Mapping and simulation of processing-induced mechanical strain in GaAs laser diodes.

We investigated the build-up of mechanical strain during the fabrication process of GaAs-based laser diodes. Test samples reproducing the geometrical features of the ridge waveguide, covered with metal thin films representative of the contact layer, were characterized by mapping the degree of polarization of the photoluminescence from the facet. Experimental maps of the strain distribution were produced and compared to finite element simulations.

Assessment of sestamibi CZT-SPECT reconstructed using deep-learning-based virtual attenuation correction maps according to coronary artery territory and with comparison to rubidium-PET.

Background: Attenuation artifacts affect the analysis of single-photon emission computed tomography (SPECT) myocardial perfusion imaging, especially in the right coronary artery (RCA) territory, although computed tomography (CT)-based attenuation corrections minimize this issue. This study aims to assess stress-rest [Tc]sestamibi cadmium zinc telluride (CZT)-SPECT reconstructed using deep-learning-based attenuation correction (DLAC) maps according to coronary artery territory and with comparison to [Rb]rubidium-positron emission tomography (Rb-PET) conventionally reconstructed with CT-based attenuation correction.

Methods: We compared stress-rest [Tc]sestamibi CZT-SPECT reconstructed without (i.

Diagnostic accuracy of low-dose myocardial perfusion imaging in a real-world setting.

Background: This large-scale study analyzes factors affecting the diagnostic accuracy of low-dose myocardial perfusion imaging and correlation with coronary angiography in a real-world practice.

Methods: We compared data extracted from routine reports of (i) low-dose [Tc]sestamibi stress-MPI performed with no attenuation correction and predominantly exercise stress testing and (ii) the corresponding coronary angiography.

Results: We considered 1070 pairs of coronary angiography/stress-MPI results reported by 11 physicians.

Towards a configurable and non-hierarchical search space for NAS.

Neural Architecture Search (NAS) outperforms handcrafted Neural Network (NN) design. However, current NAS methods generally use hard-coded search spaces, and predefined hierarchical architectures. As a consequence, adapting them to a new problem can be cumbersome, and it is hard to know which of the NAS algorithm or the predefined hierarchical structure impacts performance the most.

Association between baseline hemodynamic indices, cardiotoxicity risk, and survival in women with breast cancer.

Background: The outcome of breast cancer (BrCa) women monitored by low-dose equilibrium radionuclide angiography (ERNA) remains challenging to predict.

Aim: This study aims to determine whether heart rate (HR)/blood pressure (BP) ratio-based indexes, previously confirmed to predict outcomes of various diseases, also predict BrCa-therapy-related cardiotoxicity and survival.

Methods: Predictors of cardiotoxicity and survival were determined among pre-therapy variables, including shock index ([SI HR/systolic BP) and age-adjusted SI (ASI), in a female BrCa cohort with normal baseline ERNA-left ventricular ejection fraction (LVEF).

Routine first-line detection of breast cancer therapy-related cardiotoxicity by serial, fast and ultra-low-dose equilibrium radionuclide angiography.

Background: This study assesses a first-line left ventricular ejection fraction (LVEF) monitoring provided by an ultra-low-dose equilibrium radionuclide angiography (ERNA) in breast cancer women treated with potentially cardiotoxic drugs and analyzes patient outcome based on the ERNA results.

Methods: Breast cancer women treated with anthracyclines, followed or not by trastuzumab, were monitored using ERNA with a high-sensitivity CZT-camera. Calibrated LVEF measurements were obtained with an almost threefold reduction of radiation doses and 10-min recording times.

Assessment of the routine reporting of very low-dose exercise-first myocardial perfusion SPECT from a large-scale real-world cohort and correlation with the subsequent reporting of coronary stenosis at angiography.

Purpose: Our study assesses the routine reporting of exercise ischemia using very low-dose exercise-first myocardial perfusion SPECT in a large number of patients and under real-life conditions, by evaluating correlations with the subsequent routine reporting of coronary stenosis by angiography and with factors that predict ischemia.

Methods: Data from 13,126 routine exercise MPI reports, from 11,952 patients (31% women), using very low doses of sestamibi and a high-sensitivity cardiac CZT camera, were extracted to assess the reporting of significant MPI-ischemia (> 1 left ventricular segment), to determine the MPI normalcy rate in a group with < 5% pretest probability of coronary artery disease (CAD) (n = 378), and to assess the ability of MPI to predict a > 50% coronary stenosis in patients with available coronary angiography reports in the 3 months after the MPI (n = 713).

Results: The median effective patient dose was 2.

Bone Scintigraphy of Vertebral Fractures With a Whole-Body CZT Camera in a PET-Like Utilization.

An image display with a standardized uptake value (SUV) scale is recommended for analyzing PET exams, thus requiring the reconstruction of accurate images for both SUV measurement and visual analysis. This study aimed to determine whether such images may also be obtained with a high-speed CZT-SPECT/CT system, with a further application for the longitudinal monitoring of vertebral fractures. SPECT image reconstruction was optimized with an IEC phantom according to both image quality parameters and accuracy of measured activity.

