32 results on '"Dudczak, Robert"'
Search Results
2. Pharmacoresistance in Epilepsy: A Pilot PET Study with the P-Glycoprotein Substrate R-[11C]verapamil
- Author
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Langer, Oliver, Bauer, Martin, Hammers, Alexander, Karch, Rudolf, Pataraia, Ekaterina, Koepp, Matthias J., Abrahim, Aiman, Luurtsema, Gert, Brunner, Martin, Sunder-Plassmann, Raute, Zimprich, Friedrich, Joukhadar, Christian, Gentzsch, Stephan, Dudczak, Robert, Kletter, Kurt, Müller, Markus, and Baumgartner, Christoph
- Published
- 2007
3. Frequency and Relevance of Elevated Calcitonin Levels in Patients with Neoplastic and Nonneoplastic Thyroid Disease and in Healthy Subjects
- Author
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Karanikas, Georgios, Moameni, Abbas, Poetzi, Christian, Zettinig, Georg, Kaserer, Klaus, Bieglmayer, Christian, Niederle, Bruno, Dudczak, Robert, and Pirich, Christian
- Published
- 2004
4. [18F]FDG-PET/CT and MRI for initial pelvic lymph node staging in patients with cervical carcinoma: The potential usefulness of [18F]FDG-PET/MRI
- Author
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Anner, Philip, primary, Mayerh�fer, Marius, additional, Wadsak, Wolfgang, additional, Geleff, Silvana, additional, Dudczak, Robert, additional, Haug, Alexander, additional, Hacker, Marcus, additional, and Karanikas, Georgios, additional
- Published
- 2018
- Full Text
- View/download PDF
5. [18F]FDG-PET/CT and MRI for initial pelvic lymph node staging in patients with cervical carcinoma: The potential usefulness of [18F]FDG-PET/MRI.
- Author
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Anner, Philip, Mayerhöfer, Marius, Wadsak, Wolfgang, Geleff, Silvana, Dudczak, Robert, Haug, Alexander, Hacker, Marcus, and Karanikas, Georgios
- Subjects
CERVICAL cancer diagnosis ,TUMOR classification ,LYMPH node cancer ,MAGNETIC resonance imaging of cancer ,CERVICAL cancer patients ,POSITRON emission tomography - Abstract
The current study aimed to determine the optimum diagnostic imaging technique out of magnetic resonance imaging (MRI),
18 F‑fludeoxyglucose positron emission tomography/computed tomography ([18 F] FDG‑PET/CT, otherwise known as PET/CT) and [18 F] FDG‑PET/MRI (otherwise known as PET/MRI) for the pelvic lymph node staging (N‑staging) of untreated cervical carcinoma (CC). A total of 27 patients were included in the present study. All patients had undergone pre‑treatment with PET/CT and MRI ≤45 days prior to undergoing a lymphadenectomy. The results from PET (separated from PET/CT), MRI and the statistically combined results of (virtual) PET/MRI were compared to those from histological analyses (the gold standard). A per‑patient‑based analysis of the detection of pelvic lymph node metastases indicated that PET/MRI had a sensitivity of 64%. The specificity of PET/CT and MRI were 69 and 62%, respectively. The positive predictive value (PPV) was 69 and 64% for PET/CT and MRI, respectively. The negative predictive value (NPV) was 64 and 62% for PET/CT and MRI, respectively. The sensitivity of the PET‑guided PET/MRI and the MRI‑guided PET/MRI was 64% for both. The specificity of the PET‑guided PET/MRI and the MRI‑guided PET/MRI was 77 and 62%, respectively. The PPV was 75% for PET‑guided PET/MRI and 64% for MRI‑guided PET/MRI, and the NPV was 67 and 62%, respectively. PET/CT and the virtual PET/MRI exhibited the same low sensitivity (64%). PET/MRI exhibited slightly better results than PET/CT regarding specificity (77 vs. 69%, respectively), PPV (75 vs. 69%, respectively) and NPV (67 vs. 64%, respectively). The results of the present study suggested that PET/CT and MRI are not optimal diagnostic modalities, and that PET/MRI does not necessarily lead to better results than PET/CT, in the pelvic N‑staging of CC. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
6. Imaging of Primitive Neuroectodermal Tumor (PNET) by Technetium-99m Tetrofosmin
- Author
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Karanikas, Georgios, Köstler, Wolfgang, Becherer, Alexander, Dudczak, Robert, Krainer, Michael, and Kletter, Kurt
- Subjects
Article Subject - Abstract
Purpose. Tc-99m tetrofosmin launched for myocardial studies has recently also shown a good detectability for several tumors. Data on PNET imaging by Tc-99m tetrofosmin are not yet available.Patient and method. In the case of a 21-year-old man suffering from pelvis PNET, Tc-99m tetrofosmin scintigraphy was performed additionally to CT and MRI.Results. The gluteal and iliac tumor masses were visualized by Tc-99m tetrofosmin according to the CT and MRI results.Discussion. Imaging with Tc-99m tetrofosmin could provide additional information to the available conventional radiological imaging modalities for diagnosis of PNET, and could be a useful tool for the restaging of the primary tumor.
