Although diagnostic algorithms for the evaluation of patients with suspected coronary artery disease (CAD) are well defined [ 1 Fox K. Garcia M.A.A. Ardissino D. et al. Guidelines on the management of stable angina pectoris: executive summary: the Task Force on the Management of Stable Angina Pectoris of the European Society of Cardiology. Eur Heart J. 2006; 27: 1341-1381 Crossref PubMed Scopus (1204) Google Scholar , 2 Kolh P. Wijns W. Danchin N. et al. Guidelines on myocardial revascularization. Eur J Cardiothorac Surg. 2010; 38: S1-S52 Crossref PubMed Scopus (309) Google Scholar , 3 Smeeth L. Skinner J.S. Ashcroft J. Hemingway H. Timmis A. NICE clinical guideline: chest pain of recent onset. Br J Gen Pract. 2010; 60: 607-610 Crossref PubMed Scopus (32) Google Scholar ], the gap between guidelines and daily routine is well known, resulting in considerable variations in the utilization of technologies [ 4 Cook S. Walker A. Hügli O. Togni M. Meier B. Percutaneous coronary interventions in Europe: prevalence, numerical estimates, and projections based on data up to 2004. Clin Res Cardiol. 2007; 96: 375-382 Crossref PubMed Scopus (62) Google Scholar , 5 Maier W. Abay M. Cook S. et al. The 2002 European registry of cardiac catheter interventions. Int J Cardiol. 2006; 113: 299-304 Abstract Full Text Full Text PDF PubMed Scopus (21) Google Scholar ]. However, our knowledge is limited regarding the consequences of this heterogeneity. In the current work we depict a characteristic bias in patient selection in relation to changing diagnostic utilisation.

OBJECTIVES The aim of this study was to quantitatively evaluate myocardial flow reserve in patients early after coronary stent implantation using positron emission tomography.BACKGROUND Delayed restoration of coronary flow reserve after percutaneous transluminal corollary angioplasty (PTCA) has been observed using a variety of techniques. Altered distal vasoregulation as well as residual stenosis have been considered possible explanations for this phenomenon. Although the implantation of stents may influence some of these mechanisms, little data are available characterizing coronary flow reserve early after stent placement.METHODS In 14 patients 1.6 +/- 0.6 days after stenting, N-13-ammonia positron emission tomographic studies were performed at rest and during adenosine-induced vasodilation. Myocardial blood flow was quantified using a three-compartment model. Rest and stress flow data, as well as coronary flow reserve of stented vascular territories, were compared with that of remote areas.RESULTS The stenosis decreased from 72.1 +/- 7.3% to 3.7 +/- 6.7% after stent implantation. Coronary flow in the stented areas did not differ significantly from that in remote areas either at rest (76.1 +/- 18.5 and 75.7 +/- 17.7 ml/min/100 g, respectively), or during maximal vasodilation (205.5 +/- 59.9 and 179.4 +/- 47.4 ml/min/100 g, respectively). In addition, there was no significant difference in the calculated values of coronary reserve of these two regions (2.74 +/- 0.64 and 2.43 +/- 0.55, respectively).CONCLUSIONS The mechanical support of dilated arteries by a stent not only restores the macroscopic integrity of epicardial arteries, but also results, in contrast to conventional PTCA procedures, in early recovery of flow reserve. (J Am Cell Cardiol 1999;34:1036-41) (C) 1999 by the American College of Cardiology.

Objectives. The purpose of this study was to assess the efficacy of attenuation-corrected (AC) technetium-99m (Tc-99m)-tetrofosmin single-photon emission computed tomography (SPECT) in detecting viable myocardium compared to F-18-fluorodeoxyglucose (FDG) positron emission tomography (PET).Background. The role of Tc-99m-labeled perfusion tracers in the assessment of myocardial viability remains controversial. Attenuation artifacts affect the diagnostic accuracy of SPECT images.Methods. Twenty four patients with coronary artery disease (mean left ventricular ejection fraction 30%) underwent resting Tc-99m-tetrofosmin SPECT and FDG PET imaging, Both AC and non-attenuation-corrected (NC) SPECT images were generated,Results. Using a 50% threshold for viability by FDG PET, the percentage of concordant segments of viability between Tc-99m-tetrofosmin and FDG on the patient basis increased from 79.8% +/- 14.0% (mean +/- SD) on the NC images to 90.8% +/- 10.6% on the AC images (p = 0.002). The percentage of Tc-99m-tetrofosmin defect segments within PET-viable segments, an estimate for the degree of underestimation of viability, decreased from 19.8% +/- 15.2% on the NC images to 9.7% +/- 12.6% on the AC images (p = 0.01), Similar results were obtained when a 60% threshold was used to define viability by FDG PET. When the anterior-lateral and inferior septal regions were separately analyzed, the effect of attenuation correction was significant only in the inferior-septal region.Conclusions. The results indicate that AC Tc-99m-tetrofosmin SPECT improves the detection of viable myocardium mainly by decreasing the underestimation of viability particularly in the inferior septal region, although some underestimation/overestimation of viability may still occur even with attenuation correction. (C) 1998 by the American College of Cardiology.

