Hui Liu

Yale University | YU · internal medicine (cardiology)

As PET imaging is accompanied by radiation exposure and potentially increased cancer risk, reducing radiation dose in PET scans without compromising the image quality is an important topic. Deep learning (DL) techniques have been investigated for low-dose PET imaging. However, existing models have often resulted in compromised image quality when ac...

Purpose We have developed a bone-dedicated collimator with higher sensitivity but slightly degraded resolution on single-photon emission computed tomography (SPECT) for planar bone scintigraphy, compared with conventional low-energy high-resolution collimator. In this work, we investigated the feasibility of using the blind deconvolution algorithm...

Purpose Myocardial perfusion imaging (MPI) using single‐photon emission‐computed tomography (SPECT) is widely applied for the diagnosis of cardiovascular diseases. In clinical practice, the long scanning procedures and acquisition time might induce patient anxiety and discomfort, motion artifacts, and misalignments between SPECT and computed tomogr...

Purpose Deep-learning-based attenuation correction (AC) for SPECT includes both indirect and direct approaches. Indirect approaches generate attenuation maps (μ-maps) from emission images, while direct approaches predict AC images directly from non-attenuation-corrected (NAC) images without μ-maps. For dedicated cardiac SPECT scanners with CZT dete...

Background: The GE Discovery NM (DNM) 530c/570c are dedicated cardiac SPECT scanners with 19 detector modules designed for stationary imaging. This study aims to incorporate additional projection angular sampling to improve reconstruction quality. A deep learning method is also proposed to generate synthetic dense-view image volumes from few-view...

It has been proved feasible to generate attenuation maps (μ-maps) from cardiac SPECT using deep learning. However, this assumed that the training and testing datasets were acquired using the same scanner, tracer, and protocol. We investigated a robust generation of CT-derived μ-maps from cardiac SPECT acquired by different scanners, tracers, and pr...

The image quality in clinical PET scan can be severely degraded due to high noise levels in extremely obese patients. Our work aimed to reduce the noise in clinical PET images of extremely obese subjects to the noise level of lean subject images, to ensure consistent imaging quality. The noise level was measured by normalized standard deviation (NS...

Background Attenuation correction can improve the quantitative accuracy of single-photon emission computed tomography (SPECT) images. Existing SPECT-only systems normally can only provide non-attenuation corrected (NC) images which are susceptible to attenuation artifacts. In this work, we developed a post-reconstruction attenuation correction (PRA...

PurposeDeep convolutional neural networks (CNN) for single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) has been used to improve the diagnostic accuracy of coronary artery disease (CAD). This study was to design and evaluate a deep learning (DL) approach to automatic diagnosis of myocardial perfusion abnormalities...

Purpose Positron emission tomography (PET) imaging with various tracers is increasingly used in Alzheimer's disease (AD) studies. However, access to PET scans using new or less‐available tracers with sophisticated synthesis and short half‐life isotopes may be very limited. Therefore, it is of great significance and interest in AD research to assess...

Purpose The net uptake rate constant (Ki) derived from dynamic imaging is considered the gold standard quantification index for FDG PET. In this study, we investigated the feasibility and assessed the clinical usefulness of generating Ki images for FDG PET using only two 5‐min scans with population‐based input function (PBIF). Methods Using a Siem...

Background Attenuation correction (AC) using CT transmission scanning enables the accurate quantitative analysis of dedicated cardiac SPECT. However, AC is challenging for SPECT-only scanners. We developed a deep learning-based approach to generate synthetic AC images from SPECT images without AC.MethodsCT-free AC was implemented using our customiz...

Previous studies have demonstrated the feasibility of reducing noise with deep learning-based methods for low-dose fluorodeoxyglucose (FDG) positron emission tomography (PET). This work aimed to investigate the feasibility of noise reduction for tracers without sufficient training datasets using a deep transfer learning approach, which can utilize...

PurposeAttenuation correction using CT transmission scanning increases the accuracy of single-photon emission computed tomography (SPECT) and enables quantitative analysis. Current existing SPECT-only systems normally do not support transmission scanning and therefore scans on these systems are susceptible to attenuation artifacts. Moreover, the us...

Background Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) has shown diagnostic and prognostic values for the assessment of coronary artery disease (CAD). This study aimed to evaluate in patients a highly automatic Yale-MQ (myocardial blood flow quantification) software incorporated with a novel image segmentation ap...

