Rest Myocardial Perfusion Scintigraphy Research Articles

ECHO-MPS, a dual modality strategy of cardiac imaging to identify myocardial ischemia.

We aimed to evaluate an approach with resting echocardiography (TTE) and stress myocardial perfusion scintigraphy (MPS) compared to standard MPS in patients with stable angina and normal left ventricle (LV). We hypothesized that normal LV on TTE may allow for the elimination of rest MPS without compromising accuracy and offering an efficient diagnostic pathway with reduced radiation exposure. In a prospective, non-randomized study TTE was performed prior to MPS in patients (pts) referred for assessment of coronary artery disease (CAD). In pts with normal LV assessment was performed using the hybrid and the standard approach. TTE and MPS were interpreted by two TTE readers (ER1-2) and two MPS readers (NR1-2). ECHO-MPS was compared with standard MPS for diagnostic accuracy. 103 patients, mean age 61 ± 12 year, (63M, 40W) were recruited. Standard MPS were normal in 75 patients and abnormal in 28 patients, with the hybrid approach 79 studies were reported as normal and 24 studies as abnormal. Kappa values were 0.580, (p < 0.001) for large, 0.394, (p < 0.001) for medium, and 0.298 (p = 0.002) for small defects. With standard MPS as a reference, sensitivity for detection of perfusion defects by ECHO-MPS was 75% (95% CI 0.67-0.83) [NR2] and 78% (95% CI 0.70-0.86)[NR1]. Specificity was 95% (95% CI 0.90-0.99) [NR2] and 95% (CI 95%CI 0.90-0.99) [NR1]. ECHO-MPS protocol provides similar diagnostic accuracy as standard stress-rest MPS. In patients with normal systolic LV function in TTE, performing only stress MPS provides similar information as standard rest and stress MPS.

Myocardial Perfusion Scintigraphy in a Patient With Transposition of Great Arteries Post-Atrial Switch Surgery.

We report a case of a 33-year-old woman who underwent stress and rest myocardial perfusion scintigraphy (MPS) to exclude coronary artery disease. MPS images showed an apparent dextrocardia with a right-sided septal wall uptake. The electrocardiograph showed a right axis deviation with dominant R waves at leads aVR and V1. Upon retrieval of the patient's medical records, she had an underlying transposition of great arteries and underwent a Senning atrial switch surgery. Hence, the MPS images demonstrated a prominent right ventricular wall due to its function as the "systemic" ventricle with minimal uptake in the "pulmonary" left ventricle.

Pentoxifylline reduces inflammation and prevents myocardial perfusion derangements in experimental chronic Chagas' cardiomyopathy.

Myocardial perfusion defect (MPD) is common in chronic Chagas cardiomyopathy (CCC) and is associated with inflammation and development of left ventricular systolic dysfunction. We tested the hypothesis that pentoxifylline (PTX) could reduce inflammation and prevent the development of MPD in a model of CCC in hamsters. We investigated with echocardiogram and rest myocardial perfusion scintigraphy at baseline (6-months after T. cruzi infection/saline) and post-treatment (after additional 2-months of PTX/saline administration), female Syrian hamsters assigned to 3 groups: T. cruzi-infected animals treated with PTX (CH + PTX) or saline (CH + SLN); and uninfected control animals (CO). At the baseline, all groups showed similar left ventricular ejection fraction (LVEF) and MPD areas. At post-treatment evaluation, there was a significant increase of MPD in CH + SLN group (0.8 ± 1.6 to 9.4 ± 9.7%), but not in CH + PTX (1.9 ± 3.0% to 2.7 ± 2.7%) that exhibited MPD area similar to CO (0.0 ± 0.0% to 0.0 ± 0.0%). The LVEF decreased in both infected groups. Histological analysis showed a reduced inflammatory infiltrate in CH + PTX group (395.7 ± 88.3 cell/mm2), as compared to CH + SLN (515.1 ± 133.0 cell/mm2), but larger than CO (193.0 ± 25.7 cell/mm2). The fibrosis and TNF-α expression was higher in both infected groups. The prolonged use of PTX is associated with positive effects, including prevention of MPD development and reduction of inflammation in the chronic hamster model of CCC.

