Relationship Between Ktrans and K1 with Simultaneous Versus Separate MR/PET in Rabbits with VX2 Tumors

Abstract

Background/aim: To compare the relationship between K_trans from DCE-MRI and K₁ from dynamic ¹³N-NH₃-PET, with simultaneous and separate MR/PET in the VX-2 rabbit carcinoma model.

Materials and methods: MR/PET was performed simultaneously and separately, 14 and 15 days after VX-2 tumor implantation at the paravertebral muscle. The K_trans and K₁ values were estimated using an in-house software program. The relationships between K_trans and K₁ were analyzed using Pearson's correlation coefficients and linear/non-linear regression function.

Results: Assuming a linear relationship, K_trans and K₁ exhibited a moderate positive correlations with both simultaneous (r=0.54-0.57) and separate (r=0.53-0.69) imaging. However, while the K_trans and K₁ from separate imaging were linearly correlated, those from simultaneous imaging exhibited a non-linear relationship. The amount of change in K₁ associated with a unit increase in K_trans varied depending on K_trans values.

Conclusion: The relationship between K_trans and K₁ may be mis-interpreted with separate MR and PET acquisition.

Keywords: 13N-NH3 PET; MR/PET; dynamic contrast enhanced-MRI; perfusion parameter; rabbit.