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  • 1
    Electronic Resource
    Electronic Resource
    Does Radiofrequency Catheter Ablation Induce a Deterioration in Sympathetic Innervation? A Positron Emission Tomography Study (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Pacing and clinical electrophysiology 21 (1998), S. 0 
    Details
    ISSN: 1540-8159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Radiofrequency catheter ablation (RFCA) is an effective treatment for the interruption of accessory bypass tracts in WPW syndrome or the modification of the Ay-nodal conduction system in patients with A V-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 carbons-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-I3-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 RFC A, 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 RF'CA there was no significant change observed either in ammonia or in HED distribution. Quantitative HED retention data showed no significant change before versus after RFC A. Thus, HED-PET does not demonstrate any abnormalities of tracer uptake indicating integrity of sympathetic nerve terminals after radiofrequency ablation therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1540-8159.1998.tb01115.x
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  • 2
    Electronic Resource
    Electronic Resource
    Preoperative Evaluation of Pancreatic Masses with Positron Emission Tomography Using 18F-fluorodeoxyglucose: Diagnostic Limitations (2000)
    Springer
    World journal of surgery 24 (2000), S. 1121-1129 
    Details
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Identification of pancreatic cancer in patients presenting with an enlarged pancreatic mass is a major diagnostic problem. Positron emission tomography (PET) using the radiolabeled glucose analogue 18F-fluorodeoxyglucose (FDG) has been suggested to provide excellent accuracy for noninvasive determination of suspicious pancreatic masses. We conducted a prospective study to verify these results. Forty-two patients admitted for pancreatic surgery underwent PET scanning. Image analysis was based on visual film evaluation and quantification of regional tracer uptake. PET imaging was visually analyzed by three observers blinded for the results of other diagnostic tests; they qualitatively graded the scans using a five-point scale (I = low to V = high) for the presence and intensity of focal FDG uptake. Diagnosis was proven by histology (n= 38) or follow-up (n= 4). Furthermore, the results of PET were compared with helical computed tomography (CT) and conventional ultrasonography (US), done during the routine diagnostic workup before pancreatic cancer surgery. Regarding only the results with scores of IV and V as positive for representing definite malignancy yielded a sensitivity of 71% and a specificity of 64% for film reading. Quantification of regional tracer uptake contributed no significant diagnostic advantage for differentiation between benign and malignant tumors. Helical CT revealed a sensitivity of 74% and a specificity of 45.5% and abdominal US 56% and 50%, respectively. We concluded that PET imaging provides only fair diagnostic accuracy (69%) for characterizing enlarged pancreatic masses. PET does not allow exclusion of malignant tumors. In doubtful cases, the method must be combined with other imaging modalities, such as helical CT. The results indicate that the number of invasive procedures is not significantly reduced by PET imaging.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002680010182
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  • 3
    Electronic Resource
    Electronic Resource
    Relevance of Positron Emission Tomography (PET) in Oncology (1999)
    Springer
    Strahlentherapie und Onkologie 175 (1999), S. 356-372 
    Details
    ISSN: 1439-099X
    Keywords: Key Words: Positron emission tomography ; Fluorodeoxyglucose ; Nuclear medicine ; Tumor diagnosis ; Schlüsselwörter: Positronenemissionstomographie ; Fluordeoxyglucose ; Nuklearmedizin ; Tumordiagnostik
