Simultaneous SPECT studies of pre- and postsynaptic dopamine binding sites in baboons.

The central nervous system dopamine transporters (DATs) and dopamine D2/D3 receptors are implicated in a variety of neurological disorders. Both sites are also targets for drug treatment. With the successful development of [99mTc]TRODAT-1, single-isotope imaging studies using this ligand for DAT imaging can be complemented by additional use of 123I-labeled D2/D3 receptor ligand co-injected to assess both pre- and postsynaptic sites of the dopaminergic system simultaneously. METHODS: Twelve SPECT scans of the brain were obtained in two baboons after intravenous administration of 740 MBq (20 mCi) [99mTc]-TRODAT-1 (technetium, [2-[[2-[[[3-(4-chlorophenyl)-8-methyl-8-azabicyclo[3,2,1]oct-2-yl]methyl ](2-mercaptoethyl) amino]ethyl]-amino]ethanethiolato (3-)]- oxo-[1R-(exo-exo)]) and 185 MBq (5 mCi) [123I]iodobenzamide or [123I]iodobenzofuran. SPECT data were acquired by a triple-head gamma camera equipped with ultra-high-resolution fanbeam collimators (scan duration = 210 min). Two sets of SPECT data were obtained using energy windows of 15% centered on 140 keV for 99mTc and 10% asymmetric with a lower bound at 159 keV for 123I. After coregistration with MRI, region-of-interest analysis was performed using predefined templates from coregistered MRI. In blocking studies, baboons were pretreated with N-methyl-2beta-carbomethoxy-3beta-(4-fluorophenyl)tropane (CFT, 14 mg) or raclopride (14 mg) to block DAT or D2/D3 binding site, respectively. RESULTS: Image quality of dual-isotope studies was similar to that obtained from single-isotope studies. When one site was blocked with CFT or raclopride, the binding of the respective ligand to the other site was not affected. CONCLUSION: This is the first example that clearly demonstrates the feasibility of simultaneous imaging of both pre- and postsynaptic sites of the dopaminergic system in baboons with dual-isotope SPECT studies. With or without corrections for cross-contamination of 123I into the 99mTc window, striatum-to-cerebellum ratios (target-to-nontarget) of dual-isotope experiments did not differ significantly from single-isotope experiments. This method may be a valuable and cost-effective tool for gaining comprehensive information about the dopaminergic system in one SPECT imaging session.     

Dual-tracer dopamine transporter and perfusion SPECT in differential diagnosis of parkinsonism using template-based discriminant analysis.

Clinical differential diagnosis in parkinsonism can be difficult especially at early stages. We investigated whether combined perfusion and dopamine transporter (DAT) imaging can aid in the differential diagnosis of parkinsonian disorders: idiopathic Parkinson's disease (IPD), progressive supranuclear palsy (PSP), multiple system atrophy (MSA), dementia with Lewy bodies (LBD), and essential tremor (ET). METHODS: One hundred twenty-nine patients were studied, retrospectively (69 males; 24 MSA, 12 PSP, 8 LBD, 27 ET, and 58 IPD; mean disease duration, 3.5 +/- 3.7 y). Diagnosis was based on established clinical criteria after follow-up of 5.5 +/- 3.8 y in a university specialist movement disorders clinic. Group characterization was done using a categoric voxel-based design and, second, a predefined volume-of-interest approach along Brodmann areas (BA) and subcortical structures, including striatal asymmetry and anteroposterior indices. Stepwise forward discriminant analysis was performed with cross-validation (CV) using the leave-one-out technique. RESULTS: Characteristic patterns for perfusion and DAT were found for all pathologies. In the parkinson-plus group, MSA, PSP, and LBD could be discriminated in 100% (+CV) of the cases. When including IPD, discrimination accuracy was 82.4% (99% without CV). 2beta-Carbomethoxy-3beta-(4-iodophenyl)nortropane imaging as a single technique was able to discriminate between ET and neurodegenerative forms with an accuracy of 93.0% (+CV); inclusion of perfusion information augmented this slightly to 97.4% (+CV). CONCLUSION: Dual-tracer DAT and perfusion SPECT in combination with discrimination analysis allows an automated, accurate differentiation between the most common forms of parkinsonism in a clinically relevant setting.     

