Initial Single Photon Emission Computed Tomography Research Articles

Cardiovascular event risk estimated after coronary revascularization and optimal medical therapy: J-ACCESS4 prognostic study

BackgroundAn assessment of cardiac events and survival using quantitative gated myocardial single-photon emission computed tomography (SPECT) (J-ACCESS) associated several risk factors with cardiac events in Japan. The clinical course after revascularization and/or optimal medical therapy (OMT) was followed in patients with coronary artery disease (CAD) at moderate-to-high risk estimated by software incorporating the J-ACCESS risk model. The present study aimed to determine the relevance of changes in estimated risk to outcomes of these therapies.MethodsThis study included 494 patients with possible or definite CAD who underwent initial pharmacological stress 99mTc-tetrofosmin myocardial perfusion SPECT (MPS) before and eight months after therapy. Major cardiac event risk during 3 years of follow-up was calculated using an equation based on that in the J-ACCESS study. Patients with ≥ 10% cardiac event risk estimated at the first MPS (n = 31) were analyzed and followed up for at least 1 year.ResultsEstimated risk was reduced by ≥ 5% in 14 patients (45%) after therapy. During a follow-up period of 22.1 ± 6.7 months, one patient without such reduction had a major cardiac event. Mean %summed stress scores significantly decreased from baseline to follow-up in patients with and without risk reduction. Left ventricular ejection fraction (LVEF [%]) at rest was significantly increased at the second, compared with the first MPS between patients with, than without risk reduction (57 ± 17 vs. 45 ± 16%, p = 0.001 and 50 ± 11 vs. 49 ± 9%, p = 0.953, respectively).ConclusionsA reduction in cardiac ischemia and an increase in LVEF by revascularization and/or OMT were necessary to avoid cardiac events among patients with moderate-to-high estimated risk, and changes in event risk were quantifiable.

Impact of blood pressure changes in cerebral blood perfusion of patients with ischemic Moyamoya disease evaluated by SPECT

Our aim was to determine the impact of targeted blood pressure modifications on cerebral blood flow in ischemic moyamoya disease patients assessed by single-photon emission computed tomography (SPECT). From March to September 2018, we prospectively collected data of 154 moyamoya disease patients and selected 40 patients with ischemic moyamoya disease. All patients underwent in-hospital blood pressure monitoring to determine the mean arterial pressure baseline values. The study cohort was subdivided into two subgroups: (1) Group A or relative high blood pressure (RHBP) with an induced mean arterial pressure 10–20% higher than baseline and (2) Group B or relative low blood pressure (RLBP) including patients with mean arterial pressure 10–20% lower than baseline. All patients underwent initial SPECT study on admission-day, and on the following day, every subgroup underwent a second SPECT study under their respective targeted blood pressure values. In general, RHBP patients showed an increment in perfusion of 10.13% (SD 2.94%), whereas RLBP patients showed a reduction of perfusion of 12.19% (SD 2.68%). Cerebral blood flow of moyamoya disease patients is susceptible to small blood pressure changes, and cerebral autoregulation might be affected due to short dynamic blood pressure modifications.

Intracranial Artery Stenting May Not Improve Cognitive Function: A Preliminary Study.