Technetium-99m labelled somatostatin analogue myocardial uptake in subacute and “old” myocardial infarction: initial experience

Background. It has been shown that prognosis following acute myocardial infarction (MI) strongly correlates with intensity of inflammatory reactions in response to myocardial injury. Thereby diagnostic methods for myocardial post-infarction inflammation (PII) monitoring are needed. Scintigraphy with somatostatin receptor targeted radiotracers has prospects for PII imaging, but its clinical value is poorly studied.Methods. Six patients with ST-segment elevation anterior myocardial infarction (STEMI) were examined by chest SPECT/СT with 99mTc-Tektrotyd and rest myocardial perfusion scintigraphy (MPS) at subacute and remote (8 th month) period of the disease. Parameters of both scintigraphic methods were estimated.Results. In subacute stage of MI myocardial perfusion defects were revealed in all 6 patients (mean SRS 11.83 ± 8.89), 99mTc-Tektrotyd uptake in myocardium was revealed in 3 of 6 patients. At remote period intense uptake of 99mTc-Tektrotyd was found only in 1 patient. This uptake was more spread and clears, comparing with accumulation in subacute stage of AMI.Conclusion. Myocardium scintigraphy with 99mTc-Tektrotyd allows identifying overexpression of somatostatin receptors in areas of recent and old myocardium infarction. In some patients the radiopharmaceutical uptake may expands to a remote period of the disease. Further larger studies and histological validation of scintigraphic results are needed.

The Utility of a Combination of 99mTc-MIBI Washout Imaging and Cardiac Magnetic Resonance Imaging in the Evaluation of Cardiomyopathy.

Background: In cardiomyopathy, 99mTc-MIBI washout can reflect mitochondrial dysfunction and late gadolinium enhancement (LGE) on cardiac magnetic imaging (MRI) is associated with tissue fibrosis. We sought to determine the relationship between 99mTc-MIBI uptake, 99mTc-MIBI washout, and LGE on MRI in patients with cardiomyopathy. Methods: Twenty-one patients underwent rest myocardial perfusion scintigraphy at 45 minutes (early) and 4 hours (delayed) after intravenous 99mTc-MIBI administration and cardiac MRI. We assessed myocardial perfusion, 99mTc-MIBI washout, and LGE. We divided the left ventricle (LV) wall into 16 segments using a polar map. Then, we classified each segment into 5 groups according to 99mTc-MIBI uptake in early-rest images and washout. Additionally, we created a contingency table based on LGE presence/absence in the groups. Results: We evaluated 336 segments in 21 patients. 99mTc-MIBI uptake was decreased in 168 segments in the early-rest 99mTc-MIBI images. 99mTc-MIBI washout was observed in 108 segments with either normal perfusion or reduced perfusion in the early-rest 99mTc-MIBI images. LGE was positive in 104 segments. A contingency table analysis with Fisher's exact test showed that LGE was observed significantly more frequently in the segments with decreased 99mTc-MIBI uptake (p<0.001). In segments without a decreased 99mTc-MIBI uptake, there was a significant correlation between increased 99mTc-MIBI washout and the presence of LGE (p=0.033). Conclusions: In cardiomyopathy, the mitochondrial dysfunction in the early stage is shown as 99mTc-MIBI washout, and fibrotic changes in the myocardium in advanced stages are shown as LGE on cardiac MRI. The severity of myocardial damage and the clinical stage of cardiomyopathy can be evaluated using multimodal imaging.

How to get the optimal defibrillation lead parameters using myocardial perfusion scintigraphy in patients with coronary artery disease.

The conventional criteria for a defibrillation lead (DL) implantation don't take into account presence of scar or deep ischemia in the myocardium. This may impair a proper functioning of the DL. We sought to optimize the DL implantation placement using rest myocardial perfusion scintigraphy (MPS), which allow detecting areas of myocardial hypoperfusion (MH). To study the influence of MH and scarring, detected by MPS, on the DL parameters in patients with coronary artery disease (CAD). 69 patients (male-65, age 64.8 ± 7.7years) with CAD and indications for ICD implantation were enrolled. Two days before ICD implantation all patients underwent MPS at rest. Then patients were divided in 2 groups. In the 1st group DL was implanted considering MPS results: to the septal position, if the most significant MH were detected in the apical segments, and to the apical position, if MH were in the septal segments. In the 2nd group DL was implanted using the conventional approach without considering MPS results. Clinical 12months follow-up was performed with ICD interrogation. Patients of both groups were comparable by clinical and scintigraphic parameters. In the same time, in the 1st group pacing threshold was lower (p < 0.0001) and ventricle signal amplitude was higher (p < 0.0001) comparing with the 2nd group at all control points. The presence of MH detected by MPS in the area of the DL placement worsens its parameters. The results of MPS in patients with CAD can be useful for optimization of DL placement.

