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

Abstract

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,

Self-Collimating SPECT With Multi-Layer Interspaced Mosaic Detectors

“…The approach to use translational movements of the phantom to improve spatial sampling has been applied in other conventional SPECT systems [40,46]. In this super high resolution self-collimating SPECT, the translational movements play an important role.…”

Impacts of acquisition and reconstruction parameters on the absolute technetium quantification of the cadmium–zinc–telluride-based SPECT/CT system: a phantom study

“…To assess the image quality, we calculated both the per cent contrast and coefficient of variation (COV) complying with the NEMA NU 2-2012 standard [53][54][55][56]. The per cent contrast Q H,j for each hot sphere was calculated by using Eq.…”

Design Study of an Ultrahigh Resolution Brain SPECT System Using a Synthetic Compound-Eye Camera Design With Micro-Slit and Micro-Ring Apertures

“…As the demand for brain SPECT instrumentation with higher spatial resolution, energy resolution and sensitivity continue to rise for studies of neurodegenerative diseases and brain functions, the latest research and commercial systems are based on stationary multi-detector geometries coupled with stationary high-resolution collimators. The G-SPECT-I system [ 2 ], [ 3 ] uses nine large FOV NaI crystals coupled with 54 focusing pinholes, providing an excellent 2.5 mm spatial resolution with a sensitivity of 415 cps/MBq (0.0415%) when 3 mm-diameter pinhole collimators are used, but in a limited FOV of 10 cm D × 6 cm L. A collaboration between the University of Massachusetts and University of Arizona is developing the AdaptiSPECT-C system [ 4 ], [ 5 ], a stationary helmet-shaped brain-dedicated SPECT system. The system presents 23 hexagonal detector heads based on NaI(Tl) scintillators and a multi-aperture collimator with temporal shuttering mechanism [ 6 ], according to the concept of “Adaptive SPECT” introduced by Barrett et al .…”

“…[ 15 ] at University of Arizona introduced the concept of hemispherical system design, where modular cameras were packed in a hemispherical pattern surrounding the patient’s head and coupled with a multiple-pinhole coded aperture. Similarly, the under-development AdaptiSPECT-C system shows a truncated spherical geometry [ 5 ], suited for three-dimensional brain imaging. Extensive work has been done to quantify the improved performance of such geometry [ 4 ], [ 5 ], [ 16 ].…”

“…Similarly, the under-development AdaptiSPECT-C system shows a truncated spherical geometry [ 5 ], suited for three-dimensional brain imaging. Extensive work has been done to quantify the improved performance of such geometry [ 4 ], [ 5 ], [ 16 ].…”