- Published
- 2001
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7. Indium-lll-Labeled Platelet Scintigraphy in Carotid Atherosclerosis
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Minar, Erich, Ehringer, Herbert, Dudczak, Robert, Schöfl, Rainer, Jung, Michael, Koppensteiner, Renate, Ahmadi, R., and Kretschmer, Georg
- Published
- 1989
8. Binding kinetics of 123I[ADAM] in healthy controls: a selective SERT radioligand
- Author
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Sacher, Julia, primary, Asenbaum, Susanne, additional, Klein, Nikolas, additional, Geiss-Granadia, Thomas, additional, Mossaheb, Nilufar, additional, Poetzi, Christian, additional, Attarbaschi, Trawat, additional, Lanzenberger, Rupert, additional, Spindelegger, Christoph, additional, Rabas, Alexander, additional, Heinze, Georg, additional, Dudczak, Robert, additional, Kasper, Siegfried, additional, and Tauscher, Johannes, additional
- Published
- 2006
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9. [ 18 F]Ciprofloxacin, a New Positron Emission Tomography Tracer for Noninvasive Assessment of the Tissue Distribution and Pharmacokinetics of Ciprofloxacin in Humans
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Brunner, Martin, primary, Langer, Oliver, additional, Dobrozemsky, Georg, additional, Müller, Ulrich, additional, Zeitlinger, Markus, additional, Mitterhauser, Markus, additional, Wadsak, Wolfgang, additional, Dudczak, Robert, additional, Kletter, Kurt, additional, and Müller, Markus, additional
- Published
- 2004
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10. Clinical in vitro endothelialization of femoropopliteal bypass grafts: An actuarial follow-up over three years
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Zilla, Peter, primary, Deutsch, Manfred, additional, Meinhart, Johann, additional, Puschmann, Rudolf, additional, Eberl, Thomas, additional, Minar, Erich, additional, Dudczak, Robert, additional, Lugmaier, Herbert, additional, Schmidt, Peter, additional, Noszian, Irene, additional, and Fischlein, Teddy, additional
- Published
- 1994
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11. Effectiveness of coronary heart disease risk management in high‐risk patients
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Leitha, Thomas, primary, Staudenherz, Anton, additional, Bachmann, Bettina, additional, and Dudczak, Robert, additional
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- 1994
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12. Pharmacoresistance in Epilepsy: A Pilot PET Study with the P-Glycoprotein Substrate R-[11C]verapamil.
- Author
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Langer, Oliver, Bauer, Martin, Hammers, Alexander, Karch, Rudolf, Pataraia, Ekaterina, Koepp, Matthias J., Abrahim, Aiman, Luurtsema, Gert, Brunner, Martin, Sunder-Plassmann, Raute, Zimprich, Friedrich, Joukhadar, Christian, Gentzsch, Stephan, Dudczak, Robert, Kletter, Kurt, Müller, Markus, and Baumgartner, Christoph
- Subjects
EPILEPSY ,SEIZURES (Medicine) ,PILOT projects ,P-glycoprotein ,VERAPAMIL ,CALCIUM antagonists - Abstract
Purpose and Methods: Regional overexpression of the multidrug transporter P-glycoprotein (P-gp) in epileptic brain tissue may lower target site concentrations of antiepileptic drugs and thus contribute to pharmacoresistance in epilepsy. We used the P-gp substrate R-[
11 C]verapamil and positron emission tomography (PET) to test for differences in P-gp activity between epileptogenic and nonepileptogenic brain regions of patients with drug-resistant unilateral temporal lobe epilepsy (n = 7). We compared R-[11 C]verapamil kinetics in homologous brain volumes of interest (VOIs) located ipsilateral and contralateral to the seizure focus. Results: Among different VOIs, radioactivity was highest in the choroid plexus. The hippocampal VOI could not be used for data analysis because it was contaminated by spill-in of radioactivity from the adjacent choroid plexus. In several other temporal lobe regions that are known to be involved in seizure generation and propagation ipsilateral influx rate constants K1 and efflux rate constants k2 of R-[11 C]verapamil were descriptively increased as compared to the contralateral side. Parameter asymmetries were most prominent in parahippocampal and ambient gyrus ( K1 , range: −3.8% to +22.3%; k2 , range: −2.3% to +43.9%), amygdala ( K1 , range: −20.6% to +31.3%; k2 , range: −18.0% to +38.9%), medial anterior temporal lobe ( K1 , range: −8.3% to +14.5%; k2 , range: −14.5% to +31.0%) and lateral anterior temporal lobe ( K1 , range: −20.7% to +16.8%; k2 , range: −24.4% to +22.6%). In contrast to temporal lobe VOIs, asymmetries were minimal in a region presumably not involved in epileptogenesis located outside the temporal lobe (superior parietal gyrus, K1 , range: −3.7% to +4.5%; k2 , range: −4.2% to +5.8%). In 5 of 7 patients, ipsilateral efflux ( k2 ) increases were more pronounced than ipsilateral influx ( K1 ) increases, which resulted in ipsilateral reductions (10%–26%) of R-[11 C]verapamil distribution volumes (DV). However, for none of the examined brain regions, any of the differences in K1 , k2 and DV between the epileptogenic and the nonepileptogenic hemisphere reached statistical significance (p > 0.05, Wilcoxon matched pairs test). Conclusions: Even though we failed to detect statistically significant differences in R-[11 C]verapamil model parameters between epileptogenic and nonepileptogenic brain regions, it cannot be excluded from our pilot data in a small sample size of patients that regionally enhanced P-gp activity might contribute to drug resistance in some patients with temporal lobe epilepsy. [ABSTRACT FROM AUTHOR]- Published
- 2007
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13. The Potential Value of F-18 FDG PET in Comparison to CT in Early Prediction of Response to Imatinib (STIS71) Therapy in Patients with Gastrointestinal Stromal Tumors.
