Yap-(s)pet small animal scanner: quantitative results (original) (raw)
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Evaluation of the performance of the YAP-(S) PET scanner and its application in neuroscience
Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 2007
This paper presents the performance evaluation of the small animal scanner YAP-(S)PET, both in PET and SPECT modalities following preliminary NEMA standards for small animal PET. Data are taken with a new version of the scanner that is installed at the IFC-CNR in Pisa (Italy) within the framework of the Center of Excellence AmbiSEN of the University of Pisa. This paper also reports some preliminary SPECT applications in neuroscience using 123 I-FP-CIT (DaTSCAN).
Activity Quantification of Yttrium-90: PET as compared to Bremsstrahlung SPECT
2012
Introduction: Cancer treatment is a process with continuous development. The most common treatment, within the field of radiation physics, is external radiation therapy, whereas one of the least common methods is Selective Internal RadioTherapy (SIRT). SIRT is a rather novel method for treating liver carcinoma. Microspheres containing 90 Y are infused directly into the liver, via the hepatic artery. Seventeen SIRT-treatments have been performed at Skåne University Hospital (SUS) in Lund since the start in December 2010 until today (June 2012). Due to the work of David Minarik, the activity distribution is today quantified post-treatment in clinical routine with the single photon emission computed tomography camera (SPECT) system. However, recent work performed by Lhommel et. al has shown the ability to use the positron emission tomography (PET) system to create PET-images with 90 Y labeled SIR-spheres. Due to the better spatial resolution in the PET-camera, compared to the SPECT-camera, it is of interest to investigate the possibility to use PET instead of SPECT, for activity quantification of SIRT-patients´ liver. A system with a better spatial resolution has the potential to create a more accurate absorbed dose map from the activity distribution within the liver, compared to the SPECT based system used today. The aim of this thesis is to evaluate whether PET can be used for activity quantification after 90 Y microsphere treatments. Once the most suitable camera is chosen, absorbed dose calculation can be performed with the outcome from the activity distribution shown on the PET-or SPECT-images of the liver. Materials and methods: For this project, three patients have been treated with SIRT and imaged in both the PET-and SPECT-camera. Furthermore, phantom measurements have been performed both with 18 F and 90 Y. Results: For all three patients the PET system overestimates the total activity in the liver with about 20%. The SPECT systems result vary between 0% to-15% compared to the true activity within the liver. However, more corrections are required on the PET-images to be certain that extra counts originating from the crystals within the PET cameras detector, does not contaminate the image with background noise, and thus giving an overestimation in activity quantification of about 20%. Conclusion: The results indicate that it is possible to use PET to determine the activity distribution within the liver for patients treated with SIRT. However, further investigations are needed to determine whether PET should replace SPECT.
Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2006
The new and fully engineered version of the YAP-(S)PET small animal scanner has been tested at the University of Mainz for preliminary assessment of its imaging capability for studies related to neuropharmacology and psychiatry. The main feature of the scanner is the capability to combine PET and SPECT techniques. It allows the development of new and interesting protocols for the investigation of many biological phenomena, more effectively than with PET or SPECT modalities alone. The scanner is made up of four detector heads, each one composed of a 4  4 cm 2 of YAlO 3 :Ce (or YAP:Ce) matrix, and has a field of view (FOV) of 4 cm axially  4 cm + transaxially. In PET mode, the volume resolution is less than 8 mm 3 and is nearly constant over the whole FOV, while the sensitivity is about 2%. The SPECT performance is not so good, due to the presence of the multi-hole lead collimator in front of each head. Nevertheless, the YAP-PET scanner offers excellent resolution and sensitivity for performing on the availability of D2-like dopamine receptors on mice and rats in both PET and SPECT modalities. r
Simultaneous PET/SPECT imaging with the small animal scanner YAP-(S)PET
2007 IEEE Nuclear Science Symposium Conference Record, 2007
To exploit the YAP-(S)PET II scanner intrinsic capability of both PET and SPECT imaging, we have implemented the simultaneous PET/SPECT dual imaging modality. Two opposing heads, equipped with collimator and set in anticoincidence, independently acquire single events (SPECT mode), the other pair of heads detects coincidence events (PET mode). During the simultaneous PET/SPECT acquisition, both a high energy (PET) and a low energy (SPECT) radiotracer are placed inside the Field of View (FOV). Since the thickness of the collimator (2 cm) is optimized to stop only low energy photons, the down-scatter from 511 keV photons seriously affects the single photon acquisition. It is therefore necessary to perform a subtraction procedure before SPECT data analysis. The subtraction procedure is based on a multi-energy window method. The background underneath the 99m Tc photo-peak region can then be approximated as a fraction (f) of the counts measured in an energy window close to the photo-peak but containing only Compton events.
