Magnetic resonance imaging assessment of a convective therapy delivery paradigm in a canine prostate model.
OBJECTIVE
To quantitatively investigate the feasibility of MRI as a tool for assessing the spatial distribution of a convectively delivered agent using a canine prostate model.


METHODS
Canine prostates (ex vivo, n = 3; in vivo, n = 12) were injected under several injection paradigms with a solution of gadolinium-DTPA for MR contrast and methylene blue as a grossly visible surrogate drug marker. Ex vivo and in vivo distributions were assessed at 1.5T and quantitatively compared.


RESULTS
Measured distributions using MRI and methylene blue pathology photographs were analyzed using a Bland-Altman method. The fractional percentage volume covered (V frac) compared the measurements grossly: Pearson's correlation coefficients were R = 0.99 for ex vivo and R = 0.77 for in vivo (P < 0.05). The fractional percentage of area covered (A frac) demonstrated the high degree of spatial correlation between individual slices: R = 0.93 for ex vivo and R = 0.98 for in vivo (P < 0.05). There was no statistically observable bias in scale or offset between the measurements.


CONCLUSIONS
Measured distributions using MRI and pathology were highly correlated and unbiased, indicating the potential of MRI as a tool for quantitative assessment of interstitial delivery of injected therapies in vivo.
Shetty
Anil M
AM
Department of Imaging Physics, University of Texas MD Anderson Cancer Center, Houston, Texas 77030, USA.
Stafford
R Jason
RJ
Elliott
Andrew M
AM
Kassouf
Wassim
W
Brown
Gordon A
GA
Stephens
L Clifton
LC
Tinkey
Peggy T
PT
Bidaut
Luc
L
Pisters
Louis L
LL
Hazle
John D
JD
D000818:Animals; D003287:Contrast Media / Q000493:pharmacokinetics; D004285:Dogs; D016503:Drug Delivery Systems; D005240:Feasibility Studies; D019786:Gadolinium DTPA / Q000493:pharmacokinetics; D007267:Injections; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008751:Methylene Blue / Q000493:pharmacokinetics; D011467:Prostate / Q000378:metabolism*
D003287:Contrast Media; D019786:Gadolinium DTPA; D008751:Methylene Blue