Early 18F-FDG PET Flare-up Phenomenon After CAR T-Cell Therapy in Lymphoma.

18F-FDG PET/CT imaging series were acquired on a 64-year-old woman with refractory diffuse large B lymphoma to monitor chimeric antigen receptor (CAR) T-cell therapy. Because of a clinical deterioration, 18F-FDG PET/CT performed 8 days after CAR T-cell therapy suggested an early flare-up phenomenon with new lymph node involvement, lymph node progression while a decrease in metabolic tumor volume. The 18F-FDG PET/CT 1 month after CAR T-cell therapy confirmed this hypothesis.

Strong Electron-Phonon Interaction in 2D Vertical Homovalent III-V Singularities.

Highly polar materials are usually preferred over weakly polar ones to study strong electron-phonon interactions and its fascinating properties. Here, we report on the achievement of simultaneous confinement of charge carriers and phonons at the vicinity of a 2D vertical homovalent singularity (antiphase boundary, APB) in an (In,Ga)P/SiGe/Si sample. The impact of the electron-phonon interaction on the photoluminescence processes is then clarified by combining transmission electron microscopy, X-ray diffraction, calculations, Raman spectroscopy, and photoluminescence experiments.

Direct measurement of the spectral dependence of Lamb coupling constant in a dual frequency quantum well-based VECSEL.

Spectral dependence of Lamb coupling constant C is experimentally investigated in an InGaAlAs Quantum Wells active medium. An Optically-Pumped Vertical-External-Cavity Surface-Emitting Laser is designed to sustain the oscillation of two orthogonally polarized modes sharing the same active region while separated in the rest of the cavity. This laser design enables to tune independently the two wavelengths and, at the same time, to apply differential losses in order to extract without any extrapolation the actual coupling constant.

Head-to-head comparison of image quality between brain F-FDG images recorded with a fully digital versus a last-generation analog PET camera.

Background: The quality of phantom images was previously shown to be higher on digital (Vereos Philips®) compared to analog PET (Ingenuity Philips®) cameras. This study aimed to determine the extent to which this difference still remains significant on normal brain F-FDG PET images.

Methods: Relative noise and contrast as well as border sharpness (a spatial resolution index) of central (striata) and peripheral (occiput) gray-matter structures were compared between 10 sets of normal brain F-FDG PET images recorded and reconstructed on digital and analog last-generation PET cameras, together with a subjective visual analysis of image quality provided by experienced physicians.

Left ventricular ejection fraction determined with the simulation of a very low-dose CZT-SPECT protocol and an additional count-calibration on planar radionuclide angiographic data.

Purpose: To determine whether the left ventricular ejection fractions (EFs), measured on a high-sensitivity CZT single photon emission computed tomography (SPECT)-camera with a 70% reduction in recording times and a prevention of EF overestimation through an additional count-calibration, are concordant with reference EF from planar radionuclide angiography (2D-RNA).

Methods: An additional 10-minute CZT-SPECT recording was performed in patients referred to 2D-RNA for cardiomyopathy (n = 23) or chemotherapy monitoring (n = 50) with an in vivo red blood cell labeling with 850 MBq [Formula: see text]. The EF, obtained from CZT-SPECT with 100% (SPECT100) or 30% (SPECT30) projection times and with a SPECT-count calibration on the 2D-RNA counts of corresponding cavity volumes, were compared to EF from 2D-RNA.

High-Resolution Brain 18F-FDG Images Provided by Fully Digital PET.

Normal brain F-FDG PET images, consecutively recorded on analog and fully digital PET cameras in an 85-year-old woman, are depicted herein with the reconstruction methods recommended for a 2-mm voxel size on each camera and with a high-resolution reconstruction additionally developed for digital PET with a 1-mm voxel size. An enhanced gray-to-white matter contrast was consistently documented for digital PET when compared with analog PET, and was associated with a further enhancement in spatial resolution at 1-mm voxel size, as evidenced by a much clearer delineation of cortical gyri. These high-resolution images could favor the identification of brain abnormalities.

Assessment of Myocardial CZT SPECT Recording in a Forward-Leaning Bikerlike Position.

This prospective randomized study assessed myocardial perfusion imaging with the high-sensitivity D.SPECT cadmium-zinc-telluride camera in a forward-leaning bikerlike position, which may potentially lower diaphragmatic attenuation and reduce breathing-related cardiac motion, in a manner comparable to the prone position proposed with other SPECT cameras. Patients referred for a stress-rest Tc-sestamibi protocol and positioned in the biker position, with the chest leaning forward on the D.

Central Nervous System Myelomatosis Delineated by High-Resolution Brain Images From Fully Digital 18F-FDG PET.

