1. Anne BrightPlanning and positioning inMRI

2. Planning and Positioning in MRI 3. Planning and Positioning in MRI Anne Bright 4. 5. ContentsAbbreviations .......................................................................... viiAcknowledgements . .....................................................................viiiAuthor . ................................................................................ ixDedication .............................................................................. ixReviewers .............................................................................. ixIntroduction............................................................................ xSection 1 Head and neckCranial .nerves ........................................................................... 2Chapter .1 .1 . Brain .................................................................... 5Chapter .1 .2 . Pituitary ................................................................ 10Chapter .1 .3 . Orbits .(CN .II) ............................................................ 15Chapter .1 .4 . Trigeminal .nerve .(CN .V)................................................... 19Chapter .1 .5 . Cerebellopontine .angles .(CN .VIIVIII) ........................................ 24Chapter .1 .6 . Posterior .fossa .(CN .IXXII) ................................................. 30Chapter .1 .7 . Temporal .lobes ........................................................... 34Chapter .1 .8 . Nasopharynx .and .sinuses.................................................. 38Chapter .1 .9 . Temporomandibular .joints .................................................. 43Chapter .1 .10 .Soft .tissue .neck .......................................................... 47Chapter .1 .11 .Brachial .plexus ........................................................... 52Chapter .1 .12 .Head .and .neck .vascular .imaging . ............................................ 57Further .reading ......................................................................... 63Section 2 SpineChapter .2 .1 . Cervical .spine ............................................................ 67Chapter .2 .2 . Thoracic .spine........................................................... 74Chapter .2 .3 . Lumbar .spine ............................................................ 80Chapter .2 .4 . Sacrum .and .coccyx....................................................... 86Chapter .2 .5 . Full .spine............................................................... 90Further .reading ......................................................................... 97Section 3 Chest and abdomenChapter .3 .1 . Mediastinum . ............................................................ 99Chapter .3 .2 . Heart . ................................................................. 104Chapter .3 .3 . Breast ................................................................. 112Chapter .3 .4 . Liver .and .gall .bladder.................................................... 117Chapter .3 .5 . Adrenals .and .kidneys.................................................... 124Planning and Positioning in MRI Contentsv 6. Chapter .3 .6 . Pancreas ............................................................... 129 Chapter .3 .7 . Aorta . ................................................................. 134 Further .reading ........................................................................ 139 Section 4 Pelvis Chapter .4 .1 . Rectum .and .anus ........................................................ 142 Chapter .4 .2 . Female .pelvis ........................................................... 150 Chapter .4 .3 . Male .pelvis ............................................................. 156 Chapter .4 .4 . Testes................................................................. 161 Chapter .4 .5 . Fetal .brain............................................................. 166 Chapter .4 .6 . Pelvic .arteries . .......................................................... 171 Further .reading ........................................................................ 173 Section 5 Upper limb Chapter .5 .1 . Shoulder ............................................................... 175 Chapter .5 .2 . Elbow ................................................................. 184 Chapter .5 .3 . Wrist .................................................................. 190 Chapter .5 .4 . Thumb .and .fingers ....................................................... 195 Chapter .5 .5 . Humerus .and .forearm.................................................... 201 Further .reading ........................................................................ 206 Section 6 Lower limb Chapter .6 .1 . Hipunilateral . ......................................................... 208 Chapter .6 .2 . Quadriceps .and .hamstring ................................................. 216 Chapter .6 .3 . Knee .................................................................. 222 Chapter .6 .4 . Ankle................................................................. 228 Chapter .6 .5 . Midfoot . ............................................................... 234 Chapter .6 .6 . Forefoot .and .toes ........................................................ 