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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.

The present study aimed to evaluate whether the use of a smoothing filter would improve the image quality in pediatric

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.

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). As the proposed method requires the appropriate parameters to segment tissues (such as cerebrospinal fluid, gray matter and white matter) that are necessary for brain atrophy diagnosis, first we derive the optimal parameter set through the preliminary experiments. The main contribution of this work is to evaluate the effectiveness of the proposed method, considering the conventional methods that are highly accurate in terms of usefulness as classification techniques. We focus on Fuzzy C-means (FCM) and Expectation Maximization Gaussian Mixture (EM-GM) with previous setting of the number of clusters, and then Mean Shift (MS) without previous setting of the number of clusters. Through the comparative experiments on the two metrics, we confirmed that our method could achieve higher accuracy than these conventional methods. 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.

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.

The hypothesis that there is a strict relationship between dreams and a specific rapid eye movement (REM) sleep mechanism is controversial. Many researchers have recently denied this relationship, yet none of their studies have simultaneously controlled both sleep length and depth prior to non-REM (NREM) and REM sleep awakenings, due to the natural rigid order of the NREM--REM sleep cycle. The failure to control sleep length and depth prior to arousal has confounded interpretations of the REM-dreams relationship. We have hypothesised that different physiological mechanisms underlie dreaming during REM and NREM sleep, based on recent findings concerning the specificity of REM sleep for cognitive function. Using the Sleep Interruption Technique, we elicited sleep onset REM periods (SOREMP) from 13 normal subjects to collect SOREMP and sleep onset NREM (NREMP) dreams without the confounds described above. Regression analyses showed that SOREMP dream occurrences were significantly related to the amount of REM sleep, while NREMP dream occurrences were related to arousals from NREM sleep. Dream properties evaluated using the Dream Property Scale showed qualitative differences between SOREMP and NREMP dream reports. These results support our hypothesis and we have concluded that although 'dreaming' may occur during both REM and NREM periods as previous researchers have suggested, the dreams obtained from these distinct periods differ significantly in their quantitative and qualitative aspects and are likely to be produced by different mechanisms.

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.

To measure regional cerebral blood flow (rCBF) by blood sampling using 99mTc-ECD we devised a method of measuring the radioactive concentration in arterial blood sample with a gamma camera. In this method the head and a blood sample are placed within the same visual field to record the SPECT data of both specimens simultaneously. The results of an evaluation of the counting rate performance, applying the 30 hours decaying method using 99mTc solution showed that this method is not comparable to the well-type scintillation counter and in clinical cases the active concentration in arterial blood sample remained well within the dynamic range. In addition, examination of the influence of scattered radiation from the brain by the dilution method showed that it was negligible at a distance of more than 7.5 cm between the brain and the arterial blood sample. In the present study we placed a head-shaped phantom next to the sample. The results of the examinations suggested that this method is suitable for clinical application, and because it does not require a well-type scintillation counter, it is expected to find wide application.

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.

PURPOSE: To evaluate the usefulness of three-dimensional CT angiography (CTA), in which contrast material is used to create reformations of dynamic scans, in the diagnosis and the preoperative evaluation of cerebral aneurysms. METHODS: We used 3-D CTA to examine 65 patients with suspected or angiographically verified cerebral aneurysms. A blind study was performed to evaluate the diagnostic accuracy of 3-D CTA for cerebral aneurysms with the use of conventional angiography as the reference standard. RESULTS: In 50 patients, conventional angiography revealed 73 cerebral aneurysms ranging from 2 to 32 mm in maximum diameter. Three of the 73 cerebral aneurysms were located outside the imaging volume of 3-D CTA. The sensitivities of the two neuroradiologists for the remaining 70 aneurysms were 67% and 70%, respectively. Although 3-D CTA depicted cerebral aneurysms 5 mm or larger with good accuracy, it was less useful for the detection of smaller aneurysms. For the evaluation of giant aneurysms, this technique elucidated the relationships among the aneurysm, surrounding arteries, and neighboring bone structure. CONCLUSION: Three-dimensional CTA is useful for the diagnosis of cerebral aneurysms with diameters of 5 mm or more. This technique is especially useful in the preoperative evaluation of giant aneurysms.

