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Updated: Jan 31, 2026
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Evaluation of Left Ventricular Structure and Function using 3D Echocardiography
Published on: October 28, 2020
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Phase analysis, a novel SPECT technique for left ventricular dyssynchrony: Are degrees and milliseconds
Anthony J Barron1,2, Roshan Xavier3, Mohammed Al-Housni3
1Royal Brompton and Harefield NHS Trust, London, United Kingdom. anthonybarron@hotmail.co.uk.
Summary
Phase analysis in gated SPECT myocardial perfusion imaging measures left ventricular dyssynchrony. Degrees and time measurements are not interchangeable, but heart rate explains most variation, suggesting degrees may be more robust for clinical use.
Area of Science:
- Cardiology
- Nuclear Medicine
- Medical Imaging
Background:
- Gated single-photon emission computed tomography (SPECT) myocardial perfusion scintigraphy uses phase analysis to assess left ventricular dyssynchrony.
- This analysis can identify patients suitable for cardiac resynchronization therapy.
- Phase analysis is typically reported in degrees, which is less intuitive for cardiologists familiar with electrocardiograms (ECGs).
Purpose of the Study:
- To assess the relationship between time (milliseconds) and degrees in phase analysis of myocardial perfusion imaging.
- To determine if time and degree measurements are interchangeable for assessing cardiac dyssynchrony.
Main Methods:
- 399 patients with normal stress-only SPECT myocardial perfusion imaging using Technetium-99m-tetrofosmin were analyzed.
- QGS software calculated bandwidth and standard deviation.
- Heart rate, age, gender, stress modality, and ejection fraction were analyzed for their relation to phase variables.
Main Results:
- Heart rate strongly correlated with time-based measurements (bandwidth, standard deviation) but not degree-based measurements.
- Bandwidth measured in time and degrees were strongly correlated (r=0.87, P<.001) but not perfectly interchangeable.
- Heart rate explained most of the residual variation between time and degree measurements.
Conclusions:
- In patients with normal myocardial perfusion and QRS duration, phase analysis bandwidth measured in degrees is not directly interchangeable with milliseconds.
- Heart rate significantly influences time-based measurements more than degree-based measurements.
- Normal ranges for phase measured in degrees may be more robust for clinical application despite being less intuitive.
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