239 Further .reading ........................................................................ 243 Index ................................................................................ 244vi Contents Planning and Positioning in MRI 7. AbbreviationsABER armabductedandexternallyrotated LVLAleftventricleandleftatriumACCadrenocorticalcarcinomaLVOTleftventricularoutflowtractACLanteriorcruciateligamentMCL medialcollateralligamentACTH adrenocorticotropichormone MFH malignantfibroushistiocytomaADIR armabductedandinternallyrotated MIP maximumintensityprojectionALPSAanteriorlabroligamentousperiosteal MRmagneticresonancesleeveavulsion MRA magneticresonanceangiographyASIS anteriorsuperioriliacspine MRCPmagneticresonanceATTanteriortibialtendon cholangiopancreatographyAVMarteriovenousmalformationMRI magneticresonanceimagingBPHbenignprostatichyperplasiaMSmultiplesclerosisCBDcommonbileductNOF neckoffemurCLPM condylelateral-pterygoidmuscleNPC nasopharyngealcarcinomaCN cranialnervesOAosteoarthritisCPAcerebellopontineangles PCC pheochromocytomaCSFcerebrospinalfluid PCL posteriorcruciateligamentCT computerisedtomography PFD pelvicfloordysfunctionCTNorSTN classicorstructuraltrigeminal PTT posteriortibialtendonneuralgia PVNSpigmentedvillonodularsynovitisDRUJ distalradio-ulnarjointRArheumatoidarthritisECGelectrocardiogramor RARErapidacquisitionandrelaxationelectrocardiograph enhancementERCP endoscopicretrogradeRCC renalcellcarcinomacholangiopancreatograhpyREZ rootexitzoneFABS flexionandabductioninsupination RFradiofreqencyFAIfemoro-acetabularimpingement RVOTrightventricularoutflowtractFDLflexordigitorumlongus SCC squamouscellcarcinomaFHLflexorhallucislongusSLscapholunateFNHfollicularnodularhyperplasiaSLAPsuperiorlabralanteriorposteriorGBMglioblastomamultiforme SNHLsensorineuralhearinglossGREgradientecho SOC synovialosteochondromatosisHAGL humeralavulsionglenoidligament SOL spaceoccupyinglesionHCChepatocellularcarcinomaSSFPsingleshotfastspinechoIACinternalauditorycanal SSNHL suddensensorineuralhearinglossIV intravenous SST supraspinatoustendonIVCinferiorvenacavaTFCCtriangularfibrocartilagecomplexLCLlateralcollateralligamentinjuryLPMlateralpterygoidmuscleTMJ temporomandibularjointPlanning and Positioning in MRI Abbreviations vii 8. Acknowledgements A team of people, both personal and professional,details in cardiac imaging. Thanks also to Paul has supported me. Without them this tome may not Dobie from Radar Imaging in Melbourne. have been realised.The MRI radiographers at North Shore Radiology First Luisa Cecotti, who so graciously threw me offhave tolerated my quizzing and assisted in the the cliff when I was too timid to crawl to the edge. search for the images that have formed the basis of Without your push, I would probably still be rumi- this text. Thanks Matt Hammond. Lets get those nating about the possibilities.hamstrings to London for 2012! Sunalie Silva, Melinda McEvoy, Samantha McCul- Thanks to all the vendor representatives who loch, Rebecca Cornell, Natalie Hamad and Helenaassisted with approval of images of the coils shown, Klijn at Elsevier and Brenda Hamilton. You keptin particular Imbi Semenov, Anne Davidson and reassuring me of the efficacy of this project, believ- Barbara Pirgousis (GE Healthcare); David Kent, ing in what I often doubted. Thank you.Derby Chang, Kathleen Dunst and Timothy Hands(Imaxeon/Medrad); Peter Pasfield (Philips); Wells- My employers at North Shore Radiology have beenley Were, May Teo and Jo Ellerton (Siemens). wildly enthusiastic about my efforts to write this book. Especial thanks must go to Dr James Christie,In everything we do, family should come first. For who provided unfettered access and support for the me, the effort that has gone into producing this collection of images and access to literature. In con- work would be meaningless if those I hold most junction with Dr David Brazier and Dr Brunodear had failed to believe in it and support me. No Guiffre, Dr Christie has acted as the source ofchild could have wanted for greater support in pur- numerous practical conversations regarding imaging suing an education than that with which my sib- protocols that have translated into material for bothlings and I have been blessed by our parents. This this text and the imaging manual within the busi-is true inheritance. ness itself. I have indeed learned an enormous amount under your tutelage and that of all the radi- My brother Neil Bright has shared his considerable ologists at NSR. It is a privilege to work with you. knowledge of anatomy and pathology throughoutmy professional life. All those books and gory Midland MRI in Hamilton, New Zealand kindly pro- images you showed me as a child came to some- vided some of the images used in this text. Dr Glenn thing. At least the rest of the family wont mind Coltman and Stephen Butler shared their knowl- me showing them a picture from this one after edge and the companys vast array of images anddinner! protocols, particularly for MR angiography. I am immensely grateful for their time, hospitality, opin-Last, but never, ever the least, to my Wiradjuri ions and access to their database. Warrior. Our mutual respect and intellectual spar-ring has fired the motivation behind what was only Grateful thanks are due to Dr Iain Duncan and Luke in its infancy when we first met. Your trust in Denyer at the Canberra Imaging Group and