Myocardial Perfusion Studies Research Articles

Prevalence and predictors of an abnormal stress myocardial perfusion study in asymptomatic patients with type 2 diabetes mellitus

The purpose of this study was to evaluate the prevalence of an abnormal stress myocardial perfusion study in a cohort of truly asymptomatic patients with type 2 diabetes mellitus using myocardial perfusion imaging by means of single photon emission computed tomography (SPECT). Secondly, we determined which clinical characteristics may predict an abnormal stress myocardial perfusion study in this population. A total of 120 asymptomatic patients (mean age 53+/-10 years) with type 2 diabetes mellitus and one or more risk factors for coronary artery disease were prospectively recruited from an outpatient diabetes clinic. All patients underwent myocardial perfusion imaging by means of adenosine (99m)Tc sestamibi SPECT. Images were evaluated for the presence of perfusion abnormalities as well as other nonperfusion abnormalities that may indicate extensive ischaemia, including left ventricular dysfunction (defined as a left ventricular ejection fraction <45%), transient ischaemic dilatation and adenosine-induced ST segment depression. Multivariable analysis was performed using a backward selection strategy to identify potential predictors for an abnormal stress myocardial perfusion study. Finally, all patients were followed up for 12 months to determine the occurrence of cardiovascular events: (1) cardiac death, (2) nonfatal myocardial infarction, (3) unstable angina requiring hospitalization, (4) revascularization, or (5) stroke. Of the 120 patients, 40 (33%) had an abnormal stress study, including myocardial perfusion abnormalities in 30 patients (25%). In 10 patients (8%), indicators of extensive (possibly balanced ischaemia) were observed in the absence of abnormal perfusion. The multivariable analysis identified current smoking, duration of diabetes and the cholesterol/high-density lipoprotein (HDL) ratio as independent predictors of an abnormal stress study. During a follow-up period of 12 months six patients (5%) had a cardiovascular event. The current study revealed a high prevalence of abnormal stress myocardial perfusion studies in patients with type 2 diabetes mellitus despite the absence of symptoms. In contrast to earlier studies, current smoking, duration of diabetes and the cholesterol/HDL ratio were identified as independent predictors of an abnormal study.

Role of Real Time Three‐Dimensional Echocardiography in Heart Failure

The incidence and prevalence of heart failure (HF) are increasing with high morbidity and mortality rates. Echocardiography is a very useful diagnostic tool for the evaluation of HF patients. Real time three-dimensional echocardiography (RT3DE) was introduced in the last decade and has proved to provide an accurate assessment of ventricular volume, mass, and function. In addition, it provides a comprehensive evaluation of the valves. However, its application remained limited to research work in selected cases because of a suboptimal image quality. The recent advances in the transducer and computer software technology enhanced the use of RT3DE in clinical practice. The application of RT3DE adds much information that helps in the assessment of HF patients. RT3DE became the standard in the assessment of left ventricular (LV) volumes, function, and mass. RT3DE is a promising tool for testing LV dyssynchrony due to its accuracy and reproducibility comparable to magnetic resonance imaging. The application of RT3DE for stress and myocardial perfusion studies is encouraging due to its short image acquisition time, but still requires wide-scale studies. Through cropping of the RT3DE full-volume, the direct visualization of the heart valves (especially mitral valve) in a surgical view could be easily obtained. In the near future, one would expect RT3DE to become an integral part of the assessment of HF patients.

Utilidad de los valores de función ventricular obtenidos mediante gated-SPECT post-estrés en población diabética con sospecha clínica de cardiopatía isquémica

