Performance evaluation of the 32-module quadHIDAC small-animal PET scanner

© 2005 The Society of Nuclear Medicin

Multi-modality imaging of uveal melanomas using combined PET/CT, high-resolution PET and MR imaging

We investigated the efficacy of combined FDG-PET/CT imaging far the diagnosis of small-size uveal melanomas and the feasibility of combining separate, high-resolution (H R) FDG-PET with MRI far its improved localization and detection. Patients, methods: 3 patients 06 small-size uveal melanomas (0.2-1.5 ml) were imaged on a combined whole-body PET/CT, a HR brain-PET, and a 1.5 TMRI. Static, contrast-enhanced FDG-PET/CT imaging was performed of head and torso with CT contrast enhancement. HR PIT imaging was performed in dynamic mode 0-180 min post-injection of FDG. MRI imaging was performed using a high-resolution smoll-loop-coil placed over the eye in question with T2-3D-TSE and T1 -3D-SE 06 18 ml Gd-controst. Patient had their eyes shaded during the scans. Lesion visibility on high-resolution FDG-PET images was graded for confidence: 1: none, 2: suggestive, 3: clear. Mean turnout activity was calculated far summed image frames that resulted in confidence grades 2 and 3. Whole-body FDG-PET/CT images were reviewed far lesions. PET-MRI and PET/ CT-MRI images of the head were co-registered far potentiolly improved lesion delineation. Results: Whole-body FDG-PET/CT images of 3/3 patients were positive for uveal melanomas and negative for disseminated disease. HR FDG-PET was positive already in the early time homes. One patient exhibited rising tumour activity with increasing uptake time on FDG-PET. MRI images of the eye were co-registered successfully to FDG-PET/CT using a manual alignment approach. Conclusions: Small-size uveal melanomas can be detected with whole-body FDG-PET/CT. This feasibility study suggest the exploration of HR FDG-PET in order to provide additional diagnostic information on patients with uveal melanomas. First results support extended uptake times and high-sensitivity PET far improved tumour visibility. MRI/PET co-registration is feasible and provides correlated functional and anatomical information that may support alternative therapy regimens

The ECAT HRRT: NEMA NEC evaluation of the HRRT system, the new high-resolution research tomograph

Copyright 2002 by The Institute of Electrical and Electronics Engineers, Inc.The ECAT HRRT (high-resolution research tomograph) is a three- dimensional (3-D)-only dedicated brain positron emission tomograph (PET) with LSO and GSO scintillators. The system is based on eight panels of detectors. The HRRT's imaging performance has previously been tested with phantoms and FDG scans performed in animal and human brains that showed significantly improved spatial resolution, below 2.5 mm for animal studies and below 3 mm for brain studies. The NEC count rate performance has been evaluated based on the NU 2-2001 protocol. The results show a peak NEC approximately 30% higher than the performance of the Ecat HR+, this in spite of a more shallow detector for the HRRT, only 15 mm relative to the 30 mm for the HR+. However, peak NEC as derived from the 70-cm line source phantom is not optimized for the performance of dedicated brain scanner. NEC data derived with a 20-cm diameter, 20-cm long phantoms show a peak NEC more than 60% higher than for the HR+. The reasons for the high performance are due to several factors, the large axial coverage, the short timing window of 6 ns, and the low detector dead time, all factors that imply the use of fast LSO and GSO scintillators

The ECAT HRRT: Performance and first clinical application of the new high resolution research tomograph

The ECAT HRRT is a three-dimensional (3-D) only dedicated brain tomograph employing the new scintillator lutetium-oxy-orthosilicate (LSO) and using depth of interaction (DOI) information to achieve uniform isotropic resolution across a 20-cm diameter volume. With its unique technological innovations it represents the prototype of a new generation of high-resolution brain tomographs. The physical performance with respect to count rate, live time, scatter, sensitivity, and resolution was evaluated with phantom studies and measurements with a point source. The HRRTs imaging performance was tested with phantoms and fluorodeoxyglucose (FDG) scans performed in animal and human brains. We find that due to the significantly improved resolution and the large solid angle covered by the panel detectors, several Issues that have been adequately solved for older generation scanners demand new attention for the HRRT, like acquiring and handling large amounts of data effectively, strategies for optimal reconstruction, shielding, and correction of random coincidences