tomy abilities gave stability when I felt the task all- Vanessa Pineiro at PRP Imaging in Gordon, Sydney consuming and my self-belief wavering. We work for allowing me to visit and collect data from their so very well together. Whatever challenges and sites. Wendy Strugnell at The Prince Charles Hos-despite the adversities, you always manage to pital in Brisbane and Dr Gemma Figtree from theweave with me another line in our cloth. The pub- University of Sydney provided assistance withlication of this book is definitely a golden thread.viii AcknowledgementsPlanning and Positioning in MRI 9. AuthorAnne BrightGrad Dip MRI, BAppScMRI Supervisor, North Shore Radiology & Nuclear MedicineMember Australian Institute of Radiography (AIR)Member of Section for Magnetic Resonance Technologists (SMRT) For my parents, Jack and Irene, who gave each of their children the only real inheritance that matters a sound education and an open and tolerant mind.ReviewersClare BerryMark W StrudwickConjoint Diploma in Diagnostic Radiography,PhD, PGDip Magnetic Resonance Technology, DipPostgraduate Certificate in MRIDiagnostic RadiographyRoyal Brisbane and Womens Hospital, Senior Lecturer,Queensland University of TechnologyDept. of Medical Imaging & Radiation Sciences, School of Biomedical Sciences,Stephen Butler Faculty of Medicine, Nursing and Health Sciences,MHSc(MRI), Member SMRT & NZIMRTMonash University, Vic.Midland MRI, Hamilton, NZ Lawrance YipGail Durbridge MSc Magnetic Resonance TechnologyMScDepartment of Radiology, Queen Mary Hospital,Senior Research Radiographer Hong KongCoordinator MRT Teaching Program,Centre for Magnetic Resonance, Bosco YuUniversity of Queensland Master of Health ScienceMRI, Bachelor of Business, Dip in LawNicole HarrisonMRI Portfolio Manager, Blacktown Hospital, NSWBachelor of Medical Radiation Science (DiagnosticMember of Medical Imaging Advisory Panel,Radiography) Australian Institute of RadiographyBlacktown / Mt Druitt Hospital, NSWKerri OshustMRT (MR)Instructor in MRI Program,School of Health SciencesCoordinator, MRI Second Discipline,Department of Continuing Education,NAIT, CanadaPlanning and Positioning in MRIReviewers ix 10. IntroductionWhen commencing in magnetic resonance imaging, The text endeavours to include images that demon-the range of pulse sequences, variable appearances strate slice orientation on anatomy that is not dis-of pathology and image orientation may overwhelm torted by disease. In cases where pathology may betrainees. The approach taken in the writing of thisevident, image selection has been made to assist thetext reflects the intended audience, namely radiog-student in learning the principles that underpinraphers actually performing the examination, oper- good positioning and anatomical coverage. Theating the scanner. Most, if not all sites are undermajority of scanners are superconducting, requiringthe direction of a radiologist who prescribes pulsea patient to lie on a table, and the text is writtensequences and ultimately reports on the outcomes,from such a perspective. Nevertheless, the guide-but it is the radiographer sitting at the operator lines concerning anatomical coverage and demon-console who must know the imaging planes and strated structures do not change, being pertinentdegree of coverage required, just as they would forregardless of scanner design.an X-ray or CT examination. This text aims toaddress this issue, focusing upon patient position-A final note on terms. Debate exists over the appro-ing and image planning, with a limited description priate term for the person operating the MRIof what may be demonstrated in each scan plane.scanner. This is partially due to variations in terms between the various jurisdictions and the relativeMRI is dictated not only by anatomical region, qualifications. It includes terms such as radiogra-but also by pathological extent and body habitus.pher, operator, imaging practitioner, technicianWhile each site will have a preferred approach for and technologist. The term radiographer is usedscanning each body region, there are basic princi- throughout this text as an all-encompassing meansples that can be learned. Once the basic principlesof inclusion for all individuals performing MRIof good positioning are developed, what wasscans, regardless of their affiliation.once purely rote knowledge will become appliedwisdom, establishing the foundations necessary forthe lateral thought processes necessary to manageSafetycomplex cases. The importance of vigilance in screening every person who enters the MRI environment cannot beA detailed discussion of physics, scan parametersoverstated. Careful and repeated screening (at theand safety is outside the scope of this text. Most time of booking, when registering at reception,sites will have routine scans programmed for their when changing and before entering the scan room)most common examinations. Nevertheless, a briefby the staff at each point provides the best oppor-overview of some of the considerations required in tunity to prevent injury to the patient, supportbuilding a pulse sequence follows and should becompanions and staff.borne in mind by the trainee. More detailed infor-mation is available in the many excellent resourcesNot all sites ask a patient to change into a cottonalready available both in print and via