ObjectiveTo assess the clinical usefulness of left ventricular function values obtained using post-stress myocardial perfusion gated-SPECT in diabetic patients with suspected ischaemic heart disease (IHD). Materials and methodsSixty-one patients with diabetes mellitus (DM), with clinical suspicion of IHD and no previous history of heart disease were studied. Ergometric or pharmacological post-stress myocardial perfusion gated-SPECT was performed on all patients. The relationship between the ejection fraction values and ventricular volumes, and the perfusion study results, final diagnosis, severity of the perfusion defects and the clinical evolution was studied. The mean follow-up time was 14 months. ResultsAll the ventricular function values independently showed significant differences between the groups with a normal and pathological perfusion study, and between groups with a final diagnosis of IHD and non-IHD. After multivariate logistic regression, the end-diastolic volume (EDV) was the only value which showed a statistical association with the pathological perfusion study, its severity and the final diagnosis of IHD. No statistical association was observed between the ventricular function values and the occurrence of cardiac events. ConclusionsAll the ventricular function values obtained by gated-SPECT added diagnostic information to the post-stress myocardial perfusion study in the diabetic population with suspected IHD; however, only EDV showed a statistical association with the pathological perfusion study, severity of defects and the final diagnosis of IHD.

Usefulness of ventricular function values obtained using post-stress gated-SPECT in a diabetic population with clinical suspicion of ischaemic heart disease

Objective To assess the clinical usefulness of left ventricular function values obtained using post-stress myocardial perfusion gated-SPECT in diabetic patients with suspected ischaemic heart disease (IHD). Materials and methods Sixty-one patients with diabetes mellitus (DM), with clinical suspicion of IHD and no previous history of heart disease were studied. Ergometric or pharmacological post-stress myocardial perfusion gated-SPECT was performed on all patients. The relationship between the ejection fraction values and ventricular volumes, and the perfusion study results, final diagnosis, severity of the perfusion defects and the clinical evolution was studied. The mean followup time was 14 months. Results All the ventricular function values independently showed significant differences between the groups with a normal and pathological perfusion study, and between groups with a final diagnosis of IHD and non-IHD. After multivariate logistic regression, the end-diastolic volume (EDV) was the only value which showed a statistical association with the pathological perfusion study, its severity and the final diagnosis of IHD. No statistical association was observed between the ventricular function values and the occurrence of cardiac events. Conclusions All the ventricular function values obtained by gated-SPECT added diagnostic information to the post-stress myocardial perfusion study in the diabetic population with suspected IHD; however, only EDV showed a statistical association with the pathological perfusion study, severity of defects and the final diagnosis of IHD.

Single injection, double acquisition: a double-edged sword?

In the clinical arena detection of myocardial viability is currently based on the use of nuclear techniques, which show preserved tracer uptake and metabolism in viable myocardium [1, 2]. Assessment of myocardial viability and ischemia continues to be an issue in patients with coronary artery disease and left ventricular dysfunction, in particular in patients following a myocardial infarction [3]. Nuclear imaging has long played an important role in this field. Especially PET imaging using 18F-fluorodeoxyglucose (FDG-PET) has been regarded as the metabolic gold standard of tissue viability, which has been supported by a wide clinical experience [4]. Viability assessment using SPECT techniques has gained more wide-spread clinical acceptance than PET, because it is more widely available at lower cost [5]. Moreover, technical advances in SPECT technology such as gated SPECT imaging further improve the diagnostic accuracy of the test [6–9]. During the past decade progress in the field of myocardial perfusion imaging has resulted in a myriad of choices for perfusion imaging protocols, including choices in types of stressor, imaging modality, perfusion tracer, method of analysis, and a wide range of choices of imaging protocols [10–12]. More recently, the peculiar contribution of gated SPECT in the assessment of myocardial ischemia and viability has been demonstrated, with the potential to evaluate in a single myocardial perfusion study the presence of preserved tracer uptake and the amount of contractile reserve through the acquisition of gated SPECT during inotropic stimulation with dobutamine [13–16]. In 1999, Everaert et al. did already study changes in global and regional left ventricular function in response to dobutamine infusion assessed in 10 healthy volunteers using sequential gated SPECT myocardial perfusion acquisitions [13]. The authors concluded that changes in wall thickness induced by infusion of low-dose dobutamine can be assessed by sequential gated SPECT myocardial perfusion studies. Based on this study it was suggested that the stress gated SPECT protocol proposed in their study might be helpful to distinguish viable from scar tissue in patients with coronary artery disease by demonstrating a preserved inotropic response in hypoperfused myocardium. In 2000, Narula et al. evaluated dual-isotope, gated SPECT imaging combined with low and high dose dobutamine as a single test for the characterization of various types of altered myocardial dysfunction [14]. They studied 54 patients with ischemic cardiomyopathy using rest and 4 h-redistribution thallium-201 imaging and dobutamine technetium-99m sestamibi SPECT and showed that this new imaging technique allowed the characterization of dysfunctional myocardium as stunned, hibernating, remodeled and E. E. van der Wall (&) Y. G. America A. J. Scholte J. J. Bax Department of Cardiology, Leiden University Medical Center, P.O. Box 9600, Leiden, The Netherlands e-mail: e.e.van_der_wall@lumc.nl

