99mTc-HMPAO labeled leukocyte SPECT in intracranial lesions

BACKGROUND: Scintigraphy with 111In (indium-111)-oxine or 99mTechnetium-hexamethylpropyleneamine oxime (99mTc-HMPAO) labeled leukocytes has been used to differentiate brain abscess from brain tumor. However, there are false positive or false negative results from planar scintigraphic images. So a more specific and sensitive scintigraphic technique needs to be developed. METHODS: Planar and single photon emission computed tomography (SPECT) images were obtained and reviewed in 14 patients with intracerebral ring-enhancing lesions on computed tomography (CT) or magnetic resonance imaging (MRI). In all patients, diagnosis was confirmed by histopathologic examination. The effect of steroids or antibiotics on scintigraphic finding was examined. RESULTS: Abscess was confirmed in six patients, tumor in six, tuberculoma and cysticercosis in one each, respectively. In all the patients with abscess, SPECT showed increased focal activity irrespective of steroid or antibiotic therapy. Increased radioactivity, which could not be detected on planar images, could be identified in two patients with abscess. In three of the six patients with tumor, radiolabeled leukocytes did not accumulate in the tumor. In the other three patients with tumor, SPECT showed focally increased activity that was less intense than the activity shown in the patients with abscess. CONCLUSIONS: 99mTc-HMPAO labeled leukocyte SPECT is useful for the differential diagnosis of intracerebral ring-enhancing lesions, and the use of steroids or antibiotics does not influence the sensitivity of SPECT. Diagnostic sensitivity of scintigraphy with labeled leukocytes could be improved by SPECT in addition to planar image.     

Olfactory-evoked regional cerebral blood flow in Alzheimer's disease.

Olfaction is impaired in Alzheimer's disease (AD). It was hypothesized that AD would reduce olfactory-evoked perfusion in mesial temporal olfactory (piriform) cortex, where neuropathology begins. Seven AD patients and 8 elderly controls (ECs) underwent olfactory threshold and identification tests and olfactory stimulation during positron emission tomography. Odor identification was impaired in AD, but threshold was not. Olfactory stimulation in ECs activated right and left piriform areas and right anterior ventral temporal cortex. AD patients had less activation in right piriform and anterior ventral temporal cortex but not in the left piriform area. Although orbital cortex did not activate in ECs, there was a significant between-groups difference in this area. Right piriform activation correlated with odor identification. Impaired odor identification likely reflects sensory cortex dysfunction rather than cognitive impairment. Given olfactory bulb projections to the mesial temporal lobe, olfactory stimulation during functional imaging might detect early dysfunction in this region. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantification of cerebral blood flow with 99mTc-ECD SPECT by a single arterial or venous blood sample

The purpose of the study is to develop a simple and less invasive method for quantifying regional cerebral blood flow (rCBF) using 99mTc-ECD and SPECT. By employing a microsphere model, a new method to measure rCBF was developed, which required a single arterial or venous sample instead of continuous withdrawal of arterial blood. Using a regression line, the integral of input function of arterial blood from 0 to 30 min was inferred by activity of arterial blood sampled at time t; A(t), by activity multiplied by its octanol extraction rate; AN(t), by activity of venous blood at time t; V(t), and by activity multiplied by its octanol extraction rate; VN(t). The optimum sampling time of arterial or venous blood was examined when mean % error for inference became minimum. Consequently, minimum error of AN(6 min) was 5.5%, A(3 min) was 8.9%, VN(6 min) was 5.9%, and V(20 min) was 10.0%. Quantitative measurement of rCBF using the value of VN(6 min) was performed on other 6 subjects with dementia etc. To validate the method, 133Xe inhalation SPECT studies were also performed on the same subjects. We found a good agreement between them (r = 0.851). The presented one-point sampling methods were simple and less invasive for quantifying rCBF.     

