Localization of extratemporal epileptic foci during ictal single photon emission computed tomography.

We obtained single photon emission computed tomography (SPECT) scans with technetium-99M-hexamethyl-propylene-amine-oxime in 11 patients during 12 extratemporal partial seizures (9 simple partial, 3 complex partial). Ten ictal SPECT studies in 9 patients showed a focal region of hyperperfusion, which agreed with electrical seizure onset in 5 and with clinical seizure localization in 4 in whom ictal electroencephalography was not localized. Contralateral cerebellar and ipsilateral basal ganglia hyperperfusion was seen in 3 patients with a frontal lobe seizure focus. Ictal hyperperfusion was well circumscribed, unlike the diffuse hyperperfusion changes reported during temporal lobe seizures. This observation may indicate a different degree of seizure spread in temporal as opposed to extratemporal epilepsy. Because electroencephalographic localization is often elusive in extratemporal seizures, ictal SPECT may be very helpful for the localization of extratemporal foci.     

The diagnosis of dementia with single photon emission computed tomography

Single photon emission computed tomography is a practical modality for the study of physiologic cerebral activity in vivo. We utilized single photon emission computed tomography and N-isopropyl-p-iodoamphetamine iodine 123 to evaluate regional cerebral blood flow in nine patients with Alzheimer's disease (AD), five healthy elderly control subjects, and two patients with multi-infarct dementia. We found that all subjects with AD demonstrated flow deficits in temporoparietal cortex bilaterally, and that the ratio of activity in bilateral temporoparietal cortex to activity in the whole slice allowed the differentiation of all patients with AD from both the controls and from the patients with multi-infarct dementia. Furthermore, this ratio showed a strong correlation with disease severity in the AD group. Single photon emission computed tomography appears to be useful in the differential diagnosis of dementia and reflects clinical features of the disease.     

Opsoclonus-myoclonus syndrome with abnormal single photon emission computed tomography imaging

The single photon emission computed tomography (SPECT) findings in 2 patients with opsoclonus-myoclonus syndrome (OMS) who had similar symptoms in the acute stage of the disease are described. In 1 patient with encephalitis, SPECT showed increased blood flow in most of the cerebellum; the highest accumulation of the radiotracer was found in the cerebellar vermis and neighboring structures. These changes disappeared with clinical improvement. In the other patient with chronic OMS, SPECT demonstrated hypoperfusion in most of the cerebellum. Our results suggest that the cerebellum, particularly its middle portion, is involved in the generation of OMS. SPECT is a useful method that enables us to detect in vivo functional impairment in patients with OMS.     

Acute limbic encephalitis with focal hyperperfusion on single photon emission computed tomography

Here we report an 11-year-old boy with acute encephalopathy with neuropsychiatric symptoms. The patient had mildly decreased consciousness, delirious behavior, and affective changes next day of fever onset. Hematologic, biochemical, and metabolic examinations were unremarkable. CSF analysis revealed cell counts of 278 cells/mm³ and a protein level of 87 mg/dL. Although MRI revealed no abnormal findings, an increase in regional cerebral blood flow was present in the bilateral frontal lobes, mesial temporal lobes, and basal ganglia on single photon emission computed tomography. The measurement of the concentrations of biomarkers such as cytokines in the patient’s serum and cerebrospinal fluid revealed elevated levels of IL-4 and TNF-α in the cerebrospinal fluid. Immunohistochemical studies applying control human brain sections did not demonstrate the presence of autoantibodies. We considered that innate immunity rather than autoantibody response may have contributed to the neuropsychiatric symptoms of our patient. These results suggest heterogeneity of patients with acute encephalopathy with neuropsychiatric symptoms.     

Regional relationships between focal hypofixation images in 123I-IMP single photon emission computed tomography and epileptic EEG foci in interictal periods in patients with partial epilepsy.