Impact of the Arterial Input Function Recording Method on Kinetic Parameters in Small-Animal PET
Journal of Nuclear Medicine, 2018
The goal of this study was to validate the use of an MR-compatible blood sampler (BS) with a detector system based on a lutetium oxyorthosilicate scintillator and avalanche photodiodes for smallanimal PET. Methods: Five rats underwent a 60-min 18 F-FDG study. For each animal, the arterial input function (AIF) was derived from the BS recording, from manual sampling (MS), and from the PET image. These AIFs were applied for kinetic modeling of the striatum using the irreversible 2-tissue-compartment model. The MS-based technique with a dispersion correction served as a reference approach, and the kinetic parameters that were estimated with the BS-and the image-derived AIFs were compared with the reference values. Additionally, the effect of applying a population-based activity ratio for plasma to whole blood (p/wb) and the dispersion correction was assessed. Results: The K 1 , k 2 , and k 3 values estimated with the reference approach were 0.174 ± 0.037 mL/min/cm 3 , 0.342 ± 0.080 1/min, and 0.048 ± 0.009 1/min, respectively. The corresponding parameters obtained with the BS-and image-derived AIFs deviated from these values by 0.6%-18.8% and 16.7%-47.9%, respectively. To compensate for the error in the BS-based technique, data from one MS collected at the end of the experiment were combined with the data from the first 10 min of the BS recording. This approach reduced the deviation in the kinetic parameters to 1.8%-6.3%. Using p/wb led to a 1.7%-8.3% difference from the reference parameters. The sensitivity of the BS was 23%, the energy resolution for the 511-keV photopeak was 19%, and the timing resolution was 11.2 ns. Conclusion: Online recording of the blood activity level with the BS allows precise measurement of AIF, without loss of blood volume. Combining the BS data with one MS is the most accurate approach for the data analysis. The high sensitivity of the device may allow application of lower radioactivity doses.
Radiation Protection Dosimetry, 2010
Positron emission tomography combined with computed tomography (PET/CT) is a quantitative technique suitable for diagnostics and uptake measurements. The quantitative results can be used for the purpose of the calculating absorbed dose to patients undergoing nuclear medicine investigations. Hence, the accuracy of the quantification of the activity content in organs or tissues is of great importance. When using a planar gamma camera and single photon emission computed tomography (SPECT) images, the activity content in organs and tumours has to be determined by the user, using the number of counts in the organs and the efficiency of the camera. However, when using a Philips Gemini TF PET/CT system, the activity concentration in a region of interest (ROI) is given by the system. The reliability of activity concentration values given by the Philips Gemini TF PET/CT system was studied using a Jaszczak phantom containing hot spheres of different sizes; the influence of the ROI size and the impact of organ size, that is the partial volume effect, was investigated with three different lesion-to-background ratios in the phantom. The use of a small ROI size (40 % of the large ROI size, which covered the entire sphere) showed a 15 % improvement in the recovery of the true activity. Small lesion sizes result in large underestimations of the activity concentration values.
Variation in Maximum Counting Rates During Myocardial Blood Flow Quantification Using (82)Rb PET
Journal of nuclear medicine : official publication, Society of Nuclear Medicine, 2017
With great interest, we read the recent article by Renaud et al. entitled "Characterization of 3-Dimensional PET Systems for Accurate Quantification of Myocardial Blood Flow" (1). The authors describe a method to obtain the maximum injected activity for which accurate quantification of myocardial blood flow (MBF) can be achieved. We think that this method majorly contributes to the existing knowledge. It shows that accurate dynamic PET imaging is possible for a range of 3-dimensional PET systems if maximum injected activities are respected to limit peak dead-time losses during the bolus first-pass transit. The authors translated the maximum activities for accurate MBF as determined by phantom studies to maximum patientspecific tracer activities (in MBq/kg). However, in our opinion, this translation might be an oversimplified approach, because the activity distribution and photon attenuation in patients during the first-pass transit do not solely depend on body weight. We think that application of the presented method may lead to higher counting rates in some patients than the maximum counting rates as derived from the phantom study. These higher counting rates may subsequently hamper accurate MBF quantification. To ground our viewpoint, we obtained the maximum prompt coincidence counting rate on our PET system (Ingenuity TF; Philips Healthcare) using the same phantom as described by Renaud et al. (1). Next, we retrospectively obtained the maximum accepted counting rates during