T2*-relaxivity contrast imaging: first results.
In this study, T2*- relaxivity contrast imaging (RCI) is proposed for new contrast generation in MRI. The method produces images of relaxivities r*2,vasc and r*2,EES caused by susceptibility gradients across the vessel walls and cell membranes, respectively. The sensitivity to noise was assessed with a simulation study, and initial results are presented for five colorectal tumor xenografts in nude mice. Simulations show that the new relaxivity parameters are at least as accurate and precise as standard parameters such as plasma volume and interstitial volume. Mean values of both relaxivities were significantly different (r*2,vasc=10.9±2.9 mM(-1) s(-1) and r*2,EES=15.6±2.6 mM(-1) s(-1)). r*2,vasc (r=0.67) and r*2,EES (r=0.52) were weakly correlated with plasma volume and interstitial volume, respectively. Images of r*2,vasc and r*2,EES reveal a different tumor structure than plasma volume and interstitial volume maps. These results suggest that relaxivity contrast imaging is practically feasible and might offer supplementary information compared to dynamic contrast-enhanced-MRI.
Division of Medical Physics, University of Leeds, United Kingdom. s.sourbron@leeds.ac.uk
Steven
S
Sourbron
Melanie
M
Heilmann
Christine
C
Walczak
Julien
J
Vautier
Lothar R
LR
Schad
Andreas
A
Volk
D000465:Algorithms; D000818:Animals; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000175:diagnosis* / Q000378:metabolism*; D003198:Computer Simulation; D003287:Contrast Media / Q000493:pharmacokinetics; D006571:Heterocyclic Compounds / Q000493:pharmacokinetics*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D008954:Models, Biological; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D010865:Pilot Projects; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media; D006571:Heterocyclic Compounds; D009942:Organometallic Compounds; C435266:contrast agent P792