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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.

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.

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%).

Cerebral blood flow (CBF), oxygen metabolism (CMRO2), and glucose metabolism (CMRGlc) were measure 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 imparied 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.

We studied 15 patients clinically suspected to have recurrent brain tumor or radiation injury, using positron emission tomography (PET) with 18F-fluorodeoxyglucose (18FDG) and L-methyl-11C-methionine (11C-Met). PET with 11C-Met (Met-PET) clearly delineated the extent of recurrent brain tumor as focal areas of increased accumulation of 11C-Met, and was useful for early detection of recurrent brain tumor. PET with 18FDG (FDG-PET) showed focal 18FDG-hypermetabolism in one patient with malignant transformation of low grade glioma, and demonstrated its usefulness for evaluation of malignant transformation. 18FDG-hypometabolism was observed in all patients with radiation injury, but was also found in one patient with recurrent malignant brain tumor. 11C-Met uptake in 3 patients with radiation injury was similar to that of the normal cortical tissue. FDG-PET can be used to initially exclude recurrent brain tumor which is seen as 18FDG-hypermetabolism. The combined use of Met-PET in addition to FDG-PET can improve the accuracy of differentiation of recurrent brain tumor with 18FDG-hypometabolism from radiation injury.

The present study investigated some differences between ‘morning’ and ‘evening’ types in life habits, particularly concerning meals, ingestion of caffeine and alcohol, and smoking. The Life Habits Inventory and the Japanese version of Home and Östberg Morningness-Eveningness Questionnaire were administered to approximately 1500 students, and data on life habits of the morning types were compared with those of the evening types. Significant differences between these types were found in frequency of night meals, smoking, and ingestion of caffeine and alcohol. Although significant differences were not found for mealtimes, 34.8% of the evening types typically did not eat breakfast. These differences were discussed from viewpoint of chronopharmacology and personality.

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 singlephoton emissioncomputed tomography, and the other is persistent asymmetry with alternation in Paco2using 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.

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.

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 aras 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.

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: te; 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; Ca(t), the arterial input function; f rCBF; and Vd, 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 Vd 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 H215O 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. Vd values ranged between 10 and 40 ml/g depending on the pathological condition, thereby suggesting the importance of measuring Vd 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.

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−1min−1in 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.

We studied 15 patients clinically suspected to have recurrent brain tumor or radiation injury, using positron emission tomography (PET) with 18F-fluorodeoxyglucose (18FDG) and L-methyl-11C-methionine (11C-Met). PET with 11C-Met (Met-PET) clearly delineated the extent of recurrent brain tumor as focal areas of increased accumulation of 11C-Met, and was useful for early detection of recurrent brain tumor. PET with 18FDG (FDG-PET) showed focal 18FDG-hypermetabolism in one patient with malignant transformation of low grade glioma, and demonstrated its usefulness for evaluation of malignant transformation. 18FDG-hypometabolism was observed in all patients with radiation injury, but was also found in one patient with recurrent malignant brain tumor. 11C-Met uptake in 3 patients with radiation injury was similar to that of the normal cortical tissue. FDG-PET can be used to initially exclude recurrent brain tumor which is seen as 18FDG-hypermetabolism. The combined use of Met-PET in addition to FDG-PET can improve the accuracy of differentiation of recurrent brain tumor with 18FDG-hypometabolism from radiation injury.

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.

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 <2 mm in axial distance and 1.0° in slice angle. The method is easily applicable to any PET or XCT device.

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 ∼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 < 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 < 0.05, < 0.02, and < 0.03, respectively).

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 C15O2inhalation 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 <60 s.

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 and18F-Phe. By employing two-compartment model analysis, the influx rateK1, the efflux ratek2 and the distribution volume (Vd) of18F-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 of18F-Phe in high-grade glioma was significantly higher than in low-grade glioma (P <0.05). However, it was difficult to evaluate the tumour grade only from the18F-Phe accumulation in individual cases. Values ofK1 andVd were significantly increased in the tumour tissue. TheK1 value of the tumour tissue tended to decrease with increasing LNAA concentration in plasma. Therefore, influx of18F-Phe into tumour tissue is mainly related to the carrier-mediated active transport. It is concluded that PET with18F-Phe is of clinical value for tumour detection rather than assessment of tumour malignancy.

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 PaCO2was 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 PaCO2revealed 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.

The radioisotope distribution following intravenous injection of 99mTc-labeled hexamethylpropyleneamine oxime (HM-PAO) in the brain was measured by single photon emission computed tomography (SPECT) and corrected for the nonlinearity caused by differences in net extraction. The “linearization” correction was based on a three compartment model, and it required a region of reference to normalize the SPECT image in terms of regional cerebral blood flow distribution. Two different regions of reference, the cerebellum and the whole brain, were tested. The uncorrected and corrected HM-PAO images were compared with cerebral blood flow (CBF) image measured by the C15O2inhalation steady state method and positron emission tomography (PET). The relationship between uncorrected HM-PAO and PET–CBF showed a correlation coefficient of 0.85 but tended to saturate at high CBF values, whereas it was improved to 0.93 after the “linearization” correction. The whole-brain normalization worked just as well as normalization using the cerebellum. This study constitutes a validation of the “linearization” correction and it suggests that after linearization the HM-PAO image may be scaled to absolute CBF by employing a global hemispheric CBF value as measured by the nontomographic 133Xe clearance method.

Abstract: 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.

Abstract: We have encountered a ruptured aneurysm as a filling defect in cisternal blood on CT in patients with acute subarachnoid haemorrhage (SAH), as high-attenuation blood can act as a contrast medium. We term this finding the “filling defect sign”. To evaluate the usefulness of the sign in the diagnosis of a ruptured aneurysm, we retrospectively analysed CT with 10-mm-thick slices obtained within 2 days of onset of SAH in 100 consecutive patients. The sign was observed in 30 of the 100 patients, and in 13 (68 %) of 19 patients with a ruptured aneurysm more than 10 mm in diameter. The filling defect sign is useful in predicting the site of rupture.

A cervical cord tumor was examined with positron emission tomography using L-methyl-[11C]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 report an anterior cranial fossa dural arteriovenous fistula with a varix mimicking an aneurysm on CT and MRI.