A high resolution animal PET scanner using compact PS-PMT detectors

Abstract

A new high resolution PET scanner dedicated to animal studies has been designed, built and tested. The system utilizes 240 block detectors, each of which consists of a new compact position-sensitive photomultiplier tube (PS-PMT) and an 8 x 4 BGO array. A total number of 7,680 crystals (480 per ring) are positioned to form a 508 mm diameter of 16 detector rings with 7.2 mm pitch and 114 mm axial field of view (FOV).The system is designed to perform activation studies using a monkey in a sitting position. The data can be acquired in either 2D or 3D mode, where the slice collimators are retracted in 3D mode. The transaxial resolution is 2.6 mm FWHM at the center of the FOV, and the average axial resolution on the axis of the ring is 3.3 mm FWHM in the direct slice and 3.2 mm FWHM in the cross slice. The scatter fraction, sensitivity and count rate performance were evaluated for a 10 cm diameter cylindrical phantom. The total system sensitivity is 2.3 kcps/kBq/ml in 2D mode and 22.8 kcps/kBq/ml in 3D mode. The noise equivalent count rate with 3D mode is equivalent to that with 2D mode at five times higher radioactivity level. The applicable imaging capabilities of the scanner was demonstrated by animal studies with a monkey.

PET Imaging of Ischemia-Induced Impairment of Mitochondrial Complex I Function in Monkey Brain

“…7 Furthermore, by in vivo assay in rat using small animal PET, although dose escalation study was impossible because of the lethal effects of rotenone on cardiac function, the significant reduction in uptake into the brain as well as into the heart was observed even at a relatively low dose of 0.1 mg/kg per hour. 7,8 18 F-fluoro-2-deoxy-D-glucose is useful with easier operation compared with rCBF and rCMRO 2 measurements with three consecutive measurements using very short half-life 15 O-gases. However, as shown in the present study, higher accumulation of 18 F-FDG occurred in both ROI PBR and ROI Infarct than on the Figure 2.…”

“…Positron-emitting carbon-11 ( 11 C), oxygen-15 ( 15 O), and fluorine-18 ( 18 F) were produced by 14 N(p, a) 11 C, 14 N(d, n) 15 O, and 18 O(p, n) 18 F nuclear reactions, respectively, using a cyclotron (HM-18; Sumitomo Heavy Industry, Tokyo, Japan) at Hamamatsu Photonics PET Center. Labeled compounds were synthesized using a modified CUPID system (Sumitomo Heavy Industries, Ltd., Tokyo, Japan).…”

“…After a transmission scan for 30 minutes using a 68 Ge-68 Ga rotation rod source, emission scanning with 18 F-FDG was conducted for 60 minutes, and scans with 11 C-BPR28 and 18 F-BCPP-EF were performed for 91 minutes after injection using a high-resolution animal PET scanner (SHR-7700; Hamamatsu Photonics, Hamamatsu, Japan). 15 The PET data obtained were reconstructed by the filtered back projection method with a Hanning filter of 4.5 mm full width at half maximum and attenuation correction using the transmission scan data. Individual PET and MRI images were coregistered.…”

“…The right MCA was occluded with two microvascular clips via a transorbital approach for 3 hours, and then the clips were removed from the MCA for reperfusion. 4,5 Monkeys were allowed to awaken after the scans, and they were subjected to PET measurements with 15 O-gases and 18 F-BCPP-EF 7 days (Day-7) after 3-hour MCAO ischemic insult. In addition, they were also measured with 11 C-FMZ, 11 C-PBR28, and 18 F-FDG at Day-8.…”

“…The binding properties of 18 F-BCPP-EF were assessed in an ischemic brain model of living monkey using high-resolution PET, and its cerebral uptake was compared with the regional cerebral blood flow (rCBF), regional cerebral metabolism of oxygen (rCMRO 2 ) measured with 15 O-gases, 11 C-flumazenil ( 11 C-FMZ) binding to the central-type benzodiazepine receptor (CBR), 11 C-PBR28 binding to the translocator protein, and regional cerebral blood flow (rCMRglc) measured with 18 F-FDG at Day-7/8 after 3-hour MCAO ischemic insult in the monkey brain.…”