title: Low-dose thallium-201 protocol with a cadmium-zinc-telluride cardiac camera.
abstract: OBJECTIVE
  Thallium-201 is efficient for myocardial perfusion imaging, but leads to relatively high radiation exposure in patients. The purpose of this study was to compare the efficiency of low-dose thallium-201 imaging with cadmium-zinc-telluride (CZT) cameras with regular-dose thallium-201 imaging with conventional cameras.
  
  
  METHODS
  We prospectively studied 137 consecutive patients referred for stress myocardial perfusion imaging who had previously had a myocardial single-photon emission computed tomography with thallium-201. We injected at stress a low dose of thallium-201 (1.1 MBq/kg, 28 µCi/kg), performed a 5-7 min scan with a CZT camera (GE DNM 530c), and assessed redistribution imaging when the initial images were abnormal. We compared the CZT scan with the conventional dual-head tomographic camera scan taken previously with a regular dose of thallium-201.
  
  
  RESULTS
  The average delay between both scans was 22 months. The stress dose was 88 ± 16 (2.38 ± 0.43 mCi) versus 125 ± 13 MBq (3.38 ± 0.34 mCi; a 30% reduction). The time for camera acquisition was 6 versus 13 min (a 54% reduction). The myocardial counts were increased two-fold with CZT (mean: 446 Kcounts). The quality of CZT images was better in 69% of the cases. There were 59 artifacts with conventional cameras and 29 artifacts with CZT (P<0.01). The diagnostic agreement was calculated in patients without clinical or angiographic changes between both scans (115 patients) and was high (97%). The effective dose at stress was less than 12 mSv. High myocardial counting allowed for further decrease in the injected activity, leading to an effective dose as low as 8 mSv.
  
  
  CONCLUSIONS
  With reduced activities of thallium-201 and low effective doses, the CZT camera provides reliable, high-quality imaging.
authors.affiliation: North Cardiology Hospital, CCN, Saint-Denis, Paris, France. b.songy@ccncardio.com
authors.forename: Bernard
authors.initials: B
authors.lastname: Songy
authors.forename: Mohamed
authors.initials: M
authors.lastname: Guernou
authors.forename: David
authors.initials: D
authors.lastname: Lussato
authors.forename: Mathieu
authors.initials: M
authors.lastname: Queneau
authors.forename: Ricardo
authors.initials: R
authors.lastname: Geronazzo
mesh_terms: D000368:Aged; D002104:Cadmium; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000295:instrumentation*; D011446:Prospective Studies; D011829:Radiation Dosage; D015203:Reproducibility of Results; D013691:Tellurium; D013794:Thallium Radioisotopes / Q000008:administration & dosage*; D015032:Zinc
chemical_list: C474490:CdZnTe; D013794:Thallium Radioisotopes; D002104:Cadmium; D015032:Zinc; D013691:Tellurium