Dear Sir: Although cognitive decline in patients with extracranial atherosclerotic artery stenosis (ECAS) may be improved by carotid revascularization [1], the effect of stenting on cognitive dysfunction in patients with intracranial atherosclerosis (ICAS) remains unknown. Although stent placement was not effective in improving overall outcomes of patients with ICAS [2], the value of stenting may have to be reconsidered if the procedure alleviates cognitive dysfunction. We aimed to evaluate changes in cognitive function and perfusion after stent placement in ICAS patients. Consecutive patients undergoing stenting who (1) had significant stenosis (>50%) in the major intracranial arteries and (2) received stenting by consensus of the stroke team (stent group) at the Asan Medical Center, from May 2009 to August 2011, were recruited. Patients who had embolic sources and those with severe cognitive dysfunction who could not undergo neuropsychology (NP) tests were excluded. Control subjects were sex- and age-matched with patients with the same condition, but who refused this procedure for personal reasons. All patients underwent NP evaluations on the day before the stenting (T0) and at the 12-month (T12) follow-up visit. This included Mini-Mental Status Examination (MMSE), Beck’s depression inventory (BDI), and NP tests assessing: (1) attention and executive function—forward/backward digit span test, trail making test A & B (TMT-AB (2) memory—Seoul Verbal Learning Test (SVLT) and Rey Complex Figure Test (RCFT), and (3) visuospatial and constructional function—the clock drawing test. The study was approved by our ethical committee, and all the patients provided informed consent. Diamox brain single-photon emission computed tomography (SPECT) was also performed at T0 and T12 in the stent group [3]. For statistics, the Mann-Whitney U test was used to estimate the differences among continuous variables, and the chi-square and Fisher exact test were used for categorical data. To evaluate the results of NP tests, the differences observed in each patient after 12 months (T12-T0, ΔT12) compared to baseline were calculated. The mean Δ values were compared between the groups. All statistical analyses were conducted using SPSS for Windows (version 18.0; SPSS Inc., Chicago, IL, USA). Eleven patients (mean age: 57.3 years, range 48-73 years) with distal internal carotid artery (ICA) (n=3), middle cerebral artery (MCA) (n=4), basilar artery (BA) (n=2), and distal vertebral artery (VA) (n=2) stenoses and 11 control subjects (mean age: 60.7 years, range 49-72 years) with MCA (n=8) and BA (n=3) stenoses were enrolled. The stenosis severity of these patients averaged 75% (range: 50-100). There were no differences in demography, vascular risk factors, the side and degree of stenosis, the length of education, and MMSE, BDI, NIHSS, and NP tests for various domains of cognition between the two groups. All patients in the stent group underwent successful procedures without any neurological complications, and there was no significant residual stenosis. All patients were followed up for a period of 12 months. Between the two groups, the mean difference between the changes over time in MMSE, BDI, and NP test results for various domains was not significant (Table 1). Initial and follow-up SPECTs were performed in six patients (55%) from the stent group. Initially, all the patients showed decreased perfusion corresponding to the stenosed artery. The perfusion abnormalities of all six patients improved or normalized after stent placement. However, there was no difference in changes of cognitive function even in these six patients. Table 1. Changes in cognitive function during the 12-month period, and comparisons of the differences between the stent and control group The baseline MMSE score in our patients was 26, and the scores from the NP were also generally low, suggesting the presence of diffuse cognitive impairment. This appears to be consistent with a previous study based on transcranial Doppler ultrasonography that reported that low cerebral blood flow velocity was associated with cognitive decline [4]. We found, however, that stent placement did not affect cognition after 1 year, despite the improved cerebral perfusion in these patients. It seems that there may be brain damages associated with stenting that possibly offset the potential beneficial effects of improved perfusion [5]. First, the debris of atherosclerotic plaques could be dislodged during the procedure leading to distal embolization [6]. Generation of microembolic events on transcranial Doppler ultrasonography or new embolic brain lesions detected by diffusion-weighted MRI (DWI) have been reported to occur during or after interventional procedures [7]. In a previous study, cognitive function tended to decrease more significantly in patients receiving stenting than in those undergoing endarterectomy, which may be related to new ischemic lesions that occur twice as often in the former group [8]. As only stenting procedures are feasible in treating ICAS, the adverse effect of interventional procedures on cognitive function may be more apparent in these patients. Second, selective ballooning during the intervention may result in transient cerebral hypoperfusion. In addition, although none of our patients developed overt hyperperfusion syndrome, cerebral hyperperfusion secondary to revascularization may lead to brain damage [9]. Finally, revascularization of a stenosed intracranial artery may lead to perfusion improvement in smaller areas of the brain than in patients receiving carotid revascularization because the stenosed vessels are located distal to the communicating arteries in ICAS patients. The merits of our study included our evaluation of the perfusion before and after stenting using Diamox SPECT, which may influence cognitive improvement. Moreover, we performed follow-up NP tests at a 1-year interval to minimize the learning effect. The limitations of our study included the non-randomized design, the lack of SPECT imaging in the control group, and most importantly, the lack of statistical power due to the small number of enrolled patients. Unfortunately, we had to prematurely terminate our study because the number of stenting cases dramatically plummeted after the negative results of the SAMMPRIS study [2]. However, because we could not see any ‘trend’ of improvement in stented patients, we suspect that the results may have been the same, even if larger number of patients were enrolled. Despite these limitations, our preliminary results suggest that the stenting procedures may not be of benefit in improving cognitive function in ICAS patients.