- Author
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Beheshti, Mohsen, Shuren Li, Vali, Reza, Schima, Wolfgang, Dudczak, Robert, and Langsteger, Werner
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GASTROINTESTINAL stromal tumors ,GASTROINTESTINAL tumors ,MESENCHYME ,PROTEIN-tyrosine kinases ,IMATINIB ,PRECANCEROUS conditions ,CELL fractionation ,CANCER cells ,NUCLEAR medicine - Abstract
Introduction: Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the gastrointestinal tract. GIST has been shown to over-express c-KIT (CD117), the receptor tyrosine kinase. Imatinib (STI571 or Glivec) is a new type of tyrosine kinase inhibitor that selectively inhibits various tyrosine kinases and has been successfully used to treat GIST. In this study we have compared the results of F-18 FDG PET with those of CT in patients with GIST before and early after the treatment with Imatinib. Methods: The performance of CT and FDG PET imaging in the staging and follow-up of GIST lesion was retrospectively evaluated and compared in 15 patients with 67 suspicious lesions. All patients were examined before and after treatment with Imatinib. Findings of CT and FDG PET were compared on both patient- and lesion-based basis for the whole group and for anatomic locations. Results: Overall 67 lesions were detected in both pre-therapeutic FDG PET and CT imaging. In the pre-treatment studies there was no significant difference between detected lesions on FDG PET and CT (p = 0.19). However, after treatment with Imatinib (follow-up interval of 30 ± 16 days), FDG PET predicted response to therapy earlier than CT in 18% of lesions and 14% of patients, respectively. There was no significant difference in the density of malignant lesions by means of Hounsfield unit (HU) in the baseline PET in comparison to the early post-therapeutic investigations (93 ± 16 vs. 90 ± 22). Conclusion: For treatment monitoring of Imatinib in GIST patients, FDG PET gives more precise information of active state of disease compared with CT. [ABSTRACT FROM AUTHOR]
- Published
- 2007
14. Combined PET and Microdialysis for In Vivo Assessment of Intracellular Drug Pharmacokinetics in Humans.
- Author
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Langer, Oliver, Karch, Rudolf, Müller, Ulrich, Dobrozemsky, Georg, Abrahim, Aiman, Zeitlinger, Markus, Lackner, Edith, Joukhadar, Christian, Dudczak, Robert, Kletter, Kurt, Mu¨ller, Markus, and Brunner, Martin
- Published
- 2005
15. Electromechanical Properties of Perfusion/ Metabolism Mismatch: Comparison of Nonfluoroscopic Electroanatomic Mapping with 18F-FDG PET.
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Graf, Senta, Gyöngyösi, Mariann, Khorsand, Aliasghar, Nekolla, Stephan G., Pirich, Christian, Kletter, Kurt, Dudczak, Robert, Glogar, Dietmar, Porenta, Gerold, and Sochor, Heinz
- Published
- 2004
16. Imaging of Advanced Neuroendocrine Tumors with 18F-FDOPA PET.
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Becherer, Alexander, Szabó, Monica, Karanikas, Georgios, Wunderbaldinger, Patrick, Angelberger, Peter, Raderer, Markus, Kurtaran, Amir, Dudczak, Robert, and Kletter, Kurt
- Published
- 2004
17. Model-Based Analysis of Electrocardiography-Gated Cardiac 18F-FDG PET Images to Assess Left Ventricular Geometry and Contractile Function.
- Author
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Khorsand, Aliasghar, Graf, Senta, Frank, Herbert, Kletter, Kurt, Sochor, Heinz, Maurer, Gerald, Schuster, Ernst, Globits, Sebastian, Dudczak, Robert, and Porenta, Gerold
- Published
- 2003
18. Effects of Chemotherapeutic Agents on Expression of Somatostatin Receptors in Pancreatic Tumor Cells.
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Fueger, Barbara J., Hamilton, Gerhard, Raderer, Markus, Pangerl, Thomas, Traub, Tatjana, Angelberger, Peter, Baumgartner, Gerhard, Dudczak, Robert, and Virgolini, Irene
- Published
- 2001
19. 111In-DOTA-Lanreotide Scintigraphy in Patients with Tumors of the Lung.
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Traub, Tatjana, Petkov, Ventzislav, Ofluoglu, Sedat, Pangerl, Thomas, Raderer, Markus, Fueger, Barbara J., Schima, Wolfgang, Kurtaran, Amir, Dudczak, Robert, and Virgolini, Irene
- Published
- 2001
20. [18F]Ciprofloxacin, a New Positron Emission Tomography Tracer for Noninvasive Assessment of the Tissue Distribution and Pharmacokinetics of Ciprofloxacin in Humans
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Brunner, Martin, Langer, Oliver, Dobrozemsky, Georg, Müller, Ulrich, Zeitlinger, Markus, Mitterhauser, Markus, Wadsak, Wolfgang, Dudczak, Robert, Kletter, Kurt, and Müller, Markus
- Abstract
ABSTRACTThe biodistribution and pharmacokinetics of the fluorine-18-labeled fluoroquinolone antibiotic [18F]ciprofloxacin in tissue were studied noninvasively in humans by means of positron emission tomography (PET). Special attention was paid to characterizing the distribution of [18F]ciprofloxacin to select target tissues. Healthy volunteers (n= 12) were orally pretreated for 5 days with therapeutic doses of unlabeled ciprofloxacin. On day 6, subjects received a tracer dose (mean injected amount, 700 ± 55 MBq, which contained about 0.6 mg of unlabeled ciprofloxacin) of [18F]ciprofloxacin as an intravenous bolus. Thereafter, PET imaging and venous blood sampling were initiated. Time-radioactivity curves were measured for liver, kidney, lung, heart, spleen, skeletal muscle, and brain tissues for up to 6 h after radiotracer administration. The first application of [18F]ciprofloxacin in humans has demonstrated the safety and utility of the newly developed radiotracer for pharmacokinetic PET imaging of the tissue ciprofloxacin distribution. Two different tissue compartments of radiotracer distribution could be identified. The first compartment including the kidney, heart, and spleen, from which the radiotracer was washed out relatively quickly (half-lives [t1/2s], 68, 57, and 106 min, respectively). The second compartment comprised liver, muscle, and lung tissue, which displayed prolonged radiotracer retention (t1/2, >130 min). The highest concentrations of radioactivity were measured in the liver and kidney, the main organs of excretion (standardized uptake values [SUVs], 4.9 ± 1.0 and 9.9 ± 4.4, respectively). The brain radioactivity concentrations were very low (<1 kBq · g−1) and could therefore not be quantified. Transformation of SUVs into absolute concentrations (in micrograms per milliliter) allowed us to relate the concentrations at the target site to the susceptibilities of bacterial pathogens. In this way, the frequent use of ciprofloxacin for the treatment of a variety of infections could be corroborated.
