Click on a content entry to get a more detailed information.
Quantitative methods for clinical SPECT epilepsy and Parkinson's imaging (#4354)
1 Yale University, New Haven, Connecticut, United States of America
Clinical brain SPECT imaging has played a significant role in the evaluation of several patient disorders. Early investigations of brain perfusion helped to better understanding stroke, dementia, and even preliminary investigations of mental disorders. An especially successful clinical brain SPECT application relies on ictal and inter-ictal SPECT scans as an aid for localizing areas of seizure onset in epilepsy. More recent radiotracer development has led to an array of neuro-receptor agent, and notably plays a vital role in Parkinson's diagnosis. SPECT brain imaging continues to be important for clinical trial studies and holds the promise for a resurgence in clinical applications hinging on improved camera designs.
Keywords: Clinical brain SPECT, SPECT, Brain
NIRS brain PET prototypes with the 4-layer DOI detector technology (#4335)
T. Yamaya1, E. Yoshida1, F. Nishikido1, H. Tashima1, A. Mohammadi1, Y. Iwao1, M. S. H. Akram1, M. Nitta1, T. Obata1
1 National Institute of Radiological Sciences (NIRS- QST), Chiba, Japan
PET plays important roles in cancer diagnosis, neuroimaging and molecular imaging research; but potential points remain for which big improvements could be made, including spatial resolution, sensitivity and manufacturing costs. Higher spatial resolution is essential for enable earlier diagnosis, and improved sensitivity results in reduced radiation exposure and shortened measurement time. For example, the sensitivity of present PET scanners does not exceed 5%. This means that more than 95% of the gamma-rays emitted from a subject are not utilized for imaging. Therefore, research on next generation PET technologies remains a hot topic worldwide. Depth-of-interaction (DOI) measurement in the radiation sensor will be a key technology to get any significant improvement in sensitivity while maintaining high spatial resolution. Therefore we have developed 4-layered DOI-type detectors based on our original light-sharing method. DOI measurement has a potential to expand PET application fields because it allows for more flexible detector arrangement. Good examples are our two developments: the helmet-chin PET prototype and the add-on PET prototype. In the helmet-chin PET prototype, we showed that the average sensitivity of a hemisphere detector arrangement is about 1.5-times higher than that of a cylinder detector arrangement in case the total number of detectors is the same. In addition, innovation of silicon photomultipliers (SiPMs) encouraged us development of PET/MRI, which is attracting great notice in terms of smaller radiation exposure and better contract in soft tissues compared with current PET/CT. By using our SiPM-based DOI detectors, we developed the “add-on” PET, which is a novel, high-performance and low-cost brain PET/MRI to meet demands for earlier diagnosis of Alzheimer’s disease. The key concept is a RF coil with DOI-PET detectors, which has a potential to upgrade any existing MRI to PET/MRI.
Keywords: depth-of-interaction, DOI, PET, MRI
Mini-EXPLORER II - a prototype high-sensitivity PET/CT scanner for human brain and companion animal scanning (#4347)
Y. Lv1, X. Lv1, W. Liu1, M. S. Judenhofer2, S. R. Cherry2, R. D. Badawi2
1 Shanghai United Imaging Healthcare, Co., Ltd., Shanghai, China
As part of the EXPLORER total-body PET project, we have designed and built a high-resolution, high-sensitivity PET/CT scanner which is expected to have high performance for human brain imaging, as well as for animal imaging. The device has a ring diameter of 52 cm and an axial field of view of 48.3 cm. The detector modules are composed of arrays of LYSO crystals of dimensions 2.76x2.76x18.1 mm. Read-out is performed using SensL J-series SiPMs. We have assessed performance for a variety of parameters. System time-of-flight resolution was measured to be ~409 ps and average system energy resolution was ~11.7% at 511 keV. The NEMA NU2 2012 system sensitivity was found to be 55 kcps/MBq. Spatial resolution was found to be 2.6 mm at 10 mm from the center of the FOV. 2.0 mm rods were clearly resolved on a mini-Derenzo phantom. Peak NEC, using the NEMA NU-2 2012 phantom, was measured to be 298.7 kcps at 8.4kBq/cc. We have performed scans of a Hoffman brain phantom and initial in vivo tests using a rabbit have been completed. We aim to perform the first human studies shortly.
Keywords: EXPLORER, brain, companion animal, total-body PET, PET/CT
A Portable Convertible PET Scanner for Brain Imaging (#4320)
Y. Wu1, J. J. Puz1, N. Tomaszewski1, Z. Zhou1, Y. Gao1, L. Ma1, X. Dong1, N. Newsom1, P. B. Thomas1, F. Daghighian1
1 Prescient Imaging LLC, Hawthorne, California, United States of America
A portable and convertible Positron Emission Tomography (PET) scanner has been developed for imaging the brain, breast and extremities. The PET scanner is on the wheels and the total weight is less than 450 lbs. This makes the scanner transportable between rooms by two persons and between buildings through a minivan. The scanner head can be adjusted by the user to different positions for a variety of applications. The scanner head has an opening of 27.5 cm and trans-axial field of view (FOV) of 25 cm and axial FOV of 10 cm. A double-stacked, staggered array of lutetium fine silicate (LFS) was coupled to an 8x8 array of 3x3 mm MPPCs (Hamamatsu Photonics K.K., Japan) to provide depth-of-interaction. The pixel of the LFS was 1.76x1.76 mm and placed on a pitch of 1.83mm and the lengths are 8 mm (top) and 12 mm (bottom). The MPPC output is then amplified by the ASIC and conditioned by analog electronics, finally digitalized by the ADC. The digital singles data are transferred to a coincidence processing board to sort out the prompts and random coincidence events. The data are processed with GPUs and the image is reconstructed with an iterative algorithm. To evaluate the performance, phantoms were scanned according to the NEMA standard. The preliminary results show good performance. The average spatial resolution is 3.5 mm with FBP reconstruction, the absolute sensitivity at the center of field of view is 5.7%.
