Contrast-enhanced MR angiography of the foot: anatomy and clinical application in patients with diabetes

International audienc

Acute chest pain with normal coronary angiogram: role of contrast-enhanced multidetector computed tomography in the differential diagnosis between myocarditis and myocardial infarction

[DOI:\hrefhttps://dx.doi.org/10.1097/RCT.0b013e318145219910.1097/RCT.0b013e3181452199] [PubMed:\hrefhttps://www.ncbi.nlm.nih.gov/pubmed/1837930718379307]International audienceTo evaluate the accuracy of delayed-enhanced multidetector computed tomography (MSCT) for differentiating between myocarditis and myocardial infarction in patients with normal x-ray coronary angiography.\ Twelve consecutive patients referred for acute chest pain and normal coronary arteries on x-ray coronary angiography were involved in this study. Delayed-enhanced MSCT and postgadolinium delayed-enhanced magnetic resonance imaging (MRI) examinations were performed within 36 hours and 4 days, respectively, after patient admission. Comparison between delayed-enhanced MSCT and MRI was performed by 3 independent blinded observers in term of final diagnosis, number of involved segments, and transmural extent.\ Final diagnosis between myocarditis and myocardial infarction was identical for delayed-enhanced MSCT and MRI with a significant agreement for number of involved segments and transmural extension. Interobserver reproducibility was good for both techniques.\ We demonstrated that delayed-enhanced MSCT allows differentiation between myocardial infarction and myocarditis with the same accuracy at acute phase compared with MRI

Contrast-enhanced MR angiography of the foot: anatomy and clinical application in patients with diabetes

[DOI:\hrefhttps://dx.doi.org/10.2214/ajr.182.6.182143510.2214/ajr.182.6.1821435] [PubMed:\hrefhttps://www.ncbi.nlm.nih.gov/pubmed/1514998715149987]International audienc

CARTILAGE THICKNESS MEASUREMENTS FROM PHOTO-COUNTING SPECTRAL COMPUTED TOMOGRAPHY IMAGES COMPARED WITH SYNCHROTRON RADIATION COMPUTED TOMOGRAPHY

International audienceImaging modalities which contribute to diagnosis, follow up and a better understanding of osteoarthritis are radiography, Magnetic Resonance Imaging (MRI), X-ray Computed tomography (CT), ultrasound, dual energy absorptiometry and positron emission tomography. Among these modalities, radiography is still the reference method to follow the cartilage impairment in osteoarthritis but only MRI and CT can provide three-dimensional images, MRI being more classically used in both clinical surveys and routine to visualize cartilage due to high contrast. Based on 3D MRI sequences, it is possible to perform 3D morphological maps for quantitative cartilage volume and thickness measurements. The best isotropic images that can be achieved with a 3T MR scanner is 0.63x0.63x0.68mm3 [1] and 0.3x0.3x0.3mm3 with a 7T MR scanner [2]. A new modality called Photo-Counting Spectral Computed Tomography (PCSCT) emerged recently with as main advantages to increase the resolution, the signal to noise ratio and the contrast in soft tissue compare to energy-integrating detectors that are classically used in routine CT device. From this new approach, we have shown in a previous study the interest of PCSCT virtual monoenergetic images at 60 keV for cartilage imaging [3].Zhang P et al. Clinical validation of the use of prototype software for automatic cartilage segmetation to qiantify knee cartilage in volunteers. BMC Musculoskeletal Disord. 23:19, 2022Bangarter N et al. Quantitative techniques for musculoskeletal MRI at 7 T. Quant Imaging med Surg 6:715,2016Chappard C et al. Virtual monoenergetic images from photon-counting spectral computed tomography to assess knee osteoarthritis. Eur Radio Exp, 22,6 202