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- 2004
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21. Further Evidence for Lymphokine Overproduction in Severe Aplastic Anemia
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Hinterberger, Wolfgang, Adolf, Gunther, Aichinger, Gerald, Dudczak, Robert, Geibyler, Klaus, Hocker, Paul, Huber, Christoph, Kalhs, Peter, Knapp, Walter, Koller, Ursula, Lechner, Klaus, and Volc-Platzer, Beatrix
- Abstract
Interferon-γ (IFN-γ) and tumor necrosis factor (TNF) are lymphokines with a potent hematopoietic progenitor cell suppressive capacity. In untreated and immunosuppressed patients with severe aplastic anemia (SAA) and in control individuals we measured (a)serum levels of IFN- γ and TNF and its production by peripheral blood mononuclear cells (PBMNC); (b)serum levels of neopterin, a product that reflects endogenous IFN production; (c) resting and activated lymphocyte subpopulations; and (d)serum levels of soluble interleukin-2 receptor (IL-2R). Serum levels of IFN and TNF did not differ significantly in untreated and treated SAA patients and control individuals. Spontaneous and phytohemagglutinin-induced production of IFN and TNF by PBMNC, however, were highly increased in both untreated and treated SAA patients. Increased and decreased neopterin serum levels in untreated and treated SAA patients, respectively, suggest modulation of endogenous lymphokine release subsequent to immunosuppression. HLA-DR + antigen was mainly expressed by CD8 T cells. Circulating numbers of activated (CD4 and CDS)T cells and serum levels of IL-2R were not increased in both untreated and treated SAA patients. The proportion of HLA-DR + T cells in the PBMNC of untreated SAA patients correlated with the extent of lectin-induced IFN production. Although we were unable to confirm previous reports in SAA on (a)detectable IFN in blood and bone marrow serum, (b)improvement of stem cell growth upon neutralization of endogenous IFN, (c)absolutely increased numbers of circulating activated T cells, and (d)normalization of these abnormalities subsequent to successful immunosuppression, our data clearly support previous reports on abnormal lymphokine production in severe aplastic anemia. Our failure to relate this phenomenon to the severity of disease states, however, further raises doubts on the pathogenetic significance of lymphokine overproduction in SAA.
- Published
- 1988
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22. Glycosylated Hemoglobins (GHb): An Index of Red Cell Survival
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Panzer, Simon, Kronik, Gerhard, Bettelheim, Peter, Lechner, Klaus, Neumann, Erich, and Dudczak, Robert
- Abstract
Levels of glycosylated hemoglobins (GHb) are significantly (p < 0.0005) lower in patients with hemolytic anemia (n= 20; mean = 3.9% ± 0.1 % SD GHb of total Hb) compared to patients with nonhemolytic anemia (n= 20; mean = 7.0% ± 0.7% GHb) and normal controls (n= 30; mean = 6.7% ± 0.7% GHb). A curvilinear correlation between GHb and red cell survival is demonstrable (n= 20; r2= 0.88; p< 0.001). Determination of GHb may be useful as a screening test for hemolytic anemia and for the evaluation of the degree of hemolysis, provided that diabetes mellitus can be excluded.
- Published
- 1982
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23. [ 18 F]FDG-PET/CT and MRI for initial pelvic lymph node staging in patients with cervical carcinoma: The potential usefulness of [ 18 F]FDG-PET/MRI.
- Author
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Anner P, Mayerhöfer M, Wadsak W, Geleff S, Dudczak R, Haug A, Hacker M, and Karanikas G
- Abstract
The current study aimed to determine the optimum diagnostic imaging technique out of magnetic resonance imaging (MRI),
18 F-fludeoxyglucose positron emission tomography/computed tomography ([18 F]FDG-PET/CT, otherwise known as PET/CT) and [18 F]FDG-PET/MRI (otherwise known as PET/MRI) for the pelvic lymph node staging (N-staging) of untreated cervical carcinoma (CC). A total of 27 patients were included in the present study. All patients had undergone pre-treatment with PET/CT and MRI ≤45 days prior to undergoing a lymphadenectomy. The results from PET (separated from PET/CT), MRI and the statistically combined results of (virtual) PET/MRI were compared to those from histological analyses (the gold standard). A per-patient-based analysis of the detection of pelvic lymph node metastases indicated that PET/MRI had a sensitivity of 64%. The specificity of PET/CT and MRI were 69 and 62%, respectively. The positive predictive value (PPV) was 69 and 64% for PET/CT and MRI, respectively. The negative predictive value (NPV) was 64 and 62% for PET/CT and MRI, respectively. The sensitivity of the PET-guided PET/MRI and the MRI-guided PET/MRI was 64% for both. The specificity of the PET-guided PET/MRI and the MRI-guided PET/MRI was 77 and 62%, respectively. The PPV was 75% for PET-guided PET/MRI and 64% for MRI-guided PET/MRI, and the NPV was 67 and 62%, respectively. PET/CT and the virtual PET/MRI exhibited the same low sensitivity (64%). PET/MRI exhibited slightly better results than PET/CT regarding specificity (77 vs. 69%, respectively), PPV (75 vs. 69%, respectively) and NPV (67 vs. 64%, respectively). The results of the present study suggested that PET/CT and MRI are not optimal diagnostic modalities, and that PET/MRI does not necessarily lead to better results than PET/CT, in the pelvic N-staging of CC.- Published
- 2018
- Full Text
- View/download PDF
24. Clinical Value of 18F-fluorodihydroxyphenylalanine Positron Emission Tomography/Contrast-enhanced Computed Tomography (18F-DOPA PET/CT) in Patients with Suspected Paraganglioma.
