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How to Utilize Coronary Computed Tomography Angiography in the Treatment of Coronary Artery Disease
摘要： Coronary computed tomography angiography (CCTA) has high negative predictive power for detecting coronary artery disease. However CCTA is limited by moderate positive predictive power in the detection of myocardial ischemia. This is not unexpected because the diameter of a stenosis is a poor indicator of myocardial ischemia and discrepancy between the severity of stenosis and noninvasive tests is not uncommon. The value of stenosis for predicting future development of acute coronary syndrome represented by plaque rupture has been questioned. CCTA identifies the characteristics of high-risk plaque including positive remodeling, low density plaque and spotty or micro-calcification. Also, additional evaluation of myocardial ischemia using computational flow dynamics, and luminal attenuation gradient are expected to increase both diagnostic performance for hemodynamically significant stenosis and the predictive power for future cardiovascular risk. Technical advances in CCTA would enable evaluation of both coronary artery stenosis and myocardial ischemia simultaneously with high predictive performance, and would improve vastly the clinical value of CCTA.
关键词： Functional ischemia,Coronary artery disease,Atherosclerosis,Prognosis,Coronary CT angiography,Myocardial mass
更新于2025-09-23 15:22:29
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Design and performance evaluation of high resolution small animal PET scanner based on monolithic crystal: a simulation study
摘要： Dedicated small-animal PET scanners functionality can be optimized by improving the sensitivity and spatial resolution of the scanner. Approximately most of the developed and commercially available small-animal PET scanners are equipped with pixelated scintillators; therefore, their spatial resolution is limited to the crystal pixel size. Complex fabrication, low-sensitivity, and disability in depth of interaction calculation (DOI) are the major disadvantages of pixelated crystals. However, monolithic scintillator crystals are known as one of the most commonly used substitutions, as they have higher sensitivity, DOI recognition, and lower cost. We already designed and implemented a dedicated small-animal PET scanner based on pixelated scintillator crystals and silicon photomultiplier (SiPM). In this study, we plan to present a new optimized design based on the monolithic crystal, with similar performance by the previous scanner. Then we would optimize the thickness of the monolithic crystals for animal PET scanners as a function of sensitivity and spatial resolution. All simulations were performed based on GEANT4, a validated Monte Carlo toolkit. We simulated a recently fabricated scanner with pixelated crystals and compared it with a simulated scanner based on an optimized monolithic crystal. The experimental setup used for comparison and validation is a small Animal PET consisting of ten pixelated modules. This study anticipates that by replacing a pixelated crystal (consist of 24 × 24 LYSO elements, and 2 × 2 × 10 mm3 crystal size) with a monolithic crystal (with 8 mm thickness and 50.2 × 50.2 entrance area), the average spatial resolution stays the same and sensitivity grows ～ 17% in the center of AFOV and also the fabrication cost dives remarkably. Simulation reveals that although the depth of interaction DOI was not taken into consideration, the crystals with 6 mm thickness have acceptable spatial resolution (～ 1.3 mm FWHM at the centre of the AFOV) and relatively good absolute sensitivity (～ 1.6%).
