Recent years have witnessed an astounding revolution in the field of imaging technology. At the heart of this revolution are major strides taken by the industry in all modalities including radiography, ultrasonography, digital subtraction angiography, computed tomography and magnetic resonance imaging. The imaging has moved from anatomic to functional, from static to real-time and from 2 dimensional to 3 or even 4 dimensional. All these major advancements in the information provided are expected at a faster rate and with lesser radiation dose. It is truly a tribute to science that several of these goals have actually been achieved. As radiologists, we have been privileged to be the chosen few to deliver these stunning images to the medical community. With this, however, comes greater responsibility. Our ability to create and interpret these amazing pictures requires us to comprehend the physics that goes into creating them. Also, the onus of minimizing the cost of imaging, selection of the optimal modality and minimizing radiation exposure finally rests on us.

This book has hence been planned as a volume attempting to summarize and deliver the advances in imaging technology relevant to the radiologist in a manageable capsule. We hope that it will serve as your friend and companion in understanding and negotiating the labyrinth of Imaging Physics. Compared to the First Edition published in 2000, the book has understandably been majorly restructured. We have attempted to cover all major aspects of technological advances relevant to a practicing radiologist, while keeping the book compact. It is our earnest hope that our readers will find this text informative and that it will aid in their learning process and daily practice.

We wish to thank all the contributors from the institutions, i.e. All India Institute of Medical Sciences, New Delhi, Maulana Azad Medical College, New Delhi and Postgraduate Institute of Medical Education and Research, Chandigarh, India, for their efforts in compiling this edition. We would also like to express our sincere appreciation to Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Managing Director), Mr Tarun Duneja (Director-Publishing), Mrs Samina Khan (PA to Director-Publishing), Mr KK Raman (Production Manager), Mr Sunil Kumar Dogra (Production Executive), Mr Neelambar Pant (Production Coordinator), Mr Subrata Adhikary (Commissioning Editor), Dr Mohd Naved (Senior Proofreader), Mr Girish Pandey (Typesetter), Mr Dinesh Joshi (Graphic Designer) and other staff of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, for their professionalism and dedication towards publication of this edition.

The amazing speed at which the field of radiology is mushrooming today would have surely astounded Roentgen, the “Father” of radiology. While physicians, a century ago, struggled with the nation of looking inside the living body without the cutting it open. At present, the physicians find it almost impossible to practice medicine without the help of sophisticated diagnostics imaging.

Cross-sectional imaging modalities have revolutionized the concept of imaging. Ultrasonography has advanced into wider areas of applications with increasing contrast use of color Doppler and Power Doppler techniques. The introduction of ultrasound contrast media and tissue harmonic imaging has further opened up new vistas in clinical applications of ultrasonography.

Since its introduction in 1971, computed tomography (CT) technology has come a long way. Modern scanners, capable of subsecond scanning, are ideal for the scanning chest and abdomen in a single breath-hold. Additional improvement includes more detectors to increase resolution and finer collimation allowing a reduction in slice thickness to minimize partial volume averaging. Introduction of spiral scanners has widened the scope of imaging by making 3D CT and 3D CT angiography possible.

Magnetic resonance imaging (MRI) was introduced into clinical medicine in 1981 and within a short time, it has assumed a role of unparalleled importance in diagnostic medicine. It is probably the most important imaging advancement since the introduction of X-rays in 1895. The resolution of 3D MR and 3D MR angiography has also advanced to the stage, where the replacement of conventional invasive angiography is now in sight. However, MR spectroscopy has failed to fill its early promise and still await routine clinical acceptance.

The role of the radiology is fast changing from that of a diagnostician usually supporting clinical diagnosis to that of a more active colleague tackling various clinical problems and performing a wide gamut of interventional procedures. The interventional radiologist of today is indeed going to be surgeon of the new millennium.

Functional neuroimaging with PET and SPET is emerging from the research stages and when more freely available, may have a major influence on clinical practice.

Teleradiology, which allows long distance transmission of images by extensive networking, has expanded the scope of diagnostic imaging well beyond our expectation.

The student of radiology needs constant guidance through this bewildering plethora of new information on imaging technology. A comprehensive understanding of technological advances in imaging and their clinical applications are necessary for practicing radiologists to be able to make an optimal choice of investigation in helping the referring physician to reach at a diagnosis.

Keeping this in mind, the faculty of radio-diagnosis at the All India Institute of Medical Sciences, Maulana Azad Medical College, New Delhi and Postgraduate Institute of Medical Education and Research, Chandigarh, India, present this seventh book in the series of Diagnostic Radiology, devoted to Advances in Imaging Technology, thus concluding the series of AIIMS, MAMC, PGI Imaging Courses.

fm10This book comprises of 16 chapters, covering the recent advances in ultrasonography, computed tomography, magnetic resonance imaging, nuclear medicine, digital radiography and interventional radiology. In addition, a full chapter has been devoted to the role of Internet in Radiology. Also, this book includes 7 more chapters on the subjects, which could not be covered in earlier volumes.

We hope, the reader shall find this book informative and valuable for better use of imaging technology.

We wish to take this opportunity to thank our faculty colleagues from AIIMS, MAMC and PGIMER for their active support and cooperation. We also express our sincere thanks to Shri Jitendar P Vij (Group Chairman) and other staff of M/s Jaypee Brothers Medical Publishers (P) Ltd., New Delhi, India, for timely publication of all previous books including the present one.