- Author
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El-Rabadi K, Weber M, Mayerhofer M, Nakuz T, Scherer T, Mitterhauser M, Dudczak R, Hacker M, and Karanikas G
- Subjects
- Adrenal Gland Neoplasms pathology, Adult, Aged, Dihydroxyphenylalanine analogs & derivatives, False Negative Reactions, Female, Humans, Male, Middle Aged, Paraganglioma secondary, Positron Emission Tomography Computed Tomography, Radiopharmaceuticals, Sensitivity and Specificity, Young Adult, Adrenal Gland Neoplasms diagnostic imaging, Paraganglioma diagnostic imaging
- Abstract
Aim: To evaluate (18)F-fluorodihydroxyphenylalanine-positron emission tomography/ contrast-enhanced computed tomography ((18)F-DOPA PET/CT) for the detection of paragangliomas (PARA) without any patient selection, such as genetic predisposition for the development of these tumors, history of metastatic PARA or hormonal status., Patients and Methods: In this retrospective study, 28 consecutive patients (15 women, 13 men; mean age=46.4 years; age range=19-73 years), who were referred to our PET/CT center for the detection of clinically suspected PARA, were included. Final diagnosis was confirmed by histological reports of surgically proven lesions and/or clinical follow-up (including laboratory results and/or PET/CT follow-up)., Results: On a per-lesion basis (45 lesions) analysis, there was a sensitivity of 64.3% for CT, 73.8% for PET, 100% for PET/CT and a positive predictive value (PPV) of 93.1% for CT, 96.9% for PET and 100% for PET/CT. On a per-patient basis analysis, the sensitivity, specificity and accuracy for CT was 86.7%, 84.6% and 85.7%, respectively, and, for PET 80%, 100% and 89.3%, respectively, and, for PET/CT 100%., Conclusion: Based on our data, (18)F-DOPA PET/CT is a "one-stop diagnostic modality" for the assessment of patients with suspected PARA., (Copyright© 2016 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)
- Published
- 2016
25. Relevance of calcitonin cut-off in the follow-up of medullary thyroid carcinoma for conventional imaging and 18-fluorine-fluorodihydroxyphenylalanine PET.
- Author
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Sesti A, Mayerhoefer M, Weber M, Anner P, Wadsak W, Dudczak R, Haug A, and Karanikas G
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- Adult, Aged, Aged, 80 and over, Carcinoma, Medullary diagnostic imaging, Carcinoma, Medullary pathology, Female, Follow-Up Studies, Humans, Male, Middle Aged, Neoplasm Staging, Prognosis, Radionuclide Imaging, Retrospective Studies, Thyroid Neoplasms diagnostic imaging, Thyroid Neoplasms pathology, Ultrasonography, Calcitonin metabolism, Carcinoma, Medullary metabolism, Dihydroxyphenylalanine analogs & derivatives, Magnetic Resonance Imaging methods, Radiopharmaceuticals, Thyroid Neoplasms metabolism, Tomography, X-Ray Computed methods
- Abstract
Aim: The American thyroid association (ATA) recommends that additional imaging procedures supplement cervical ultrasonography (US) in any patient with a basal calcitonin value above 150 pg/ml in the follow-up of medullary thyroid carcinoma (MTC). The aim of the present study was to reaffirm or challenge this cut-off for 18-Fluorine-Fluorodihydroxyphenylalanine positron emission tomography (18F-DOPA PET) and conventional imaging ultrasonography (US), computed tomography (CT), magnetic resonance imaging (MRI))., Materials and Methods: Thirty-nine patients (18 females, 21 males), mean age 62 years, range from 35 to 86, followed-up for MTC were included in the present retrospective study. In our patients 64 18F-DOPA scans, 28 neck US, 28 CT and 8 MRI were performed. For all cases basal calcitonin values were available. Sensitivity and specificity of 18F-DOPA PET and conventional imaging (US, CT, MRI) related to calcitonin values were calculated., Results: According to the calcitonin cut-off of 150 pg/ml, we found the following sensitivities and specificities: 79% and 80% for 18F-DOPA PET, 75% and 92% for US, 80% and 25% for CT, 50% and 75% for MRI. Taking the level of detectable calcitonin, we calculated the following sensitivities: 52% for 18F-DOPA PET, 46% for US, 79% for CT and 38% for MRI., Conclusion: We cannot confirm the calcitonin cut-off proposed by the ATA for the detection of MTC recurrences and contemporaneously we cannot state that 18F-DOPA PET has a very high sensitivity. For the neck region 18F-DOPA PET and US showed similar results. 18F-DOPA PET/CT seems to be the best imaging modality for whole-body tumor detection. Bone metastases are best detected by MRI., (Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)
- Published
- 2014
26. (18)F-DOPA PET/CT and MRI: description of 12 histologically-verified pheochromocytomas.
