Grainger & Allison's Diagnostic Radiology, 5th Edition

1835 Pages·2007·129.18 MB·English

Contributors
† : deceased
Andy AdamMBBS (Hons), FRCP, FRCS, Clive I. BartramFRCS, FRCP, FRCR Gisele Brasil Caseiras PhD
FRCR, FFRRCSI (Hon) Emeritus Consultant, St Mark’s Hospital Research Fellow
Professor of Interventional Radiology and Honorary Professor of Insitute of Neurology
Department of Radiology Gastrointestinal Radiology University College London
St Thomas’ Hospital Faculty of Medicine London, UK
King’s College London Imperial College
London, UK London, UK Jackie E. Brown BDS, MSc, FDSRCP, DDRRCR
Consultant Oral and Maxillofacial
E. Jane Adam MBBS, MRCP, FRCR Philip P. W. BearcroftFRCP, FRCR Radiologist
Consultant Radiologist Consultant Radiologist Kings College London Dental Institute
Department of Radiology Department of Radiology Guy’s Dental Hospital
St George’s Hospital Cambridge University Hospitals NHS London, UK
London, UK Foundation Trust
Addenbrooke’s Hospital Dina F. CarolineMD, PhD
Judith E. Adams MBBS, FRCR, FRCP Cambridge, UK Professor Emerita
Chair, Diagnostic Radiology Department of Radiology
Imaging Science and Biomedical Anna-Maria BelliDMRD, FRCR Temple University Hospital
Engineering Consultant Vascular Radiologist and Philadelphia
University of Manchester Reader in Radiology Pennsylvania, USA
Honorary Consultant Radiologist Department of Radiology
Royal Infirmary St George’s Hospital Silvia D. ChangMD, FRCP(C)
Manchester, UK London, UK Assistant Professor
University of British Columbia
David J. Allison BSc, MD, MRCS, LRCP, MBBS, Anthony R. BerendtBM, BCh, FRCP Department of Radiology
DMRD, FRCR, FRCP Consultant Physician-in-Charge Vancouver General Hospital
Emeritus Professor of Imaging Bone Infection Unit Vancouver, Canada
Imperial College Nuffield Orthopaedic Centre
London, UK Oxford, UK W. K. ‘Kling’ ChongBMedSci, MD, MRCP, FRCR
Consultant Neuroradiologist
Sandra Allison MD Lol BermanFRCP, FRCR Department of Radiology
Assistant Professor of Radiology University Department of Radiology Great Ormond Street Hospital for
Director, Radiology Residency Program Addenbrooke’s Hospital Children NHS Trust
Director, Ultrasound Cambridge, UK London, UK
Georgetown University Hospital
Washington DC, USA Martin J. K. Blomley† Bairbre ConnollyMBBCh, BAO, FRCSI, MCH,
FFRRCSI, FRCP(C)
Philip AnslowFRCR Carol A. BolesMD Medical Director and Division Head of
Consultant Neuroradiologist Associate Professor of Radiology Image Guided Therapy
Department of Radiology Associate, Surgical Sciences Pediatric Interventional Radiologist
Radcliffe Infirmary Orthopedic Surgery Assistant Professor, University of Toronto
Oxford, UK Wake Forest University Department of Diagnostic Imaging
North Carolina, USA The Hospital for Sick Children
Susan M. AscherMD
Toronto, Canada
Georgetown University Medical Center Jamshed B. BomanjiMBBS, MSc, PhD
Washington DC, USA Consultant in Nuclear Medicine Susan J. CopleyMBBS, MD, MRCP, FRCR
UCLH Trust Consultant Radiologist and Honorary
Zelena A. AzizMD, MRCP, FRCR Middlesex Hospital Senior Lecturer
Consultant Radiologist London, UK Radiology Department
Department of Radiology
Hammersmith Hospital
London Chest Hospital
London, UK
London, UK
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x CONTRIBUTORS
David O. CosgroveMA, MSc, FRCP, FRCR Robert J. EckersleyPhD Philip C. GoodmanMD
Emeritus Professor Research Associate Professor of Radiology
Imaging Sciences Department Imaging Sciences Department Chief, Thoracic Imaging Division
Faculty of Medicine Faculty of Medicine Department of Radiology
Imperial College Imperial College Duke University Medical Center
Hammersmith Hospital Hammersmith Hospital Durham
London, UK London, UK North Carolina, USA
Nigel CowanPGDipLATHE, FRCP Andrew J. EvansMRCP, FRCR Isky GordonFRCR, FRCP
Oxford, UK Consultant Radiologist Professor of Paediatric Imaging
Nottingham Breast Institute Institute of Child Health