Routine Stress-Rest Tc-99m MIBI Myocardial Perfusion Scintigraphy Underestimates Ischemia and Viability

Objective: The study included patients with known or suspected coronary artery disease. It aimed to demonstrate the incremental value of the routine nitrate augmentation in stress-rest technetium-99m methoxyisobutylisonitrile (Tc-99m MIBI) myocardial perfusion scintigraphy (MPS). Material and Methods: Standard stress and rest MPS was performed, followed by a second rest study with isosorbide dinitrate intervention within 5 days. The redistribution of Tc-99m MIBI was compared between stress and rest images, and interpretation of the study done as normal, scarred, and ischemia ± mixed lesion groups. The rest studies were compared with the rest nitrate studies. Summed rest score (SRS) and summed rest nitrate score (SRNS) were calculated. The summed difference score (SDS) of SRS and SRNS was calculated for each group. Results: A total of 50 patients were included in the study. Based on the routine MPS, patients were divided into the scar (n = 20), ischemia (n = 18), and normal (n = 12) groups. After the administration of nitrate, a significant fall in the blood pressure ( P &lt; .001) and an increase in the heart rate ( P &lt; .001) were noted. SDS was not significant in the normal MPS group (0.17 ± 0.57, P = .19). In comparison, substantial SDS was found in the ischemia ± mixed lesion (4.33 ± 3.43) and scarred (3.5 ± 3.15), respectively (both P &lt; .001). Percentage improvement in the SRS from SRNS was found less than 2% for normal MPS while 18% and 29% for scarred and mixed groups, respectively. Conclusion: Routine MPS (stress followed by rest) underestimate ischemia and viability, which can be significantly reduced by utilizing nitrate augmentation in all patients with abnormal stress MPS. This could lead to a significant change in the extent and severity of ischemia and viability.

The diagnostic efficacy and safety of stress-only supine and prone myocardial perfusion imaging with a dedicated cardiac gamma camera in patients with suspected or known coronary artery disease.

Myocardial perfusion scintigraphy remains one of the substantial noninvasive diagnostic methods in coronary artery disease. Recent technological advancement allowed to create novel semiconductor, dedicated cardiac gamma camera with better spatial resolution and higher energy resolution, resulting in the reduction of radiation burden and acquisition time. The aim of this study was to evaluate the efficacy and safety of stress-only supine and prone MPS with a cardiac gamma camera in patients with suspected or known coronary artery disease. A total number of 203 consecutive patients with suspected or known coronary artery disease, who underwent MPS were enrolled in the study. The patients without perfusion abnormalities on stress supine and prone MPS scans had no rest MPS, in the remaining patients two-day stress-rest imaging was performed. The group of 160 patients with one-year follow up was subjected to final analysis. Stress-only protocol of myocardial perfusion imaging was performed in 72 patients, 88 patients underwent two-day stress and rest myocardial perfusion scintigraphy. In 46 out of 72 stress-only group of patients, prone study did not affect further proceedings. However, in over 1/3 of cases (26/72), prone scans resulted in abstaining from rest imaging. One year follow-up revealed no sudden cardiac deaths or myocardial infarctions in both (stress-only and stress-rest) groups. Revascularization was performed most often in the double-positive group - patients with significant ischaemia on myocardial perfusion images and chest pain or electrocardiographic changes or both during the stress test. In this double-positive group, all 11 patients had coronary angiography (two of them prior to myocardial perfusion scintigraphy), nine of them had subsequent revascularization. In patients with no significant perfusion abnormalities on stress scans omitting rest study is safe with very good one-year risk prognosis of acute cardiac events and allows to limit the radiation exposure and procedure duration. Additional prone acquisitions are valuable supplements in determining the decision of safe early completion of myocardial perfusion imaging.

