Dear Community,
I found this helpful discussion of [REPETITION_TIME_PREPARATION_MISSING] (RepetitionTime* parameters - what are they and where to find them? - #4 by Remi-Gau)
confirming that it is almost always equal to TR.
I am still struggling with PLD for PASL and with Bolus Cutoff Delay Time.
Neither of these values is in the DICOM header for our Siemens Skyra PASL sequence.
I have 2 examples:
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run-01: x: 1.875 mm; y: 1.875 mm; z: 4.5 mm, 6 minutes, 21 volumes, 10 CL pairs, Bolus Duration (BD) 800 ms, TI=2750 ms; TR=4
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run-02: 11 minutes, x: 1.875 mm; y: 1.875 mm; z: 4.5 mm, 41 volumes, 5 repeats of 4 CL pairs, BD=700ms, ; TR=4 and 4 PLDS (in ms): 2600, 2750, 2900, 3050 (150 ms apart):
repeat 1: pairs 1-4 use 2600, 2750, 2900, 3050
repeat 2: pairs 5-8 use 2600, 2750, 2900, 3050
repeat 3: pairs 9-12 use 2600, 2750, 2900, 3050
repeat 4: pairs 13-16 use 2600, 2750, 2900, 3050
repeat 5: pairs 17-20 use 2600, 2750, 2900, 3050
Am I correct that TI (inversion time) is equivalent to PLD for the BIDS specification? The white paper seems to define PASL PLD as TI-TI1, that is Inversion Time - Bolus Duration. For run-01 this would be 2750-800=1950 ms (For BIDS 1.95 seconds). However, the BIDS specification seems to define PLD as a longer value, e.g., PLD=TI, 2750 ms for run-01?
What is BolusCutOffDelayTime? How does it relate to BolusDuration? I’ve seen the pictures and text in the BIDS ASL specification, but I’m not sure what to make of it. Is BolusCutOffDelayTime the same as BolusDuration? Is it the same as InversionTime? Is it some kind of calculation, like TI-BD?
Any help would be greatly appreciated. Thank you!
-Dianne