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The present study aimed to evaluate whether the use of a smoothing filter would improve the image quality in pediatric 99mTc-dimercaptosuccinic acid (99mTc-DMSA) scintigraphy. We retrospectively reviewed 31 kidneys in 16 consecutive pediatric patients aged 10 months to 14 years. The administered dose was calculated using a weight-based method. Two reviewers randomly evaluated the original planar posterior images and smoothing filter image; they assessed image quality and performed defect evaluations. The evaluation of visual image quality yielded significantly better results for the smoothing filter images than for the original images. Although the smoothing filter images were slightly inferior to the original images in terms of edge sharpness, no significant difference was observed in the defect evaluation. We confirmed that 99mTc-DMSA scintigraphy with a smoothing filter yielded reduced image noise, while maintaining defect evaluation performance and improving image quality.

Background. Carotid artery resection has been shown to yield a chance of cure in patients with advanced head and neck carcinoma involving the carotid artery. However, the criteria for the identification of those who are vulnerable to neurologic injury after resection have not been established. Interposition grafting may minimize the risk of neurologic morbidity, although it is technically difficult when there is involvement of the internal carotid artery close to the skull base. Methods. We studied 24 patients with head and neck tumor involvement of the carotid artery. We performed carotid artery resection in 16 of them, including 10 in whom the carotid artery was reconstructed with interposition grafts covered with muscle flaps. When it was thought that the reconstruction would be difficult, positron emission tomography was performed during balloon test occlusion of the internal carotid artery to assess the adequacy of hemispheric collateral blood flow before carotid resection. In one patient with interposition graft, carotid rupture occurred as a result of wound infection, but none of the other patients experienced perioperative death, persistent hemiplegia, or delayed stroke. Result. Twelve patients have survived longer than 8 months, and seven (43.8%) were alive without disease at 12 months after resection, whereas all four patients who could not be treated operatively died within 8 months as a result of local primary tumors. Conclusions. Carotid artery resection is the only therapy offering any potential for cure or palliation. Positron emission tomography is a rapid quantitative means of determining the cerebral blood flow, particularly when resection is planned without reconstruction.

To investigate the effect of the level of baseline cerebral blood flow (CBF) on local CBF augmentation by activation, we have used positron emission tomography to measure regional CBF (rCBF) in 12 normal volunteers with and without photic stimulation during hypocapnia, normocapnia, and hypercapnia. The increase in rCBF in the primary visual cortex by photic stimulation was 10.8 ± 3.1, 18.6 ± 9.3, and 19.5 ± 6.1 ml 100 ml−1 min−1 in hypo-, normo-, and hypercapnia, respectively. The increase was significantly smaller in hypocapnia than in normocapnia ( p < 0.005). The fractional CBF increase caused by the photic stimulation was the same in all breathing conditions. This result indicates that the magnitude of the CBF increase induced by neuronal activity correlates proportionally with the level of baseline CBF.

During an experiment on nocturnal sleep interruption, we observed a unique case of hallucination without sleep paralysis during the sleep-onset REM period in a normal individual. We documented the polysomnogram recorded during this hallucination. The polysomnogram showed a mixed pattern of Stages REM and W, with muscle-tone inhibition, rapid eye movements (REMs), slow eye movements (SEMs), and abundant alpha EEG trains. The blocking of alpha EEG trains by REMs appeared to reflect visual processing similar to that which occurs during waking. This hallucination was distinct from ordinary sleep-onset mentation in that it included strong emotional components and in that the subject simultaneously experienced both hallucinatory mentation and reality contact. This hallucination may resemble sleep paralysis with regard to its physiological and psychological background, and the discrimination of these two phenomena may depend on the subject's own awareness of muscle-tone inhibition.

Concerning vasoreactivity of cerebellar blood flow (CeBF) in patients affected with crossed cerebellar diaschisis (CCD), several controversies have been reported. One is reduced asymmetry of CeBF after acetazolamide administration in 99mTc hexamethylpropyleneamine oxime single-photon emission-computed tomography, and the other is persistent asymmetry with alternation in PaCO2 using the 133Xe clearance method. The purpose of this study is to examine whether CeBF vasoreactivity in the side affected with CCD is the same as that in the unaffected side. We analyzed CeBF during hypocapnia, normocapnia, and hypercapnia performed in 27 patients with cerebrovascular disease (age range, 38 to 73 years; mean age, 62.0 +/- 8.5 years) affected by CCD. CeBF was measured using H2(15)O and positron emission tomography. The CeBF ratio of CCD-affected side to CCD-unaffected side was consistent during the perturbation of PaCO2. This ratio was 0.82 +/- 0.08 for PaCO2 elevation and 0.83 +/- 0.07 for PaCO2 lowering. Both were not significantly different from unity. The percent change of CeBF per millimeter of mercury PaCO2 change was uniform across affected and unaffected sides with CCD. These findings are consistent with our recent findings observed in activated cerebral tissue during photic stimulation.

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.