Myocardial perfusion study in patients who do not reach submaximal frequency on ergometry

He aim of the study was to evaluate the sensitivity and specificity of TI-201 myocardial perfusion SPECT for the diagnosis of ischaemic cardiopathy in a group of patients with chronotropic insufficiency. Materials and methods The examinations of 750 patients who had attended for the diagnosis of ischaemic cardiopathy during 2005-2006 were selected. 28% (n = 209) did not reach submaximal heart rate. Data on the diagnosis was collected in 112 by telephone interview. Ergometry and SPECT were carried out following the usual techniques. Results Patients who reached submaximal frequency and patients with chronotropic insufficiency did not show differences in age and exercise time. The proportion of patients on betablocker treatment, with clinically positive ergometries and pathological SPECT was higher in the patient group which had not reached 85% of their maximum heart rate. The data obtained in the patient group which did not reach submaximal heart rate and followed-up by telephone interview showed a SPECT sensitivity of 84% and specificity of 96%. The sensitivity of the ergometry was 25% and its specificity was 96%. Conclusions Ergometry with myocardial perfusion SPECT has adequate sensitivity and specificity for the diagnosis of ischaemic cardiopathy, even in patients with chronotropic incompetence. The proportion of pathological examinations is higher in those patients in whom tachycardia could not be sufficiently induced, which seems to indicate that the inability to reach submaximal heart rate is related with a higher probability of having ischaemic cardiopathy.

Acceleration of Monte Carlo-based scatter compensation for cardiac SPECT

Single proton emission computed tomography (SPECT) images are degraded by photon scatter making scatter compensation essential for accurate reconstruction. Reconstruction-based scatter compensation with Monte Carlo (MC) modelling of scatter shows promise for accurate scatter correction, but it is normally hampered by long computation times. The aim of this work was to accelerate the MC-based scatter compensation using coarse grid and intermittent scatter modelling. The acceleration methods were compared to un-accelerated implementation using MC-simulated projection data of the mathematical cardiac torso (MCAT) phantom modelling 99mTc uptake and clinical myocardial perfusion studies. The results showed that when combined the acceleration methods reduced the reconstruction time for 10 ordered subset expectation maximization (OS-EM) iterations from 56 to 11 min without a significant reduction in image quality indicating that the coarse grid and intermittent scatter modelling are suitable for MC-based scatter compensation in cardiac SPECT.

Assessing the effect of increasing injection activity for myocardial perfusion imaging in overweight patients

In our previous publication, we proposed to increase the injection activity for overweight patients. We have now implemented this for our patients, i.e. increasing the activity for patients above 99 kg. In the present study, we audited whether this increased activity for overweight patients improved the myocardial counts effectively and also whether it improved the image quality for these patients. 125 consecutive normal myocardial perfusion studies were included into the study. The total left ventricular myocardial count was calculated, as was the total left ventricular myocardial volume using the Cedar Sinai QPS program. The myocardial count per millilitre of the myocardium (c ml(-1)) was correlated with patient weight using regression analysis. There was no significant difference (p = 0.120) among the mean myocardial counts for patients over 99 kg (n = 40, 1548 c ml(-1)) compared with patients in the 70-79 kg range (n = 26, 1746 c ml(-1)). This indicates that the previously proposed algorithm for adjusting injection activity maintains the count density in the myocardium and should be used for all patients over 99 kg. There was, however, a significant steady decrease with increased weight in the myocardial counts for patients under 100 kg (p<0.001), a range in which injection activity was not adjusted for weight. To correct for this, we now propose that the injection activity should be adjusted for all patients over 80 kg, using the previously proposed algorithm.

