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CT Perspective of Normal Cardiovascular Anatomy
Published in Paul Schoenhagen, Frank Dong, Cardiac CT Made Easy, 2023
The image processing techniques most often used are 2-D multiplanar reformation (MPR) and maximum intensity projection (MIP), 3-D shaded surface display (SSD) and volume rendering (VR), and 4-D volume rendering.10 The quality of these reformatted images depends on the in-plane and through-plane spatial resolution. If the through-plane resolution or slice thickness is less than the in-plane resolution of axial images, oblique reformation will be associated with a loss of spatial resolution compared with axial images. It is also important to understand that advanced 3-D and 4-D displays of the CT data can be associated with loss of image detail. Therefore, experienced CT readers typically form their initial impression using the axial ‘source’ images and then supplement the review with advanced 3-D images.
Level Set Methods for Cardiac Segmentation in MSCT Images
Published in Ayman El-Baz, Jasjit S. Suri, Level Set Method in Medical Imaging Segmentation, 2019
Ruben Medina, Sebastian Bautista, Villie Morocho, Alexandra La Cruz
Early identification of myocardial muscle dysfunction by quantitative analysis allows a reliable diagnosis of cardiovascular diseases. The above analysis is based on the estimation of various clinical parameters including ventricular volumes, ejection fraction, thickening of the myocardium and myocardial mass. For the evaluation of such parameters it is generally required the proper delineation of endocardial and epicardial contours of cardiac cavities [1]. Quantification of cardiac function is usually performed using X-Rays 2-D contrast ventriculographic images, 2-D or 3-D echocardiographic images, 4-D MRI images, 4-D Multi–Slice CT (MSCT) or PET/SPECT images. Multi-Slice CT is a medical imaging modality that enables acquisition of 3-D or 4-D cardiac images including more than 20 3-D images per cardiac cycle. A key task to achieve cardiac quantification is accurate detection of the left ventricle in the MSCT images, which can be performed by means of a segmentation process. The segmentation is based on grouping of pixels/voxels in an image for representing a shape, where the procedure used for attaining this organization is based on proximity and similarity between attributes of an image [2,3]. The segmentation of cardiac images is a difficult task because of several problems such as: 1) complexity and variability of the heart movement; 2) the low contrast exhibiting by the objects in these images; 3) contamination with noise; and 4) presence of artifacts that may arise during the acquisition and / or reconstruction of the images [4].
Regenerative Orthopedics Enabled by Cross-Cutting Technologies
Published in Kohlstadt Ingrid, Cintron Kenneth, Metabolic Therapies in Orthopedics, Second Edition, 2018
The use of ultrasound guided injection has become the gold standard for the application of orthobiologics. Fortunately, a desire to improve image quality is pushing ultrasound manufacturers beyond the capabilities of traditional 2-D imaging and increasing the roll-out of 3-D and even 4-D ultrasound systems. The b-mode technology has improved enormously in terms of transducer sensitivity, the beam former, image processing speed, and the quality of the final data display. Volumetric ultrasound has also continued to improve. Transducers now allow for the acquisition of real-time volumes of tissue allowing us to image in multiple planes – for example, the transverse and sagittal dimensions – simultaneously. Sonoelastography measures the mechanical characteristics of tissues and then displays those mechanical characteristics overlaid on the conventional b-mode ultrasound image, giving physicians the ability to see stiffer and softer areas inside the tissue. As this technology continues to improve, it will enhance the accuracy, effectiveness, and outcomes of the application of these orthobiologic treatments.
Planning target volume density impact on treatment planning for lung stereotactic body radiation therapy
Published in Acta Oncologica, 2021
Milovan Savanović, Dražan Jaroš, Jean-Noël Foulquier
CT acquisition was performed using a GE LightSpeed scan with 16 slices (General Electric Medical Systems, Waukesha, WI, USA), equipped with the Real-Time Positioning Management system (RPM, Varian Medical Systems, Palo Alto, CA, USA). Following institutional protocol, lung SBRT patients were scanned with two helical CT scans, with and without a stereotactic body frame. This was followed by a 4 D-CT scan, using the following parameters: 0.7 s/rotation period, 120 kV, mA ranging from 10 to 440 mA, 16 slices detector and a slice thickness of 1.25 mm, with a beam collimation width of 20 mm, and field of view (FOV) of 55 cm. The tube current modulation (TCM) was turned on. The 4 D-CT scan was acquired in retrospective mode. The 4 D images were reconstructed retrospectively, in ten phases that ranged from 0 to 90%, with increments of 10%.
CyberKnife radiation therapy as a platform for translational mouse studies
Published in International Journal of Radiation Biology, 2021
Martha Kiljan, Sabrina Weil, Andres Vásquez-Torres, Meike Hettich, Marimel Mayer, Olta Ibruli, Matthias Reinscheid, Isabelle Heßelmann, Jiali Cai, Li-na Niu, Yagmur Sahbaz, Christian Baues, Wolfgang W. Baus, Florian Kamp, Simone Marnitz, Grit S. Herter-Sprie, Jan M. Herter
The extent of respiratory motion of the tumor is included within the GTV: Mice have a physiological respiratory rate of 100–200 breaths/minute at rest which does not change during CT acquisition. Therefore, the tumor imaging results in a cumulative (pseudo) 4 D scan. Contouring the tumor on the CT scan, the GTV will thus include the breathing motion, very much like an artifical ‘Internal Target Volume’ (ITV). Initially, we added a PTV to ensure that we hit the target sufficiently as we were initially unsure how precisely our approach would work in mice, given that the system was not built for mice. This was gradually decreased: Based on the presented data, we are confident that we are able to apply a highly precise dose to the target with zero PTV margin.
Ulcerative colitis: understanding the impact of ulcerative colitis on everyday life and exploring the unmet needs of patients
Published in Current Medical Research and Opinion, 2021
Philip O’Hagan, Jimmy Limdi, Ayesha Akbar, Seb Tucknott, Durgesh Nandini Kahol
Since the primary objective of the study was to gain an in-depth understanding of UC from the patient’s perspective, interviews were based on the use of 4-D patient mapping as a framework. This biopsychosocial model of disease19 is unlike other more traditional biomedical modelling approaches. It recognises that in order to arrive at a rational treatment, physicians must take into account not just the physical determinants of the disease but also the psychological and social status of the patient and crucially, the role of the healthcare system particularly that of the physician.