We reviewed the thoracic vertebra MRI of patients whose chief complaint was dorsalgia (or + lower back dorsalgia). Thoracic vertebra MRI of 103 patients had dorsalgia as the chief complaint mainly or sometimes in 134 (man 61, woman 73) and had led them to consult an orthopaedic specialist. A difference was seen in the cavity diameter under the posterior arachnoid in 103 and 31 which led to MRI scan of the thoracic vertebra. The cavity diameter was equal to or more than 0.55 posterior space, equal to or less than 0.43 abdominal side space. We reviewed the thoracic vertebra MRI of the patients whose the chief complaint was dorsalgia (or lower back dorsalgia). On the thoracic vertebra sagittal T2w MR scans we obtained eccentricities from the center to the thoracic ventral aspect and to the dorsal aspect at the widest diameter of the spinal canal. The eccentricities were calculated as ratios of the diameter of the spinal canal at the maximal occipitofrontal diameter to the dorsal subarachnoid space diameter, and to the ventral subarachnoid space diameter. Spinal cord imaging was done by exclusion to the abdominal side because the cavity diameter under the posterior arachnoid was wide. The ventral root was towed and the dorsal root was assumed to be bent.

As described herein, we propose an unsupervised method for segmentation of magnetic resonance (MR) brain images by hybridizing the self-mapping characteristics of 1-D Self-Organizing Maps (SOMs) and using incremental learning functions of fuzzy Adaptive Resonance Theory (ART). The proposed method requires no operator to specify the representative points. Nevertheless, it can segment tissues (such as cerebrospinal fluid, gray matter and white matter) that are necessary for brain atrophy diagnosis. Additionally, we propose a Computer-Aided Diagnosis (CAD) system for use with brain dock examinations based on case analyses of diagnostic reading. We construct a prototype system for reducing loads on diagnosticians during quantitative analysis of the degree of brain atrophy. Field tests of 193 examples of brain dock medical examinees reveal that the system efficiently supports diagnostic work in the clinical field: the alteration of brain atrophy attributable to aging can be quantified easily, irrespective of the diagnostician.

We propose an objective segmentation method for Magnetic Resonance (MR) images of the brain using self-mapping characteristics of one-dimensional Self-Organizing Maps (SOM). The proposed method requires no operators to specify the representative points, but can segment tissues (such as cerebrospinal fluid, gray matter and white matter) needed for diagnosis of brain atrophy. Doing clinical image experiments, we demonstrate the effectiveness of our method. As a result, we can obtain segmentation results that agree with anatomical structures such as continuities and boundaries of brain tissues. In addition, we propose a Computer-Aided Diagnosis (CAD) system for brain dock examinations based on the use case analysis of diagnostic reading, and construct a prototype system for reducing loads to diagnosticians that occur in quantitative analyses of the extent of brain atrophy. Through field tests of 193 examples of brain dock medical examinees at Akita Kumiai General Hospital, we also present the prospect of efficient support of diagnostic reading in the clinical field because the aging situation of brain atrophy is readily quantifiable irrespective of diagnosticians' expertise.

Using positron emission tomography (PET), cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMR02) were measured in 32 healthy volunteers aged from 27 to 67 years. In bilateral putamen, left supratemporal\ left infrafrontal and left parietal cortices, CMR02 showed a significant decline during aging. The age-related decline of CBF was seen only at the left superior temporal cortex. The mean CMR02 was significantly lower in the elder group (over 51 years old) than in the younger group (under 50 years old), whereas no significant difference in mean CBF between the two groups. The poor correlation of CBF to the age could be explained partly by the fact that CBF is easily influenced by the physiological, psychological and/or environmental factors. The age-related changes of CMR02 were more marked in the association cortices of the left hemisphere than in that of the right hemisphere.

We elicited isolated sleep paralysis (ISP) from normal subjects by a nocturnal sleep interruption schedule. On four experimental nights, 16 subjects had their sleep interrupted for 60 minutes by forced awakening at the time when 40 minutes of nonrapid eye movement (NREM) sleep had elapsed from the termination of rapid eye movement (REM) sleep in the first or third sleep cycle. This schedule produced a sleep onset REM period (SOREMP) after the interruption at a high rate of 71.9%. We succeeded in eliciting six episodes of ISP in the sleep interruptions performed (9.4%). All episodes of ISP except one occurred from SOREMP, indicating a close correlation between ISP and SOREMP. We recorded verbal reports about ISP experiences and recorded the polysomnogram (PSG) during ISP. All of the subjects with ISP experienced inability to move and were simultaneously aware of lying in the laboratory. All but one reported auditory/visual hallucinations and unpleasant emotions. PSG recordings during ISP were characterized by a REM/W stage dissociated state, i.e. abundant alpha electroencephalographs and persistence of muscle atonia shown by the tonic electromyogram. Judging from the PSG recordings, ISP differs from other dissociated states such as lucid dreaming, nocturnal panic attacks and REM sleep behavior disorders. We compare some of the sleep variables between ISP and non-ISP nights. We also discuss the similarities and differences between ISP and sleep paralysis in narcolepsy.

We propose an objective segmentation method for magnetic resonance (MR) images of the brain using self-mapping characteristics of one-dimensional self-organizing maps (SOM). The proposed method requires no operators to specify the representative points, but can segment tissues (such as cerebrospinal fluid, gray matter and white matter) necessary for brain atrophy diagnosis. Doing clinical image experiments, we demonstrate the effectiveness of our method. As a result, we can obtain segmentation results that agree with anatomical structures such as continuities and boundaries of brain tissues. In addition, we propose a computer-aided diagnosis (CAD) system for brain-dock examinations based on the use case analysis of diagnostic reading, and construct a prototype system for reducing loads to diagnosticians that occur in quantitative analyses of the extent of brain atrophy. Through field tests of 193 examples of brain dock medical examinees at Akita Kumiai General Hospital, we also present the prospect of efficient support of diagnostic reading in the clinical field because the aging situation of brain atrophy is readily quantifiable irrespective of a diagnostician's expertise.

