Myocardial Perfusion Studies Research Articles

Hemorrhagic Tamponade as Initial Manifestation of Systemic Lupus with Subsequent Refractory and Progressive Lupus Myocarditis Resulting in Cardiomyopathy and Mitral Regurgitation

Systemic lupus erythematosus (SLE) is a heterogeneous autoimmune disease with a wide range of clinical and serological manifestations. Cardiac disease among patients with SLE is common and can involve the pericardium, myocardium, valves, conduction system, and coronary arteries. We are reporting a case of SLE in a young woman that is unique is unique in that initial symptoms consisted of pericarditis and hemorrhagic tamponade which remained progressive and resistant to aggressive immunosuppressive treatment and led to severe cardiomyopathy (ejection fraction of 25%) and severe (+4) mitral regurgitation. Her immunosuppressive treatment included hydroxychloroquine, high-dose steroids, intravenous immunoglobulins, azathioprine, and mycophenolate mofetil. Her disease progression was felt to be due to underlying uncontrolled SLE because the complement levels remained persistently low throughout the entire course and PET Myocardial Perfusion and Viability study showed stable persistent active inflammation. Eventually, she was treated with cyclophosphamide which led to improvement in ejection fraction to 55% with only mild mitral regurgitation.

Effective Dose in Nuclear Medicine Studies and SPECT/CT: Dosimetry Survey Across Quebec Province.

The aims of the current study were to draw a portrait of the delivered dose in selected nuclear medicine studies in Québec province and to assess the degree of change between an earlier survey performed in 2010 and a later survey performed in 2014. Methods: Each surveyed nuclear medicine department had to complete 2 forms: the first, about the administered activity in selected nuclear medicine studies, and the second, about the CT parameters used in SPECT/CT imaging, if available. The administered activities were converted into effective doses using the most recent conversion factors. Diagnostic reference levels were computed for each imaging procedure to obtain a benchmark for comparison. Results: The distributions of administered activity in various nuclear medicine studies, along with the corresponding distribution of the effective doses, were determined. Excluding 131I for thyroid studies, 67Ga-citrate for infectious workups, and combined stress and rest myocardial perfusion studies, the remainder of the 99mTc-based studies delivered average effective doses clustered below 10 mSv. Between the 2010 survey and the 2014 survey, there was a statistically significant decrease in delivered dose from 18.3 to 14.5 mSv. 67Ga-citrate studies for infectious workups also showed a significant decrease in delivered dose from 31.0 to 26.2 mSv. The standardized CT portion of SPECT/CT studies yielded a mean effective dose 14 times lower than the radiopharmaceutical portion of the study. Conclusion: Between 2010 and 2014, there was a significant decrease in the delivered effective dose in myocardial perfusion and 67Ga-citrate studies. The CT portions of the surveyed SPECT/CT studies contributed a relatively small fraction of the total delivered effective dose.

Noninvasive Nuclear SPECT Myocardial Blood Flow Quantitation to Guide Management for Coronary Artery Disease.

Recently, myocardial blood flow quantitation with dynamic SPECT has been validated to enhance the detection of multivessel coronary artery disease (CAD) and conclude equivocal SPECT myocardial perfusion study. This advance opened an important clinical application to utilize the tool in guiding CAD management for area where myocardial perfusion tracers for PET are unavailable or unaffordable. We present a clinical patient with ongoing recursive angina who underwent multiple nuclear stress tests for a sequence of CAD evaluation in 26 months and demonstrated that SPECT myocardial blood flow quantitation properly guided CAD management to warrant patient outcome.

Reduced-time myocardial perfusion study processed with "Myovation Evolution" - assessment of diagnostic efficacy.

