title: Clinical value of stress-only Tc-99m SPECT imaging: importance of attenuation correction.
abstract: BACKGROUND
  In selected patients, stress-only SPECT imaging has been proposed as an alternative to rest-stress SPECT imaging to improve laboratory efficiency and reduce radiation exposure. The impact of attenuation correction (AC) upon interpretation, post-test patient management and cardiac risk stratification in relation to stress-only imaging is not well understood.
  
  
  OBJECTIVE
  The purpose of this study was to determine the clinical value for laboratory throughput and predicting outcomes of normal and abnormal stress-only SPECT imaging with AC in a consecutive series of clinically referred patients.
  
  
  METHODS
  A retrospective analysis of 1,383 consecutive patients who were scheduled for stress-only SPECT imaging for symptom assessment of suspected myocardial ischemia was performed. All images had been interpreted and categorized using the standard 17-segment model without AC followed by AC. Follow-up data for 2.1 ± 1.3 years after SPECT imaging for the occurrence of cardiac events (non-fatal MI, cardiac death, and cardiac revascularization) previously collected by routine methods were reviewed.
  
  
  RESULTS
  Non-AC SPECT image interpretation revealed that 58% (802/1383) of patients had abnormal stress images. AC image interpretation of the abnormal non-AC images re-classified 83% (666/802) of these as normal. Among patients with abnormal stress images after AC (136/1383), 63% (86/136) returned for additional rest scans, while the remaining 37% (50/136) were clinically managed without further rest images. The incidence of cardiac death or non-fatal MI was very low in patients with normal stress-only scans (0.7%).
  
  
  CONCLUSIONS
  A strategy of stress-only imaging with AC in symptomatic patients is an efficient method which appropriately identifies at risk and low-risk patients yielding a low percentage requiring rest imaging. Clinical decisions can be made based on abnormal stress-only imaging without further rest imaging if clinically appropriate.
authors.affiliation: Nuclear Cardiology Laboratory, Division of Cardiology, Henry Low Heart Center, Hartford Hospital, 80 Seymour Street, Hartford, CT 06102, USA. drshishirmathur@gmail.com
authors.forename: Shishir
authors.initials: S
authors.lastname: Mathur
authors.forename: Gary V
authors.initials: GV
authors.lastname: Heller
authors.forename: Timothy M
authors.initials: TM
authors.lastname: Bateman
authors.forename: Richard
authors.initials: R
authors.lastname: Ruffin
authors.forename: Arshad
authors.initials: A
authors.lastname: Yekta
authors.forename: Deborah
authors.initials: D
authors.lastname: Katten
authors.forename: Nitya
authors.initials: N
authors.lastname: Alluri
authors.forename: Alan W
authors.initials: AW
authors.lastname: Ahlberg
mesh_terms: D000328:Adult; D000368:Aged; D016477:Artifacts; D003324:Coronary Artery Disease / Q000175:diagnosis / Q000000981:diagnostic imaging; D020000:Decision Support Systems, Clinical; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D012815:Signal Processing, Computer-Assisted; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: D017256:Technetium Tc 99m Sestamibi