QGS Companion


Companion is a collection of enhancements to QGS.


  • Diastolic Function Assessment

Any gated short axis datasets with associated LV contours will have its diastolic function automatically computed from the time-volume curve. The following information regarding diastolic function will then be displayed:

- PER: Peak Emptying Rate (ml/s)
- PFR: Peak Filling Rate (ml/s)
- MFR/3: Mean Filling Rate for first third of cardiac cycle following end diastole (ml/s)
- TTPF: Time To Peak Filling (intervals)

A number of published reports from Japan have pointed out that diastolic function can be measured by QGS if at least 12-14 frames gating is used, and validation of all diastolic parameters has been performed

The QGS companion will display a graph showing Filling (ml/s) vs Time (cardiac intervals) as an overlay of the QGS Volume (ml) vs. Time (cardiac intervals) graph (see figure below). It will also output the various diastolic parameters¿ values, as well as the (fractional) gating interval at which they are calculated.

  • 17-segment scoring (perfusion and function)

All categorical polar maps and polar map and functional surface overlays in QGS and QPS currently available in the 20 segment format will also be made available in the AHA standard 17 segment format. Selection of the active configuration (17 or 20 segments) will be possible through a menu presented in the Defaults Dialog, so that any such change in configuration can be made both within and across application invocations. Presentation of 17 segment polar maps and polar map and functional surface overlays will be identical to those for 20 segments, with the exceptions that the 2 apex segments will be replaced with a single segment, and that the 6 most apical short axis segments will be replaced with 4 segments, as per the AHA standard.

17 segment categorical scores will be able to be automatically generated using either 17 or 20 segment using motion and thickening databases.

Summed function scores will be presented both in numerical form (SMS, STS, etc) and as a percentage of the maximal numerical values obtainable (SM%, ST%, etc). The latter are independent of the number of segments used.

  • Eccentricity index measurement

Any gated short axis datasets with associated LV contours will have the eccentricity of its mid-myocardial wall for each interval automatically computed, and expressed as an "eccentricity index". The eccentricity index of the currently displayed interval will then be displayed in the QGS Information Box as ECC, and will have values between 0 and 1 (0=sphere, 1=line). The eccentricity/sphericity of the LV is a measurement tightly related to the amount of remodeling associated with the LV.

Software Availability

Information regarding the availability of Companion can be found here.


  • Berman, D. S., X. P. Kang, et al. (2003 (abstract)). "Prognostic value of myocardial perfusion SPECT comparing 17-segment and 20-segment scoring systems." J Am Coll Cardiol 41(6(Suppl.A)): 445A.
  • Higuchi, T., K. Nakajima, et al. (2001). "Assessment of left ventricular systolic and diastolic function based on the edge detection method with myocardial ECG-gated SPECT." European Journal of Nuclear Medicine 28(10): 1512-1516.
  • Higuchi, T., J. Taki, et al. (2000 (abstract)). "Diastolic and systolic parameters obtained by myocardial ECG-gated perfusion study." J Nucl Med 41(5): 160P.
  • Kikkawa, M., T. Nakamura, et al. (2001). "Assessment of left ventricular diastolic function from quantitative electrocardiographic-gated (99)mTc-tetrofosmin myocardial SPET (ERRATA in vol 28, pg 1579, 2001)." European Journal of Nuclear Medicine 28(5): 593-601.
  • Kumita, S., K. Cho, et al. (2001). "Assessment of left ventricular diastolic function with electrocardiography-gated myocardial perfusion SPECT: Comparison with multigated equilibrium radionuclide angiography." Journal of Nuclear Cardiology 8(5): 568-574.
  • Nakajima, K., J. Taki, et al. (2001). "Diastolic dysfunction in patients with systemic sclerosis detected by gated myocardial perfusion SPECT: an early sign of cardiac involvement." Journal of Nuclear Medicine 42(2): 183-8.