Deep learning methods for virtual monoenergetic imaging from spectral CT

International audienceSpectral photon counting computed tomography (CT) is a X-ray imaging modality that acquires energy-resolved data thanks to photon counting detectors that sort photons depending on their energy. This allows to decompose the object into its material constituents or to reconstruct virtual monoenergetic images. In this paper, we address for the first time the reconstruction of virtual monoenergetic images from spectral CT measurements, which is a non linear inverse problem, focusing on the application to knee osteoarthrisis. While traditional methods are based on the inversion of a physical model, deep learning methods have recently demonstrated their ability to solve inverse problems. In this work, we propose several physics-informed deep learning strategies for virtual monoenergetic image reconstruction. We consider four different reconstruction algorithms for the recovery of virtual monoenergetic images in the projection and in the image domain. All of our algorithms include a variant of the U-net convolutional neural network. The proposed algorithms were trained and evaluated on the spectral CT data simulated from realistic knee phantoms generated from synchrotron radiation CT. They were also compared to a Gauss-Newton algorithm that minimized a cost function with a hand-crafted regularization term. Finally, our algorithms were applied to an experimental knee data set acquired on a clinical spectral CT scanner. We found that the proposed approaches provide virtual monoenergetic images with improved mean squared errors and structural similarities, compared to the Gauss-Newton method. Moreover, the image-domain network improved the mean squared error by a factor of two, compared to the projection-domain network. In both simulated and experimental data of osteoarthritis knees, we found that the cartilage was visible with naked eye on the virtual monoenergetic images reconstructed by our methods. The proposed deep learning networks outperformed the Gauss-Newton algorithm in the projection domain. Among deep reconstruction strategies, we found that the image-domain direct virtual monoenergetic reconstruction performs the best. They also allow for the direct visualization of the cartilage, which is essential for the assessment of cartilage integrity

CARTILAGE THICKNESS MEASUREMENTS FROM PHOTO-COUNTING SPECTRAL COMPUTED TOMOGRAPHY IMAGES COMPARED WITH SYNCHROTRON RADIATION COMPUTED TOMOGRAPHY

International audienceImaging modalities which contribute to diagnosis, follow up and a better understanding of osteoarthritis are radiography, Magnetic Resonance Imaging (MRI), X-ray Computed tomography (CT), ultrasound, dual energy absorptiometry and positron emission tomography. Among these modalities, radiography is still the reference method to follow the cartilage impairment in osteoarthritis but only MRI and CT can provide three-dimensional images, MRI being more classically used in both clinical surveys and routine to visualize cartilage due to high contrast. Based on 3D MRI sequences, it is possible to perform 3D morphological maps for quantitative cartilage volume and thickness measurements. The best isotropic images that can be achieved with a 3T MR scanner is 0.63x0.63x0.68mm3 [1] and 0.3x0.3x0.3mm3 with a 7T MR scanner [2]. A new modality called Photo-Counting Spectral Computed Tomography (PCSCT) emerged recently with as main advantages to increase the resolution, the signal to noise ratio and the contrast in soft tissue compare to energy-integrating detectors that are classically used in routine CT device. From this new approach, we have shown in a previous study the interest of PCSCT virtual monoenergetic images at 60 keV for cartilage imaging [3].Zhang P et al. Clinical validation of the use of prototype software for automatic cartilage segmetation to qiantify knee cartilage in volunteers. BMC Musculoskeletal Disord. 23:19, 2022Bangarter N et al. Quantitative techniques for musculoskeletal MRI at 7 T. Quant Imaging med Surg 6:715,2016Chappard C et al. Virtual monoenergetic images from photon-counting spectral computed tomography to assess knee osteoarthritis. Eur Radio Exp, 22,6 202

In vivo magnetic resonance imaging of large spontaneous aortic aneurysms in old apolipoprotein E-deficient mice

[PubMed:\hrefhttps://www.ncbi.nlm.nih.gov/pubmed/1537793715377937]International audienceOld ApoE-deficient mice were studied in vivo by magnetic resonance imaging (MRI) to prospectively evaluate vascular remodeling associated with atherosclerotic lesions.\ Old female ApoE-/- mice on a normal diet were followed by MRI at 2 Tesla for a 3-month period and killed for histopathology. Aortic dimensions were measured and compared.\ High-quality in vivo MR images were obtained at 2 Tesla with in plane spatial resolution of 86 X 86 microm2. On MRI, aortic lumen enlargement (>1.5-fold dilation) was seen in 10 of 13 mice, located predominantly in the suprarenal portion of the aorta. The mean maximal diameter of the aneurysms and of the aorta above and below the aneurysm were, respectively, 1.12 +/- 0.32 mm and 0.53 +/- 0.08 mm by MRI and 1.3+/- 0.41 mm and 0.55 +/- 0.15 mm by histology. Matched histologic cross-sections of the aortic wall showed medial degradation with rupture of the internal elastic lamina at multiple sites, associated with fibrolipidic plaque containing cholesterol crystals.\ Aortic lumen enlargement was diagnosed in old ApoE-/- mice at sites with advanced atherosclerotic plaques. MRI has potential both as an in vivo imaging technique for screening mouse models for vascular wall pathology and to follow arterial remodeling associated with the disease progression

