Simulations of a Multipinhole SPECT Collimator for Clinical Dopamine Transporter (DAT) Imaging

Könik, Arda; Beenhouwer, Jan De; Mukherjee, Joyeeta Mitra; Kalluri, Kesava S.; Banerjee, Soumyanil; Zeraatkar, Navid; Fromme, Timothy J.; King, Michael A.

doi:10.1109/trpms.2018.2831208

Cited by 15 publications

(9 citation statements)

References 38 publications

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“…Finally, as we mentioned earlier, our proposed system has approximately 2–3.3 times reduction in scan time, up to 1.7 times improved volume sensitivity and reasonable spatial resolution for a brain study when compared to the conventional dual‐head scanner. However, if we compare our proposed scanner with an experimental dedicated multi‐pinhole brain SPECT system, 47,48 the dedicated system has good spatial resolution (~4.8 mm FWHM in the center of the cylindrical volume of interest) and the caudate and putamen in the brain phantom are well differentiated due to the magnification of the pinhole collimator for a small spherical volume having a 21 cm‐diameter. In addition, the investigational multi‐pinhole dedicated brain SPECT (e.g., G‐SPECT) having a high spatial resolution (below 3 mm) and a high sensitivity of 415 cps/MBq takes only 30 s for a total brain perfusion scan with optimized bed position sequences 49,50 .…”

Section: Discussionmentioning

confidence: 99%

“…In addition, the investigational multi‐pinhole dedicated brain SPECT (e.g., G‐SPECT) having a high spatial resolution (below 3 mm) and a high sensitivity of 415 cps/MBq takes only 30 s for a total brain perfusion scan with optimized bed position sequences 49,50 . However, these dedicated brain designs using multi‐pinhole collimators have a significant limitation as for general‐purpose imaging scenarios (e.g., bone SPECT) due to a small cylindrical volume of interest 48 . In contrast, our proposed detector head geometry could be radially extended and still could have shorter scan time by swiveling individual detectors, which will be further investigated to optimize the acquisition mode with a slightly common axis of rotation if needed.…”

Section: Discussionmentioning

confidence: 99%

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Evaluation of a variable‐aperture full‐ring SPECT system using large‐area pixelated CZT modules: A simulation study for brain SPECT applications

et al. 2021

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Single photon emission computed tomography (SPECT) scanners using cadmium zinc telluride (CZT) offer compact, lightweight, and improved imaging capability over conventional NaI (Tl)-based SPECT scanners. The main purpose in this study is to propose a full-ring SPECT system design with eight large-area CZT detectors that can be used for a broad spectrum of SPECT radiopharmaceuticals and demonstrate the performance of our system in comparison to the reference conventional NaI(Tl)-based two-head Anger cameras. Methods: A newly designed full-ring SPECT system is composed of eight large-area CZT cameras (128 mm × 179.2 mm effective area) that can be independently swiveled around their own axes of rotation independently and can have radial motion for varying aperture sizes that can be adapted to different sizes of imaging volume. Extended projection data were generated by conjoining projections of two adjacent detectors to overcome the limited field-of-view (FOV) by each CZT camera. Using Monte Carlo simulations, we evaluated this new system design with digital phantoms including a Derenzo hot rod phantom and a Zubal brain phantom. Comparison of performance metrics such as spatial resolution, sensitivity, contrast-to-noise ratio (CNR), and contrast-recovery ratio was made between our design and conventional SPECT scanners having different pixel sizes and radii of rotation (one clinically well-known type and two arbitrary types matched to our proposed CZT-SPECT geometries). Results: The proposed scanner could result in up to about three times faster in acquisition time over conventional scan time at same acquisition time per step. The spatial resolution improvement, or deterioration, of our proposed scanner compared to the clinical-type scanner was dependent upon the location of the point source. However, there were overall performance improvements over the three different setups of the conventional scanner particularly in volume sensitivity (approximately up to 1.7 times). Overall, we successfully reconstructed the phantom image for both 99m Tc-based perfusion and 123 I-based dopamine transporter (DaT) brain studies simulated for our new design. In particular, the striatal/background contrast-recovery ratio in 3-to-1 reference ratio was over 0.8 for the 123 I-based DaT study. Conclusions: We proposed a variable-aperture full-ring SPECT system using combined pixelated CZT and energy-optimized parallel-hole collimator modules and evaluated the performance of this scanner using relevant digital phantoms and MC simulations. Our studies demonstrated the potential of our new full-ring CZT-SPECT design, showing reduced acquisition time and improved sensitivity with acceptable CNR and spatial resolution.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Evaluation of a variable‐aperture full‐ring SPECT system using large‐area pixelated CZT modules: A simulation study for brain SPECT applications

et al. 2021

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“…Cone-beam and fanbeam collimators were used to make better usage of the detector area than parallel-hole collimators when imaging a structure such as the head which is of smaller area than the detector, thereby improving the sensitivity / spatial resolution trade-off for imaging [20,21]. More recently, studies have shown that customized multi-pinhole collimators may further enhance the performance of the existing clinical generalpurpose SPECT systems for brain imaging [22][23][24][25][26].…”