- Author
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Magnaldi S, Mayerhoefer ME, Khameneh A, Schuetz M, Javor D, Mitterhauser M, Dudczak R, Hacker M, and Karanikas G
- Subjects
- Adult, Aged, Female, Humans, Magnetic Resonance Imaging methods, Male, Middle Aged, Multimodal Imaging methods, Positron-Emission Tomography methods, Radiopharmaceuticals, Retrospective Studies, Tomography, X-Ray Computed methods, Adrenal Gland Neoplasms diagnostic imaging, Adrenal Gland Neoplasms pathology, Dihydroxyphenylalanine analogs & derivatives, Fluorine Radioisotopes, Pheochromocytoma diagnostic imaging, Pheochromocytoma pathology
- Abstract
Aim: To describe the (18)F-fluorodihydro-xyphenylalanine ((18)F-DOPA), positron emission tomography (PET) and magnetic resonance imaging (MRI) appearance of pheochromocytomas, with a focus on the presence or absence of typical MRI features., Materials and Methods: Eleven patients with histologically-verified pheochromocytoma [sporadic (n=9), multiple endocrine neoplasia (MEN) 2A syndrome (n=2)] were enrolled retrospectively. All patients underwent an MRI examination of the upper abdomen. Nine out of 11 patients underwent (18)F-DOPA PET/CT, and the remaining two patients underwent independent PET and computed tomography (CT) examinations. (18)F-DOPA-PET/CT examinations were considered positive when an increased tracer accumulation in the adrenal region, as shown on CT images, was observed. When an adrenal mass was detected on MRI, the T1 and T2 signal intensity and contrast enhancement pattern were recorded. Based on MR characteristics, the lesions were divided into typical and atypical., Results: Ten out of 11 patients had one lesion, while one patient had two lesions. All pheochromocytomas were detected by both PET/CT and MRI. On (18)F-DOPA scans, all lesions showed an increased tracer accumulation, with a mean maximum standardized uptake value (SUVmax) of 13.7±5.75. Eight out of 12 pheochromocytomas exhibited typical MRI features, with intermediate signal intensity on T1-weighted images in-phase, absence of signal drop on T1-weighted images out-of-phase, high signal intensity on T2-weighted images, and clear contrast enhancement in the arterial phase. The remaining four lesions exhibited atypical MRI features, namely absence of one of the listed criteria., Conclusion: In the assessment of pheochromocytoma, the combination of (18)F-DOPA PET with MRI is superior to MRI-alone. (18)F-DOPA PET/MRI may yield a higher diagnostic confidence for the detection of pheochromocytoma than (18)F-DOPA PET/CT.
- Published
- 2014
27. Binding kinetics of 123I[ADAM] in healthy controls: a selective SERT radioligand.
- Author
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Sacher J, Asenbaum S, Klein N, Geiss-Granadia T, Mossaheb N, Poetzi C, Attarbaschi T, Lanzenberger R, Spindelegger C, Rabas A, Heinze G, Dudczak R, Kasper S, and Tauscher J
- Subjects
- Adult, Brain anatomy & histology, Brain diagnostic imaging, Cinanserin pharmacokinetics, Humans, Hypothalamus anatomy & histology, Hypothalamus diagnostic imaging, Magnetic Resonance Imaging, Male, Mesencephalon anatomy & histology, Mesencephalon diagnostic imaging, Protein Binding, Reproducibility of Results, Tomography, Emission-Computed, Single-Photon, Cinanserin analogs & derivatives, Radiopharmaceuticals pharmacokinetics, Serotonin Plasma Membrane Transport Proteins metabolism
- Abstract
[123I]ADAM (2-((2-((dimethylamino)methyl)phenyl)thio)-5-iodophenylamine) is a promising radioligand for in-vivo quantification of serotonin transporters (SERT) using single photon emission computed tomography (SPECT) in man. We performed tracer kinetic analysis in various brain regions to determine the optimum equilibrium time for SERT quantification with [123I]ADAM and SPECT. Radiosyntheses of [123I]ADAM were performed at MAP Medical Technologies Oy, Tikkakoski, Finland. Thirty healthy male volunteers (21-41 yr) received between 104 and 163 MBq [123I]ADAM intravenously as a bolus. Consecutively, multiple SPECT scans were performed between 14 and 420 min post-injection (p.i.) using a Siemens Multispect 3 camera. Reconstruction was performed applying filtered back projection with a Butterworth filter (cut-off 0.7, order 7) in 128x128 matrices. Regions of interest (ROI) were drawn manually on the individual T1-weighted magnetic resonance image (MRI) comprising midbrain/hypothalamus for specific binding to SERT, and the cerebellum as reference region. After re-orientation to the MRI, the ROI template was applied to SPECT studies. We generated time-activity curves for the ROI and calculated the ratio countstarget/countscerebellum minus 1 (=V3'') as a measure for specific SERT binding. Counts were corrected for applied activity, acquisition time and body-weight. Peak uptakes were observed between 14 and 50 min after bolus injection. Counts per voxel were highest in the midbrain/hypothalamus, 798 (max. 872, min. 728), whereas 462 counts per voxel (max. 599, min. 412) were measured in the cerebellum at a mean time of 31 min p.i. Stable values for V3'' reached 205-320 min p.i. Mean peak V3'' value was 1.43 (95% CI 171-230) for the midbrain/hypothalamus at 205 min p.i. [123I]ADAM is a useful ligand for in-vivo quantification of human SERT by means of SPECT, with a comparatively better signal-to-noise ratio compared to beta-CIT. Our data suggest that the acquisition time for the SPECT scan is optimally, under pseudo-equilibrium conditions, between 205-320 min post-bolus injection of the tracer.
- Published
- 2007
- Full Text
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28. T lymphocyte cytokine production patterns in hashimoto patients with elevated calcitonin levels and their relationship to tumor initiation.