Diagnostic performance of a 3-D automated quantification method of dopamine D2 receptor SPECT studies in the differential diagnosis of parkinsonism

BACKGROUND: Assessment of post-synaptic D2 receptors with 123I-IBZM SPECT is helpful in distinguishing idiopathic (IPS) from other parkinsonian syndromes (non-IPS). AIM: To evaluate the diagnostic performance of a recently introduced three-dimensional automated quantification method in a large group of parkinsonian patients. METHODS: IBZM SPECT was performed in 101 consecutive patients with IPS (n = 49) and non-IPS (n = 52). Striatal/frontal cortex binding ratios were assessed by a standard manual quantification method and by the automated method. For the latter patient studies were registered to a mean template of healthy controls (n = 13). IBZM binding was calculated from a 3-D volume-of-interest map established on the normal template. The diagnostic performance of the automated and manual approaches were assessed by receiver operating characteristic (ROC) analyses. RESULTS: Specific striatal binding ratios of both quantification methods showed a close linear relationship (y = 0.81x + 0.1188; R2 = 0.8062). At optimal decision thresholds sensitivity and specificity were 87% and 90% for the automated, and 85% and 90% for the manual method, respectively. The area under the ROC curve was 0.92 for the automated and 0.93 for the manual method, showing no statistical difference. The area under the ROC curve corresponding to a false positive fraction from 0% to 20% was 0.163 for the automated and 0.166 for the manual evaluation. CONCLUSIONS: The diagnostic performance of an automated 3-D quantification method for IBZM SPECT studies has been shown to be equal to, or even better than, a standard manual technique. Advantages of automated quantifications are observer independence and fast processing times. This method may be also used as a platform for processing large data sets/multicentre studies in order to objectively evaluate basal ganglia disorders.     

123I-FP-CIT SPECT imaging of dopamine transporters in patients with cerebrovascular disease and clinical diagnosis of vascular parkinsonism.

The purpose of our study was to prospectively evaluate the striatal uptake of 123I-labeled N-(3-fluoropropyl)-2beta-carbomethoxy-3beta-(4-iodophenyl)nortropane (FP-CIT) and the response to l-dopa therapy in patients with cerebrovascular disease (CVD) who develop clinical symptoms of vascular parkinsonism (VP). METHODS: Twenty consecutive patients who developed VP in the course of CVD were prospectively enrolled in the study. All patients had CT evidence of CVD (17 patients had lacunar infarcts, 3 patients had territorial strokes). The clinical stage of the patients was assessed using the Hoehn and Yahr scale, and the severity of the symptoms was measured using the Unified Parkinson's Disease Rating Scale score. Ten age-matched subjects were used as controls. SPECT was performed 180 min after injection of 185 MBq 123I-FP-CIT using a dual-head gamma-camera. The ratio of the mean specific-to-nonspecific striatal binding for the entire striatum, caudate, and putamen was calculated in all patients and compared with that of controls. Putamen-to-caudate binding ratios were compared as well. The response to therapy was compared between patients with normal and abnormal 123I-FP-CIT binding. RESULTS: No correlation was found between any of the clinical variables and response to therapy in patients with VP. Nine patients had normal striatal 123I-FP-CIT binding with no significant differences in striatal or subregional binding ratios compared with those of the controls. In contrast, 11 patients had significantly diminished striatal binding compared with that of controls (P < 0.001). Subanalyses showed significantly decreased binding in the caudate (P < 0.04 and P < 0.01 for the right and left caudate, respectively), diminished binding in the putamen (P < 0.04 and P < 0.01 for the right and left putamen, respectively), and a decreased putamen-to-caudate ratio on the right side (P < 0.001). The latter ratio was not significant on the left. Two of the 3 patients with territorial strokes had significantly diminished striatal 123I-FP-CIT binding in the hemisphere contralateral to the CT lesion. All 9 patients with normal scan findings had a poor response to L-dopa. Six of 11 patients with abnormal studies had no response to L-dopa, whereas 5 patients had a good response (P < 0.03). CONCLUSION: The diagnosis of VP cannot be accurately confirmed on the basis of clinical features alone because CVD may alter the typical presentation of PD. Functional imaging with 123I-FP-CIT is highly recommended in patients with CVD who develop symptoms of VP to confirm or exclude the existence of nigrostriatal dopaminergic degeneration. Identifying a subset of patients with reduced 123I-FP-CIT binding in the striatum is important for better treatment selection.     