While assessing images using standard segmental method, we felt that some defects were either underscored or missed. So this work is intended to compare results of low count myocardial perfusion studies (MPS) processed with "Myovation Evolution", applying complete evaluation of all available slices, with full count studies and assess impact of reduction of counts on diagnostic efficacy of the study. A retrospective study was conducted in a group of 95 patients (56 males, age 62 ± 9 years, BMI 28 ± 4) with known or suspected CAD, without clinical history or any signs of a previous myocardial infarction. All patients underwent coronary angiography (CA) within 3 months of MPS. CA was used as a reference method for diagnostic performance of MPS. Patients underwent a stress/rest 2-day MPS. Both studies were performed twice, with normal (25 s) and shortened (13 s) time/projection. Studies were processed using Myovation protocol (OSEM, 2 iterations, 10 subsets) for full time (FT) studies and a Myovation Evolution protocol for half time (HT) studies (OSEM, 12 iterations, 10 subsets, Resolution Recovery). Reconstructed images, with and without attenuation correction (AC), were evaluated by 2 experienced nuclear medicine specialists (a consensus) visually, taking into account all available slices, in a 5-grade scale (normal, probably normal, equivocal, probably abnormal and abnormal). Study results were additionally dichotomized as normal or abnormal. Perfusion defects were assigned to coronary arteries. An exact agreement between FT and HT study assessment, without AC, amounted to 66%, with AC it grew to 79%, p = 0.05. In studies without AC 10 perfusion defects were found only in HT studies in RCA area in male patients. A higher percentage of studies with perfusion defects in RCA area visible only in HT studies was found among discordant (7/25, 28%) than concordant results (3/70, 4%), p = 0.003. AC reduced this difference. HT study provided lower accuracy in detection of CAD than FT study (58% vs. 68%, p = 0.034). AC reduced this difference considerably. Dichotomized assessment agreed in 81% of studies without AC and in 87% with AC. Myovation Evolution protocol requires application of AC otherwise perfusion defects in RCA area in male patients are falsely detected. Shortened studies reconstructed with "Myovation Evolution" package without AC reveal a tendency toward reduction of accuracy of the study in detection of CAD. AC makes up for this reduction.

The prognostic signifi cance of normal technetium-99m MIBI myocardial perfusion spect imaging over a four-year follow-up period

normal Tc-99m MIBI myocardial perfusion study has previously been shown to indicate a benign prognosis. Our aim was to determine the longer term prognosis of a normal study in our patient population. Methods: A retrospective evaluation of 209 patients with a normal Tc-99m MIBI study was performed. Follow-up data was obtained in 157 patients, with complete follow-up in 121 (mean follow-up period of 56 months). In 36 patients only partial follow-up was possible (32 months follow-up). No follow-up data, except for the possible registration of deaths, could be obtained in 52. Patients were evaluated for the occurrence of primary or secondary cardiac events. Results: The study group had a moderate pre-test probability for coronary artery disease (48 + 30.7%). Two possible cardiac deaths occurred (cardiac death rate of 0.95%). No primary events occurred in the group with complete follow-up, but 6 secondary events were recorded (cardiac event rate of 4.9%). No primary or secondary events occurred in the partial follow-up group during the follow-up period. The incidence of secondary or non-fatal primary events in this group for the period after they were lost to follow-up or in the group with no follow-up could not be ascertained. There was, however, no statistically significant difference between these groups regarding age, pre-test probability and exercise parameters. Conclusion: Similar to the findings with Tl-201, our study indicates a favourable longer term prognosis after a normal Tc-99m MIBI study.

Prognostic value of the cadmium-zinc-telluride camera: A comparison with a conventional (Anger) camera

BackgroundNew multipinhole cadmium-zinc-telluride (CZT) cameras allow for faster imaging and lower radiation doses for single photon emission computed tomography (SPECT) studies, but assessment of prognostic ability is necessary. Methods and ResultsWe collected data from all myocardial SPECT perfusion studies performed over 15 months at our institution, using either a CZT or conventional Anger camera. A Cox proportional hazards model was used to assess the relationship between camera type, imaging results, and either death or myocardial infarction (MI). Clinical variables including age, sex, body mass index (BMI), and historical risk factors were used for population description and model adjustments. We had 2,088 patients with a total of 69 deaths and 65 MIs (122 events altogether). A 3% increase in DDB (difference defect burden) represented a 12% increase in the risk of death or MI, whereas a 3% increase in rest defect burden or stress defect burden represented an 8% increase; these risks were the same for both cameras (P > .24, interaction tests). ConclusionsThe CZT camera has similar prognostic values for death and MI to conventional Anger cameras. This suggests that it may successfully be used to decrease patient dose.