Study Objectives: To further investigate mechanisms of isolated sleep paralysis (ISP) in normal individuals, we experimentally elicited ISPs by facilitating sleep onset REM periods (SOREMP), a prerequisite of ISPs, and examined behavioral and psychological measurements relating to ISP appearances. Design: The multi-phasic sleep/wake schedule (MPS) began at approximately midnight and ended when net sleep reached 7.5 hours. Participants were awakened after every 5 min of REM sleep to obtain a maximum number of SOREMPs. Upon each awakening, mentation reports and subjective measurements were collected. Performance tests were then assigned. Setting: Sleep lab, Tokyo Metropolitan Institute for Neurosciences, Japan. Participants: Thirteen healthy Japanese students (10 males) with high self-reported frequencies of ISPs but no other narcolepsy-related symptoms. Measurements and results: From 184 sleep interruptions, 8 ISP episodes were obtained. In within participant comparisons between episodes with and without ISPs, the vigilance task (VT) reaction times were elevated before SOREMPs with ISPs. In between analyses (ISP vs non-ISP), the ISP group showed poorer performance, more complaints of physical, mental, and neurotic symptoms, increased subjective fatigue and increased stage 1 throughout the entire schedule. VT hit rates remained constant in the non-ISP group, but dropped in the later part of schedule in the ISP group. Subjective sleepiness dropped over time in the non-ISP group while it slightly increased in the ISP group. Conclusions: ISP is likely to appear as a phenotype of REM dissociation during SOREMP when participants with low tolerance for disrupted sleepwake rhythms are placed in this type of schedule.

Objective : REM latency is usually 60–120 min, but under certain conditions, its latency may be less than 25 min, in which it is known as sleep onset REM period (SOREMP). In order to identify the factors responsible for the appearance of SOREMP, we used the nocturnal sleep interruption method to investigate whether REM propensity in normal nocturnal sleep, (i.e. circadian variations in REM sleep related to body temperature rhythm), could affect the rate of SOREMP appearance (SOREMP%). Materials and methods : After two adaptation and one baseline nights, we interrupted the nocturnal sleep, either in the second or the fourth cycle (early and late conditions, respectively) of 16 subjects and compared SOREMP% at the second sleep onset between these conditions by χ 2 test. Rectal temperature was measured. Results : SOREMP% was found to be 58.1% in the early condition and 87.5% in the late condition – a significant difference. Body temperature dropped at the second sleep onset in both conditions but the drops did not differ significantly. Conclusion : We concluded that SOREMP% was affected by circadian variations in REM propensity but SOREMP% and body temperature drop did not show a linear relationship. Further studies to discriminate the influence of circadian rhythm factors and slow wave sleep on SOREMP% are called for.

A questionnaire concerning their sleep-related lifestyle and mental health was mailed to people aged in their twenties to fifties living in the Fukushima (North East), Tokyo (Central, Metropolitan) and Okayama (West) areas of Japan. We classified the sleeping pattern of 3642 people (1702 men, 1940 women; mean age 41.3+/-10.67) by multivariational analyses (factor analysis and cluster analysis). They were classified into six groups and defined as 'poor sleeper group' (30.0%), 'good sleeper group' (28.3%), 'long sleeper group' (8.2%), 'short sleeper group' (18.5%), 'irregular sleeper group' (11.3%), and 'Delayed Sleep Phase Syndrome group' (3.7%) based on their characteristics of the factor pattern.

We investigated the relationship between a subject's self-rated lifestyle and their pattern of nocturnal rectal temperature. Fifty-five students participated in the study. Among several significant findings, irregularity and eveningness component of lifestyle (irregular and delayed sleep phase) showed a significant negative correlation with temperature at the morning rising time. Examination of the nocturnal temperature pattern revealed that rectal temperature stayed at its lowest level in the early morning hours in the subjects with irregular and eveningness-like lifestyles.

Fluid-attenuated inversion-recovery (FLAIR) sequences have been reported to provide high sensitivity to a wide range of central nervous system diseases. To our knowledge, however, FLAIR sequences have not been used to study patients with acute cerebral infarcts. We evaluated the usefulness of FLAIR sequences in this context. FLAIR sequences were acquired on a 0.5 T superconducting unit within 8 h of the onset in 19 patients (aged 26-80 years) with a total of 23 ischaemic lesions. The images were reviewed retrospectively by three neuroradiologists, and the FLAIR images were compared with T2-weighted fast spin-echo images. All but one of the ischaemic lesions involving grey matter was clearly demonstrated on FLAIR images as increased signal intensity in cortical or central grey matter. FLAIR images were particularly useful for detecting the hyperacute cortical infarcts within 3 h of onset, which were not readily detected on the spin-echo images. In 9 of 11 patients with complete proximal occlusion, the distal portion of the cerebral artery was visible as an area of high signal intensity on FLAIR images.

