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A 75-year-old woman was referred to our department in October 2022 with ataxia and involuntary movements of the right upper and lower limbs. She had experienced a left pontine hemorrhage in March 2021, which was managed conservatively. However, she had residual right-sided hemiplegia. In addition, she had cerebellar ataxia and a 2 ‍Hz resting tremor of the right upper and lower limbs, which was enhanced while maintaining posture and contemplation. Based on her history, and the findings of MRI and nuclear medicine imaging, we diagnosed the patient with Holmes tremor due to pontine hemorrhage. Holmes tremor is a rare movement disorder secondary to brainstem and thalamic lesions, characterized by a unilateral low-frequency tremor. In this case, 123 I-IMP SPECT and MRI shows damage to the cerebellothalamic tract and dentaro-rubro-olivary pathway.

We report a 74-year-old female patient with Parkinson disease (PD). Around 2010, she developed depression and bradykinesia and was diagnosed as PD. In July 2014, she came to our hospital, of which she lived in the neighborhood. In the last part of December 2014, she felt uneasy about her fecal smell and saw a psychiatrist in the first part of January 2015. Quetiapine (25 mg/day) was added. In the last part of January, she complained of fecal smell everywhere and could not take a meal. No-one else could detect the smell. A diagnosis of olfactory hallucination was made. The next day after increasing to 75mg/day, however, she was admitted to our hospital because of refusing to take medicine. After introducing donepezil, olfactory hallucination subsided and her appetite was improved. Brain MRI showed atrophy of the bilateral temporal lobes and N-isopropyl-p-(iodine-123)-iodoamphetamine single photon emission computed tomography ( 123 I-IMP-SPECT) revealed hypoperfusion in the bilateral mesial temporal lobes. We suppose that cholinergic denervation in the mesial temporal lobes is an important determinant of her olfactory hallucination.

Purpose: A graph plot (GP) method using 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) has been proposed as a simple and non-invasive estimation of quantitative cerebral bloodflow (CBF). A regression equation for the GP method was estimated by the data of resting state. Therefore, the accuracy of CBF values in high flow range may be an underestimated possibility in this method.The aim of this study was to formulate a new regression equation for the GP method by the data of resting state and acetazolamide (ACZ) challenge, and to clarify the accuracy of it., Methods: The images of 26 consecutive patients who underwent both 123I-IMP chest radioisotope-angiography (RIA) and single photon emission computed tomography (SPECT) examinations were used to construct the new regression equation. Examinations of the resting state and ACZ challenge were performed in different days. All patients were analyzed by both the GP method and autoradiography (ARG) method which is the conventional examination with the one-point arterial blood sampling. A linear regression equation between the index of the input function was obtained by the GP method and CBF value of ARG. The linear regression equation based on the resting data was compared with the equation based on the resting and ACZ challenge (rest+stress) data., Results: Goodliner correlation was obtained between the index of the input function obtained by the GP method and CBF value of the ARG method in the rest+stress state (y=2.75x+15.1, r=0.78). In contrast, correlation results between the index of the input function obtained by the GP method and CBF value of the ARG method in the resting state was expressed as y=2.28x+18.4, r=0.54 rCBF values based on the resting data was 20% underestimated in the high flow range compared with values based on the rest+stress data., Conclusion: The new linear regression equation for the GP method is useful for clinical study. Key words: non-invasive cerebral blood flow measurement method, graph plot (GP), autoradiography (ARG), 123I-N-isopropyl-p-iodoamphetamine (123I-IMP).

In cerebral blood flow tests using N-Isopropyl-p-[123I] Iodoamphetamine "I-IMP, quantitative results of greater accuracy than possible using the autoradiography (ARG) method can be obtained with attenuation and scatter correction and image reconstruction by filtered back projection (FBP). However, the cutoff frequency of the preprocessing Butterworth filter affects the quantitative value; hence, we sought an optimal cutoff frequency, derived from the correlation between the FBP method and Xenon-enhanced computed tomography (XeCT)/cerebral blood flow (CBF). In this study, we reconstructed images using ordered subsets expectation maximization (OSEM), a method of successive approximation which has recently come into wide use, and also three-dimensional (3D)-OSEM, a method by which the resolution can be corrected with the addition of collimator broad correction, to examine the effects on the regional cerebral blood flow (rCBF) quantitative value of changing the cutoff frequency, and to determine whether successive approximation is applicable to cerebral blood flow quantification. Our results showed that quantification of greater accuracy was obtained with reconstruction employing the 3D-OSEM method and using a cutoff frequency set near 0.75-0.85 cycles/cm, which is higher than the frequency used in image reconstruction by the ordinary FBP method.

The aim of this study is to develop a non-invasive procedure for quantitative assessment of regional cerebral blood flow using IMP and SPECT. A technique to utilize a population-based standardized arterial input function has been evaluated for the normal data base obtained from 3 institutions, which employed different SPECT device configurations. In total, data from 39 subjects were analyzed. Due to the unique feature of the QSPECT reconstruction software program, images are quantitative providing units of Bq/ml. Thus, the well counter values can be converted to absolute radioactivity concentration. The blood-to-whole-body average partition coefficient was 343.8 +/- 65.0 and did not show significant difference among the three institutions. The estimated blood counts agreed with those assessed by the well counter in all institutions, thus the arterial input function can be estimated with the unique conversion factor for all institutions. This feature may allow a large scale multi-center investigation, which may contribute to improve the non-invasive protocol.

Purpose: The present study aims to quantitatively investigate a normal database (NDB) created under the same acquisition and reconstruction conditions for three gamma camera systems (four types of collimator systems) with use of three-dimensional stereotactic surface projections (3D-SSP). We rebuilt a NDB with use of the N-isopropyl-p-(123)I-iodoamphetamine ((123)I-IMP) SPECT data derived from 30 healthy individuals at 20 institutions nationwide. We standardized the acquisition and reconstruction conditions, evaluated Z scores using patient data (PD) and examined each compensation effect., Results: Z scores determined using the advanced NDB were the same value. Artifacts were often generated in Z score maps derived from the conventional NDB (CONDB). The Z score of the own site NDB (OWNDB) was 70% of that calculated based on the CONDB. The combinatorial difference in compensation (scatter and attenuation) resulted in many artifacts being generated in Z score map images., Discussions: More artifacts were generated in Z score map images using the novel NDB compared with the CONDB. The novel NDB was comparable to the performance of OWNB. The accuracy of brain function image analysis can be improved the reconstruction conditions and correcting for scatter and attenuation on both the novel NDB and PD.