Radiofrequency catheter ablation (RFCA) is an effective treatment for the interruption of accessory bypass tracts in WPW syndrome or the modification of the AV-nodal conduction system in patients with AV-nodal tachycardias. However RFCA may also damage cardiac innervation. The purpose of this pilot study was to assess possible changes in sympathetic innervation after RFCA as evaluated by the cathecholamine analog carbon-11-hydoxyephedrine (HED) positron emission tomography (PET) which allows the visualisation of sympathetic nerve terminals. We investigated nine patients with supraventricular tachycardias before and two to six weeks after RFCA. Myocardial perfusion was depicted by n-13-ammonia-PET. In addition to visual analysis, HED retention was quantified in the myocardial quadrant distal to the location of intervention; these results were compared with values in remote areas. Before RFCA, myocardial perfusion showed homogenous distribution in 8 of 9 patients. One patient showed a perfusion defect in the posterior wall. HED retention matched perfusion distribution in all patients. After RFCA there was no significant change observed either in ammonia or in HED distribution. Quantitative HED retention data showed no significant change before versus after RFCA. Thus, HED-PET does not demonstrate any abnormalities of tracer uptake indicating integrity of sympathetic nerve terminals after radiofrequency ablation therapy.

Common primers which amplify the 3' terminal genomic RNAs of Allium carlaviruses were designed based on the nucleotide sequence of shallot latent virus (SLV), garlic latent virus (GLV) and garlic common latent virus (GCLV). A total of fifteen cDNAs encoding the coat protein (CP) of the carlaviruses, including the biologically identified isolates SLV, GLV and GCLV as well as viruses from infected Allium plants cultivated in different parts of the world, were amplified by RT-PCR with the common primers. The cDNAs were then cloned and sequenced. The predicted viral CP amino acid sequence as well as the nucleotide sequence revealed that SLV and GLV, previously considered as separate viruses on the basis of their biological and physical properties, belong to the same species of the genus Carlavirus. Both viruses are clearly differentiated from GCLV. In addition, every SLV and GLV isolate from the Allium plants in Taiwan showed characteristic and common variations in their CP sequences, suggesting the possible presence of geographical variants. However, no apparent sequence variations of SLV and GLV related to their host plant species, including A. sativum, A. wakegi, A. chinense, A. fistulosum, A. cepa and A. ampeloprasum, were observed. These findings suggested that the sequence variations observed in the respective virus isolates do not correlate with the specificity of their infectivities for Allium species.

UNLABELLEDCoronary stent implantation is an increasingly accepted revascularization method. The 20%-30% restenosis rate during the first 6 mo requires a close follow-up of the patients. Since there is very little data available defining the role of perfusion scintigraphy in the management of this population, the aim of this study was to assess the diagnostic performance of stress myocardial perfusion imaging for detecting restenosis in patients after coronary stent implantation.METHODSIn 82 patients, 93 rest or stress SPECT studies were performed using 201Tl and 99mTc-hexakis-2-methoxyisobutyl isonitrile to evaluate 99 vascular territories with implanted coronary stents. The average interval between the stent implantation and the scintigraphic study was 210.5 +/- 129.6 days. The scintiscans were visually evaluated. A stress-induced perfusion defect with reversibility at rest was used as the criterion for stent restenosis.RESULTSCoronary angiography revealed a stenosis of > 50% diameter in the region of the stent in 19 arteries, while in 80 arteries there was no evidence of restenosis angiographically. With perfusion scintigraphy, 15/19 vascular territories with restenosed stents showed stress-induced perfusion abnormalities (sensitivity = 79%), while 62/80 territories without restenosis did not (specificity = 78%). In territories without a myocardial infarction (n = 48), sensitivity and specificity values were 8/8 (100%) and 36/44 (82%), and in territories with a myocardial infarction (n = 47) 7/11 (64%) and 26/36 (72%), respectively. Side branch stenosis was fairly frequent in patients without stent restenosis but with a reversible perfusion pattern on their scintiscan (8/18); however, these stenoses were induced infrequently by the stents (3 cases).CONCLUSIONUsing the criterion of defect reversibility, stress perfusion SPECT can accurately detect restenoses of coronary artery stents. This method is most accurate for evaluating patients without a previous myocardial infarction in the stented vascular territory.

