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F Helus

Publications and source records attributed to F Helus.

24 records · Page 2Linked to original sources
PubMed1980

Short-lived radionuclides for the assessment of rapid cardiovascular drug effects.

Continuous monitoring of cardiac output and sequential studies of right ventricular ejection fraction and of fractional myocardial uptake of substances with high cell affinity can be realized using 13N (t 1/2 = 9.6 min) and 81mKr (t 1/2 = 13 sec). Thus, it is possible to measure rapid changes of absolute myocardial blood flow and of the inotropic state of the right heart myocardium. This is shown in patients who underwent interventions with Dipyridamole and with Dobutamine which produce a marked increase in myocardial blood flow or cardiac dynamics, respectively.

Cardiac Output↗
PubMed1979

Ventilation studies with krypton-81m.

Nuclear medicine offers well-established methods for regional lung function assessment in the preoperative evaluation of patients with lung disease. The perfusion study with Tc-99m macroaggregates is simple and can be performed without special precautions in radiation shielding. The ventilation study with Xe-133, however, requires more elaborate apparatus as well as special procedures to collect the exhaled radioactive rare gas. Nuclear medicine departments with access to short-lived radionuclides from a nearby cyclotron can use the krypton isotope Kr-81m. The physical half-life of Kr-81m is 13 s. Its gamma energy of 190 keV is optimal for gamma cameras. Kr-81m can be used as a medical isotope in spite of its short half-life. It can be eluted with a continuously flowing gas from the generator containing the mother nuclide Rb-81 which has half-life of 4.6 h. This short half-life not only simplifies radiation protection but allows repeated studies in different projections as well. Examples of comparative studies with Xe-133 and Kr-81m are presented. The importance of taking not only anterior and posterior pictures but also lateral oblique views is stressed.

Half-Life↗