关键词： SPECT,coronary CT angiography (CTA),PET PET/CT,Gamma camera,Models and simulations
更新于2025-09-23 15:22:29
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256-Slice Coronary Computed Tomography Angiography Using Low Tube Voltage of 100 KV
摘要： Purpose: To evaluate the image quality and radiation dose of 100 kV with 1000 mAs retrospective electrocardiography (ECG)-gated CCTA protocol, compared to the standard protocol of 120 kV with 800 mAs retrospective ECG-gated CCTA. Material and Methods: We divided 70 patients into two, a reduced dose group with 35 patients (18 M, 17 F; Mean age 56.94 ± 11.51 years) were examined by 100-kV with 1000 mAs retrospective ECG-gated CCTA, and another as a standard group of 35 patients (21, 14 F; Mean age 54.03 ± 9.81 years) were examined by 120-kV with 800 mAs retrospective ECG-gated CCTA. The two blinded radiologists analyzed the image quality of the coronary arteries independently and they accessed subjective and objective image quality. The radiation dose was also measured as effective radiation dose [ED] and was calculated using CT dose volume index [CTDIvol.], dose-length product [DLP] and conversion coefficient for chest (conversion factor k=0.014 mSv mGy-1cm-1). Results: Although the objective image quality of the 100-kV with 1000 mAs was significantly better than the 120-kV with 800 mAs (mean SNR, 36.65 ± 2.95 vs. 33.47 ± 3.86, P<0.0001; mean CNR, 34.27 ± 2.92 vs. 30.62 ± 3.90, P<0.0001). There was no significant variation in the subjective image quality between two groups (mean image score, 4.54 ± 0.37 vs. 4.56 ± 0.25 for radiologist 1, P = 0.781; 4.52 ± 0.25 vs. 4.56 ± 0.25 for radiologist 2, P=0.486). The radiation dose was found to be reduced by 28% with the 100-kV/1000 mAs protocol than with the 120-kV/800 mAs retrospective ECG-gated CCTA (7.87 ± 0.59 vs. 10.95 ± 1.67 mSv, P<0.0001). Conclusion: The protocol of low tube voltage CCTA using 100 kV/1000 mAs retrospective ECG-gated shows significant reduction of the radiation dose without disturbing the subjective image quality of CCTA.
关键词： Coronary CT angiography,Image quality,Radiation dose
更新于2025-09-23 15:21:21
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Technical Aspects, Interpretation, and Body of Evidence for Coronary Computed Tomography Angiography
摘要： Coronary computed tomography angiography has high sensitivity for the detection of coronary stenosis and excellent negative predictive value to rule out stenosis. Due to rapid technical developments, images of excellent quality are obtained with rare artifacts and low radiation doses. Recently established and updated guidelines provide guidance through coronary interpretation with structured and consistent reporting.
关键词： Coronary interpretation,Coronary stenosis,Coronary CT angiography,Emergency department
更新于2025-09-23 15:21:01
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Characterization of monolithic GAGG:Ce coupled to both PMT and SiPM array for gamma imaging in Nuclear Medicine
摘要： GaGG:Ce scintillation crystal is very useful for nuclear imaging purposes, thanks to its several advantages (high density, short decay time, high light yield and good energy resolution, no self-activity, no hygroscopic). However, only the recent improvements in the growth processes make it available with large size, in order to use it in monolithic configuration. The main drawbacks of pixelated crystals, as non-uniform response, high production costs and optical light loss, could be therefore overcome. In this work the characterization of this promising crystal coupled both to a single channel PMT (spectrometric purpose) and to a new technology SiPM (50% PDE and 74% geometrical fill factor) has been performed. The detection efficiency results good both for SPECT (87% at 122 keV) and for PET (18% at 356 keV) applications. However, the unexpected result arises from the energy resolution: at 356 keV 8.9% and 8.0% for single channel PMT and SiPM configuration, respectively. In other terms, the used SiPM allows to achieve higher energy resolution than single channel PMT. Moreover, a high imaging performance has been observed, with a millimeter intrinsic spatial resolution.
关键词： SPECT,PET PET/CT,Gamma camera,Intra-operative probes,Scintillators and scintillating fibres and light guides,coronary CT angiography (CTA),Scintigraphy and whole-body imaging
更新于2025-09-23 15:21:01
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Fast and efficient detection of 511 keV photons using Cherenkov light in PbF <sub/>2</sub> crystal, coupled to a MCP-PMT and SAMPIC digitization module
摘要： We study the possibility to use the Cherenkov light for the e?cient detection of 511 keV photons with the goal to use it in TOF-PET. We designed and tested two detection modules consisting of PbF2 crystals attached to Planacon MCP-PMT XP85012. Ampli?ed PMT signals are digitized by the SAMPIC module with high readout rate, up to 105 events/s, and a negligible contribution to the time resolution, below 20 ps (FWHM). We developed a fast 2D scanning system to calibrate the PMT time response and studied in details the timing characteristics of the Planacon PMT. Using a radioactive 22Na source we measured a detection e?ciency of 24% for 511 keV photons in a 10 mm thick crystal and a coincidence resolving time of 280 ps. We analyzed the main factors limiting the time resolution of the large-surface detection module and proposed solutions to improve it, which will be tested in our future project.
