Once vascular access is made, then catheters are directed to the specific location to be imaged in the body by the use of guide wires. Such procedures might involve angioplasties where a balloon mechanism is placed across an area of narrowing, or stenosis, in a vessel or lumen. With controlled inflation of the balloon, the area of narrowing can be widened.
Often to keep these areas from narrowing again, stents can be placed within the lumen of the vessel or even in the trachea or oesophagus. Imaging in diagnostic or interventional procedures can be still images or motion cine images. In this type of imaging, images are taken at 2—30 frames per second to allow imaging of the flow of blood through vessels. A preliminary image of the area is taken before the contrast is injected. This technique requires the patient to remain motionless for optimal subtraction.
Angiograms can be performed of the heart to visualise the size and contractility of the chambers and anatomy of the coronary vessels. The thorax can also be studied to evaluate the pulmonary arteries and veins for vascular malformations, blood clots and possible origins of haemoptysis. The neck is often imaged to visualise the vessels that supply the brain as they arise from the aortic arch to the cerebral vessels, in the investigation of atherosclerotic disease, vascular malformations and tumoural blood supplies.
Renal artery imaging can elucidate the cause of hypertension in selected patients, as can imaging of the mesenteric vessels discover the origin of gastrointestinal bleeding or mesenteric angina. The CT image comprises a regular matrix of volumetric elements voxels. This value is compared with the attenuation value of water and is displayed on the Hounsfield scale.
No specific preparation is required for most CT examinations of the brain, spine or musculoskeletal system. Studies of the chest, abdomen and pelvis usually and those of the brain with complex histories require intravenous contrast medium that contains iodine, defining vascular relationships and discerning normal and pathological soft tissues to a greater extent. This is much less frequently performed with the latest generation of scanners that exquisitely differentiate different enhancing layers within the bowel wall.
CT colonography, in which the colon is pre-prepared with ingested contrast medium and insufflated with gas immediately prior to the scan, is also known as virtual colonscopy and has become an increasingly popular alternative procedure for bowel cancer screening in select patients. Generally all studies are performed with the patient supine, and images are obtained in the transverse or axial plain.
Modern CT scanners allow up to 25 degrees of gantry angulation, which is particularly valuable in spinal imaging. Occasionally, direct coronal images are obtained in the investigation of cranial and maxillofacial abnormalities; in these cases the patient lies prone with the neck extended and the gantry appropriately angled, but this technique has largely been superseded by the orthogonal imaging described above.
CT for the investigation of urinary tract calculi can be obtained in the prone position to show that a calculus is not lodged at the vesicoureteric junction, while CT colonography involves scanning in several different positions, e.
Magnetic resonance imaging MRI produces images by first magnetising the patient in the bore of a powerful magnet and then broadcasting short pulses of RF energy at Resonance of magnetically aligned spinning hydrogen nuclei protons occurs due to their behaviour akin to tiny bar magnets, aligning either with or against the magnetic field, producing a small net magnetic vector. Once the RF pulse is switched off, the protons flip back relax to their original position of equilibrium, emitting the RF energy they had acquired into the antenna around the patient, which is then amplified, digitised and, finally, spatially encoded by the array processor.
MRI systems are graded according to the strength of the magnetic field they produce. Open magnets for claustrophobic patients and limb scanners use permanent magnets between 0. MRI does not present any recognised biological hazard. Pillows containing metallic coiled springs have been known to near suffocate patients, and heavy floor buffing equipment has been found wedged in the magnet bore due to suboptimally informed domestic staff! Fluid is low signal. Fat suppression sequences using T2 fat saturation T2FS or short tau inversion recovery STIR are very sensitive in highlighting soft tissue or bone marrow oedema that almost invariably accompanies pathological states such as inflammation or tumour.
Metallic artefact reduction sequences MARS are superior in imaging periprosthetic soft tissues after joint replacement or other orthopaedic metalwork implantation. MR images have been acquired at 8 T of the microvasculature of the live human brain allowing close comparison with histology.