Nuclear Cardiology: Role in the World of Multimodality Cardiac Imaging

The concept of multimodality imaging has been developing rapidly in recent years due to the need to integrate information on anatomy (which defines coronary artery disease) with functional data (which reflects the effects of this disease on tissues) to enable the proper evaluation of patients with ischemic heart disease. From the clinical point of view, it has been well established that a complete evaluation of a coronary lesion requires not only morphological information on the location of the stenosis, but also functional information on its impact. Van Werkhoven et al have demonstrated that the combination of anatomical and functional information can improve patient risk stratification. Thus, patients with 50% coronary occlusion associated with perfusion defects experienced a higher annual event rate during follow-up (9%) than patients with no significant coronary lesions or perfusion defects (1%). While the severity of ischemia is related to the degree of stenosis, this relationship is not always linear. A number of factors apart from the degree of occlusion (assessed by coronary luminography) establish whether or not a given stenosis induces a myocardial perfusion defect. Among these factors, we stress the importance of the existence of collateral circulation and the phenomenon of arterial vasospasm, a functional mechanism that can overlap a mild fixed lesion, leading to significant occlusion. In addition, a nonsignificant arteriosclerotic plaque can become destabilized and produce serious or even total arterial occlusion. Moreover, the phenomenon of ‘‘ischemic preconditioning’’ could play a role in the discrepancy between anatomical and functional changes. Given all these circumstances, evaluation of the functional relevance of the coronary stenosis is recommended to guide revascularization strategies. If, in addition, this dual information can be obtained using noninvasive methods and can be presented jointly (by means of image fusion), the result facilitates optimal clinical decision-making, while also reducing the risk inherent in invasive diagnostic techniques. Since the 1990s, stress and rest myocardial perfusion scintigraphy has been developed as an excellent noninvasive method to obtain the functional information required for the assessment of

Stress-rest myocardial perfusion scintigraphy and adverse cardiac events in heart failure patients.

Heart failure, primarily in the elderly, is a growing epidemic in today's world. It leads to high rates of disability and mortality, as well as significant health care expenditures, making it important to assess possible predictors of adverse cardiac events. In Cuba, heart failure mortality is 19.1/100,000 population. Assess the value of stress-rest protocol gated-SPECT for identifying patients with symptomatic heart failure likely to suffer adverse cardiac events. A study was conducted of 52 patients (mean age 59 years, SD 9; 62% women) with functional capacity II/III (New York Heart Association scale) and left ventricular ejection fraction <40%. Patients were divided into two groups based on coronary heart disease diagnosis: those with coronary heart disease (41), labeled ischemic; and those without (11), labeled nonischemic. All underwent gated SPECT myocardial perfusion scintigraphy with technetium-99m-labeled methoxyisobutyl isonitrile, using a two-day stress-rest protocol, including evaluation of intraventricular synchrony by phase analysis. Patients were followed over 36 months for adverse cardiac effects. No significant differences were observed between the two groups during the stress test with regard to exercise time, metabolic equivalents or percentage of maximal heart rate during maximal stress. Summed stress, rest and difference scores, however, were significantly different between the ischemic and nonischemic groups: 16.82 (SD 6.37) vs. 7.54 (SD 5.8), p <0.001; 14.43 (SD 6.28) vs. 6.45 (SD 3.77), p = 0.001; and 2.39 (SD 4.89) vs. 1.09 (SD 3.7), p = 0.034. No differences were found in ventricular function, although stress-minus-rest left ventricular ejection fraction was slightly lower in patients with ischemic heart disease (-1.29, SD 5.8) than in patients without ischemic heart disease (1.27, SD 4.31). Dyssynchrony was greater in patients with ischemic heart disease than in those without, primarily during stress (p <0.01). The only variable that showed a possible association with the occurrence of adverse events was <5 metabolic equivalents on the stress test (p = 0.03), while resting phase SD showed only a tendency toward association (p = 0.05). Information on myocardial perfusion, functional capacity and intraventricular synchrony obtained from stress-rest gated SPECT may help identify patients with symptomatic heart failure who are likely to develop adverse cardiac events, enabling better management of higher-risk cases and improved allocation of resources.

Use of myocardial perfusion imaging and estimation of associated radiation doses in Germany from 2005 to 2012

PurposeFor several years the Working Group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine has been performing a regular survey to obtain information on technique, utilization and development of myocardial perfusion scintigraphy (MPS). Currently, data of six surveys from 2005 to 2012 are available. The aim of this paper is to deliver a general and comprehensive overview of all surveys documenting the course of patient doses over time and the development of the method.MethodsA one-page questionnaire with number of MPS patients, number of stress and rest MPS, referral structure and several technical issues was sent to all centres performing MPS in Germany and evaluated. With the data on protocol utilization, effective MPS patient doses were estimated.ResultsMPS per million population (pmp) varied between 2,380 and 2,770. In 2012, MPS pmp showed a slight increase for the first time. From 2005 to 2009 the angiography to MPS ratio increased from 3.4 to 4.4, and the revascularization to MPS ratio decreased from 0.66 to 0.53. In 2012, both indices demonstrated an opposite trend for the first time (4.1 and 0.55). A total of 108 centres participated in all surveys. They showed an increase in MPS patients of 4.0 % over the reporting period. In 2012, more than 50 % of the centres experienced no change or an increase in MPS numbers. The leading single competitor was MRI, followed by angiography and stress echocardiography. 201Tl studies have decreased since 2005 from 20 to 5 %. 99mTc MPS studies showed a mild increase in 2-day protocols. In 2012, the average effective dose per patient was estimated at 7.4 mSv. Due to the decreasing use of 201Tl, a mild decline over the observation period can be documented. Dynamic exercise stress was the most common stress test and adenosine the leading pharmacological stress agent, with a growing percentage. In 2012, the regadenoson percentage was 9 %. Gated single photon emission computed tomography (SPECT) noted an increasing acceptance with >70 % in 2012. The segmental scoring of perfusion studies had a low acceptance. Ambulatory care cardiologists represented the major referral group.ConclusionGermany has a moderate to moderate-high MPS utilization rate. Nevertheless, coronary artery disease (CAD) diagnosis and disease management are dominated by angiography. The survey data reveal a positive trend in MPS and a decrease in average patient dose reflecting good practice with guideline adherence, the implementation of technical improvements and success in training.