SU‐GG‐I‐20: Dynamic Volume CT: Technical Aspects and Image Quality of the Aquilion ONE

Purpose: In order to cover entire organs, multislice CT requires helical acquisition. This need for table motion in multislice CT causes image volumes acquired for whole organ motion and perfusion studies to lack temporal uniformity. Dynamic volume CT mitigates this limitation by providing the ability to acquire an entire organ with isotropic resolution in a single gantry rotation with no table movement. The purpose of this study is to examine the technical aspects of the Aquilion ONE, the first dynamic volume CT scanner, and the effect on image quality versus a standard 64‐slice system. Method and Materials: An Aquilion ONE with a detector configuration of 320× 0.5mm channels is examined and compared to an Aquilion 64 with a 64×0.5mm detector configuration. Studies performed include low contrast resolution, high contrast resolution, uniformity, slice sensitivity profile, and CT number accuracy. These studies were performed using a CATPHAN 500. Results: The technical challenges associated with dynamic volume, such as cone beam reconstruction, and their physics implications, such as image clipping, will be presented. It will be shown that low contrast, high contrast, slice sensitivity profile, and CT number accuracy are equivalent to a standard 64‐slice system. Some differences in uniformity were found and will be discussed. Conclusion: Dynamic volume CT allows clinicians to visualize contrast flow, motion dynamics, and entire volumes at a single instant in time while maintaining the image quality found on current systems. Dynamic volume CT promises to transform the way medicine approaches stroke patients, myocardial perfusion studies, and imaging of other moving body parts such as the lung and joints.

Effectiveness of Anemia and Chronic Kidney Disease as Predictors for Presence and Severity of Coronary Artery Disease in Patients Undergoing Stress Myocardial Perfusion Study

Chronic kidney disease (CKD) and anemia portend a higher risk of cardiac events and mortality. We sought to ascertain whether coronary artery disease (CAD) by myocardial perfusion single-photon emission computed tomography is more common in patients with CKD (glomerular filtration rate < or =60 ml/min/1.73 kg/m(2)) and/or anemia (hemoglobin level < or =13 g/L) and the impact of different degrees of CKD. One thousand five hundred eighty patients (mean age 65 +/- 10 years) underwent gated myocardial perfusion single-photon emission computed tomography and clinical evaluation. Patients were divided into 4 groups (group 1, no anemia/no CKD, n = 800; group 2, anemia/no CKD, n = 195; group 3, CKD/no anemia, n = 332; group 4, anemia/CKD, n = 253). Multivariate logistic regression analysis was undertaken to examine the association of these diagnoses with abnormal myocardial perfusion single-photon emission computed tomogram. Compared with patients with neither diagnosis, an abnormal scan was more common in those with anemia or CKD. Patients with anemia and CKD exhibited more severe CAD (mean summed stress score 6.8 vs 4.7, p <0.01). Established high-risk findings were more prevalent in patients with anemia and/or CKD, including a summed stress score > or =8, transient ischemic dilation, or a left ventricular ejection fraction < or =40% (group 1 28%, group 2 38%, group 3 38%, group 4 48%, all p values <0.01). Patients with moderate CKD demonstrated an increased risk of an abnormal scan (odds ratio 2.66, p <0.0001). After adjustment in multivariate analysis, anemia and CKD each remained predictors for an abnormal scan. The association was stronger in those with the 2 conditions (odds ratio for high-risk scan 1.89, p = 0.0002). In conclusion, in patients with suspected CAD, anemia and CKD are predictors of myocardial perfusion single-photon emission computed tomographic markers for worsened outcomes. The relation was independent of other risk factors, supporting the inclusion of anemia and CKD in global risk assessment for patients with suspected CAD.

