Perfusion Single Photon Emission Computed Tomography Research Articles

Clinical Usefulness of 99mTc-Hexamethyl Propylene Amine Oxime Perfusion Single Photon Emission Computed Tomography for Early Phase Multiple System Atrophy

Background: Clinical diagnosis of multiple system atrophy (MSA) relays on signs and symptoms that are often difficult to identify particularly at early stage. Indeed neuropathological studies have demonstrated that Parkinson variant of MSA (MSA-P) is the first cause of misdiagnosis in a cohort of patients presenting with parkinsonian features. But accurate diagnosis of these disorders is important for deciding on treatment, appropriate advice and prognosis since atypical parkinsonian disorders are characterized by poor response to dopaminergic treatment and more rapid disease progression. Therefore, we conducted this study to investigate difference of perfusion Single Photon Emission Computed Tomography (SPECT) in patients with the early phase of MSA-P using SPM program. Methods: We recruited consecutively 21 patients with MSA-P and 48 age-matched healthy controls. All subjects underwent Tc-99m HMPAO perfusion SPECT and this perfusion images were analyzed. Results: For MSA-P, only hypoperfusion was seen in the middle frontal gyrus of left frontal lobe, superior frontal gyrus of right frontal lobe, precentral gyrus of left frontal lobe, middle frontal gyrus of right frontal lobe and precentral gyrus of right frontal lobe with respect to healthy subjects. Conclusions: We cautiously assume that perfusion SPECT may offer significant advantages compared to other imaging techniques in the assessment of neuronal degeneration in MSA-P and may help the clinician in the diagnostic characterization of patients presenting with atypical parkinsonism. Received: May 16, 2014 Revision received: May 28, 2014 Accepted: May 28, 2014

Validation of automated quantification of myocardial perfusion single-photon emission computed tomography using Heart Score View in patients with known or suspected coronary artery disease.

Heart Score View (HSV) is a free software package for automated quantification of myocardial single photon emission computed tomography (SPECT) imaging using a standard Windows computer. We compared scoring results of myocardial perfusion among visual analysis, Quantitative Perfusion SPECT (QPS), and HSV in patients with known or suspected coronary artery disease.This study included 75 consecutive patients with known or suspected coronary artery disease who underwent adenosive stress-rest Tl-201 SPECT. Analysis of myocardial perfusion SPECT was performed on a standard 17-segment model visually and using QPS and HSV.There were 54 male and 21 female patients with a mean age of 70.5 ± 10.7 years. Thirteen patients (17%) had prior myocardial infarction. Summed stress score (SSS) and summed rest score (SRS) in the mid and basal areas were significantly higher on HSV than visual analysis or QPS. There was no significant difference in SDS in the whole area among the 3 methods. Similar results were found even in patients without prior myocardial infarction. Manual setting of the left ventricular cavity improved the correlations of SSS, SRS and SDS between HSV and the other methods.Our data suggested that HSV was comparable with visual analysis or QPS in scoring myocardial perfusion when manual setting of the left ventricular cavity is applied.

心筋SPECT 検査での多焦点ファンビームコリメータにおける画像再構成条件の最適化

The aim of this study was to optimize the reconstruction parameters for ordered subset conjugate gradient minimization (OSCGM) reconstruction using a multifocus fan beam collimator in myocardial perfusion single photon emission computed tomography (SPECT). We attempted to validate the following performance of OSCGM reconstruction parameters (iteration and subset). SPECT images were acquired using a dual-head gamma camera with IQ mode acquisition systems from a RH-2 cardiac phantom containing a 99m-Tc solution. The performance was evaluated using reconstruction parameters (product of subset and iteration: SI) with image contrast, LV volume [using quantitative perfusion SPECT (QPS)], root mean square uncertainty (RMSU), and normalized mean squared error (NMSE). The best results (contrast, uniformity, LV volume, and NMSE) were found for SI: 30. LV volume indicated the true volume for subset: 1 and iteration: 30, and LV volume was underestimated by 10% for iteration >20, and subset >1. The results of this myocardial perfusion SPECT study suggest the optimal OSCGM reconstruction parameter to be subset: 1 and iteration: 30 using a multifocus fan beam collimator.

