Comparison of statistical parametric mapping and SPECT difference imaging in patients with temporal lobe epilepsy

PURPOSE: Statistical parametric mapping (SPM) is an image-analysis tool that assesses the statistical significance of cerebral blood flow (CBF) changes on a voxel-by-voxel basis, thereby removing the subjectivity inherent in conventional region-of-interest (ROI) analysis. Our platform of single-photon emission computed tomography (SPECT) ictal-interictal difference imaging in clinical epilepsy has been validated for localizing seizure onset. We extend the tools of SPM by further applying statistical measures for the significance of perfusion changes in individual patients to localize epileptogenic foci in patients with defined temporal lobe epilepsy by using paired scans in this preliminary study. METHODS: Twelve patients with pairs of periictal and interictal SPECT scans were analyzed in this comparison study between SPECT difference imaging and SPM difference analysis by using a reference database of paired normal healthy images. These 12 patients possessed seizure foci localized to the mesial temporal lobe as confirmed by surgical outcome and by hippocampal sclerosis on pathology. SPM was used to identify clusters of increased or decreased CBF in each patient in contrast to our control group. RESULTS: The regions having the most significant increased or decreased CBF by SPM analysis were in agreement with regions identified by conventional difference imaging and visual analysis by viewers blinded to the results of the SPM analysis. Differentiated further by time of radiopharmaceutical injection, six of seven patients injected within 100 s of seizure onset displayed hyperperfusion changes localized to the corresponding epileptogenic temporal lobe by both techniques. Among patients receiving injections after 100 s, both techniques showed primarily regions of hypoperfusion, which again were similar between these two methods. CONCLUSIONS: The results provide strong evidence supporting SPM difference analysis in assessing regions of significant CBF change from baseline in concordance with our current clinically used technique of SPECT ictal--interictal difference imaging in epilepsy patients. Difference analysis using SPM could serve as a useful diagnostic tool in the evaluation of seizure focus in temporal lobe epilepsy.     

SPECT and epilepsy with continuous spike waves during slow-wave sleep

Ten cases of epilepsy with continuous spike waves in slow-wave sleep (CSWS) were evaluated using single photon emission computed tomography (SPECT); in eight patients the EEG paroxysmal abnormalities showed a predominant localization. SPECT carried out using^99mTc-HMPAO allows study of cerebral blood flow (CBF); the examination was performed during phases of drowsiness and the results compared to the EEG data. In four cases SPECT revealed areas of low CBF in sites corresponding to those of the prevalent EEG discharges; in two cases the areas of hypoperfusion did not correspond to those indicated by the EEG; lastly, in four cases SPECT results were negative. The areas of hypoperfusion were predominantly located in the frontal, temporal, and parietal regions. Furthermore, the percentage of positive SPECT results was significantly higher (five cases out of six) in the group in which the CSWS phase was prolonged for at least 1 year, compared to the group in which this phase lasted less than 1 year. Thus, in this type of epilepsy, SPECT reveals focal cortical areas of decreased CBF which correlated generally to the predominant sites of EEG abnormalities. A longer duration of the CSWS phase seems to be associated with a more significant cortical disorder, documented by the presence of areas of hypoperfusion.     

Ictal hyperperfusion patterns in relation to ictal scalp EEG patterns in patients with unilateral hippocampal sclerosis: a SPECT study