Investigation of Emission–Transmission Misalignment Artifacts on Rubidium-82 Cardiac PET with Adenosine Pharmacologic Stress

This study was undertaken to determine if artifacts from misalignment of cardiac emission to transmission data is present in adenosine stress studies and if the artifact could be reproduced by intentional misalignment in normal exams. Seventy consecutive 82Rb myocardial perfusion studies were reviewed. Utilizing a quality control program, misalignment was assessed. The study was reprocessed after manual realignment to determine if the defect extent changed. Emission and transmission acquisitions in six normal studies also were intentionally misaligned. Twenty of 69 rest studies (29.0%) and 17 of 69 (24.6%) stress studies demonstrated misalignment. In four patients with stress misalignment, there was a significant change in clinical interpretation. Upon intentionally misaligning six normal studies, a lateral wall defect was reproduced. Emission-transmission misalignment occurs in 29.0% and 24.6% of 82Rb rest and adenosine stress studies, respectively. While there is a positive correlation of artifactual defects with misalignment, the presence and size of artifacts is variable and unpredictable at seemingly lesser degrees of misalignment.

Regadenoson in the detection of coronary artery disease

Myocardial perfusion studies use either physical exercise or pharmacologic vasodilator stress to induce maximum myocardial hyperemia. Adenosine and dipyridamole are the most commonly used agents to induce coronary arterial vasodilation for myocardial perfusion imaging. Both cause frequent undesirable side-effects. Because of its ultrashort half-life, adenosine must be administered by constant intravenous infusion during the examination. A key feature of an ideal A2A agonist for myocardial perfusion imaging studies would be an optimal level and duration of hyperemic response. Drugs with a longer half-time and more selective A2A adenosine receptor agonism, such as regadenoson, should theoretically result in a similar degree of coronary vasodilation with fewer or less severe side-effects than non-selective, ultrashort-lasting adenosine receptor stimulation. The available preclinical and clinical data suggest that regadenoson is a highly subtype-selective, potent, low-affinity A2A adenosine receptor agonist that holds promise for future use as a coronary vasodilator in myocardial perfusion imaging studies. Infusion of regadenoson achieves maximum coronary hyperemia that is equivalent to adenosine. After a single bolus infusion over 10 s, hyperemia is maintained significantly longer (approximately 2-5 min) than with adenosine, which should facilitate radionuclide distribution for myocardial perfusion imaging studies. In comparison with the clinically competitive A2A adenosine receptor agonist binodenoson, regadenoson has a several-fold shorter duration of action, although the magnitude of hyperemic response is comparable between the two. The more rapid termination of action of regadenoson points to an advantage of enhanced control for the clinical application. Regadenoson selectively causes vasodilation of the coronary circulation, whereas effects on systemic blood pressure are only mild. The clinical adverse effect profile of regadenoson appears to be favorable, particularly with respect to dreaded atrioventricular conduction disturbances and bronchospasm.

Contrast echocardiography--limits and possibilities in cardiologic diagnosis

After injection of biocompatible fluids, contrast echocardiograms are obtained by ultrasound reflection from microbubbles in the streaming blood, which is thus opacified analogous to angiocardiography. As the microbubbles cannot pass the pulmonary capillaries, left heart contrasts are usually not seen after peripheral venous injection. Especially intracardiac shunts and valvular deficiencies may be recognized by this technique, which became an important diagnostic tool in the diagnosis of congenital heart disease and in critically ill patients. The blurred border between the opacified cavity and the myocardium may be abolished by digital image enhancement techniques, applied to contrast echocardiograms, thus making these pictures more suitable for volume determination and ventricular function analysis than non-contrast echocardiograms. Newer contrast agents such as mini-microbubbles are able to pass the pulmonary vascular bed after venous injection. Furthermore, myocardial perfusion studies are being conducted in animals by opacification of the myocardium with echo contrast agents in order to detect ischaemic areas.

Myocardial Ischemia Diagnosed by Dual-Energy Computed Tomography

For decades, dual-energy imaging has been used for tissue differentiation with several x-ray–based imaging modalities, exploiting the fact that the tissues in the human body show different absorption characteristics when penetrated with different x-ray spectra, spectra that are typically generated by different kV settings of the x-ray tube. Recently, dual-source computed tomography (CT) with 2 x-ray tubes and 2 detector arrays mounted in the same gantry has become available.1 After experience with earlier experimental prototypes, this dual-source CT for the first time enables the clinical acquisition of dual-energy CT studies simultaneously with a single scan. We used a dual-source CT scanner (Definition, Siemens, Forchheim, Germany) in dual-energy mode for performing coronary CT angiography in a 74-year–old woman with suspected coronary artery disease and prior abnormal nuclear rest/stress single-photon emission CT (SPECT). The CT scan was acquired with retrospective ECG-gating and the following scan parameters: 330-ms gantry rotation, pitch 0.2, and 32×2×0.6-mm …