脑多巴胺转运蛋白显像剂99Tcm-TRODAT-1的SPECT显像

目的探讨脑多巴胺转运蛋白显像剂99Tcm-2β-[N,N′-双(2-巯乙基)乙撑二胺基]甲基,3β-(4-氯苯基)托烷(TRODAT-1)SPECT显像对帕金森病(PD)的诊断价值.方法对30例PD患者及16例健康志愿者行99Tcm-TRODAT-1脑SPECT显像.用2种半定量方法分析①应用感兴趣区(ROI)技术计算双侧横断面、矢状面纹状体(ST)/小脑(CB)放射性摄取比值(ST/CB);②取横断面基底节,将其划分成左、右ST,左、右尾状核和左、右壳核6个ROI,CB和枕叶皮质(OC)作为本底参考区,计算基底节ROI的放射性摄取比值[ROI/(CB+OC/2)].结果对照组横断面、矢状面左、右侧ST/CB分别为1.55±0.15、1.58±0.14和1.62±0.17、1.69±0.16.PD患者ST/CB和ROI/(CB+OC/2)均比对照组明显减低,差异有显著性(P＜0.001).计算矢状面双侧ST/CB更合理.根据ROI/(CB+OC/2)可获得基底节各神经核团放射性分布半定量数据.结论99Tcm-TRODAT-1脑SPECT显像是诊断PD的有效方法.     

Postsurgical cerebral perfusion changes in idiopathic normal pressure hydrocephalus: a statistical parametric mapping study of SPECT images.

Our goal was to study cerebral blood flow (CBF) changes after surgery in a group of 15 patients with idiopathic normal pressure hydrocephalus (NPH). METHODS: We used hexamethylpropyleneamine oxime SPECT and statistical parametric mapping (SPM), an image analysis method that does not require prior selection of regions of interest. RESULTS: Our study showed areas of significant increase in perfusion in specific regions of both frontal lobes and the right parietal lobe. Regions of increased perfusion were found in the left prefrontal dorsolateral areas (Brodmann's areas 9 and 45 or 47), right frontal premotor area (Brodmann's area 44), right medial prefrontal region (Brodmann's area 10 or 32), right frontal white matter area (superior longitudinalis fasciculus), and right basal ganglia (lenticular nucleus, putamen, and globus pallidus). In the right hemisphere, another region of increased perfusion was found in the inferior parietal lobule (Brodmann's area 40). The 2 areas most related to clinical improvement were Brodmann's area 32 and the frontal part of the left lobule of Reil insula. CONCLUSION: The results obtained with the SPM method of image analysis confirm and expand on previous CBF literature in NPH, with specific CBF regions located in frontal and parietal areas that improve after surgery in idiopathic NPH.     

Combined study with FDG PET and Tl SPECT in patients with idiopathic dilated cardiomyopathy