PURPOSE: The aims of the present study were to explore the relation between ictal scalp EEG patterns and ictal hyperperfusion patterns in patients with unilateral hippocampal sclerosis-associated mesial temporal lobe epilepsy (HS-MTLE) by using semiquantitative single-photon emission computed tomography (SPECT) analysis and to assess clinical significance of ictal hyperperfusion patterns. METHODS: We studied retrospectively 39 consecutive patients with surgically proven HS-MTLE. All had both interictal and ictal SPECTs with the tracer injection during a complex partial seizure (CPS) typical of MTLE semiology. According to initial ictal discharge (IID) frequency on scalp EEG, two lateralizing patterns were identified: (a) a sustained regular 5- to 9-Hz rhythm with a restricted temporal or subtemporal distribution (group 1); and (b) an irregular 2- to 5-Hz rhythm with a widespread distribution (group 2). We performed group analysis by using statistical parametric mapping (SPM) of paired ictal-interictal SPECTs to identify regions of significant ictal hyperperfusion and compared clinical characteristics, tracer-injection time, semiology, pathologic HS grade, and surgical outcome between two groups. RESULTS: Of the 39 patients, 19 patients (10 males, nine right HS) were designated as group 1, and the remaining 20 patients (eight males, seven right HS), group 2. Group 1 showed hyperperfusion mainly confined to the ipsilateral temporal lobe, whereas group 2 showed widespread hyperperfusion in the extratemporal structures such as ipsilateral basal ganglia, brainstem, and bilateral thalamus, in addition to the ipsilateral temporal lobe. No significant difference was found between two groups in clinical characteristics, injection time, pathologic HS grade, and surgical outcome. Among semiologic features, dystonic limb posturing was more frequently observed in group 2 (p = 0.006). CONCLUSIONS: Scalp EEG IID frequency in HS-MTLE can be an important determining factor of ictal hyperperfusion patterns. The lack of difference in surgical outcome between two groups implies that different hyperperfusion patterns, according to their IID frequencies, reflect only preferential pathways of ictal propagation rather than intrinsic epileptogenic region.     

Depressive mood in pre-dialytic chronic kidney disease: Statistical parametric mapping analysis of Tc-99m ECD brain SPECT

The purpose of this study was to investigate depression-related regions in pre-dialytic patients with chronic kidney disease (CKD) patients. Participants comprised 33 patients with stage 4 and 5 CKD (age, 55 [42–63]) and 32 healthy volunteers (age, 53.5 [49.5–57]). Depressed mood was assessed in the patients, and both groups underwent Tc-99m-labeled ethylcysteinate dimer (Tc-99m ECD) single photon emission computed tomograpy (SPECT). Statistical parametric mapping identified 18 areas of hypoperfusion in the patients in comparison with the normal controls. The largest clusters were areas including left precentral gyrus, right superior and middle temporal gyrus, both cerebellar posterior lobes, both inferior frontal gyrus, right superior and middle frontal gyrus, right cuneus, right inferior parietal lobule, and right putamen. However, there were no specific hypoperfusion areas in CKD patients with depression compared with CKD patients without depression. Interestingly, several hypoperfusion areas in CKD patients (inferior frontal gyrus [BA46], superior temporal gyrus [BA42], anterior cingulate gyrus [BA24]) were concordant with hypoperfusion areas found in patients with major depression who were free of kidney disease. In conclusion, this study did not demonstrate specific depression-related cerebral hypoperfusion areas. However, the cerebral blood flow pattern in CKD patients was similar to that of patients with major depression in some areas. Although further investigations are needed in the future, we suggest that the causes of the higher prevalence of depression in CKD might be associated with this finding.     

Relative Changes in Regional Cerebral Blood Flow During Spinal Cord Stimulation in Patients with Refractory Angina Pectoris

Spinal cord stimulation applied at thoracic level 1 (T1) has a neurally mediated anti-anginal effect based on anti-ischaemic action in the myocardium. Positron emission tomography was used to study which higher brain centres are influenced by spinal cord stimulation. Nine patients with a spinal cord stimulator for angina pectoris were studied using H₂¹⁵O as a flow tracer. Relative changes in regional cerebral blood flow related to stimulation compared with non-stimulation were assessed and analysed using the method of statistical parametric mapping. Increased regional cerebral blood flow was observed in the left ventrolateral periaqueductal grey, the medial prefrontal cortex [Brodmann area (BA) 9/10], the dorsomedial thalamus bilaterally, the left medial temporal gyrus (BA 21), the left pulvinar of the thalamus, bilaterally in the posterior caudate nucleus, and the posterior cingulate cortex (BA 30). Relative decreases in rCBF were noticed bilaterally in the insular cortex (BA 20/21 and BA 38), the right inferior temporal gyrus (BA 19/37), the right inferior frontal gyrus (BA 45), the left inferior parietal lobulus (BA 40), the medial temporal gyrus (BA 39) and the right anterior cingulate cortex (BA 24). It is concluded that spinal cord stimulation used as an additional treatment for angina applied at TI modulates regional cerebral blood flow in brain areas known to be associated with nociception and in areas associated with cardiovascular control.     