Myokard-Perfusions-Szintigraphie 2012 in Deutschland

SummaryAim: The working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine presents the results of the 6th survey on myocardial perfusion scintigraphy (MPS) of the reporting year 2012. Method: 278 questionnaires (177 private practices (PP), 78 hospitals (HO), 23 university hospitals (UH)) were evaluated. Results: MPS of 105,941 patients were reported. 95% [2005 = 80%] of MPS studies were conducted with 99mTc perfusion radiopharmaceuticals and only 5% with 201Tl. 79% [2009 = 76%] of the MPS were performed in PP, 15% [2009 = 17%] in HO, and 6% [2009 = 7%] in UH. Data from 108 centres which participated in all surveys from 2005 to 2012 showed an increase in MPS numbers of 4.0% (PP +6.1%, HO +18.2%, UH –18.3%). 29% of all participants (27% of PP, 31% of HO, and 26% of UH) noticed no change and 26% of all participants (28% of PP, 17% of HO and 35% of UH) an increase in their MPS requests since the 2009 query. The type of stress was pharmacological in 39% [2009 = 31%]. Of these 61% with adenosine (39% with exercise), 22% with regadenoson (51% with exercise), 14% with dipyridamole (60% with exercise), and 3% with dobutamine. Gated SPECT was performed in 73% [2009 = 56%] of all rest, in 70% [2009 = 56%] of all stress and in 67% [47%] of all stress and rest MPS. Only 36% [2009 = 33%] of the centres performed a quantification of all their studies with scores, whereas 41% [2009 = 52%] did not apply any quantification. 60% [2009 = 49%] of the MPS were requested by ambulatory care cardiologists. Conclusion: The survey on MPS in Germany reveals a good conformity of imaging procedures with the current guideline. A positive development in MPS practice and referral can be stated. However, there is still some potential of MPS processing considering the quantitative perfusion analysis.

Rest Myocardial Perfusion Scintigraphy Showing the Invasion of the Hydatid Cyst in the Myocardium

A cardiac hydatid cyst is a rare complication of the Echinococcus infection, and it is seen in just 0.5% to 2% of all cases. Because it can cause sudden death, removing the cyst is recommended. It is important to determinate the relationship between the cyst and the intra/extracardiac structures before the operation because it is of vital importance during the operation. In our case, we showed that rest myocardial perfusion scintigraphy provided an additional contribution to anatomic imaging in that it showed the invasion of the cyst in the myocardium, which was effectively directing the course of the operation.

Rapid-acquisition myocardial perfusion scintigraphy (MPS) on a novel gamma camera using multipinhole collimation and miniaturized cadmium-zinc-telluride (CZT) detectors: prognostic value and diagnostic accuracy in a 'real-world' nuclear cardiology service

To study the prognostic value of rapid-acquisition adenosine stress-rest myocardial perfusion scintigraphy (MPS) on a gamma camera using multipinhole collimation and cadmium-zinc-telluride (CZT) detectors. The secondary aim was to assess the diagnostic accuracy of the technique compared with invasive coronary angiography. Retrospective analysis of 1109 consecutive patients undergoing MPS in a routine clinical setting on a high-efficiency multipinhole gamma camera. MPS acquisition, performed with a standard injection of 550 MBq of (99m)Tc-tetrofosmin, required a mean (±SD) scanning time of 322 ± 51 s. The hard cardiac event rate at a median (inter-quartile range) follow-up of 624 (552-699) days was 0.4% (95% CI 0.1-1.1) in patients with no significant perfusion abnormality versus 6.8% (95% CI 4.3-10.7%, P < 0.001) in those with an abnormal scan. In a sub-group of 165 patients, comparison with obstructive coronary artery disease on X-ray angiography gave a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy for rapid-acquisition MPS of 84% (95% CI 74-91), 79% (95% CI 68-87), 82% (95% CI 72-89), 81% (95% CI 70-89), and 82% (95% CI 73-89), respectively. MPS performed on a CZT solid-state detector camera with multipinhole collimation is an evolutionary development that provides reliable prognostic and diagnostic information, while significantly reducing image acquisition time.

