Factors affecting ventricular volumes determined by a count-based equilibrium method.

Published

Journal Article

Using a 99mTc-filled source ("ventricle") in an elliptical torso phantom, we analyzed the effect of source depth, region of interest (ROI) size, background concentration and source shape on volumes determined by an attenuation-corrected count-based equilibrium method. The calculated volume of a 96 cc sphere decreased linearly from 103 to 82 cc with increasing depth from 4 to 18 cm [vol = -1.48 X depth (cm) + 109, r = 0.99]. The calculated volume of the same sphere imaged at a depth of 9 cm increased from 98 to 117 cc with ROI sizes increasing from 161 to 1,369 pixels (1 pixel = 0.17 cm2). With increasing background concentration from 0-2 microCi/ml calculated volumes decreased from 95 to 85 cc (vol = -5.3 X background concentration (microCi/ml) + 95, r = 0.97). However, with correction for over-subtraction of background, increasing background activity caused no decrease in calculated volume (mean = 95 cc, s.d. = 1). Calculated volumes for the sphere and various cylinders were accurate, while those for cones were up to 37% lower for actual volumes ranging from 56-608 cc. This study demonstrates that multiple factors produce variability in count-based determination of phantom volumes. A careful consideration of the interaction of these factors with the edge-detection and computational algorithms is required.

Full Text

Duke Authors

Cited Authors

  • Fearnow, EC; Stanfield, JA; Jaszczak, RJ; Harris, CC; Coleman, RE

Published Date

  • September 1985

Published In

Volume / Issue

  • 26 / 9

Start / End Page

  • 1042 - 1047

PubMed ID

  • 2993551

Pubmed Central ID

  • 2993551

Electronic International Standard Serial Number (EISSN)

  • 1535-5667

International Standard Serial Number (ISSN)

  • 0161-5505

Language

  • eng