Objectives We aimed to develop a dynamic imaging technique for a novel PET superoxide tracer, [18F]DHMT, to allow for absolute quantification of myocardial reactive oxygen species (ROS) production in a large animal model.Methods Six beagle dogs underwent a single baseline dynamic [18F]DHMT PET study, whereas one animal underwent three serial dynami...

Purpose In this work, we proposed a triple‐factor non‐negative matrix factorization (TNMF) method to semiautomatically segment the regions of interest (ROIs) of the left ventricular (LV) cavity and myocardium to improve the reproducibility of myocardial blood flow (MBF) quantification from dynamic ⁸²Rb positron emission tomography (PET). Methods T...

Objectives: Previous studies have demonstrated the feasibility of absolute quantification of dynamic123I-metaiodobenzylguanidine (123I-mIBG) single photon emission computed tomography (SPECT) imaging in human. This work reports on simplified quantification of dynamic123I-mIBG SPECT using practical protocols with shortened acquisition time and voxe...

Purpose: Segmentation of contrast-enhanced CT and measurement of SPECT point spread function (PSF) are usually required for conventional partial volume correction (PVC). This study was to develop a segmentation-free method with blind deconvolution (BD) and anatomical-based filtering for SPECT PVC. Methods: The proposed method was implemented usi...

Purpose: Partial volume correction (PVC) methods typically improve quantification at the expense of increased image noise and reduced reproducibility. In this study, the authors developed a novel voxel-based PVC method that incorporates anatomical knowledge to improve quantification while suppressing noise for cardiac SPECT/CT imaging. Methods: In...

Due to the limited spatial resolution, partial volume effect has been a major degrading factor on quantitative accuracy in emission tomography systems. This study aims to investigate the performance of several anatomical-based partial volume correction (PVC) methods for a dedicated cardiac SPECT/CT system (GE Discovery NM/CT 570c) with focused fiel...

PET, SPECT and CT imaging techniques are widely used in preclinical small animal imaging applications. In this paper, we present a compact small animal PET/SPECT/CT tri-modality system. A dual-functional, shared detector design is implemented which enables PET and SPECT imaging with a same LYSO ring detector. A multi-pinhole collimator is mounted o...

Partial volume correction (PVC) methods typically improve quantification at the expense of increasing image noise. In this study, we developed a novel voxel-based PVC method that incorporates anatomical knowledge to improve quantification while suppressing noise for cardiac SPECT/CT imaging. In the proposed method, the SPECT images were first recon...

High-resolution dedicated cardiac SPECT systems with CZT detectors have a great potential to provide 3D molecular breast imaging of sub-cm tumors. In this study, we investigated the feasibility of breast imaging using a dedicated cardiac SPECT system (GE Discovery 530c/570c) by simulating different lesion sizes, positions, and contrasts. Noise-free...

For multi-pinhole small animal SPECT imaging, system matrix (SM) is critical for accurate reconstruction. It is typically achieved by analytical calculation, experimental measurement, or Monte-Carlo (MC) simulation. MC simulation method is relatively accurate and avoids long-time measurements. However, to achieve high resolution for small animal re...

This work aimed to develop and evaluate the CT imaging performance in Nucmed Inliview 3000 animal PET/SPECT/CT system. Accurate geometrical calibration was implemented to enable the high resolution animal CT imaging. With the three ball bearings with known relative position, the projection data were acquired in helical scanning with 1333 views, 0.6...

The goal of this study was to investigate scatter photon cross-talk in two SPECT/CT imaging systems when performing SPECT and CT scans for the same axial field of view (FOV) simultaneously. The Monte Carlo simulation software, Geant4 Applications for Emission Tomography(GATE), was employed in the investigation. The first system was a clinical SPECT...

The aim of this work is to develop, validate and preliminarily evaluate two graphic processing units (GPU) implementations of the OS-EM iterative image reconstruction algorithms for a clinical SPECT system. The Monte Carlo software SIMSET was used to simulate the data acquisition of a typical SPECT camera with a parallel-hole collimator for the She...

In this study, the feasibility for simultaneous PET and SPECT dual-tracer small animal imaging is investigated. A custom-made PET/SPECT imaging system was modeled in this simulation study. In this system, PET imaging was performed with a stationary LYSO detector ring, and SPECT imaging of Tc-99m was conducted with the same detectors and a ring-shap...