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Hintergrund: Die Positronenemissionstomographie (PET) wird zunehmend in der Diagnostik onkologischer Erkrankungen eingesetzt. Auch in der Therapiekontrolle von Strahlen- und Chemotherapie maligner Tumoren wurde vielversprechende Ergebnisse berichtet. Methodik: Diese Übersicht beschreibt die technischen Grundlagen von PET-Untersuchungen und die biologischen Eigenschaften von Markern, die in der onkologischen Forschung und klinischen Diagnostik eingesetzt werden. Ergebnisse von in den letzten fünf Jahren in “peer-reviewed” Zeitschriften veröffentlichten klinischen Studien sind zusammengestellt, und klinische Indikationen für PET-Untersuchungen werden diskutiert. Ergebnisse und Schlußfolgerungen: In zahlreichen Studien wurde eine hohe diagnostische Genauigkeit der PET beim Nachweis und Staging maligner Tumoren unter Verwendung des Glucoseanalogons F-18-Fluordeoxyglucose (FDG) nachgewiesen. Die Anwendung der FDG-PET erwies sich als besonders erfolgreich bei Kopf-Hals-Tumoren, Bronchialkarzinomen, kolorektalen Karzinomen, malignen Melanomen und Lymphomen. Es wurde außerdem gezeigt, daß die FDG-PET bei der Differenzierung von Tumorrezidiven und therapiebedingten Veränderungen häufig der konventionellen bildgebenden Diagnostik überlegen ist. Bei der Diagnostik von Hirntumoren bieten radioaktiv markierte Aminosäuren wie C-11-Methionin aufgrund des hohen Glucosestoffwechsels der normalen grauen Stubstanz Vorteile gegenüber FDGT. Neue spezifische Marker für Tumorzellproliferation und Genexpression sind vielversprechende Ansätze für eine biologische Charakterisierung von Tumoren und Kontrolle von Therapieeffekten mittels PET.
    Notes: Background: The clinical use of positron emission tomography (PET) for detection and staging of malignant tumors is rapidly increasing. Furthermore, encouraging results for monitoring the effects of radio- and chemotherapy have been reported. Methods: This review describes the technical principles of PET and the biological characteristics of tracers used in oncological research and patient studies. The results of clinical studies published in peer reviewed journals during the last 5 years are summarized and clinical indications for PET scans in various tumor types are discussed. Results and Conclusions: Numerous studies have documented the high diagnostic accuracy of PET studies using the glucose analogue F-18-fluordeoxyglucose (FDG-PET) for detection and staging of malignant tumors. In this field, FDG-PET has been particularly successful in lung cancer, colorectal cancer, malignant lymphoma and melanoma. Furthermore, FDG-PET has often proven to be superior to morphological imaging techniques for differentiation of tumor recurrence from scar tissue. Due to the high glucose utilization of normal gray matter radiolabeled amino-acids like C-11-methionine are superior to FDG for detection and delineation of brain tumors by PET. In the future, more specific markers of tumor cell proliferation and gene expression may allow the application of PET not only for diagnostic imaging also but for non-invasive biological characterization of malignant tumors and early monitoring of therapeutic interventions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s000660050022
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  • 4
    Electronic Resource
    Electronic Resource
    Comparison of thallium-201 SPECT redistribution patterns and rubidium-82 PET rest-stress myocardial blood flow imaging (1994)
    Springer
    The international journal of cardiovascular imaging 10 (1994), S. 15-23 
    Details
    ISSN: 1573-0743
    Keywords: thallium SPECT ; rubidium PET ; myocardial perfusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract To compare regional thallium-201 SPECT redistribution patterns with rubidium-82 PET, we studied 81 patients with both imaging modalities. Sixty patients had significant coronary artery disease. All patients underwent PET imaging after dipyridamole infusion, while SPECT imaging was performed after exercise stress (38 patients) and dipyridamole (43 patients). Sixty-eight percent of patients with prior infarct had fixed defects on SPECT, compared to 39% with PET. Sixty-one percent of patients with prior infarct had PET perfusion defects which exhibited ‘reflow’ or normal rubidium-82 tracer uptake (p 〈 0.05 vs. SPECT). Similar results were seen in patients without prior infarct (26% fixed defects on SPECT vs. 12% for PET, p 〈 0.05). Regional analysis showed that 57% of fixed SPECT defects corresponded to PET defects with reflow or normal rubidium-82 uptake, while 78% of ‘fixed’ PET defects corresponded to fixed SPECT defects. PET reflow and normal rubidium-82 uptake in sites of fixed thallium-201 SPECT perfusion defects suggest that imaging modalities employing separate tracer injections at rest and after stress, such as rubidium-82 PET, may be more specific in the assessment of myocardial viability, especially in patients with prior myocardial infarction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01151577
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  • 5
    Electronic Resource
    Electronic Resource
    Imaging of myocardial autonomic innervation in patients with congestive heart failure: Methods and clinical implications (1996)
    Springer
    Heart failure reviews 1 (1996), S. 15-37 
    Details
