Dear Ina,
Thank you for your reply.I still have some questions about the formula of the
the relative signal enhancement.
How does the baseline signal (S_0) determined? Because it doesn't manually
enter.
I look forward to your reply.
Thank you !
Sincerely,Sharon Yu
在 2020年5月22日 星期五 下午08:46:02 [GMT+8]，
gogo850...@yahoo.com.tw<gogo850...@yahoo.com.tw> 寫道：
Dear Ina,
Thank you for your reply.I still have some questions about the formula of the
the relative signal enhancement.
How does the baseline signal (S_0) determined? Because it doesn't manually
enter.
I look forward to your reply.
Thank you !
Sincerely,Sharon Yu
在 2020年5月22日 星期五 下午04:02:46 [GMT+8]， Kompan, Ina
Nora<i.kom...@dkfz-heidelberg.de> 寫道：
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Dear Sharon,
for fitting the DCE MRI data, a Levenberg-Marquardt fitting routine is used.
The starting parameters are the initial parameters for this optimizer. So if
you set i.e. Ktrans to 15, the search for the most likely Ktrans in the
parameter space will start at this value. Setting such initial parameters can
be useful to prevent optimization resulting in local minima. This does not
mean, however, that the resulting Ktrans is constrained to values larger than
15.
Setting constraints for the resulting parameters is also possible in the box
“Constraints”. Here, the result of the optimizer is not allowed above/below the
stated upper/lower values.
Remark on the units: In MITK, Ktrans is calculated in the unit of ml/min/100ml.
You might have to do a conversion of the values, if you are using i.e. instead
ml/min/ml.
The formula of the relative signal enhancement is given by:
c(t) = k * (S(t)-S_0)/S_0,
where c(t) is the contrast agent concentration, k the conversion factor, S(t)
the dynamic DCE MRI signal, and S_0 the baseline signal.
I hope this answered your questions regarding start parameter and relative
signal enhancement? Please just let me know if something is not clear.
We will look into the DICOM reading error and get back to you on that.
Best wishes,
Ina Kompan
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