the internet.or disposable paper examination gown, although this is to be encouraged. This simple requirementKinematic imaging of the joints is beyond the scopedramatically reduces the possibility of a patientof this text, but is a useful adjunct in the examina-entering the scan room with objects in their pocketstion of joint instabilities and impingements. Gener- that may be rendered obsolete by the high fieldally, a non-ferromagnetic device is required to fixstrength (e.g. credit cards) or may pose a threat asthe proximal portion of the joint, while allowing aa projectile (e.g. keys, pocket knife). In combinationradiographer to alter the position of the distal joint with removing dental implants and all jewellery, aincrementally. patient divested of all metal ensures maximal fieldx IntroductionPlanning and Positioning in MRI 11. homogeneity to achieve best image quality, as welladministered gadolinium-based contrast media,as limiting the possibility of thermal injury due toespecially when indications point toward renalitems heating during scanning. Even the mostdisease. There is a burgeoning volume of informa-benign-appearing metallic thread (e.g. lurex) can tion related to both contrast media and implantlimit image quality or result in burns. Heavy make- safety. The reader is directed to the many excellentup, especially around the eye, should also be resources available, often at very little cost. A listremoved, particularly when imaging the head toof suggested support resources may be found at theprevent image distortion. Its worth keeping a bottle end of this introduction.of make-up remover in your unit. Caution withpermanent make-up or tattoos, especially aroundthe eyes, is necessary. These common preparationconcepts, while not repeated throughout this text,Artefactsshould be borne in mind when preparing a patientAs with any radiological examination, motion willand the examination room. degrade image quality. Making the patient ascomfortable as possible will minimise the potentialPadding is used to prevent conductive loops forming for motion. Supporting limbs, padding around thebetween skin surfaces, such as at the thighs or head, placing a sponge under the knees to allevi-ankles. Wherever two skin surfaces meet or theate back pain, can all assist in preventing patientskin touches the bore, there is potentially a conduc- motion. Again, use only padding supplied by ative loop; place a MRI sponge between the two reputable MRI vendor. Do not grab a sandbagsurfaces. from the nearest X-ray roomits not alwaysjust sand!Hands on the body or above the head should beseparated, and thermal padding placed between theAnother common artefact encountered by thepatient and the bore of the magnet to preventtrainee in MRI is phase wrap (aliasing). Alwayscontact and possible thermal injury. Note that notcheck the phase direction and assess whether theall padding is MR-safe and some may pose a threatfield of view is sufficient to encompass the anatomy.under certain circumstances. Only sponges suppliedIf not, there are three optionschanging the phaseby a reputable MR supplier should be used withindirection, increasing the field of view or applyingthe scan room.phase oversampling (no phase wrap). Each of theseHearing protection should be provided when oper-carries a potential cost; be sure you are aware ofating a scanner that produces significant noise. Ear- the impact of making a change.plugs and/or muffs may be supplemented bypadding around the head to further minimise noise.Ghosting is due to the pulsation of arterial flowThis will also aid in preventing patient motion causing tracks across an image in the phase direc-during scans of the head or neck. tion. Again, altering the phase direction so that theartefact does not track over the anatomy of inter-Supporting relatives or companions should beest may be an acceptable remedy, but perhapsscreened carefully to ensure that they have removed better would be applying a saturation pulse justall potentially hazardous items and are wearing outside the field of view to null the signal ofonly simple clothing; no belts, no jewellery, nothing inflowing blood. In the head and neck, the satura-in the hair, pockets emptied. tion pulse would be placed inferiorly to null bloodas it flows into the head; in the rest of the body,Considerations for patient safety include checkingthe pulse would generally be applied superior tothe renal function of patients who will bethe field of view.Planning and Positioning in MRIIntroduction xi 12. A saturation pulse is also helpful in nulling theIt is the combination of signal characteristics dem-signal from respiratory motion in the abdomen. onstrated on images in multiple imaging planes thatImages of the abdomen and pelvis will often benefitassists in the determination of disease aetiologyfrom a saturation pulse applied over the subcutane-and differential diagnosis. While inhomogeneitiesous fat of the abdomen or diaphragm. For imaging generated by metallic implants such as spinal fusionof the spine, a saturation pulse placed just anterioror dental implants will degrade image quality, dis-to the vertebra will reduce artefact from swallowing torting anatomy and ruining fat saturation, thisand aortic pulsation, but be careful not to saturate feature can be exploited to better