European journal of nuclear medicine and molecular imaging
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Eur. J. Nucl. Med. Mol. Imaging · Jun 2004
Comparative Study Clinical Trial Controlled Clinical TrialUse of a standardized uptake value for parametric in vivo imaging of benzodiazepine receptor distribution on [11C]flumazenil brain PET.
To simplify the acquisition protocol of carbon-11 labeled flumazenil (FMZ) positron emission tomography (PET) for distribution volume (DV) images, we attempted to obtain standardized uptake value (SUV) images compatible with DV images, and assessed the applicability of this method in patients with unilateral cerebrovascular diseases (CVD). [(11)C]FMZ PET was performed in ten normal subjects. A DV image and ten sequential 5-min SUV images were generated for each subject. We investigated the correlation coefficient (r) and standard estimation of error (SEE) between the latter ten static images and the DV image using the pixel-by-pixel method, thereby determining the optimum acquisition phase. ⋯ A high r (0.945) and a low SEE (0.0438) between the DV L/N ratio and the SUV L/N ratio were obtained in the study of patients. Our study suggests that SUV images acquired from 30 to 35 min after FMZ administration are a suitable alternative to DV images not only in normal subjects but also in patients with unilateral CVD. This simple method seems to be valuable for the identification of altered neuronal activity in patients with CVD.
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Eur. J. Nucl. Med. Mol. Imaging · Jun 2004
Performance evaluation of the new whole-body PET/CT scanner: Discovery ST.
Characterisation of the physical performance of the new integrated PET/CT system Discovery ST (GE Medical Systems) has been performed following the NEMA NU 2-1994 (N-94) and the NEMA NU 2-2001 (N-01) standards in both 2D and 3D acquisition configuration. The Discovery ST combines a four or eight multi-slice helical CT scanner with a PET tomograph which consists of 10,080 BGO crystals arranged in 24 rings. The crystal dimensions are 6.3 x 6.3 x 30 mm(3) and they are organised in blocks of 6 x 6 crystals, coupled to a single photomultiplier tube with four anodes. ⋯ Using the NEMA N-94 standard, the main results were: (1) the average (radial and tangential) transverse spatial resolution (FWHM) at 1, 10 and 20 cm off axis was 6.28 mm, 7.09 mm and 7.45 mm in 2D, and 6.68 mm, 7.72 mm and 8.13 mm in 3D; (2) the sensitivity for true events was 8,567 cps/kBq/cc in 2D and 36,649 cps/kBq/cc in 3D; (3) the scatter fraction was 15% in 2D and 30% in 3D; (4) the peak true events rate, the true events rate at 50% of the system dead-time and the true events rate when equal to the random events rate were 750 kcps at 189.81 kBq/cc, 744 kcps at 186.48 kBq/cc and 686 kcps at 150.59 kBq/cc, respectively, in 2D, and 922 kcps at 44.03 kBq/cc, 834 kcps at 53.28 kBq/cc and 921 kcps at 44.03 kBq/cc in 3D; (5) the noise equivalent count (NEC) peak rate was 270 kcps at 34.38 kBq/cc in 3D, with random coincidences estimated by delayed events. Using the NEMA N-01 standards the main results were: (1) the average transverse and axial spatial resolution (FWHM) at 1 cm and 10 cm off axis was 6.28 (4.56) mm and 6.88 (6.11) mm in 2D, and 6.29 (5.68) mm and 6.82 (6.05) mm in 3D; (2) the average sensitivity for the two radial positions (r=0 cm and r=10 cm) was 1.93 cps/kBq in 2D and 9.12 cps/kBq in 3D; (3) the scatter fraction was 19% in 2D and 45% in 3D; (4) the NEC peak rate was 54 kcps at 46.99 kBq/cc in 2D and 45.5 kcps at 10.84 kBq/cc in 3D, when random coincidences were estimated by using k=2 in the NEC formula, while the NEC peak rate was 81 kcps at 64.43 kBq/cc and 66 kcps at 14.86 kBq/cc in 2D and 3D, respectively, when random coincidences were estimated by using k=1 in the NEC formula. The new integrated PET-CT system Discovery ST has good overall performances in both 2D and 3D, with in particular a high sensitivity and a very good 3D NEC response.