To evaluate fluid-attenuated inversion-recovery (FLAIR) magnetic resonance (MR) imaging in the detection of subacute and chronic subarachnoid hemorrhage.The authors performed 19 FLAIR MR imaging examinations at 0.5 T in 14 adult patients with subarachnoid hemorrhage 3-45 days after the ictus and 22 FLAIR examinations in 22 adult control subjects. The detection of subacute and chronic subarachnoid hemorrhage on FLAIR images was compared with the detection on conventional spin-echo MR and computed tomographic (CT) images.In the detection of subacute subarachnoid hemorrhage, FLAIR (100% detection) was significantly superior to T1-weighted imaging (36% detection, P.01), T2-weighted imaging (0% detection, P.02), and CT (45% detection, P.02 [Fisher exact test]). Although FLAIR imaging (63% detection) was superior in chronic subarachnoid hemorrhage detection, there were no statistically significant differences between modalities. FLAIR imaging demonstrated all subarachnoid hemorrhage areas as high-signal-intensity areas within 18 days and up to a maximum of 45 days after the ictus. In a blind comparison, no FLAIR images acquired in control subjects were confused with those acquired in patients.FLAIR diagnostic images are superior to conventional MR or CT images in patients with subacute subarachnoid hemorrhage.

To elucidate the mechanism of large neutral amino acid (LNAA) transport in cerebral gliomas and to evaluate the clinical usefulness of positron emission tomography (PET) with fluorine-18 fluorophenylalanine (18F-Phe), we examined 18 patients with cerebral glioma using dynamic PET and 18F-Phe. By employing two-compartment model analysis, the influx rate K1, the efflux rate k2 and the distribution volume (Vd) of 18F-Phe were estimated in tumour tissue and contralateral normal grey matter. 18F-Phe showed increased accumulation in tumour tissue regardless of the grade of malignancy in all patients. The rate of uptake of 18F-Phe in high-grade glioma was significantly higher than in low-grade glioma (P0.05). However, it was difficult to evaluate the tumour grade only from the 18F-Phe accumulation in individual cases. Values of K1 and Vd were significantly increased in the tumour tissue. The K1 value of the tumour tissue tended to decrease with increasing LNAA concentration in plasma. Therefore, influx of 18F-Phe into tumour tissue is mainly related to the carrier-mediated active transport. It is concluded that PET with 18F-Phe is of clinical value for tumour detection rather than assessment of tumour malignancy.

Cerebral blood flow (CBF), oxygen metabolism (CMRO2), and glucose metabolism (CMRGlc) were measured using positron emission tomography in five patients diagnosed as having mitochondrial encephalomyopathy. The molar ratio between the oxygen and glucose consumptions was reduced diffusely, as CMRO2 was markedly decreased and CMRGlc was slightly reduced. The CBF showed less changes. The CBF increase on hypercapnia was smaller than normal, though this was not significant. CBF with hypocapnia demonstrated a significant reduction compared with the normal. These results suggest that oxidative metabolism is impaired and anaerobic glycolysis relatively stimulated, due to a primary defect of mitochondrial function, and that mild lactic acidosis occurs in brain tissue because of impaired utilisation of pyruvate in the TCA cycle. As these findings appear to indicate directly a characteristic of this disease, such measurements may be a useful tool for assessment of the pathophysiology and for diagnosis of mitochondrial encephalomyopathy.

The purpose of our study was to compare the value of MR imaging with CT in the diagnosis of subarachnoid hemorrhage in the subacute and chronic stages (3 days after the hemorrhagic episode).We performed 42 MR examinations using a 0.5-T unit in 37 patients with subarachnoid hemorrhage caused by a ruptured aneurysm. Examinations were done 4-75 days after the ictus. We obtained 40 T1-weighted, 11 proton density-weighted, 15 T2-weighted, and 28 moderately T2-weighted images. CT was also performed in all patients within 24 hr of the MR examination. Confirmation of the presence of subarachnoid hemorrhage at the time of the MR examination was made by CSF examination using lumbar puncture or surgical findings.In the subacute and chronic stages, subarachnoid hemorrhage was seen as an area of high signal intensity on T1-weighted, proton density-weighted, T2-weighted, and moderately T2-weighted MR images in 63%, 90%, 25%, and 92% of cases, respectively. On CT scans, subarachnoid hemorrhage was seen as an area of high attenuation in only 46% of cases. Especially in the chronic stage, subarachnoid hemorrhage was seen as an area of high signal intensity more frequently by MR imaging than by CT (90% on T1-weighted images; 100% on proton density-weighted images; 25% on T2-weighted images; 100% on moderately T2-weighted images; and 10% on CT scans). High-signal-intensity subarachnoid hemorrhage was demonstrated by MR imaging until a maximum of 39 days after the ictus, whereas high-attenuation subarachnoid hemorrhage was demonstrated by CT until a maximum of 17 days after the ictus.Our findings show that MR imaging is superior to CT for the diagnosis of subacute and chronic subarachnoid hemorrhage. MR imaging is especially useful for the diagnosis of chronic subarachnoid hemorrhage.

To evaluate the usefulness of fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging sequences in the detection of acute subarachnoid hemorrhage (SAH).MR imaging with FLAIR sequences was performed with a 0.5-T superconducting unit in 20 patients (aged 30-72 years) with acute SAH due to a ruptured aneurysm and in 27 control subjects (aged 32-72 years). FLAIR images were obtained 2 hours to 2 days after ictus. Findings were evaluated and compared with computed tomographic (CT) findings.In all patients, acute SAH was clearly demonstrated as an area with signal intensity that was high relative to that of the normal cerebrospinal fluid and surrounding brain parenchyma at FLAIR imaging. This sequence was especially useful in demonstration of acute SAH in the posterior fossa, which was difficult to show at CT because of beam-hardening artifacts. In a double-blind comparison, no FLAIR images acquired in control subjects were confused with those acquired in control subjects were confused with those acquired in patients.FLAIR sequences reliably provide diagnostic images in patients with acute SAH.