    ISSN: 1573-7322
    Keywords: cardiac autonomic innervation ; positron emission tomography ; congestive heart failure ; 123I-MIBG SPECT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pathophysiologic role of the autonomic nervous system in the development of heart failure was recently recognized. Noninvasive imaging of cardiac autonomic innervation has become available for routine clinical diagnostic using SPECT in combination with 123I-metaiodobenzylguanidine. Positron emission tomography represents an alternative imaging modality with superior spatial resolution, allowing for sophisticated tracer approaches to various presynaptic and postsynaptic binding sites but is limited however, to few academic centers. The present review addresses the experimental and clinical experience with neuronal imaging in congestive heart failure. The clinical implications of these imaging findings are discussed. Present developments and future directions concerning the clinical application of available tracers, as well as the evaluation of new radiolabeled compounds for different sites of the autonomic nervous system and their significance for heart failure research, are presented.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00128554
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  • 6
    Electronic Resource
    Electronic Resource
    Doxorubicin cardiotoxicity: Response of left ventricular ejection fraction to exercise and incidence of regional wall motion abnormalities (1988)
    Springer
    The international journal of cardiovascular imaging 3 (1988), S. 193-201 
    Details
    ISSN: 1573-0743
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Gated radionuclide ventriculograms were performed to evaluate cardiac function in 53 patients who received doxorubicin treatment for various malignancies (mean dose: 449±128 mg/m2 BSA). In fourteen patients (Group I) function was evaluated before and after treatment; there was a significant decrease of resting left ventricular ejection fraction after therapy (p〈0.001). Twenty-two patients (Group II) had serial studies during treatment which also showed a significant fall of resting left ventricular ejection fraction (p〈0.001). Eighteen patients in Groups I and II had supine exercise studies. A normal exercise response was maintained in the majority of patients. Exercise testing added little to the diagnostic performance when compared to serial resting studies. We found regional wall motion abnormalities (mild apical hypokinesis) at rest by visual inspection in 33 of 36 Group I and Group II patients who had received doxorubicin. In the baseline or initial study, only 4 of these patients demonstrated WMA. In 18 Group I and II patients who were exercised, 3 had wall motion abnormalities during the initial study. All of these patients demonstrated wall motion abnormalities at rest after the second study, however only 7 of 18 demonstrated abnormalities during the exercise study. The results indicate that resting left ventricular ejection fraction declines after doxorubicin treatment. Exercise radionuclide angiography may not increase diagnostic accuracy for the detection of doxorubicin related cardiotoxicity. Regional wall motion abnormalities occur with a relatively high incidence following doxorubicin therapy, more readily detectable at rest. However, the exercise study can distinguish doxorubicin related wall motion abnormalities from those due to coronary artery disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01797717
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  • 7
    Electronic Resource
    Electronic Resource
    Imaging of metabolism and autonomic innervation of the heart by positron emission tomography (1992)
    Springer
    European journal of nuclear medicine 19 (1992), S. 453-464 
    Details
    ISSN: 1619-7089
    Keywords: Positron emission tomography ; Cardiac ; metabolism ; Cardiac autonomic innervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Positron emission tomography (PET) allows, in combination with multiple radiopharmaceuticals, unique physiological and biochemical tissue characterization. Tracers of blood flow, metabolism and neuronal function have been employed with this technique for research application. More recently, PET has emerged in cardiology as a useful tool for the detection of coronary artery disease and the evaluation of tissue viability. Metabolic tracers such as fluorine-18 deoxyglucose (FDG) permit the specific delineation of ischaemically compromised myocardium. Clinical studies have indicated that the metabolic imaging is helpful in selecting patients for coronary artery bypass surgery or coronary angioplasty. More recent research work has concentrated on the use of carbon-11 acetate as a marker of myocardial oxygen consumption. Together with measurements of left ventricular performance, estimates of cardiac efficiency can be derived from dynamic 11C-acetate studies. The non-invasive evaluation of the autonomic nervous system of the heart was limited in the past. With the introduction of radiopharmaceuticals which specifically bind to neuronal structures, the regional integrity of the autonomic nervous system of the heart can be evaluated with PET. Numerous tracers for pre- and postsynaptic binding sites have been synthesized. 