Central nervous system myelomatosis is uncommon and is associated with a particularly poor prognosis. PET images, from a 53-year-old man referred to a fully digital F-FDG PET for relapsed multiple myeloma, revealed high F-FDG uptakes located in the cortex and sulci of the right central area and within the meningeal envelopes of the cerebellum, the trigeminal nerves, and on the spinal canal. These particular uptakes gave evidence of a central nervous system myelomatosis subsequently confirmed by plasma cells documented in cerebrospinal fluid.

Low-dose dual-isotope procedure planed for myocardial perfusion CZT-SPECT and assessed through a head-to-head comparison with a conventional single-isotope protocol.

Purpose Of The Report: This study aimed at assessing an original low-dose dual-isotope procedure in which the abnormal stress Tc-99m Sestamibi SPECT is followed by rest Tl-201 SPECT, along with a head-to-head comparison with a single-isotope procedure.

Methods And Results: One hundred two patients, referred for a low-dose stress-SPECT with Sestamibi (123 ± 20 MBq) on a CZT camera and for whom a rest Sestamibi SPECT was warranted, had an additional Tl-201 rest-SPECT (52 ± 5 MBq) between stress and rest Sestamibi SPECT recordings. Tl-201 images were processed for spill-over and scatter corrections, and uptake differences with stress Sestamibi SPECT were analyzed: (1) for rest acquisitions from Tl-201 (dual-isotope procedure) and from Sestamibi (single-isotope procedure) and (2) in segments for which a diagnosis of ischemia, infarct, or normal perfusion was achieved.

Aneurysmal angiosarcoma associated with vascular graft revealed by F-FDG-PET imaging.

We report a rare case of vascular graft-associated aneurysmal angiosarcoma by F-Fluorodeoxyglucose (FDG) positron emission tomography (PET). An 81-year-old male patient, with a prior history of graft interposition 1 year previously, was referred to F-FDG-PET because of an inflammatory syndrome of unknown origin. FDG-PET images revealed a particular pattern of intense circular uptake within the arterial wall (SUVmax = 10) in a popliteal aneurysm and, additionally, a large hypermetabolic mass centered by the graft.

Routine evaluation of left ventricular function using CZT-SPECT, with low injected activities and limited recording times.

Purpose: Gamma-cameras, with Cadmium-Zinc-Telluride (CZT) detectors, allow to perform myocardial perfusion imaging (MPI) with limited injected activities and recorded times. This study aimed at determining whether the routine assessment of left ventricular (LV) function with such limited counts protocols compares well with reference values from cardiac MRI.

Methods: The study included patients who have undergone cardiac MRI and an MPI routinely planned on a CZT camera with a low-dose protocol (120 MBq of Sestamibi for stress and 360 MBq at rest for 75 kg body weight), while targeting the recording of only 500 myocardial kcounts in order to limit the recording times (<10 minutes for stress, <4 minutes for rest).

Central pulse pressure is a determinant of heart and brain remodeling in the elderly: a quantitative MRI and PET pilot study.

Objective: The sustained elevation of blood pressure (BP) and especially of central pulse pressure (cPP) leads to heart and brain damage. This pilot study was aimed to precise the relationships between peripheral and central BP levels, and the remodeling of heart and brain as objectively quantified by cardiac MRI and brain F-fluorodeoxyglucose (FDG)-PET imaging in the elderly.

Methods: Twenty-eight apparently healthy elderly individuals (66-85 years old, 14 women) were prospectively recruited and allocated into two half groups, one with and one without hypertension, and all were referred for the quantitative determinations of peripheral and central BP using applanation tonometry, indexed left ventricular mass (per m of body surface area) using cardiac MRI, and brain metabolism with a voxel-based analysis of FDG-PET images adjusted for age and sex.

Stress-first protocol for myocardial perfusion SPECT imaging with semiconductor cameras: high diagnostic performances with significant reduction in patient radiation doses.

Purpose: Effective doses of 14 mSv or higher are currently being attained in patients having stress and rest myocardial perfusion imaging (MPI) single photon emission computed tomography (SPECT) performed on the same day with conventional protocols. This study aimed to assess the actual reduction in effective doses as well as diagnostic performances for MPI routinely planned with: (1) high-sensitivity cadmium zinc telluride (CZT) cameras, (2) very low injected activities and (3) a stress-first protocol where the normality of stress images may lead to avoiding rest imaging.

Methods: During a 1-year period, 2,845 patients had MPI on a CZT camera, a single-day stress-first protocol and low injected activities (120 MBq of (99m)Tc-sestamibi at stress for 75 kg body weight and threefold higher at rest).

Theoretical and experimental studies of (In,Ga)As/GaP quantum dots.

(In,Ga)As/GaP(001) quantum dots (QDs) are grown by molecular beam epitaxy and studied both theoretically and experimentally. The electronic band structure is simulated using a combination of k·p and tight-binding models. These calculations predict an indirect to direct crossover with the In content and the size of the QDs.