Impaired Coronary Flow Reserve Is the Most Important Marker of Viable Myocardium in the Myocardial Segment-Based Analysis of Dual-Isotope Gated Myocardial Perfusion Single-Photon Emission Computed Tomography

ObjectiveThe aim of this study was to investigate the most robust predictor of myocardial viability among stress/rest reversibility (coronary flow reserve [CFR] impairment), 201Tl perfusion status at rest, 201Tl 24 hours redistribution and systolic wall thickening of 99mTc-methoxyisobutylisonitrile using a dual isotope gated myocardial perfusion single-photon emission computed tomography (SPECT) in patients with coronary artery disease (CAD) who were re-vascularized with a coronary artery bypass graft (CABG) surgery.Materials and MethodsA total of 39 patients with CAD was enrolled (34 men and 5 women), aged between 36 and 72 years (mean 58 ± 8 standard in years) who underwent both pre- and 3 months post-CABG myocardial SPECT. We analyzed 17 myocardial segments per patient. Perfusion status and wall motion were semi-quantitatively evaluated using a 4-point grading system. Viable myocardium was defined as dysfunctional myocardium which showed wall motion improvement after CABG.ResultsThe left ventricular ejection fraction (LVEF) significantly increased from 37.8 ± 9.0% to 45.5 ± 12.3% (p < 0.001) in 22 patients who had a pre-CABG LVEF lower than 50%. Among 590 myocardial segments in the re-vascularized area, 115 showed abnormal wall motion before CABG and 73.9% (85 of 115) had wall motion improvement after CABG. In the univariate analysis (n = 115 segments), stress/rest reversibility (p < 0.001) and 201Tl rest perfusion status (p = 0.024) were significant predictors of wall motion improvement. However, in multiple logistic regression analysis, stress/rest reversibility alone was a significant predictor for post-CABG wall motion improvement (p < 0.001).ConclusionStress/rest reversibility (impaired CFR) during dual-isotope gated myocardial perfusion SPECT was the single most important predictor of wall motion improvement after CABG.

Effect of detector blurring on apical region in myocardial perfusion SPECT imaging

One of the largest application fields of the Single Photon Emission Computed Tomography (SPECT) technology is parallel imaging based myocardial perfusion scintigraphy. Any image improvements resulting from the evaluation of the distortions and noise phenomena have significant diagnostic value in this field. Several distortion effects have been compensated inherently - non-uniform photon abortion and non-linear distant dependent spatial resolution (DDSR) effects of the imaging - by our developed novel 3D iterative reconstruction method. However, equivocal hypo-perfusion segment have been detected around the apical region of the myocardium systematically on both mathematical phantoms, physical phantoms, and in human studies. We concluded that the Partial Volume Effect (PVE) phenomenon may cause the distortion. The aim of the current research is to discover the impact of the 3D parallel projection based reconstruction parameters on the apical lesion effect.Several reconstruction setups with different parameter settings are executed using different mathematical phantoms to model the myocardium. The reconstructed images are compared with quantitative measures. The degree of apical lesion is decreased if a volume of 2563 with voxel sizes of 2mm was applied instead of a volume of 1283 with voxel sizes of 4mm. Higher resolution volumes caused reduced Partial Volume Effect. In addition, a lesser extent of detector blurring resulted in less apical lesion. Further investigations are planned to analyze relationship between reconstruction setups and apical lesion.

LV Dyssynchrony Assessed With Phase Analysis on Gated Myocardial Perfusion SPECT Can Predict Response to CRT in Patients With End-Stage Heart Failure.