关键词： Photon detectors for UV, visible and IR photons (vacuum) (photomultipliers, HPDs, others),Cherenkov and transition radiation,Gamma camera, SPECT, PET PET/CT, coronary CT angiography (CTA)
更新于2025-09-23 15:19:57
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Feasible scan timing for 320-row coronary CT angiography generated by the time to peak in the ascending aorta
摘要： Purpose: A 320-row CT scanner can briefly scan the entire heart. Therefore, the feasible scan timing is required. The aim of this study was to propose a refined method for feasible scan timing for coronary CT angiography (CCTA) using a time-density curve of the ascending aorta (AAo). Methods: One-hundred and twenty-nine patients were prospectively enrolled. All patients were performed test-bolus method. For the initial 65 patients, the scan timing was determined as a 3.0 s delay at the peak time in the AAo, which was defined as the conventional protocol (COV-P). For the next 64 patients, a scan timing of 1.0, 3.0, or 5.0 s delay was determined according to the interval from the contrast media arrival to peak time in the AAo, which was defined as the arrival to peak protocol (AP-P). The optimal scan timing was identified by the measurement of CT number in the left atrium, left ventricle, AAo, and descending aorta. The coronary enhancement and heterogeneity were compared between the two protocols. Results: The optimal scan timing was significantly higher in the AP-P than in the COV-P (85.9% vs. 61.5%, p = 0.0017). The CT number in the left circumflex artery (LCX) was significantly higher in the AP-P than the COV-P (344.5 Hounsfield units vs. 316.3 Hounsfield units, p = 0.0484). The heterogeneous index of the LCX was significantly greater for the COV-P than the AP-P (?36.8 vs. –25.8, p = 0.0028). Conclusions: The AP-P can be used to determine the optimal scan timing for CCTA and contributes to stable coronary enhancement.
关键词： Coronary CT angiography,Feasible scan timing,320-row CT
更新于2025-09-19 17:15:36
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Coronary computed tomography: current role and future perspectives for cardiovascular risk stratification
摘要： Coronary computed tomography: current role and future perspectives for cardiovascular risk stratification. F. Musella, R. Formisano, G. Mattiello, E. Iardino, L. Petraglia, A. Vitagliano, I. Fabiani, A.P. Cirillo, M. Petito, P. Perrone-Filardi. Atherosclerotic coronary artery disease (CAD) is a major cause of morbidity and mortality. The majority of cardiovascular events, more than 50% of CAD deaths, occur in previously asymptomatic individuals at intermediate cardiovascular risk, highlighting the relevance of accurate individual risk assessment to decrease cardiovascular events through more appropriate targeting of preventive measures. In the last decades, the development of non-invasive imaging techniques have prompted interest in imaging of atherosclerosis. Coronary computed tomography provides the opportunity to assess the deposition of calcium in the coronary tree and to non-invasively image coronary vessels. Both information are useful for risk stratification of asymptomatic subjects or of subjects with suspected CAD.
关键词： cardiovascular imaging,coronary artery disease,coronary calcium score,atherosclerosis,coronary CT angiography.