Recent Advances in Nuclear Cardiology.

Nuclear cardiology is one of the major fields of nuclear medicine practice. Myocardial perfusion studies using single-photon emission computed tomography (SPECT) have played a crucial role in the management of coronary artery diseases. Positron emission tomography (PET) has also been considered an important tool for the assessment of myocardial viability and perfusion. However, the recent development of computed tomography (CT)/magnetic resonance imaging (MRI) technologies and growing concerns about the radiation exposure of patients remain serious challenges for nuclear cardiology. In response to these challenges, remarkable achievements and improvements are currently in progress in the field of myocardial perfusion imaging regarding the applicable software and hardware. Additionally, myocardial perfusion positron emission tomography (PET) is receiving increasing attention owing to its unique capability of absolute myocardial blood flow estimation. An F-18-labeled perfusion agent for PET is under clinical trial with promising interim results. The applications of F-18 fluorodeoxyglucose (FDG) and F-18 sodium fluoride (NaF) to cardiovascular diseases have revealed details on the basic pathophysiology of ischemic heart diseases. PET/MRI seems to be particularly promising for nuclear cardiology in the future. Restrictive diseases, such as cardiac sarcoidosis and amyloidosis, are effectively evaluated using a variety of nuclear imaging tools. Considering these advances, the current challenges of nuclear cardiology will become opportunities if more collaborative efforts are devoted to this exciting field of nuclear medicine.

Abstract 324: Ankle Brachial Index as a Predictor for Abnormal Cardiovascular Stress Test and Cardiovascular Outcomes

Background: The combination of ankle brachial index (ABI) and other risk stratification tools has been evaluated previously. However baseline ABI in patients admitted for chest pain prior to stress testing to predict increased probability of abnormal stress test and MACE (major cardiovascular adverse events) has not been studied. Methods: Patients (n= 342) admitted for chest pain with normal or unchanged electrocardiogram and negative troponin T who were referred for myocardial perfusion study were enrolled in this prospective observational study and followed for one year. The first part of the study was to assess if an abnormal ABI increases the probability of an abnormal stress test and the second part was to measure one-year outcome for MACE (Angina, MI, CHF, TIA/Stroke and deaths) based on their stress test and ABI results. Multivariable logistic regression modeling is used to interpret the data. Results: In our study population 83% of the patients had Framingham risk score less than 20. Twenty-nine percent of the patients with normal ABI and 40% of the patients with abnormal ABI had abnormal stress test. The difference is statistically insignificant. After adjusting for different variables abnormal ABI was found to have stronger correlation with MACE (Odds ratio 2.9, p 0.01, CI 1.2 - 6.7) as compared to abnormal stress test (Odds ratio 0.92, p 0.84 CI 0.3 - 2.1). Conclusion: In our study cohort an abnormal ABI, irrespective of the stress test results, was an independent predicator of MACE at one year. We can conclude that there is very weak temporal relationship between abnormal ABI and abnormal stress test in low risk population and asymptomatic peripheral vascular disease is a strong independent predictor of MACE, even in this low risk population. We can also conclude that ABI during stress testing can be used for risk stratification. Future studies may need more power in this low risk population.

50-letni mężczyzna z nawracającymi zawałami bez uniesienia odcinka ST i granicznymi zmianami w koronarografii — znaczenie diagnostyki czynnościowej

Dynamic development of invasive cardiology techniques significantly improved diagnostic and therapeutic abilities for patients with coronary artery disease. Functional assessment of coronary artery stenosis by fractional flow reserve (FFR) measurement or myocardial perfusion studies, such as single photon emission computed tomography (SPECT), allow detailed characterization of angiographically borderline atherosclerotic lesions in coronary arteries and guidance of therapeutic strategy. The authors presented a case of a 50-year old male hospitalized repeatedly due to non-ST segment elevation myocardial infarctions (NSTEMI). Combined functional assessment allowed correct diagnosis and optimal treatment.