Background:Cardiac resynchronization therapy (CRT) is an established treatment in patients with end-stage heart failure and wide QRS complex. However, about 30% of patients do not benefit from CRT (non-responder). Recent studies with tissue Doppler imaging yielded disappointing results in predicting CRT responders. Phase analysis was developed to allow assessment of LV dyssynchrony by gated single photon emission computed tomography (SPECT) myocardial perfusion imaging (GMPS).Objectives:The aim of present study was to investigate the role of quantitative GMPS-derived LV dyssynchrony data to predict CRT responder.Patients and Methods:Thirty eligible patients for CRT implantation underwent GMPS and echocardiography. Response to CRT was evaluated six months after the device implantation. Clinical response to CRT was defined as 50 meters increase in 6-minute walking test (6-MWT) distance. Echocardiographic response to CRT was defined as ≥ 15% decrease in left ventricular end-systolic volume (LVESV). The lead position was considered concordant if it was positioned at the area of latest mechanical activation, and discordant if located outside the area of latest mechanical activation.Results:Clinical response to CRT was observed in 74% of patients. However, only 57% of patients were responder according to the echo criteria. There were statistically significant differences between CRT responders and non-responders for GMPS-derived variables, including phased histogram bandwidth (PHB), phase SD (PSD), and Entropy. Moreover, a cutoff value of 112° for PHB with a sensitivity of 72% and specificity of 70%, a cutoff value of 21° for PSD with a sensitivity of 90% and specificity of 74%, and a cutoff of 52% for Entropy with a sensitivity of 90% and a specificity of 80% were considered to discriminate responders and non-responders. CRT response was more likely in patients with concordant LV lead position compared to those with discordant LV lead position.Conclusions:GMPS-derived LV dyssynchrony variables can predict response to CRT with good sensitivity and specificity.

Brain perfusion SPECT in limbic encephalitis associated with autoantibody against the glutamate receptor epsilon 2

The aim of this study was to elucidate the single-photon emission computed tomography (SPECT) pattern at the acute stage of disease in non-herpetic limbic encephalitis (NHLE) patients associated with the N-methyl-D-aspartate-type glutamate receptor epsilon 2 (GluR ϵ2) autoantibody using Z-score imaging system (eZIS) analyses. Brain magnetic resonance imaging (MRI) and brain perfusion SPECT using technetium-99 ethyl cysteinate dimer ((99m)Tc-ECD) were performed in eight patients with NHLE (5 men and 3 women; mean age 48.8±22 years) within 20days after clinical onset. All patients had various clinical limbic-associated symptoms and no evidence of herpes simplex infection or systemic malignancies. Two of eight patients showed abnormally hyperintense lesions on diffusion-weighted images and significant hyperperfusion in ipsilateral cerebral cortex on eZIS analysis, whereas other patients showed normal MRI findings and significant hypoperfusion in one or both sides of the limbic and paralimbic areas. We suggest that (99m)Tc-ECD SPECT study using eZIS analyses may be helpful to detect the neuronal dysfunction, particularly in NHLE patients without abnormal MRI findings.

Combination of blood flow asymmetry in the cerebral and cerebellar hemispheres on brain perfusion SPECT predicts 5-year outcome in patients with symptomatic unilateral major cerebral artery occlusion

Background and objective: Misery perfusion increases the risk of stroke recurrence in patients with symptomatic major cerebral artery occlusion. The ratio of brain perfusion contralateral-to-affected asymmetry in the cerebellar hemisphere to brain perfusion affected-to-contralateral asymmetry in the cerebral hemisphere (CblPR/CbrPR) indicates affected-to-contralateral asymmetry of oxygen extraction fraction (OEF) in the cerebral hemisphere. The purpose of the present study was to determine whether the CblPR/CbrPR on brain perfusion single-photon emission computed tomography (SPECT) predicts 5-year outcomes in patients with symptomatic unilateral occlusion of the middle cerebral artery (MCA) or internal carotid artery (ICA).Methods: Brain perfusion was assessed using N-isopropyl-p-[123I]-iodoamphetamine (123I-IMP) SPECT in 70 patients. A region of interest (ROI) was manually placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres, and the CblPR/CbrPR was calculated. All patients were prospectively followed for 5 years. The primary end points were stroke recurrence or death.Results: A total of 17 patients exhibited the primary end points, 11 of whom experienced subsequent ipsilateral strokes. Multivariate analysis revealed that only high CblPR/CbrPR was significantly associated with the development of the primary end point or subsequent ipsilateral strokes (95% confidential limits [CIs], 1·130–3·145; P = 0·0114 or 95% CIs, 2·558–5·140; P = 0·0045, respectively). The CblPR/CbrPR provided 65% (11/17) or 91% (10/11) sensitivity and 88% (47/53) or 88% (52/59) specificity in predicting the primary end point or subsequent ipsilateral strokes, respectively.Conclusions: The CblPR/CbrPR on brain perfusion SPECT predicts 5-year outcomes in patients with symptomatic unilateral occlusion of the MCA or ICA.