Relations between neuropsychological findings and lateral asymmetries of cerebral blood flow measured by SPECT in dementia of Alzheimer type

We studied 16 right-handed patients clinically diagnosed as dementia of Alzheimer type (6 men, 10 women; aged 63-85, mean 72.8 years). The average duration of symptoms was 2.7 years. Dementia ranged from mild to moderately severe. None had clinical or laboratory evidence of cerebrovascular disease (Hachinski ischemic scores for all patients were 4 or below 4). All received the Wechsler Adult Intelligence Scale (WAIS), Mini-mental State Test (MMS) and Western Aphasia Battery (WAB, First Japanese edition, 1986). Regional cerebral blood flow (rCBF) was evaluated by single photon emission CT (SPECT) with 123I-N-isopropyl-p-iodoamphetamine (123I-IMP), using the Matsuda's quantitative method (Am J Physiol Imag 1: 186, 1986). Regional tracer uptake was measured in regions of interests (ROIs) over right and left frontal, temporal, parietal and occipital cortical regions; basal ganglia; and cerebellar hemispheres. The subjects were divided into three groups on the basis of lateral asymmetries in the temporal and parietal cortexes of rCBF (left < right, n = 5; right < left, n = 3; left = right, n = 8). We decided that lateral asymmetry was present when rCBF for each ROI between left and right sides differs by more than 10%. General score (MMS, T-IQ) was not correlated with asymmetry of cerebral blood flow. Verbal IQ in patients with predominant hypoperfusion of left temporal and parietal lobe was significantly lower than other group, while performance IQ and WAB constructive scores were lower in those with right hemispheric hypoperfusion (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Quantification of cerebral blood flow with 99mTc-ECD SPECT based on a 3-compartment model

In the present study we developed a method for quantifying regional cerebral blood flow (rCBF) using 99mTc-ECD SPECT based on a 3-compartment model. The dynamic SPECT scanning and sequential sampling of arterial blood were performed on 12 subjects with cerebrovascular diseases and etc. We defined brain fractionation index (BFI) as a parameter of rCBF, which was obtained from a single SPECT data and arterial input. The relationship between the values of BFI and rCBF obtained by the 133Xe inhalation method was analyzed by approximation with exponential function. In this method, rCBF was calculated from the values of BFI using the inverse function of the exponential function as a regression curve. The method was applied seven other patients with cerebrovascular diseases and the values of rCBF were compared with those obtained by the 133Xe inhalation method. We observed a good correlation (r = 0.854), and the inclination was approximately 1. This method can be applied to not only large field SPECT cameras but also conventional SPECT cameras.     

A comparative cerebral blood flow study in a baboon model with acetazolamide provocation: 99mTc-HMPAO vs 123I(IMP)

Pharmacological interactions are important when nuclear medical procedures are applied to patients under drug therapy, or drug provocation. This study compares in baboon models (regional) cerebral blood flow [(r)CBF] results from 99mTc-HMPAO and 123I-iodoamphetamine [123I(IMP)] each with and without acetazolamide, the latter a suggested drug for testing cerebrovascular reserve. Expected differences in cerebral uptake were observed between the two radio-tracers without acetazolamide. The increase in tracer uptake resulting from acetazolamide is significantly enhanced for 123I(IMP), which could have diagnostic implications.     

Assessment of brain perfusion by 99mTc-HMPAO SPECT in akinetic mutism due to high-dose intravenous methotrexate therapy

Chemotherapy of the central nervous system may cause neurotoxicity in children with acute lymphocytic leukemia. We evaluated regional blood flow in a 6-year-old child presenting with akinetic mutism, using 99mTc-HMPAO single photon emission tomography (SPECT) following high-dose intravenous methotrexate therapy. While findings in X-ray computerized tomography were decreased density in bilateral basal ganglia and thalamic nuclei with diffusely decreased attenuation of the periventricular white matter, a global, frontal dominant profoundly abnormal perfusion pattern involving both gray and white matter was observed in the SPECT study. Treatment of the central nervous system with high dose intravenous chemotherapy may cause profound abnormalities in white and gray matter blood flow and early assessment of the neurotoxicity may be identified by 99mTc-HMPAO SPECT in the pediatric age group.     