癫痫手术前SPECT的定位价值

目的：了解单光子发射计算机断层扫描（ＳＰＥＣＴ）行局部脑血流检查在致痫灶定位中的应用价值。方法：对２４例癫痫患者行ＳＰＥＣＴ检查，结果采用目测和半定量分析两种方法进行判断。结果：１３／２４（５６％）的患者有目测的异常灌注区，其中１１／１３（８５％）与综合定位的结果相一致，半定量分析的方法可发现１２／１２的患者有异常灌注区，其中１０／１２（８３％）可得到与综合定位结果相一致的结论。统计学显示两种方法在阳性检出率和准确率上有显著差异。结论：ＳＰＥＣＴ在致痫灶的定位中有较高的应用价值，半定量分析的方法可明显提高ＳＰＥＣＴ对致痫灶的检出率，但应将检查结果与临床及其他检查资料相结合进行分析以减少假阳性率     

Mapping of SPECT regional cerebral perfusion abnormalities in obsessive-compulsive disorder

Locations of cerebral perfusion abnormalities in obsessive-compulsive disorder (OCD) were mapped with single photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI). This report is a new, more thorough analysis of a previous study of these subjects that used region-of-interest methods. Ten obsessive-compulsive patients and seven age- and sex-matched control subjects were studied. Image sets were converted into stereotaxic space, normalized to each subject's mean cerebral value, then group averaged. Difference images were calculated and searched for regions with significant between-group cerebral perfusion differences. Obsessive-compulsive patients had significantly higher relative cerebral perfusion in medial-frontal and right frontal cortex and in cerebellum, and significantly reduced perfusion in right visual association cortex. Increased frontal Perfusion agrees with several prior reports. The caudate nucleus, which has been controversial in neuroimaging studies of OCD, did not display a difference between groups. The results of this study provide information about the locations and extents of cerebral perfusion abnormalities in OCD. Regional abnormalities were compared with those reported in prior functional neuroimaging studies. Issues related to OCD hyperfrontality and frontal lateralization of psychopathology are discussed. Normal caudate nucleus findings are considered in relation to prior functional imaging studies and hypotheses of OCD pathology. © 1994 Wiley-Liss, Inc.     

SPECT imaging of cerebral blood flow changes induced by acute trigeminal nerve stimulation in drug-resistant epilepsy. A pilot study

ObjectiveTo explore the cortical areas targeted by acute transcutaneous trigeminal nerve stimulation (TNS) in patients with drug-resistant epilepsy (DRE) using single photon emission computed tomography (SPECT).MethodsTen patients with DRE underwent brain SPECT at baseline and immediately after a 20-minute TNS (0.25 ms; 120 Hz; 30 s ON and 30 s OFF) applied bilaterally to the infraorbital nerve. The French Color Standard International Scale was used for qualitative analyses and z-scores were used to calculate the Odds Ratio (OR).ResultsAt baseline global hypoperfusion (mainly in temporo-mesial, temporo-parietal and fronto-temporal and temporo-occipital areas) was detected in all patients. Following TNS, a global increase in cortical tracer uptake and a significant decrease in median hypoperfusion score were observed. A significant effect favoring a general TNS-induced increase in cortical perfusion (OR = 4.96; p = 0.0005) was detected in 70% of cases, with significant effects in the limbic (p = 0.003) and temporal (p = 0.003) lobes. Quantitative analyses of z-scores confirmed significant TNS-induced increases in perfusion in the temporal (+0.59 SDs; p = 0.001), and limbic (+0.43 SDs; p = 0.03) lobes.ConclusionShort-term TNS is followed a global increase in cortical perfusion, namely in the temporal and limbic lobes.SignificanceThe TNS-induced perfusion increase may reflect neurons’ activity changes in cortical areas implicated in the epilepsy network.     

Evaluation of brain perfusion SPECT using an easy Z-score imaging system (eZIS) as an adjunct to early-diagnosis of neurodegenerative diseases

The eZIS allows computer-assisted statistical analysis of brain perfusion SPECT images. We evaluated the diagnostic value of brain perfusion SPECT using eZIS in patients with various neurodegenerative diseases at a very early stage, within one year from onset.