Early Diagnosis of Alzheimer's Disease and Parkinson's Disease Associated with Dementia Using Cerebral Perfusion SPECT

Background: Since patterns of cognitive dysfunction in mild Parkinson's disease associated with dementia (PDD) are similar to those in mild Alzheimer's disease (AD), it is difficult to accurately differentiate between these two types of dementia in their early phases using neuropsychological tests. The purpose of the current study was to investigate differences in cerebral perfusion patterns of patients with AD and PDD at the earliest stages using single photon emission computed tomography (SPECT). Methods: We consecutively recruited 31 patients with mild PDD, 32 patients with mild probable AD and 33 age-matched healthy subjects. All subjects underwent ^99mTc-hexamethylpropyleneamine oxime perfusion SPECT and completed general neuropsychological tests. Results: We found that both mild PDD and AD patients showed distinct hypoperfusion in frontal, parietal and temporal regions, compared with healthy subjects. More importantly, hypoperfusion in occipital and cerebellar regions was observed only in mild PDD. Conclusion: The observation of a significant decrease in cerebral perfusion in occipital and cerebellar regions in patients with mild PDD is likely useful to differentiate between PDD and AD at the earliest stages.

Effects of acquisition time and reconstruction algorithm on image quality, quantitative parameters, and clinical interpretation of myocardial perfusion imaging

BackgroundRecently introduced iterative reconstruction algorithms with resolution recovery (RR) and noise-reduction technology seem promising for reducing scan time or radiation dose without loss of image quality. However, the relative effects of reduced acquisition time and reconstruction software have not previously been reported. The aim of the present study was to investigate the influence of reduced acquisition time and reconstruction software on quantitative and qualitative myocardial perfusion single photon emission computed tomography (SPECT) parameters using full time (FT) and half time (HT) protocols and Evolution for Cardiac Software. MethodsWe studied 45 consecutive, non-selected patients referred for a clinically indicated routine 2-day stress/rest 99mTc-Sestamibi myocardial perfusion SPECT. All patients underwent an FT and an HT scan. Both FT and HT scans were processed according to our standard procedure with both ordered-subset expectation maximization (OSEM) + filtered back projection (FBP) reconstructions and a second reconstruction of HT scans was performed with the RR software producing three datasets for each patient for visual analysis (FT-OSEM, HT-OSEM, and HT-RR) and for quantitative analysis (FT-FBP, HT-FBP, and HT-RR). The datasets were analyzed using commercially available QGS/QPS software and read by two observers evaluating image quality and clinical interpretation. Image quality was assessed on a 10-cm visual analog scale score. ResultsHT imaging was associated with loss of image quality that was compensated for by RR reconstruction. HT imaging was also associated with increasing perfusion defect extents, an effect more pronounced using RR than FBP reconstruction. Compared to standard FT-FBP, HT-RR significantly reduced left ventricular volumes whereas HT-FBP increased end-systolic volume. HT imaging had no effect on measured left ventricular ejections fraction or measures of reversibility. Image interpretation found a higher level of concordance between FT-OSEM and HT-RR than between FT-OSEM and HT-OSEM without any observable systematic effects. ConclusionsUse of RR reconstruction algorithms compensates for loss of image quality associated with reduced scan time. Both HT acquisition and RR reconstruction algorithm had significant effects on motion and perfusion parameters obtained with standard software, but these effects were relatively small and probably of limited clinical importance. Although no systematic effects on image interpretation were observed, the influence on diagnostic accuracy remains to be determined.