For a multi-pinhole SPECT system, it is important to choose an optimal scanning orbit to fulfill the sampling completeness requirement. In this study, we propose a novel four-degree-of-freedom (4-DOF) orbit which combines a conventional helical scanning path and a superimposed periodic reciprocating 3×3-pioint shift movement in transaxial plane. An...

In this study, we design a stationary multi-pinhole SPECT collimator inserted to a small animal PET scanner and investigate the feasibility of SPECT imaging in this system with Monte Carlo simulation studies. Compared to preceding approaches, the unique aspect of the proposed design is that it enables SPECT imaging only by axial translation of the...

As a good film electrode material for supercapacitor, carboxyl ruthenium oxide has been prepared using precursor of isopropyl alcohol solution of RuCl3·3H2O by in-situ decomposition. The phase structure, micro-morphology and capacitance of the film have been studied by infrared spectrometer, scanning electron microscope (SEM), transmission electron...

An SPECT system dedicated to small animal imaging shall be of a millimeter spatial resolution or even better. This study was aimed at achieving 0.5-mm spatial resolution for a small animal SPECT system at low cost. It was developed from a single-head clinical SPECT scanner, with a seven-pinhole collimator and a four-degree-of-freedom motion control...

To research low-cost, high specific capacitance key composite electrode materials for super-capacitors, ruthenium oxide coated active carbon (RuO 2/AC) was prepared by coating and thermal decomposition of ruthenium chloride on AC matrix. The morphology of the composite electrode was investigated by SEM. The performances of RuO 2/AC composite membra...

As a good film electrode material for supercapacitor (Ru-Sn)O2 · nH2O film was deposited on tantalum foils with aqueous solution of (Ru-Sn)Clx as reservoir by galvanostatic-differential pulse voltammetry and heat treatment. The surface morphology, phase transition of precursor (Ru-Sn)Clx to amorphous (Ru-Sn)O2 · nH2O and capacitance of the film wer...

In this study we investigate a specific animal SPECT imaging system with a clinical SPECT detector and a multipinhole collimator insert. High accuracy geometrical calibration is a crucial technique in terms of achieving the high SPECT imaging resolution. The calibration steps include: 1) The SPECT system is modeled with a geometrical projection equ...

As a good film electrode material for supercapacitor, carboxyl ruthenium oxide was prepared using precursor of isopropyl alcohol solution of RuCl3·3H2O by in-situ decomposition. The micro-morphology, thermal decomposition mechanism and capacitance of the film were studied by means of scanning electron microscopy, X-ray photoelectron spectroscopy, i...

Due to the many factors affecting the quality of the laser welding, though there are a lot of process parameters researches on the laser welding, the effective means of the optimization of the process parameters is deficient. Taguchi approach is used as statistical design of experiment(DOE) technique for optimizing the laser welding parameters in t...

In order to develop animal SPECT imaging technology with low cost, we propose a dedicated multi-pinhole collimator design scheme on a clinical SPECT scanner to achieve high resolution. Based on the proposed design one can also optimize current system design for different application purposes. This work is focused on achieving half-mm SPECT imaging...

In order to develop animal SPECT imaging technology on clinical SPECT scanners, we propose a highly flexible multi-pinhole collimator design scheme. The proposed design allows individual adjustment of important system parameters, so that the collimator device is adaptable to various SPECT systems, and one can also optimize different specific aspect...

Spray-formed Si-Al alloys were one kinds of the novel electronic packaging materials due to their lower thermal expansion coefficients, high heat conductivity and lower density, which made it an extensive prospect for application. Unfortunately, the brazing performance of Si-Al series alloys was found to be very poor due to very high silicon conten...

According to the application demand of novel integrated structural-functional materials for electronic packaging in electronic information industry, high-silicon aluminum alloys (50%-70%Si, mass fraction) were fabricated by a combination method of spray forming and hot compression. The microstructure, thermal-physical and mechanical properties were...

The influence of different aging tempers on mechanical and stress corrosion properties of a novel Al-7.5Zn-1.7Mg-1.4Cu-0.12Zr alloy was studied by the measurement of mechanical properties and electrical conductivity, slow strain rate testing (SSRT), and the TEM analysis of microstructure. The results showed that the mechanical properties and stress...

The welding experiment was conducted for spray formed Al-Zn-Mg-Cu alloy of 10 mm thickness by electron-beam welds . The microstructure and mechanical properties of the welding joint were investigated using optical microscope, scanning electron microscope, tensile test, microhardness etc.. The results indicated that the welding joint was comprised o...