The (123)I-IMP Graph Plot is a convenient method of analyzing cerebral blood flow without blood sampling. Data acquisition requires 45 minutes after the infusion of (123)I-IMP because the method is matched to the protocol of autoradiography (conventional method). However, we think that those protocols do not have to be matched because those theories are different. Therefore, we contrived a protocol for shortening that time by beginning SPECT data acquisition earlier and shortening the acquisition time compared to the conventional method. We compared count ratios of the decreased area to an area of the healthy side, quantitative values, and results of statistical analysis of the shortened protocol and the conventional method for cases of cerebral infarction and of dementia with Lewy bodies (DLB). Some count ratios of the shortened protocol were inferior to those of the conventional method, but the degrees did not affect the clinical diagnosis. In the other areas and cases also, the differences did not affect the clinical diagnosis. In addition to the results of this study, some previous reports have described that early SPECT images after infusion show the true cerebral blood flow. Therefore, we judged that this shortened protocol can be used as a clinical protocol.

Generally, the Chang method depends on counts for the attenuation correction (AC) method in brain perfusion single-photon emission computed tomography (SPECT), because the head outlined for a uniform attenuation coefficient map is set to the sinogram of the projection data by the threshold (Sinogram Threshold Chang method). Magnetic resonance imaging (MRI) is a routine examination in our hospital. Patients who underwent N-isopropyl-p-[(123)I] iodoamphetamine ((123)I-IMP) SPECT are undergoing MRI. Therefore, we thought it help AC accuracy to set an accurate head outline by using the image. We jointly made "Software for an attenuation coefficient map using MRI" for trial purposes. This paper investigated whether the AC method using MRI promotes the accuracy of brain perfusion SPECT in some clinical samples. With AC methods using gamma ray transmission computed tomography (TCT) or X-ray CT (CT) also being taken into account, the AC method using MRI was compared with the Sinogram Threshold Chang method. As a result, count dependency was excluded by an accurate head outline setting that used MRI, and the AC method using MRI approached the effect of the AC method using TCT and CT more than the Sinogram Threshold Chang method. Therefore, it is suggested that the AC method using MRI is useful for the accuracy of brain perfusion SPECT.

Purpose: We have previously reported the method of regional cerebral blood flow measurement using N-isopropyl-p-[123I]iodoamphetamine, in which the input function into brain was estimated from one-point venous blood sampling value based on the method of causality analysis between input and output functions. In the present study, we examined the effects of differences in blood sampling site and direction of static image collection on the accuracy of estimating input function using this method., Methods: The subjects consisted of 50 patients of right forearm venous sampling and 50 patients of left forearm venous sampling. As the static imaging directions, the following four combinations were compared 10 all four directions, 2) anterior and posterior directions, 3) right and left directions, and 4) an anterior direction. The accuracy of measurement was evaluated by comparing the estimated and directly measured value of input/output function (Caoct/Cvoct), and by the error indices and the correlation coefficients between the estimated and directly measured value., Result: In both groups of venous sampling, there was no significant difference between the estimated and directly measured value of Caoct/Cvoct. The error indices and correlation coefficient showed no significant difference between the right and left venous sampling groups. Similarly, no significant influence on Caoct/Cvoct value was observed by the difference of static imaging direction. Finally, the rCBF values calculated using these estimations were not significantly different from those by continuous arterial sampling method., Conclusions: These results indicate that both the difference in venous sampling site and the static imaging direction have little effect on the accuracy in our new method of rCBF measurement, and suggest its clinical versatility.

A 69-year-old man of thrombotic thrombocytopenic purpura (TTP) associated with ticlopidine was reported. The patient initially complained of dysarthria and left hemiparesis one month after oral administration of ticlopidine. These motor symptoms were followed by gradual deline in level of consciousness. On admission, he was in apallic state with focal cerebral signs, accompanied by low-grade fever, and purpuric eruptions. Laboratory findings showed remarkable thrombocytopenia, hemolytic anemia, and renal dysfunction. The patient received diagnosis of TTP based on Moschcowitzs criteria. Prompt initiation of plasma exchange dramatically improved the patient's clinical symptoms. In this case, decreased activities of a disintegrin and metallo proteinase with thrombospondin type 1 motifs 13 (ADAMTS13) in plasma and anti-ADAMTS13 IgG antibodies were detected. Serial diffusion weighted MRI with six-day interval starting from the onset showed two interesting findings. First, appearance and disappearance of scattered high intensity areas were observed in the cerebellum, corpus callosum, cerebral white matter, and neocortex. Second, these lesions roughly corresponded to border-zone infarct in distribution. Cranial MRI findings of TTP in the literature could be classified into the following four groups: 1) multiple infarction caused by microthrombi; 2) infarction caused by occulusion of an intracranial main artery; 3) reversible edema involving the cerebral white matter; and 4) unremarkable finding without specific abnormality. This case could be classified into the group 1. Based on the diffusion weighted MRI findings of this case, a previous pathological report and recent elucidations of clinical conditions, it is hypothesized that TTP is a predisposition for resembling the border-zone infarction in group 1. The border-zone distribution of transient high intensity areas in diffusion weighted MRI in this case could be explained by either high resistant vascules zone or impaired clearance of emboli, taking an autopsy case report into consideration.

Objective: Surgical revascularization for moyamoya disease prevents cerebral ischemic attacks by improving cerebral blood flow (CBF). But little is known about the changes of CBF and its effect on neurological status during the acute stage after direct bypass for moyamoya disease., Methods and Results: Perfusion-weighted magnetic resonance imaging (PWI) by the SE-EPI method was performed 4 and 10 days after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis on 11 sides of 9 patients (male:female = 2:7, 24-61 years old) with moyamoya disease. All patients underwent single-photon emission computed tomography (SPECT) 1 and 7 days after surgery. The time-to-peak (TTP) by PWI showed focal decrease at the site of the anastomosis 4 days after STA-MCA anastomosis compared to preoperative TTP, and was further decreased in larger territory 10 days after surgery in all patients. Postoperative cerebral blood volume (CBV) by PWI showed significant increase compared to preoperative CBV in four patients who suffered symptomatic cerebral hyperperfusion after surgery. Postoperative SPECT revealed apparent increase of CBF in all patients and the patency of the STA-MCA bypass was confirmed by MRA. All patients were discharged without neurological deterioration compared to preoperative neurological status, and none of them suffered ischemic attack after surgery., Conclusion: Postoperative decrease in TTP by PWI could be a sensitive parameter for the normalization of CBF after STA-MCA anastomosis in patients with moyamoya disease. Postoperative increase in CBV may suggest cerebral hyperperfusion and could be the optimal predictor for hyperperfusion syndrome after STA-MCA anastomosis in patients with moyamoya disease.