Identification of diabetes-related dementia: Longitudinal perfusion SPECT and amyloid PET studies

AimsWe attempted to identify a dementia subgroup with characteristics associated with diabetes mellitus (DM)-related metabolic abnormalities, referred to as diabetes-related dementia, using longitudinal single photon emission computed tomography (SPECT) and Pittsburgh compound-B (PiB) positron emission tomography (PET). MethodsWe classified 175 patients with clinically diagnosed Alzheimer disease (AD) and DM into 4 subgroups based on brain imaging in a 2013 study. Among them, we investigated follow-up SPECT studies in 29 patients of an AD group showing decreased regional cerebral blood flow (rCBF) of the parietotemporal lobe on initial SPECT and 18 patients of a diabetes-related dementia group showing neither decreased rCBF of the parietotemporal lobe nor cerebrovascular disease, which is strongly associated with DM-related factors. Eleven of them underwent PiB PET. ResultsFollow-up SPECT showed more profound rCBF reduction in the parietotemporal lobe and other areas of the AD group, whereas follow-up SPECT showed an rCBF reduction in small areas of the frontotemporal and limbic lobes of the diabetes-related dementia group. Six of 9 patients with diabetes-related dementia were negative or equivocal for PiB binding. ConclusionA subset of a dementia subgroup with characteristics predominantly associated with DM-related factors may underlie a pathophysiology different from AD, although these patients were clinically diagnosed as having AD. The identification of diabetes-related dementia may be necessary for considering an appropriate therapy and prevention in clinical practice.

Cost analysis favours SPECT over PET and CTA for evaluation of coronary artery disease: the SPARC study.

There are many ways to perform noninvasive testing in patients with coronary artery disease (CAD), including myocardial perfusion imaging with single-photon emission computed tomography (SPECT), positron-emission tomography (PET), and coronary computed tomography angiography (CTA). Results from series of patients evaluated with single modalities have already been published by many researchers [1–3], but there are few head-to-head comparisons of the outcomes of alternative test strategies [4, 5]. Consequently, the comparative effectiveness of different noninvasive cardiac testing strategies has been difficult to assess. The recently published SPARC registry (Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in Coronary Artery Disease) in JACC by the group of DiCarli et al. (Stanford, CA, USA) was a multicentre study designed to collect standardised clinical data on patients undergoing CTA, PET, or SPECT [6]. The primary purpose of the SPARC study was to evaluate the economic outcomes of using CTA, PET, or SPECT to evaluate patients with suspected CAD. The authors used an observational registry of 1703 patients: 590 patients underwent CTA, 548 patients had PET and 565 patients SPECT for diagnosis of suspected CAD. Patients were followed for 2 years; documented resource use, medical costs for CAD, and clinical outcomes were assessed. The main findings were that costs were significantly lower for SPECT compared with CTA or PET in the evaluation of suspected CAD. SPECT was economically attractive compared with PET, whereas CTA was associated with higher costs and no significant difference in mortality compared with SPECT. More specifically, the authors observed that patients who underwent coronary CTA and PET experienced higher rates of subsequent invasive coronary arteriography (16 % and 15 %, respectively) as compared with patients who underwent SPECT (7 %). The mean total radiation was significantly higher for CTA (15.1 mSV) compared with SPECT (11.7 mSV), both for the initial tests (13 mSV vs. 11 mSV) and for follow-up tests and procedures (2.1 mSV vs. 0.7 mSV). Exposure from follow-up tests and procedures was higher after PET (2.0 mSV) than after SPECT (0.6 mSV). The findings in favour of SPECT are in line with a decision model by Garber and Solomon [7], who compared exercise treadmill testing, stress echocardiography, planar thallium imaging, SPECT, and PET imaging with a strategy of immediate invasive angiography. They found SPECT to be much more cost-effective than PET for noninvasive diagnosis, and SPECT to be a better option than immediate invasive coronary angiography. In terms of outcomes, Shaw et al. [1] found that patients who underwent initial SPECT with selective cardiac catheterisation had lower costs than patients who underwent routine coronary angiography (END study). In the EMPIRE study by Underwood et al. [2] it was demonstrated that strategies using myocardial perfusion imaging were cheaper and equally effective when compared with strategies that did not use myocardial perfusion imaging, both for the cost of diagnosis and for overall 2-year management costs; the 2-year patient outcome was the same. Sharples et al. [8] randomised 898 patients to SPECT, stress echocardiography, magnetic resonance imaging (MRI), or direct invasive coronary angiography, and found SPECT to be as useful as immediate invasive angiography with similar costs. A limitation of the SPARC study is the fact that MRI was not included in the comparative strategies. In addition, as the study started in 2006, in recent years many technological revolutions have taken place for all imaging modalities indicating that studies such as SPARC should be repeated and extended every 5–10 years [9]. Analysis of the current SPARC registry at least suggests that SPECT is the noninvasive imaging procedure of choice to evaluate patients with suspected CAD in terms of subsequent medical costs. SPECT offered the lowest costs over 2 years of follow-up among patients with suspected CAD. The significantly higher costs among patients undergoing CTA or PET were primarily due to higher rates of subsequent invasive cardiac procedures, because there was little difference in initial costs of testing. To conclude, the use of SPECT myocardial perfusion imaging was associated with lower costs over 2 years of follow-up than the use of CTA or PET, primarily because of fewer subsequent invasive procedures. Consequently, SPECT imaging seems to be the preferred imaging strategy in patients with suspected CAD. The value of SPECT imaging has been underscored by several recent reports [10–13]. However, larger and more definitive studies, such as the ongoing PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) trial (NCT01174550), are needed to assess the value and cost effectiveness of the various noninvasive imaging strategies.

