Hi,
I am planning to carry out infusion experiments in mice involving iodinated CT contrast agent. This application is for MRI.
Aforementioned animal experiment would require me to control and manipulate infusion curve during the course of infusion, using intravenous injection. I can use combination of bolus injection and constant infusion.
What I intend to achieve:
i) A couple of time points on infusion curve, where the concentrations are significantly different (say >40-50% at least).
ii) Since I would need approximately five minutes to acquire data, I would expect infusion curve to stay relatively flat during that time. It would be okay to have 5-10% variation; but, then I would like to have large concentration difference (100-200%) between different time point described in (i).
I would appreciate if someone could guide me.
Regards,
Dushyant Kumar
Are you performing a Iodine NMR experiment? You need to setup an infusion pump to maintain your contrast agent (assuming its something like Omnipague so rapidly cleared by mouse) concentration.
The total volume you will be able to put into the mouse will be approximately 10% blood volume. For a 25 gram mouse that is approximately 0.25 ml.
You can set your infusion rates to give yield the contrast concentration level differences between the two conditions.
What is the goal of this procedure?
Thanks,
Doug Morris
Nahrendorf et al. performed an infusion based CT study. You may want to start there. If I recall, they have a few papers using a similar approach.
Am J Physiol Heart Circ Physiol. 2007 Jun;292(6):H3172-8. Epub 2007 Feb 23.
High-resolution imaging of murine myocardial infarction with delayed-enhancement cine micro-CT.
Do you aim to image iodine infusion with CT in a specific organ? Depending on what you would like to achieve, if imaging will start at the moment of infusion, then you will be able to trace the first-pass and recirculation components in your curves, before reaching a steady state of contrast administration (infusion). This is rather typical in dynamic imaging using CT, MRI and PET. In mice, there will be enough noise and very high heart rates, you will most possible be able to dynamically trace infusion differences as mentioned above.
Dear Dr. Papanastasiou,
Thanks a lot for responding.
I am interested in infusing these contrast agent inside tumor and monitoring it using MRI based CEST imaging. I am not tracking iodine; but, amide groups that are also present. Currently I am trying in flank tumor model of the prostrate cancer. However, it seems that I may have to move to move to orthotopic model.
My objective is three fold:
i) Keep the baseline as flat as possible. However, based on your post it seems that using rat may be a better choice.
ii) To get >= 20 mM concentration inside the tumor. The conc in blood is usually 200 mM. With blood supply less developed in flank tumor model, I believe that I should move to orthotopic model.
iii) Though my knowledge about infusion is pretty limited, I believe that achieving steady state is not possible during the course of infusion. So, I would like to achieve either of these two:
- a) Either measure my data at two time points when concentrations are significantly different (more than 20-30%).
- b) or if I can justify the time course of conc inside the tumor follow some mathematical function, say bi exponential function.
Regards,
Dushyant