Regional cerebral blood flow in focal cortical epilepsy

Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were studied both during a seizure and (in the same setting) in the interictal period; six patients were studied only in the interictal period, and one patient was studied only during a seizure. Studies during seizures all showed marked flow increases in areas presumed to participate in the seizure activity. This finding accords with earlier studies. All nine patients studied in the interictal phase showed, either spontaneously or during activation by intermittent light, focal flow increases in areas presumed to comprise the epileptic focus. These interictal hyperemic foci probably reflect subictal neuronal hyperactivity in epileptogenic nervous tissue. Only two of the patients had distinct epileptic electroencephalographic foci. It appears that rCBF studies can be a valuable diagnostic tool in the investigation of cortical epileptogenic lesions.     

Regional cerebral blood flow in pediatric moyamoya disease: age-dependent decline in specific regions

Thirteen pediatric patients (ages 4-13 years) who underwent surgical treatment were examined regarding their rCBF in the preoperative periods. The postoperative rCBF was measured 39 times in these 13 patients. Thirteen healthy normal subjects (ages from 6 to 21 years) were also examined. The rCBF in the operculum and in the frontal, parietal, and occipital lobes was measured with 133Xe inhalation method and single photon emission computed tomography. In the parietal and occipital lobes, the preoperative rCBF had a negative and significant correlation with their ages, but not in the operculum or frontal lobe. However, subsequent to the surgical treatment, the rCBF increased significantly in the patients 5 years old or less, and then post-operative rCBF values had significant negative correlations with age in each region.     

Regional cerebral glucose metabolism and postmortem pathology in Alzheimer's disease

In four patients with an antemortem diagnosis of probable Alzheimer's disease (AD) regional cerebral glucose metabolism (rCMRGl) was studied prospectively by positron emission tomography (PET) and compared with postmortem semiquantitative neuropathology. The interval between the last PET study and autopsy was 1.3 +/- 0.8 years. In comparison with age-matched controls, the AD patients showed predominant temporoparietal hypometabolism spreading to other cortical and subcortical regions during serial PET scans. All patients had neuropathological findings typical for AD. There was a significant relationship between rCMRGl and density of senile plaques (SP) in one patient (tau b = -0.86, P < 0.05). SP were distributed quite homogeneously in all regions examined. Neurofibrillary tangles (NFT) were concentrated focally in the hippocampus-amygdala-entorhinal complex. In the context of widespread developing cortical hypometabolism, the predilection of NFT for involvement in limbic areas suggests a disruption of projection neurons as the pathogenetic process of cortical dysfunction.     

99mTc-HMPAO brain SPECT imaging in a case of repeated syncopal episodes associated with smoking

BACKGROUND: We report here a rare case of repeated syncopal episodes associated with smoking and findings of 99mTc-hexamethylpropyleneamine oxime (HMPAO) brain single-photon emission CT (SPECT) imaging. CASE DESCRIPTION: A 77-year-old man had four syncopal episodes during a half-month period. All four occurred when he stood up and walked immediately after smoking a cigarette, and syncope did not occur after cessation of smoking. Although upright testing revealed orthostatic hypotension, the patient did not complain of fainting on standing alone. Compared with brain SPECT in the supine position, perfusion was decreased in the posterior circulation structures after the subject smoked a cigarette or chewed nicotine gum. CONCLUSIONS: The combination of cerebral vasoconstriction due to smoking and orthostatic hypotension probably decreased cerebral blood flow in this patient, resulting in syncope.     