Validation of automated quantification of nuclear cardiology in Japanese patients using total perfusion deficits: Comparison with visual assessment

BackgroundAutomated quantitative assessment based on a total perfusion deficit (TPD) has been recognized to be useful for detection of coronary artery disease (CAD). We, therefore, aimed to validate reproducibility of the automated quantification with the TPD on myocardial perfusion single photon emission computed tomography (SPECT) images in Japanese patients with history of stable CAD. MethodsPatients (n=47, age 67±10) underwent rest 201Tl and stress 99mTc-tetrofosmin myocardial perfusion SPECT on two separate occasions with the same protocol within 3–26 months. They had abnormal findings on the first SPECT imaging by visual analysis and had no changes in symptoms, cardiac medications, coronary risk factors, and electrocardiogram findings at the time of the second imaging. They had no intervening coronary revascularization and myocardial infarction between the first and second imaging. The TPD was automatically derived from SPECT images through quantitative perfusion SPECT software with the Japanese normal database. A visual summed stress score (SSS) was estimated with the 5-point visual scoring model for 20 segments of SPECT images by independent expert interpreters. Abnormal criteria for the stress TPD and SSS were defined as ≥5% and ≥4, respectively. ResultsThe stress TPD determined by the quantitative analysis well correlated between the first and second imaging (r=0.985) as well as the SSS by the visual analysis showed good correlation (r=0.978). The correlation coefficients were similar between the visual and quantitative analyses. Bland–Altman analyses indicated extremely good reproducibility in both assessments. ConclusionThe TPD is evidently a quantitative index having high reproducibility and the automated quantification with it provides comparable results to the visual assessment by experienced interpreters. The automated quantification with the TPD is highly significant for clinical assessment of CAD, and allows easily performing myocardial perfusion SPECT imaging without expert interpreters.

SPECT Myocardial Perfusion in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a rare hereditary small vessel disease. Although the symptoms are exclusively neurological, arteriopathy is generalized. We performed cardiac evaluation using myocardial perfusion single photon emission computed tomography (SPECT), dual-source 128-channel multidetector computed tomography (MDCT) angiogram, echocardiogram, and electrocardiogram (ECG) in a 46-year-old woman with CADASIL. No abnormal findings were observed on MDCT angiogram, echocardiogram, or ECG. However, SPECT demonstrated reversible perfusion defects in the left anterior descending artery territory. We suggest that myocardial perfusion SPECT is a valuable tool to identify risk from cardiovascular accident in CADASIL patients.

Acute Myocardial Infarction: Estimation of At-Risk and Salvaged Myocardium at Myocardial Perfusion SPECT 1 Month after Infarction

To estimate at-risk and salvaged myocardium by using gated single photon emission computed tomography (SPECT) myocardial perfusion imaging after acute myocardial infarction (AMI). The study was approved by the hospital's Ethical Committee on Clinical Trials (trial register number, PR(HG)36/2000), and all patients gave informed consent. Forty patients (mean age, 61.78 years; eight women) with a first AMI underwent two gated SPECT examinations--one before percutaneous coronary intervention (PCI) and one 4-5 weeks after PCI. Myocardium at risk was estimated by assessing the perfusion defect at the first gated SPECT examination, and salvaged myocardium was estimated by assessing the risk area minus necrosis at the second examination. Myocardium at risk was estimated by determining the discordance between the areas of left ventricular (LV) wall motion and perfusion at the second examination. Concordance between tests was analyzed by means of linear regression analysis, the Pearson correlation, the intraclass correlation coefficient, and Bland-Altman analysis. An improvement in perfusion, wall motion, wall thickening, and LV ejection fraction (P < .001) was observed at 1 month. At 1 month, the area with abnormal wall motion was greater than the area of altered perfusion (35.47 vs 23.1 cm(2); P = .007). The extent of myocardium at risk estimated from this discordance correlated well with myocardium at risk measured at the first gated SPECT examination and with salvaged myocardium between both studies (Pearson correlation: 0.78 and 0.6, respectively). Concordance for correct classification of patients with salvaged myocardium of 50% or greater was 83% (κ = 0.65). Myocardial perfusion gated SPECT performed 1 month after early PCI in a first AMI provides potentially useful information on at-risk and salvaged myocardium. http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.13122324/-/DC1.