Three patients with subacute ischemic cerebral infarction examined by SPECT with 99mTc-ECD and PET within the same day showed signs of luxury perfusion in the subacute phase, which is between 9 to 20 days after the onset. A 99mTc-HMPAO SPECT study was also performed within 2 days of the ECD-SPECT study. ECD-SPECT images of three patients displayed a focal decreased uptake in the infarcted lesions, while in infarcted foci, there was almost equivalent or increased CBF compared to normal and unaffected areas, decreased CMRO2, and high HMPAO uptake. The ECD-SPECT results were similar to those of CMRO2 rather than CBF, though the HMPAO-SPECT image was similar to that of CBF. In one patient, HMPAO images revealed hyperfixation of the tracer. In the chronic phase and in the acute phase before 5 days after the onset, there were no discrepancies among the ECD-SPECT, CBF, HMPAO-SPECT, and CMRO2 images. These observations indicated that 99mTc-ECD is a good indicator of damaged brain tissues in subacute ischemic infarction. They also suggested that 99mTc-ECD is a potential agent with which to evaluate cerebral tissue viability in some pathological states of cerebrovascular disease. The characteristics may be suitable for confirming the effects of thrombolytic therapy in acute ischemia, because these conditions often show signs of luxury perfusion when the therapy is successful.

By means of a high resolution PET scanner, the regional cerebral blood flow (rCBF), cerebral blood volume (rCBV), oxygen extraction fraction (rOEF), and metabolic rate of oxygen (rCMRO2) for major cerebral gyri and deep brain structures were studied in eleven normal volunteers during an eye-covered and ear-unplugged resting condition. Regional CBF was measured by the auto-radiographic method after intravenous administration of H2 15O. Regional OEF and rCMRO2 were measured by the single inhalation of15O2. With MR T1-weighted images as an anatomical reference, thirteen major cerebral gyri, caudate nucleus, lentiform nucleus, thalamus, midbrain, pons, cerebellum and vermis were defined on the CMRO2 images. Values were read by using circular regions of interest 16 mm in diameter. The posterior part of the cingulate gyri had the highest rCBF and rCMRO2 values among brain structures, followed by the lentiform nucleus, the cerebellum, the caudate nucleus, and the thalamus. Parahippocampal gyri had the lowest rCBF and rCMRO2 values amongthe cortical gyri.RegionalOEFforthepontinenuclei (0.34 ± 0.04), the midbrain (0.35 ± 0.05), the parahippocampal gyri (0.35 ± 0.04 for the right and 0.37 ± 0.05 for the left), and the thalami (0.37 ± 0.05 for the right and 0.36 ± 0.04 for the left) were significantly lower than the mean OEF for the cerebral cortices (0.42 ± 0.04) (p < 0.05 or less). The global CBF and CMRO2 were consistent with those obtained by the Kety-Schmidt method. Although several limitations to the quantification derived from an inadequate spacial resolution remain unsolved, the performance of the present PET scanner and the method for the quantification employed provide regional estimates of brain circulation and oxygen metabolism more acurately than the PET system and the steady state method previously used.

A method has been developed to quantitate regional cerebral blood blow (rCBF) using iodine-123-labelled N-isopropyl-p-iodoamphetamine (IMP). This technique requires only two single-photon emission tomography (SPET) scans and one blood sample. Based on a two-compartment model, radioactivity concentrations in the brain for each scan time (early: t e ; delayed: td) aredescribed as: % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa% aaleaacaWG0baabeaakmaabmaabaGaamiDamaaBaaaleaacaWGLbaa% beaaaOGaayjkaiaawMcaaiabg2da9iaadAgacqWIpM+zcaWGdbWaaS% baaSqaaiaadggaaeqaaOWaaeWaaeaacaWG0bWaaSbaaSqaaiaadwga% aeqaaaGccaGLOaGaayzkaaGaey4LIqSaamyzamaalaaabaGaamOzaa% qaaiaadAfadaWgaaWcbaGaamizaaqabaaaaOGaamiDamaaBaaaleaa% caWGLbaabeaaaaa!4D64!\[C_t \left( {t_e } \right) = fC_a \left( {t_e } \right) \otimes e\frac{f}{{V_d }}t_e \] and % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaam4qamaaBa% aaleaacaWG0baabeaakmaabmaabaGaamiDamaaBaaaleaacaWGKbaa% beaaaOGaayjkaiaawMcaaiabg2da9iaadAgacqWIpM+zcaWGdbWaaS% baaSqaaiaadggaaeqaaOWaaeWaaeaacaWG0bWaaSbaaSqaaiaadsga% aeqaaaGccaGLOaGaayzkaaGaey4LIqSaamyzamaalaaabaGaamOzaa% qaaiaadAfadaWgaaWcbaGaamizaaqabaaaaOGaamiDamaaBaaaleaa% caWGKbaabeaaaaa!4D61!\[C_t \left( {t_d } \right) = fC_a \left( {t_d } \right) \otimes e\frac{f}{{V_d }}t_d \] respectively, where ⊗ denotes the convolution integral; C a (t), the arterial input function; f rCBF; and V d , the regional distribution volume of IMP. Calculation of the ratio of the above two equations and a “table look-up” procedure yield a unique pair of rCBF and V d for each region of interest (ROI). A standard input function has been generated by combining the input functions from 12 independent studies prior to this work to avoid frequent arterial blood sampling, and one blood sample is taken at 10 min following IMP administration for calibration of the standard arterial input function. This calibration time was determined such that the integration of the first 40 min of the calibrated, combined input function agreed best with those from 12 individual input functions (the difference was 5.3% on average). This method was applied to eight subjects (two normals and six patients with cerebral infarction), and yielded rCBF values which agreed well with those obtained by a positron emission tomography H2 15O autoradiography method. This method was also found to provide rCBF values that were consistent with those obtained by the non-linear least squares fitting technique and those obtained by conventional microsphere model analysis. The optimum SPET scan times were found to be 40 and 180 min for the early and delayed scans, respectively. These scan times allow the use of a conventional rotating gamma camera for clinical purposes. V d values ranged between 10 and 40 ml/g depending on the pathological condition, thereby suggesting the importance of measuring V d for each ROI. In conclusion, optimization of the blood sampling time and the scanning time enabled quantitative measurement of rCBF with two SPET scans and one blood sample.