Quantitative outcome of registration methods for correcting cardiac drift in cardiac PET/CT imaging.

Myocardial perfusion studies suffer from artifacts caused by misalignment of the transmission and emission data due to the influences of voluntary and involuntary patient motion. Regardless of G68e or respiratory‐averaged CT based attenuation correction and good patient cooperation, approximately 21% of perfusion studies exhibit artifacts arising from misalignment that cannot be corrected by manipulating the attenuation acquisition protocol. This misalignment, termed cardiac drift, is caused by slow‐moving abdominal cavity contents that reposition the heart in the thorax and appear as myocardial uptake overlying the left CT lung in fused PET/CT images. This study evaluates three postimaging registration techniques to correct PET/CT misalignment by altering the transmission map to match myocardial uptake. Simulated misalignment studies were performed with a cardiac torso phantom filled with [F18]FDG at 10:1 myocardium/background. An air‐filled saline bag affixed to the medial left lung surface served as a distensible lung. An initial CT acquisition was followed by successive PET acquisitions consisting of small displacements of the cardiac insert into the left lung. Phantom transmission scans were aligned to the myocardial uptake in the emission scans by applying 1) full rigid‐body translations and rotations, 2) rigid‐body restricted to medial / lateral and superior / inferior translation, or 3) an emission‐driven method that adds myocardial tissue to the transmission scan. These methods were also applied to 10 low‐likelihood coronary artery disease (CAD) patients showing signs of cardiac drift. Full rigid‐body registration showed significant over‐correction (p<0.004) of activity concentrations in the artifact areas of the phantom data due the relocation of highly attenuating structures (i.e., spine). Inaccurate regional activity distributions were also observed as streaks extending from the spine and these results were replicated in the patient population. There was no significant difference between the true phantom activity concentration after correction with the emission‐driven method. Misalignment corrected with the rigid‐body registration results in an increase in activity concentration but fails to accurately recover the true concentration. These data suggest that a nonlinear image registration approach such as an emission‐driven method results in a more uniform activity distribution throughout the myocardium, and is more appropriate for addressing the cardiac drift misalignment problem.PACS number(s): 87.57.uk, 87.57.Q, 87.57.nj, 87.57.C, 87.19.Hh

Role of PET-CT in the assessment of myocardial viability in patients with left ventricular dysfunction

AimRole of PET-CT in assessment of myocardial viability in patients with LV dysfunction. MethodsThis prospective study included 120 patients with LV dysfunction who underwent 99mTechnetium-Sestamibi myocardial perfusion SPECT-CT and 18FFDG cardiac PET-CT. They also underwent serial echocardiography and coronary angiography along with myocardial perfusion and FDG PET study. ResultsThirty-three patients had single vessel disease, 48 had triple vessel disease, and rest had double vessel disease. Among 786 segments, matched defects were seen in 432 (55%) and mismatched defects in 354 (45%) segments. 78 patients were surgically managed, and 42 were medically managed. The change in LVEF after surgical management was statistically significant compared to medical management. ConclusionViability assessment should be performed in patients who present after 12h of acute myocardial infarction or with LV dysfunction due to ischemic heart disease to decide upon appropriate surgical management.

Use of T2 maps for rapid prediction of stress effectiveness before the injection of contrast in myocardial perfusion studies at 3.0T

Use of T2 maps for rapid prediction of stress effectiveness before the injection of contrast in myocardial perfusion studies at 3.0T

Regadenoson in Myocardial Perfusion Study - First Institutional Experiences in Bosnia and Herzegovina.