Objective: To investigate the correlation of the cognitive function and the duration of the illness with the regional cerebral blood flow (rCBF) in patients with Parkinson's disease (PD), by means of an objective diagnostic index of brain imaging, stereotactic extraction estimation (SEE) of 123I-IMP SPECT., Patients and Methods: We examined 123I-IMP SPECT in 24 patients with PD (age = 71.79 +/- 5.18 years; the Mini-Mental State Examination: MMSE score = 21.46 +/- 7.62 points; the duration of the illness = 6.63 +/- 3.91 years; Yahr scale = 3.29 +/- 0.74). A contrast database was created by averaging extracted database sets of the contrast group (numbers = 14 cases; age = 74.64 +/- 5.99 years, the MMSE score > or = 29 points). We applied SEE for Z-score images of three-dimensional stereotactic surface projection analysis (3D-SSP) for 123I-IMP SPECT, and calculated Z*extent ratio by taking advantage of severity of Z-score (the mean value) with extent ratio (%) in the frontal, occipital, temporal, parietal and posterior cingulate cortices, and precuneus, respectively. We investigated the correlation coefficient between the MMSE score and Z*extent ratio, and between the duration of the illness and Z*extent ratio in the six regions. In addition, we compared Z*extent ratio in the six regions between the non-demented group (numbers = 12 patients; MMSE > or = 24 points) and the demented group (numbers =12 patients; E score < or = 23 points)., Results: There were negative correlations between the MMSE score and Z*extent ratio in the temporal (p < 0.05) and posterior cingulate cortices (p < 0.05), and positive correlations between the duration of the illness and Z*extent ratio in the frontal (p < 0.01), temporal (p < 0.01), parietal (p < 0.05) and posterior cingulate cortices (p < 0.01). Z*extent ratio was significantly high only in the posterior cingulate cortex(p < 0.05) in the demented group., Conclusions: SEE for Z-score images of 3D-SSP revealed a close relationship between the decline of the MMSE score and the duration of the illness, and the perfusion reduction of the posterior cingulate cortex in patients with PD. These findings suggest that the perfusion reduction of the posterior cingulate cortex reflects the decline of cognitive impairment of patients with PD.

Dural arteriovenous fistulae(dAVF) in the anterior cranial fossa comprise about 6% of all dAVFs, and is usually detected after intracranial hemorrhage. However, non-hemorrhagic symptoms are uncommon. We encountered two patients with hemorrhagic and non-hemorrhagic dAVF in the anterior cranial fossa. Both cases were successfully treated using craniotomy and histopathological examination was performed. A 71-year-old male experienced sudden onset of nausea and headache, followed by progression of left hemiparesis and disturbance of consciousness due to intracerebral and subdural hematoma in 2005. Intracerebral venous aneurysm adjacent to the intracerebral hematoma originated from the draining cortical red vein was identified and successfully treated by operation. Histopathological examination revealed disappearance of the internal elastic lamina and scant muscle tissue in the venous aneurysmal wall originating from draining cortical vein. A 69-year-old male suffered sudden onset of mild headache, followed by progression of bruits in 2005. MRI suggested dAVF in the left anterior cranial fossa. 123I-IMP SPECT revealed an area of low perfusion in the left frontotemporal region. Histopathological examination after surgical treatment revealed thickening of the intima and an indistinct lamina elastica interna, indicating progressive degenerative changes of the arterialized vein likely to result in hemorrhage. Surgical obliteration of fistulae is reasonable even in the dAVF of the anterior cranial fossa with ischemic onset.

Single photon emission computed tomography (SPECT) was performed 3 times during attacks and performed 4 times during postictal periods on a case of alternating hemiplegia of childhood. Hyperperfusion of the corresponding hemisphere to hemiparesis was suggested by asymmetric increase RI uptake during the ictal scans, whereas interictal scans showed symmetric topography of cerebral blood flow. Manifestations except hemiplegia included loss of consciousness and vomiting. These manifestations and ictal SPECT findings are the same evidence as hemiplegic migraine. It suggests that these two disorders have a similar pathophysiology. There are two interesting findings regarding this patient. The first finding is magnetic resonance imaging showed progressive cerebellar atrophy. Second finding is interictal SPECT showed a progressive decrease of cerebral perfusion, especially in cerebellar hemispheres. These two findings suggest alternating hemiplegia of childhood may be a chronic progressive disorder.

There has been a controversy as to the contribution of the frontal lobe to human memory function. We describe a 49-year-old right-handed patient with memory disturbance following a left medial frontal subcortical hematoma. Her amnesia was characterized by (1) predominant anterograde amnesia, (2) difficulty in both voluntary recall and recognition tasks, (3) a great number of false-alarm responses in a recognition task, and (4) no confabulation. An MRI demonstrated that her lesion was restricted to the left medial frontal area and anterior cingulate gyrus. This case represents a rare instance of amnesia following damage to the frontal lobe. We speculated that the unique feature of her memory impairment resulted from combined lesions in the medial frontal subcortical white matter and anterior cingulate gyrus. It seems that Papez's circuite participated in the development of these symptoms.

A 29-year-old man was admitted because of sudden onset of retrograde amnesia. The patient was unable to recall events having occurred during the past 2 years. The impairment was especially serious with regard to personal memories during the 5 months prior to admission, while he had first been working as a full-time employee under stressful circumstance. A diagnosis of dissociative amnesia was made on the basis of absence of any systemic or neurological diseases that could cause amnesia, the inadaptable character of the patient, the nature of amnesia, and presence of stressful condition possibly related to the amnesia. Visual event-related potential (ERP) studies recorded with human face discrimination tasks demonstrated a P3a wave in response to a face of his superior in the office, whom he said that he had never seen before. The similar P3a wave was observed in response to a face quite familiar to the patient, his mother, but not to a face "truly" unknown to him. These findings suggest that the visual memory of his superior's face exists in the brain, but the patient is unable to retrieve it by some psychogenic mechanism. 131I-IMP SPECT revealed decreased perfusion in the left medial temporal lobe and the basal forebrain, suggesting the association between dissociative amnesia and focal brain dysfunction. While dissociative amnesia has been understood as psychogenic nature, both ERPs and SPECT are quite important tools to understand the association between the psychological phenomenon and biological changes of the brain in this disorder.

There is increasing evidence that stenting is a useful strategy for internal carotid artery (ICA) stenosis in patients unfit for drastic surgery. However, it should be remembered that perioperative complications including seizure or intracerebral hemorrhage due to hyperperfusion are not so rare. The authors describe a case with severe ICA stenosis, who successfully underwent stenting as a result of intensive medical care for postoperative hyperperfusion. A 77-year-old man with a recent history of angina pectoris and transient ischemic attack was referred to our hospital. Cerebral angiography showed subtotal occlusion of the left ICA. SPECT/PET studies revealed a disturbed reactivity to acetazolamide and an increase in regional oxygen extraction fraction in the left hemisphere, suggesting a marked reduction in cerebral perfusion pressure. He successfully underwent carotid stenting. Intraoperative near-infrared monitoring showed an increase in the concentration of total and oxidized hemoglobin in the left frontal area after stenting. A SPECT study just after stenting also demonstrated hyperperfusion in the left middle cerebral artery territory. His blood pressure was carefully controlled to avoid "hyperperfusion syndrome" including headache, seizure and intracerebral hemorrhage. Follow-up SPECT/PET studies showed a normalization of hemodynamic and metabolic parameters. SPECT/PET studies are quite valuable to predict and prevent hyperperfusion syndrome after carotid stenting, and result in good clinical outcome.