Using magnetic resonance imaging, we reviewed 141 infratentorial infarcts in 81 consecutive cases: 65 infarcts were seen in the paramedian pons, while 18 in the posterior inferior cerebellar artery (PICA) territory and 17 in the watershed area between PICA and superior cerebellar artery. No comparable sign or symptom was observed for 44 (31.2%) infarcts, whereas 66 (46.8%) infarcts appeared symptomatic and 31 (22.0%) infarcts were regarded as equivocal mainly due to the coexisting supratentorial lesions or non-localizing symptoms. The frequent coexistence of basal ganglionic small infarcts in those with infratentorial small (15 mm) infarcts implicated their common pathogenetic background. The fact that atrial fibrillation was seen in 33.3% of those with large (15 mm) infarcts whereas it was seen in only 6.5% of those with small infarcts may suggest a cardiogenic embolism as a possible cause of infratentorial large infarcts. Major artery occlusive lesion was seen in 15 of 22 cases with cerebellar infarction, whereas no occlusive lesion was seen in the majority of cases with pontine small infarcts. With MR imaging, infratentorial infarcts were detected more frequently than in the previous studies based on X-ray CT, and they can be considered as a benign condition.

We interrupted the nocturnal sleep of human subjects for an hour and investigated the effect on body temperature (BT). The interruption elicited sleep onset rapid eye movement period (SOREMP). We compared the BT patterns obtained during nights with SOREMP at the second sleep onset (SOREMP nights) and those obtained during nights without SOREMPs (non-SOREMP nights) with those obtained during baseline nights. BT decreased markedly after sleep interruption on both SOREMP and non-SOREMP nights. It remained lower for 2 hours after the second sleep onset when compared with the corresponding period on the baseline nights. Consequently, the minimum BT was lower and the timing of the minimum was advanced when compared with baseline. The fall of BT after sleep interruption was not accompanied by any increase in slow wave sleep (SWS, stage 3 + 4) when compared with the baseline nights. Thus, we suggest that no direct relationship exists between the decrease of BT and the amount of SWS. On SOREMP nights, the fall of BT from lights-out to the second sleep onset was larger than on non-SOREMP nights. This lower body temperature at the second sleep onset may reflect the physiological background necessary for the appearance of SOREMPs.

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.

A rare case of multiple medullary venous malformations in the right cerebral hemisphere is reported. The literature review yielded only one case of multiple medullary venous malformations. Computed tomography scan showed multiple calcified lesions with linear contrast enhancement representing abnormal dilated vessels and mild atrophic change of the right cerebral hemisphere. Single-photon emission computed tomography using N-isopropyl-p-(123I) iodoamphetamine demonstrated decreased cerebral blood flow in the right cerebral hemisphere.

We have studied eight patients with thalamic tumours using positron emission tomography (PET) with 15O-labelled gas and 18F-fluorodeoxyglucose and/or 11C-methionine. PET with 11C-methionine delineated clearly the extension of tumour and provided information for selection of appropriate treatment and evaluation of therapeutic effects on the tumour. PET with 18F-fluorodeoxyglucose displayed malignant tumour as hypermetabolic foci and was useful for deciding the target of stereotactic needle biopsy. Concerning neurological function, hypoperfusion and hypometabolism were observed in the ipsilateral cortex. These results can be interpreted as remote effects via thalamocortical connections.

A cervical cord tumor was examined with positron emission tomography using L-methyl-({sup 11}C)methionine. The radioactive tracer accumulated in the solid parts (but not in the associated cysts) of the neoplasm, which at histology was found to be an ependymoma.

We present a rare case of medullary venous malformations with an arterial component coexisting with two small arteriovenous malformations in the same area. The onset was abrupt with subcortical hematoma due to the rupture of one arteriovenous malformation in the frontal area. Single photon emission computed tomography using 99mTc-hexamethylpropyleneamine oxime showed a high-uptake area around the hematoma suggesting increased blood flow. Two types of vascular malformation coexisting in the same area support a theory of congenital malformation originating in intrauterine life.

A differentiation between embolic versus thrombotic infarction has been attempted on the basis of sequential CT of 32 patients fulfilling our clinical and angiographic criteria for embolic or thrombotic cerebral infarction of the middle cerebral arterial distribution. In the 20 patients of the embolic group, a large homogeneous low attenuation area was seen in every case. In 18 of these 20 patients, the low attenuation area extended from the deep brain to the cortex. In the 12 patients of the thrombotic group, 10 had an inhomogeneous low attenuation area that did not involve the cortices in 8 cases. The frequency of hemorrhagic transformation in the embolic group was higher than in the thrombotic group. Computed tomography showed discrete areas of increased attenuation corresponding to an angiographically occluded artery in 7 of the 20 patients in the embolic group. Sequential CT can assist in differentiating between embolic and thrombotic infarction.