Clinical Utility of SPECT Neuroimaging in the Diagnosis and Treatment of Traumatic Brain Injury: A Systematic Review

PurposeThis systematic review evaluated the clinical utility of single photon emission computed tomography (SPECT) in traumatic brain injury (TBI).MethodsAfter defining a PICO Statement (Population, Intervention, Comparison and Outcome Statement), PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) criteria were applied to identify 1600 articles. After screening, 374 articles were eligible for review. Inclusion for review was focus on SPECT in the setting of mild, moderate, or severe TBI with cerebral lobar specificity of SPECT findings. Other inclusion criteria were comparison modalities in the same subjects and articles in English. Foreign language articles, SPECT studies that did not include comparison modalities, and case reports were not included for review.ResultsWe identified 19 longitudinal and 52 cross-sectional studies meeting inclusion criteria. Three longitudinal studies examined diagnostic predictive value. The first showed positive predictive value increases from initial SPECT scan shortly after trauma to one year follow up scans, from 59% to 95%. Subsequent work replicated these results in a larger cohort. Longitudinal and cross sectional studies demonstrated SPECT lesion localization not detected by CT or MRI. The most commonly abnormal regions revealed by SPECT in cross-sectional studies were frontal (94%) and temporal (77%) lobes. SPECT was found to outperform both CT and MRI in both acute and chronic imaging of TBI, particularly mild TBI. It was also found to have a near 100% negative predictive value.ConclusionsThis review demonstrates Level IIA evidence (at least one non-randomized controlled trial) for the value of SPECT in TBI. Given its advantages over CT and MRI in the detection of mild TBI in numerous studies of adequate quality, and given its excellent negative predictive value, it may be an important second test in settings where CT or MRI are negative after a closed head injury with post-injury neurological or psychiatric symptoms.

Rate of progression of Alzheimer's disease in younger versus older patients: A longitudinal single photon emission computed tomography study

Although several researchers have examined the effect of age on disease progression in patients with Alzheimer's disease (AD), the results are controversial. We investigated the effect of age on the rate of progression of cognitive impairment and on regional cerebral blood flow (rCBF) deficits using longitudinal single photon emission computed tomography (SPECT) studies. We divided 75 patients with AD who were followed up for 24-90 months into the younger AD group (n=32, age at initial examination ≤ 75 years) and the older AD group (n=43, age at initial examination >75 years). We assessed changes in Mini-Mental State Examination (MMSE) scores and rCBF between initial and final examinations. The change in the annual MMSE score was greater in the younger AD group than in the older AD group. The mean annual MMSE score changes correlated significantly with age at the initial examination. The initial and follow-up SPECT studies showed more severe and extensive rCBF deficits in the younger AD group than in the older AD group. Our longitudinal SPECT study showed that the rate of progression of cognitive impairment and the rCBF deficits were higher in younger patients with AD than in older patients with AD. Therefore, age is an important factor to consider, not only in the diagnosis, but also in the treatment and prognosis of patients with AD.

