Performance test of a LSO-APD PET module in a 9.4 Tesla magnet

Pichler, Bernd J.; Lorenz, E.; Mirzoyan, R.; Pimpl, W.; Röder, Falk; Schwaiger, Markus; Ziegler, Sibylle

doi:10.1109/nssmic.1997.670533

Cited by 61 publications

(57 citation statements)

References 8 publications

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“…Most important, APDs are semiconductor devices and therefore have the potential to become less expensive as the production volume increases. APDs not only are compact but also are insensitive to magnetic fields (41) and therefore ideal as PET light …”

Section: Pet Advances In Pet Detector Technologymentioning

confidence: 99%

Latest Advances in Molecular Imaging Instrumentation

Pichler¹,

Wehrl²,

Judenhofer³

2008

J Nucl Med

194

110

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This review concentrates on the latest advances in molecular imaging technology, including PET, MRI, and optical imaging. In PET, significant improvements in tumor detection and image resolution have been achieved by introducing new scintillation materials, iterative image reconstruction, and correction methods. These advances enabled the first clinical scanners capable of time-of-flight detection and incorporating point-spread-function reconstruction to compensate for depth-of-interaction effects. In the field of MRI, the most important developments in recent years have mainly been MRI systems with higher field strengths and improved radiofrequency coil technology. Hyperpolarized imaging, functional MRI, and MR spectroscopy provide molecular information in vivo. A special focus of this review article is multimodality imaging and, in particular, the emerging field of combined PET/MRI. PETi s a high-performance imaging technology that can image the whole-body distribution of positron-emitting biomarkers with high sensitivity. The invention of PET dates back more than 30 y. However, the acceptance of PET as a routine clinical diagnostic tool has been hampered by the need for an on-site cyclotron and a radiochemistry unit for the production of the short-lived radiotracers (1-7). With the availability of commercial radiopharmacies that supply PET probes and with the relatively broad insurance coverage for a variety of clinical indications, the number of PET centers now totals more than 2,000 worldwide.Major technologic milestones in the development of PET include the discovery of faster and brighter scintillators such as lutetium oxyorthosilicate (LSO), gadolinium oxyorthosilicate, and lutetium yttrium oxyorthosilicate. Furthermore, the continuing development of the detectors, progressing from one-to-one scintillator-to-photomultiplier-tube (PMT) coupling (8,9) to advanced block and Anger readout schemes, helps to limit the costs of a PET scanner by providing a multiplexed readout and reduced electronic channels (10-13).The use of faster scintillators enabled the transition from 2-dimensional data acquisitions for whole-body PET, using lead or tungsten collimators as septa (14-16), to 3-dimensional (3D) acquisitions (17). However, approximately an 8-fold increase in detection sensitivity is accompanied by an increased fraction of random and scattered photon events leading to degradation of image quality if not corrected during image reconstruction (18). This degradation effectively reduces the increase in sensitivity from a factor of 8 to approximately 5-fold. To achieve high-quality and quantitative PET data, various image reconstruction techniques have evolved (19). One simple approach is filtered backprojection, which is computationally fast but results in poor image quality if the count statistics of the available PET data are inadequate. Better image quality and improved spatial resolution are achieved by iterative methods such as ordered-subset expectation maximization or maximumlikelihood expectation maximiza...

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Section: Pet Advances In Pet Detector Technologymentioning

confidence: 99%

Latest Advances in Molecular Imaging Instrumentation

Pichler¹,

Wehrl²,

Judenhofer³

2008

J Nucl Med

194

110

View full text Add to dashboard Cite

show abstract

“…The use of semiconductor photodetectors, such as avalanche photodiodes (APD) offers an alternative to PMTs, which is currently being pursued by several research groups [4]. APDs are compact and insensitive to magnetic fields, compared with PMTs, but currently available APDs have low gains, of the order of few a hundreds, and thus require sophisticated preamplifiers and/ or cooling.…”

Section: Introductionmentioning

confidence: 99%

Performance evaluation of SiPM photodetectors for PET imaging in the presence of magnetic fields

España

Fraile

Herraiz

et al. 2010

Nuclear Instruments and Methods in Physics Research Section A:

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a b s t r a c tThe multi pixel photon counter (MPPC) or silicon photomultiplier (SiPM), recently introduced as a solid state photodetector, consists of an array of Geiger mode photodiodes (microcells). It is a promising device for PET due to its potential for high photon detection efficiency (PDE) and its foreseeable immunity to magnetic fields. It is also easy to use with simple read outs, has a high gain and a small size. In this work we evaluate the in field performance of three 1 Â 1 mm 2 (with 100, 400 and 1600 microcells, respectively) and one 6 Â 6 mm 2 (arranged as a 2 Â 2 array) Hamamatsu MPPCs for their use in PET imaging. We examine the dependence of the energy resolution and the gain of these devices on the temperature and reverse bias voltage, when coupled to LYSO scintillator crystals under conditions that one would find in a PET system. We find that the 400 and 1600 microcells models and the 2 Â 2 array are suitable for small size crystals, like those employed in high resolution small animal scanners. We have confirmed the good performance of these devices up to magnetic fields of 7 T as well as their suitability for performing PET acquisitions in the presence of fast switching gradients and high duty radiofrequency MRI sequences.

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“…The first hybrid PET/MRI detectors were developed by Shao et al (16) in the late 1990s using scintillation crystals placed inside a clinical 1.5-T MRI scanner and coupled to long optical fibers leading to conventional photomultiplier tubes outside the fringe magnetic field. A different approach was taken by Pichler et al-that of using avalanche photodiodes instead of photomultiplier tubes to construct an MRIcompatible PET system (17). Recently, the first hybrid PET/MRI systems with avalanche photodiodes for preclinical and clinical applications have been installed (18,19).…”

mentioning

confidence: 99%

Hybrid PET/MRI of Intracranial Masses: Initial Experiences and Comparison to PET/CT

Boss¹,

Bisdas²,

Kolb³

et al. 2010

J Nucl Med

228

129

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Simultaneous PET and MRI using new hybrid PET/MRI systems promises optimal spatial and temporal coregistration of structural, functional, and molecular image data. In a pilot study of 10 patients with intracranial masses, the feasibility of tumor assessment using a PET/MRI system comprising lutetium oxyorthosilicate scintillators coupled to avalanche photodiodes was evaluated, and quantification accuracy was compared with conventional PET/CT datasets. Methods: All measurements were performed with a hybrid PET/MRI scanner consisting of a conventional 3-T MRI scanner in combination with an inserted MRI-compatible PET system. Attenuation correction of PET/MR images was computed from MRI datasets. Diagnoses at the time of referral were low-grade astrocytoma (n 5 2), suspicion of low-grade astrocytoma (n 5 1), anaplastic astrocytoma (World Health Organization grade III; n 5 1), glioblastoma (n 5 2), atypical neurocytoma (n 5 1), and meningioma (n 5 3). In the glial tumors, 11 C-methionine was used for PET; in the meningiomas, 68 Ga-DOTATOC was administered. Tumor-togray matter and tumor-to-white matter ratios were calculated for gliomas, and tracer uptake of meningiomas was referenced to nasal mucosa. PET/MRI was performed directly after clinically indicated PET/CT examination. Results: In all patients, the PET datasets showed similar diagnostic image quality on the hybrid PET/MRI and the PET/CT studies; however, slight streak artifacts were visible in coronal and sagittal sections when using the higher intrinsic resolution of the PET/MRI insert. Prefiltering of images with a 4-mm gaussian filter at a resolution comparable to that of the PET/CT system virtually eliminated these artifacts. Although acquisition of the PET/MR images started at 30-60 min after PET/CT (20.4-min half-life of 11 C) acquisition, the signal-to-noise ratio was good enough, thus underlining the high sensitivity of the PET insert, compared with whole-body PET systems. The computed tumor-to-reference tissue ratios exhibited an excellent accordance between the PET/MRI and PET/CT systems, with a Pearson correlation coefficient of 0.98. Mean paired relative error was 7.9% 6 12.2%. No significant artifacts or distortions were detected in the simultaneously acquired MR images using the PET/MRI scanner. Conclusion: Structural, functional, and molecular imaging in patients with brain tumors is feasible with diagnostic imaging quality using simultaneous hybrid PET/MR image acquisition.

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Performance test of a LSO-APD PET module in a 9.4 Tesla magnet

Cited by 61 publications

References 8 publications

Latest Advances in Molecular Imaging Instrumentation

Latest Advances in Molecular Imaging Instrumentation

Performance evaluation of SiPM photodetectors for PET imaging in the presence of magnetic fields

Hybrid PET/MRI of Intracranial Masses: Initial Experiences and Comparison to PET/CT

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