Single photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123)-p-iodoamphetamine were performed in interictal periods in 40 patients with partial epilepsies and normal X-ray CT findings, and the regional relationships between the SPECT abnormalities and interictal epileptic EEG foci were studied. Twenty-six patients (65%) had abnormal SPECT images consisting of one or more focal hypofixation images, i.e., zones of decreased regional cerebral blood flow, while the remaining 14 patients showed normal images. Nineteen (73%) of the 26 patients showed complete or partial regional agreement between the abnormal SPECT findings and the interictal epileptic EEG foci determined from EEGs recorded repeatedly during their clinical course, while the regional relationships with the EEG foci determined from the single EEG recorded just after the SPECT scans or a short interval after the scans showed a lower rate of agreement (13 of 21 patients, 61.9%). These results confirm the utility of SPECT scans in the regional diagnosis of epileptic foci.     

抑郁症患者的脑单光子发射计算机断层摄影研究

为观察抑郁症患者局部脑血流（ｒＣＢＦ）情况，对１１例处于症状发作期的抑郁症患者及１３名正常对照者用９９ｍＴｃ标记的亚锡双半胱乙脂进行脑单光子发射电子计算机断层摄影（ＳＰＥＣＴ）。结果显示，观察组与对照组比较，左下额、左前颞及扣带皮质的ｒＣＢＦ显著下降（Ｐ＜０．０１），而右上额、右下额和两侧顶叶、枕叶的ｒＣＢＦ也有下降（Ｐ＜０．０５）。观察组尚存在上额皮质ｒＣＢＦ两侧非对称性（Ｐ＜０．０５），而对照组未见相应的非对称性。提示抑郁症发作时存在某些脑功能区ｒＣＢＦ下降以及两侧脑功能区局部的ｒＣＢＦ不对称性。     

Early single photon emission computed tomography in Sturge-Weber syndrome

OBJECTIVES—Functional cerebral imaging PET and SPECT have shown hypometabolism and hypoperfusion in the area of vascular malformation in children with epilepsy due to Sturge-Weber syndrome. However, data are scarce in infants and do not exist in patients with Sturge-Weber disease without epilepsy. The pattern of perfusion during the first two years of life was studied including patients before the onset of seizures.
METHODS—Twenty two infants with later confirmed Sturge-Weber disease underwent SPECT examination using TOMOMATIC 564 (Medimatic) and xenon-133 at ages ranging from 8 days to 25 months. Twelve had never had seizures before SPECT and seven underwent a second SPECT a mean seven months later. Cerebral blood flow (CBF) was measured in the whole hemisphere and in the part of the cortex involved in the vascular malformation on both sides as well as a ″pathological to normal″ index for the hemisphere and vascular malformation. These values were compared with normal age paired values.
RESULTS—Compared with controls, CBF and the indices in the hemisphere and vascular malformation were significantly decreased in patients who already had had seizures before SPECT, whereas they were significantly increased in 75% of the patients who had never had any seizures. On second SPECT, the indices were decreased in all patients, including the four who still remained non-epileptic.
CONCLUSIONS—SPECT therefore detects CBF asymmetry in infants with Sturge-Weber disease, which tends to shift with age. The cortex involved in the vascular malformation is hyperperfused during the first year of life before first seizures. The classic hypoperfusion appears after one year of age, even in non-epileptic patients.

     

Brain single photon emission computed tomography (SPECT) in neuropediatrics

The clinical value in neuropediatrics of [99mTc]HM-PAO brain single photon emission computed tomography was preliminary evaluated by the consecutive investigation of 79 children. Planned epilepsy surgery was the most common indication for the investigation. In 56 children investigated because of epilepsy, SPECT yielded relevant information in 79% of cases examined. The corresponding figures for magnetic resonance imaging and CT were 49% of 35 and 36% of 56 cases, respectively. All 22 children with an epileptic focus, ascertained by freedom from seizures after removal of the area or by consistent neurophysiological and neuroradiological findings, also had abnormal perfusion in the relevant area. Twenty-three children were examined because of neurological signs and symptoms other than epilepsy. SPECT findings were useful for elucidating neonatal brain impairments. Hypoperfused areas in the brain of asphyxiated infants and in posthemorrhagic hydrocephalus corresponded to neuroradiological and autopsy findings. SPECT was found to be an excellent tool when analysing cerebrovascular accidents. In cases with signs and symptoms of a diffuse severe encephalopathy, SPECT did not clarify the etiology but provided information on the distribution of the lesions and probable underlying pathophysiological mechanisms.     

