, only 9 (22.5%) of 40 lesions of 13 mm diameter or below and 31 (100%) of 31 lesions of 14 mm diameter or above could be detected in this study. There was a significant correlation between T/N ratio and tumor size (r = 0.75, p < 0.001). The greater the metastatic lesion, the higher the T/N ratio. Even among the tumors in a single patient with multiple brain metastases, there was a significant linear correlation between tumor size and T/N ratio (r = 0.96, p < 0.01). In this patient, T/N ratio varied by the tumor size and these differences in T/N ratios were thought to be based on the partial volume effect. However, T/N.d which was a parameter corrected by tumor diameter (d) showed a constant value regardless of tumor size. The present results showed that T/N ratio, which was usually believed to quantitate the malignancy grade of brain tumor, was affected by tumor size and that more accurate parameter could be obtained by the correction of T/N ratio by tumor size.

Adenocarcinoma↗
PubMed1994

Non-contact imaging of thermal properties of the skin.

Non-contact measurement of thermal properties of the skin was performed by using a thermovision camera and a mechanical system that provides a step change in ambient radiation temperature. A hood maintained at 20 degrees C was initially placed so as to cover the object surface towards which a thermovision camera was directed. Then the hood was quickly replaced by another hood maintained at 40 degrees C. Thermograms before, immediately after and 20 s after switching the hoods were taken. Then the image of emissivity was computed from thermograms taken before and immediately after hood switching, and the emissivity-corrected thermograms were computed by using the emissivity value obtained at each pixel. The images of the square root of the product of thermal conductivity, density and specific heat were computed from thermograms taken immediately after and 20 s after hood switching. While images of the emissivity obtained and the thermal parameter defined above contained significant noise, differences in these quantities between sites could be clearly demonstrated.

Humans↗
PubMed1993

Determination of bound sulfur in serum by gas dialysis/high-performance liquid chromatography.

A sensitive high-performance liquid chromatography (HPLC) method has been developed for the determination of bound sulfur in mammalian serum. In this work, bound sulfur is defined as divalent sulfur that is easily liberated as sulfide by reduction with dithiothreitol. Released sulfide was treated by flow gas dialysis and converted into a fluorescent derivative, thionine, through the reaction with p-phenylenediamine and ferric ion. Thionine was then determined by HPLC using fluorometric detection. The calibration curve for bound sulfur is linear in the range from 0.1 to 10 microM, and the sensitivity of this method allows detection of less than 10 nM bound sulfur (0.5-ml sample). Recoveries of low-molecular-weight and high-molecular-weight bound sulfur added to human serum at 1.0-5.0 microM levels averaged between 94 and 101%. The proposed method was applied to the determination of bound sulfur in human and various animal sera. The mean concentration in normal human serum was 1.16 +/- 0.09 microM for males (n = 5) and 1.07 +/- 0.18 microM for females (n = 5). The mean concentrations ranged from 1.55 to 6.18 microM in animal sera. The form of the sulfur bound in serum was also discussed.

Animals↗
PubMed1993

Optimization of Butterworth filter for brain SPECT imaging.

A method has been described to optimize the cutoff frequency of the Butterworth filter for brain SPECT imaging. Since a computer simulation study has demonstrated that separation between an object signal and the random noise in projection images in a spatial-frequency domain is influenced by the total number of counts, the cutoff frequency of the Butterworth filter should be optimized for individual subjects according to total counts in a study. To reveal the relationship between the optimal cutoff frequencies and total counts in brain SPECT study, we used a normal volunteer and 99mTc hexamethyl-propyleneamine oxime (HMPAO) to obtain projection sets with different total counts. High quality images were created from a projection set with an acquisition time of 300-seconds per projection. The filter was optimized by calculating mean square errors from high quality images visually inspecting filtered reconstructed images. Dependence between total counts and optimal cutoff frequencies was clearly demonstrated in a nonogram. Using this nomogram, the optimal cutoff frequency for each study can be estimated from total counts, maximizing visual image quality. The results suggest that the cutoff frequency of Butterworth filter should be determined by referring to total counts in each study.

Brain↗
PubMed1993

Visualization of nasopharyngeal carcinoma with Tl-201 chloride and a three-head rotating gamma camera SPECT system.

Tl-201 SPECT was performed on 12 patients with nasopharyngeal carcinoma (NPC) by means of a three-head rotating gamma camera to evaluate whether or not Tl-201 SPECT was useful and reliable for assessing the tumor viability of NPC. Tl-201 clearly accumulated in the tumor in 3 patients before radiation treatment and increased Tl-201 uptake by the lesion ceased after the treatment. Three of 9 patients who were followed up after radiotherapy developed apparent local recurrence and Tl-201 SPECT clearly visualized these recurrent lesions. Tl-201 SPECT was very useful for assessing the tumor response to irradiation and for detecting local recurrent tumor. A high resolution SPECT system employing Tl-201 chloride is a new reliable and accurate diagnostic tool for the assessment of NPC.

Adult↗
PubMed1993

Usefulness of bone SPECT of the cervical spine: with special reference to separate visualization of the trachea and thyroid cartilage.