Impact of a new ultrafast CZT SPECT camera for myocardial perfusion imaging: fewer equivocal results and lower radiation dose

The new ultrafast cardiac single photon emission computed tomography (SPECT) cameras with cadmium-zinc-telluride (CZT)-based detectors are faster and produce higher quality images as compared to conventional SPECT cameras. We assessed the need for additional imaging, total imaging time, tracer dose and 1-year outcome between patients scanned with the CZT camera and a conventional SPECT camera. A total of 456 consecutive stable patients without known coronary artery disease underwent myocardial perfusion imaging on a hybrid SPECT/CT (64-slice) scanner using either conventional (n = 225) or CZT SPECT (n = 231). All patients started with low-dose stress imaging, combined with coronary calcium scoring. Rest imaging was only done when initial stress SPECT testing was equivocal or abnormal. Coronary CT angiography was subsequently performed in cases of ischaemic or equivocal SPECT findings. Furthermore, 1-year clinical follow-up was obtained with regard to coronary revascularization, nonfatal myocardial infarction or death. Baseline characteristics were comparable between the two groups. With the CZT camera, the need for rest imaging (35 vs 56%, p < 0.001) and additional coronary CT angiography (20 vs 28%, p = 0.025) was significantly lower as compared with the conventional camera. This resulted in a lower mean total administered isotope dose per patient (658 ± 390 vs 840 ± 421 MBq, p < 0.001) and shorter imaging time (6.39 ± 1.91 vs 20.40 ± 7.46 min, p < 0.001) with the CZT camera. After 1 year, clinical outcome was comparable between the two groups. As compared to images on a conventional SPECT camera, stress myocardial perfusion images acquired on a CZT camera are more frequently interpreted as normal with identical clinical outcome after 1-year follow-up. This lowers the need for additional testing, results in lower mean radiation dose and shortens imaging time.

Regional Cerebral Blood Flow Abnormalities in Patients With Kawasaki Disease

Kawasaki disease (KD) is an acute febrile disorder of unknown etiology. Brain single-photon emission computed tomography (SPECT) and magnetic resonance imaging (MRI) help in detecting regional cerebral blood flow abnormalities and brain damage. The usefulness of SPECT and MRI in patients with KD was evaluated. All 22 patients with KD underwent brain SPECT using Tc-99m-hexamethyl propylene amine oxime from 6 days to 3 years after onset, and 8 patients underwent brain MRI. Of the 22 patients, 4 had neurologic symptoms. Case 1 showed prolonged apnea; case 2, prolonged disturbance of consciousness; and cases 3 and 4 generalized tonic-clonic seizures. Initial brain SPECT showed localized hypoperfusion in 4 and 13 patients with and without neurologic symptoms, respectively. All patients with neurologic symptoms underwent follow-up SPECT; localized hypoperfusion was detected between 1- and 6-month follow-up in 3 of these patients. Six patients without neurologic symptoms underwent follow-up SPECT. Localized hypoperfusion was detected at approximately 1- to 11-month follow-up in 4 of these patients. Diffusion-weighted imaging revealed abnormal high-intensity areas in the corpus callosum in case 1. Case 2 showed a bilateral chronic subdural hematoma with decreased size and ischemic changes, and case 3 showed bilateral hippocampal atrophy and left hippocampal sclerosis. Because the occurrence of localized hypoperfusion is possibly not restricted to only the acute phase in KD, brain SPECT and MRI should also be performed in KD patients with neurologic symptoms.