Methods

SPECT using eZIS was performed for patients with Alzheimer disease (AD), dementia with Lewy bodies (DLB), frontotemporal dementia (FTD,), idiopathic Parkinson disease (PD) and vascular Parkinsonism (VP), multiple systemic atrophy of the cerebellar type (MSA-C), cortical cerebellar atrophy (CCA) and amyotrophic lateral sclerosis (ALS).

Results

Decreased rCBF was observed in the posterior cingulate cortex, precuneus and parietal cortex in AD; in the frontal gyrus and insula in FTD; in the occipital lobe, precuneus gyrus and posterior cingulate cortex in DLB; in the striatum and the thalamus in VP; in the cerebellum in CCA; in the cerebellum and pons in MSA-C and in the frontal cortex including the central sulcus in ALS. Increased rCBF in the striatum, thalamus and cerebellar dentate nuclei were observed in PD.

Conclusions

A specific rCBF pattern was observed for each disease using eZIS analysis, consistent with previous reports. Our results showed eZIS can be easily used as an adjunct to early-diagnosis of neurodegenerative diseases in any hospital.     

Utility of interictal SPECT of rCBF for focal diagnosis of the epileptogenic zone(s)

With Single Photon Emission Computed Tomography (SPECT) of regional cerebral bloodflow (rCBF) ictally and interictally, regional changes of rCBF can be detected in many cases with medically intractable complex partial seizures. Interictal SPECT shows abnormal rCBF in the epileptogenic temporal lobe in 40% to 85% of the patients. A critical survey of the methodological problems considering isotopes, scanners, data analysis and patient population is presented here as well as a few semi-quantitative studies including our own. It is concluded, that SPECT of rCBF is a useful, non-invasive method of localizing the epileptogenic zone in patients with severe partial focal epilepsy. Ictal SPECT of rCBF has a higher predictive value and is more sensitive than interictal studies for localization of the seizure focus. Interictal SPECT using a high-resolution system obtains an almost as high frequency of localization of the focus. With low resolution scanners, a minor frequency is observed. Both interictal and ictal SPECT recordings should be obtained for localization of the epileptogenic focus in presurgical cases as interictal hypoperfusion and ictal hyperperfusion demonstrated in the same focal area are highly characteristic of a seizure focus.     

Functional assessment of intracranial arachnoid cysts with TC99 m-HMPAO SPECT: a preliminary report

Background Many arachnoid cysts (AC) are detected incidentally in asymptomatic patients. Current neuroimaging methods provide only morphological details of the cysts, but they do not give information about cerebral function. While surgery is indicated in symptomatic patients, the management of asymptomatic individuals, who present with large cysts, is controversial.Study objective To ascertain the value of cerebral 99 mTc-HMPAO single photon emission computed tomography (SPECT) for detecting brain dysfunction in cases of intracranial ACs, aimed at allocating the patients for surgical or for conservative treatment.Patients and methods We studied prospectively 11 patients diagnosed with sylvian fissure ACs. The subjects underwent neurological examination, EEG, neuroimaging studies, neuropsychological testing, and cerebral perfusion studies with 99 mTc-HMPAO SPECT.Results The patients’ ages ranged from 2 to 42 years (median 16 years). The study group consisted of ten symptomatic patients with ACs and one patient with an incidental cyst. Seven patients showed diminished regional cerebral blood flow (rCBF) in their initial cerebral SPECT. Four individuals underwent surgery. Seven patients showed normalization of rCBF after surgical or conservative treatment.Conclusions Cerebral SPECT demonstrated impaired brain perfusion in 70% of symptomatic patients. The zone of decreased rCBF corresponded well with clinical symptoms and with neuroimaging findings. Patients exhibiting normal rCBF in SPECT studies remained or became asymptomatic during the follow-up time. Cerebral SPECT constitutes a valuable adjunct tool for correlating regional function with brain anatomy, and may be of help to allocate patients with ACs for surgical treatment or clinical observation. Further research on this field is warranted.     

