Appropriate collimators in a small animal SPECT scanner with CZT detector

Higaki, Yusuke; Kobayashi, Masato; Uehara, Tomoya; Hanaoka, Hirofumi; Arano, Yasushi; Kawai, Keiichi

doi:10.1007/s12149-012-0681-5

Cited by 13 publications

(5 citation statements)

References 17 publications

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“…High spatial resolution can improve the diagnostic value of SPECT scans if sufficient image quality is achieved, which is particularly affected by the choice of collimator 12 , reconstruction algorithm 5 , 13 , post-reconstruction filter 13 and injection dose 14 . Hence, we evaluated the influence of acquisition time and Gaussian post-filtering, using a novel iterative reconstruction algorithm with similarity-regulated ordered-subsets expectation maximization (SROSEM), that enables constant reconstruction parameters for a wide range of activity concentrations 15 .…”

Section: Introductionmentioning

confidence: 99%

Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging

Janssen

Hoffmann

Kitasaka

et al. 2020

Sci Rep

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We aimed to investigate the image quality of the U-SPECT5/CT E-Class a micro single-photon emission computed tomography (SPECT) system with two large stationary detectors for visualization of rat hearts and bones using clinically available 99mTc-labelled tracers. Sensitivity, spatial resolution, uniformity and contrast-to-noise ratio (CNR) of the small-animal SPECT scanner were investigated in phantom studies using an ultra-high-resolution rat and mouse multi-pinhole collimator (UHR-RM). Point source, hot-rod, and uniform phantoms with 99mTc-solution were scanned for high-count performance assessment and count levels equal to animal scans, respectively. Reconstruction was performed using the similarity-regulated ordered-subsets expectation maximization (SROSEM) algorithm with Gaussian smoothing. Rats were injected with ~ 100 MBq [99mTc]Tc-MIBI or ~ 150 MBq [99mTc]Tc-HMDP and received multi-frame micro-SPECT imaging after tracer distribution. Animal scans were reconstructed for three different acquisition times and post-processed with different sized Gaussian filters. Following reconstruction, CNR was calculated and image quality evaluated by three independent readers on a five-point scale from 1 = “very poor” to 5 = “very good”. Point source sensitivity was 567 cps/MBq and radioactive rods as small as 1.2 mm were resolved with the UHR-RM collimator. Collimator-dependent uniformity was 55.5%. Phantom CNR improved with increasing rod size, filter size and activity concentration. Left ventricle and bone structures were successfully visualized in rat experiments. Image quality was strongly affected by the extent of post-filtering, whereas scan time did not have substantial influence on visual assessment. Good image quality was achieved for resolution range greater than 1.8 mm in bone and 2.8 mm in heart. The recently introduced small animal SPECT system with two stationary detectors and UHR-RM collimator is capable to provide excellent image quality in heart and bone scans in a rat using standardized reconstruction parameters and appropriate post-filtering. However, there are still challenges in achieving maximum system resolution in the sub-millimeter range with in vivo settings under limited injection dose and acquisition time.

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Section: Introductionmentioning

confidence: 99%

Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging

Janssen

Hoffmann

Kitasaka

et al. 2020

Sci Rep

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“…(a: acceptance angle, d: physical pin-hole aperture opening diameter, f: focal distance, z: distance from object to the pin-hole aperture, and θ: incidence angle) [14] provides a better spatial resolution [7,42]. Multi pin-hole collimators have focused peripheral apertures to the FOV [43,44]. SPECT imaging with pin-hole includes small organs such as thyroid, parathyroid glands, knee joints, breast, and also small animal's physiological imaging [7,14,[45][46][47].…”

Section: Pin-hole Collimatorsmentioning

confidence: 99%

Review on Recent Developments in Collimators of Single Photon Emission Computed Tomography Imaging

Darkhor

Islamian

2020

fbt

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In Single Photon Emission Computed Tomography (SPECT), collimator selection, optimization, and also geometric calibration have a major impact on the acquired image quality and also on an accurate detectability and diagnosis. The collimator optimization phenomena consider some parameters such as field of view, resolution, sensitivity, resolution at depth, septal thickness and penetration for a specific application task. While the parallel hole collimator is usually used in SPECT and planar imaging but due to the limited solid angle covered by the collimator, the system sensitivity and resolution were highly reduced. Meanwhile, other types of collimators such as pin-hole, multi-pin-hole, slant and slit-slat collimators were introduced with a trade-off between sensitivity and resolution. This article reviews improvements on collimators also by considering the geometry and geometric calibration methods for improving the image quality in single photon emission computed tomography.

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“…Even though such designs offer high spatial resolution compared to parallel-hole collimation, they are rarely used in clinical routine due to their complex imaging characteristics and low sensitivity. However, (multi-)pinhole collimators are regularly applied in small animal imaging [26], where they are able to achieve sub-millimeter spatial resolutions [27].…”

Section: Technical Principlementioning

confidence: 99%

SPECT/CT technology

Ritt

Sanders

Kuwert

2014

Clin Transl Imaging

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The continuous development of SPECT over the past 50 years has led to remarkably improved image quality and increased diagnostic confidence. The most influential developments include the realization of hybrid SPECT/CT devices, as well as the implementation of attenuation correction and iterative reconstruction techniques. These developments have led to a preference for SPECT/CT devices over SPECT-only systems and to the widespread adoption of the former, strengthening the role of SPECT/CT as the workhorse of nuclear medicine imaging. New trends in the ongoing development of SPECT/CT are quite diverse. For example, whole-body SPECT/CT images, consisting of acquisitions from multiple consecutive bed positions in the manner of PET/CT, are increasingly performed. Another recent advance has been the incorporation of additional information obtained from the CT images into the SPECT reconstruction, thereby allowing CT data to be used for more than just attenuation correction and image fusion. Additionally, in recent years, some interesting approaches in detector technology have found their way into commercial products. For example, some SPECT cameras dedicated to specific organs employ semiconductor detectors made of cadmium telluride or cadmium zinc telluride, which have been shown to increase the obtainable image quality by offering a higher sensitivity and energy resolution. Most important, the recent advent of quantitative SPECT/CT which, like PET, can quantify the amount of tracer in terms of Bq/mL or as a standardized uptake value, is a major innovation that will lead to increased diagnostic accuracy and confidence, especially in longitudinal studies and in the monitoring of treatment response. This article describes some of the physical and technical fundamentals of SPECT/CT and reviews established as well as experimental technical developments. It also introduces the aforementioned recent trends in the field of nuclear medicine imaging, such as specialized collimators, SPECT cameras for anatomical imaging (e.g. cerebral/cardiac imaging) and new detector technologies.

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Appropriate collimators in a small animal SPECT scanner with CZT detector

Cited by 13 publications

References 17 publications

Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging

Capabilities of multi-pinhole SPECT with two stationary detectors for in vivo rat imaging

Review on Recent Developments in Collimators of Single Photon Emission Computed Tomography Imaging

SPECT/CT technology

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