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.

PURPOSE: To evaluate the differences between fludeoxyglucose F 18 (FDG) and L-methyl-11C-methionine (11C-methionine) as tracers for positron emission tomography (PET) in the evaluation of brain tumors. METHODS: We analyzed 10 patients with histologically verified cerebral glioma or meningioma and 1 patient with a neuroradiologic diagnosis of low-grade glioma by using FDG, 11C-methionine, and PET. We qualitatively and quantitatively evaluated the extent and degree of accumulation of FDG and 11C-methionine in the tumor tissue. RESULTS: Although PET with FDG depicted malignant tumors as a hot spot in all cases, it was not able to delineate the extent of the tumor. Conversely, PET with 11C-methionine outlined the tumors as areas of increased accumulation of 11C-methionine, regardless of the degree of malignancy. CONCLUSION: PET with FDG and with 11C-methionine can play complementary roles in the evaluation of brain tumors.

We evaluated whether PET with L-methyl-11C-methionine (11C-methionine) was clinically useful in distinguishing neoplastic from non-neoplastic intracerebral hematoma.We examined eight patients with neoplastic (n = 4) or non-neoplastic (n = 4) intracerebral hematomas between 5 and 68 days after the bleeding episode using PET with 11C-methionine (Met-PET).Carbon-11-methionine accumulated in the area surrounding the hematoma in both groups, except in one patient with an acute hypertensive hematoma. Between 22 and 45 days after the ictus, non-neoplastic hematomas showed increased 11C-methionine accumulation largely in accordance with the contrast-enhanced areas on CT or MR images; whereas between 14 and 68 days after bleeding, neoplastic hematomas showed increased 11C-methionine accumulation that extended beyond the contrast-enhanced areas on CT or MR images. The intensity of 11C-methionine accumulation in tumor tissue was greater than that in non-neoplastic hematomas.Preliminary results suggest that Met-PET can distinguish neoplastic from non-neoplastic hematomas on the basis of differences in lesion extent compared with CT or MR findings.

This study evaluates ischemic damage to central benzodiazepine (BZD) receptor binding in the brain with [123]iomazenil SPECT in relation to CT hypodense lesions and blood flow abnormalities.Nine patients with middle cerebral artery territory infarction were studied. Iomazenil images obtained 180 min postinjection were analyzed for BZD receptor binding. The cortical infraction, visualized as CT hypodense area on CT, the peri-infarct area, visualized as normodensity surrounding the infarction on CT, the intrahemispheric remote area and the cerebellum were analyzed by taking the ratio of the lesion to contralateral mirror region (L/C ratio). CT during the chronic stage and perfusion images obtained during the smallest time difference between the two studies were used for comparative analysis.The mean L/C ratio of iomazenil uptake was 0.53 +/_ 0.08, 0.79 +/- 0.07, 0.98 +/- 0.03 and 1.00 +/- 0.04 in the infarct, peri-infarct and remote areas and the cerebellum, respectively. The infarct and peri-infarct areas showed significant decrease compared with unity. The corresponding mean L/C ratio for blood flow was 0.52 +/- 0.08, 0.73 +/- 0.07, 0.83 +/- 0.09, and 0.80 +/- 0.07, respectively. In all areas, the ratios were significantly decreased compared with unity. There was significant difference between the L/C ratio for blood flow and iomazenil in the remote area and the cerebellum.Iodine-123-iomazenil SPECT imaging may provide new information on ischemic damage to the brain, particularly neurons.

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.

