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Biomedical subjects

I Kanno

Publications and source records attributed to I Kanno.

At least 91 records · Page 5Linked to original sources
PubMed1993

Cerebral glioma: evaluation with methionine PET.

The authors examined 50 patients with cerebral glioma with use of positron emission tomography (PET) and L-[methyl]-[11C]methionine to assess the grade of malignancy and the extent of cerebral glioma. Carbon-11 methionine was highly accumulated in the lesion in 31 of 32 patients with high-grade glioma and 11 of 18 patients with low-grade glioma. The rate of uptake of C-11 methionine in high-grade glioma was significantly higher than in low-grade glioma (P < .001). However, in individual cases it was difficult to evaluate the grade of malignancy only from the degree of C-11 methionine accumulation. In most cases, the area of increased accumulation of C-11 methionine did not correspond to the abnormalities seen at computed tomography (CT). Surgical intervention confirmed that methionine PET delineated the extent of cerebral glioma more clearly than did CT. The authors concluded that methionine PET has greater utility in assessing the extent rather than the grade of malignancy of cerebral glioma.

Adolescent↗
PubMed1993

Subarachnoid hemorrhage: evaluation with MR imaging.

Thirty-seven magnetic resonance (MR) examinations were performed at 0.5 T in 33 patients with subarachnoid hemorrhage (SAH) caused by a ruptured aneurysm. Images were obtained 2 hours to 75 days after the ictus. Twenty-four proton-density-weighted (long repetition time [TR], short echo time [TE]) images were obtained in the acute stage (< 72 hours after the ictus) of SAH; SAH was hyperintense to brain parenchyma and cerebrospinal fluid in all cases. The detectability of acute SAH on T1- (short TR, short TE) and T2- (long TR, long TE) weighted images was 36% and 50%, respectively. In the subacute and chronic stages (> 3 days after the ictus), the detectability of SAH on T1-, T2-, and proton-density-weighted images was 73%, 31%, and 83%, respectively. Although computed tomography is still the modality of choice for evaluating acute SAH, the authors emphasize that even acute SAH can be reliably demonstrated with MR imaging with the appropriate parameters.

Adult↗
PubMed1993

[A new method for quantitative measurement of rCBF using graphic plot analysis: application to 123I-IMP dynamic study].

To estimate regional cerebral blood flow (rCBF) using the dynamic data, a new graphic plot analysis is proposed. By assuming a two-compartment model for the tracer kinetics, we derived the linear relationship as Y(t) = 1/K1 + theta t, where Y(t) is the ratio of time-integrated blood activity to brain tissue activity, t is the scan time, and theta is a proportional constant. A plot of Y(t) against the scan time t yields a straight line and the y-intercept of the line represents the value of inverse rCBF K1. This method was applied to five normal subjects with N-isopropyl-p(123I)iodoamphetamine. The mean value of K1 in the gray matter was 42.1 +/- 6.8 ml/100 g/min. We also produced the rCBF images within a few seconds using the present method. The present graphical method gives a reliable and rapid estimation of rCBF.

Amphetamines↗
PubMed1993

A new graphic plot analysis for cerebral blood flow and partition coefficient with iodine-123-iodoamphetamine and dynamic SPECT validation studies using oxygen-15-water and PET.

To estimate regional cerebral blood flow (rCBF) and brain-blood partition coefficient (lambda) using a dynamic measurement, a new graphic plot analysis is proposed. By assuming a two-compartment model for tracer kinetics, we derived the linear relationship as Y(t) = K1 - k2 X(t), where Y(t) is the ratio of brain tissue activity-to-time-integrated arterial blood activity and X(t) is the ratio of time-integrated brain tissue activity-to-time-integrated arterial blood activity. A plot of Y(t) against X(t) yields a straight line and the y- and x-intercept of the regression line represent rCBF (K1) and lambda, respectively. The slope is a washout constant (-k2). This method was applied to 14 subjects with N-isopropyl-p-iodine-123 iodoamphetamine ([123I]IMP). The mean values of K1 and lambda for normal subjects were 41.3 +/- 6.7 ml/100 g/min and 29.6 +/- 6.5 ml/g, respectively, in the gray matter. A comparative study with positron emission tomography (PET) using an H2(15)O autoradiographic method revealed good correlation between IMP K1 and PET rCBF [r = 0.822; K1 = 0.842 rCBF + 0.030 (ml/g/min)]. The values of K1 using the graphical method were in excellent agreement with those using a nonlinear least-squares fitting technique (r = 0.992 for K1; r = 0.941 for lambda). The estimated K1 values in the graphical method were not changed when scanning times were varied. We conclude that a two-compartment model is acceptable for IMP kinetics within a scan time of 60 min. The graphical method gives a reliable and rapid estimation of rCBF when applied to dynamic data.