12-Year outcome after normal myocardial perfusion SPECT in patients with known coronary artery disease

BackgroundPrevious studies have reported a favorable outcome of patients with normal single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI). The aim of this study was to assess the very long-term prognosis of patients with known coronary artery disease (CAD) and normal SPECT MPI results. MethodsThe population consisted of 266 patients with known CAD (defined as a healed myocardial infarction and/or a previous coronary revascularization), who underwent exercise bicycle or dobutamine-atropine stress SPECT MPI and had normal perfusion during stress and at rest. End points during follow-up were all-cause mortality, cardiac mortality, and nonfatal myocardial infarction. Univariate and multivariate analyses were performed to identify predictors of long-term outcome. ResultsFollow-up was completed in 261 (98%) patients. During a median follow-up of 12 years, 94 (36%) patients died, of which 26 (10%) died due to cardiac causes, and 15 (6%) had a nonfatal myocardial infarction. The annualized mortality rate was 3.1%, annualized cardiac mortality rate was 0.9%, and the annualized event rate for cardiac death and/or nonfatal infarction was 1.2%. Independent predictors of total mortality were age, diabetes mellitus, and rate-pressure product at peak stress. Independent predictors of cardiac mortality were age, male gender, and rate-pressure product at peak stress. ConclusionPatients with known CAD and a normal SPECT MPI study have a favorable long-term prognosis. Clinical and stress test variables can be used to identify patients with a higher risk status.

Low-dose single acquisition rest 99mTc/stress 201Tl myocardial perfusion SPECT protocol: phantom studies and clinical validation

We developed and tested a single acquisition rest (99m)Tc-sestamibi/stress (201)Tl dual isotope protocol (SDI) with the intention of improving the clinical workflow and patient comfort of myocardial perfusion single photon emission computed tomography (SPECT). The technical feasibility of SDI was evaluated by a series of anthropomorphic phantom studies on a standard SPECT camera. The attenuation map was created by a moving transmission line source. Iterative reconstruction including attenuation correction, resolution recovery and Monte Carlo simulation of scatter was used for simultaneous reconstruction of dual tracer distribution. For clinical evaluation, patient studies were compared to stress (99m)Tc and rest (99m)Tc reference images acquired in a 2-day protocol. Clinical follow-up examinations like coronary angiography (CAG) and fractional flow reserve (FFR) were included in the assessment if available. Phantom studies demonstrated the technical feasibility of SDI. Artificial lesions inserted in the phantom mimicking ischaemia could be clearly identified. In 51/53 patients, the image quality was adequate for clinical evaluation. For the remaining two obese patients with body mass index > 32 the injected (201)Tl dose of 74 MBq was insufficient for clinical assessment. In answer to this the (201)Tl dose was adapted for obese patients in the rest of the study. In 31 patients, SDI and (99m)Tc reference images resulted in equivalent clinical assessment. Significant differences were found in 20 patients. In 18 of these 20 patients additional examinations were available. In 15 patients the diagnosis based on the SDI images was confirmed by the results of CAG or FFR. In these patients the SDI images were more accurate than the (99m)Tc reference study. In three patients minor ischaemic lesions were detected by SDI but were not confirmed by CAG. In one of these cases this was probably caused by pronounced apical thinning. For two patients no relevant clinical follow-up information was available for evaluation. The proposed SDI protocol has the potential to improve clinical workflow and patient comfort and suggests improved accuracy as demonstrated in the clinical feasibility study.

Correlation of Cognition and SPECT Perfusion: Easy Z Score and SPM Analysis of a Pilot Sample with Cerebral Small Vessel Disease

Background/Aims: To associate neuropsychology test performance with perfusion on single-photon emission computed tomography (SPECT) among 12 patients with cerebral small vessel disease. Methods: The easy Z score imaging system (eZIS) was used to compare patient images to those of normal controls. Scores from neuropsychological tests commonly used to screen for dementia were associated with SPECT resting perfusion image values using the statistical parametric mapping (SPM) program. Results: Immediate Memory and Delayed Memory index scores, as well as memory subtests of the Repeatable Battery for Assessment of Neuropsychological Status showed cluster- and voxelwise positive correlations with hypoperfusion in frontal, temporal and cerebellar regions. Negative correlations, primarily in frontal regions, were interpreted as compensatory hyperperfusion. Conclusion: eZIS and SPM analyses of SPECT images showed perfusion correlations with neuropsychological tests with small vessel disease.