99mTc-HMPAO single photon emission computed tomography (SPECT) in both asphyxiated and epileptic children with or without status epilepticus

In this study, technetium 99m hexamethylpropyleneamine oxime (99mTc-HMPAO) single photon emission computed tomography (SPECT) was performed on 18 asphyxiated and epileptic children who also had a status epilepticus episode, and the results were compared with those for 21 children without a status epilepticus episode. All patients underwent a detailed neurologic history, interictal electroencephalography, computed tomography, and/or magnetic resonance imaging. Visual evaluation of the SPECT study showed that 16 patients of group 1 had 56 hypoperfused regions in cerebral blood flow. However, in group 2, visual evaluation showed only six detectable hypoperfusion areas in five patients. When an asymmetric index value of 3 was considered as a cutoff point, 82 regions in group 1 and 57 regions in group 2 were above this value after the quantitative SPECT evaluation. The mean number of pathologic brain regions was found to be higher in group 1 (5.1 +/- 4.3) than in group 2 (2.7 +/- 2.4) (P = .014). The localization of hypoperfused regions that were observed in temporal and frontal regions was generally similar in both groups. In conclusion, the functional activities of the brain vary in both asphyctic and epileptic children, with and without status epilepticus. These children might be candidates for refractory convulsive disease, and interictal SPECT can be a reliable method for the detection of brain lesions in these patients.     

The current place of single photon emission computed tomography in epilepsy evaluations

Single photon emission computed tomography is appropriate for peri-ictal imaging inpatients with focal epilepsy being considered for surgical treatment.     

Positron emission tomography in presurgical localization of epileptic foci

The success of cortical resection for intractable epilepsy of neocortical origin is highly dependent on the accurate presurgical delineation of the regions responsible for generating seizures. In addition to EEG and structural imaging studies, functional neuroimaging such as positron emission tomography (PET) can assist lateralization and localization of epileptogenic cortical areas. In the presented studies, objectively delineated focal PET abnormalities have been analyzed in patients (mostly children) with intractable epilepsy, using two different tracers: 2-deoxy-2-[18F]fluoro-D-glucose (FDG), that measures regional brain glucose metabolism, and [11C]flumazenil (FMZ), that binds to GABAA receptors. The PET abnormalities were correlated with scalp and intracranial EEG findings, structural brain abnormalities, as well as surgical outcome data. In patients with extratemporal foci and no lesion on MRI, FMZ PET was more sensitive than FDG PET for identification of the seizure onset zone defined by intracranial EEG monitoring. In contrast, seizures commonly originated from the border of hypometabolic cortex detected by FDG PET suggesting that such areas are most likely epileptogenic, and should be addressed if subdural EEG is applied to delineate epileptic cortex. In patients with cortical lesions, perilesional cortex with decreased FMZ binding was significantly smaller than corresponding areas of glucose hypometabolism, and correlated well with spiking cortex. Extent of perilesional hypometabolism, on the other hand, showed a correlation with the life-time number of seizures suggesting a seizure-related progression of brain dysfunction. FMZ PET proved to be also very sensitive for detection of dual pathology (coexistence of an epileptogenic cortical lesion and hippocampal sclerosis). This has a major clinical importance since resection of both the cortical lesion and the atrophic hippocampus is required to achieve optimal surgical results. Finally, the author demonstrated that in patients with neocortical epilepsy, FDG PET abnormalities correctly regionalize the epileptogenic area, but their size is not related to the extent of epileptogenic tissue to be removed. In contrast, complete resection of cortex with decreased FMZ binding predicts good surgical outcome suggesting that application of FMZ PET can improve surgical results in selected patients with intractable epilepsy of neocortical origin.     

Brain perfusion single photon emission computed tomography in children after acute encephalopathy

We studied single photon emission computed tomography (SPECT) of 15 children with acute encephalopathy after more than 1 year from the onset, using technetium-99 m-L, L-ethyl cystinate dimer (99mTc-ECD) and a three-dementional stereotaxic region of interest template. Regional cerebral blood flow was evaluated and divided in three groups according to the severity of disability: absent or mild, moderate, and severe. There was no abnormality on SPECT in the patients without disability or with mild disability. Diffuse hypoperfusion was shown in the groups with moderate and severe disability. The patients with severe disability showed hypoperfusion in the pericallosal, frontal and central areas which was more pronounced than in the patients with moderate disability.     