Isolated angiitis of the central nervous system (IAC) is an inflammatory, rare vasculopathy confined to the central nervous system, and the exact etiology has remained uncertain. We report serial changes in the vasculature and the mean cerebral blood flow (mCBF) in two patients with IAC. The first patient, a 58-year-old female, had sudden onset of severe headache and CT 4 days later showed cerebral hemorrhage in the frontal lobe. MRA revealed that the main trunks were dilated on admission, whereas two weeks later, diffuse narrowing of affected arteries occurred in multiple vascular distributions. She required about two months for almost full recovery in MRA findings. Mean CBF during the period of vascular narrowing did not correlate with the form of vasculature, and was much the same as that in the chronic phase. The second patient, a 24-year-old female, presented with severe headache one day after delivery following an uncomplicated pregnancy. MRA findings showed that, at first, segmental stenoses were located only in the peripheral regions of the middle cerebral artery, but this vascular abnormality spread to the anterior, middle and posterior cerebral arteries. She showed almost full recovery in MRA findings after about 3 months. SPECT analysis showed approximately 35% decrease in mCBF compared with that in the chronic phase. In the first case, hyperemia, which was caused by inflammatory cells infiltrating into the brain parenchyma through the vessel wall, contributed to cerebral hemorrhage. On the other hand, in the second case it was presumed that because inflammation was restricted to the vascular wall, mCBF consequently correlated with the form of vasculature. Our experience suggests that IAC has several etiologies.

We investigated the regional cerebral blood flow (rCBF) in 8 patients with Parkinson disease (PD) with cognitive impairment (age; 64-82 years, Mini-Mental State Examination score = MMSE score; 22-6 points, Yahr stage; III-V), with the standard transaxial images and the Z-score images using the three-dimensional stereotactic surface projections (3D-SSP) of 123I-IMP SPECT. A contrast database was created by averaging extracted database sets of the contrast group (numbers; 14 cases, age; 64-82 years, MMSE score; > or = 29 points). The regions of the perfusion reduction shown on the standard transaxial images were similarly demonstrated on the Z-score images in 6 of the 8 patients, and only the Z-score images demonstrated definite regions of perfusion reduction in remaining 2 patients. Both the standard transaxial and Z-score images demonstrated the perfusion reduction in the temporo-parietal regions in all of the patients, and the Z-score images but not the standard transaxial ones detected the reduction in the posterior cingulate gyrus and precuneus in 3 patients. 3D-SSP images of 123I-IMP SPECT are thus more sensitive in detecting rCBF of the medial aspect of the parietal cortex than the standard transaxial images, and can be used as a diagnostic tool to objectively evaluate the cognitive function of PD patients.

Migraine is usually not associated with CSF pleocytosis. However, patients with migraine-like severe headache who showed temporary neurological deficits and pleocytosis have recently been accumulated in the literature. Here we report a 20-year-old woman who was admitted to our hospital because of aphasia and right hemiparesis with severe throbbing headache in the left on 15 February, 2001. During the preceding 3 days she experienced another two similar episodes. Lumbar puncure revealed lymphocyte dominant pleocytosis of 56 cells/microliter. These symptoms recovered completely within several hours. EEG showed intermittent theta waves of 4-5c/s, 50-80 microV in the bilateral fronto-parietal region, but no epileptiform activity. On the 12th day 123I-IMP SECT demonstrated rather hyperperfusion in the left fronto-temporo-parietal region. Again, in the early morning on 10 December she was carried to our hospital by an ambulance car because of severe headache, right hemiparesis, expressive and receptive aphasia and drowsiness. Body temperature was 37.9 degrees C and lumbar puncture revealed increased opening pressure of 230 mmH2O and cells of 17/microliter. All the symptoms cleared within 24 hours and she left hospital without any sequelae. The symptoms of this case are consistent with those of headache with neurologic deficits and CSF lymphocytosis (HaNDL) by Berg et al, or pseudomigraine with pleocytosis (PMP syndrome) by Gometz-Aranda et al. No reports have been published on this disease in Japan.

We studied regional cerebral blood flow (rCBF) in 16 patients with Parkinson's disease (PD), 2 patients with dementia with Lewy bodies (DLB), 2 patients with progressive supranuclear palsy (PSP), 2 patients with striatonigral degeneration, and 16 normal volunteers, using Three-dimensional stereotactic surface projections (3 D-SSP). Decreased rCBF in PD patients was shown in the posterior parietal and occipital cortex. Decreased rCBF in DLB was shown in the frontal, parietal and occipital cortex with relative sparing of the sensorimotor cortex. Decreased rCBF in PSP was shown in the frontal cortex. Decreased rCBF in SND was shown in the frontal cortex and cerebellum. Statistic rCBF analysis using 3 D-SSP was a useful measure for the early differential diagnosis of extrapyramidal disorders.

Purpose and Methods: The noninvasive microsphere (NIMS) method quantifies cerebral blood flow with N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) without blood sampling of a patient, but when a fan beam collimator is used for collecting raw data in single photon emission computed tomography (SPECT), the procedure is complicated because we have to change the collimator. In phantom and clinical studies we investigated the validity of using a fan beam collimator in collecting planar and SPECT raw data., Results: The phantom study suggested that using a fan beam collimator for planar imaging was feasible because of the image magnification rate and the count rate. Mean cerebral blood flow (mCBF) values obtained by the NIMS method with the fan beam collimator were compared with mCBF simultaneously estimated from the conventional continuous arterial blood sampling (microsphere: MS) method in twenty patients with ischemic cerebral vascular diseases. There was good correlation (y = 1.033x + 8.004, r2 = 0.729, p < 0.01) in mCBF between the fan beam NIMS method and the MS method., Conclusion: In conclusion, this method for the measurement of CBF was acceptable for routine clinical studies.