Neuropsychological, psychiatric, and cerebral blood flow findings in vascular dementia and Alzheimer's disease

BACKGROUND AND PURPOSE: Psychiatric, neuropsychological, and cerebral blood flow differences between patients with ischemic vascular dementia (IVD) or Alzheimer's disease (AD) were examined. METHODS: A consecutive series of patients who met either the criteria of the National Institute of Neurological Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association for probable AD or the State of California AD Diagnostic and Treatment Centers criteria for probable IVD were included in the study. Twenty consecutive patients with IVD were matched for age, sex, and Mini-Mental State Examination scores with 40 consecutive patients with probable AD. Patients underwent a psychiatric interview, a neuropsychological assessment, and single-photon emission CT imaging with 99mTc-hexamethylpropyleneamine oxime. RESULTS: Patients with IVD showed significantly more severe anosognosia (P<.05) and emotional lability (P<.01) than AD patients, but no significant between-group differences were found in the frequency and severity of depression. IVD patients showed significantly more severe deficits in tests of planning, sequencing (P<.05), and verbal fluency (P<.05) as well as significantly more severe cerebral blood flow deficits in the basal ganglia (P<.01) and the frontal lobes (P<.001) than AD patients. CONCLUSIONS: Patients with IVD showed a relatively more severe dysfunction of the frontal lobes as demonstrated by single-photon emission CT and expressed in specific psychiatric and neuropsychological changes than AD patients matched for age, sex, and severity of dementia.     

Regional cerebral blood flow during experimental phobic fear

Positron emission tomographic measurements of regional cerebral blood flow (rCBF) were used to investigate central nervous system correlates of fear and anxiety. Volunteers with symptomatic snake phobia were studied while exposed to visual phobogenic, aversive, and neutral stimuli. Anxiety ratings and the number of nonspecific electrodermal fluctuations increased as a function of phobic stimulation. Phobic, compared to neutral and aversive, stimulation elevated rCBF in the visual associative cortex. The basal ganglia were not activated more by phobic than aversive or neutral stimulation. However, cortical and thalamic rCBF were always correlated during phobic but not aversive or neutral stimulation. This indicates that the thalamus could be a relay station for phobic stimulus processing and affect.     

Regional differences of cerebral blood flow in the preterm infant

The purpose of our study was to evaluate the regional distribution of the resting cerebral blood flow (CBF) pattern in preterm neonates. Sixty-eight preterm babies with a gestational age of less than 34 weeks and a birth weight of less than 1500 g were enrolled into the study. The CBF was measured by the noninvasive intravenous 133Xenon method at three different times. Depending on the age we classified our measurements into three groups. Group 1: measurement between 2-36 h (n = 46). Group 2: measurement between 36-108 h (n = 39). Group 3: measurement between 108-240 h (n = 41). In all three groups CBF was significantly lower in the occipital region than in the frontal and parietal regions (group 1: frontal region 12.8 +/- 3.5 ml/100 g/min, parietal region 12.8 +/- 3.9 ml/100 mg/min, and occipital region 11.6 +/- 3.18 ml/100 g/min; group 2: frontal region 15.4 +/- 4.2 ml/100 g/min, parietal region 15.3 +/- 4.1 ml/100 g/min, and occipital region 13.4 +/- 3.5 ml/100 g/min; group 3: frontal region 14.6 +/- 3.6 ml/100 g/min, parietal region 14.6 +/- 3.2 ml/100 g/min, and occipital region 12.8 +/- 2.7 ml/100 g/min.). CBF did not differ between the left and the right hemispheres in either of the three measured regions. No gradient was found in infants between 108 h and 240 h of age with periventricular leukomalacia and periventricular haemorrhage. CONCLUSION. In preterm neonates the antero-posterior gradient of CBF is already present. Periventricular leukomalacia as well as periventricular haemorrhage may affect the regional regulation of CBF.     

Effect of kanji and kana reading on cerebral blood flow patterns measured by PET

To investigate the respective functions of pathways in processing visual information from different types of symbols, by positron emission tomography (PET) we examined the effect on cerebral blood flow (CBF) of reading the Japanese morphogram (kanji) versus the syllabogram (kana). Nine Japanese men were presented with three visual conditions in random order 2 minutes before the scan: eyes open controls, kanji morphogram reading, and kana syllabogram reading. Three words written in kanji or kana were shown, and subjects were instructed to read them silently and to identify the word unrelated logically to the other two. The reading and analyzing tasks activated wide areas of vision-related cortices. The comparison of the kanji and kana readings showed higher metabolism, with the former only in the posterior part of the primary visual cortex. Most of the CBF increases were common for both stimuli, although the patterns of these increases differed slightly. The correlation matrix of CBF change in the left hemisphere showed a ventral connection in kanji reading and a dorsal connection in kana reading. Our results suggest there is a functional differentiation in the brain between patterned and sequential perception when reading Japanese morphograms and syllabograms.     

