Dynamic contrast-enhanced magnetic resonance imaging of human melanoma xenografts with necrotic regions.
OBJECTIVE
To investigate whether high-resolution images of necrotic regions in tumors can be derived from gadopentetate dimeglumine (Gd-DTPA)-based dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) series.


METHODS
E-13 human melanoma xenografts were used as preclinical models of human cancer. DCE-MRI was performed at a voxel size of 0.23 x 0.47 x 2.0 mm3 with the use of spoiled gradient recalled sequences. Tumor images of E . F (E is the initial extraction fraction of Gd-DTPA and F is blood perfusion) and lambda (the partition coefficient of Gd-DTPA, which is proportional to extracellular volume fraction) were produced by subjecting DCE-MRI series to Kety analysis, and these images were compared with histological preparations from the imaged slices.


RESULTS
Strong correlations were found between fraction of necrotic tissue and fraction of voxels with lambda > lambdaL for lambdaL values of 0.4 to 0.6. Binary lambda images differentiating between lambda values > lambdaL and lambda values < lambdaL were found to mirror necrotic regions well in tumors with large necroses. However, necrotic foci that were small compared with the voxel size were not detectable.


CONCLUSIONS
Clinically relevant images of necrotic tumor regions can be obtained for E-13 melanomas by subjecting Gd-DTPA-based DCE-MRI series to Kety analysis.
Gaustad
Jon-Vidar
JV
Group of Radiation Biology and Tumor Physiology, Department of Radiation Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo, Norway.
Benjaminsen
Ilana C
IC
Ruud
Else-Beate M
EB
Rofstad
Einar K
EK
D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis; D003287:Contrast Media / Q000493:pharmacokinetics; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007124:Immunoenzyme Techniques; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008546:Melanoma, Experimental / Q000098:blood supply*; D051379:Mice; D008807:Mice, Inbred BALB C; D009336:Necrosis; D014183:Transplantation, Heterologous
D014408:Biomarkers, Tumor; D003287:Contrast Media; D019786:Gadolinium DTPA