[Experimental evaluation of contrast medium enhanced high resolution MR angiography in the animal model. Gd-DTPA compared with Gd-DTPA-polylysine].

PURPOSE

To evaluate the qualitative and quantitative efficacy of Gd-DTPA and Gd-DTPA polylysine for contrast-enhanced high resolution MRA (CMRA) of the abdominal vessels.

MATERIALS AND METHODS

In ten anesthesized rabbits (average weight 4.3 kg) MR angiography was performed using a 1.5 T MR unit (Magnetom SP 63; Siemens Erlangen) and a CP head coil. Arterial MRA (FISP 3D TONE, TR/TE = 33/8, Flip 20 degrees) and venous MRA (FLASH 2D, TR/TE = 37/10, Flip 60 degrees) was performed before and after administration of the paramagnetic contrast agents Gd-DTPA (n = 5) or Gd-DTPA polylysine (n = 5) at a dosage of 0.1 mmol/kg. In all studies the single sections and the MIP reconstructions were evaluated quantitatively by measuring and calculating signal intensity, percentage enhancement, signal-to-noise and contrast-to-noise ratios. All studies were assessed qualitatively for visualization and distinction of the arterial and venous vessel system by three independent observers before and after the administration of contrast agent.

RESULTS

Gd-DTPA-enhanced arterial FISP 3D tone led to a percentage enhancement of 30% for the kidneys, 12% for the superior mesenteric artery, 18% for the deep circumfluent iliac artery, and 7% for the internal iliac artery. In FLASH 2D sequences Gd-DTPA led to a good C/N only for venous abdominal vessels like the left renal vein (2.59) and internal iliac vein (1.66); the percentage enhancement of these structures was between 16 and 21%. Qualitative comparison also showed no significant improvement after injection of Gd-DTPA. In FISP 3D TONE sequences Gd-DTPA polylysine led to a strong percentage enhancement of right and left kidney (21 and 40%) and deep circumfluent iliac artery (17%). Qualitative evaluation showed improved delineation and contrast of low-diameter vessels, while the soft tissue was only slightly enhanced and did not impair vessel visualization.

CONCLUSION

CMRA using Gd-DTPA and Gd-DTPA polylysine significantly improved the delineation of abdominal vessels, with Gd-DTPA polylysine being superior.