Comparison of Gadolinium-DTPA and Macromolecular Gadolinium-DTPA-Polylysine for Contrast-Enhanced Pulmonary Time-of-Flight Magnetic Resonance Angiography

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Abstract
The authors investigated the enhancing effect of low-dose administration of the macromolecular, paramagnetic contrast medium gadolinium (Gd)-DTPA-polylysine (average molecular weight, 40,000-50,000 dalton [D]) compared with Gd-DTPA (molecular weight, 547 D) in time-of-flight magnetic resonance angiography of unilaterally damaged sheep lungs. Thirteen heart-lung preparations were examined in the head coil of a 1.5-tesla imager (Magnetom SP, Siemens, Erlangen, Germany). The authors performed time-of-flight angiograms (coronal; repetition time, 35 mseconds; echo time, 6 mseconds; 20° flip angle; pixel size 1.0 × 1.0 × 1.5 mm3) before and after application of the contrast agents. Gadolinium-DTPA-polylysine was used in a dose of 0.027 mmol/kg body weight while Gd-DTPA was injected in variable doses. After Gd-DTPA-polylysine, signal intensity increased by 118% in pulmonary arteries in healthy lungs and by 121% in damaged lungs (P CONCLUSIONS. The authors' measurements demonstrate significant improvement of time-of-flight angiograms by low-dose administration of Gd-DTPA-polylysine.