Amphetamines↗
PubMed1992

A convenient method for regional monoamine oxidase-A determination by [14C]clorgyline autoradiography.

The availability of clorgyline for regional monoamine oxidase-A (MAO-A) determination was examined using [14C]clorgyline in rat. [14C]Clorgyline was synthesized by the methylation reaction of N-desmethyl-clorgyline and [14C]methyliodide in dimethylformamide with high radiochemical yield. The MAO-A distribution map by autoradiography correlated with that by histochemical technique and its quantity was consistent with the calculated MAO-A amount based on previous reports. The combination of labeled clorgyline and autoradiographic technique will promise the quantitative measurement of regional MAO-A distribution.

Animals↗
PubMed1992

[Phenylalanine transport in the living human brain by a dynamic PET of L-[2-18F]-fluorophenylalanine].

The transport kinetics of L-[2-18F]-Fluorophenylalanine in the human brain were studied in one normal subject and 6 patients with brain tumor using a dynamic positron emission tomography. The tracer kinetics from blood to brain were described by two compartment model with K1 (influx) and k2 (efflux). The rate constants in normal brain tissue and tumor tissue were K1 = 0.045 ml/g/min, k2 = 0.078 ml/g/min and K1 = 0.122 ml/g/min, k2 = 0.102 ml/g/min, respectively. The Michaelis-Menten constants (Kt and Tmax) for phenylalanine transport in the normal cortex were graphically estimated. The estimated Kt was 35 nmol/ml, whereas the Tmax varied with cerebral blood flow.

Biological Transport↗
PubMed1992

Cerebral blood flow and glucose metabolism measurements in a patient surviving one year after carbon monoxide intoxication.

A 29-yr-old woman was studied for 1 yr after acute carbon monoxide intoxication following an attempted suicide by inhalation of automobile exhaust fumes. The patient demonstrated impaired responsiveness to stimuli without any specific neurological deficits for 1 yr after carbon monoxide intoxication. Repeated brain magnetic resonance imaging consistently displayed only bilateral globus pallidus lesions, but no lesions in either deep white matter or cerebral cortex. Position emission tomography measurements of regional cerebral blood flow, and glucose utilization rate were made in this patient at 6 mo and 1 yr following carbon monoxide intoxication. Impairment of both blood flow and glucose metabolism were found not only in the basal ganglia but also in morphologically normal frontal cortex. The decrease in glucose utilization in the frontal cortex was greater than that in the basal ganglia. During the period of 6 mo to 1 yr, blood flow and glucose metabolism in the basal ganglia recovered to the normal range. In the frontal cortex, however, blood flow and glucose metabolism remained approximately 20% lower than the normal mean values. This prolonged dysfunction in the frontal cortex may therefore be responsible for the impaired responsiveness of the subject.

Adult↗
PubMed1992

[Arterial clearance and cerebral uptake of Tc-99m ECD in patients with cerebrovascular disease compared with PET].

Technetium-99m ethyl cysteinate dimer (ECD) has recently developed for SPECT imaging in assessment of cerebral perfusion. We evaluated the arterial blood clearance and the regional brain uptake of Tc-99m ECD compared with the regional CBF measured by PET in patients with cerebrovascular disease. Nine patients with diagnosis of cerebral ischemic disorders (N = 7) and cerebral hemorrhage (N = 2) were studied. PET study was performed with HEADTOME IV by O-15 steady state inhalation method. Immediately after the PET study, 555-740 MBq (5-20 mCi) of Tc-99m ECD was injected intravenously. After injection arterial blood sampling was performed sequentially, and we separated lipophilic fraction from whole blood using ethyl acetate in two cases. The SPECT imaging with Tc-99m ECD (ECD-SPECT) was started 5 min (first imaging) and 60 min (second imaging) after the administration using a high resolution ring type SPECT system (HEADTOME II). Several ROIs were placed on practically the same anatomical location on both SPECT and PET images. Clearance of the tracer in arterial whole blood and lipophilic fraction was rapid. Concerning to the distribution pattern of ECD-SPECT images there was no differences between the 1st imaging and the 2nd imaging, although about 15% of diffuse decrease of Tc-99m ECD uptake was shown in the 2nd images. The brain distribution of ECD-SPECT was comparable to the pattern of CBF image by PET. The regional relative counts of ECD-SPECT corresponded closely to the CBF value by PET, but it was no linear correlation between brain uptake of ECD-SPECT and PET-CBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

A new approach of weighted integration technique based on accumulated images using dynamic PET and H2(15)O.

