High-resolution three-dimensional MR angiography of rodent tumors: morphologic characterization of intratumoral vasculature.
OBJECTIVE
To evaluate high-resolution three-dimensional MR angiography (MRA) for the visualization and morphologic characterization of intratumoral vasculature.


METHODS
Two subcutaneous rodent tumor models (human skin carcinoma HaCaT-ras-A-5RT3 grown in nude mice and rat prostate carcinoma R3327-AT1 grown in Copenhagen rats) were examined with a clinical 1.5 T MR-system. For MRA a dedicated high-resolution three-dimensional gradient echo pulse sequence with a voxel size of 166 x 206 x 320 microm(3) was performed after injection of Gadomer-17. The image analysis included a correlation of intratumoral vessels with histology. Signal intensity measurements were performed in the vena cava, the tumor underlying muscle, and in various regions of the tumor. Signal-to-noise-ratios (SNR) and contrast-to-noise-ratios (CNR) were calculated from this measurement.


RESULTS
High-resolution MRA allowed a clear distinction of intratumoral blood vessels. The mouse tumor model tended to be strongly vascularized with several intratumoral blood vessels clearly displayed by MRA. When correlated with histology, these intratumoral blood vessels had a size in the range of 300 to 400 microm. In contrast, rat tumors had only sparse capillary intratumoral blood vessels that could only be demonstrated by histology. In both tumor models, dilated blood vessels were observed in the subcutaneous tissue near the tumor. In general, areas with a strong contrast enhancement correlated with viable, well vascularized tumor regions, whereas non-enhancing tumor areas correlated with tumor necrosis or hypoxic areas.


CONCLUSIONS
High-resolution three-dimensional MRA allows the visualization of intratumoral vasculature in rodent models. With minimal hardware and software modifications, high-resolution MRA could be performed on a clinical 1.5 T MRI scanner. Morphologic characterization of intratumoral blood vessels could add important insights into the process of tumor angiogenesis.
Fink
Christian
C
Division Oncological Diagnostics and Therapy (E010), Research Program Radiological Diagnostics and Therapy, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany. c.fink@dkfz.de
Kiessling
Fabian
F
Bock
Michael
M
Lichy
Matthias Philipp
MP
Misselwitz
Bernd
B
Peschke
Peter
P
Fusenig
Norbert E
NE
Grobholz
Rainer
R
Delorme
Stefan
S
D000818:Animals; D003287:Contrast Media; D005682:Gadolinium; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D051379:Mice; D008819:Mice, Nude; D009389:Neovascularization, Pathologic / Q000175:diagnosis*; D011471:Prostatic Neoplasms / Q000098:blood supply*; D051381:Rats; D012878:Skin Neoplasms / Q000098:blood supply*
D003287:Contrast Media; C402765:gadomer 17; D005682:Gadolinium