Long-Term Follow-up Assessment After the Arterial Switch Operation for Correction of Dextro-Transposition of the Great Arteries by Means of Exercise Myocardial Perfusion-Gated SPECT

The arterial switch operation (ASO) is the preferred technique for correcting transposition of the great arteries, but translocation and reimplantation of the coronary arteries can produce myocardial ischemia. This report aims to describe the authors' experience with exercise single-photon emission computed tomography (SPECT) used to evaluate myocardial perfusion. Exercise-rest gated-myocardial perfusion SPECT was performed for 69 patients (49 boys; median age, 9years; 5th percentile [6.4years] to 95th percentile [15.6years]), 64 of whom were asymptomatic 9.98±3.20years after ASO. During exercise testing, the patients reached 9.85±3.05 metabolic equivalents (METs) and a median heart rate of 160beats per minute (bpm), 5th percentile (106bpm) to 95th percentile (196bpm). Whereas 61 patients (88.41%) had normal myocardial perfusion, 2 patients (2.9%) had reversible defects, and 6 patients (8.7%) had fixed defects. All the patients with perioperative ischemic complications (4/4, 100%) had myocardial perfusion defects, whereas four patients (4/65, 6.15%) without ischemic complications had abnormal perfusion (p=0.0005). Age at the time of surgery did not differ significantly (p=0.234) between the patients with perfusion defects and those with normal study results. No significant difference was observed between the patients who had an A coronary pattern (left coronary artery originating from the left sinus and the right coronary artery originating from the right sinus, n=47) and those who had a non-A coronary pattern (n=22) (p=1). The high rate for normality of exercise myocardial perfusion in our study suggests that myocardial perfusion gated-SPECT should be reserved for patients who have experienced perioperative ischemic complications or those with symptoms, at least during the first 10years after the surgery.

Correlation of brain structural and functional changes in amnestic mild cognitive impairment and mild Alzheimer's disease: A voxel-by-voxel analysis in a single cohort of patients in Brazil

Amnestic mild cognitive impairment (aMCI) and Alzheimer's disease (AD) are believed to be a continuum of the same process, in which aMCI is a symptomatic pre-dementia stage. There is a growing need to early diagnosis and neuroimaging methods may help it. Nevertheless, there is a relative lack of studies which correlate findings in magnetic resonance imaging (MRI) and functional imaging such as single photon emission computed tomography (SPECT) and positron emission tomography (PET) in the same cohort of patients. The objective of this study was to compare the findings of these three methods in mild AD, aMCI and in normal elderly volunteers (control group - CG). We prospectively evaluated 94 subjects that were distributed after clinical and neuropsychological evaluation as follows: 34 in the mild AD group (CDR=1.0); 30 in the aMCI group (CDR = 0.5); and 30 in the CG (CDR= 0). All patients were submitted to MRI for volumetric based morphometry (VBM), brain perfusion SPECT with ECD- 99m Tc and glucose metabolism PET with 18 F-fluordeoxyglucose (FDG-PET). Results were quantified and compared in a voxel by voxel basis with the software SPM8. Patient clinical data are detailed in Table 1. In relation to CG, AD showed volumetric reductions in both temporal lobes (parahippocampal gyrus / amigdala and middle temporal gyrus), reduction in glucose metabolism bilaterally in parahippocampal uncus, temporoparietal regions and posterior cingulate. SPECT disclosed reduced perfusion in left parahippocampal gyrus, transverse temporal gyrus and right precuneus. The aMCI group showed only discrete changes including volume reduction in the left superior temporal gyrus, glucose hypometabolism in the right precuneus and flow reduction in the left superior temporal gyrus and transverse temporal gyrus. The findings of MRI, FDG-PET and SPECT were in part concordant, mostly in AD. Those have been previously reported and correspond to some of the imaging hallmarks of mild AD. PET showed higher extension of involvement in comparison to both MRI and SPECT, depicting a poor association between volumetric and functional abnormalities in AD. It was not possible to see a perfect concordance among the three technologies in aMCI, findings in contrast with other reports in the literature.