Invasive Versus Noninvasive Evaluation of Coronary Artery Disease

We sought to compare the diagnostic information obtained from noninvasive characterization of coronary artery disease by using multidetector computed tomography (MDCT) and myocardial perfusion imaging (MPI) and to compare findings with the use of invasive coronary angiography and intravascular ultrasound (IVUS). Preliminary comparisons have suggested that abnormal myocardial perfusion studies correlate well with significant luminal stenosis on MDCT coronary angiography. However, atherosclerotic coronary lesions may be detectable with the use of MDCT even in the presence of normal myocardial perfusion We performed MDCT, MPI, and conventional coronary angiography in 70 patients. In addition, IVUS was performed in 53 patients. Quantitative information was obtained from quantitative coronary angiography (QCA) and IVUS assessment of plaque burden and minimal luminal area. Of 26 patients with an abnormal MPI study, 23 (88%) showed significant stenosis on MDCT. As compared with QCA, MDCT showed a sensitivity of 96% and specificity of 67% for the detection of stenoses > or =50% diameter narrowing in these patients. Mean diameter stenosis on QCA was 76% and mean minimal lumen area in IVUS was 3.3 mm(2). On the other hand, 27 (84%) of 44 patients with normal MPI had evidence of coronary atherosclerosis on MDCT (luminal stenosis > or =50%: n = 15, luminal stenosis <50%: n = 12, sensitivity of 100% and specificity of 83% as compared with QCA). Using IVUS, we found substantial plaque burden (mean 58.9 +/- 18.1% of cross-sectional area), but presence of a stenosis (minimal lumen area <4.0 mm(2)) in only 14 patients (mean minimal lumen area, 5.8 +/- 3.3 mm(2)). Only 7 patients with normal myocardial perfusion scans demonstrated absence of coronary atherosclerosis by MDCT. Considerable plaque burden can be observed with MDCT even in the absence of myocardial perfusion abnormalities. This finding does not constitute a false-positive MDCT result, but rather reflects the fact that MDCT can detect atherosclerotic lesions that are not flow-limiting.

Comparison between 180° and 360° acquisition arcs with and without correction by CT-based attenuation maps in normal hearts at rest

To investigate the effect of acquisition arc (180 degrees or 360 degrees ) and attenuation correction (AC), in artifact occurrence and image uniformity of myocardial perfusion SPECT studies in normal hearts. Twenty male and 44 female patients with primary hyperparathyroidism and low probability of resting perfusion abnormalities were analysed. Tc-sestamibi myocardial perfusion studies were performed at rest with a hybrid SPECT/CT system. An anthropomorphic phantom was also imaged. Without AC, a 360 degrees orbit resulted in significantly lower artifact rates compared to the standard 180 degrees in both gender groups. Differences persisted (P<0.001) even after adjusting reconstruction filter settings to compensate for disproportionate count statistics between the two arcs. However, gender-related variation was not considerably decreased and sub-diaphragmatic activity was augmented with a 360 degrees arc. After AC with either arc, substantially lower defect scores and minimal gender-related differences were obtained compared to the standard technique. A 360 degrees arc yielded lower defect rates and count variability than did the 180 degrees arc (P<0.05). These differences were small and were eliminated after weighting for dissimilar count statistics. Sub-diaphragmatic signal was amplified, particularly with 360 degrees ; severe bowel-myocardial activity overlap complicated image interpretation in 14% of cases with 360 degrees versus 8% with 180 degrees . In certain aspects, phantom imaging findings diverged from patient studies. Without AC there is significant disparity between 180 degrees and 360 degrees concerning artifact occurrence. After CT-based AC differences between arcs in defect rate and image uniformity seem less critical. However, 180 degrees is favoured by less intensification of intestinal activity.

