Amir Pourmorteza

Bio: Amir Pourmorteza is an academic researcher from Emory University. The author has contributed to research in topics: Photon counting & Imaging phantom. The author has an hindex of 19, co-authored 43 publications receiving 1179 citations. Previous affiliations of Amir Pourmorteza include Johns Hopkins University & Johns Hopkins University School of Medicine.

Photon-counting CT: Technical Principles and Clinical Prospects.

Abstract: Photon-counting CT is an emerging technology with the potential to dramatically change clinical CT Photon-counting CT uses new energy-resolving x-ray detectors, with mechanisms that differ substantially from those of conventional energy-integrating detectors Photon-counting CT detectors count the number of incoming photons and measure photon energy This technique results in higher contrast-to-noise ratio, improved spatial resolution, and optimized spectral imaging Photon-counting CT can reduce radiation exposure, reconstruct images at a higher resolution, correct beam-hardening artifacts, optimize the use of contrast agents, and create opportunities for quantitative imaging relative to current CT technology In this review, the authors will explain the technical principles of photon-counting CT in nonmathematical terms for radiologists and clinicians Following a general overview of the current status of photon-counting CT, they will explain potential clinical applications of this technology

Abdominal Imaging with Contrast-enhanced Photon-counting CT: First Human Experience

Abstract: The photon-counting detector system showed equivalent performance to clinical energy-integrating detectors when the abdomen was evaluated in a conventional scanning mode with the added advantage of providing spectral information that may be used for material decomposition.

Photon-counting CT for simultaneous imaging of multiple contrast agents in the abdomen: An in vivo study

Abstract: Purpose To demonstrate the feasibility of spectral imaging using photon-counting detector (PCD) x-ray computed tomography (CT) for simultaneous material decomposition of three contrast agents in vivo in a large animal model. Methods This Institutional Animal Care and Use Committee-approved study used a canine model. Bismuth subsalicylate was administered orally 24–72 h before imaging. PCD CT was performed during intravenous administration of 40–60 ml gadoterate meglumine; 3.5 min later, iopamidol 370 was injected intravenously. Renal PCD CT images were acquired every 2 s for 5–6 min to capture the wash-in and wash-out kinetics of the contrast agents. Least mean squares linear material decomposition was used to calculate the concentrations of contrast agents in the aorta, renal cortex, renal medulla and renal pelvis. Results Using reference vials with known concentrations of materials, we computed molar concentrations of the various contrast agents during each phase of CT scanning. Material concentration maps allowed simultaneous quantification of both arterial and delayed renal enhancement in a single CT acquisition. The accuracy of the material decomposition algorithm in a test phantom was −0.4 ± 2.2 mM, 0.3 ± 2.2 mM for iodine and gadolinium solutions, respectively. Peak contrast concentration of gadolinium and iodine in the aorta, renal cortex, and renal medulla were observed 16, 24, and 60 s after the start each injection, respectively. Conclusion Photon-counting spectral CT allowed simultaneous material decomposition of multiple contrast agents in vivo. Besides defining contrast agent concentrations, tissue enhancement at multiple phases was observed in a single CT acquisition, potentially obviating the need for multiphase CT scans and thus reducing radiation dose.

Feasibility of Dose-reduced Chest CT with Photon-counting Detectors: Initial Results in Humans.

Abstract: This feasibility study demonstrated good diagnostic quality, noise power spectrum, and lung nodule contrast-to-noise ratio with dose-reduced photon-counting detector chest CT compared with those attained with conventional energy-integrating detector CT.

Photon-Counting Computed Tomography for Vascular Imaging of the Head and Neck: First In Vivo Human Results

Abstract: PurposeThe purpose of this study was to evaluate image quality of a spectral photon-counting detector (PCD) computed tomography (CT) system for evaluation of major arteries of the head and neck compared with conventional single-energy CT scans using energy-integrating detectors (EIDs).MethodsIn this

Photon-counting CT: Technical Principles and Clinical Prospects.

