Keywords:
Experimental, MR-Diffusion/Perfusion, Colon, Gastrointestinal tract, Contrast agents, Contrast agent-intravenous, Cancer
Authors:
R. A. P. Dijkhoff1, S. drago2, J. Santinha3, D. M. J. Lambregts4, J. J. M. van Griethuysen4, F. C. Bakers1, N. Papanikolaou3, R. G. H. Beets-Tan4, M. Maas4; 1Maastricht/NL, 2MONZA/IT, 3Lisbon/PT, 4Amsterdam/NL
DOI:
10.1594/ecr2018/C-1612
Conclusion
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The aim of this study was to compare the signal intensity time curves of GDF with that of GDB in DCE-MRI in patients with rectal cancer.
In this small exploratory study,
the albumin-binding contrast agent GDF showed similar contrast uptake parameters when compared to GDB,
while the wash-out phase differed between both groups.
Our results suggest that the contrast agents behave similarly during the uptake phase. This can probably be explained by the fact that shortly after injection a large fraction of GDF is unbound and has a micromolecular size of 957 Da.
After longer exposure GDF binds to albumin,
increasing the molecular size to 68kDa.[13] Approximately 75-90% of GDF forms a complex with serum albumin [14,
16].
This leads to a plateau phase,
which really is a very slow wash-out phase.
This is contradictory with the wash-out phase in small molecular agents (e.g.
GDB) who will show quick wash-out and signal decrease,
just as we found in the 6 patients who underwent DCE-MRI with GDB.
Our study has some limitations.
First,
the sample size is small,
and it is a single centre study.
However,
this is the first study to compare the SITC of GDB with that of GDF in DCE-MRI in rectal cancer by using semiquantitative analyses.
Second,
GDF currently is unavailable for commercial use.
Third,
given the DCE acquisition time of 6 minutes,
motion could have led to possible misregistration.
In conclusion,
GDF seems to show similar contrast uptake parameters,
suggesting a similar wash-in behaviour to the micromolecular contrast agent.
GDF showed a substantially different wash-out slope than GDB due to the formation of albumin-GDF complexes later after injection.
Since GDF is not available for use in clinical practice,
the results of this study could be used to extrapolate valuable results of other studies with GDF to current clinical practice where GDB is used in DCE-MRI.