Vascular risk factors are associated with faster decline of Alzheimer disease: a longitudinal SPECT study

We investigated the effects of cardiovascular risk factors, such as hypertension, diabetes mellitus, and hypercholesterolemia, on longitudinal regional cerebral blood flow (rCBF) changes in Alzheimer's disease (AD). We followed 68 outpatients with probable AD for an average of 40 months. They were divided into three groups based on no (n = 24), single (n = 27), and multiple (n = 17) vascular risk factors. We assessed longitudinal changes on the Mini-Mental State Examination, Functional Assessment Staging scores, and in rCBF deficits using repeated single photon emission computed tomography (SPECT) using N-isopropyl-p-[(123)I] iodoamphetamine. During follow-up, the multiple vascular risk factor group showed faster cognitive and functional decline than the no and single vascular risk factor groups. When compared with the initial SPECT, the follow-up SPECT showed a significant rCBF reduction in widespread regions, including the parietotemporal, frontal, and limbic lobes, in the multiple and single vascular risk factor groups, while there was rCBF reduction in small scattered regions of the temporoparietal lobe in the no vascular risk factor group. Multiple vascular risk factors are associated with a greater rate of decline in cognition, function, and rCBF in patients with AD. Our results highlight the contribution of vascular risk factors on the progression of AD.

A Longitudinal SPECT Study of Different Patterns of Regional Cerebral Blood Flow in Alzheimer’s Disease with or without Diabetes

Aims: To determine the effect of diabetes mellitus (DM) on regional cerebral blood flow (rCBF) patterns in patients with Alzheimer’s disease (AD). Methods: We investigated the initial rCBF of 71 AD patients (36 without DM and 35 with DM) and the final rCBF of 23 AD patients (12 without DM and 11 with DM) after an average of 32 months. Single-photon emission computed tomography (SPECT) data were analyzed by statistical brain imaging. Results: The initial SPECT showed that AD patients without DM had lower rCBF in the left and right inferior temporal gyri than AD patients with DM. A follow-up SPECT demonstrated that rCBF decreased in more widespread regions, including the parietal, temporal, frontal, and limbic lobes, in AD patients without than with DM. Conclusion: This study suggests that functional brain abnormalities in AD differ depending on the DM status at baseline and during follow-up, reflecting neuropathologic differences.

Cerebellar Hypoperfusion during Transient Global Amnesia: An MRI and Oculographic Study

Background and purposeTransient global amnesia (TGA) is characterized by sudden anterograde and retrograde amnesia lasting for up to 24 hours. Diffusion-weighted magnetic resonance imaging (DWI) in cases of TGA and ischemia demonstrates a high frequency of high signal intensities restricted to the hippocampus, and this has been proposed as an etiology of TGA. The aims of this study were to characterize the DWI and single-photon-emission computed tomography (SPECT) findings during the acute and recovered phases of TGA and to correlate the findings with oculomotor abnormalities.MethodsFive consecutive patients with a clinical diagnosis of TGA underwent DWI and SPECT of the brain within 24 hours after symptom onset and again 3 days later. Eye movements were also recorded using three-dimensional video-oculography.ResultsIn all patients, DWI disclosed small punctuate (1-3 mm), high-signal lesions in the lateral portion of the hippocampus. The initial SPECT also revealed hypoperfusion in the cerebellar vermis, which had recovered by the follow-up examination. Three patients showed saccadic hypermetria or impaired smooth pursuit only during the acute phase.ConclusionsOur patients with TGA showed cerebellar vermian hypoperfusion in addition to ischemic insults to the lateral hippocampus. The oculomotor abnormalities observed in our patients support the occurrence of cerebellar dysfunction during the TGA attack.

Early Dynamic SPECT Imaging in Acute Viral Encephalitis

Several cases have reported that dynamic single-photon emission computed tomography (SPECT) shows increased tracer uptake in acute herpes simplex viral encephalitis (HSVE). The purpose of this study was to evaluate the clinical usefulness of dynamic Tc-ECD SPECT in patients with acute viral encephalitis. We performed the dynamic SPECT in 9 patients with acute viral encephalitis (4 women, 5 men, 49.5 +/- 17.4 years of age at onset). SPECT and magnetic resonance imaging (MRI) were performed within 2 weeks after acute clinical onset and at the time of resolution of acute symptoms. Cranial MRI showed high intensities in all patients (7 medial temporal and 2 lateral temporal lobes, 1 inferior temporal lobe, 2 insula and adjacent regions, 1 thalamus, 1 putamen). The initial dynamic SPECT showed increased accumulation of tracer, corresponding to the lesions on MRI in 3 patients with HSVE. Resolution of acute symptoms was associated with a reduction in increased tracer uptake. Six patients with non-HSVE showed no increased accumulation of tracer. Dynamic SPECT may be a new optional neuroradiologic technique that may help to establish a diagnosis in patients with suspected HSVE.

