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Biomedical subjects

I Kanno

Publications and source records attributed to I Kanno.

At least 163 records · Page 9Linked to original sources
PubMed1984

Measurement of cerebral blood flow using bolus inhalation of C15O2 and positron emission tomography: description of the method and its comparison with the C15O2 continuous inhalation method.

This article describes a rapid method for the regional measurement of cerebral blood flow using a single breath of C15O2 and positron emission tomography. The technique is based on the bolus distribution principle and utilises a reference table for the calculation of flow. Seven subjects were studied using both this method and the C15O2 continuous inhalation steady-state technique. The single-breath method gave flow values 20% higher than those obtained using the steady-state method. A simulation study was performed in an attempt to define the reasons for the difference between the two techniques. Estimations were made of identified sources of error in the measurement of regional cerebral blood flow using the single-breath technique and compared with results from a similar study previously described for the steady-state technique. However, further comparative studies will be necessary to satisfactorily explain the difference between both techniques.

Adult↗
PubMed1984

[Characteristics of NaI detector in positron imaging device HEADTOME employing circular ring array].

In positron emission computed tomographs employing circular ring arrays of detectors, the performance of the imaging device has been specified ultimately by the characteristics of the detector. The responses of NaI detector were studied when detecting positron annihilation photon (511 keV). The study was mainly by using the NaI detector used in hybrid emission computed tomography (CT) "HEADTOME" we had developed. A series of measurements were carried out positioning two detectors with 40 cm distance and scanning 22Na point source in water. Both detectors was inclined from 0 degrees through 30 degrees to change incident angle of positron annihilation toward crystal face. Energy window was set from 100 to 700 keV. The results were presented as follows: Shortening the crystal length from 7 to 5 cm made sensitivity decrease about 10% and resolution deteriorate about 1 mm (FWHM). As the results of varying the width of the crystal, 20 mm width was optimal at any incident angle. The lead septum between the detectors was the thickness of 4 mm enough to reject multiple detector interactions (crosstalk). Beam mask which was made of lead in order to improve spatial resolution and placed on crystal face worked effectively for incident angles from 0 degrees to 15 degrees but degraded uniformity of spatial resolution from 0 degrees to through 30 degrees.

Sodium Iodide↗
PubMed1982

Tomographic study of regional cerebral blood flow in ischemic cerebrovascular disease by 81mKr intraarterial infusion and HEADTOME.

The single photon mode of a hybrid emission tomograph, HEADTOME, was used to appraise cerebral blood flow (CBF) by the continuous infusion of 81mKr into the internal carotid artery or the ascending aorta. The study was performed on 32 patients with ischemic cerebrovascular disease. The results of the tomographic CBF study were compared with the findings of X-ray computed tomography (CT) and carotid angiography. Twenty-nine patients in the present series showed ischemic areas that correlated better with the localization suggested by the clinical rather than the CT findings. In two patients, CT was negative, whereas the CBF tomogram clearly revealed an ischemic focus. In most of the patients (90.6%), regional ischemia was seen to extend to the normodense brain tissue surrounding the low density areas. Although the method has some limitations, such as its invasiveness, it may be an economical and practical technique for tomographic CBF studies.

Adult↗
PubMed1981

[Measurement of regional cerebral blood flow by 133Xe inhalation method -experimental system and its evaluation of data analysis by simulation study (author's transl)].

Noninvasive measurement of regional cerebral blood flow (rCBF) by 133Xe inhalation and simulation studies of the errors in analyzing 133Xe clearance curves were reported. Our system was based on Obrist's 10 minutes desaturation method after 1 minute inhalation of 185 approximately 222 MBq (5 approximately 6 mCi)/l of 133Xe gas mixed in the air. Clearance curves were simultaneously measured at six location in each hemisphere. End-tidal 133Xe curve used for correction of recirculation was generated from respired air curve. Values for rCBF were calculated by two compartment analysis of the head curves. We evaluated the experimental errors with computer simulation studies. The synthetic head curves were generated with a three compartmental model representing the fast and slow component in the brain and the extracerebral component. The arterial input function used was the end-tidal curves of a typical control subject. The results of computer simulation studies were obtained as follows: F1 that is the flow of the fast compartment in brain and adequate reliability; statistical errors for normal value of F1 (80 ml/100 g/min) were 5% at 30 kcpm; the optimum end point of curve-fitting was 10 approximately 11 minutes after 1 minute inhalation of 133Xe gas; the error due to remaining activities of repreceding study was 3% at the interval of 25 minutes between inhalation.

Cerebrovascular Circulation↗
PubMed1979

Two methods for calculating regional cerebral blood flow from emission computed tomography of inert gas concentrations.

Two methods are described for calculation of regional cerebral blood flow from completed tomographic data of radioactive inert gas distribution in a slice of brain tissue. It is assumed that the tomographic picture gives the average inert gas concentration in each pixel over data collection periods of 30 to 60 sec. In the early picture method a single picture taken during maximum inert gas concentration (by intaarterial injection or by inhalation) is analyzed. In the sequence of pictures method the alterations in local inert gas concentration are followed over time. The proposed methods are implemented using synthetic data of xenon-133 emission computed tomography and some of the difficulties likely to be encountered in practice are stressed.

Cerebrovascular Circulation↗