Introduction:Myocardial perfusion imaging (MPI) is widely used in the evaluation of known and suspected coronary artery disease (CAD). Imaging of heart in stress and rest enables the comparison of myocardial uptake of radiotracer in proportion to the needs and coronary flow, which is used for detection of perfusion defects. Exercise stress and pharmacologic agents are used for the stressing purpose. Novel pharmacologic stressor regadenoson is A2A selective adenosine agonist, which selectively binds to the adenosine receptors in coronary arteries causing coronary dilatation.Materials and methods:We analyzed 50 myocardial perfusion studies performed with regadenoson as a pharmacologic agent that was injected before Tc99m-sestamibi in stress imaging. Stress and rest sets of images were evaluated for relative uptake of Tc99m-sestamibi in order to detect and characterize perfusion defects. After the injection of regadenoson, hemodynamic parameters and potential side-effects were closely monitored. Side-effects were stratified per severity as mild, moderate and severe. Studies were read by nuclear medicine physicians using quantitative perfusion SPECT software. Additional diagnostic information such as wall motion and wall thickening were provided by gating.Results:Thirty-three patients (66%) experienced one or more side-effects upon the administration of regadenoson, most commonly warmth and chest discomfort. In all patients but one (98%), the symptoms were mild, of short duration and self-limiting. Out of all side-effects registered, 44 (96%) were mild, and 2 (4%) were moderate. Two moderate side-effects developed in one patient with a prior history of asthma, and included shortness of breath and cough. Heart rate changed by 16 +- 31 bpm. Highest increase in blood pressure was 30 mm Hg for systolic, and 10 mm Hg for diastolic. One case of significant decrease in blood pressure was noted from the hypertensive basal values, 50 mm for systolic, and 30 mm Hg for diastolic. ST segment depression of up to 1 mm occurred in 4 cases (8%), and T-wave changes in 3 cases (6%). No conduction abnormalities, significant hypotension, symptomatic bradycardia or cardiac arrest ocurred.Conclusion:Our first institutional experiences proved regadenoson as A2A selective adenosine agonist as a pharmacologic stressor to be safe, tolerable and easily used. Its safety profile enabled the study to be performed in patients with respiratory disease also.

Evaluating the Role of Routine Prone Acquisition on Visual Evaluation of SPECT Images.

Attenuation artifacts reduce our ability to evaluate perfusion of affected myocardial segments. The aim of this study was to evaluate the impact of routine prone-position image evaluation within a stepwise visual interpretation of myocardial perfusion studies. We have included 279 consecutive patients who were referred for evaluation of myocardial ischemia. All patients underwent routine electrocardiogram-gated supine SPECT imaging and non-electrocardiogram-gated prone-position SPECT imaging. Three nuclear medicine physicians interpreted the images in the following order: polar maps, supine images, raw images, motion-frozen gated images, and prone images, using a scale of 0-4. Segments with perfusion abnormalities were noted. All physicians reported lower proportions of equivocal evaluations after evaluating prone images (18.3% vs. 4.7%, 19% vs. 11.1%, and 12.2% vs. 6.1%, P < 0.0001, P = 0.0077, and P = 0.0125, respectively). At the prone stage, normalcy rates were 89%, 87%, and 91%. Two physicians had significantly increased normalcy rates at the prone stage (72%-89%, P = 0.039, and 66%-87%, P = 0.006). At the prone stage, a decision reversal to normal or probably normal was observed in 40% (29/72), 33% (17/51), and 43% (21/48). In men, apical, mid, and basal inferior walls and in women apical and mid parts of anterior walls were more likely to be attributed to attenuation. The 2 steps that increased normalcy rates for interpreters were the review of raw images and of prone images. Routine prone imaging increases interpretive certainty and interobserver agreement and changes the final evaluation in a substantial number of patients and significantly decreases the number of equivocal evaluations.