SPECT in periodic lateralized epileptiform discharges (PLEDs): A case report on PLEDs

Periodic lateralized epileptiform discharges (PLEDs), which are known as unusual electroencephalogram (EEG) patterns, are described in a patient who had stroke and seizures. This patient underwent Tc-99m HMPAO (hexamethyl propylene amine oxime) brain single photon emission computed tomography (SPECT) imaging both during PLEDs on EEG and after the cessation of PLEDs. The initial SPECT study revealed increased CBF in the left frontal and parietal cortex extending through the left temporal region and in the left basal ganglium. After the PLEDs disappeared, the second SPECT study showed decreased perfusion on the left frontal and parietal region in the brain. Brain SPECT findings supported the contention that PLEDs may be an ictal phenomenon. Here we also present a review on PLEDs and contributions of brain SPECT as a functional imaging modality to investigate the underlying mechanism of this interesting EEG pattern.

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

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. 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. 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. 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. 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.

The prediction of rapid conversion to Alzheimer's disease in mild cognitive impairment using regional cerebral blood flow SPECT

Mild cognitive impairment (MCI) comprises a heterogeneous group with a variety of clinical outcomes and they are at risk for developing Alzheimer's disease (AD). The prediction of conversion from MCI to AD using the initial neuroimaging studies is an important research topic. We investigated the initial regional cerebral blood flow (rCBF) measurements using single photon emission computed tomography (SPECT) in individuals with 76 amnesic MCI (52 subjects converted to AD and 24 subjects did not convert to AD at 3-year follow-up) and 57 age- and gender-matched controls. We sought functional profiles associated with conversion to AD, then evaluated the predictive value of the initial rCBF SPECT. As compared with controls, AD converters demonstrated reduced blood flow in the bilateral parahippocampal gyri, precunei, posterior cingulate cortices, bilateral parietal association areas, and the right middle temporal gyrus. Non-converters also demonstrated significant reduction of rCBF in the posterior cingulated cortices and the right caudate nucleus when compared to controls. As compared with non-converters, converters showed reductions of rCBF in the bilateral temporo-parietal areas and the precunei. The logistic regression model revealed that reduced rCBF in the inferior parietal lobule, angular gyrus, and precunei has high predictive value and discriminative ability. Although a cross-validation study is needed to conclude the usefulness of rCBF SPECT for the prediction of AD conversion in individuals with MCI, our data suggest that the initial rCBF SPECT studies of individuals with MCI may be useful in predicting who will convert to AD in the near future.

Case Series: Neuropsychiatric Symptoms With Pediatric Systemic Lupus Erythematosus

To describe the psychiatric presentation, serologic findings, and neuroimaging patterns in children and adolescents with central nervous system involvement with systemic lupus erythematosus (CNS-SLE). Pediatric patients with psychiatric symptoms who fulfilled the 1997 revised diagnostic American College of Rheumatology criteria for SLE were studied. Complement levels, and anti-double-stranded DNA, anti-Smith, anti-phospholipid, and anti-neuronal antibodies were evaluated. Computed tomography, magnetic resonance imaging, and single photon emission computed tomography (SPECT) neuroimaging studies were reviewed. The 10 patients with CNS-SLE presented with psychosis, mood disturbance, or confusion, and 8 patients had concomitant neurologic symptoms. The 8 girls and 2 boys ranged in age from 7.5 to 17 years. Serum anti-neuronal antibodies were positive with onset of symptoms and declined with improvement. Initial SPECT was abnormal in all 10 patients and remained abnormal. SPECT and anti-neuronal antibodies help confirm CNS involvement in patients with SLE and neuropsychiatric symptoms.

Quantitative assessment with SPECT imaging of stress injuries of the pars interarticularis and response to bracing.