Machado-Joseph disease (MJD) is an autosomal dominant spinocerebellar ataxia. Its clinical features vary greatly in different generations of the same family. Regional cerebral blood flow (rCBF) and distribution volume (Vd) in the pons, cerebellum, and cerebral cortex were measured in 12 patients with MJD by autoradiography (ARG) and the table look-up (TLU) method of iodine-123 IMP (123I-IMP) single photon emission computed tomography (SPECT). Representative cases were as follows: A 46-year-old woman first experienced gait ataxia at age 38. Computed tomography (CT) and magnetic resonance imaging (MRI) showed no atrophy in the pons or cerebellum, but rCBF measured by the 123I-IMP SPECT ARG method detected hypoperfusion in the pons, and cerebellar vermis and hemisphere. A 76-year-old woman first experienced gait ataxia at age 69. CT and MRI findings showed severe atrophy in the pons, and cerebellar vermis and hemisphere. Moreover, rCBF was decreased in the pons, whereas it was not decreased in the cerebellar vermis and hemisphere. In the pons of patients with MJD, rCBF was markedly decreased regardless of disease severity. Because this SPECT finding for the pons looked like a 'dot', we have called it the 'pontine dot sign'. In the MJD group, rCBF was significantly decreased in the pons (Student's t test, p < 0.01) and cerebellar vermis (p < 0.05). The Vd was also significantly decreased in the pons (p < 0.005) in comparison with that for normal subjects. Pearson's correlation analysis yielded a significant relationship between the rCBF in the pons and age at onset (r = 0.578, p < 0.05). There was a strong correlation between the Vd for the pons and age at onset (r = 0.59, p < 0.05). Pearson's correlation analysis also showed a significant relationship between the Vd in the cerebellar hemispheres and International Cooperative Ataxia Rating Scale (r = 0.644, p < 0.05). The pontine rCBFs in patients with early onset MJD, whose pons was not atrophic, decreased more than did those in patients with late onset MJD, whose pons was severely atrophic. This suggests that the SPECT findings are indicative of underlying neurodegenerative processes that began before the onset of clinical symptoms. Different processes seem to function in atrophy and the rCBF decrease in the pons of patients with MJD. These findings will be proved by the increase of the number of cases of MJD. Until now, there has been no report on rCBF and Vd obtained by 123I-IMP SPECT for patients with MJD identified by gene analysis. Our study shows that SPECT measurement of rCBF and Vd is useful for understanding the pathophysiology of MJD.

We conducted a neuropsychological comparison between Parkinson's disease (PD; n = 24) and healthy control subjects (n = 12) using Rey's auditory-verbal learning test (RAVLT) and the Rey-Osterrieth complex figure test (RCFT) assessing memory function. In addition, to determine the function of cortical and subcortical areas, we measured the regional cerebral blood flow (rCBF) using N-isopropyl-p[123I]-iodoamhetamine (123I-IMP) and single photon emission computed tomography (SPECT) and analyzed the relationships between brain regions and memory function. On the RAVLT, significant group differences in recall words were found on all learning trials between patients with PD and control subjects, whereas recognition, learning rate and forgetting rate were basically the same. In addition, the primacy/recency effect was statistically equal for both groups. Results suggest faulty retrieval mechanisms in PD, whereas encoding and retention procesess did not prove to be affected. There were significant correlations between perfusion of the prefrontal and parietal cortices and total number of free recall in five trials. On the RCFT, recalls after 30 sec and 30 min were impaired in patients with PD although no significant difference in accuracy scores obtained in copy was noted. A percent recall score calculated using the formula 100 x [1 - (copy-recall)/copy] was also decreased in patients with PD. There were significant correlations between perfusion of the occipital and parietal cortices and percent recall score. Our data suggest that auditory memory deficits based on the RAVLT in PD may be mainly related to frontal and parietal cortical dysfunction, while visual recall deficits based on the RCFT may be related to the parieto-occipital cortical dysfunction.

We presented a patient of paradoxical embolism with Chiari network, subsequently being accompanied by probable incomplete infarction. This 21-year-old man suffered from consciousness disorder, aphasia and right hemiparesis, and hospitalized in November 6, 1999. Magnetic resonance imaging showed mixed intensity on T1 and T2-weighted images in part of the areas of the left anterior and middle cerebral arteries. Cerebral angiography revealed the early venous fillings and the capillary blushs. These findings implicated stroke in young adult. Still more transcranial color-flow imaging showed high intensity transient signals with "Chirp" sounds on the left middle cerebral artery. Transesophageal echocardiography detected Chiari network. Chiari network was thought the course of cerebral infarction. Over again 123I-IMP single-photon emission CT findings revealed the marked reduction of his cerebral blood flow comprehensively in the left hemispherium. It was suggested that the recanalization after the paradoxical cerebral embolism had caused incomplete infarction.

To examine the difference in functional brain imaging between mild cognitive impairment (MCI) and normal aging, we measured rCBF on functional brain imaging using 123I-IMP single photon emission computed tomography (IMP-SPECT) in 19 MCI patients who progressed to develop AD on follow-up and 23 probable Alzheimer's disease (AD) patients as well as 15 age-matched normal subjects. Baseline MMSE score was 25.3 (SD 1.2) in the MCI group and 17.5 (SD 3.3) in the AD group. The regions of interest (ROI) in the posterior cingulate gyrus, frontal, temporal and parietal cortices were drawn on the image of IMP-SPECT with reference to an individual MRI image. The rCBF ratio was calculated using ROI value in the cerebellum as a reference. Voxel-based analysis was also preformed using statistical parametric mapping (SPM). The rCBF ratio in the posterior cingulate gyrus was significantly reduced in the MCI group (mean 0.956, SD 0.080) and the AD group (mean 0.833, SD 0.118) compared to that in the normal group (mean 1.083, SD 0.084). In the frontal, temporal and parietal cortices, the rCBF ratio was significantly reduced only in the AD group compared to the normal group. At a fixed specificity of 80%, the diagnostic sensitivity in the discrimination between MCI patients and normal subjects was 80.5% when using rCBF ratio in posterior cingulate gyrus. In the SPM analysis, significant reduction of the rCBF in MCI group was observed only in the posterior cingulate gyrus, compared with normal subject group. Our results suggest that MCI patients presenting with a posterior cingulate hypoperfusion are at higher risk for transition from MCI to clinically recognizable AD.

It is important for dural arteriovenous fistula (DAVF) to evaluate venous ischemia in the brain related to venous hypertension, but only a few such studies have been performed. In this study, regional cerebral blood flow(rCBF) in DAVF was examined for venous ischemia by 123I-IMP SPECT. The subjects were eighteen patients with DAVF. Of the eighteen patients, nine had DAVF with low perfusion areas and venous ischemia. The factors affecting rCBF in DAVF are: 1) the presence of retrograde leptomeningeal venous drainage, 2) sinus occlusion, and 3) DAVF with high flow. The presence of retrograde leptomeningeal venous drainage was observed in nine patients, sinus occlusion in four patients, high flow in three patients. In two patients, pure leptomeningeal venous drainage was formed by patent sinus, and blood regurgitated from DAVF on the sinus wall to cortical vein. When DAVF was associated with LMVD, most patients had venous hypertension and concomitant venous congestion in the same areas due to reduced venous circulation, resulting in a decrease in rCBF and an increase in regional cerebral blood volume. These hemodynamics suggest venous ischemia in the brain. 123I-IMP SPECT was useful for evaluating rCBF and as a parameter of the treatment.