We report an anterior cranial fossa dural arteriovenous fistula with a varix mimicking an aneurysm on CT and MRI.

To investigate changes in cerebral circulation and oxygen metabolism during aging, regional cerebral blood flow (rCBF), regional oxygen extraction fraction (rOEF), regional cerebral metabolic rate of oxygen (rCMRO2) and regional cerebral blood volume (rCBV) were measured using the 15O labelled gas inhalation technique and a multi-slice positron emission tomograph (PET) in 22 healthy volunteers, aged from 26 to 64 years old. The measurements were performed with subjects at rest, without sensory deprivation. The values of rCBF, rOEF, rCMRO2 and rCBV in more than 40 anatomical structures of the brain were evaluated by studying a large series of scans in each region of interest after the functional PET image had been anatomically identified using x-ray computed tomographic images corresponding to the PET. In mean gray values, only CMRO2 showed significant reduction with age. rCMRO2 significantly decreased with age only in the supratentrium, and much more in the left hemisphere. Especially remarkable was rCMRO2 reduction in the left caudate region. Both CBF and OEF were variable and less age-dependent. It was concluded that CMRO2 could be reflecting healthy brain aging most properly.

This article is a survey study, followed by an experimental study, examining the differences of sleep-wake habits and sleep electroencephalographic (EEG) variables between morning and evening type subjects (Ss). In the survey study, the Japanese version of the Horne and Ostberg Morningness-Eveningness Questionnaire and Life Habits Inventory (LHI) were administered to approximately 1,500 university students. The survey results showed that the two types were significantly different from each other in terms of retiring and arising time, sleep latency, mood on arising, nap, adequate amount of sleep, number of times of staying awake all night, and variability in bedtime, arising time, and sleep length. These results suggested that evening type Ss had more irregular and/or flexible sleep-wake habits than morning type Ss. In the experimental study, 10 morning and 11 evening type Ss were selected from the population included in the survey study, and polysomnograms were obtained. The results showed that only in rapid eye movement (REM) latency did morning type Ss significantly differ from evening type Ss. REM latency might be related to personality factors, particularly to neuroticism and anxiety.

放射線治療を行った原発性肺癌症例のうち各々の目的とする放射線治療が完了された症例は641例であり, 今回は手術と放射線照射の併用治療を行った271例について, 肺癌の臓器特殊性である組織型の多様性, 悪性度, 病巣の発生部位および病期などの差により手術との併用治療が予後に対していかなる効果を示すかについて検討を試み, 各病型に対して適正なる併用治療方法を確立し, 今後の肺癌治療成績向± に寄与せんと本研究を行った.

A system for CBF measurement using an H215O autoradiographic method and positron emission tomography (PET) has been designed and installed as a clinical tool. Following an intravenous injection of H215O, a radioactivity accumulation in the brain tissue for 60 s and a continuous record of radioactivity in arterial blood were measured by a high counting speed PET device and a beta-ray detector, respectively, and CBF was calculated by a table-lookup procedure. First, this method was compared with the C15O2 inhalation steady-state method on 17 cerebrovascular disease patients and four normal subjects. The two values for CBF agreed with each other when H215O autoradiographic method was applied by correction for the dispersion in the measured arterial radioactivity–time curve. However, without the correction, the CBF by the H215O autoradiographic method revealed substantial overestimation by 30.6 ± 17.5%. A reduced gray/white ratio of CBF was also observed in the H215O autoradiographic method. Second, simulation was performed in order to determine optimal accumulation time by PET scan; the result was that errors due to dispersion and time mismatch became critical as the accumulation time was shortened to

Forty-four normal male students, aged 18-23 years were studied. After adaptation and baseline night (BN), 3 or 4 consecutive nights were interrupted by a forced awakening (10-90 min) once a night (ENs). Subjects (Ss) were awakened after they had slept for the first sleep cycle plus 20 min of NREM sleep in the 2nd cycle. The REM latencies following return to sleep showed a bimodal distribution separated by 25-30 min. The ENs were divided into 2 clusters: SOREMP (sleep onset REM period) and non-SOREMP nights. After interruption, the 2nd and the 3rd REM durations increased on non-SOREMP nights compared to SOREMP nights. We plotted, separately for SOREMP and non-SOREMP nights, the fluctuation of REM episode probability (FRP) at successive points in time. We examined the correspondence of FRPs derived from the sleep-independent, the sleep-dependent, and the reset hypotheses, with FRP of intact BN. On both SOREMP and non-SOREMP nights, none of the 3 models corresponded with BN. Thus, we suggest that, for both SOREMP and non-SOREMP nights, intervening wakefulness cancels the pre-awakening REM rhythm, and a new REM rhythm starts with or without SOREMP. We discuss factors influencing the rate of SOREMP occurrence (SOREMP %), such as circadian effect, individual differences, length of interruption, and pre-awakening NREM duration.

We have developed a method that allows us to place regions of interest on X-ray CT (XCT) images that are automatically adjusted to positron emission tomography (PET) images from the same patient. A face mask with landmarks was used during PET and XCT studies for matching slice positions between PET and XCT. Anatomical locations in different images of the same slice can be accurately adjusted using the landmarks and a video system. In our clinical experience misadjustments of the slice position are on the average less than 2 mm in axial distance and 1.0 degrees in slice angle. The method is easily applicable to any PET or XCT device.