Justin J. CrossMRCP, FRCR Nottingham City Hospital London, UK
Consultant Neuroradiologist Nottingham, UK
Department of Radiology Nicholas GourtsoyiannisFRCR (Hon)
Addenbrooke’s Hospital Jane EvansonBSc, MBBS, MRCP, FRCR Professor of Radiology
Cambridge, UK Consultant Neuroradiologist, Barts & The University of Crete
London Hospital NHS Trust Faculty of Medicine
Paras DalalBSc, MRCP, FRCR The Royal London Hospital Heraklion, Crete
Research Fellow in Thoracic Imaging London, UK Greece
Department of Radiology
Royal Brompton Hospital Laura FenderBMedSci, BMBS, MRCP, FRCR Andrew J. GraingerBM, BS, MRCP, FRCR
London, UK Consultant Radiologist Consultant Radiologist
Nottingham University Hospital Chapel Allerton Orthopaedic Centre
Maria DaskalogiannakiMD Nottingham, UK Leeds Teaching Hospitals
Registrar in Radiology Leeds, UK
Department of Radiology Alan H. FreemanMBBS, FRCR
University Hospital of Heraklion Consultant Radiologist Ronald G. GraingerMB ChB(Hons), MD, FRCP,
Crete, Greece Department of Radiology DMRD, FRCR, FACR(Hon), FRACR(Hon)
Addenbrooke’s Hospital Professor of Diagnostic Radiology
A. Mark DaviesFRCR Cambridge, UK (Emeritus)
Consultant Radiologist University of Sheffield
Royal Orthopaedic Hospital Julia GatesMD Honorary Consultant Radiologist
Birmingham, UK Assistant Professor of Radiology Royal Hallamshire Hospital and Northern
Department of Radiology General Hospital
Adrian K. DixonMD, FRCR, FRCP, FRCS, Tufts University School of Medicine Sheffield, UK
FMedSci, FFRRCSI (Hon), FRANZCR (Hon) Springfield
Professor of Radiology Massachusetts, USA Philippe GrenierFRCR (Hon)
Department of Radiology Professor of Radiology
Addenbrooke’s Hospital Robert N. GibsonMBBS, MD, FRANZCR, DDU Service de Radiologie Polyvalente
University of Cambridge Professor of Radiology Diagnostique et Interventionnelle
Cambridge, UK Department of Radiology Hôpital Pitié-Salpêtrière
University of Melbourne Paris, France
Rose de BruynDMRD, FRCR Royal Melbourne Hospital
Consultant Radiologist Victoria, Australia Roxana S. GunnyBS, BSc, MRCP, FRCR
Department of Radiology Consulant Neuroradiologist
Great Ormond Street Hospital for Sick Raymond J. GodwinMA, MB, Bchir, FRCP, FRCR Department of Radiology
Children NHS Trust Consultant Radiologist Great Ormond Street Hospital for
London, UK Department of Radiology Children NHS Trust
West Suffolk Hospital London, UK
Claudio DefilippiMD Suffolk, UK
Consultant Radiologist Christine M. HallMBBS, DMRD, FRCR MD
Department of Radiology Karen GoldstoneBSc, MSc, Csci, FIPEM Professor of Paediatric Radiology
OIRM - S. Anna Hospital Radiation Protection Advisor Great Ormond Street Hospital for
Turin, Italy Acting Head of Department of Medical Children NHS Trust
Physics and Clinical Engineering London, UK
Sujal R. Desai MD, MRCP, FRCR East Anglian Regional Radiation
Consultant Radiologist Protection Service (EARRPS) David M. HansellMD, FRCP, FRCR, LRSM
Department of Radiology Addenbrooke’s Hospital Professor of Thoracic Imaging
King’s College Hospital Cambridge, UK Department of Radiology
London, UK Royal Brompton Hospital
London, UK
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CONTRIBUTORS xi
George G. Hartnell FRCR, FRCP Adrian K. P. LimMD, FRCR Stuart E. Mirvis MD, FACR
Director of Cardiovascular and Interven- Consultant Radiologist and Professor of Radiology
tional Radiology Senior Lecturer Department of Radiology
Department of Radiology Imaging Sciences Department University of
Baystate Medical Center Faculty of Medicine Imperial College Maryland School of Medicine
Springfield Hammersmith Hospital Baltimore
Professor of Radiology London, UK Maryland, USA
Tufts University Medical School
Boston David J. LomasMA, MB, BChir, FRCR, FRCP Sameh K. Morcos FRCS, FFRRCSI, FRCR
Massachusetts, USA Professor of Clinical Magnetic Resonance Professor of Diagnostic Imaging
Imaging University of Sheffield