Hot water epilepsy: Phenotype and single photon emission computed tomography observations

We studied the anatomical correlates of reflex hot water epilepsy (HWE) using multimodality investigations viz. magnetic resonance imaging (MRI), electroencephalography (EEG), and single photon emission computed tomography (SPECT). Five men (mean age: 27.0 ΁ 5.8 years) with HWE were subjected to MRI of brain, video-EEG studies, and SPECT scan. These were correlated with phenotypic presentations. Seizures could be precipitated in three patients with pouring of hot water over the head and semiology of seizures was suggestive of temporal lobe epilepsy. Ictal SPECT showed hyperperfusion in: left medial temporal — one, left lateral temporal — one, and right parietal — one. Interictal SPECT was normal in all five patients and did not help in localization. MRI and interictal EEG was normal in all the patients. The clinical and SPECT studies suggested temporal lobe as the seizure onset zone in some of the patients with HWE.     

Brain single photon emission computed tomography: technological aspects and clinical applications

Single photon emission computed tomography (SPECT) is obtained by the injection of one of a series of compounds that cross the blood-brain barrier and are distributed in the brain according to regional perfusion or to the density of a given receptor. The regional brain distribution of the injected compound can be measured because it is bound to a radioactive substance that emits photons. Emitted photons are collimated to facilitate determining their source and detected with sodium iodine crystal detectors. Finally, the techniques of CT are used to reconstruct the density of photons emitted by each volume element (voxel) of the brain. Less expensive and more widely distributed in nuclear medicine departments than positron emission tomography, SPECT is currently used mainly in the evaluation for epilepsy surgery, of cerebrovascular disease, and of the parkinsonian and other neurodegenerative syndromes. In this article, we discuss the technological aspects of brain SPECT and its clinical neurological applications.     

Ictal single photon emission computed tomography in seizures induced by eye closure

Ictal single photon emission computer tomography (SPECT) studies were performed on a 12 year old child with reflex seizures induced by eye closure. EEGs had shown generalised polyspike waves during eye closure. A magnetic resonance head scan was normal. There was no photosensitive induction of the seizure. Comparison between ideal and post treatment (ethosuximide) interictal SPECT revealed increased ictal perfusion in the basal ganglis, lateral frontal region and superior temporal lobe in the left hemisphere. It is suggested that the reflex epilepsy in this case was triggered by sensory afferents from the orbicularis oculi and mediated via the thalamus.     

Brain blood flow studies with single photon emission computed tomography in patients with plateau waves

The authors studied brain blood flow with single photon emission computed tomography (SPECT) in two patients with plateau waves. The intracranial pressure and blood pressure were also monitored continuously in these patients. They included one patient with brain-tumor (rt. sphenoid ridge meningioma) and another with hydrocephalus after subarachnoid hemorrhage due to rupture of lt. internal carotid aneurysm. The intracranial pressure was monitored through an indwelling ventricular catheter attached to a pressure transducer. The blood pressure was recorded through an intraarterial catheter placed in the dorsalis pedis artery. Brain blood flow was studied with Headtome SET-011 (manufactured by Shimazu Co., Ltd.). For this flow measurement study, an intravenous injection of Xenon-133 of about 30 mCi was given via an antecubital vein. The position of the slice for the SPECT was selected so as to obtain information not only from the cerebral hemisphere but also from the brain stem: a cross section 25 degrees over the orbito-meatal line, passing through the inferior aspect of the frontal horn, the basal ganglia, the lower recessus of the third ventricle and the brain stem. The results indicated that, in the cerebral hemisphere, plateau waves were accompanied by a decrease in blood flow, whereas, in the brain stem, the blood flow showed little change during plateau waves as compared with the interval phase between two plateau waves. These observations may explain why there is no rise in the blood pressure and why patients are often alert during plateau waves.     

