relationship between molecular tumbling rate and T2 relaxation time

[aelster]

(11-08-2018 08:37 PM)Allan Wrote:  Sorry to post in such an old thread, but I'm also a little confused about T2 dependence on "molecular tumbling" / "correlation time".

I liked the explanation of die T2 dip regarding molecular tumbling here:
https://mri-q.com/why-is-t1--t2.html

However, while browsing through the site I discovered this page:
http://mriquestions.com/bo-effect-on-t1--t2.html
with a bump near Larmor frequency.
Is this an error?

Trying to clear things up, I checked the reference (Bloembergen et.al. 1947). Adding to my confusion, Figure 14 shows a saddle, but not really a dip near Larmor frequency for T2.

thanks and best wishes,
Allan

Dear Allan,
You are quite correct and the figures are in error. The SBM equations predict only a "shoulder" or "saddle" at the resonance frequency, not a dip. I have corrected them in the last update. Thank you for drawing this to my attention. It is by careful readers/students like you that the web site keeps getting better and better.
With appreciation
Allen Elster