Abstract: Photon-counting CT is an emerging technology with the potential to dramatically change clinical CT Photon-counting CT uses new energy-resolving x-ray detectors, with mechanisms that differ substantially from those of conventional energy-integrating detectors Photon-counting CT detectors count the number of incoming photons and measure photon energy This technique results in higher contrast-to-noise ratio, improved spatial resolution, and optimized spectral imaging Photon-counting CT can reduce radiation exposure, reconstruct images at a higher resolution, correct beam-hardening artifacts, optimize the use of contrast agents, and create opportunities for quantitative imaging relative to current CT technology In this review, the authors will explain the technical principles of photon-counting CT in nonmathematical terms for radiologists and clinicians Following a general overview of the current status of photon-counting CT, they will explain potential clinical applications of this technology

The evolution of image reconstruction for CT—from filtered back projection to artificial intelligence

Abstract: The first CT scanners in the early 1970s already used iterative reconstruction algorithms; however, lack of computational power prevented their clinical use. In fact, it took until 2009 for the first iterative reconstruction algorithms to come commercially available and replace conventional filtered back projection. Since then, this technique has caused a true hype in the field of radiology. Within a few years, all major CT vendors introduced iterative reconstruction algorithms for clinical routine, which evolved rapidly into increasingly advanced reconstruction algorithms. The complexity of algorithms ranges from hybrid-, model-based to fully iterative algorithms. As a result, the number of scientific publications on this topic has skyrocketed over the last decade. But what exactly has this technology brought us so far? And what can we expect from future hardware as well as software developments, such as photon-counting CT and artificial intelligence? This paper will try answer those questions by taking a concise look at the overall evolution of CT image reconstruction and its clinical implementations. Subsequently, we will give a prospect towards future developments in this domain. KEY POINTS: • Advanced CT reconstruction methods are indispensable in the current clinical setting. • IR is essential for photon-counting CT, phase-contrast CT, and dark-field CT. • Artificial intelligence will potentially further increase the performance of reconstruction methods.

Photon-counting Detector CT: System Design and Clinical Applications of an Emerging Technology

Abstract: Photon-counting detector (PCD) CT is an emerging technology that has shown tremendous progress in the last decade. Various types of PCD CT systems have been developed to investigate the benefits of this technology, which include reduced electronic noise, increased contrast-to-noise ratio with iodinated contrast material and radiation dose efficiency, reduced beam-hardening and metal artifacts, extremely high spatial resolution (33 line pairs per centimeter), simultaneous multienergy data acquisition, and the ability to image with and differentiate among multiple CT contrast agents. PCD technology is described and compared with conventional CT detector technology. With the use of a whole-body research PCD CT system as an example, PCD technology and its use for in vivo high-spatial-resolution multienergy CT imaging is discussed. The potential clinical applications, diagnostic benefits, and challenges associated with this technology are then discussed, and examples with phantom, animal, and patient studies are provided. ©RSNA, 2019.

Dual-Energy CT: New Horizon in Medical Imaging.

Abstract: Dual-energy CT has remained underutilized over the past decade probably due to a cumbersome workflow issue and current technical limitations Clinical radiologists should be made aware of the potential clinical benefits of dual-energy CT over single-energy CT To accomplish this aim, the basic principle, current acquisition methods with advantages and disadvantages, and various material-specific imaging methods as clinical applications of dual-energy CT should be addressed in detail Current dual-energy CT acquisition methods include dual tubes with or without beam filtration, rapid voltage switching, dual-layer detector, split filter technique, and sequential scanning Dual-energy material-specific imaging methods include virtual monoenergetic or monochromatic imaging, effective atomic number map, virtual non-contrast or unenhanced imaging, virtual non-calcium imaging, iodine map, inhaled xenon map, uric acid imaging, automatic bone removal, and lung vessels analysis In this review, we focus on dual-energy CT imaging including related issues of radiation exposure to patients, scanning and post-processing options, and potential clinical benefits mainly to improve the understanding of clinical radiologists and thus, expand the clinical use of dual-energy CT; in addition, we briefly describe the current technical limitations of dual-energy CT and the current developments of photon-counting detector

Photon-counting CT review

Abstract: Photon-counting detectors are a promising new technology for computed tomography (CT) systems. They provide energy-resolved CT data at very high spatial resolution without electronic noise and with improved tissue contrasts. This review article gives an overview of the principles of photon-counting detector CT, of potential clinical benefits and limitations, and of the experience gained so far in pre-clinical installations.