A case of multiple sclerosis with abnormal single photon emission computed tomography (SPECT)]

A case of a 38-year-old woman with multiple sclerosis (MS) is reported. At 36 years of the age, she was admitted to our hospital because of developing unstable gait and clumsiness in her hands. After intravenous and oral administration of steroid, her neurological symptoms improved gradually. At 38 years of the age, she was readmitted because of recurrence. A neurological examination revealed severe left sided limb ataxia and trunkal ataxia. No abnormal finding was demonstrated in cranial MRI at the first and second admission. Single photon emission computed tomography (SPECT) using 123I-IMP that was performed at the second admission showed an increased accumulation of 123I-IMP in the left cerebellar hemisphere on the 14th day from the neurological onset. After the therapy of steroid, her neurological signs improved and SPECT showed no abnormality on the 62nd day. Seven months after the second episode, she was readmitted because of the same neurological symptoms and T2 weighted MRI revealed multiple high intensity area in the pons and midbrain. She was diagnosed as having definite MS. These findings in SPECT may suggest the inflammatory process of the cerebellum in the case of MS as well as acute cerebellar ataxia.     

Quantitative assessment of cerebral hemodynamics using single photon emission computed tomography with venous blood sampling

Objective

Quantitative cerebral blood flow (CBF) measured by single photon emission computed tomography (SPECT) with arterial blood sampling is one of the most reliable methods to assess the hemodynamics in individual patients. SPECT with venous blood sampling is less invasive. The present study compared the measurement of CBF using N-isopropyl-p-(iodine-123)-iodoamphetamine SPECT with venous blood sampling and with arterial blood sampling in patients with major cerebral artery occlusive disease.

Methods

Two normal subjects and 14 patients with major cerebral artery occlusive disease underwent SPECT with arterial and venous blood sampling. The microsphere method was used for quantitative SPECT imaging. Whole brain radioactivity was corrected when the detectors rotated in the forward direction (F₁–F₇). Venous sampling was performed 30 min after radiotracer injection. Arterial blood radioactivity was estimated by multiple regression analysis from these parameters. The cerebrovascular reactivity to acetazolamide was also measured.

Results

Multiple regression analysis established the following formula:

Ca₁₀=−1.099F₁+1.629F₂−2.143F₃−2.766F₄−1.208F₅+2.113F₆+3.259F₇+1.241Cv₃₀+94.958${\text{Ca}}_{10}=-1.099{\text{F}}_1+1.629{\text{F}}_2-2.143{\text{F}}_3-2.766{\text{F}}_4-1.208{\text{F}}_5+2.113{\text{F}}_6+3.259{\text{F}}_7+1.241{\text{Cv}}_{30}+94.958$     

The EEG evaluation of single photon emission computed tomography abnormalities in epilepsy.

Single photon emission computed tomography (SPECT) has increasingly been used as a diagnostic procedure for localizing epileptic seizure foci and as a research tool for investigating the physiologic mechanisms underlying seizure activity. With increasing use of SPECT in localizing the seizure focus for epilepsy surgery, there arises a need to critically assess its current role in the evaluation of patients for epilepsy surgery, especially as it relates to other clinical and laboratory data used in presurgical evaluation. Ictal EEG discharge has traditionally been used as the "gold standard" against which SPECT studies are compared in assessing the latter's localizing value. However, this practice presents a major challenge because SPECT studies are often reserved for patients with nonlocalizing EEG or magnetic resonance imaging findings. Nonetheless, SPECT studies in evaluation for epilepsy surgery should always be performed with the knowledge of the patient's EEG activity preceding, during, and after the injection of the radiotracer. The advent of techniques such as subtraction SPECT with co-registration on magnetic resonance imaging (SISCOM) and computer image-guided surgery has great potential in enhancing the clinical electrophysiologic evaluation of SPECT-detected abnormalities in epilepsy. These techniques permit accurate spatial correlation between intracranial EEG activity and SPECT perfusion patterns. The techniques can also be used to evaluate the effect of the extent of EEG focus resection compared with that of SISCOM focus resection to determine which has more prognostic importance in postsurgical control of seizures. Both animal and human studies are warranted to advance our knowledge of the electrophysiology associated with the various SPECT perfusion patterns.