Chronic schizophrenia: validity of the study of regional cerebral blood flow through cerebral SPECT

OBJECTIVE: To check the validity of the diagnostic test in schizophrenia. MATERIAL AND METHODS: The cerebral blood flow (CBF) characteristics were assessed by means of single photon emission tomography (SPECT) in 24 patients with schizophrenia and 20 normal control subjects. Analysis of sensitivity, specificity and the Youden rate was made of certain RCBF patterns chosen in terms of the cerebral regions between which the greatest differences were observed according to the diagnosis, schizophrenia vs control. RESULTS: Schizophrenia vs control: sensitivity = 58.33%; specificity = 95%; positive predictive value = 93.33% and overall efficiency = 53.33%. CONCLUSIONS: Cerebral SPECT is valid in the discrimination between patients diagnosed with schizophrenia and control subjects, taking the diagnostic judgement of the psychiatrist as the gold standard, and the RCBF pattern that displays the best coefficient is hypoperfusion, in one or several of the regions: right frontal/left frontal/right parietal/thalamus: sensitivity = 58.33%; specificity = 95%; positive predictive value = 93.33% and overall efficiency = 53.33%.     

Cerebral blood flow measurement in patients with impaired consciousness: usefulness of 99mTc-HMPAO single-photon emission tomography in clinical practice

The relationship between impairment of consciousness and quantitative cerebral blood flow (CBF) was investigated. The mean CBF of the whole brain was measured by the Patlak-plot method using technetium-99m hexamethylpropylene amine oxime single-photon emission tomography (99mTc-HMPAO SPET) in patients with the following diseases: cerebral infarction, intraparenchymal haemorrhage, subarachnoid haemorrhage, brain tumour and cerebral contusion. The clinical symptoms were evaluated according to the severity of impaired consciousness, aphasia and dementia. Four hundred and eighty-five CBF measurements were performed. Patients with alert consciousness showed an age-related decline in mean CBF. Patients with aphasia showed a significant reduction in mean CBF compared with those without aphasia. Impaired consciousness was proportional to reduction in mean CBF regardless of types of pathology, and the size of lesion did not influence the mean CBF. Patients with dementia showed a significant reduction in mean CBF proportional to the severity of dementia. The quantitative measurement of CBF using 99mTc-HMPAO SPET is reliable in clinical evaluations.     

Quantitative measurement of cerebral blood flow by the microsphere model with super-early 123I-IMP brain SPECT

Cerebral blood flow (CBF) was quantitatively measured in 6 healthy young volunteers based on "super-early" acquisition of N-isopropyl-p-[123I]iodoamphetamine (IMP) brain SPECT obtained 4-6 min after IMP injection with a three-head rotating gamma camera and the microsphere (MS) model. The ratio of radioactivity (count/pixel/min) in the conventional early SPECT image (taken 25-55 min after IMP injection) to that in the "super-early" image for each brain region negatively correlated with regional CBF value obtained with the "super-early" MS method. This indicates that wash-out of IMP from the regions with higher CBF is faster than that from the regions with lower CBF and that CBF values are underestimated with the conventional MS method in regions with higher CBF. Regional CBF was quantitatively measured with the "super-early" MS method and the ARG method, a recently developed method based on two-compartment model. The mean cortical CBF was 52.5 +/- 7.0 (ml/100 g/min, mean +/- SD) with the "super-early" MS method and 47.5 +/- 3.3 with the ARG method. The CBF values obtained with the "super-early" MS method agreed with those previously reported with positron emission tomography. Since the MS method is theoretically the simplest model, the "super-early" MS method can be applied various disorders of the central nervous system where the behavior of IMP is not fully understood.