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Examining the Results

Parameters per Study

The Parameters tab on the Gated Analysis page shows the gated results obtained for the processed gated study.

GatedAnalysisParemeters

The table lists the estimated functional metrics, namely

End Diastolic Volume (EDV)
  • Volume of the left ventricle at diastole.
  • Determined as the biggest ventricle volume in the cardiac cycle.
  • Is closely related to venous compliance.

End Systolic Volume (ESV)
  • Volume of the left ventricle at the end of contraction.
  • Determined as the smallest ventricle volume in the cardiac cycle.
  • The main factors that affect the end-systolic volume are afterload and the contractility of the heart.

Ejection fraction (EF)
  • Fraction of outbound blood pumped from the heart with each heartbeat, calculated as (EDV-ESV)/EDV.

Stroke Volume (SV)
  • Blood volume pumped from the left ventricle of the heart per beat, calculated as EDV-ESV.

Stroke Index (SI)
  • Stroke volume (SV) in relation to the body surface area (BSA), calculated as SV/BSA.

NOTE: SI is provided only if the patient height and weight are available, otherwise it is NaN. Note that these fields can be edited.

Myocardial Mass (MM)
  • Approximated by multiplying the difference of the epi- and endocardial volumes by the density of the myocardial tissue (1.04 g/cm3).

Myocardial Mass Index (MI)
  • Myocardial mass divided by the body surface area: MM/BSA.

Peak Filling Rate (PFR)
  • Most rapid change in the ventricular volume, usually occurring in the initial period of fast filling.
  • Is defined as the maximal value of the first derivative of the time-volume curve.

Time to Peak Fill Rate (TPFR)
  • Interval in milliseconds between the time of minimal ventricular volume (ESV) and the time of the determined peak filling rate (PFR).

1/3 filling rate
  • Filling rate from the time of minimal ventricular volume (ESV) to 1/3 of the total filling time.

1/3 filling fraction
  • Fraction of volume filled until 1/3 filling time.

Assessing the LV Time-Volume Curve

In the plot section the volume of left ventricle is shown as a function of time in the heart cycle. To inspect the curve in a larger window, click with the right mouse button into the curve area and select View in Separate Window from the context menu. The example below shows a typical time-volume curve.

GatedLVVolumeTimeAssessment

A time-volume curve is expected to have its minimum (end-systole) at frame 3 or 4, and its maximum (end-diastole) at frame 1 or 8 in gated acquisitions with 8 frames. Major deviations from this behavior indicate a gating failure, and the acquisition should be repeated.

Polar Plots

Polar plots are provided for the REST and STRESS studies. The example below shows the STRESS polar plot of End Systole uptake without interpolation and with the display controls disabled. An overlay showing 3 vascular territories (Arterial), 4 Sectors or 20 segments (20 AHA sectors) can be selected from the pull-down menu to right of the overlay toggle Button Polar Plot-Segments Overlay. By default, Arterial definition is used. The + button allows using an explicitly defined maximum rather than the maximum in the data, which can be specified in the adjacent number field.

GatedPolarPlot

For polar maps, the numbers in the overlay represent the average value in the territory, sector or segment.

The list selection at the bottom allows switching between the End Systole and End Diastole uptake polar maps. When the cursor is moved about the polar plot the instantaneous value is shown in the upper right.

The polar plots can be documented by the Polar Plot report. The polar plot display control can be easily switch on/off right clicking on the polar plot area and selecting the Hide/Show Controls option.

Polar Plot Properties

Activating the Properties entry in the list, display properties like Description's font size can be changed.

Visualization of the Samples found by Polar Sampling (3D Option required)

The sampling locations for the uptake measurement can be visualized together with the short axis images using the buttons

The left button enables the sampling point visualization. The right button calls the 3D tool which renders the shape of the myocardium model together with the sampling points. The example below shows the gate 8 sampling points as red spheres, the myocardium ENDO and EPI models as a wire-frame surface, and a short axis slice of the PET image with contour.

Gated3DSamplingVisualization

To learn more about the many possibilities exploring the data in P3D please refer to the PMOD 3D Rendering User Guide.