This study aimed to determine whether combined examinations of myocardial 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) and stress-redistribution 201Tl single-photon emission computed tomography (Tl SPECT) were useful in clarifying myocardial ischaemia and evaluating the prognosis in patients with idiopathic dilated cardiomyopathy (IDCM). Twenty-two patients with IDCM underwent echocardiography, cardiac catheterization, FDG PET, and Tl SPECT. In scintigraphic analysis, the total defect score (TDS) was semiquantitatively determined as the sum of scores of the 17 left ventricular (LV) segments with a 5-point scale (0 as normal to 4 as absent). Patients were classified according to the scintigraphic findings as follows: eight patients with small defects on Tl and FDG (TDS < or = 20) (group I), eight patients with small defects on FDG (TDS < or = 20) with FDG uptake increased relative to Tl or 'mismatch' (group II), and six patients with large defects on FDG and Tl (TDS >20) (group III). Eleven patients (50%) showed reversible defects on Tl and all showed preserved FDG uptake. The patients in group III had significantly lower LV ejection fraction (LVEF) (P<0.05, respectively) and a poorer prognosis as shown by the Kaplan-Meier event-free curve compared with those in groups I and II (P<0.01, respectively). Although patients in group II had significantly greater TDS on Tl compared with those in group I (P<0.01), no significant differences in LVEF and prognosis were found between patients in groups I and II. In multivariate analysis, a TDS on FDG revealed an independent predictor of subsequent cardiac events. In conclusion, such mismatched areas can be assumed to consist of impaired but viable myocardium, and may be associated with ischaemia of the microvasculature. Impaired myocardial glucose metabolism is a more powerful predictor of future cardiac events than perfusion abnormality in patients with IDCM.     

Childhood cardiorespiratory fitness and the early markers of kidney disease in middle age: A population-based cohort study

ObjectivesTo investigate the relationship of childhood cardiorespiratory fitness with early markers of chronic kidney disease, glomerular hyperfiltration and albuminuria, in midlife.DesignProspective cohort study.MethodsThis study included 1371 participants aged 36–49 years who participated in the 1985 Australian Schools Health and Fitness Survey when they were 7–15 years of age. Childhood cardiorespiratory fitness was estimated by the time taken to complete a 1.6- km run. Blood and urine samples were collected at follow-up. Log-binomial regression was used to determine the associations of childhood cardiorespiratory fitness with glomerular hyperfiltration [estimated glomerular filtration rate (mL/min/1.73 m²) > 95th percentile standardized for age and sex] and albuminuria (urine albumin-to-creatinine ratio ≥ 2.5 mg/mmol in males or ≥3.5 mg/mmol in females) in midlife.ResultsCompared with women with high childhood cardiorespiratory fitness, those with lower childhood cardiorespiratory fitness had a higher risk of glomerular hyperfiltration in midlife after adjusting for childhood age, the duration of follow-up, and midlife smoking status [adjusted relative risk = 2.86, 95% confidence interval, 1.04–7.86 for individuals with moderate childhood cardiorespiratory fitness (P = 0.04), and adjusted relative risk = 3.38, 95% confidence interval, 1.13–10.14 for individuals with low childhood cardiorespiratory fitness (P = 0.03)]. Further adjustment for childhood and midlife body mass index resulted in a slightly attenuated and statistically non-significant association. No significant associations were found with glomerular hyperfiltration in males or albuminuria in either males or females.ConclusionsLow cardiorespiratory fitness in childhood may increase the risk of glomerular hyperfiltration in midlife in females, possibly via a path through adult cardiorespiratory fitness.     

Crossed cerebello-cerebral diaschisis: a SPECT study.

A scintigraphic single photon emission computed tomographic (SPECT) evaluation of frontal perfusion alteration was performed in five patients with known cerebellar lesions but with normal supratentorial computed tomographic (CT) or magnetic resonance (MR) scans. A clearly evident asymmetry was found in prefrontal areas in the four subjects with acquired cerebellar damage. The fifth subject, who had congenital left cerebellar hypoplasia, did not show any frontal flow asymmetry. The data support the growing clinical evidence that the cerebellum contributes to the cognitive processes of the frontal lobes and suggest a possible role for SPECT examination in the assessment of functional cognitive impairment in patients with acquired cerebellar lesions.     

Clinical features and 123I-FP-CIT SPECT imaging in drug-induced parkinsonism and Parkinson’s disease

Purpose  

To determine clinical predictors and accuracy of ¹²³I-FP-CIT SPECT imaging in the differentiation of drug-induced parkinsonism (DIP) and Parkinson’s disease (PD).     