We developed a new technique of weighted integration for the measurement of local cerebral blood flow (LCBF) and the blood-tissue partition coefficient (p) using dynamic positron emission tomography (PET) and H2(15)O. The weighted integration in the new technique is carried out on the equation of the first time integration of the Kety-Schmidt differential equation. Practically, serially accumulated images with sequentially prolonged accumulation times are weighted by two arbitrary functions. The weighting functions do not have to be differentiated because of the exclusion of the differential term in the starting equation. Consequently, the method does not require data at the end of the scan. The technique was applied to H2(15)O dynamic PET performed on four normal subjects, and was verified to provide a better signal-to-noise ratio than the previously developed integrated projection (IP) technique. Computer simulations were carried out to investigate the effects of statistical noise, tissue heterogeneity, and time delay and dispersion in arterial input function. The simulation showed that the new technique provided about a 1.4 times lower statistical error in both LCBF and p at 50 ml 100 g-1 min-1 compared to the IP technique, and it should be noted that the new technique was less sensitive to the shape of the weighting functions. The new technique provides a new strategy with respect to the statistical error for estimation of LCBF and p.

Adult↗
PubMed1991

[The quantitative evaluation of myocardial blood flow and myocardial FDG uptake in the infarcted lesions with Q-wave and without Q-wave determined by O-15 water, FDG and PET].

Cardiac PET elicits an accurate relationship between myocardial blood flow (MBF) and tissue viability, which is evaluated by myocardial FDG uptake (MFU). To differentiate reversible tissue from necrotic tissue after the ischemic event, we from necrotic tissue after the ischemic event, we measured absolute MBF and MFU in patients with myocardial infarction. The MBF obtained by O-15 water and dynamic PET was accurately corrected by employing a tissue fraction (a) for the partial volume effect, including wall-motion effect. MFU was also corrected by using the tissue fraction. The subjects consisted of 5 patients with non-Q-wave infarction and 7 patients with Q-wave infarction. The regions of interest were selected from the infarcted area, each corresponding to regions with Q-wave or non-Q-wave. The MBFs in regions with Q wave (0.36 +/- 0.14 ml/min/g) were lower than those without Q wave (0.74 +/- 0.29 ml/min/g) (p less than 0.005). MFUs in regions without Q-wave (0.061 +/- 0.028) were higher than those with Q-wave (0.038 +/- 0.017) (p less than 0.05). The highest threshold of MBF in regions where Q-wave was detected was 0.55 ml/min/g. It is concluded that we will able to find the threshold of electrophysiological dysfunction in the infarcted region with this method.

Aged↗
PubMed1991

Rapid measurement of cerebral blood flow with positron emission tomography.

The intravenous administration of H2(15)O makes possible the quantitative evaluation of regional changes in cerebral blood flow (CBF) during various neuronal activations in man. Many variations on this technique have been proposed. We have compared bolus and slow administration procedures and short and long scan lengths. For a short scan period this study suggests that the bolus injection procedure (with a scan length of 60-120 seconds) provides better CBF count statistics and less sensitivity to errors in the input function than the slow infusion procedure. For a long scan length (greater than 3 min) the slow infusion procedure is recommended. Continuation of H2(15)O infusion allows prolongation of the scan length, which enables us to obtain sufficient CBF statistics (the statistical error may be negligibly small if a sufficient amount of H2(15)O is infused). Another advantage of the slow infusion method may be related to the fluctuation of CBF during the scan period. If CBF fluctuates during this period the slow infusion procedure is expected to provide an average estimate of CBF, whereas the bolus injection procedure provides an estimate (an average over 10 seconds) of CBF which is more sensitive to short-term variations. The feasibility of using 15O2 inhalation to measure regional CBF has also been investigated. By means of a dynamic H2(15)O scan which measures the regional distribution volume of water and a static C15O emission scan which measures blood volume prior to the 15O2 scan, both CBF and cerebral metabolic rate for oxygen (CMRO2) have been accurately measured by the 15O2 scan for various physiological conditions. The application of this technique in a human study confirmed the uncoupling of CBF and CMRO2 during motor and visual activation.

