Influence of temporal smoothing on quantitation of left ventricular function by gated blood pool scintigraphy

Area of Science:

• Cardiovascular imaging and analysis
• Nuclear cardiology
• Medical physics

Background:

• Left ventricular (LV) function is commonly assessed using radionuclide angiography.
• LV time-activity curves are often smoothed to compute systolic and diastolic function indexes.
• Temporal smoothing may introduce systematic errors in these computations.

Purpose of the Study:

• To assess the impact of temporal smoothing on LV systolic and diastolic function indexes.
• To evaluate the effect of different smoothing levels and temporal resolutions on these indexes.
• To determine the clinical significance of smoothing-induced errors in various patient groups.

Main Methods:

• High temporal resolution (20 ms/point) LV time-activity curves were acquired in 113 normal subjects, 175 CAD patients, and 171 HCM patients.
• Curves were subjected to 0-, 3-, 5-, 7-, and 9-point temporal smoothing.
• Analysis was repeated with lower temporal resolution data (40 ms/point).

Main Results:

• Increased smoothing progressively underestimated ejection fraction (up to 5%) and peak ejection rate (up to 14%).
• Peak filling rate was more severely affected, with 9-point smoothing reducing it by up to 23% in normal subjects.
• Errors were compounded at lower temporal resolution, with peak filling rate underestimation reaching 46% in normal subjects.

Conclusions:

• Temporal smoothing of LV time-activity curves introduces significant systematic errors in LV systolic and diastolic function indexes.
• These errors are particularly pronounced with poor temporal resolution and affect peak filling and ejection rates more than ejection fraction.
• Findings are relevant to other imaging modalities like MRI and cine-CT that assess LV function from volume curves.