Hedvig Hricak MD, Dr. Med, SC, Dr. h.c, FRCR (Hon) Department of Radiology Consultant Radiologist
Chairman, Department of Radiology Addenbrooke’s Hospital Department of Diagnostic Imaging
Carroll and Milton Petrie Chair Cambridge, UK Northern General Hospital
Professor of Radiology, Weill Medical Sheffield, UK
College of Cornell University Sharyn L. S. MacDonaldMBChB, FRANZCR
Memorial Sloan-Kettering Cancer Center Consultant Radiologist Robert A. MorganMBChB, MRCP, FRCR
New York, USA Department of Radiology Consultant Radiologist
Christchurch Hospital Department of Radiology
James E. JacksonMRCP, FRCR Christchurch, New Zealand St George’s Hospital
Consultant Radiologist London, UK
Department of Imaging David MacVicarMA, MRCP, FRCP, FRCR
Hammersmith Hospital Consultant Radiologist Iain MorrisonMBBS, MRCP, FRCR
London, UK Department of Diagnostic Radiology Consultant Radiologist
Royal Marsden Hospital Radiology Department
H. Rolf JägerFRCR, MD Sutton, UK Kent and Canterbury Hospital
Reader in Neuroradiology Canterbury, UK
Institute of Neurology Adrian ManhireBSc, MBBS, FRCP, FRCR
University College London Consultant Radiologist Nestor L. MüllerMD, PhD, FRCPC
Honorary Consultant Neuroradiologist Nottingham City Hospital Professor and Chairman
The National Hospital for Neurology Nottingham, UK Department of Radiology
and Neurosurgery and University College University of British Columbia
Hospital Tarik F. MassoudMA, MD, PhD, FRCR Head and Medical Director
London, UK University Lecturer and Honorary Department of Radiology
Consultant in Neuroradiology Vancouver General Hospital
Jonathan J. JamesBMBS, FRCR University Department of Radiology Vancouver, Canada
University of Cambridge School of
Consultant Radiologist
Clinical Medicine Graham MunnekeMRCP, FRCR
Nottingham Breast Institute
Nottingham City Hospital Addenbrooke’s Hospital Consultant in Interventional Radiology
Nottingham, UK Cambridge, UK Department of Radiology
St. George’s Hospital
Renee M. KendzierskiDO Kieran McHughFRCPI, DCH, FRCR London, UK
Assistant Professor of Radiology Department of Radiology
Department of Radiology Great Ormond Street Hospital for Sick Alison D. MurrayMB ChB (Hons), FRCR, FRCP
Temple University Hospital Children NHS Trust Senior Lecturer in Radiology
Philadelphia London, UK Department of Radiology
Pennsylvania, USA University of Aberdeen
James MeaneyFRCR, FFRRCSI Aberdeen, UK
Dow-Mu KohMRCP, FRCP Director of MRI
St James’s Hospital Richard A. NakielnyFRCR
Senior Lecturer and Honorary Consultant
Department of Radiology Dublin, Ireland Honorary Clinical Lecturer
Royal Marsden Hospital Directorate of Medical Imaging &
Sutton, UK Hylton B. MeireFRCR, DRCOG, DMRD Medical Physics
Consultant Radiologist (Retired) Royal Hallamshire Hospital
Isla LangMBChB, MRCP, FRCR King’s College Hospital Sheffield, UK
London, UK
Consultant Paediatric Radiologist
Hrudaya NathMD
Sheffield Children’s Hospital
Sheffield, UK Kenneth A. Miles MD, FRCR, MSc, FRCP Professor of Radiology
Clinical Imaging Sciences Centre Department of Radiology
Brighton and Sussex Medical School University of Alabama Hospitals
University of Sussex Birmingham
Falmar, Brighton, UK Alabama, USA
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xii CONTRIBUTORS
Tony NicholsonMSc, FRCR Sheila RankinFRCR John RoutBDS, FDSRCS, MDentSc, DDRRCR, FRCR
Consultant Vascular Radiologist Consultant Radiologist Consultant Oral and Maxillofacial
Department of Clinical Radiology Department of Radiology Radiologist
Leeds Teaching Hospitals Guy’s and St. Thomas’ Foundation Trust Birmingham Dental Hospital
Leeds, UK London, UK Birmingham, UK
Amaka C. OffiahBSc, MBBS, MRCP, FRCR, PhD Padma RaoMBBS, BSc, MRCP, FRCR, Michael B. RubensMB, DMRD, FRCR
Consultant Radiologist (Academic) FRANZCR Consultant Radiologist
Great Ormond Street Hospital for Consultant Paediatric Radiologist Department of Radiology
Children NHS Trust Royal Children’s Hospital Royal Brompton Hospital