Abstract 13754: Scar Burden and Left Ventricular Dyssynchrony on Myocardial Perfusion Imaging as Predictors of Antitachycardia Pacing Responsiveness in the Treatment of Ventricular Tachycardia

Background: Antitachycardia pacing (ATP) is the primary treatment for sustained ventricular tachycardia (VT), resulting in a reduction in ICD shocks. Patients who fail ATP have increased mortality compared to ATP responders. Myocardial scarring by cMR and left ventricular dysynchrony (LVD) by nuclear imaging are associated with a higher risk for VT. We hypothesized that scar and dyssynchrony can predict response to ATP. Methods: We identified 119 patients with sustained VT from 2008-2012, who received ICD therapy with preprogrammed ATP delivery and had a single photon emission computed tomography (SPECT) myocardial perfusion study. Semi-quantitative visual scoring with a 17-segment model was used and the summed stress, rest and difference scores were calculated to measure abnormal myocardium, scar and ischemia. LVD was measured in gated studies (n=59), using the established phase analysis (PA) methodology. Phase standard deviation (PSD) and histogram bandwidth (HBW) were compared between groups using chi-square analysis. Results: Of 119 patients (105 men, mean age: 75.8±18.2y), 82 (68%) had successful ATP. Normal myocardial perfusion was more commonly found in ATP-responders (10.5% vs. 19.8%, p=0.29). There was no difference in the presence of ischemia between the two groups. Phase SD (13.5±6.2 vs. 9.0±5.4, p=0.009) and HBW (54.5±27.1 vs. 37.9±25.2, p = 0.03) were significantly higher among ATP responders. In both a univariate and multivariate logistic regression analysis phase SD (OR, 95% CI: 1.85, 1.09-3.15, p=0.02) was an independent predictor of ATP success. Conclusions: LV dyssynchrony but not scar burden was associated with ATP responsiveness. These results are hypothesis generating for a role of LV dyssynchrony in the prediction of ATP responsiveness.

Anomalous right coronary artery originating from the mid left anterior descending artery

A 68-year-old male with a history of hypertension and hypercholesterolemia presented with recurrent episodes of chest discomfort. A 12-lead ECG and an echocardiogram were normal. A myocardial perfusion study could not rule out ischemia in the inferior wall. At coronary angiography using the transradial approach, the right coronary artery (RCA) could not be visualized. Angiography of the left coronary system demonstrated non-obstructive atherosclerosis involving the mid segment of the left anterior descending (LAD) artery and a normal circumflex (Cx) artery. The RCA originated from the mid LAD segment distal to the first septal perforator and the first diagonal branch and was free of atherosclerosis disease. A contrast-enhanced 64-slice multi-detector cardiac computed tomography showed that the LAD was severely calcified in the proximal part, and the RCA coursed anterior to the right ventricular outflow tract (RVOT) to reach the right atrioventricular groove. The patient was managed medically and became asymptomatic.

Serum Angiopoietin-Like Protein 2 Concentrations Are Independently Associated with Heart Failure.

ObjectiveAngiopoietin-like protein 2 (ANGPTL2), which is mainly expressed from adipose tissue, is demonstrated to be involved in obesity, metabolic syndrome, and atherosclerosis. Because several adipocytokines are known to be associated with heart failure (HF), here we investigated the association of ANGPTL2 and HF in Taiwanese subjects.Methods and ResultsA total of 170 symptomatic HF patients and 130 age- and sex-matched controls were enrolled from clinic. The echocardiography was analyzed in each patient, and stress myocardial perfusion study was performed for clinical suspicion of coronary artery disease. Detailed demographic information, medications, and biochemical data were recorded. Circulating adipocytokines, including tumor necrosis factor-alpha (TNF-α), adiponectin, adipocyte fatty acid-binding protein (A-FABP) and ANGPTL2, were analyzed. Compared with the control group subjects, serum ANGPTL2 concentrations were significantly higher in HF group patients. In correlation analyses, ANGPTL2 level was positively correlated to creatinine, fasting glucose, triglyceride, hsCRP, TNF-α, NT-proBNP and A-FABP levels, and negatively correlated with HDL-C and left ventricular ejection fraction. In multiple regression analysis, A-FABP, hsCRP, and HDL-C levels remained as independent predictors for ANGPTL2 level. To determine the association between serum ANGPTL2 concentrations and HF, multivariate logistic regression analyses were performed with subjects divided into tertiles by ANGPTL2 levels. For the subjects with ANGPTL2 levels in the highest tertile, their risk of HF was about 2.97 fold (95% CI = 1.24–7.08, P = 0.01) higher than those in the lowest tertile.ConclusionOur results demonstrate a higher circulating ANGPTL2 level in patients with HF, and the upregulating ANGPTL2 levels might be associated with metabolic derangements and inflammation.

