Angiographic properties of Gd-DTPA-24-cascade-polymer--a new macromolecular MR contrast agent.
OBJECTIVE
A new macromolecular MR contrast agent, Gd-DTPA-24-cascade-polymer, was assessed for MR angiography of peritumoral vessels in rats.


METHODS
High resolution 3D-SPGR (TR/TE 100/5ms, alpha = 90 degrees) angiograms were acquired in 10 Fischer rats bearing subcutaneous R3230 mammary adenocarcinomas. MRI was performed before, immediately and 40 min after administration of Gd-DTPA (0.1 mmol Gd/kg), and after either Gd-DTPA-cascade-polymer or albumin-(Gd-DTPA)30 (each 0.05 mmol Gd/kg). A semi-quantitative analysis of small peritumoral vessels and tumor rim enhancement was performed on maximum intensity projection (MIP) angiograms using a 4-point scoring system. A quantitative analysis compared vascular signal-to-background-(S/B), signal-to-noise-, and contrast-to-noise-ratio.


RESULTS
Gd-DTPA produced a transient and low-scoring vessel definition (0.2 +/- 0.1), but strong rim enhancement (score 1.7 +/- 0.1). The cascade polymer resulted in better but submaximal vessel delineation (score 1.6 +/- 0.3, S/B 5.0 +/- 0.2) and strong rim enhancement (score 1.8 +/- 0.1). Albumin-(Gd-DTPA)30 produced the best and most time-persistent angiograms (score 2.6 +/- 0.2, S/B 7.4 +/- 0.2), but minimal rim enhancement (score 0.3 +/- 0.2).


CONCLUSIONS
The Gd-DTPA-24-cascade-polymer demonstrated the useful combination of strong tumor rim enhancement and detailed angiographic definition of peritumoral vessels. These are advantages associated with extracellular and blood pool contrast media, respectively.
Schwickert
H C
HC
Department of Radiology, University of California, San Francisco 94143, USA.
Roberts
T P
TP
Mühler
A
A
Stiskal
M
M
Demsar
F
F
Brasch
R C
RC
D000230:Adenocarcinoma / Q000098:blood supply / Q000000981:diagnostic imaging*; D000818:Animals; D003287:Contrast Media; D005260:Female; D019786:Gadolinium DTPA; D046911:Macromolecular Substances; D018810:Magnetic Resonance Angiography; D008325:Mammary Neoplasms, Experimental / Q000098:blood supply / Q000000981:diagnostic imaging*; D009942:Organometallic Compounds; D004369:Pentetic Acid / Q000031:analogs & derivatives*; D011859:Radiography; D051381:Rats; D011916:Rats, Inbred F344
D003287:Contrast Media; D046911:Macromolecular Substances; D009942:Organometallic Compounds; C088920:gadolinium-diethylenetriaminepentaacetic acid-cascade-polymer; D004369:Pentetic Acid; D019786:Gadolinium DTPA