Brain SPECT studies are used to evaluate the cerebral hemodynamic changes in cerebrovascular diseases and other neuro-psychiatric disorders. I-123 and Tc-99m labeled radiopharmaceuticals widely used for brain perfusion SPECT studies include I-123 IMP, Tc-99m HMPAO, and Tc-99m ECD. I-123 IMP is suitable for the quantitative evaluation of cerebral blood flow, while Tc-99m HMPAO and Tc-99m ECD have problems owing to the non-linearity between cerebral radioactivity and cerebral blood flow. In addition, Tc-99m ECD does not show cerebral blood flow in the subacute phase of cerebral infarct or other conditions. Thus, it is important to consider the characteristics of radiopharmaceuticals and the clinical aspect of brain lesions in the interpretation of brain perfusion SPECT images. In this review, some useful information on brain perfusion SPECT is presented mainly as it relates to the cerebrovascular diseases.

A 22-year old woman developed erythema in her hands. She also suffered from general fatigue and arthralgia. In July of 1992, she visited the dermatology clinic of Nagoya City University Hospital. We made a diagnosis of subacute cutaneous lupus erythematosus with thrombocytopenia and gave her 30 mg of prednisolone daily. Her conditions were improved and had been stable with 5 mg of prednisolone daily. In the winter of 1993, she developed ulcer in her fingers and soles. These lesions were associated with antiphosholipid syndrome. She complained of mild headache. She was examined by CT, MRI and single photon emission computerized tomography (SPECT) using N-isopropyl-p-[123I] iodoamphetamine (IMP). Low perfusion areas in the bilateral occipital lobes and the right temporal lobe were found in SPECT, although no abnormalities were detected by CT and MRI. Low perfusion areas in antiphospholipid syndrome might be caused by microarterial thrombosis, microvenous thrombosis or spasms, although they could be reversible. Ten mg of argatroban daily for one month improved cerebral low perfusion, headache, and skin lesions. In this case, argatroban was effective for both cerebral low perfusion and skin ulcer, which were related to antiphospholipid syndrome.

The authors report the case of a 35-year-old male who underwent stenting for spontaneous cervical carotid dissection. He presented with sudden onset of hemicrania and left facial palsy followed by left hemiparesis and dysarthria. On admission, carotid angiography revealed postsinus tapering occlusion of the right internal carotid artery. Initially, he was managed with conservative treatment, but his neurological status deteriorated. Findings of brain CT, MRI and IMP-SPECT suggested hypoperfusion of the right cerebrum. A Palmaz stent, 39 mm in length, was successfully placed over the site of the dissection to restore normal patency through the dissected carotid artery. Following stent implantation, his neurological signs improved gradually but completely. Since the procedure, with oral administration of antiplatelet medication, he has suffered no cerebral ischemic events. Follow-up carotid angiography one year after stent implantation showed good patency of the stented segment. The present case emphasizes the usefulness of stenting for spontaneous cervical carotid dissection.

In our previous paper regarding determination of the regional cerebral blood flow (rCBF) using the 123I-IMP microsphere model, we reported that the accuracy of determination of the integrated value of the input function from one-point arterial blood sampling can be increased by performing correction using the 5 min: 29 min ratio for the whole-brain count. However, failure to carry out the arterial blood collection at exactly 5 minutes after 123I-IMP injection causes errors with this method, and there is thus a time limitation. We have now revised our method so that the one-point arterial blood sampling can be performed at any time during the interval between 5 minutes and 20 minutes after 123I-IMP injection, with addition of a correction step for the sampling time. This revised method permits more accurate estimation of the integral of the input functions. This method was then applied to 174 experimental subjects: one-point blood samples collected at random times between 5 and 20 minutes, and the estimated values for the continuous arterial octanol extraction count (COC) were determined. The mean error rate between the COC and the actual measured continuous arterial octanol extraction count (OC) was 3.6%, and the standard deviation was 12.7%. Accordingly, in 70% of the cases, the rCBF was able to be estimated within an error rate of 13%, while estimation was possible in 95% of the cases within an error rate of 25%. This improved method is a simple technique for determination of the rCBF by 123I-IMP microsphere model and one-point arterial blood sampling which no longer shows a time limitation and does not require any octanol extraction step.

The present study was designed to investigate a possibility of substitution of the venous blood radioactivity counts sampled 26 min post injection for the octanol-extracted arterial blood radioactivity counts obtained at 5 min after the injection of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). Furthermore, we investigated whether the integral of input function can be estimated from the venous blood radioactivity counts sampled 26 min post injection and the whole-brain time-activity curves early after 123I-IMP injection. There was a good correlation between the arterial blood radioactivity counts sampled 5 min post injection (y) and those obtained at 26 min (r = 0.902; n = 91; y = 2.348x - 867.063). There was also a good correlation between the arterial (x) and venous blood radioactivity counts (y) sampled 26 min post injection (r = 0.954; n = 14; y = 0.761x + 924.336). The venous blood radioactivity counts sampled at 26 min (x) correlated well with the octanol-extracted arterial blood radioactivity counts sampled at 5 min (y) (r = 0.964; n = 32; y = 0.173x - 21.598). There was a good correlation between the integrals of input function obtained from the regression equation obtained above and the whole-brain time-activity curves acquired during 7 min post injection (y) and those obtained by 5-min continuous arterial blood sampling (x) (r = 0.965; n = 41; y = 0.957x + 2665.208). These results indicate that this noninvasive and simple method can estimate the integral of input function for quantification of cerebral blood flow using 123I-IMP.

Cerebral blood flow was quantitatively measured using 123I-IMP SPECT by photic stimulation and visual evoked potential (VEPs) in normal and dementia subjects: 8 with Alzheimer-type dementia, 9 with cerebrovascular dementia and 7 normal elderly subjects were divided into the three groups based on the Clinical Dementia Rating (CDR) grade: Group I (CDR 0), Group II (CDR 0.5-1), Group III (CDR 2-3). The 123I-IMP SPECT measurement was conducted at rest with the eyes closed and also during photic stimulation. VEPs were measured simultaneously. The results reveal prolongation of the P2 latency of the VEPs prolonged in accordance with the increasing severity of the dementia, and quantitative cerebral blood flow was lower in Group II and Group III than in Group I at rest, while during photic stimulation it significantly increased in Group I and II, but showed no change in Group III. The results suggest that quantitative measurement of cerebral blood flow using 123I-IMP SPECT by photic stimulation may enable more detailed assessment of brain cell function.