早期帕金森病患者脑多巴胺D2受体131I-epidepride SPECT显像

目的探讨脑多巴胺D2受体131I-epidepride SPECT显像在早期帕金森病(PD)中的临床价值.方法对10例正常对照者、46例早期未经替代治疗的PD患者[Hoehn&Yahr(H-Y)Ⅰ级22例,H-YⅡ级24例]行多巴胺D2受体131I-epidepride SPECT显像,用感兴趣区技术计算纹状体与枕叶、额叶的放射性比值[(ST-OC)/OC和(ST-FC)/FC].结果正常对照者双侧纹状体摄取无明显差异.PD H-YⅠ级、Ⅱ级患者起病肢体对侧纹状体(ST-OC)/OC和(ST-FC)/FC较同侧均明显上调;随病情加重,纹状体(ST-OC)/OC和(ST-FC)/FC均逐渐增高,与对照组差异明显.结论人脑多巴胺D2受体131I-epidepride SPECT显像有助于PD的早期诊断.     

Prognosis of abdominal aortic aneurysms: a population-based study

Nevitt, Ballard, and Hallett reviewed the charts of virtually all known cases of abdominal aortic aneurysms in residents of Rochester, Minnesota, from 1951 to 1984. Of 370 patients included in this retrospective study, 181 had at least one ultrasound examination; 103 of these had at least two, and 67 had three. Five patients who had leakage or rupture of their aneurysm within 48 hours of their first ultrasound were excluded. The authors found that the median and mean increase in aneurysm size was 0.21 cm and 0.26 cm per year, respectively. There were no cases of rupture in aneurysms less than 5.0 cm in diameter over the course of the study. Aneurysms which on presentation had a diameter of less than 3.5 cm. had a 0% incidence of rupture at eight years. The risk of eventual rupture, following enlargement, for aneurysms 3.5 to 4.9 cm at first ultrasound, was 5% at nine years. Of aneurysms greater than 5.0 cm at the outset, 25% had ruptured by eight years. No significant data regarding rate of change in size relative to risk of rupture were derived. The authors conclude that the rate of expansion of aneurysms is less than the accepted figure of 0.4 cm per year, and that risk of rupture of aneurysms less than 5.0 cm in diameter is much smaller than believed. Because their study is based on a geographically defined rather than referral population, Nevitt et al assert that their data closely approximate the true natural history of abdominal aortic aneurysms.     

External radioactive reference markers in SPECT imaging of the dopamine system.

OBJECTIVE: External radioactive reference markers have been used to localize the canthomeatal (CM) line and correct for head rotation in perfusion brain SPECT. This ensures that regardless of the subject's head position or rotation under the SPECT camera, reconstructed transaxial slices are reoriented parallel to the CM line. This study was undertaken to demonstrate the value of external radioactive reference markers in dopamine SPECT imaging. METHODS: We compared visual and marker methods of reorienting the transaxial slices between dopamine and perfusion brain SPECT studies, respectively. These consisted of imaging normal controls and patients with Alzheimer's or Parkinson's disease using a triple-head camera. Intra- and interoperator variability of the visual and marker methods of reorientation was determined for both perfusion and dopamine studies. RESULTS: In both intra- and interoperator studies, the variability of image reorientation was significantly reduced (P = 0.0066 and 0.014, respectively) by using the marker method on dopamine images. The variability of reorientation using the marker method for a single operator with dopamine images was 3.0% coefficient of variation (CV), and for the interoperator study (5 different operators) this was 7.0% CV. CONCLUSION: This study demonstrated that SPECT imaging of the dopamine system with external radioactive reference markers significantly reduced the variability of determining the angle of reorientation. This resulted in a standardized and consistent method of reorienting transaxial slices, allowing comparison within and between subjects of pre- and postsynaptic dopamine SPECT studies.     

Technetium HMPAO SPECT study in dementia with Lewy bodies, Alzheimer's disease and idiopathic Parkinson's disease.