11C-hydroxyephedrine represents a new catecholamine analogue which is stored in cardiac presynaptic sympathetic nerve terminals. Initial clinical studies with it suggest a promising role for PET in the study of the sympathetic nervous system in various cardiac diseases such as cardiomyopathy, ischaemic heart disease and diabetes mellitus. The specificity of the radiopharmaceuticals and the quantitative measurements of tissue tracer distribution provided by PET make this technology a very attractive research tool in the cardiovascular sciences with great promise in the area of cardiac metabolism and neurocardiology.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00177375
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  • 8
    Electronic Resource
    Electronic Resource
    Time course of metabolic findings in coronary occlusion and reperfusion and their role for assessing myocardial salvage (1986)
    Springer
    European journal of nuclear medicine 12 (1986), S. S54 
    Details
    ISSN: 1619-7089
    Keywords: Reperfusion ; Positron emission tomography ; Metabolic recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The techniques currently used to assess myocardial infarction are limited in their ability to determine the amount of viable myocardium after a temporary ischemic event. Blood flow and segmental function may not necessarily demonstrate salvage, whereas metabolic parameters will determine cell survival. In an open chest dog model, short occlusion times of 20 min and subsequent reperfusion using C-11 palmitate as an index of fatty acid metabolism showed depression of fatty acid oxidation, which recovered after 3 hours of reperfusion, indicating the partial reversibility of the ischemic condition. In more extensive studies, using positron emission tomography (PET) and, as an indicator of glucose metabolism, fluoro-F-18-deoxyglucose (FDG); N-13 ammonia in addition to C-11 palmitate for the determination of blood flow; and ultrasonic crystals to measure shortening in the reperfused and control territories, the duration of occlusion was 3 h. Metabolic studies were repeated 24 h, 1 week, and 4 weeks after the ischemic injury. Reperfused viable myocardium exhibited residual glucose metabolism with FDG, whereas fatty acid oxidation remained impaired for a longer period. Gradual metabolic recovery during a 4-week period was associated with the prolonged recovery of regional function, whereas a lack of residual metabolic activity indicated that little change in function was likely to occur. Increased FDG uptake and impaired C-11 palmitate turnover are characteristic of reversibly injured tissue. Therefore, PET studies may offer a unique potential for the evaluation of therapeutic measures such as thrombolysis and early revascularization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00258107
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  • 9
    Electronic Resource
    Electronic Resource
    Whole-body positron emission tomography in clinical oncology: Comparison between attenuation-corrected and uncorrected images (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 1091-1098 
    Details
    ISSN: 1619-7089
    Keywords: Whole-body positron emission tomography ; Fluorine-18 fluorodeoxyglucose ; Attenuation correction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The clinical need for attenuation correction of whole-body positron emission tomography (PET) images is controversial, especially because of the required increase in imaging time. In this study, regional tracer distribution in attenuation-corrected and uncorrected images was compared in order to delineate the potential advantages of attenuation correction for clinical application. An ECAT EXACT scanner and a protocol including five to seven bed positions, emission scans of 9 min and post-injection transmission scans of 10 min per bed position were used. Uncorrected and attenuation-corrected images were reconstructed by filtered backprojection. In total, 109 areas of focal fluorine-18 fluorodeoxyglucose (FDG) uptake in 34 patients undergoing PET for the staging of malignancies were analysed. To