In order to avoid continuous arterial blood sampling, we estimated input function by the method in that the whole brain time activity curves were fitted by two-term exponential function and differentiated analytically after the injection of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP). This method was applied to 4 patients with cerebral infarction and 2 patients with brain tumor. Values of regional cerebral blood flow (rCBF) were calculated from the input function calibrated by one-point arterial sampling at 5 minutes after the injection using microsphere method, and then were compared with those obtained from the table-lookup method. In this study, we used the individual input function for the table-lookup method instead of the standard input function. The overall accuracy errors between two-term exponential functions and the whole brain time-activity curves were about 1%. The values of rCBF calculated by this method were well correlated with those by the table-lookup method (r = 0.901, p < 0.001). Optimal calibration time for this method was between 3-minute and 10-minute after 123I-IMP injection and the deviation of the rCBF values obtained by this method from those obtained by the table-lookup method in which the input function was calibrated at 5 minutes remained within 10%. This method is a less invasive and convenient alternative to the conventional methods which require continuous arterial blood sampling.

Statistical parametric mapping (SPM) has been developed by Friston et al. to analyze focal changes in regional cerebral blood flow (rCBF) induced by brain activation. This automated and objective approach has the potential of being applied to single photon emission computed tomography (SPECT) image data sets. This study evaluated an automated analysis of N-isopropyl-p[123I]iodoamphetamine SPECT (123I-IMP) imaging in patients with dementia of Alzheimer's type (DAT) using statistical parametric mapping '95 (SPM'95). Eighteen patients with clinically diagnosed mild to severe DAT who were classified into two groups and ten normal control subjects were studied. The SPECT device used was a triple-headed rotation gamma camera. All images were transformed into the standard anatomical space of the stereotaxic brain atlas of Talairach and Tournoux, and then smoothed. Statistical analyses were made between severe DAT, mild DAT and normal control groups. SPM analysis of 123I-IMP SPECT images revealed that the parietotemporal association areas and posterior cingulate gyri of both cerebral hemispheres were significantly decreased in CBF in mild DAT group compared to normal controls. In comparison of DAT groups, the right hippocampal area and basal forebrain were significantly decreased in CBF in severe DAT group. In conclusion, these results obtained by SPM analysis of SPECT images suggested that the right hippocampal area and basal forebrain followed the parietotemporal association areas and posterior cingulate gyri in the reduction of the rCBF in patients with DAT.

A case of choroidal malignant melanoma in which N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) scintigraphy was useful for diagnosis is reported. A 62-year-old man first visited our hospital 3 years ago complaining of decreases in left eyesight. CT showed a tumor with an arcuate high attenuation area on the aural side of the optic disk in the left eye. A crescent high attenuation area, evidence of retinal detachment, was also observed on the nasal side of the optic disk. T1-weighted MR images showed low signal intensity in most of the tumor and a high signal intensity area was seen in the center, T2-weighted MR images showed homogeneous and marked low signal intensity area. Differentiation from a hematoma or a vascular tumor associated with bleeding was impossible based on CT and MRI. However, because late-phase images obtained on 123I-IMP scintigraphy showed marked high accumulation in an area corresponding to almost the entire left eye, left eye enucleation was undertaken under a diagnosis of malignant melanoma. Histopathologic examinations showed tumor growth mainly in the subretinal area. The melanin content of the tumor was high in the periphery and relatively low in the center. Infiltration was observed into the sclera and around the vortex vein outside the eyeball, but this change could not be detected by CT or MRI. 123I-IMP scintigraphy was useful not only for qualitative diagnosis of choroidal malignant melanoma, but for the determination of the extent of the lesion as well.

A correction method was proposed for measurement of the regional cerebral blood flow using one-point arterial blood sampling and a microsphere model with N-isopropyl-p-(123I)iodoamphetamine (123I-IMP). Instead of using continuous arterial blood sampling octanol-extracted counts, one-point arterial sampling whole blood counts corrected by the whole brain count ratio using 1-minute planar SPECT images were employed. The experimental subjects were 189 patients with cerebrovascular disorders. 123I-IMP, 222 MBq, was administered by intravenous infusion. Continuous arterial blood sampling was carried out for 5 minutes, and arterial blood was also sampled once at 5 minutes after 123I-IMP administration. Then the whole blood count of the one-point arterial sampling was compared with the octanol-extracted count of the continuous arterial sampling. A positive correlation was found between the two values (r = 0.87, p < 0.001). The correction method was carried out by calculation as follows. The ratio of the continuous sampling octanol-extracted count (OC) to the one-point sampling whole blood count (TC5) was compared with the whole brain count ratio (5:29 ratio, Cn) using 1-minute planar SPECT images, centering on 5 and 29 minutes after 123I-IMP administration. Correlation was found between the two values (r = 0.72, p < 0.001). The following relationship was shown from the correlation equation. OC/TC5 = 0.390969 x Cn-0.08924. Based on this correlation equation, we calculated the theoretical continuous arterial sampling octanol-extracted count (COC). COC = TC5 x (0.390969 x Cn-0.08924). There was good correlation between the value calculated with this equation and the actually measured value (r = 0.94, p < 0.001). The coefficient improved to r = 0.94 from the r = 0.87 obtained before using the 5:29 ratio for correction. For 23 of these 189 cases, another one-point arterial sampling was carried out at 6, 7, 8, 9 and 10 minutes after the administration of 123I-IMP. The correlation coefficient was also improved for these other point samplings when this correction method using the 5:29 ratio was applied. It was concluded that it is possible to obtain highly accurate input functions, i.e., calculated continuous arterial sampling octanol-extracted counts, using one-point arterial sampling whole blood counts by performing correction using the 5:29 ratio.

We assessed the regional cerebral blood flow (rCBF) in 8 patients with subcortical aphasia and 8 patients with subcortical infarction without aphasia using the N-isopropyl-P-[123I]-iodoamphetamine autoradiography (123I-IMP ARG) method. In this study, we evaluated vermis to left cortex ratio of CBF. In cases of Broca's aphasia (N = 2), CBF was lower in the posterior frontal regions including Broca's area, and more hypoperfused in the posterior frontal and in the posterior temporal regions, including Wernicke's area of total aphasia (N = 2). But, it was not significantly hypoperfused in those regions in the cases of Wernicke's (N = 2) and amnestic aphasia (N = 2). In the subcortical aphasia, global CBF in the left cerebral cortex was lower than that in the right cerebral cortex. However, in the subcortical infarction group without aphasia there was no difference between CBF in the left cerebral cortex and the right cerebral cortex. We conclude that hypoperfusion in the left cerebral cortex was greater than that in the right cerebral cortex and it was probably due to dysfunction of the left cerebral cortex when subcortical infarction occurred with aphasia. Though some types of aphasia were not relative to the dysfunction of the left cerebral cortex.