The aim of this study was to compare the regional cerebral blood flow measurements studied by SPECT in dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) to determine the contribution of SPECT to the differential diagnosis of these two diseases. METHODS: SPECT analysis with 99mTc-hexamethyl propyleneamine oxime (HMPAO) was performed in 20 patients with probable DLB, 20 patients with probable AD and 20 patients with idiopathic Parkinson's disease (IPD). Ten pairs of regions of interest were analyzed. Tracer uptake was expressed as a corticocerebellar activity ratio. RESULTS: Compared with IPD, in the DLB group there was a global decrease of HMPAO uptake in cortical regions of interest except in the posterior frontal and occipital regions; in the AD group there was limited left temporal and parietal hypoperfusion. In the DLB group, frontal HMPAO uptake was significantly lower than in the AD group. Two predictive scores were established by a factorial discriminant analysis from six left cortical indices (medial frontal, lateral frontal, posterior frontal, temporoparietal, parietal and parietooccipital) and the Mini-Mental State Examination, which correctly classified 53 of 60 patients (88%) (DLB, 18 of 20; AD, 16 of 20; IPD, 19 of 20). CONCLUSION: These findings indicate the presence of diffuse cortical abnormalities in DLB and suggest that SPECT may be useful in discriminating in vivo DLB from AD, revealing mainly frontal hypoperfusion in the former group. We estimate that SPECT study increases the possibility of separating DLB and AD because both disorders share different patterns of cerebral blood flow abnormality.     

农村居民糖尿病患者痴呆患病率调查

目的:调查了解我国农村居民糖尿病患者痴呆的患病率。方法:选择湖南省慈利县50岁及以上农村居民中的糖尿病患者641例作为观察组,另外选择与其性别、年龄相匹配的非糖尿病患者641例作为对照组。采用入户调查问卷及简易精神状态检查量表(MMSE)进行认知功能的筛查,对MMSE低于划界分者由神经内科医师组成的专家组做进一步检查,并按照美国精神病学会精神障碍诊断与统计手册第4版(DSM-Ⅳ)标准进行痴呆的诊断。结果:(1)观察组完成调查624例,罹患痴呆33例,患病率5.28%(95%CI3.33%～7.82%);对照组完成调查619例,罹患痴呆14例,患病率2.26%(95%CI1.14%～4.01%。观察组痴呆患病率非常显著高于对照组(P<0.01)。(2)观察组50～59岁、60～69岁、70～79岁及80岁以上4个年龄段中痴呆的患病率分别为2.23%(5/224)、4.74%(11/232)、7.33%(8/109)、13.15%(10/76,趋势χ2=16.27,P<0.01);对照组相应年龄段痴呆患病率分别为1.35%(3/222)、1.70%(4/234)、3.57%(4/112)及4.10%(3/73,趋势χ2=8.37,P<0.05)。(3)观察组中男性和女性痴呆患病率分别为3.72%(9/242)和6.01%(24/399),男性和女性痴呆患病率比较,差异显著(P<0.05);对照组中男性和女性痴呆患病率分别为1.68%(5/238)和1.98(8/403),虽然女性痴呆患病率高于男性,但差异不显著(P>0.05)。结论:糖尿病患者痴呆的患病率非常显著高于非糖尿病患者,而且女性糖尿病患者痴呆的患病率显著高于男性糖尿病患者,且两组人群痴呆的患病率均随着年龄增大而升高。     

Phase 1 clinical study of 123I-FP-CIT, a new radioligand for evaluating dopamine transporter by SPECT (II): Tracer kinetics in the brain

The kinetics of 123I-FP-CIT in the brain for healthy subjects were studied. Twelve dynamic SPECT data sets (0- to 6-hr after an intravenous injection) from a Phase 1 clinical trial of 123I-FP-CIT were analyzed. Tracer concentrations in the striatum, midbrain, cerebellum and cerebral cortex were measured on the SPECT images co-registered with the corresponding MR images. High tracer accumulation was observed in the striatum, which peaked at 60 min post-injection, followed by slow elimination (3%/hr). The kinetics were similar both in the cerebellum and in the cerebral cortex, which peaked at 15 min post-injection, followed by rapid elimination. Tracer accumulation in the midbrain was higher than in the cerebellum and cerebral cortex. The striatal specific/nonspecific binding ratio ((striatal-occipital)/occipital concentration ratio) was stable at 3-hr post-injection and later at a value of 3, suggesting that the specific binding of 123I-FP-CIT could be evaluated from a single SPECT image at 3- to 6-hr post-injection. The specific/nonspecific binding ratio at 4-hr post-injection showed a negative correlation with aging (r = -0.70, p = 0.01), with a decrease rate of 11%/decade (95% confidence interval: 3%-19%/decade).     