- Author
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Schuetz M, Duan H, Wahl K, Pirich C, Antoni A, Kommata S, Kletter K, Dudczak R, Karanikas G, and Willheim M
- Subjects
- Adult, Aged, CD4-Positive T-Lymphocytes immunology, Female, Hashimoto Disease complications, Hashimoto Disease physiopathology, Humans, Male, Middle Aged, Thyroid Neoplasms physiopathology, Calcitonin blood, Cytokines biosynthesis, Hashimoto Disease blood, T-Lymphocytes metabolism, Thyroid Neoplasms complications
- Abstract
The aim of the study was to evaluate the possible changes in CD4+ and CD8+ T-cell cytokine production patterns in Hashimoto's thyroiditis (HT) with elevated calcitonin (CT). Fourteen consecutive patients with verified HT were included in the present study. Patients were divided into two groups. Group I: 7 HT patients with elevated CT levels (>10 pg/ml); Group II: 7 HT patients with CT levels <10 pg/ml). All patients underwent intracellular cytokine detection in CD4+ and CD8+ T-cells of peripheral blood mononuclear cells (PBMC) by flow cytometry. Patients with elevated CT levels (group I) had significantly higher percentages of CD8+ cells producing IFN-gamma compared to healthy donors. A detailed analysis of cytokine production patterns revealed that this was accompanied by an increased frequency of single IFN-gamma positive cells, i.e., cells not expressing most of the other cytokines tested. Similarly, patients in group I also showed higher percentages of CD8+ TNF-alpha positive cells than healthy donors. In this case, cells co-expressing TNF-alpha and IFN-gamma were found at significantly higher frequencies. No increase in Th1 type cytokines, such as IFN-gamma or TNF-alpha, was detectable in CD4+ T-cells. In contrast, CD4+ T-cells from group I patients showed significantly higher percentages of cells producing Th2 cytokines, such as IL-4 or IL-13. The lack of increased Th1 cytokine production accompanied by an increased Th2 cytokine production seems to be a special feature of HT patients with elevated CT levels that may reflect a pathogenetic mechanism for tumor initiation.
- Published
- 2006
29. Calcitonin measurements for early detection of medullary thyroid carcinoma or its premalignant conditions in Hashimoto's thyroiditis.
- Author
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Schuetz M, Beheshti M, Oezer S, Novotny C, Paul M, Hofmann A, Bieglmayer C, Niederle B, Kletter K, Dudczak R, Karanikas G, and Pirich C
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Carcinoma, Medullary genetics, DNA, Neoplasm blood, DNA, Neoplasm genetics, Female, Hashimoto Disease genetics, Humans, Male, Middle Aged, Precancerous Conditions genetics, Proto-Oncogene Proteins c-ret genetics, Thyroid Neoplasms genetics, Calcitonin blood, Carcinoma, Medullary blood, Hashimoto Disease blood, Precancerous Conditions blood, Thyroid Neoplasms blood
- Abstract
The measurement of basal serum calcitonin (CT) in patients with evidence of Hashimoto's thyroiditis (HT) has been proposed in a recent study demonstrating an increased prevalence of elevated basal and stimulated CT. The aim of this study was to evaluate the frequency and relevance of elevated CT levels in HT. The basal sera CT were measured in 568 consecutive HT patients using a chemiluminescent immuno-assay. Whenever the serum CT was > 10 pg/ml, a pentagastrin (PG) stimulation test was performed. Two patients with abnormal/pathological PG tests were identified. Total thyroidectomy and lymph node dissection revealed for the first patient medullary thyroid carcinoma (MTC) and for the second patient C cell hyperplasia (CCH), together with papillary thyroid carcinoma. Our data showed a low prevalence of MTC and its premalignant condition CCH in HT patients; nevertheless, the patient with MTC presented lymph node metastasis. The fact that both cases presented without evidence of nodular thyroid disease highlights the persistent diagnostic dilemma of CT screening programs.
- Published
- 2006
30. Electromechanical properties of perfusion/metabolism mismatch: comparison of nonfluoroscopic electroanatomic mapping with 18F-FDG PET.
- Author
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Graf S, Gyöngyösi M, Khorsand A, Nekolla SG, Pirich C, Kletter K, Dudczak R, Glogar D, Porenta G, and Sochor H
- Subjects
- Coronary Artery Disease diagnosis, Female, Fluoroscopy, Humans, Male, Middle Aged, Myocardial Contraction, Positron-Emission Tomography methods, Radiopharmaceuticals pharmacokinetics, Reproducibility of Results, Sensitivity and Specificity, Thallium pharmacokinetics, Coronary Artery Disease diagnostic imaging, Coronary Artery Disease physiopathology, Electrocardiography methods, Fluorodeoxyglucose F18 pharmacokinetics, Glucose metabolism, Heart Conduction System physiopathology, Myocardium metabolism
- Abstract
Unlabelled: The aim of this study was to compare nonfluoroscopic electroanatomic mapping (NOGA), SPECT perfusion imaging, and PET metabolic imaging for assessment of myocardial viability. In particular, we sought to elucidate differences of electromechanical properties between the perfusion/metabolism mismatch as an indicator of a potentially reversible ischemic injury and the perfusion/metabolism match indicating irreversibly damaged myocardial tissue., Methods: Twenty-one patients with coronary artery disease underwent NOGA mapping of endocardial unipolar voltage, cardiac 18F-FDG PET of glucose utilization, and resting 201Tl SPECT of myocardial perfusion., Results: Electrical activity was 10.8 +/- 4.6 mV (mean +/- SD) in normal myocardium and was unchanged in hypoperfused segments with maintained glucose metabolism (perfusion/metabolism mismatch), 9.3 +/- 3.4 mV (P = not significant). In contrast, hypoperfused segments with a perfusion/metabolism match and nonviable segments showed significantly lower voltage (6.9 +/- 3.1 mV, P < 0.0001 and 4.1 +/- 1.1 mV, P < 0.0001 vs. normal). In hypoperfused segments, metabolic activity was more closely related to endocardial voltage than was myocardial perfusion (201Tl vs. voltage: r = 0.38, SEE = 3.2, P < 0.001; 18F-FDG PET vs. voltage: r = 0.6, SEE = 2.8, P < 0.0001)., Conclusion: In hypoperfused myocardium, electrical activity by NOGA mapping is more closely related to PET metabolic activity than to SPECT myocardial perfusion. As NOGA mapping does not differentiate hypoperfused myocardium with enhanced glucose utilization from normal myocardium, results from NOGA mapping need to be correlated with results from perfusion imaging to identify hypoperfused, yet viable, myocardium and to stratify patients for revascularization procedures.
