Small animal simultaneous PET/MRI: initial experiences in a 9.4T microMRI

Journal Article · Fri Mar 25 04:00:00 EDT 2011 · Physics in Medicine and Biology

DOI:https://doi.org/10.1088/0031-9155/56/8/009· OSTI ID:1019502

Maramraju, S H; Schlyer, D; Maramraju, S H; Smith, S D; Junnarkar, S S; Schulz, D; Stoll, S; Ravindranath, B; Purschke, M L; Rescia, S; Southekal, S; Pratte, J -F; Vaska, P; Woody, C L; Schlyer, D J

We developed a non-magnetic positron-emission tomography (PET) device based on the rat conscious animal PET that operates in a small-animal magnetic resonance imaging (MRI) scanner, thereby enabling us to carry out simultaneous PET/MRI studies. The PET detector comprises 12 detector blocks, each being a 4 x 8 array of lutetium oxyorthosilicate crystals (2.22 x 2.22 x 5 mm{sup 3}) coupled to a matching non-magnetic avalanche photodiode array. The detector blocks, housed in a plastic case, form a 38 mm inner diameter ring with an 18 mm axial extent. Custom-built MRI coils fit inside the positron-emission tomography (PET) device, operating in transceiver mode. The PET insert is integrated with a Bruker 9.4 T 210 mm clear-bore diameter MRI scanner. We acquired simultaneous PET/MR images of phantoms, of in vivo rat brain, and of cardiac-gated mouse heart using [{sup 11}C]raclopride and 2-deoxy-2-[{sup 18}F]fluoro-d-glucose PET radiotracers. There was minor interference between the PET electronics and the MRI during simultaneous operation, and small effects on the signal-to-noise ratio in the MR images in the presence of the PET, but no noticeable visual artifacts. Gradient echo and high-duty-cycle spin echo radio frequency (RF) pulses resulted in a 7% and a 28% loss in PET counts, respectively, due to high PET counts during the RF pulses that had to be gated out. The calibration of the activity concentration of PET data during MR pulsing is reproducible within less than 6%. Our initial results demonstrate the feasibility of performing simultaneous PET and MRI studies in adult rats and mice using the same PET insert in a small-bore 9.4 T MRI.

• Research Organization: BROOKHAVEN NATIONAL LABORATORY (BNL)
• Sponsoring Organization: DOE - OFFICE OF SCIENCE
• DOE Contract Number: AC02-98CH10886
• OSTI ID: 1019502
• Report Number(s): BNL--95121-2011-JA; KP1602010
• Journal Information: Physics in Medicine and Biology, Journal Name: Physics in Medicine and Biology Journal Issue: 8 Vol. 56; ISSN 0031-9155; ISSN PHMBA7
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
ADULTS
ANIMALS
BRAIN
CALIBRATION
IN VIVO
LUTETIUM
MAGNETIC RESONANCE
MICE
MRI (magnetic resonance imaging)
PET (positon emission tomography)
PET/MRI scanner
PHANTOMS
PHOTODIODES
PLASTICS
SIGNAL-TO-NOISE RATIO
SPIN ECHO
TOMOGRAPHY
animal