Clinical usefulness of exercise/rest 99mTc-teboroxime SPECT imaging: results of a Japanese multi-center phase II study]

99mTc-Teboroxime [Chloro[tris(cyclohexyldioxime)methaneboronic acid] (99mTc)technetium], a perfusion agent for myocardial imaging, has a distinct advantage over 201Tl because of its very high myocardial extraction and is a 99mTc compound ideal for gamma camera imaging. This agent also demonstrates rapid myocardial washout, which allows completion of exercise and rest imaging studies in a short interval (to 1 hour). However, the rapid washout necessitates the completion of image acquisition very quickly after injection and therefore may require nonconventional SPECT imaging. In this Phase II study we evaluate the safety and efficacy of 99mTc-Teboroxime to detect coronary artery disease by exercise and rest SPECT imaging in 38 patients with prior myocardial infarction, 31 patients with angina pectoris, and 4 patients with non-coronary cardiac diseases. The 99mTc-Teboroxime dose used was 370-740 MBq in each study. The findings were compared with coronary angiography or 201Tl exercise and redistribution SPECT. No significant adverse reactions or laboratory abnormalities attributable to 99mTc-Teboroxime were observed. The quality of SPECT images was optimal in 62.5% of all patients. The relatively large population of suboptimal cases (37.5%) was attributed to the delay of the start and prolongation of the image acquisition time. In 85.7% of patients whose imaging was started within 5 minutes and completed within 11 minutes after injection, optimal quality was observed. Thus, 99mTc-Teboroxime SPECT requires the rapid completion of image acquisition after injection to achieve optimal image quality. Abnormalities of 99mTc-Teboroxime distribution were detected in 97.1% and 62.1% of patients with prior myocardial infarction or angina pectoris, respectively. The concordance with coronary angiography was 84.4% and 68.0%, and with 201Tl was 78.1% and 74.1%, respectively. Although standardization of the image protocol suitable for this agent is needed for the next study, these high correlations suggest the potential usefulness of 99mTc-Teboroxime SPECT imaging.     

Detection of post-exercise stunning by early gated SPECT myocardial perfusion imaging: Results from the IAEA multi-center study

Background

Transient post-ischemic LV dysfunction due to myocardial stunning in patients with coronary artery disease can be missed by conventional gated SPECT (GSPECT) acquisitions. The aim of this IAEA-sponsored multi-center study was to determine whether early post-exercise imaging is more likely to detect stunning than conventional without adversely affecting image quality or perfusion information.

Methods and Results

Patients undergoing exercise/rest GSPECT were enrolled in this international multicenter study. Post-exercise studies were acquired at 15 ± 5 minutes after radiotracer injection (Stress-1) and repeated at 60 ± 15 minutes (Stress-2). Rest studies (R) were acquired at 60 minutes post injection. A core laboratory quantitatively assessed perfusion pattern and LV blinded to the acquisition time. Ischemia was defined as summed stress score (SDS) ≥4, and stunning was defined as the difference between rest and post-stress LVEF (Δ-LVEF). In the 229 patients enrolled into the study, both image quality and perfusion information were similar between Stress-1 and Stress-2. Post-stress LVEF was associated with both ischemia and time of acquisition, with a significant correlation between SDS and Δ-LVEF, which was stronger at Stress-1 than Stress-2 in the ischemic compared to the non-ischemic population (r = 0.23 vs 0.08, P = 0.10).

Conclusions

Early post-exercise imaging is feasible, and can potentially improve the detection of post-ischemic stunning without compromising image quality and perfusion data