Hypoperfusion following encephalitis: SPECT with acetazolamide

At 4 weeks and 8 months following initial symptoms, we performed single-photon emission computed tomography (SPECT) with acetazolamide (ACZ) testing in a patient recovering from acute encephalitis, possibly acute disseminated encephalomyelitis (ADEM). Both regional hypoperfusion at baseline and diminished cerebrovascular reserve were seen after focal hyperintensities had disappeared in magnetic resonance imaging (MRI). The time course of SPECT abnormalities reflected the clinical course more closely than the time course of MRI abnormalities. Thus, persistent cerebral circulatory impairment probably contributed to cognitive and language deficits observed at the subacute stage.     

Measured volumes using segmented tissue probability data obtained using statistical parametric mapping 12 were not influenced by the contrasts of analyzed images

The aim of this study was to evaluate changes in measured volumes using Statistical Parametric Mapping (SPM) 12 caused by contrast changes in magnetic resonance (MR) image. Twenty-one healthy subjects participated in the study. From all subjects, 3D T1-weighted images (T1WIs) were obtained using a 3T scanner. In the first step of creating reference volume data, we used SPM12 to binarize all the segmented data. In the second step, we assigned simulated 3D-T1WI signal intensities to each tissue image and used the following values. The last step was integration of each tissue image to generate 3D-T1WI simulated reference volume data for each participant. To create the reference 3D-T1WIs with various contrasts from the reference volume data, we varied the signal intensity of gray matter from 900 to 600, 700, 1100, 1300, and 1400. The reference 3D-T2WI was acquired using the method used for 3D-T1WIs. Then, six 3D-T1WIs were processed using intrasubject bias-correction processing with SPM12, resulting in six new 3D-T1WIs of nonuniform signal intensities. Thirteen volume data sets were segmented into native-space tissue probability data using SPM12. Examination of the 3D data without nonuniform signal intensity showed that significant differences in measured volumes were not observed on repeated analysis of variance, but examination of the 3D data with nonuniform signal intensity did show significant differences in measured volumes in gray matter and CSF but not in white matter. Measured volumes using segmented tissue probability data obtained using SPM12 were not influenced by the contrasts of analyzed images.     

The usefulness of subtraction ictal SPECT coregistered to MRI in single- and dual-headed SPECT cameras in partial epilepsy

PURPOSE: To prove the clinical usefulness of SISCOM and compare SISCOM images derived from single- and dual-headed single-photon computed tomography (SPECT) cameras for localization of partial epileptic seizures. METHODS: We retrospectively studied 38 partial epilepsy patients, using subtraction SPECT coregistered to magnetic resonance imaging (MRI; SISCOM). SPECT imaging of the first 15 patients was performed by single-headed camera, and the next 23 patients by dual-headed camera. Side-by-side ictal-interictal SPECT evaluation and SISCOM images were blindly reviewed and classified as either localizing to one of 16 sites or nonlocalizing. A third reviewer evaluated cases of disagreement between primary reviewers. Results were compared with seizure localization by any of the following three traditional techniques: surgical outcome, invasive, and noninvasive video-EEG monitoring. The results from the single- and dual-headed SPECT cameras were compared. RESULTS: Reviewers localized areas of hyperperfusion with SISCOM images more often than with side-by-side SPECT evaluation (71.0 vs. 47.4%; p = 0.01). When we compared results of SPECT evaluation with traditional techniques, SISCOM showed greater concordance than side-by-side SPECT evaluation (60.53 vs. 36.84%; p = 0.006). There were no differences in localization between images derived from single- and dual-headed cameras. Concordance of seizure localization, compared with traditional techniques, also was not different between these groups [kappa = 0.38, 95% confidence interval (CI), 0.18-0.58] vs. kappa = 0.63, 95% CI (0.45-0.81)]. CONCLUSIONS: SISCOM is a worthwhile technique for preoperative evaluation in partial epilepsy patients and improves the sensitivity and specificity of seizure localization of SPECT images derived from both single- and dual-headed SPECT cameras.     