A noninvasive microsphere method using N-isopropyl-p-[123I]iodoamphetamine (123I-IMP), developed by Yonekura et al., was performed in 10 patients with neurological diseases to quantify regional cerebral blood flow (rCBF). Regional CBF values by this method were compared with rCBF values simultaneously estimated from both the modified fractional uptake (FU) method using cardiac output developed by Miyazaki et al. and the conventional method with continuous arterial blood sampling. In comparison, we designated the factor which converted raw SPECT voxel counts to rCBF values as a CBF factor. A highly significant correlation (r = 0.962, p < 0.001) was obtained in the CBF factors between the present method and the continuous arterial blood sampling method. The CBF factors by the present method were only 2.7% higher on the average than those by the continuous arterial blood sampling method. There were significant correlation (r = 0.811 and r = 0.798, p < 0.001) in the CBF factor between modified FU method (threshold for estimating total brain SPECT counts; 10% and 30% respectively) and the continuous arterial blood sampling method. However, the CBF factors of the modified FU method showed 31.4% and 62.3% higher on the average (threshold; 10% and 30% respectively) than those by the continuous arterial blood sampling method. In conclusion, this newly developed method for rCBF measurements was considered to be useful for routine clinical studies without any blood sampling.

We studied the accuracy of the method for measuring regional cerebral blood flow (rCBF) loaded with acetazolamide based on the microsphere model using iodine-123-IMP (IMP) SPECT. Two methods were examined, the super-early microsphere method with continuous withdrawal of arterial blood using the SPECT image obtained 5 min after tracer injection and the early microsphere method with one-point arterial sampling using the SPECT image obtained 30 min postinjection. On five subjects, after acetazolamide administration we measured rCBF by the analysis based on the two-compartment model using the data derived from dynamic SPECT scans and the sequential arterial blood sampling after IMP injection. Values of rCBF obtained by both super-early microsphere method and early microsphere method were significantly correlated with those obtained by the two-compartment model analysis (r = 0.982, 0.930, respectively). We conclude that it is possible to use the method based on the microsphere model in measuring rCBF loaded with acetazolamide. The early microsphere method with one-point sampling should be used clinically because of its simplicity and less-invasiveness.

Excellent results of multiple burr-hole operation (MBHO) for child moyamoya disease are reported in this study. Three patients of moyamoya disease had MBHO. After MBHO, transient, ischemic attacks disappeared in a patient despite progressing stenosis of the major cerebral arteries, and remarkable neurological improvement was recognized in a patient who had encephaloduroarteriosynangiosis. Another patient slowly improved and became able to go to junior high school. N-isopropyl-p-[123I] iodoamphetamine (IMPSPECT) findings also improved in all patients. There was no mortality or morbidity, and no new neurological deficits or bleedings developed during the follow up period. The authors recommend the MBHO as the surgical treatment of choice for not only adult but also child moyamoya disease because of its safety and effectiveness, and also report the usefulness of MBHO for the patients who have already received other bypass operations.

Radiotracers called chemical microsphere are widely accepted as brain perfusion agents. Following the intravenous administration, these drugs are transported via the artery to the brain, cross the intact blood-brain barrier, and enter the brain tissue. Once the tracer flows into the brain, the efflux of the tracer is prevented by some trapping mechanism, resulting in prolonged retention. Because the distribution of the accumulated tracer remains approximately consistent with regional cerebral blood flow for a relatively long period, high-quality SPECT images reflecting the distribution pattern of cerebral blood flow can be acquired. However, unlike true microsphere, cerebral kinetics of the brain perfusion agents is complicated, and various causes may produce discrepancy between the distributions of the tracer and blood flow. In this review, cerebral kinetics of the brain perfusion agents used commonly is discussed. The knowledge of the mechanism of brain accumulation appears to be essential to appropriately determine the tracer of choice and interpret the obtained images.

Attenuation correction for cerebral blood flow SPECT image reconstruction is usually performed by considering the head as a whole to be equivalent to water, and the effects of differences in attenuation between subjects produced by the cranium have not been taken into account. We determined the differences in attenuation between subjects and assessed a method of correcting quantitative cerebral blood flow values. Attenuations by head on the right and left sides were measured before intravenous injection of 123I-IMP, and water-converted diameters of both sides (Ta) were calculated from the measurements obtained. After acquiring SPECT images, attenuation correction was conducted according to the method of Sorenson, and images were reconstructed. The diameters of the right and left sides in the same position as the Ta (Tt) were calculated from the contours determined by threshold values. Using Ts given by 2Ts = Ta - Tt, the correction factor gamma = exp (mu(1)Ts) was calculated and multiplied as the correction factor when rCBF was determined. The results revealed significant differences between Tt and Ta. Although no gender differences were observed in Tt, they were seen in both Ta and Ts. Thus, interindividual differences in attenuation by the cranium were found to have an influence that cannot be ignored. Inter-subject correlation is needed to obtain accurate quantitative values.

Statistical parametric map (SPM) has been developed by Friston et al. to analyze focal changes in rCBF induced by brain activation. This automated and objective approach has the potential of being applied to SPECT image data sets. This study evaluated an automated analysis of brain SPECT imaging in patients with dementia of Alzheimer type (DAT) using SPM95. Seventeen patients with clinically diagnosed moderate to severe DAT and nine normal control subjects were studied. The SPECT device used was a triple-headed rotation gamma camera GCA9300A/HG. All images were transformed into the standard anatomical space of the stereotactic brain atlas of Talairach and Tournoux, and then smoothed. Statistical analysis was made between DAT and normal control groups. SPM analysis of SPECT images revealed that the parieto-temporal areas and posterior cingulate gyrus of both cerebral hemispheres were significantly decreased in DAT patients compared to normal controls. In conclusion, SPM analysis of SPECT images proved to be useful in the evaluation of abnormal perfusion areas of demented patients.

Cerebral blood flow (CBF) has been measured using a microsphere model with octanol-extracted radioactivity counts (integral value of input function). We developed a new method estimating the integral value of input function. First, we fitted the whole brain time-activity curves early after intravenous injection of N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) by the least-squares method. Second, we differentiated this equation. Third, we calibrated it using octanol-extracted radioactivity counts of the arterial blood sampled at 5 min. Finally, we integrated it. A significant correlation was found between the integral values obtained using a new method and those obtained using the continuous arterial blood sampling data (y = 1.048x-1206, r = 0.984). The errors between the CBF values obtained using a new method and those obtained using the 5-min continuous arterial blood sampling was 6.88 +/- 4.78%. Measurement of integral values of the input function using a new method with one-point arterial blood sampling is less invasive and convenient, and is not influenced by cardiopulmonary disease or smoking. Therefore, it would be useful for the routine measurement of CBF.