Comparison of gadolinium-DTPA and macromolecular gadolinium-DTPA-polylysine for contrast-enhanced pulmonary time-of-flight magnetic resonance angiography.
OBJECTIVE
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.


METHODS
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 degrees flip angle; pixel size 1.0 x 1.0 x 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.


RESULTS
After Gd-DTPA-polylysine, signal intensity increased by 118% in pulmonary arteries in healthy lungs and by 121% in damaged lungs (P < 0.001). In addition, the contrast-to-noise ratio measured between pulmonary arteries and perivascular parenchyma increased significantly (P < 0.01). On three-dimensional angiograms, two more generations of vascular branches could be detected. A dose of Gd-DTPA 6.1 times higher than the Gd-DTPA-polylysine dose was necessary to obtain the same contrast enhancing effect as Gd-DTPA-polylysine in healthy lungs. In damaged lungs, none of the administered doses of Gd-DTPA reached the average contrast enhancement of Gd-DTPA-polylysine.


CONCLUSIONS
The authors' measurements demonstrate significant improvement of time-of-flight angiograms by low-dose administration of Gd-DTPA-polylysine.
Strahlenklinik und Poliklinik, Virchow-Klinikum, Medizinische Fakultät de1 Humboldt-Universität zu Berlin, Germany.
J C
JC
Böck
F
F
Kaufmann
R
R
Felix
D000818:Animals; D003287:Contrast Media; D019786:Gadolinium DTPA; D046911:Macromolecular Substances; D018810:Magnetic Resonance Angiography / Q000379:methods*; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011107:Polylysine / Q000031:analogs & derivatives*; D011651:Pulmonary Artery / Q000473:pathology*; D011654:Pulmonary Edema / Q000473:pathology*; D012756:Sheep
D003287:Contrast Media; D046911:Macromolecular Substances; D009942:Organometallic Compounds; C068674:polylysine-(Gd-DTPA); D011107:Polylysine; D004369:Pentetic Acid; D019786:Gadolinium DTPA