Iodine-123-iodoamphetamine (IMP) is commonly used as a flow tracer for SPECT due to its large first-pass extraction fraction. Significant clearance from the brain, however, causes changes in distribution and underestimation of CBF values when a conventional microsphere model is applied to prolonged data acquisition. We have developed a rapid method to calculate CBF images in which clearance effects are taken into account.A dynamic SPECT scan was obtained from five subjects (four patients with cerebral infarctions and one healthy volunteer) following intravenous injection of IMP lasting 1 min. The arterial input function was obtained by frequent blood sampling and measurement of the octanol extraction ratio. The dynamic images were weighted and integrated so that the look-up table procedures yielded values of CBF and distribution volume (Vd) simultaneously.Calculated values for CBF and Vd were consistent with those determined by nonlinear least squares fitting [CBF: Y = 1.03X-0.30 (ml/100 ml/min), r = 0.998, p0.001; Vd: Y = 0.99X-0.11 (ml/ml), r = 0.99, p0.001] and calculated CBF correlated significantly with CBF measured by PET [Y = 0.85X-0.15 (ml/100 ml/min), r = 0.92, p0.001].This technique is valid for estimating CBF.

We serially examined a patient with Creutzfeldt-Jakob disease using fludeoxyglucose F 18 and positron emission tomography. Marked cerebral hypometabolism reflected clinical deterioration in the early stages of Creutzfeldt-Jakob disease when no parenchymal abnormalities were present on MR imaging.

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.

MR in two patients with unusual widening of the Virchow-Robin spaces showed multiple cystic foci up to 2 cm in diameter along the perforating medullary arteries in the cerebral white matter, mainly in one cerebral hemisphere. These areas were of the same signal intensity as cerebrospinal fluid on all pulse sequences. In one patient, the cystic foci in the white matter were biopsied and histologically confirmed to be large Virchow-Robin spaces.

We report preliminary results applying fluid-attenuated inversion-recovery (FLAIR) sequences to three patients with acute subarachnoid hemorrhage. Acute subarachnoid hemorrhage could be clearly demonstrated as areas of high signal intensity on FLAIR sequences in all patients. These preliminary results suggest that with FLAIR sequences one could reliably diagnose acute subarachnoid hemorrhage.

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.

The degree of collateral circulation in patients with unilaterally chronic internal carotid artery occlusion was estimated by mean transit time of contrast material in rapid sequence carotid angiography (Angiographic MTT), and compared with cerebral blood flow and oxygen metabolism measured by PET. In normal density region on X-ray CT, a significant negative correlation was observed between Angiographic MTT and cerebral blood flow (CBF). This indicates that cerebral blood flow can be estimated by Angiographic MTT. It has been reported that the ratio of cerebral blood volume (CBV) to CBF (CBV/CBF), i.e., mean transit time determined by PET well agreed with OEF, and is good indicator for brain circulation reserve. In this study, no significant correlation was observed between Angiographic MTT and CBV/CBF. However, a significant positive correlation was observed between Angiographic MTT and oxygen extraction fraction (OEF), and no significant correlation was observed between Angiographic MTT and oxygen consumption rate (CMRO2). These indicates that Angiographic MTT may be indicator for brain circulation reserve.

Technetium-99m-HMPAO can be used to evaluate abnormal brain perfusion in the hyperacute stage of stroke.We investigated cerebral blood flow using 99mTc-HMPAO SPECT in 31 patients within 6 hr after the onset of cerebral infarction and analyzed the relationship between abnormal perfusion and morphological changes on follow-up CT scans. Patients were classified into an infarct group and a noninfarct group, and the lesions on SPECT images were divided into infarct and peri-infarct regions.Among a total of 30 infarct regions, three lesions studied at 1.5, 2.5 and 5 hr after the ictus showed local hyperperfusion suggestive of early postischemic hyperemia, while the other 27 lesions demonstrated local hypoperfusion. All of the peri-infarct regions showed moderate hypoperfusion. The noninfarct group consisted of five patients, four of whom showed no perfusion abnormalities. The lesion-to-contralateral radioactivity ratios for the infarct and peri-infarct regions were respectively 0.48 +/- 0.14 and 0.75 +/- 0.10 in the patients with hypoperfusion, while the right-to-left ratio in the noninfarct group was 0.97 +/- 0.10.This SPECT study of cerebral blood flow demonstrates that local hyperperfusion occurs in some infarcts even within 6 hr of onset and that infarcted and morphological viable brain can be distinguished by a lesion-to-contralateral radioactivity ratio of 0.6 within this time range.