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confidence: 99%

Investigation of Axial and Angular Sampling in Multi-Detector Pinhole-SPECT Brain Imaging

Zeraatkar

Kalluri

Auer

et al. 2020

IEEE Trans. Med. Imaging

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We designed a dedicated multi-detector multipinhole brain SPECT scanner to generate images of higher quality compared to general-purpose systems. The system, AdaptiSPECT-C, is intended to adapt its sensitivity-resolution trade-off by varying its aperture configurations allowing both high-sensitivity dynamic and high-spatial-resolution static imaging. The current system design consists of 23 detector heads arranged in a truncated spherical geometry. In this work, we investigated the axial and angular sampling capability of the current stationary system design. Two data acquisition schemes using limited rotation of the gantry and two others using axial translation of the imaging bed were also evaluated concerning their impact on image quality through improved sampling. Increasing both angular and axial sampling in the current prototype system resulted in quantitative improvements in image quality metrics and qualitative appearance of the images as determined in studies with specifically selected phantoms. Visual improvements for the brain phantoms with clinical distributions were less pronounced but presented quantitative improvements in the fidelity (normalized root-mean-square error (NRMSE)) and striatal specific binding ratio (SBR) for a dopamine transporter (DAT) distribution, and in NRMSE and activity recovery for a brain perfusion distribution. More pronounced improvements with increased sampling were seen in contrast recovery coefficient, bias, and coefficient of variation for a lesion in the brain perfusion distribution. The negligible impact of the most cranial ring of detectors on axial sampling, but its significant impact on sensitivity and angular sampling in the cranial portion of the imaging volume-of-interest were also determined. Index Terms-AdaptiSPECT-C, angular and axial sampling, SPECT, pinhole, multi-pinhole. I. INTRODUCTION B RAIN SPECT imaging has been of interest for many clinical applications in neuroimaging including Alzheimer's, Parkinson's, and Huntington's diseases,

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“…King and co-workers proposed a combination of a MPH collimator on one head of a double-head SPECT system and a fan-beam collimator on the other head (King et al, 2016). The rationale was that the MPH collimator would provide high resolution of 4.8 mm (Konik et al, 2018) and high sensitivity for imaging of the interior portion of the brain, particularly the striatum. The fan-beam collimator would provide lower resolution, but complete sampling of the brain addressing data sufficiency and allowing a volume-of-interest to be defined over cortical brain reference regions for semi-quantitative analysis (King et al, 2016).…”

Section: Accepted Manuscript Discussionmentioning

confidence: 99%

Performance evaluation of a novel multi-pinhole collimator for dopamine transporter SPECT

et al. 2020

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Purpose: There is a tradeoff between spatial resolution and count sensitivity in SPECT with conventional collimators. Multi-pinhole (MPH) collimator technology has potential for concurrent improvement of resolution and sensitivity in clinical SPECT of 'small' organs. This study evaluated a novel MPH collimator specifically designed for dopamine transporter (DAT) SPECT with a triple-head SPECT camera. Methods: Count sensitivity was measured with a 99m Tc point source placed on the lattice points of a 1cm grid covering the whole field-of-view (FOV). Spatial resolution was assessed with a Derenzo type hot rod phantom. An anthropomorphic striatum phantom was scanned with total activity representative of a typical patient scan and different striatum-to-background activity concentration ratios. Recovery of striatum-tobackground contrast was assessed by the contrast-recovery-coefficient. Measurements were repeated with double-head SPECT with fan-beam or low-energy-high-resolution-high-sensitivity (LEHRHS) collimators. A patient referred to DAT SPECT because of suspicion of Parkinson's disease was scanned with both LEHRHS and MPH collimators after a single tracer injection. Results: The axial MPH sensitivity profile was almost symmetrical around its peak, although it was shifted 7cm towards the patient to simplify positioning. Peak sensitivity of the triple-head MPH system in the center of the FOV was 620 cps/MBq compared to 225 cps/MBq for the double-head fan-beam system. Sensitivity of the MPH system decreased towards the edges of the FOV. The full width of the sensitivity profile at 200 cps/MBq was 21cm transaxially and 11cm axially. In MPH SPECT of the Derenzo phantom all rods with ≥ 5mm diameter were clearly visible. MPH SPECT improved striatal contrast recovery by ≥ 20% compared to fan-beam SPECT. The patient scan demonstrated good image quality of MPH SPECT with almost PET-like delineation of putamen and caudate nucleus. Conclusions: SPECT with dedicated MPH collimators provides considerable improvement of the resolution-sensitivity tradeoff in DAT SPECT compared to SPECT with fan-beam or LEHRHS collimators.

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Simulations of a Multipinhole SPECT Collimator for Clinical Dopamine Transporter (DAT) Imaging

Cited by 15 publications

References 38 publications

Evaluation of a variable‐aperture full‐ring SPECT system using large‐area pixelated CZT modules: A simulation study for brain SPECT applications

Evaluation of a variable‐aperture full‐ring SPECT system using large‐area pixelated CZT modules: A simulation study for brain SPECT applications

Investigation of Axial and Angular Sampling in Multi-Detector Pinhole-SPECT Brain Imaging

Performance evaluation of a novel multi-pinhole collimator for dopamine transporter SPECT

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