This has significant implications in the treatment of reperfusion injury and research into the physiology of solid tumours and angiogenesis. MRS assesses function within the living brain. Introduction — The role of imaging in teaching and diagnosis: technical aspects and applications MRS capitalises on the fact that protons residing in differing chemical environments possess slightly different resonant properties chemical shift.
For a given volume of brain the distribution of these proton resonances can be displayed as a spectrum. These different signals can be weighted to the smaller vessels, and hence closer to the active neurons, by using larger magnetic fields.
DTI will not accurately describe the microstructure in complex white matter voxels that contain more than one fibre population, due to intersecting tracts or to partial volume averaging of adjacent pathways with different fibre orientations, such as in the centrum semiovale, where major white matter tracts such as the pyramidal tract, the superior longitudinal fasciculus and the corpus callosum intersect.
This has hindered preoperative mapping of the pyramidal tract in brain tumour patients. Central nervous system tracts are not identifiable by direct examination, CT or conventional MRI scans, explaining the paucity of their description in neuroanatomy atlases and the poor understanding of their functions.
MRI sequences look at the symmetry of brain water diffusion. There is a direct relationship between the number of fibres and the degree of anisotropy. DTI assumes that the direction of least restriction corresponds to the direction of white matter tracts.
Diffusion MRI was introduced in , with the more recent evolution of the technique into DTI, where the relative mobility of the water molecules from the origin is modelled as an ellipsoid rather than a sphere, allowing full characterisation of molecular diffusion in the three dimensions of space and formation of tractograms. Barriers cause uneven anisotropic diffusion, and in white matter the principal barrier is the myelin axonal sheath.
Bundles of axons provide a barrier to perpendicular diffusion and a path for parallel diffusion along the orientation of the fibres. Anisotropic diffusion is expected to be increased overall in areas of high mature axonal order and conditions where barriers such as the myelin or the structure of the axon itself are disrupted, such as trauma; tumours and inflammation reduce anisotropy and yield DTI data used to seed various tractographic assessments of the brain, including development of arcuate and superior longitudinal fasciculi and corona radiata.
Data sets may be rotated continuously into various planes to better appreciate the structure, and colour can be assigned based on the dominant direction of the fibres. A leading clinical application of MRT is in the presurgical mapping of eloquent regions. Ultrasound Uniquely, ultrasound images do not depend on the use of electromagnetic wave forms.
A sound wave of appropriate frequency diagnostic range 3. As the beam passes through tissues, two important effects determine image production: attenuation and reflection. Attenuation is caused by the loss of energy due to absorption, reflection and refraction in soft tissues with resulting reduction in signal intensity. Reflection of sound waves within the range of the receiver produces the image, the echotexture of which is dependent upon tiny differences in acoustic impedance between different tissues.
Blood flow and velocity can be measured using the Doppler principle in duplex mode. These contrast agents clearly improve the detection of metastases in the liver and spleen. Ultrasound is the most common medical imaging technique for producing elastograms, in which stiffness or strain images of soft tissue are used to detect or classify tumours.
Cancer is 5—28 times stiffer than the background of normal soft tissue. When a mechanical compression or vibration is applied, the tumour deforms less than the surrounding tissue. Elastography can be used for example to measure the stiffness of the liver in vivo or in the detection of breast or thyroid tumours.
A correlation between liver elasticity and the cirrhosis score has been shown. Since that time, nuclear medicine has advanced and was recognised in the early s as a diagnostic subspeciality. Nuclear medicine, unlike diagnostic radiology which creates an image by passing energy through the body from an external source, creates an image by measuring the radiation emitted from tracers taken internally.