更新于2025-09-10 09:29:36
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Compton camera based on Timepix3 technology
摘要： The Compton camera concept is based on the reconstruction of recorded Compton scattering events of incoming gamma rays. The scattering of primary gamma ray occurs in the first detector (called scattering detector — usually thin) recording the position and energy of the recoiled electron. The scattered gamma quantum continues towards the second detector (called absorption detector - usually thick) where it is absorbed. The second detector records the energy and the position of this scattered gamma. Using the Compton scattering equation it is possible to determine the scattering angle, and estimate possible directions of the original gamma ray as a surface of a cone. When the Compton camera records the number of such events, the location and the shape of the gamma source can be reconstructed. Timepix3, a hybrid single photon counting imaging pixel detector, is a perfect device for creation of a compact Compton camera. Timepix3 is an event based readout chip (every hit pixel is immediately sent to a readout) and can record the time-of-arrival (ToA) and energy of an incident gamma simultaneously in each pixel. The chip offers high energy resolution (1 keV at 60 keV, 7 keV at 356 keV), as well as time resolution (1.6 ns). The Timepix3 readout chip can be combined with different sensor materials (Si, CdTe, CZT). In this contribution, we present a very compact detector system for imaging with gamma-rays using the Compton camera principle. The system consists of at least two layers of hybrid pixel detectors Timepix3 with the sensors being optimized for gamma-ray tracking. The front detector layer (scattering) is made of silicon of 1 mm thickness, while the last layer (absorbing) is equipped with thick CdTe or CZT sensors up to 2 mm in thickness. The total absorption of the whole detector can be very high if several CdTe or CZT layers are used. The maximal number of layers is not limited, but the practical evaluation was performed with 2 layers. Thanks to Timepix3 simultaneous measurement of ToA and energy, it is possible to precisely detect coincidence events in the detector layers. Based on the energy and position of these events, it is possible to estimate the possible direction of the original gamma. The angular resolution of the presented Compton camera depends on the detected energy, and it is in the order of 1 degree.
关键词： PET PET/CT,coronary CT angiography (CTA),Gamma camera,Particle tracking detectors,Compton imaging,SPECT
更新于2025-09-09 09:28:46
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Simulation and evaluation of high-performance cost-effective positron emission mammography scanner
摘要： Breast cancer is the main cause of tumor deaths in women, thus several imaging modalities have been introduced recently to better diagnose the disease. New breast cancer cases were estimated to reach up to 246,660 in 2017, and the mortality rate was above 40,000. Early diagnosis is widely approved as being essential for an e?ective treatment and it also helps to reduce the incidences and mortality rates. Positron Emission Mammography (PEM) is a breast-dedicated imaging device which uses a pair of annihilation gamma photons to detect abnormalities in the breast tissue. PEM device is compact in nature with a reduced ?eld of view to cover the entire breast region, and it employs few detector modules which makes it cost-e?cient. To e?ectively diagnose breast cancer at a very early stage, a device with high spatial resolution and high sensitivity is required. PEM detectors based on semiconductor materials are characterized by an excellent intrinsic spatial resolution but are not cost-e?ective, whereas detectors based on scintillator crystals are cost-e?ective but have limited intrinsic resolution to detect small breast lesions. This study focuses on improving the resolution of scintillator detectors by simulating a PEM scanner employing 1 × 1 × 10 mm3 laser processed scintillator crystal. The simulation was done with a GEANT4 application for emission tomography (GATE) software, and performance evaluation tests were carried out according to the National Electrical Manufacturers Association (NEMA) standards. The scanner geometry has 90 mm transaxial ?eld of view (FOV) and 105 mm axial FOV. Evaluation results showed that the scanner has 10.6% system sensitivity, 1.0 mm spatial resolution at the center of the FOV (CFOV) and at 2.5 cm transaxial direction. The resolution at the axial 2.5 cm position is 2.1 mm. NEMA image quality test and Derenzo phantom study showed that the scanner can easily resolve 1 mm in diameter hot rods.
关键词： PET PET/CT,X-ray mammography and scinto- and MRI-mammography,coronary CT angiography (CTA),Gamma camera,SPECT
更新于2025-09-09 09:28:46