Positron emission tomography (PET) represents the most advanced scintigraphic imaging technology. This technology is being employed for cardiovascular research as well as for clinical applications in patients with various cardiovascular diseases. Together with a considerable number of radiopharmaceuticals, PET allows the noninvasive assessment of myocardial perfusion, myocardial substrate metabolism, and cardiac innervation. This article will briefly review the various aspects of scintigraphic tissue characterization provided by this technology in the heart.

UNLABELLED:Misalignment between transmission and emission scans in attenuation-corrected (AC) cardiac SPECT can introduce errors of measured activity. The severity of these errors, however, has not yet been fully elucidated.METHODS:We performed a phantom measurement as well as a study of patients with low likelihood of coronary artery disease. Transmission and emission scans were acquired using a triple-head SPECT system with a collimated 241Am line source and an offset fanbeam collimator. The left ventricular myocardium was divided into five segments, and the mean regional activity was calculated for each segment using a semiquantitative polar map approach. Misalignment between transmission and emission data was created by shifting the emission data along the x, y or z axis.RESULTS:In the heart phantom, a shift between the transmission and emission data produced a decrease or increase in relative regional activity in each segment resulting in heterogeneous activity distribution. A 7-mm (1-pixel) shift produced up to 15% change in relative regional activity, suggesting that even a small misalignment between transmission and emission data can produce serious errors in measured activity. In the clinical data, the effects of misalignment were less significant than those observed in the phantom data but were still measurable and visually identifiable.CONCLUSION:The results indicate that a small misalignment between the transmission and emission data can produce serious errors in measured activity, and, thus, geometrical precision is essential for accurate diagnosis of AC SPECT images.

Objectives. This study sought to investigate changes in myocardial perfusion after direct percutaneous transluminal coronary angioplasty (PTCA) in acute myocardial infarction (MI).Background. After initially successful recanalization of the infarct-related artery, coronary-perfusion may deteriorate as a result of reocclusion, distal embolization of platelet aggregates formed at the dilated plaque or microvascular reperfusion injury. This change could offset the benefit from early intervention.Methods. The study included 19 patients in whom the infarct-related artery was successfully recanalized by PTCA with Palmaz-Schatz stent placement within 24 h after the onset of pain. Basal and papaverine-induced coronary blood flow mere assessed by Doppler flow velocity measurements and quantitative coronary angiography, In addition, basal and adenosine-induced myocardial blood how mere measured by nitrogen-13 ammonia positron emission tomography (PET).Results. Immediately after completion of the intervention, the average coronary flow reserve (CR) in the recanalized vessel was 1.56 +/- 0.51; it increased to 2.04 +/- 0.65 at 1 h (p = 0.013) and to 2.66 +/- 0.72 at 2 weeks after reperfusion (p = 0.008, n = 16). PET studies in 12 patients revealed that perfusion defect size and CR in the infarct region (2.19 +/- 0.89 vs. 2.33 +/- 0.86) did not change significantly between day 2 after recanalization and 2 weeks. However, we found significant (p < 0.03) increases in basal (by 26%) and adenosine-induced (by 40%) blood flow in the infarct region.Conclusions. Despite the persistence of a perfusion defect after successful recanalization of the occluded artery in acute MI, CR of the infarct region improves in most patients within 1 h and further improves within 2 weeks. (C) 1997 by the American College of Cardiology.

Positron emission tomography provides unique qualitative and quantitative information on myocardial perfusion, metabolism and membrane function which potentially has an important impact on diagnostic workup and treatment in patients with known or suspected coronary artery disease (CAD). CAD contributes up to one third of all deaths among persons between the ages of 35 to 60 in western countries. Risk factors and symptoms turned out to have low specificity to identify persons with the disease and thus, will not help to establish objective diagnostic workup. Assessing severity of CAD by coronary angiography and means of binary classification (disease yes/no) of morphological abnormalities, i.e. stenosis > 50%, has shown to poorly correlate with coronary blood flow and, thus, might not serve as an optimal reference standard for the disease. Cardiac PET using N-13 ammonia and Rb-82 represents a well validated and clinically usable technique for both quantitative and qualitative (semiquantitative) assessment of myocardial blood flow. However, the clinical benefit of absolute flow values for diagnosis and localisation of CAD remains controversial. Most centers rely on qualitative image interpretation due to the technical requirements for image processing needed for determination of absolute flow values. However, quantitative assessment of myocardial blood flow might offer advantages when measurement of coronary flow reserve in response to medical or interventional therapy is necessary and in addition may provide early detection of CAD in asymptomatic patients who have risk factors.