50-letni mężczyzna z nawracającymi zawałami bez uniesienia odcinka ST i granicznymi zmianami w koronarografii — znaczenie diagnostyki czynnościowej

Dynamic development of invasive cardiology techniques significantly improved diagnostic and therapeutic abilities for patients with coronary artery disease. Functional assessment of coronary artery stenosis by fractional flow reserve (FFR) measurement or myocardial perfusion studies, such as single photon emission computed tomography (SPECT), allow detailed characterization of angiographically borderline atherosclerotic lesions in coronary arteries and guidance of therapeutic strategy. We present a case of a 50-year-old male hospitalized repeatedly due to non-ST segment elevation myocardial infarctions (NSTEMI). Combined functional assessment allowed correct diagnosis and optimal treatment.

Effect of CT misalignment on attenuation--corrected myocardial perfusion SPECT.

Use of CT based attenuation correction (AC) for myocardial perfusion SPECT (MPS) is growing fast due to a rapid development of hybrid SPECT/CT systems. SPECT and CT studies are performed in a sequential way extending total study acquisition and making a patient movement more likely. The present work aims at answering the question how large misalignment between SPECT and CT studies should be considered significant and how often those misregistrations are observed. A retrospective study applying AC was performed in 107 patients who had coronary angiography (CA) performed within 3 months. Patients underwent a stress/rest Tc-99m MIBI 2 day SPECT/CT myocardial perfusion study. In case of SPECT and CT misalignment CT slices were shifted manually; shifts along 3 axes were recorded and after realignment a repeat reconstruction was performed. Euclidean distance of misalignment was also calculated. Images were analyzed by two experienced nuclear medicine specialists (consensus) applying visual semiquantitative method. Perfusion of three arteries was scored using a 5 grade scale. CA results were used as a reference for MPS findings. In 47 patients (44%) CT realignment was necessary. CT was shifted mostly along x and y axes, and less often along z axis. Euclidean distance S exceeded 2 pixels in 3 stress and 2 rest studies. Only in 7 patients changes of scores assigned to coronary vessels were noted as a result of CT realignment. These changes concerned 9 vessel areas. In 7 out of 9 cases changes were noted toward a better agreement with results of CA. Only in one patient, with stress S > 3 pixels and negative result of CA, CT realignment changed vessel area score significantly, from probably abnormal to normal. Only misalignments large enough, exceeding 2–3 pixels, have negative impact on attenuation corrected images. Such misalignments are rare, in our material were observed in 3 stress and 2 rest studies (3% and 2% of all studies, respectively). Only in one patient (below 1% of all studied patients) CT misalignment caused a significant study misinterpretation. Although alignment of SPECT and CT studies should be checked in every patient, small misalignments do not affect study interpretation

Quantitative and Qualitative Evaluations of Defect Images in Different Regions of Myocardial Phantom under Implementation of Various Filters in SPECT

In myocardial perfusion single Photon Emission Computed Tomography (SPECT), images are degraded by photon attenuation, distance-dependent collimator, detector response. The filters in reconstruction process can greatly affect the quality of the SPECT images. The purpose of this study is to make quantitative and qualitative evaluation of the acquired SPECT images of similar defects which are located in the different regions of myocardial phantom under implementation of different filters. Herein, rectangular defects with the same thickness were inserted on the different regions of on the inner wall of the myocardial phantom. Myocardial perfusion study was performed with meta-stable Technetium with a dual head SPECT system. Raw data was reconstructed by filter back projection method with some filters. Then, results of implementation of various filters with different parameters on the contrast, signal to noise ratio and size of defects images in transverse, coronal and sagittal views of the phantom have been studied. The results show that contrast, signal to noise ratio and size of defects images are depending on the defect locations, type of filters and the selection of view which is examined for specified defect.