The evaluation and management of acute spondylolysis remains unclear in part because of outcome data that are primarily subjective. The aim of this study was to evaluate and monitor these patients objectively using quantitative single-photon emission computed tomography (SPECT). Thirty-four patients were so observed clinically between 1987 and 1996 and were studied with an initial and at least one follow-up SPECT scintigram. Initial radiographs and planar bone scans failed to demonstrate the pars lesion in 53 and 19% of the patients, respectively. The average SPECT ratio before brace treatment was 1.45. After treatment, this ratio significantly decreased to 1.27 (p = 0.03). A subset of patients remained symptomatic at follow-up. Their reduction in SPECT ratio averaged only 2.8% as compared with 13% for the remainder of the patients (p = 0.01). Patients diagnosed and braced in the early, more active stage of the condition (with greater intensity on SPECT) had more predictable symptom relief. An initial SPECT ratio of >1.5 was associated with complete symptom resolution after brace treatment. Patients treated with activity restriction only (>3 months) before bracing were more likely to have persistent symptoms and more modest improvement on SPECT (p = 0.01). These data, which use SPECT scintigraphy, support prompt treatment with brace immobilization for acute spondylolysis in children and adolescents.

Selection Criteria for Intra-Arterial Thrombolytic Therapy by Initial SPECT

We determined the selection criteria for intra-arterial thrombolytic therapy by initial single-photon emission-computed tomography (SPECT) using 99mTc-HMPAO. We studied 30 patients who were obtained early complete recanalization of the internal carotid territory occlusion. The residual CBF of non-infarction, infarction and hemorrhagic lesions judged by follow-up CT scan was evaluated semiquantitatively by calculating two parameters with pretherapeutic SPECT: the ischemic regional activity to cerebellar activity ratio (R/CE ratio) and asymmetry index (AI). The patient's neurological exam was evaluated according to the NIH stroke scale score. The patients were classified by follow-up CT into three groups: A) nine patients who had no or small infarction; B) fourteen patients who had medium or large cortical infarction; C) seven patients who had hemorrhagic transformation. No significant difference was observed in the interval from onset, UK doses, or site of occlusion between each group. However, the residua...

Potential cost effectiveness of initial myocardial perfusion imaging for assessment of emergency department patients with chest pain

Previous investigations have confirmed the diagnostic and predictive usefulness of initial single-photon emission computed tomography (SPECT) myocardial perfusion imaging using technetium-99m sestamibi in the evaluation of emergency department patients with chest pain. Patients with a normal SPECT perfusion scan performed during chest pain have an excellent short-term prognosis, and may be candidates for expeditious cardiac evaluation or outpatient management. However, there are limited data regarding the cost effectiveness of this technique. This analysis models the potential cost effectiveness of this procedure.In the current investigation we compared 2 model strategies for management of emergency department patients with typical chest pain and a normal or nondiagnostic electrocardiogram (ECG). In 1 model strategy, (the technetium-99m sestamibi SPECT myocardial perfusion imaging [SCAN] strategy), the decision whether to admit or discharge a patient from the emergency department is based on results of initial technetium-99m sestamibi SPECT myocardial imaging. Patients with normal scans are discharged; others are admitted. In the second model strategy, (the NO SCAN strategy), the decision whether or not to admit a patient is based on a combination of clinical and electrocardiographic variables. Patients with ≥3 cardiac risk factors or an abnormal ECG are admitted; others are discharged. Adverse cardiac events were prospectively defined as cardiac death, nonfatal myocardial infarction, or the need for acute coronary intervention. Costs were assigned using data derived from 102 patients who underwent SPECT myocardial perfusion imaging and an additional 107 emergency department patients with ongoing chest pain who either underwent or were eligible for initial SPECT myocardial perfusion imaging.Mean (± SE) costs were highest among hospital admitted patients who experienced an adverse cardiac event ($21,375 ± $2,733) and lowest in patients discharged from the emergency department ($715 ± 71). Mean costs per patient of the SCAN strategy and NO SCAN strategy were $5,019 versus $6,051, respectively. These results were stable in a sensitivity analysis across a range of costs and predictive values.Thus, the SCAN model strategy for initial management of emergency department patients with typical ongoing angina and a normal or nondiagnostic ECG using initial myocardial perfusion imaging with technetium-99m sestamibi appears to be safe, accurate, and potentially cost effective. Validation of these preliminary retrospective observations will require further prospective investigation.