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Quantitative analysis of the tomographic thallium-201 myocardial bullseye display: critical role of correcting for patient motion.
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1988
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Computed TomographyEngineeringBiomedical EngineeringPatient MotionCritical RoleQuantitative AnalysisCt ScanBiostatisticsPhoton-counting Computed TomographyCardiologyRadiologyCardiovascular ImagingVascular ImageMedical ImagingOphthalmologyImage GuidanceRadiographic ImagingPlanar ImagingBiomedical ImagingSpect Emission ImagingMedicineSingle Photon Emission
SPECT myocardial 201TI imaging offers major improvements over planar imaging, and quantitative analysis of its 3‑D data provides advantages over subjective planar methods but requires special approaches. The study developed a myocardial bullseye display to summarize and analyze 3‑D SPECT images of the left ventricle in two dimensions. The bullseye display represents each LV region as the number of standard deviations from normal, and computer programs were created to quantify vertical motion between frames, simulate non‑returning motion, and correct the data. Patient motion during the 22‑minute SPECT acquisition produced artifactual defects, with vertical shifts of 0.5–1.0 pixel causing false‑positive rates up to 40%, and such motion occurred in 10% of studies, underscoring the need for correction before reconstruction.
Single photon emission computed tomography (SPECT) myocardial 201TI imaging appears to offer major improvements over planar imaging. Quantitative analysis of the 201TI images appears to offer major advantages over subjective analysis in planar imaging, but the three-dimensional data available in SPECT images requires special approaches to analysis and display. Thus the myocardial "bullseye" display was developed to summarize and analyze the three-dimensional images of the left ventricle in two dimensions. The relative 201TI distribution to each region of the left ventricle of an individual patient can be displayed as the number of s.d.s away from normal that the region falls. We found that patient motion during the 22 min required for SPECT imaging appeared to produce artifactual defects. Thus, computer programs were developed to quantitate motion between consecutive frames of a [201TI] SPECT myocardial imaging study, simulate nonreturning vertical motion in normal patients, and correct the acquired data for motion. Motion as small as 0.5-1.0 pixel (3-6 mm) in the vertical (axial) direction caused artifactual defects in the quantitative bullseye display that resulted in a false-positive rate of up to 40% for a +1.0 pixel shift. Patient motion of magnitude greater than the threshold value for artifact-production (0.5 pixel) occurred at a rate of 10%, and should be corrected before tomographic reconstruction.