Keywords: Portable, Brain, PET
Mind-Tracker PET: A wearable PET camera for brain imaging (#4324)
J. Xu1, Z. Zhao2, S. Xie1, D. Shi1, Q. Huang2, Q. Peng3
1 Huazhong University of Science and Technology, Wuhan, China
PET is a powerful tool in both the neurologic studies and brain-related clinic applications. However, the conventional method of imaging subject in supine is not always desirable for brain imaging.
In this study, we have designed and fabricated a wearable PET camera named Mind-Tracker PET for brain imaging. The aperture and the AFOV of the system are 200 mm and 32 mm, respectively. The Mind-Tracker PET consists of 16 detector modules, 16 readout electronics boards (named Pico-PET electronics), and a 3D printed gantry. The detector module consists of a 10 x 10 LYSO crystal array (single crystal size: 3 mm x 3 mm x 20 mm, array size: 32 mm x 32 mm x 20 mm), and a 10 x 10 SiPM array (SensL, J-series SiPM, 3 mm, array size: 32 mm x 32 mm). The discrete crystals and the SiPMs are one-to-one coupled. All 16 crystal arrays and SiPM arrays are characterized by the Pico-PET electronics. The results show excellent performances in term of gain, dark current, break-down voltage and energy resolution.
The total weight of the scanner is 3,325 grams, which is lighter than the commonly-used motorcycle helmet. The weight of the battery and the host PC are about 2,000 grams. They are assembled and put in a backpack. A healthy grownup can wear the system for brain imaging for hours. This Mind-Tracker PET system makes it possible to monitor the neurologic activities in the brain when the subject in more natural states, such as sitting and walking. We are currently calibrating the Mind-Tracker PET system and preparing for the phantom study.
Keywords: wearable PET, Brain imaging
Phantom test procedures and criteria for standardization of brain PET imaging across different cameras (#4325)
G. Akamatsu1, 5, Y. Ikari2, 5, H. Wakizaka1, 5, T. Yamaya1, 5, Y. Kimura3, 5, K. Oda4, 5, M. Senda2, 5
1 National Institutes for Quantum and Radiological Sciences and Technology, National Institute of Radiological Sciences, Chiba, Japan
Brain PET imaging technique is valuable for clinical researches as well as for clinical practices. However, image quality and quantitative capability of PET data depend on the PET camera model and the details of acquisition protocol, which makes it a challenge to acquire reliable data in a multicenter clinical study. To make multicenter brain PET data meaningful and to contribute to establishing brain PET as a verified imaging biomarker, we have proposed methods of evaluating absolute quantitative capability, resolution, contrast, uniformity, image noise, etc., using appropriate phantoms for standardization among different camera models. At this moment, we have issued phantom test procedures for brain PET with 11C-methionine, 18F-FDG, and amyloid agents (11C-PiB, 18F-florbetapir, 18F-flutemetamol, and 18F-florbetaben). We first defined the phantom models and the elements of quality that are essential for brain methionine, FDG, and amyloid PET images. Those phantoms that are commercially available and easy to use have been selected: so-called brain tumor phantom for brain methionine PET and Hoffman 3D brain phantom and uniform cylindrical phantom for brain FDG and amyloid PET. Subsequently, we have determined a physical performance indicator and criteria for the phantom tests for each PET drug, which was evaluable and achievable with most of the PET camera models. As a result, these phantom test procedures have been used in a number of multicenter PET studies including Japanese Alzheimer’s Disease Neuroimaging Initiative (J-ADNI). The proposed phantom test and criteria facilitate standardization of brain PET imaging and are useful to validate brain PET scanning performance of the imaging sites.
Keywords: Brain PET, standardization, phantom, amyloid, image analysis
Kinetic and Wavelet Analysis of Dynamic FDG PET Data in Human Glioblastoma (#4345)
Y. Li1, C. Leiva-Salinas1, D. Schiff3, P. Rehm1, S. Majewski1, B. Kundu1, 2
1 University of Virginia, Radiology and Medical Imaging, Charlottesville, Virginia, United States of America
Brain tumor detection and therapeutic evaluation continue to be very challenging. Distinguishing between radiation induced necrosis and recurrent or viable residual tumor in human glioblastoma has proved to be a particularly difficult task. The aim of this work is to extract the time course features of the pharmacokinetics of F18-FDG after intra-venous injection using dynamic Positron Emission Tomography (PET) imaging and utilize the features based on kinetic modeling and wavelet transform (WT) as new methods for brain tumor diagnosis other than MRI and static PET images. These methods provide additional functional information to assist with classification of tumor types, i.e. metastasis, recurrent tumor, versus treatment induced changes, such as radiation necrosis. When combined with the novel dedicated brain PET imagers this dynamic PET technique can provide an even more powerful new diagnostic tool. We are also considering application of other imaging agents in addition to FDG.
Keywords: Dynamic FDG PET, Kinetic modeling, Wavelet Transform, Glioblastoma