myocardial perfusion imaging at rest with 82 Rb PET for 72 consecutive patients. All patients provided written informed consent for the use of their data for research purposes. An activity of 740 MBq was injected at a flow of 50 mL/min (CardioGen-82; Bracco Diagnostics Inc.) in the phantom and in patients. Next, we studied the effect of using the recommended injected activity per body weight as proposed by Renaud et al. (1). Therefore, we multiplied the measured maximum counting rate, normalized to the injected activity, with body weight and 4.6 MBq/kg for each patient. This way, we obtained a simulated maximum counting rate when using 4.6 MBq/kg. We chose 4.6 MBq/ kg because this is the maximum activity per body weight ensuring accurate quantification for a comparable PET system (Gemini; Philips Healthcare) (1). The body weight equivalent of the phantom was set at 50 kg (1). The maximum simulated counting rate for the phantom was 2,001 kcps. The mean body weight of the included patients was 86 6 17 kg, and the body mass index was 28.6 6 5.4 kg/m 2. We found a mean simulated
Performance Evaluation of PETbox: A Low Cost Bench Top Preclinical PET Scanner
Molecular Imaging and Biology, 2000
Purpose PETbox is a low cost bench top preclinical PET scanner dedicated to pharmacokinetic and pharmacodynamic mouse studies. A prototype system was developed at our institute, and this manuscript characterizes the performance of the prototype system. Procedures The PETbox detector consists of a 20 × 44 bismuth germanate crystal array with a thickness of 5 mm and cross-section size of 2.05 × 2.05 mm. Two such detectors are placed facing each other at a spacing of 5 cm, forming a dual-head geometry optimized for imaging mice. The detectors are kept stationary during the scan, making PETbox a limited angle tomography system. 3D images are reconstructed using a maximum likelihood and expectation maximization (ML–EM) method. The performance of the prototype system was characterized based on a modified set of the NEMA NU 4-2008 standards. Results In-plane image spatial resolution was measured to be an average of 1.53 mm full width at half maximum for coronal images and 2.65 mm for the anterior–posterior direction. The volumetric reconstructed resolution was below 8 mm3 at most locations in the field of view (FOV). The sensitivity, scatter fraction, and noise equivalent count rate (NECR) were measured for different energy windows. With an energy window of 150 - 650 keV and a timing window of 20 ns optimized for mouse imaging, the peak absolute sensitivity was 3.99% at the center of FOV and a peak NECR of 20 kcps was achieved for a total activity of 3.2 MBq (86.8 μCi). Phantom and in vivo imaging studies were performed and demonstrated the utility of the system at low activity levels. The quantitation capabilities of the system were also characterized showing that despite the limited angle tomography, reasonably good quantification accuracy was achieved over a large dynamic range of activity levels. Conclusions The presented results demonstrate the potential of this new tomograph for small animal imaging.
IEEE Transactions on Nuclear Science, 2003
A small animal PET-SPECT scanner (YAP-(S)PET) prototype was built at the Physics Department of the University of Ferrara and is presently being used at the Nuclear Medicine Department for radiopharmaceutical studies on rats. The first YAP-(S)PET prototype shows very good performances, but needs some improvements before it can be used for intensive radiopharmaceutical research. The main problem of the actual prototype is its heavy electronics, based on NIM and CAMAC standard modules. For this reason a new, compact readout electronics was developed and tested. The results of a first series of tests made on the first prototype will be presented in this paper.
Performance evaluation of the fully engineered YAP-(S)PET scanner for small animal imaging
IEEE Transactions on Nuclear Science, 2000
a new and fully engineered version of the YAP-(S)PET small animal scanner has been recently installed. The new YAP-(S)PET is able to perform both PET and SPECT studies on small animals. The scanner is made up of four heads: each one is composed of a 4 4 cm 2 YAlO 3 :Ce (or YAP:Ce) matrix of 20 20 elements, 2 2 25 mm 3 each, coupled to a Position Sensitive Photomultiplier (PS-PMT) (Hamamatsu R2486). The four modules are positioned on a rotating gantry. The switching to the SPECT modality is easily made by mounting a high resolution parallel hole (0.6 mm , 0.15 mm septum) lead collimator in front of each crystal. This paper reports the performance of the system in terms of absolute sensitivity and spatial resolution for both PET and SPECT modalities. The scatter fraction and noise-equivalent count rate (NEC) for a mouse phantom for different energy windows have been measured in PET modality. Images of phantoms and animals are also presented. Index Terms-Molecular imaging, positron emission tomography (PET), single photon emission tomography, small animal imaging. Authorized licensed use limited to: UNIVERSITA PISA S ANNA. Downloaded on November 21, 2008 at 03:44 from IEEE Xplore. Restrictions apply.