London, UK Parkville London, UK
Melbourne
Simon PadleyBSc, MBBS, FRCP, FRCR Victoria, Australia Asif SaifuddinBSc (Hons), MBChB, MRCP, FRCR
Consultant Radiologist Consultant Radiologist
Department of Radiology Christine ReekBSc, FRCR Department of Radiology
Chelsea and Westminster Hospital Consultant Radiologist Royal National Orthopaedic Hospital
London, UK Department of Radiology NHS Trust
Greenfield Hospital Stanmore, UK
Martyn N. J. PaleyPhD, FInstP Leicester, UK
Professor of MR Physics Evis Sala MD, PhD, FRCR
Academic Radiology John H. ReynoldsDMRD, FRCR, MMedSci University Lecturer in Oncology Imaging
University of Sheffield Consultant Radiologist University Department of Radiology
Sheffield, UK Birmingham Heartlands Hospital Addenbrooke’s Hospital
Birmingham, UK Cambridge, UK
Nickolas PapanikolaouPhD
Biomedical Engineer Rodney H. ReznekFRANZCR (Hon), FRCP, FRCR Caron Sandhu FRCR
Department of Radiology Professor of Diagnostic Imaging Consultant Radiologist
University Hospital of Heraklion The Centre for Cancer Imaging Department of Radiology
Crete, Greece St Bartholomew’s Hospital and The Guy’s and St. Thomas’ Hospital
London Queen Mary’s School of London, UK
Jai PatelMBChB, MRCP, FRCR Medicine and Dentistry
Consultant Vascular Radiologist London, UK Dawn SaundersMD, MRCP, FRCR
Department of Clinical Radiology Consultant Neuroradiologist
St James’s University Hospital Philip M. RichBSc, FRCS, FRCR Department of Radiology
Leeds, UK Consultant Neuroradiologist Great Ormond Street Hospital for
Department of Neuroradiology Children NHS Trust
Anne PatersonMBBS, MRCP, FRCR, FFR RCSI Atkinson Morley Wing London, UK
Consultant Paediatric Radiologist St George’s Hospital
Radiology Department London, UK Daniel J. ScoffingsMRCP, FRCR
Royal Belfast Hospital for Sick Children Specialist Registrar in Neuroradiology
Belfast, UK Andrea Rockall MD, BS, BSc, MRCP, FRCP Addenbrooke’s Hospital
Department of Radiology Cambridge, UK
Praveen PedduMRCS, FRCR St Bartholomew’s Hospital
Specialist Registrar in Radiology London, UK Djilda SegermanMA, MSc, MIPEM
Department of Radiology Head of Nuclear Medicine Physics
King’s College Hospital Giles Roditi FRCP, FRCR Department of Medical Physics
London, UK Consultant Radiologist Brighton and Sussex University Hospitals
Department of Radiology NHS Trust
A. Michael PetersBSc, MD, MSc, MRCP, Glasgow Royal Infirmary Brighton, UK
MRCPath, FRCR Glasgow, UK
Professor of Nuclear Medicine Kathirkama ShanmuganathanMD
Brighton and Sussex Medical School Lee F. RogersMD Associate Professor of Radiology
University of Sussex Clinical Professor of Radiology Department of Radiology
Brighton, UK Department of Radiology University of Maryland School of
University of Arizona Health Services Medicine
William H. Ramsden BM, FRCR Tucson Baltimore
Consultant Paediatric Radiologist Arizona, USA Maryland, USA
Department of Clinical Radiology
St James’s University Hospital Giles Rottenberg FRCR Ashley S. ShawMRCP, FRCR
Leeds, UK Consultant Radiologist Consultant Radiologist
Department of Radiology Department of Radiology
Guy’s and St. Thomas’ Foundation Trust Addenbrooke’s Hospital
London, UK Cambridge, UK
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CONTRIBUTORS xiii
Satinder P. SinghMD, FCCP Mihra S. TaljanovicMD, MA Sarah J. VinnicombeBSc, MRCP, FRCR
Associate Professor of Radiology Associate Professor of Clinical Radiology Consultant Radiologist
Director Cardiac CT and Clinical Orthopedic Surgery Department of Radiology
Director, Combined Cardiopulmonary Head - Musculoskeletal Imaging Section St Bartholomew’s Hospital
and Abdominal Fellowship Department of Radiology London, UK
Chief of Cardiopulmonary Radiology Tucson
Department of Radiology Arizona, USA Gustav K. von SchulthessMD, PhD
University of Alabama Hospitals Professor and Director
Birmingham Andrew M. TaylorBA (Hons), BM BCh, MRCP Department of Radiology
Alabama, USA FRCR University Hospital