犬の咬傷による右総頸動脈閉塞症から脳梗塞を起こした一例を報告した.本例は, 受傷直後より意識障害, 構音障害, 左片麻痺, 左半身知覚鈍麻, 病態失認, 左半側空間失認などの右大脳半球症状を呈した.受傷数時間後のDSAで右総頸動脈の完全閉塞が認められ, 頸部CTでは右総頸動脈の造影欠損を認めた.頭部CTで, 右中大脳動脈領域と右視床に低吸収域が認められた.本例における総頸動脈閉塞機序として, 外傷性解離性動脈瘤, あるいは外傷に基づく血管壁内血腫による急激な血管閉塞の可能性が考えられた.また, 本例で施行された動脈性DSAは, 病変部に対する直接的侵襲を軽減し得る点, また造影剤を節約できるなどの点で有用な検査である.

The effects of radiochemotherapy on blood flow, blood volume, and consumption of oxygen and glucose in tumor tissue and normal brain were studied by positron emission tomography. Thirteen patients with cerebral gliomas were included, and they were examined before, during, and within approximately 1 month after the therapy. The 15O-labeled gas steady state inhalation and the 18F-fluorodeoxyglucose methods were used. After the therapy, glucose consumption and blood volume decreased (p less than 0.03) in the tumoral tissue. In the structurally (CT) normal gray matter, blood flow, blood volume, and oxygen consumption did not show any significant changes; oxygen extraction fraction, glucose consumption, and glucose extraction fraction, however, decreased significantly (p less than 0.05, less than 0.02, and less than 0.03, respectively).

Comparison of Doppler flow parameters measured by pulsed Doppler method with angiographic findings was studied in 77 patients (121 common carotid arteries) . A RT-3600 scanner which employs a 5-MHz transducer in the Doppler mode, was used for the duplex studies. Duplex studies were performed after cerebral angiography. All patients had images of right and/or left common carotid artery obtained by digital subtraction angiography, and conventional cerebral angiography. The severity of atheroscler-osis was scored by angiographic findings : atheromatous plaque, wall irregularity, stenosis, tortousity, and so on. Systolic velocity, diastolic velocity, mean velocity, and pulsatility index were measured by the pulsed Doppler technique in the common carotid artery. The systolic velocity, diastolic velocity, and mean velocity showed negative currelations with the atherosclerotic score on angiograms, and the pulsatility index showed positive correlation with that on angiograms. Pulsatility index in patients with cerebral infarction in the examind internal carotid artery distribution was statistically significantly higher than that in patients having no ischemic lesions. It was thought that Doppler flow parameters, such as systolic velocity, diastolic velocity, mean velocity, and pulsatility index reflected well the severity of atherosclerosis, and Doppler ultrasound was a useful method for evaluating atherosclerosis and cerebral ischemic lesions.

In four patients highly suspected of having delayed radiation necrosis of the brain, regional cerebral blood flow and metabolism were studied by using positron emission tomography (PET) with the 15O-labelled gases, 18F-fluorodeoxyglucose (18FDG). All four patients showed marked decreases in glucose and oxygen consumption in the lesion with that suspected pathology in comparison with those in normal brain parenchyma. Two of them were histologically proved to have radiation injuries (one was radiation necrosis and another was early delayed reactions). But one patient was histologically proved to have a recurrent tumor. Although metabolic study with PET using 18FDG is generally an excellent procedure for differentiation between radiation injuries and recurrent brain tumor, these results imply that in some cases the differential diagnosis is difficult even with 18FDG. The present study demonstrated considerably more pronounced reduction in the metabolism than the decrease of the blood flow in the lesion with radiation necrosis. This result would indicate that the primary effect causing the radiation necrosis is a direct effect of irradiation on neural tissue rather than the capillary damage.

Early computed tomographic (CT) findings (scans obtained within 6 hours of the onset of stroke) were retrospectively analyzed in 25 patients with embolic cerebral infarction of the middle cerebral artery or internal carotid artery distribution, including the lentiform nucleus, diagnosed on the basis of findings at sequential CT. CT scans were analyzed for the following: (a) an obscured outline or partial disappearance of the lentiform nucleus, (b) a slight decrease in tissue density, or (c) effacement of the cortical sulci. One or more of these findings was recognized in 23 of 25 patients (92%). The first finding was noted most frequently, and it appeared earliest. Obscuration of the lentiform nucleus was thought to be an important early sign of cerebral infarction, including the lentiform nucleus.

The oxygen extraction fraction (OEF) at maximally vasodilated tissue in patients with chronic cerebrovascular disease was evaluated using positron emission tomography. The vascular responsiveness to changes in PaCO2 was measured by the H215O autoradiographic method. It was correlated with the resting-state OEF, as estimated using the 15O steady-state method. The subjects comprised 15 patients with unilateral or bilateral occlusion and stenosis of the internal carotid artery or middle cerebral artery or moyamoya disease. In hypercapnia, the scattergram between the OEF and the vascular responsiveness to changes in PaCO2 revealed a significant negative correlation in 11 of 19 studies on these patients, and the OEF at the zero cross point of the regression line with a vascular responsiveness of 0 was 0.53 ± 0.08 (n = 11). This OEF in the resting state corresponds to exhaustion of the capacity for vasodilation. The vasodilatory capacity is discussed in relation to the lower limit of autoregulation.