A decision support system for stress only myocardial perfusion scintigraphy may save unnecessary rest studies

Aim: It is often a practical question whether to continue with the rest study after termination of a fairly normal stress myocardial perfusion scintigraphy (MPS), in particular for physicians with limited experience. The purpose of this study was to analyze the value of using a decision support system (DSS) to guide less experienced physicians in this situation. Methods: Nine residents from eight different nuclear medicine departments interpreted 100 MPS stress studies, first without and then with access to the advice of a DSS. Each study was interpreted regarding the necessity of adding a rest study for correct interpretation of the MPS. The patients had undergone a gated stress and rest MPS, using a Tc-99m sestamibi protocol. Interpretations made by three nuclear cardiology experts, having access to all available clinical and image information, were used as the gold standard. Results: In the cases where the gold standard interpretation wanted a rest study the 9 residents asked for it in 94% and 95% before and after having access to the DSS, respectively ( p &gt;0.05). The residents did not want a rest study in 57% (without) and 69% (with the advice from the decision support system), in the patients, considered to have a normal stress study by the experts ( p &lt;0.005). The DSS significantly reduced interobserver variation among the residents. Conclusion: The present study shows that with the support of a DSS less experienced physicians get closer to the decisions of highly experienced nuclear cardiologists regarding the need of adding a rest study to a stress MPS.

Myocardial perfusion scintigraphy in Germany in 2009: utilization and state of the practice

Since 2006, the working group Cardiovascular Nuclear Medicine of the German Society of Nuclear Medicine, in cooperation with the working group Nuclear Cardiology of the German Cardiac Society, has been surveying the utilization and technical realization of myocardial perfusion scintigraphy (MPS) in Germany. This paper presents the results of the reporting year 2009. A total of 291 centres participated in the inquiry, including 179 private practices (PP), 86 hospitals (HO) and 26 university hospitals (UH). MPS of 98,103 patients were reported. The MPS numbers per million population (pmp) were estimated at 2,360; 76% of the MPS were performed in PP, 17% in HO and 7% in UH. The ratio of MPS to coronary angiography to revascularization was 0.5 to 2.3 to 1. Data from 134 centres which participated in the surveys from 2005 to 2009 showed a decrease in MPS utilization of 2.2%. Nearly half of the MPS were requested by ambulatory care cardiologists. Of all MPS studies, 89% were conducted with (99m)Tc perfusion tracers. Ergometry was the preferred stress test (69%). Adenosine was used in 16%, adenosine + exercise in 7%, dipyridamole in 3%, dipyridamole + exercise in 5% and dobutamine in <1%. Gated single proton emission computed tomography (SPECT) acquisition was performed in 56% of all rest MPS and in 56% of all stress MPS. Both rest and stress MPS were ECG gated in 41%. Only 33% of the centres always performed a quantification of the perfusion studies, whereas 51% did not apply any quantification; 4% of the MPS studies were corrected for attenuation, and 17 centres used transmission sources of 12 CT-based systems. A scan activity of 2,380 MPS pmp is in the upper third of the European range. The ratios to coronary angiography and to revascularization suggest that angiography dominates diagnosis and management of coronary artery disease (CAD). The clinical and technical realizations reveal that the predominant goals of further trainings to optimize MPS are in the field of gated SPECT and quantitative perfusion SPECT.

Stress/rest myocardial perfusion scintigraphy in patients without significant coronary artery disease