Consultant Radiologist Zurich, Switzerland
S. Aslam A. SohaibMRCP, FRCR Department of Clinical Radiology
Radiology Department Great Ormond Street Hospital for Iain D. WilkinsonBSc, MSc, PhD, CSci,
Royal Marsden Hospital Children NHS Trust ARCP, FIPEM
London, UK London, UK Reader in Magnetic Resonance
& Consultant Clinical Scientist
Alan SpriggMBChB, DCH, DRCOG, DMRD, FRCR, Stuart TaylorBSc, MD, MRCP, FRCR Academic Radiology
FRCPCH Consultant Radiologist University of Sheffield and
Consultant Paediatric Radiologist Department of Intestinal Imaging Sheffield Teaching Hospitals
Sheffield Children’s Hospital St Marks Hospital NHS Foundation Trust
Sheffield, UK Northwick Park Sheffield, UK
Harrow, UK
John M. StevensMBBS, DRACR, FRCR A. Robin M. Wilson FRCR, FRCP(E)
Lyshom Department of Neuroradiology Henrik S. ThomsenMD Consultant Radiologist
Radiology Department Professor and Chairman King’s College Hospital and
The National Hospital for Neurology and Department of Diagnostic Radiology Guy’s and St Thomas’ Foundation Trusts
Neurosurgery Copenhagen University Hospital London, UK
London, UK Herlev, Denmark
David J. WilsonMBBS, BSc, FRCP, FRCR
Dennis J. StokerMB, FRCP, FRCS, FRCR Paolo TomaMD Consultant Musculoskeletal Radiologist
Emeritus Consultant Radiologist Radiologist-in-Chief Nuffield Orthopaedic Centre and
Henley-on-Thames, UK Radiology Department University of Oxford
G. Gaslini Institute Oxford, UK
Nicola H. StricklandBM BCh, MA (Hons), Genoa, Italy
(Oxon), FRCP, FRCR Stuart J. YatesMSci, MSc, CSci, MIPEM
Consultant Radiologist Peter TwiningFRCR, BSc, BS MB Principal Physicist
Imaging Department Consultant Radiologist Department of Medical Physics & Clinical
Hammersmith Hospitals NHS Trust Nottingham University Hospital Engineering
Honorary Senior Lecturer Nottingham, UK Cambridge University Hospitals NHS
Imperial College Foundation Trust
London, UK John A. VerschakelenMD, PhD Cambridge, UK
Professor of Chest Radiology
Louise E. SweeneyMBBCH, BAO, DCH, DMRD, Department of Radiology
FRCR, FFR, RCSI University Hospitals Gasthuisberg
Consultant Paediatric Radiologist Leuven, Belgium
Radiology Department
Royal Belfast Hospital for Sick Children
Belfast, UK
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Preface
We hope that this 5th edition of Diagnostic Radiology will year basic course followed by two years of training in selected
continue to build on the original vision of Professors Grainger subspecialties, the factual examination in the UK has moved to
and Allison who, back in the early 1980s, saw the need for an earlier stage in training with less emphasis on some of the
a ‘bible’ for doctors studying for postgraduate examinations diagnostic rarities so beloved by examiners of old. The cur-
in radiology, and to provide a bench book for reporting riculum is now somewhat less comprehensive and the reduc-
and reference. The success of the first four editions, which tion in size of this 5th Edition reflects that – down from three
were extremely well received by an increasingly interna- volumes to two. In this electronic age there are many data-
tional readership, speaks for the realisation of their dream. bases of images available on the internet, with accompanying
Few could have predicted at that stage the extraordinary text. Nevertheless, we believe that well structured textbooks
growth of radiology, or its increasing importance within all remain an essential part of medical education and practice as
aspects of modern medicine. The unprecedented expansion in they present information in a format that facilitates learning,
the imaging repertoire, together with the trend for increasing guiding the reader through an unfamiliar field. We are con-
subspecialisation, have led to changes in training and in the vinced that Diagnostic Radiology will remain a valuable resource
methods used for teaching and learning. This book has had for many years to come.