脑血管功能储备评估的方法学

应用单光子发射计算机断层(SPECT)结合放射性标记的同位素示踪剂，如IMP、^99mTc-HMPAO与^99mTc-ECD和^133Xe，至今仍作为测定脑血流量(CBF)的金标准。正电子发射断层扫描(PET)可通过放射性同住素标记的氧、葡萄糖或其他化舍物间接地测定CBF。动态的或功能的核磁共振成像通过去氧血红蛋白或氧敏感的成像技术评估CBF。CT成像技术与^133Xe清除率联合应用测定CBF，从1978年至今，仍可视为另一种CBF测定的金标准，其敏感性与特异性均超过60％。TCD作为无创的脑血流速度检测技术，直到1990年以后才始用于脑血管反应性的检测。所有的上述检测技术或方法，在一些特异的脑血管舒张剂或方法应用之前，均不能准确测定脑血管功能储备(CRC)。只是当这些方法与特异性的脑血管舒张剂或方法，如应用乙酰唑胺、吸入二氧化碳或短时间屏气联合应用时，CRC的检测可成为可能。     

Prospective use of subtraction ictal SPECT coregistered to MRI (SISCOM) in presurgical evaluation of epilepsy

Purpose: In patients with drug‐refractory focal epilepsy, nonlesional magnetic resonance imaging (MRI) or discordant data of presurgical standard investigations leads to failure generating a sufficient hypothesis for electrode implantation or epilepsy surgery. The seizure‐onset zone can be further investigated by subtraction ictal single‐photon emission computed tomography (SPECT) coregistered to MRI (SISCOM). This is an observational study of a large consecutive cohort of patients undergoing prospective SISCOM to generate hypothesis for electrode implantation or site of epilepsy surgery. Methods: One hundred seventy‐five consecutive patients undergoing presurgical evaluation with either nonlesional MRI or discordant data of standard investigations preventing the generation of hypothesis for seizure onset were evaluated with SISCOM. Results were compared to gold standard for seizure onset detection, either electrocorticography (ECoG) and/or postoperative outcome. Key Findings: One hundred thirty patients had successful SPECT injection. Hypothesis for electrode implantation/site of surgery was generated in 74 patients. Forty patients had gold standard comparison. Twenty‐eight patients underwent resective surgery. SISCOM was concordant to site of surgery in 82%. An additional 12 patients underwent invasive EEG monitoring but were not suitable for surgery. SISCOM was concordant multifocal in 75%. Two years postsurgical follow‐up of 26 patients showed favorable outcome in 22 (Engel class I and class II). Significance: SISCOM is a highly valuable diagnostic tool to localize the seizure‐onset zone in nonlesional and extratemporal epilepsies. Outcome in this patient group was unexpectedly good, even in patients with nonlesional MRI. The high correlation with ECoG and site of successful surgery is a strong indicator that outcome prediction in this patient group should be adapted accordingly, which may encourage more patients to undergo electrode implantation and subsequent successful surgery. Statistical analysis showed that SISCOM with shorter duration of seizures, focal seizures, and lesional MRI was more likely to generate implantation hypothesis.     

Localized Cerebral Blood Flow Reductions in Patients With Heart Failure: A Study Using 99mTc-HMPAO SPECT

BACKGROUND AND PURPOSE: Reduced resting global cerebral blood flow has been previously detected in association with heart failure (HF), but it is not clear whether there are brain regions that could be specifically affected by those brain perfusion deficits. The authors used a fully automated, voxel-based image analysis method to investigate, across the entire cerebral volume, the presence of resting regional cerebral blood flow (rCBF) abnormalities in HF patients compared to healthy controls. METHODS: rCBF was evaluated with 99mTc-single-photon emission computed tomography in 17 HF patients (New York Heart Association functional class II or III) and 18 elderly healthy volunteers. Voxel-based analyses of rCBF data were conducted using the statistical parametric mapping software. RESULTS: Significant rCBF reductions in HF patients relative to controls (P<.05, corrected for multiple comparisons) were detected in 2 foci, encompassing, respectively, the left and right precuneus and cuneus and the right lateral temporoparietal cortex and posterior cingulated gyrus. In the HF group, there was also a significant direct correlation between the degree of cognitive impairment as assessed using the Cambridge Mental Disorders of the Elderly Examination and rCBF on a voxel cluster involving the right posterior cingulate cortex and precuneus, located closely to the site where between-group rCBF differences had been identified. CONCLUSIONS: These preliminary findings indicate that posterior cortical areas of the brain may be particularly vulnerable to brain perfusion reductions associated with HF and suggest that functional deficits in these regions might be relevant to the pathophysiology of the cognitive impairments presented by HF patients.