Automated quality control of emission-transmission misalignment for attenuation correction in myocardial perfusion imaging with SPECT-CT systems

J Nucl Cardiol. 2006 Jan-Feb;13(1):43-9. doi: 10.1016/j.nuclcard.2005.11.007.


Background: Emission-transmission misalignment with single-photon emission computed tomography (SPECT)-computed tomography (CT) systems can impair attenuation correction (AC) in myocardial perfusion imaging. This study was performed to develop automated quality control (Auto-QC) to detect critical misalignment that can significantly impact AC.

Methods and results: Auto-QC was developed to segment myocardium and mediastinum from emission and transmission reconstructions, respectively. Myocardium-mediastinum mismatch was used as the quality-control index (QCI). The QCI threshold for acceptable AC was determined with NCAT (NURBS [nonuniform rational B-spline]-based cardiac torso phantom) simulation and verified with 2 patients with minimal misalignment. Compromised data sets, generated by shifting the attenuation maps by 0.5, 1.0, 1.5, and 2.0 pixels along left-right, up-down, and head-foot directions, respectively, were qualitatively and quantitatively compared with the unshifted data sets. Auto-QC was tested with the 2 verification patients and 41 additional patients. Shifts by more than 1 pixel along any direction compromised AC. Auto-QC with the QCI threshold (3%) had highly concordant results with manual quality control in the detection of critical misalignment (sensitivity of 88% and 90% and specificity of 93% and 95% for the tests by use of the 2 verification patients and 41 additional patients, respectively).

Conclusion: QCI quantitatively represented the severity of misalignment. Auto-QC can help clinicians be aware of critical misalignment and can assist in realignment of SPECT and CT images.

Publication types

  • Evaluation Study

MeSH terms

  • Algorithms*
  • Artifacts*
  • Humans
  • Image Enhancement / methods*
  • Image Interpretation, Computer-Assisted / methods*
  • Phantoms, Imaging
  • Quality Assurance, Health Care / methods
  • Quality Control
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Signal Processing, Computer-Assisted
  • Subtraction Technique
  • Tomography, Emission-Computed, Single-Photon / instrumentation
  • Tomography, Emission-Computed, Single-Photon / methods*
  • Tomography, X-Ray Computed / methods*
  • Ventricular Dysfunction, Left / diagnosis*