to evolve to reflect these changes, adapting to the perceived We are again extremely grateful to the distinguished inter-
needs of those facing postgraduate examinations and also to national cast of authors who have all worked hard to deliver
all radiologists who wish to have an up-to-date basic general fresh and up-to-date material. We are also most grateful to
textbook for ready reference and illustration. Michael Houston, Gavin Smith and Nora Naughton for their
An attempt to cover every subject in detail would have professional skills and publishing expertise and to Jeremy
resulted in a huge book that would have been very difficult to Rabouhans for invaluable help with proof reading. We could
use. We have chosen to concentrate on those subjects that most never have done it without them!
radiologists need to know well, and to pay special attention to
the needs of trainee radiologists preparing for examinations. Andy Adam
Because training throughout Europe is moving towards a three Adrian Dixon
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Acknowledgements
This edition could not have occured without the large amount leagues remained remarkably cheerful throughout and kept
of work done by all the contributing authors and their col- strong heads even when chapters were late, images missing,
leagues. However, the vision and overall planning of Michael and all the other hiccups that can hinder progress in a project
Houston at Elsevier have been fundamental in bringing the of this kind. At a local level, all the Editors would like to thank
book to fruition. So, too, has the meticulous gathering and their various secretaries, technicians and colleagues who have
editing of material by Gavin Smith. Finally, the skilful copy- helped proofread, collect material and made various other
editing, and other tasks provided by Nora Naughton, and invaluable contributions.
her remarkable team, must not be forgotten; without them
the Editors simply could not have managed. All of these col- The Editors
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1
CHAPTER
Picture Archiving and
Communication Systems
(PACS) and Digital
Radiology
Nicola H. Strickland
T he role of PACS Compression
Advantages and disadvantages of PACS • Lossless
• Advantages of PACS • Lossy
• Disadvantages of PACS • Need for compression
Planning for PACS Digitization policy
• The PACS project team Teleradiology
• Tendering for a PACS • Review of images from home
• The PACS contract • Teleradiology linkage between two or more hospitals for joint
• Economic considerations MDTMs
• Purchasing versus leasing a PACS • Outsourcing of imaging examinations for reporting
• PRE-PACS workflow and preparation • Tele-education
• Acronyms: DICOM, HL7 and IHE Security
PACS project implementation • User-specific log-in and password
• Implementation of digital image acquisition prior to PACS • Monitor screen savers
• Integration of PACS • Workstation time-outs
‘Value-added’ PACS • Encryption
Modern PACS architecture • Audit trails
• PACS networks • Firewalls
• Storage requirements and solutions for PACS • Teleradiology security
PACS workstations PACS training
• Monitor quality on PACS workstations Quality assurance
Conference room design • Plain radiography
Graphic user interface • PACS workstations
• Soft-copy tools PACS housekeeping
Software concepts • Storage commitment
• Prefetching • Modality performed procedure step
Current and future directions of PACS
THE ROLE OF PACS
A picture archiving and communication system (PACS) aims to conjunction with the clinical details of the patient and the
replace conventional analogue film and paper clinical request associated radiological report displayed in electronic format.
forms and reports with a completely computerized electronic Clearly PACS must replace the functions of traditional X-ray
network whereby digital images are viewed on monitors in film; i.e. image acquisition, storage, transportation and display.
