Lecture Notes Radiology Pradip R. Patel Consultant Radiologist Kingston Hospital London Third Edition First edition awarded BMA Book Award A John Wiley & Sons, Ltd., Publication This edition fi rst published 2010, © 2010 by P. R. Patel Previous editions: 1998, 2005 Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing programme has been merged with Wiley’s global Scientifi c, Technical and Medical business to form Wiley-Blackwell. 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Radiography, Medical–Outlines, syllabi, etc. I. Title. II. Title: Radiology. [DNLM: 1. Technology, Radiologic–methods. 2. Diagnostic Imaging–methods. WN 160 P295L 2010] RC78.17.P385 2010 616.07'57–dc22 2010008385 A catalogue record for this book is available from the British Library. Set in 8 on 12 pt Stone Serif by Toppan Best-set Premedia Limited Printed in Singapore 1 2010 Contents Preface, iv 1 Introduction, 1 2 Respiratory tract, 19 3 Cardiovascular system, 65 4 Gastrointestinal tract, 91 5 Liver and pancreas, 139 6 Urinary tract, 163 7 Musculoskeletal system, 197 8 Trauma, 227 9 Paediatrics, 249 10 Obstetrics and gynaecology, 259 11 Neuroradiology, 273 12 Specifi c radiological investigations, 303 13 Film-viewing hints, 309 Index, 315 iii Preface This book is intended to be a concise intro- increasing, so the format of the book is ductory guide to radiology, principally for arranged such that it can be covered within medical students, but it should also be of a short space of time. The clinical orienta- value to radiographers and junior doctors. tion should ensure that the importance of The contents cover the imaging techniques, radiology is not taken out of context with basic fi lm interpretation and specialized the routine care of patients, serving also as radiological investigations currently avail- an aid to reinforce some essential back- able. Emphasis is on conventional plain ground information. fi lm and contrast radiology, as it is essential The book is divided into sections by that interpretation of these fundamentals body systems, with a brief description of is mastered before progressing to more techniques and investigations given at the advanced imaging techniques, such as com- beginning of several chapters. This should puted tomography (CT) and magnetic reso- assist understanding of the basic principles nance imaging (MRI). Despite recent major of the large number of available procedures technological strides, conventional radiol- for imaging a particular problem, in order ogy still has a crucial role to play in the that the correct investigation for each clini- assessment of a large number of patients cal situation can be chosen. Radiology is a and it is important, therefore, that the vast subject; the essentials are presented and basics of radiology be learnt to assist patient discussed in this book to provide a basic management. foundation course in radiology. For more Radiology has assumed a central role in detailed information the many excellent the initial diagnosis as well as subsequent textbooks available should be consulted. management of patients. The burden on the medical curriculum is continually PRP iv Chapter 1 Introduction Lecture Notes: Radiology, 3e. By Pradip R. Patel. Published 2010 by Blackwell Publishing Ltd. 1 Chapter 1 Introduction Introduction Recent technological advances have produced a bewildering array of complex imaging techniques and procedures. The basic principle of imaging, however, remains the anatomi- cal demonstration of a particular region and related abnormalities, the principal imaging modalities being: ● plain X - rays : utilizes a collimated X - ray beam to image the chest, abdomen, skeletal structures, etc.; ● fl uoroscopy: a continuous X- ray beam produces a moving image to monitor examina- tions such as barium meals, barium enemas, etc.; ● ultrasound (US): employs high - frequency sound waves to visualize structures in the abdomen, pelvis, neck and peripheral soft tissues; ● computed tomography (CT): obtains cross- sectional computerized densities and images from an X- ray beam/detector system; ● magnetic resonance imaging (MRI): exploits the magnetic properties of hydrogen atoms in the body to produce images; ● nuclear medicine (NM): acquires functional as well as anatomical detail by gamma radiation detection from injected radioisotopes. Contrast m edia Contrast agents are substances that assist visualization of some structures during the above techniques, working on the basic principle of X- ray absorption, thereby preventing their transmission through the patient. The most commonly used are barium sulphate to outline the gastrointestinal tract, and organic iodine preparations, the latter widely used intrave- nously in CT for vascular and organ enhancement. Contrast agents can also be introduced into specifi c sites, for example: ● arteriography : the arterial system; ● venography: the venous system; ● myelography : spinal theca; ● cholangiography : the biliary system; ● hysterosalpingography : uterus; ● arthrography : joints; ● sialography : salivary glands. The possibility of an allergic reaction exists with iodinated contrast media, an increased risk noted in those with a history of allergy, bronchospasm and cardiac disease, as well as in the elderly, neonates, diabetics or patients with multiple myeloma. ● Minor reactions: nausea, vomiting, urticarial rash, headache. ● Intermediate reactions: hypotension, bronchospasm. ● Major reactions: convulsions, pulmonary oedema, cardiac arrhythmias, cardiac arrest. Drug therapy should be readily available to treat reactions, for example: ● urticaria: chlorphenamine or other antihistamines; ● pulmonary oedema: furosemide i.v.; ● convulsions: diazepam i.v.; ● bronchospasm: hydrocortisone i.v. and bronchodilators such as salbutamol; ● anaphylactic reactions: adrenaline s.c. or i.v. 2 Introduction Chapter 1 Radiation p rotection All individuals receive natural background radiation but diagnostic tests now account for the largest source of exposure and every effort at reduction must be made. Although ion- izing radiation is deemed to be potentially hazardous, the risks should be weighed in the context of benefi ts to the patient. ● Doses should be kept to a minimum and a radiological investigation performed only if management is going to be affected. Consideration should be given to the radiation dose to the patient for each specifi c investigation. CT, barium and radionuclide studies are high - dose examinations whereas plain fi lms of the extremities and chest X - rays are typically low dose. ● The fetus is particularly sensitive, especially in the fi rst trimester with possible induction of carcinogenesis or fetal malformation. A menstrual history obtained in a woman of reproductive age, and if necessary a pregnancy test, will prevent accidental fetal exposure to radiation. ● Clear requests to the radiology department, with relevant clinical details, aids in the selection of the most appropriate views or investigations. ● Discussion of complex cases with a radiologist may help in choosing the most relevant study or examination. ● Unnecessary examinations should be avoided, for example repeat chest X - rays for resolu- tion of pneumonic consolidation at less than weekly intervals, or preoperative chest X - rays in young patients. ● Ultrasound and MRI, because of the lack of ionizing radiation, are the preferred imaging modalities where clinically indicated. 3 Chapter 1 Introduction X-ray tube X-ray beam Digital screen Image intensifier Digital processing Monitor for viewing continuous image (fluoroscopy) Figure 1.1 Basic principles of plain fi lms and fl uoroscopy. 4