It is a good idea to use the "Gadolinium Dose Calculator", which has been recently developed by department of Radiology, University of Wisconsin. It covers all of the gadolinium-based contrast agents approved by the U.S. Food and Drug Administration (FDA), and may be used online or as an application on your smartphone. You may find the link for the online calculator as an attachment to my answer.

https://www.radiology.wisc.edu/contrastCorner/GadCalc.php

Mohammad_Zare_Mehrjardi_ thank you but i mean the way that i can calculate image contrast induced by agent or determine what amount of agent produce that image contrast.

Dear Behrouz_Vejdani_Afkham,

The magnitude of post-contrast enhancement of both normal and pathologic tissues depends largely on the patient's hemodynamics, volume of distribution, time of image acquisition, and physiology of the tissue. Therefore, it is not possible to determine the exact dose of applied intravenous contrast material even in 2 different scans of the same patient. It is just possible to find out if there is a good amount of contrast material within the blood pool during the arterial phase if the patient has an acceptable hemodynamic condition.

In clinical practice, the required volume of intravenous contrast media is determined by the formulas that I mentioned previously (although it may be modified on occasions, e.g. for performing a double dose contrast-enhanced MRI or in a patient with renal failure). As Dr. Ben Salem mentioned, the informative parameter is presence of post-contrast enhancement within the pathologic tissue.

In addition, the kinetic of contrast agent within the desired tissue may be demonstrated by permeability imaging using dynamic contrast-enhanced MRI (DCE-MRI) technique, as well as perfusion imaging utilizing dynamic susceptibility contrast MRI (DSC-MRI) technique.

DR. Douraied_Ben_Salem

thank you for your answer but I mean susceptibility contrast ,for example between vessel and surrounding tissue .

Mohammad_Zare_Mehrjardi thank you a lot for your clear explanation but as I mentioned above my object is not weight of image .

Behrouz Vejdani Afkham

To my knowledge there are no publications on this topic.

As previously described by Mohammad Zare Mehrjardi, Gadolinium based contrast agents could not be analysed as Iodinated based contrast agents as done by Heiken et al (1995) Dynamic incremental CT: effect of volume and concentration of contrast material and patient weight on hepatic enhancement.

Therefore, you can obtain a desired enhancement (in terms of CT values) of 50HU of liver contrast enhancement in CT using the well known formula, but it is not possibile to use the same formula with Gadolinium based contrast agent.