 |
 |
Bumping this post up! On Fri, Jan 11, 2019 at 7:10 PM Pravesh Parekh <[log in to unmask]> wrote: > Dear All, > > I am interested in doing slice timing correction for sparse acquisitions > on a Philips Ingenia CX scanner. The experiment has a TR of 4 seconds, > acquiring 40 slices in this period. The temporal spacing between the slices > is set to minimal at the scanner console. > > As far as I know, Philips does not save slice timing information in the > DICOM header. However, we do have the "Exam card" from the scanner which is > a text file containing all the acquisition parameters. One of the values in > this file is "min. TR" which is equal to 2053 ms. This looks like the time > the scanner took to acquire these 40 slices and the rest of the TR becomes > the silent period. The slices are acquired foot to head linearly without > any slice gap. > > I have two questions: > > 1. How do I go about computing slice timing information? Simply specifying > the TR and slice order would be incorrect since the slices were not spread > out over the TR. Since we know that the per volume acquisition took 2053 > ms, would the actual slice timings be = 0:(2.053/40):2.053 (the first 40 > values)? I would also have to re-order this vector so that the last entry > corresponds to the first slice which was acquired (bottom-most). > > 2. Let's say that I specify the timing for the 20th slice (middle slice) > as the reference slice. During the first level specification, the microtime > resolution would be equal to 40 (number of slices); would it be correct to > specify the microtime onset as 20 as it requires an integer rather than > actual timing? > > > Thank you for your help > > > Regards > > Pravesh Parekh >