EANM/ESC guidelines for radionuclide imaging of cardiac function

Radionuclide imaging of cardiac function represents a number of well-validated techniques for accurate determination of right (RV) and left ventricular (LV) ejection fraction (EF) and LV volumes. These first European guidelines give recommendations for how and when to use first-pass and equilibrium radionuclide ventriculography, gated myocardial perfusion scintigraphy, gated PET, and studies with non-imaging devices for the evaluation of cardiac function. The items covered are presented in 11 sections: clinical indications, radiopharmaceuticals and dosimetry, study acquisition, RV EF, LV EF, LV volumes, LV regional function, LV diastolic function, reports and image display and reference values from the literature of RVEF, LVEF and LV volumes. If specific recommendations given cannot be based on evidence from original, scientific studies, referral is given to "prevailing or general consensus". The guidelines are designed to assist in the practice of referral to, performance, interpretation and reporting of nuclear cardiology studies for the evaluation of cardiac performance.

Sodium sulfate as an eluant for concentrated solution of pertechnetate

Fission molybdenum-99 based technetium-99m chromatography generators are the most widely employed generator systems in the field of diagnostic nuclear medicine. In the first week these generators provide high specific volume activity Na 99mTcO 4, but in the second week the radioactive concentration of the eluate ( 99mTc) becomes ⩽17% of that at the beginning of the first week. Low specific volume activity limits the clinical procedures (e.g. 99mTc-DTPA for lung ventilation scanning, 99mTc-sestamibi for myocardial perfusion studies, 99mTc-ECD for brain imaging and 99mTc-red cells for testicles) that can be performed at the beginning of the second week. To overcome such limitations sodium sulfate was used as an eluant, which provides >80% of 99mTc radioactivity in 2 ml solution, while 0.9% NaCl provides only 40–45% 99mTc in first 2 ml solution.

Relation Between Stress-Induced Myocardial Perfusion Defects on Cardiovascular Magnetic Resonance and Coronary Microvascular Dysfunction in Patients With Cardiac Syndrome X

The purpose of this study was to investigate whether a direct relation can be demonstrated between myocardial perfusion defects detected during dobutamine stress test (DST) by cardiovascular magnetic resonance (CMR) and impairment of coronary microvascular dilatory function in patients with cardiac syndrome X (CSX). Despite the fact that coronary microvascular dysfunction has been shown in most patients with CSX, the ischemic origin of CSX remains debated. No previous study assessed whether a strict relation exists between abnormalities in myocardial perfusion and coronary microvascular dysfunction in CSX patients. Eighteen CSX patients (mean age 58 +/- 7 years, 7 men) and 10 healthy control subjects (mean age 54 +/- 8 years, 4 men) underwent myocardial perfusion study by gadolinium-enhanced CMR at rest and at peak DST (maximal dose 40 microg/kg/min). Coronary flow response (CFR) to adenosine (140 microg/kg/min in 90 s) in the left anterior descending (LAD) coronary artery was assessed by high-resolution transthoracic echo-Doppler and expressed as the ratio between coronary flow velocity at peak adenosine and at rest. At peak DST, reversible perfusion defects on CMR were found in 10 CSX patients (56%) but in none of the control subjects (p = 0.004). The CFR to adenosine in the LAD coronary artery was lower in CSX patients than in control subjects (2.03 +/- 0.63 vs. 3.29 +/- 1.0, p = 0.0004). The CSX patients with DST-induced myocardial perfusion defects in the LAD territory on CMR had a lower CFR to adenosine compared with those without perfusion defects in the LAD territory (1.69 +/- 0.5 vs. 2.31 +/- 0.6, p = 0.01). A significant correlation was found in CSX patients between CFR to adenosine and a DST perfusion defect score on CMR in the LAD territory (r = -0.45, p = 0.019). Our data concurrently show DST-induced myocardial perfusion defects on CMR and reduced CFR in the LAD coronary artery territory in CSX patients, thus giving strong evidence that a dysfunction of coronary microcirculation resulting in myocardial perfusion abnormalities is present in these patients.

Can Coronary Calcification Define the Warranty Period of a Normal Myocardial Perfusion Study?

Can Coronary Calcification Define the Warranty Period of a Normal Myocardial Perfusion Study?