AimTo define the prognostic impact of stress myocardial perfusion scintigraphy (MPS) in patients with angiographic exclusion of significant coronary artery disease. MethodsAngiographic and MPS databases were matched to define patients without significant coronary artery disease by quantitative angiography (diameter stenosis <50%) who underwent stress MPS and coronary angiography within a time period of 3 months. A total of 118 patients were identified and followed for a mean of 6.3 ± 1.2 years for death, a composite of death, myocardial infarction, bypass surgery, or percutaneous coronary intervention [MAE]) as well as occurrence of symptoms (angina or dyspnoe class CCS II to IV). Stress and rest MPS (using 99mTc-MIBI or tetrofosmin) were analyzed by quantitative perfusion SPECT (QPS) for summed stress and rest scores (SSS/SRS). ResultsThere were 16 deaths, 29 MAE, and 76 patients with MAE or significant symptoms during follow-up. Significant differences in SSS were found between patients who died (9.5 ± 6.9 vs. 5.4 ± 5.6, P = 0.012), had MAE (8.7 ± 7.2 vs. 5.2 ± 5.0, P = 0.010), or had MAE or significant clinical symptoms (7.2 ± 7.1 vs. 4.6 ± 6.2, P = 0.042) compared to those without the respective event. Logistic regression analysis demonstrated SSS to be a predictor of death (OR = 1.074 [95% CI: 1.004-1.149], P = 0.026) and MAE (OR = 1.087 [95% CI: 1.004-1.181], P = 0.027). ConclusionsIn patients without significant angiographic coronary artery disease, the result of stress MPS is a predictor of long-term prognosis. Quantitative analysis of MPS allows definition of patients with a higher likelihood to develop clinical events or symptoms.

Can metamizol play a role in nuclear medicine practice?

I read with great interest the letter to the editor by Georgoulias et al., published in the January 2009 issue concerning the drug enhancement of myocardial tracer uptake during myocardial perfusion imaging [1]. The authors also focused on our article “Tc sestamibi myocardial perfusion scintigraphy (MPS) with the novel use of metamizol for the detection of perfusion reversibility” published in the August 2008 issue [2]. Metamizol has been in clinical use for more than three quarters of a century, and recent reports have shown that metamizol also has a relaxing activity in vascular smooth muscle as assessed in in vitro tissue bath techniques and in vivo animal models [3–8]. In our above-mentioned study [2], we aimed to investigate whether the vascular smooth muscle relaxing effect of metamizol has the potential to better define myocardial ischaemia during MPS and we found that metamizol rest MPS displayed the defect reversibility better than baseline rest MPS and that metamizol-induced myocardial sestamibi uptake was significantly higher (p<0.001) than stress/baseline rest MPS examinations. Blood pressure remained unaltered after metamizol induction. So, we concluded that metamizol increases the detection of the viable myocardium regions during MPS and helps to make a confident interpretation for defect reversibility. In their letter to the editor, Georgoulias et al. [1] summarized the use of technetium-labelled tracers (sestamibi and tetrofosmin) for the detection of viable myocardium with one or a combination of the approaches such as determining the severity of resting defects according to the percent of the peak myocardial activity, assessing the radiotracer uptake after nitroglycerin administration and assessing the regional myocardial function and thickening by performing gated SPECT. The authors also shared that they had great experience with gated SPECT on this issue and they emphasized the clinical dilemma in the differentiation of viable myocardium from scar in patients without a history of myocardial infarction who had undergone gated SPECT study. In our study [2], we postulated that since metamizol is no longer detectable in the serum soon after its oral administration, its active metabolite 4-MAA may be responsible from the enhancement of perfusion seen on MPS due to its vasorelaxing effect. 4-MAA has a longer elimination half-life (2.7 h) than nitroglycerin (a few minutes). So, Georgoulias et al. indicated that the investigation of metamizol’s influence on cardiac function would be of interest and proposed that studies are needed to increase the information regarding the use of metamizol in combination with MPS. We are of the same opinion as Georgoulias et al. on this issue. Additionally, in our opinion correlative studies comparing the effects of metamizol and nitroglycerin on the myocardial uptake of the radiopharmaceuticals might be undertaken. Metamizol might have an advantage over nitroglycerin since it causes no significant alteration in blood pressure [2], and we did not observe any complaints such as vertigo, dizziness, nausea or vomiting due to metamizol in our patients. In our above-mentioned study [2], baseline rest MPS showed an average perfusion improvement of 7.8% in the regions where stress perfusion defects were seen. On the other hand, metamizol induction displayed an average perfusion improvement of 18.2% in the same myocardial regions when compared to stress MPS. Consequently, the Eur J Nucl Med Mol Imaging (2009) 36:1191–1192 DOI 10.1007/s00259-009-1149-2