We applied bone SPECT for the examination of the cervical spine. A three-head rotating gamma camera SPECT system was employed for this study. The SPECT image disclosed 42.7% of abnormal accumulations in the skeleton not seen with planar imagings. SPECT could separately visualize the trachea and thyroid cartilage and also provided interpretation of abnormality in the anterior part of the vertebral body being difficult with planar imagings only. The trachea cartilage was seen in 55.4% and the thyroid cartilage was seen in 47.3% of patients with anterior neck density in planar imagings. SPECT clarified that marked cervical curvature and diffuse high uptake by the skeleton might cause high intensity of the anterior neck in planar imagings in the case of non-pathological change. We concluded that bone SPECT is a useful diagnostic tool in detecting occult lesion in the skeleton and to rule out extraskeletal accumulations in examination of the cervical spine.

Adult↗
PubMed1993

Demonstration of abnormal perfusion in the pons with high resolution SPECT and technetium-99m HMPAO in a patient with acoustic neuroma.

We detected a regional defect in the pons with ipsilateral cerebellar hypoperfusion in a patient with acoustic neuroma by brain SPECT with 99mTc HMPAO. A high spatial resolution SPECT system with three detectors equipped with fan-beam collimators was employed. This is the first report of a defect in the brainstem being visualized by perfusion SPECT and this method could make it possible to clarify the cause of a remote effect on the cerebellar perfusion by injury to the brainstem.

Cerebellum↗
PubMed1993

A system for monitoring temperature distribution in bed and its application to the assessment of body movement.

For the assessment of body movements during sleep, a system for monitoring the temperature in bed was developed. The system consists of 16 temperature sensors and a data logger with a memory card. Fifteen of the temperature sensors were arranged in line 6 cm apart on a flat cable. The temperatures at these 15 points in the bed, and the room temperature measured by the additional sensor, were stored on the memory card at predetermined intervals. The data were transferred into a microcomputer and analysed. Changes in posture and body movement were recognizable from the changes in the temperature profile, and well visualized using a three-dimensional display of the successive temperature profiles in the bed. The time of body movement was estimated from the derivative of the temperature profile. Comparison between this estimation and the video recording showed good agreement. The linear arrangement of the sensors provides a high-resolution temperature profile during sleep.

Adult↗
PubMed1992

Ambulatory oxygen uptake measurement system.

An apparatus for monitoring prolonged measurement of oxygen uptake without discomfort has been developed. The system is based on the open flow-through principle. The subject wears a hood through which air is drawn by an exhaust blower. Oxygen concentration is kept constant by a servo-controlled blower, so that flow rate is essentially proportional to oxygen uptake. The flow rate of the main stream is measured by a time-of-flight flowmeter located in the exhaust hose. Oxygen concentration is measured by a limiting-current oxygen sensor. The signals representing flow rate and oxygen concentration are digitized and stored in a memory. All of the equipment is assembled in a small package (wt = 3 kg) which the subject carries on his back. The memory chip is removed from the portable device after each experiment. Data are transferred from the memory to a microcomputer and then an oxygen uptake trend is estimated. Response of the system to a step input is about 30 s. Compared with a commercially available oxygen monitoring system (Magna 88, P. K. Morgan Ltd., Rainham, UK), the maximum difference was 0.15 L/min within an oxygen uptake range of 0.25-2.3 L/min. Thus, the measurements made with our portable device agree with the results obtained using the conventional method.

Adult↗
PubMed1992

High performance liquid chromatographic determination of bound sulfide and sulfite and thiosulfate at their low levels in human serum by pre-column fluorescence derivatization with monobromobimane.

A sensitive and specific high performance liquid chromatographic method for the determination of sulfide, sulfite, and thiosulfate was established. Inorganic sulfur anions were converted into fluorescent derivatives with monobromobimane. The derivatives were separated on a coupled column chromatography with a reversed-phase octadecyl silica column connected with a weakly basic anion exchanger column by isocratic elution with acetic acid solution (pH 3)-acetonitrile (13:3, v/v) containing 25 mM NaClO4. The method was applied to the determination of bound sulfide and sulfite and thiosulfate in normal human serum. Thiosulfate could be determined directly by use of an ultrafiltered sample. For the determination of bound sulfide and sulfite, the pretreatment step with continuous flow gas dialysis was effective for the sample after releasing sulfide and sulfite by reduction with dithiothreitol. The limits of quantification by the present method were 0.05 microM for thiosulfate, 0.5 microM for bound sulfide, and 0.2 microM for bound sulfite.

Bridged Bicyclo Compounds↗
PubMed1992

Comparison of laser Doppler fluxmetry and the thermal diffusion method of measuring skin blood flow with hydrogen clearance.

Laser Doppler fluxmetry (LDF) and the thermal diffusion method (TDF) were compared with the hydrogen clearance method in ten rabbit ears. The LDF signal followed the rapid change in blood flow caused by aortic occlusion and the signal obtained by TDF showed a time delay and the response was less steep compared with the LDF signal. Simultaneous recording showed both methods correlated well with the hydrogen clearance method, but the relationship varied among the studies (the slope 0.0189-0.0967 for LDF, the slope 0.052-0.682 for TDF). Both methods appear to provide a good indicator of the response pattern of blood flow in the region tested. However, variability among the subjects indicates that the quantitative application of both techniques is difficult.

Animals↗