Autoradiography↗
PubMed1991

Optimization of H2(15)O-CBF method for higher signal-to-noise ratio.

We described theoretical principle and data analysis for PET study using intravenous H2(15)O for measurement of cerebral blood flow (CBF) with emphasis on stimulation study for psychophysiological test. In order to improve signal-to-noise (S/N) ratio in CBF images, we optimized the scan procedures and data analysis. We determined optimal scantime of autoradiographic image to provide minimum S/N ratio as to 90 through 120 sec. Increase of full-width at half-maximum (FWHM) of smoothing filter did reduce the image noise (standard deviation, SD) more rapidly than the partial volume effect. Phantom experiment showed a tendency that a larger FWHM provided a higher statistical t-value.

Brain↗
PubMed1991

Blood sampling devices and measurements.

Quantitative positron emission tomography requires the determination of the tracer concentration in arterial plasma or full blood as a function of time. This defines the experimental input function. The model prediction, with which the positron camera regional time-activity curves are compared, is given by the experimental input function convoluted with the model. This paper reviews different strategies for determining the input function, invasive techniques, such as manual blood sampling and the use of automated blood sampling systems, and non-invasive techniques. The importance of corrections is discussed, such as accurate cross-calibrations of the different detectors used in quantitative PET and corrections for differences in time phase between the regional PET time-activity curves and the input function. We also report on the use of a PET system in non-invasive determinations of the input function. By imaging the neck region the time-activity curve of the carotid arteries can be obtained. The PET time-activity curves of the carotid arteries are in good agreement with a conventional experimental input function determined from the radial artery with an automated blood sampling system. However, PET time-activity curves of the radial arteries can not be used without a deconvolution since the resistance in the intact radial artery causes dispersion compared to the input function obtained by invasive methods.

Blood Specimen Collection↗
PubMed1991

Optimal scan time of oxygen-15-labeled water injection method for measurement of cerebral blood flow.

We investigated the optimal scan time for obtaining the maximal signal-to-noise (S/N) ratio in cerebral blood flow (CBF) measured by PET imaging following 15O-water bolus injection. We performed sequential measurements with dynamic scans of six subjects injected at rest while listening to white noise. Each dynamic data set was edited into images corresponding to different scan times and were calibrated to CBF images by the table look-up method. For each scan time, we evaluated a pixel-by-pixel standard deviation of the CBF for sequential measurements. The S/N-ratio of CBF in the gray matter was 10.2 +/- 1.7 and 13.6 +/- 2.9 at a 40 and 120 sec scan time, respectively. The gain of the 120-sec over 40-sec scan time corresponds to an 80% increase in the number of trials to reach the same S/N-ratio in a stimulation-activation study. The simulation study supported the results, in which the maximal S/N-ratio of the CBF was demonstrated to be 90 and 120 sec at a CBF of 80 and 60 ml/100 ml/min, respectively. It is concluded that the optimal scan time of the 15O-water bolus injection method is in the interval from 90 to 120 sec.

Brain↗
PubMed1991

[New analysis algorithm for regional cerebral blood flow and partition coefficient with dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine: graphical plot method].

We developed a new analysis algorithm based on multiple-time graphical plot to estimate the regional cerebral blood flow and partition coefficient using dynamic SPECT and N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). By assuming the 2-compartment model of the kinetic for 123I-IMP, we derived a linear relationship between the ratio of the tissue activity concentration at the times to the time-integral arterial concentration at the respective times (formula; see text) and the ratio of the time-integral tissue concentration to the time-integral arterial concentration (formula; see text), and demonstrated that the Y-intercept and X-intercept of the plot line represent the regional cerebral blood flow (K1) and partition coefficient (lambda), respectively. The slope of the line represents a clearance constant k2. The present method was applied to data on four normal subjects measured by dynamic SPECT. Values of the K1 and lambda for the gray matter were obtained 40.8 +/- 6.5 ml/100 g/min and 28.8 +/- 5.3 ml/g, respectively, and the corresponding values for the white matter were 29.1 +/- 4.7 ml/100 g/min and 28.1 +/- 7.1 ml/g. The new method enabled a rapid estimation of both K1 and lambda.

Algorithms↗