Image-derived input function estimation on a TOF-enabled PET/MR for cerebral blood flow mapping.
15O-H2O PET imaging is an accurate method to measure cerebral blood flow (CBF) but it requires an arterial input function (AIF). Historically, image-derived AIF estimation suffers from low temporal resolution, spill-in, and spill-over problems. Here, we optimized tracer dose on a time-of-flight PET/MR according to the acquisition-specific noise-equivalent count rate curve. An optimized dose of 850 MBq of15O-H2O was determined, which allowed sufficient counts to reconstruct a short time-frame PET angiogram (PETA) during the arterial phase. This PETA enabled the measurement of the extent of spill-over, while an MR angiogram was used to measure the true arterial volume for AIF estimation. A segment of the high cervical arteries outside the brain was chosen, where the measured spill-in effects were minimal. CBF studies were performed twice with separate [15O]-H2O injections in 10 healthy subjects, yielding values of 88 ± 16, 44 ± 9, and 58 ± 11 mL/min/100 g for gray matter, white matter, and whole brain, with intra-subject CBF differences of 5.0 ± 4.0%, 4.1 ± 3.3%, and 4.5 ± 3.7%, respectively. A third CBF measurement after the administration of 1 g of acetazolamide showed 35 ± 23%, 29 ± 20%, and 33 ± 22% increase in gray matter, white matter, and whole brain, respectively. Based on these findings, the proposed noninvasive AIF method provides robust CBF measurement with15O-H2O PET.
1 Global Applied Science Lab, GE Healthcare, Menlo Park, CA, USA.
Mohammad Mehdi
MM
Khalighi
2 PET/MR Engineering, GE Healthcare, Waukesha, WI, USA.
Timothy W
TW
Deller
3 Radiology Department, Stanford University, Stanford, CA, USA.
Audrey Peiwen
AP
Fan
3 Radiology Department, Stanford University, Stanford, CA, USA.
Praveen K
PK
Gulaka
3 Radiology Department, Stanford University, Stanford, CA, USA.
Bin
B
Shen
3 Radiology Department, Stanford University, Stanford, CA, USA.
Prachi
P
Singh
4 Molecular Imaging Program, Stanford University, Stanford, CA, USA.
Jun-Hyung
JH
Park
3 Radiology Department, Stanford University, Stanford, CA, USA.|4 Molecular Imaging Program, Stanford University, Stanford, CA, USA.
Frederick T
FT
Chin
3 Radiology Department, Stanford University, Stanford, CA, USA.|4 Molecular Imaging Program, Stanford University, Stanford, CA, USA.
Greg
G
Zaharchuk
D000328:Adult; D001921:Brain / Q000098:blood supply*; D001931:Brain Mapping / Q000379:methods*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male; D064847:Multimodal Imaging / Q000379:methods*; D049268:Positron-Emission Tomography
Image derived input function; PET/MR; cerebral blood flow; dynamic PET; time-of-flight