Psychotic depression study
Please see the e-mails below in regards to the DTI sequences. I do believe David can help if you have additional questions.
Thanks! Joelle
From: Hetherington, Hoby Sent: Monday, March 09, 2015 9:23 AM To: Kincman, Joelle (Scanlon) Cc: David Rotenberg Subject: RE: DTI Scan: Changed b-vaules
Hello
We investigated this and you are correct that the B value table being used was swapped for a similar table.
To my knowledge this was not intentional and we are trying to figure out why it occurred.
One possibility is that one of the B tables when I first arrived (Jan 2013) was associated with sporadic spiking problems, which were due to the program running it and compatibility with our software. However I am not sure yet this was the issue.
terms of the newer table (more B values), this is what we use in the majority of our studies. From speaking with Claudiu, (he is the faculty member looking into this) the number of sensitizing gradients is the same and we are checking to what extent the directions are the same or give functionally the same measures.
How would you like us to proceed for March 12:
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We can most likely reinstate the old table
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We can do a head to head comparison in a couple of controls in the next day or so if you want us to validate the compatibility of the two tables.
Joby Hetherington Director MRRC Professor, Dept. of Radiology Univ. of Pittsburgh
From: Kincman, Joelle (Scanlon) Sent: Thursday, March 5, 2015 11:05 AM To: Hetherington, Hoby Cc: Kincman, Joelle (Scanlon); David Rotenberg Subject: FW: DTI Scan: Changed b-vaules
Good Morning Dr. Hetherington,
Dennis Davis had been the point person for the protocol with Dr. Ellen Whyte (PI at Pittsburgh) and Dr. Aristotle Voineskos (PI at Toronto) on the STOP-PD II Neuroimaging Study (wpc-5849).
I will defer to you for help with the issue that has been noticed (outlined in the e-mail below) on the data collected thus far. Any guidance or assistance you can provide would be greatly appreciated. Please feel free to contact me with any questions.
The next scheduled scan for the study will occur on Thursday, March 12th.
Thank you,
Joelle M. Kincman, Ph.D. Project Coordinator Sustaining Remission of Severe Depression II (STOP-PD II)
715 Bellefield Towers 100 N. Bellefield Ave. Pittsburgh, PA 15213 412-246-6012
From: David Rotenberg [mailto:djrotenberg@gmail.com] Sent: Thursday, March 05, 2015 10:44 AM To: Kincman, Joelle (Scanlon) Subject: DTI Scan: Changed b-vaules
Hi Joelle,
Hopefully we can forward this to the best person. I have observed that while some DTI scans have b=0 b-values interleaved within the scan (i.e. placed at multiple timepoints) others, particularly those acquired earlier have b=0 images at the start of the scan. Both are referred to as 60+5 however in the interleaved case there are 9.
Interleaved 9 x b=0 310025 310025_Scan2 310027 310027_Scan2 310037_Scan3 320006 320021 320021_Scan2 320022 320022_Scan2 320022_Scan3 320032 360001 360002
Start of Acquisition 5 x b=0 310010 310010_Scan2 310015 310015_Scan2 320006 320013 320013_Scan2
While interleaving the b=0 images is not necessarily an issue, my concern is whether the gradient directions are consistent between these two, and why there was a change. Secondly while having more b=0 images is not a drawback, we would need to make certain that the number of diffusion sensitizing gradients are the same and in the same directions.
I've attached the bvals and bvecs from both samples below:
Hopefully we can resolve this issue before the next scan.
Best Regards,David