Detection of misery perfusion in the cerebral hemisphere with chronic unilateral major cerebral artery steno-occlusive disease using crossed cerebellar hypoperfusion: comparison of brain SPECT and PET imaging

PurposeIn patients with unilateral internal carotid or middle cerebral artery (ICA or MCA) occlusive disease, the degree of crossed cerebellar hypoperfusion that is evident within a few months after the onset of stroke may reflect cerebral metabolic rate of oxygen in the affected cerebral hemisphere relative to that in the contralateral cerebral hemisphere. The aim of the present study was to determine whether the ratio of blood flow asymmetry in the cerebellar hemisphere to blood flow asymmetry in the cerebral hemisphere on positron emission tomography (PET) and single photon emission computed tomography (SPECT) correlates with oxygen extraction fraction (OEF) asymmetry in the cerebral hemisphere on PET in patients with chronic unilateral ICA or MCA occlusive disease and whether this blood flow ratio on SPECT detects misery perfusion in the affected cerebral hemisphere in such patients.MethodsBrain blood flow and OEF were assessed using 15O-PET and N-isopropyl-p-[123I]iodoamphetamine (123I-IMP) SPECT, respectively. All images were anatomically standardized using SPM2. A region of interest (ROI) was automatically placed in the bilateral MCA territories and in the bilateral cerebellar hemispheres using a three-dimensional stereotaxic ROI template, and affected-to-contralateral asymmetry in the MCA territory or contralateral-to-affected asymmetry in the cerebellar hemisphere was calculated. Sixty-three patients with reduced blood flow in the affected cerebral hemisphere on 123I-IMP SPECT were enrolled in this study.ResultsA significant correlation was observed between MCA ROI asymmetry of PET OEF and the ratio of cerebellar hemisphere asymmetry of blood flow to MCA ROI asymmetry of blood flow on PET (r = 0.381, p = 0.0019) or SPECT (r = 0.459, p = 0.0001). The correlation coefficient was higher when reanalyzed in a subgroup of 43 patients undergoing a PET study within 3 months after the last ischemic event (r = 0.541, p = 0.0001 for PET; r = 0.609, p < 0.0001 for SPECT). The blood flow ratio on brain perfusion SPECT in all patients provided 100 % sensitivity and 58 % specificity, with 43 % positive and 100 % negative predictive values for detecting abnormally elevated MCA ROI asymmetry of PET OEF.ConclusionThe ratio of blood flow asymmetry in the cerebellar hemisphere to blood flow asymmetry in the cerebral hemisphere on PET and SPECT correlates with PET OEF asymmetry in the cerebral hemisphere, and this blood flow ratio on SPECT detects misery perfusion in the affected cerebral hemisphere.

Diagnostic value of automated quantification of nuclear cardiology in Japanese patients with single vessel coronary artery disease: Comparison between Japanese and American normal databases

BackgroundThe Japanese diagnostic assessment of nuclear cardiology has usually been based on semi-quantitative visual analyses but not on automated quantification with a total perfusion deficit (TPD). We, therefore, aimed to determine whether automated TPD quantification is useful to detect coronary artery disease (CAD) in Japanese patients in comparison with conventional visual segmental analysis, and to compare results from the automated assessment between the Japanese and American normal databases (NDBs). MethodsPatients with suspected CAD underwent rest 201Tl and stress 99mTc-tetrofosmin myocardial perfusion single photon emission computed tomography (SPECT) and coronary angiography within three months. The TPD was automatically derived from the SPECT image through quantitative perfusion SPECT software with the Japanese and American NDBs. The visual summed stress scores (SSS) were estimated with the 5-point visual scoring model for 20 segments of SPECT images. An abnormal criteria for the stress TPD and SSS were defined as ≥5% and ≥4, respectively. ResultsDetection sensitivity of CAD was 87% with the stress TPD score derived from the Japanese NDB and 85% with the SSS in visual analysis. In contrast, the detection sensitivity with the stress TPD score derived from the American NDB was 75%, which was significantly lower than that with the Japanese TPD (p=0.0004). Specificity of the automated Japanese TPD assessment was similar to that of the visual SSS assessment (87% vs. 80%). Thus, sensitivity and specificity of the automated quantitative assessment based on the TPD scores derived from the Japanese NDB were consistent with that of visual quantification based on the segmental defect scores. ConclusionThe automated quantitative assessment with the Japanese NDB is useful for the detection of CAD when experts in visual interpretation of a myocardial perfusion SPECT image were absent in a clinical setting.