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4 SECTION 1 • IMAGING TECHNIQUES AND GENERAL ISSUES
Were these the only roles of a PACS, it would be an extremely ing upon a potential time scale in which the hospital-wide
complex and expensive means of replacing traditional film. A PACS is to be achieved, and deciding upon a scaleable PACS
PACS must improve upon a film-based system, preferably in architecture. Ideally the whole hospital infrastructure should
a cost-neutral manner. The major added value of a PACS is be adapted at the outset so that a hospital-wide PACS can
efficiency of data management. be accommodated at a later stage. This includes providing
True efficiency benefits can only be realized once a PACS an uninterruptable power supply (UPS), allowing sufficient
is at least hospital-wide, since any more limited installation cabling space in floors and ceilings, and adapting the air con-
means running two systems in parallel, i.e. it entails continu- ditioning system for PACS. The hospital information tech-
ing to produce conventional film and moving it around the nology (IT) network is likely to need upgrading to enable
hospital, as well as the cost of installing and maintaining a large amounts of image data to be transported, and it is advis-
PACS. Thus, even if funds are limited initially, it is advisable able to install multiple PACS ‘drops’ (workstation outlets) so
at least to aim and plan for growing the PACS installation that more PACS workstations can easily be added at a later
into a hospital-wide system ultimately. This means decid- date.
ADVANTAGES AND DISADVANTAGES OF PACS
Although the concept of PACS has now been in existence for imaging study, remain in their correct orientation, and are
over 20 years, advances in computer hardware technology only automatically chronologically ordered. Database searches
enabled it to become a realistic clinical entity in the 1990s. for a particular patient or study are rapidly effected. Com-
PACS installations are now rising exponentially worldwide, puterized data can easily be duplicated, i.e. ‘backed up’ as a
and although most institutions with PACS have achieved a precaution against loss, and cheaply stored in a distant loca-
completely filmless working environment, few function in a tion if desired for disaster recovery purposes.
paperless mode. PACS has proved itself over the last 10 years • Viewing of images on monitors allows numerous post-
in the clinical environment, however, and it would now be processing soft-copy manipulations: a range of different
unthinkable not to implement PACS when installing a new window width and level settings can be applied to CT
imaging department, or a new hospital. images, for example, within a fraction of a second, whereas
previously further sheets of film had to be printed with the
ADVANTAGES OF PACS appropriate settings for soft tissue, lung or bone as desired3,4.
• There are some direct cost savings due to PACS: there is no
There are a number of powerful advantages accruing from a longer a film budget, film packet cost or chemical process-
hospital-wide PACS: ing. (The ability to print film need not be retained pro-
• Once correctly acquired onto the PACS, no image can ever vided a CD burner is linked to the PACS to burn imaging
be lost or misfiled and is always available when needed. This studies for transfer of patients outside the institution, or in
is a major benefit considering that in many hospitals up to the event of a PACS failure or planned downtime). Ancillary
20 per cent of conventional films are missing at the time staff – filing clerks and darkroom technicians – are no l onger
they are clinically required. In addition to the convenience needed.
of always having the appropriate image available when it • The most frequently cited benefit of PACS by nonradiolog-
is wanted for viewing, no patient is re-irradiated simply ical clinicians is the very substantial time saving incurred by
because a previous key study has been lost. their never having to search for or retrieve films. This time
• PACS facilitates the easy comparison of a patient’s current saving represents a considerable indirect financial benefit of
and historical examinations, and of examinations performed a hospital-wide PACS, and should certainly be costed when
on the same body part using different imaging techniques, a business case for PACS is being made.
which is desirable in the interests of optimum clinical • After a hospital-wide PACS has been installed, old films
practice, and always possible since none of the relevant can progressively be removed from the film filing room
comparative images is missing1. (film store) starting with the oldest first. The timing of this
• All images remain accessible from the PACS archives day manoeuvre will depend upon local and national policy,
and night, every day of the year. but it has been shown5 that most radiological compari-
• Simultaneous multilocation viewing of the same image sons are made with studies obtained during the preced-
is possible on any workstation connected to the PACS ing 6 months, although this may be longer in institutions
network, whereas hard-copy film can manifestly only be in with a large oncological or paediatric practice. Mainte-
one place at any one time. nance of a film store, with its associated lighting, heating
• Image retrieval is infinitely quicker from PACS than it is and cleaning, and the value of the physical space itself,
using conventional film where someone physically has to is particularly costly in hospitals located in cities where
go and fetch the film packet2. the space is at a premium. Even off-site film storage at
• The benefits of a computerized system mean that all images a cheaper location is worth introducing as a cost-saving
correctly and permanently reside under the appropriate measure in such institutions in the early years after PACS
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