Regional measurement of the Gd-DTPA tissue partition coefficient in canine myocardium

Quantifiable MRI perfusion studies using the contrast agent Gd-DTPA require measurement or estimation of the tissue partition coefficient (λ) for tracer kinetic modeling. Radio-tracer techniques were used to obtain regional λ measurements from the left ventricles of five dogs. Measurements were analyzed to determine whether spatial heterogeneity was a major component of λ variability. No systematic variations were identified in terms of radial position, short-axis slice location, or wall position. The high λ variability seen in this study and in cited data of others may be due in part to tissue heterogeneity in interstitial volume, plasma volume, and perfusate hematocrit.