title: Clinical usefulness of ultrashort-lived iridium-191m from a carbon-based generator system for the evaluation of the left ventricular function.
abstract: Ultrashort-lived 191mIr (4.96 sec; 63-74 and 129 keV photons) is potentially advantageous for first-pass radionuclide angiocardiography, offering the opportunity to perform repeat studies with very low absorbed radiation dose to the patient. Left ventricular (LV) first-pass studies were performed in 72 patients with 191mIr from a new bedside 1.3 Ci (48.1 GBq) 191Os/191mIr generator system using an activated carbon support that offers high 191mIr yields (15-18%) and consistent low 191Os breakthrough (2-4 x 10(-4)%/bolus). Using a single crystal digital gamma camera, uncorrected end-diastolic counts in the left ventricular representative cycle ranged from 10 up to 30 k counts. The reproducibility of repeated LV ejection fraction (LVEF) determination at 2-min intervals in 50 patients was r = 0.97, mean diff. = 2.08 +/- 1.55 EF units. Comparison between 191mIr (80-120 mCi; 2,960-4,400 MBq) and 99mTc (20-25 mCi; 750-925 MBq) LV count rates indicates a 3 wk useful shelf life of this new generator system for cardiac studies. Iridium-191m determined LVEF correlated closely with 99mTc determined LVEF in 32 patients (r = 0.96, mean diff. = 1.87 +/- 1.23 EF units). Parametric images for LV wall motion analysis were comparable with both isotopes. We conclude that rapid, repeat, and reproducible high count rate first-pass left ventricular studies can be obtained with 191mIr from this new 191Os/191mIr generator system using a single crystal digital gamma camera.
authors.affiliation: Division of Nuclear Medicine, Middelheim Hospital, Belgium.
authors.forename: P R
authors.initials: PR
authors.lastname: Franken
authors.forename: A A
authors.initials: AA
authors.lastname: Dobbeleir
authors.forename: H R
authors.initials: HR
authors.lastname: Ham
authors.forename: C
authors.initials: C
authors.lastname: Brihaye
authors.forename: M
authors.initials: M
authors.lastname: Guillaume
authors.forename: F F
authors.initials: FF
authors.lastname: Knapp
authors.forename: J
authors.initials: J
authors.lastname: Vandevivere
mesh_terms: D000328:Adult; D000368:Aged; D003327:Coronary Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007496:Iridium Radioisotopes; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction; D011876:Radionuclide Generators; D011877:Radionuclide Imaging; D013318:Stroke Volume
chemical_list: D007496:Iridium Radioisotopes