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.

The regional brain uptake of 99mTc-N,N'-(1,2-ethylenediyl)bis-L-cysteine diethyl ester (99mTc-bicisate) measured by single photon emission computed tomography (SPECT) was compared with the regional CBF and CMRO2 measured by positron emission tomography in patients with cerebrovascular disease. Nine patients with the diagnosis of cerebral ischemic disorders (n = 7) or cerebral hemorrhage (n = 2) were studied. 99mTc-Bicisate brain uptake correlated with CBF and CMRO2. However, 99mTc-bicisate uptake did not reflect CBF in the single lesion showing luxury perfusion, which seemed to resemble a CMRO2 image. Though quantitative analysis showed the nonlinear correspondence of 99mTc-bicisate brain uptake with CBF and CMRO2, this correspondence could be corrected into a more linear relationship using a correction factor. 99mTc-Bicisate washout from the brain had no correlation to CBF and CMRO2. This diffuse decreasing washout rate was approximately 15% during the first hour after injection. By using the lipophilic fraction of arterial blood and a linearized correction of 99mTc-bicisate SPECT images, the feasibility of obtaining a factor-related CBF and CMRO2 was suggested from our data. These results suggested that 99mTc-bicisate had good characteristics for routine clinical use with SPECT to display the brain function in patients with neurological disorders.

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.

IMP is a flow tracer due to a large first pass extraction fraction and high affinity in the brain, but significant clearance from the brain causes change of distribution when the scan start time is delayed. The purpose of the present study is to develop a new method to rapidly calculate a quantitative CBF image by taking into account for the clearance effects. A dynamic SPECT scan was performed on 5 subjects (4 patients with cerebral infarction and 1 normal volunteer) following slow intravenous infusion of 123I-IMP. The arterial input function was obtained by frequent blood sampling and by measuring an octanol extraction ratio for each sample. Firstly, non-linear least square fitting (NLS) was performed to investigate the tracer kinetics of 123I-IMP. The 3 compartment model analysis yielded negligibly small k3 (retaining rate constant) (0.0056 +/- 0.0128 (ml/ml/min)), and consistent k1 (transport rate constant) with those determined by 2 compartment model (2CM) analysis (r = 0.96, p0.001). In addition, k1 was consistent with CBF measured by 15O water PET technique. These observations suggested validity of using 2CM for describing the IMP tracer kinetics. Secondly, a weighted integration (WI) technique has been implemented to calculate rapidly images of CBF and partition coefficient (Vd). The WI technique yielded values of CBF (k1) and Vd (k1/k2). They were confirmed to be consistent with those determined by NLS technique (CBF; r = 0.99, p0.001, Vd; r = 0.99, p0.001), and calculated k1 agreed well with PET CBF (r = 0.91, p0.001). We observed changed Vd in infarcted patients. This supports an importance for calculating of Vd image. Vd image will provide additional clinical information because 123I-IMP binding mechanism may be related to cell viability.

We have developed a new method to quantitate regional cerebral blood flow (CBF) using 123I-IMP and SPECT. This technique requires two SPECT scans and one blood sampling. Based on the 2 compartment model (influx; k1 and outflux; k2), a table between k2 and ratio of 1st scan counts/2nd scan counts was calculated, and a table look up procedure yielded a unique pair of k1 (CBF) and distribution volume (Vd = k1/k2) for each region of interest (ROI). The arterial input function was obtained by one point blood sampling to calibrate the standard input function, which has been obtained from the previous study on 12 subjects. This method was applied to 5 subjects including 1 healthy volunteer and 4 patients with cerebral infarction, and the regional CBF results were compared with those measured by H2(15)O PET technique. Optimized scan time combination was 40, 180 min which provided the best correlation with H2(15)O-CBF. The Vd values obtained in infarcted regions were significantly smaller than those in normal regions, suggesting the importance of measuring Vd for each ROI.