measure focus contrast, a ratio of focus (target) to background average countrates (t/b ratio) was obtained from transaxial slices using a region of interest technique. Calculation of focus diameters by a distance measurement tool and visual determination of focus borders were performed. In addition, images of a body phantom with spheres to simulate focal FDG uptake were acquired. Transmission scans with and without radioactivity in the phantom were used with increasing transmission scanning times (2–30 min). The t/b ratios of the spheres were calculated and compared for the different imaging protocols. In patients, the t/b ratio was significantly higher for uncorrected images than for attenuation-corrected images (5.0±3.6 vs 3.1±1.4;P〈0.001). This effect was independent of focus localization, tissue type and distance to body surface. Compared with the attenuation-corrected images, foci in uncorrected images showed larger diameters in the anterior-posterior dimension (27±14 vs 23±12 mm;P〈0.001) but smaller diameters in the leftright dimension (19±11 vs 21±11 mm;P〈0.001). Phantom data confirmed higher contrast in uncorrected images compared with attenuation-corrected images. It is concluded that, although distortion of foci was demonstrated, uncorrected images provided higher contrast for focal FDG uptake independent of tumour localization. In most clinical situations, the main issue of whole-body PET is pure lesion detection with the highest contrast possible, and not quantification of tracer uptake. The present data suggest that attenuation correction may not be necessary for this purpose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01254239
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  • 10
    Electronic Resource
    Electronic Resource
    Whole-body positron emission tomography in clinical oncology: comparison between attenuation-corrected and uncorrected images (1997)
    Springer
    European journal of nuclear medicine 24 (1997), S. 1091-1098 
    Details
    ISSN: 1619-7089
    Keywords: Key words: Whole-body positron emission tomography ; Fluorine-18 fluorodeoxyglucose ; Attenuation correction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. The clinical need for attenuation correction of whole-body positron emission tomography (PET) images is controversial, especially because of the required increase in imaging time. In this study, regional tracer distribution in attenuation-corrected and uncorrected images was compared in order to delineate the potential advantages of attenuation correction for clinical application. An ECAT EXACT scanner and a protocol including five to seven bed positions, emission scans of 9 min and post-injection transmission scans of 10 min per bed position were used. Uncorrected and attenuation-corrected images were reconstructed by filtered backprojection. In total, 109 areas of focal fluorine-18 fluorodeoxyglucose (FDG) uptake in 34 patients undergoing PET for the staging of malignancies were analysed. To measure focus contrast, a ratio of focus (target) to background average countrates (t/b ratio) was obtained from transaxial slices using a region of interest technique. Calculation of focus diameters by a distance measurement tool and visual determination of focus borders were performed. In addition, images of a body phantom with spheres to simulate focal FDG uptake were acquired. Transmission scans with and without radioactivity in the phantom were used with increasing transmission scanning times (2–30 min). The t/b ratios of the spheres were calculated and compared for the different imaging protocols. In patients, the t/b ratio was significantly higher for uncorrected images than for attenuation-corrected images (5.0±3.6 vs 3.1±1.4; P〈0.001). This effect was independent of focus localization, tissue type and distance to body surface. Compared with the attenuation-corrected images, foci in uncorrected images showed larger diameters in the anterior-posterior dimension (27±14 vs 23±12 mm; P〈0.001) but smaller diameters in the left-right dimension (19±11 vs 21±11 mm; P〈0.001). Phantom data confirmed higher contrast in uncorrected images compared with attenuation-corrected images. It is concluded that, although distortion of foci was demonstrated, uncorrected images provided higher contrast for focal FDG uptake independent of tumour localization. In most clinical situations, the main issue of whole-body PET is pure lesion detection with the highest contrast possible, and not quantification of tracer uptake. The present data suggest that attenuation correction may not be necessary for this purpose.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01254239
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