- Published
- 2004
31. Imaging of advanced neuroendocrine tumors with (18)F-FDOPA PET.
- Author
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Becherer A, Szabó M, Karanikas G, Wunderbaldinger P, Angelberger P, Raderer M, Kurtaran A, Dudczak R, and Kletter K
- Subjects
- Adult, Aged, Aged, 80 and over, Female, Humans, Indium Radioisotopes, Male, Middle Aged, Neuroendocrine Tumors diagnosis, Radiopharmaceuticals, Reproducibility of Results, Sensitivity and Specificity, Tomography, X-Ray Computed, Dihydroxyphenylalanine analogs & derivatives, Dihydroxyphenylalanine drug effects, Neuroendocrine Tumors diagnostic imaging, Octreotide analogs & derivatives, Tomography, Emission-Computed methods
- Abstract
Unlabelled: Nuclear medicine plays an important role in the imaging of neuroendocrine tumors (NETs). Somatostatin receptor scintigraphy (SRS) with (111)In-labeled somatostatin receptor analogs is a standard procedure for the detection and staging of NET. Based on the ability of NETs to store biogenic amines, this study evaluated whether 6-(18)F-fluoro-L-DOPA ((18)F-FDOPA) is a suitable PET tracer for NETs., Methods: Twenty-three patients with histologically verified NETs in advanced stages were consecutively enrolled in the study. All patients underwent PET with (18)F-FDOPA, CT, and SRS within 6 wk. In patients with discrepancies between nuclear medicine and radiologic methods, follow-up investigations were performed by CT, MRI, and ultrasound. (18)F-FDOPA PET with attenuation correction was done 30 and 90 min after injection from the neck to the upper legs. SRS was performed with (111)In-DOTA-D-Phe(1)-Tyr(3)-octreotide at 6 and 24 h. All images were read without knowledge of the results of the other modalities. In every patient, the following regions were evaluated separately: bones, mediastinum, lungs, liver, pancreas, and others, including the abdominal and supraclavicular lymph nodes, spleen, and soft- tissue lesions. The findings were confirmed by clinical examination. The nuclear medicine methods were compared against morphologic imaging, which was considered as gold standard., Results: The most frequently involved organs or regions were the liver (prevalence, 70%) and bone (52%), followed by mediastinal foci (31%), the lungs (22%), and the pancreas (13%). Fifty-two percent of patients had various lymphatic lesions. (18)F-FDOPA was most accurate in detecting skeletal lesions (sensitivity, 100%; specificity, 91%) but was insufficient in the lung (sensitivity, 20%; specificity, 94%); SRS yielded its best results in the liver (sensitivity, 75%; specificity, 100%); however, it was less accurate than PET in all organs. In about 40%, initial CT failed to detect bone metastases shown by PET that were later on verified by radiologic follow-up., Conclusion: (18)F-FDOPA PET performs better than SRS in visualizing NETs and may even do better than CT for bone lesions. SRS is essential to establish the usefulness of therapy with somatostatin analogs, yet is less accurate than (18)F-FDOPA PET for staging.
- Published
- 2004
32. Model-based analysis of electrocardiography-gated cardiac (18)F-FDG PET images to assess left ventricular geometry and contractile function.
- Author
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Khorsand A, Graf S, Frank H, Kletter K, Sochor H, Maurer G, Schuster E, Globits S, Dudczak R, and Porenta G
- Subjects
- Adult, Aged, Cardiac Volume, Female, Humans, Magnetic Resonance Imaging, Male, Middle Aged, Models, Biological, Electrocardiography, Fluorodeoxyglucose F18, Gated Blood-Pool Imaging, Heart diagnostic imaging, Myocardial Contraction, Tomography, Emission-Computed, Ventricular Function, Left
- Abstract
Unlabelled: This study presents and evaluates a model-based image analysis method to calculate from gated cardiac (18)F-FDG PET images diastolic and systolic volumes, ejection fraction, and myocardial mass of the left ventricle. The accuracy of these estimates was delineated using measurements obtained by MRI, which was considered the reference standard because of its high spatial resolution., Methods: Twenty patients (18 men, 2 women; mean age +/- SD, 59 +/- 12 y) underwent electrocardiography-gated cardiac PET and MRI to acquire a set of systolic and diastolic short-axis images covering the heart from apex to base. For PET images, left ventricular radius and wall thickness were estimated by model-based nonlinear regression analysis applied to the observed tracer concentration along radial rays. Endocardial and epicardial contours were derived from these estimates, and left ventricular volumes, ejection fraction, and myocardial mass were calculated. For MR images, an expert manually drew contours., Results: Left ventricular volumes by PET and MRI were 101 +/- 60 mL and 112 +/- 93 mL, respectively, for end-systolic volume and 170 +/- 68 mL and 189 +/- 99 mL, respectively, for end-diastolic volume. Ejection fraction was 44% +/- 13% by PET and 46% +/- 18% by MRI. The left ventricular mass by PET and MRI was 196 +/- 44 g and 200 +/- 46 g, respectively. PET and MRI measurements were not statistically significant. A significant correlation was observed between PET and MRI for calculation of end-systolic volumes (r = 0.93, SEE = 23.4, P < 0.0001), end-diastolic volumes (r = 0.92, SEE = 26.7, P < 0.0001), ejection fraction (r = 0.85, SEE = 7.4, P < 0.0001), and left ventricular mass (r = 0.75, SEE = 29.6, P < 0.001)., Conclusion: Model-based analysis of gated cardiac PET images permits an accurate assessment of left ventricular volumes, ejection fraction, and myocardial mass. Cardiac PET may thus offer a near-simultaneous assessment of myocardial perfusion, metabolism, and contractile function.
- Published
- 2003
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