1. SubmillimeterfMRIAcquisition
UsingaDual-echoRosette-kspace
Trajectoryat3T
Gianna Nossa
Humberto Monsivais, Seokkyoon Hong, Taewoong Park, Fethi Sila
Erdil, Xin Shen, Ali Calgar Özen, Serhat Ilbey, Mark Chiew, Cecilia
Steinwurzel, Zoe Kourtzi, Yen-Yu Ian Shih, Uzay Emir
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2. fMRIprovides functionalconnectivityinformationinthebrain
Novel approaches have improved millimeter and submillimeter functional mapping of
cortical areas
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However, there are still limitations such as the timescale difference between neuronal
activation and blood oxygenation levels.
ADVANCES
Ø Laminar fMRI
Ø Multiband Accelerated
Ø VASO
NEURONAL ACTIVATION
Ø DIANA

3. RosetteTrajectory
EPI schemes are subject to trade-offs between spatial and temporal resolutions
§ Requires short TR and short TE
§ Efficient k-space sampling with a very short TE is needed
§ Rosette trajectory has been found to be superior
• It is fast without sacrificing resolution
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Shen X, et al. (2022)
We developed a novel Very Short TE (VSE) dual-echo
Rosette fMRI sequence to capture submillimeter fMRI
signal
GOAL: To test feasibility in vivo and compare
against multiband EPI

4. Methods
30s ON, 15s OFF visual stimulus
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2D Rosette sequence
§ TR = 2.4s
§ Dual- TEs = 1 and 9 ms
§ Slice thickness = 2mm
§ Flip Angle = 7 degrees
§ Number of slices = 1
§ Number of petals with an
acceleration factor 4 = 189
§ Nominal in-plane resolution =
0.468mm
2D CMRR Multiband-EPI
§ TR = 1.05s
§ TE = 46 ms
§ Slice thickness = 2mm
§ Flip Angle = 52 degrees
§ Number of slices = 72
§ acceleration factor = 8
§ Nominal in-plane resolution
= 1.468mm
Data Analysis
§ ESPIRiT-based parallel imaging and compressed sensing reconstruction:
• 11-wavelets in space and total variation time using BART tool
• Resolutions defined: 0.468 and 0.936mm with a 512x512 matrix
§ fMRI data processed using the FEAT tool of FSL

5. Resolution
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1st echo acquisition:
95 petals; 11ms/petal
2nd echo acquisition:
95 petals; 11ms/petal Reduced Field of View

6. Dual-EchoSequenceCapturesComparableActivationMapsintheMotorCortex
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MB-EPI
Dual-Echo
Rosette

7. Dual-EchoSequenceCapturesComparableActivationMapsandRecoversSignal
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MB-EPI
Dual-Echo
Rosette
Rosette MB-EPI

8. SubmillimeterfMRIDataisAcquiredViaDual-echoRosetteTrajectory
§ This methods has also already been tested at 7T
§ Acquisition can be tailored easily for DIANA-type
approaches
§ For future updates, check out GITHUB!
§ We are always looking for collaborators!
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This novel sequence can detect functional signals from a submillimeter
resolution (~ 0.5 mm in-plane resolution) using clinically and widely available
3T scanners

9. THANKYOU!
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