Overall the radiation dosages are comparable to CT and vary depending on the examination. The comprehensive appendix provides a glossary of MRI terms and radiology measurement tables. Key Points Concise overview of MRI for brain, chest and abdomen Features sections on MR cholangiopancreatography, MRI of the pelvis, and MR angiography Comprehensive appendix provides glossary of terms and radiology measurement tables Includes high quality MR images and tables illustrating complex anatomy.
It presents the normal appearances on the most frequently used imaging techniques, including conventional radiology, ultrasound, computed tomography, and magnetic resonance imaging. Similarly, all relevant body regions are covered: brain, spine, head and neck, chest, mediastinum and heart, abdomen, gastrointestinal tract, liver, biliary tract, pancreas, urinary tract, and musculoskeletal system.
The text accompanying the images describes the normal anatomy in a straightforward way and provides the medical information required in order to understand why we see what we see on diagnostic images. Helpful correlative anatomic illustrations in color have been created by a team of medical illustrators to further facilitate understanding. Building on the success of previous editions, this fully revised fifth edition provides a superb foundation for understanding applied human anatomy, offering a complete view of the structures and relationships within the body using the very latest imaging techniques.
It is ideally suited to the needs of medical students, as well as radiologists, radiographers and surgeons in training. It will also prove invaluable to the range of other students and professionals who require a clear, accurate, view of anatomy in current practice. Spratt, and Lonie Salkowski offer a complete and 3-dimensional view of the structures and relationships within the body through a variety of imaging modalities.
This atlas will widen your applied and clinical knowledge of human anatomy. Features orientation drawings that support your understanding of different views and orientations in images with tables of ossification dates for bone development. Presents the images with number labeling to keep them clean and help with self-testing. Reflects current radiological and anatomical practice through reorganized chapters on the abdomen and pelvis, including a new chapter on cross-sectional imaging.
Covers a variety of common and up-to-date modern imaging—including a completely new section on Nuclear Medicine—for a view of living anatomical structures that enhance your artwork and dissection-based comprehension. Includes stills of 3-D images to provide a visual understanding of moving images. It is important to know and understand the human anatomy in view of multitude of cross-sectional imaging in multiple planes.
It is meant for medical colleges, institutional and departmental libraries and for standalone MRI and orthopedic establishments. They will find the book extremely useful.
The tremendous advantages of the method consisting of safety, superb soft tissue contrast resolution, the ability to study flow, the ability to image in any plane or acquire data in 3D and an almost infinite array of sequences capable of distinguishing between disease and normal tissue, normal and abnormal blood flow make it incomparable for the diagnosis and study of multiple diseases and is particularly valuable in studying the heart and major vessels.
The authors of this book have understood that the secret of success of MR imaging in the study of the heart is to combine the knowledge of anatomy of the heart, the coronary vessels, the pericardium and large vessels with the intricacies of MR imaging. Building on the success of previous editions, this fully revised fifth edition provides a superb foundation for understanding applied human anatomy, offering a complete view of the structures and relationships within the body using the very latest imaging techniques.
It is ideally suited to the needs of medical students, as well as radiologists, radiographers and surgeons in training. It will also prove invaluable to the range of other students and professionals who require a clear, accurate, view of anatomy in current practice.
Imaging methods used to display normal human anatomy have improved dramatically over the last few decades. The ability to demonstrate the soft tissues by using the modern technologies of magnetic resonance imaging, X-ray computed tomography, and ultrasound has greatly facilitated our understanding of the link between anatomy as shown in the dissecting room and that necessary for clinical practice. This atlas has been produced because of the new technology and the fundamental changes that are occurring in the teaching of anatomy.
It enables the preclinical medical student to relate to basic anatomy while, at the same time, providing a comprehensive study guide for the clinical interpretation of imaging, applicable for all undergraduate and postgraduate levels. Several distinguished authors, experts in their fields of imaging, have contributed to Imaging Atlas of Human Anatomy 5th Edition PDF , which has benefitted from editorial integration to ensure balance and cohesion.
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