Improved Peritoneal Cavity and Abdominal Organ Imaging Using a Biphasic Contrast Agent Protocol and Spectral Photon Counting Computed Tomography K-Edge Imaging

International audienceTo validate in vitro the capability of a high-spatial-resolution prototype spectral photon-counting computed tomography (SPCCT) scanner to differentiate between 2 contrast agents and to assess in vivo the image quality and the feasibility to image the peritoneal cavity in rats using the 2 contrast agents simultaneously within the vascular and peritoneal compartments.\ The authors performed SPCCT imaging (100 mAs, 120 kVp) with energy bin thresholds set to 30, 51, 64, 72, and 85 keV in vitro on a custom-made polyoxymethylene cylindrical phantom consisting of tubes with dilutions of both contrast agents and in vivo on 2 groups of adult rats using 2 injection protocols. Approval from the institutional animal ethics committee was obtained. One group received macrocylic gadolinium chelate intraperitoneal (IP) and iodine intravenous (IV) injections (protocol A, n = 3), whereas the second group received iodine IP and gadolinium IV (protocol B, n = 3). Helical scans were performed 35 minutes after IP injection and 20 seconds after IV injection. The SPCCT and contrast material images, that is, iodine and gadolinium maps, were reconstructed with a field of view of 160 mm, an isotropic voxel size of 250 μm, and a matrix size of 640 × 640 pixels using a soft reconstruction kernel. The SPCCT images were reconstructed with 2 different spatial resolutions to compare the image quality (sharpness, diagnostic quality, and organ visualization) of SPCCT (250 μm) with single-energy computed tomography (CT) (600 μm). Two radiologists evaluated the peritoneal opacification index in 13 regions (score = 0-3 per region) on each type of image. Concentrations of contrast agents were measured in the organs of interest.\ In vitro, the concentration measurements correlated well with the expected concentrations. The linear regressions both had R values of 0.99, slopes of 0.84 and 0.87, and offsets at -0.52 and -0.38 mg/mL for iodine and gadolinium, respectively. In vivo, the SPCCT images were of better diagnostic quality, with increased sharpness compared with the CT-like images (P < 0.0001). Intraperitoneal diffusion was excellent, with similar peritoneal opacification index on SPCCT images and overlay of contrast material maps (P = 1) without a significant difference between protocol A (37.0 ± 1.7) and protocol B (35.3 ± 1.5) (P = 0.34). Only the contrast material maps demonstrated clear visual separation of the contrast agents, allowing specific quantification of the physiological enhancement in the liver, spleen, and kidney and the urinary clearance in the renal pelvis and bladder. Renal excretion of the contrast agents injected IP was observed and was consistent with blood diffusion.\ Spectral photon-counting CT can be used to perform a complete peritoneal dual-contrast protocol, enabling a good assessment of the peritoneal cavity and abdominal organs in rats

Review of an initial experience with an experimental spectral photon-counting computed tomography system

Spectral photon-counting CT (SPCCT) is an emerging X-ray imaging technology that extends the scope of available diagnostic imaging tools. The main advantage of photon-counting CT technology is better sampling of the spectral information from the transmitted spectrum in order to benefit from additional physical information being produced during matter interaction, including photo-electric and Compton effects, and the K-edge effect. The K-edge, which is specific for a given element, is the increase in X-ray absorption of the element above the binding energy between its inner electronic shell and the nucleus. Hence, the spectral information contributes to better characterization of tissues and materials of interest, explaining the excitement surrounding this area of X-ray imaging. Other improvements of SPCCT compared with conventional CT, such as higher spatial resolution, lower radiation exposure and lower noise are also expected to provide benefits for diagnostic imaging. In this review, we describe multi-energy CT imaging, from dual energy to photon counting technology, and our initial experience results using a clinical-scale spectral photon counting CT (SPCCT) prototype system in vitro and in vivo. In addition, possible clinical applications are introduced