Drug enhancement of myocardial tracer uptake during myocardial perfusion imaging

Dear Sir, We read with great interest the article by Ergun et al., published in the August 2008 issue, concerning the use of metamizol during Tc-sestamibi myocardial perfusion scintigraphy (MPS), for the detection of perfusion reversibility [1]. The authors performed Tc-sestamibi MPS at stress, at rest and at rest after the oral administration of 1 g metamizol in 21 patients (14 males, 7 females; age range 46–74 years, mean age 57 years), who had partially reversible or irreversible perfusion defects on their stressrest sestamibi scintigram and no history of myocardial infarction. Metamizol-rest MPS displayed the defect reversibility better than rest MPS (defect reversibility was better delineated on metamizol-rest MPS in 33 segments, while 8 out of 14 fixed perfusion defects on stress-rest MPS were shown better on metamizol-rest MPS). Moreover, calculating sestamibi uptake ratios, metamizol-induced sestamibi uptake was significantly higher (p<0.001) than stress/baseline rest examinations. Hence, the authors concluded that “metamizol-enhanced rest MPS increases detectability of ischemic/viable myocardium during MPS” and they advocate obtaining “routine rest MPS with the induction of metamizol to increase the detection rate of the reversibility in the ischemic regions” [1]. It has been reported that technetium-labelled tracers (sestamibi, tetrofosmin) underestimate myocardial viability, mainly when blood flow is severely impaired and tracer delivery is reduced [2–4]. This observation has been supported by initial studies comparing rest-stress Tcsestamibi studies with exercise-redistribution-reinjection Tl-201 or FDG-PET imaging that have shown that Tcsestamibi underestimates viable myocardium [2–4]. However, many subsequent studies have provided convincing evidence of the potential use of Tc-sestamibi (and tetrofosmin) for viability assessment with one or a combination of these approaches: assessing the reversibility of stress-induced defects, determining the severity of resting defects (defect activity ≥60% of peak activity had high positive and negative predictive value of functional recovery after revascularization), assessing radiotracer uptake after nitroglycerin administration, and assessing regional myocardial function and thickening by performing gated-SPECT [5–7]. Nitrates (commonly 400–800 μg of sublingual nitroglycerin at least 5 min before tracer administration at rest, with the patient in the supine position to avoid symptomatic hypotension) can be administered to reduce myocardial resting hypoperfusion and to increase the correspondence of the rest imaging with myocardial viability [5–8]. This manoeuvre is indicated in patients referred for viability evaluation or with a severe defect of uptake in the stress images [8]. As nitrate administration has been used for more than 15 years to improve viability detection, a comparison of metamizol-enhanced MPS with nitrateenhanced MPS would be of significant interest. Although patients may exhibit hypotension due to nitrates, it is rarely of clinical importance when nitrates are given with the patient in the supine position [8]. Acquiring MPS data in a gated (ECG-triggered) mode and evaluating myocardial function and thickening and the related parameters (left ventricular global and regional Eur J Nucl Med Mol Imaging (2009) 36:160–161 DOI 10.1007/s00259-008-0974-z

99mTc sestamibi myocardial perfusion scintigraphy with the novel use of metamizol for the detection of perfusion reversibility

This study aims to investigate whether induction with metamizol, an analgesic-antipyretic drug having spasmolitic activity, could be used to increase the detectability of ischemic/jeopardized myocardium during MPS (myocardial perfusion scintigraphy). Metamizol-enhanced rest MPS (45 min after administration of 1 g metamizol orally, 740 MBq (99m)Tc sestamibi was injected, MPS was acquired 45 min later) was performed in 21 patients who had perfusion defects on their previous stress-rest (99m)Tc sestamibi MPS. Blood pressure was monitored at 15-min intervals. Stress, rest, metamizol-rest MPS images were interpreted on the model of 20 segments using a visual uptake score (VUS; 0 = normal, 1 = mild, 2 = moderate, 3 = significant decreases, 4 = no uptake). (99m)Tc sestamibi uptake ratios (MIBI-UR; mean counts in the region of the perfusion defect/mean counts in the region of the normal-perfused wall) were obtained on each MPS and compared with each other. Average MIBI-UR in each scintigraphic examination was calculated. MPS were compared with coronary angiography results. VUS and MIBI-UR results showed that metamizol-rest MPS displayed the defect reversibility better than rest MPS. Of the 14 segments with fixed perfusion defects on stress-rest MPS, 8 showed improvement of perfusion after metamizol induction. In 33 segments, lesion reversibility was better delineated on metamizol-rest MPS. Metamizol-induced sestamibi uptake was significantly higher (p < 0.001) than stress/baseline rest examinations as calculated by the MIBI-UR. Blood pressure remained unaltered. Coronary angiography results were in concordance with metamizol induced MPS. Metamizol-enhanced rest MPS increases detectability of ischemic/viable myocardium during MPS. Metamizol should be discontinued like nitrates before stress MPS since it may mask the visualization of ischemic perfusion defects.