demonstratethe signal if there is a paraspinal lesion.pathological processes such as microscopic bleeds in the brain or iron loading in the liver.There are many other artefacts that may be encoun-tered, including but not limited to truncation, Gibbs The fundamental difference in pulse sequenceartefact and chemical shift. These are less relateddesigns results in entirely differing parameters. Into patient position and slice orientation. A compre- addition, field strength impacts on parameter values.hensive description, explanation and managementRegardless of whether there are pre-loaded scansstrategy for each of these and many other MRIon your scanner, there will be occasions where youartefacts can be found in a physics text.will be required to build or manipulate a pulse sequence to meet the requirements of the particular pathology you are examining, or to ameliorate arte-Image weightingfactual signal anomalies. The radiographer must beImage weighting is a function of pulse repetitionfamiliar with the appropriate range of parameterstime (TR) and echo time (TE) (see table below),for the field strength at which they operate and forcombined with the method employed to generatethe specific type of pulse being used.the echo. Rapid acquisition and relaxation enhance-ment (RARE, also known as fast spine echo, turbospin echo) produces true T2 image contrast, the Imaging coilsrefocusing pulses minimising the effects of fieldDefining anatomical boundaries for MRI provides ainhomogeneities. Gradient echo (GRE, also knownmeans of determining the area for inclusion whenas fast field echo) using refocusing gradient pulses choosing an appropriate radiofrequency coil anddoes not compensate for the effects of field inho- planning a pulse sequence. Each imaging coil willmogeneities, generating T2* contrast. In addition, have a specified field of view that must be takenRARE employs a 90 excitation pulse (or nearly into account by the radiographer when selecting an90), while GRE uses a much lower flip angle, any- appropriate device. Many coils are designed with awhere between 10 and 60. These fundamental particular task in mind, but are generally adapteddifferences impact on scan time, image quality and in clinical use for imaging of more than one regionmost importantly, image characteristics. of the body. Image weighting Repetition time (TR) Echo time (TE) T1ShortShort Proton density (PD) Long Short T2/T2*Long Longxii IntroductionPlanning and Positioning in MRI 13. Radiofrequency coil design has developed dramati- While these coils are suitable for imaging of thecally, and this will no doubt continue. Many sitesbody (e.g. chest, heart, abdomen, hamstrings), theystill use older designs producing images of highmay also be used when patient body habitus orspatial and contrast resolution. The radiographer illness places constraints on traditional positioning.needs to be aware of which coils are receive-only For example, a patient who is unable to lie on theirand which are transmitreceive. A receive-only coil back for an examination of the thoracic spine, maydetects emitted radiofreqency from the body after better tolerate the procedure when allowed to lieexcitation has been induced by the intrinsic body decubitus and imaged using a coil such as that incoil incorporated in the scanner itself. In contrast, Figure I.1.a transmitreceive coil both generates the excitationBreast imaging is performed prone, the breastsradiofreqency pulse and receives the emitted signal.hanging into a cavity surrounded by elements builtVarious coil designs exploiting the benefits of com-into the coil (Fig. I.3). These coils may include sta-bining coil elements have been developed. Linearbilising paddles. Compression is not required forpolarised, circular (quadrature) polarised andMRI of the breast; the paddles simply serve as aphased array coils all have their own advantagesand limitations, which can be studied elsewhere.The important thing to remember is that the protonsclosest to the imaging coil generate the highestsignal. Detecting signal from protons deep withinthe tissues (e.g. within the abdomen) requires a coilof larger dimensions, but this also increases noise.Hence, selecting a coil with a field of view andphysical design that best fits the region of interestis the first step in maximising image signal. Theimaging coils that follow are used as examples onlyof the various forms and designs available.Coils such as those in Figures I.1 and I.2 are suitablefor imaging when a large field of view is required. Figure I.2 Body matrix (Siemens).Figure I.1 8-channel cardiac array (GE Healthcare). Figure I.3 SENSE breast coil 7 elements (Philips).Planning and Positioning in MRIIntroduction xiii 14. Figure I.4 16-channel head-neck-spine coil (GEFigure I.6 Head and neck matrix coils (Siemens).Healthcare).head and 4 coil elements for the neck parts respec-tively. The picture also shows superior end of thespine coil attached to the head and neck coils. Theneck coil may be removed if only an examinationof the head is needed, although it many remain inplace even if you dont need it for a particular exam.More coils with correspondingly more elementsmay be added to these two coils if greater coverageis needed.The longer the examination duration, the moreuncomfortable a patient may become. The abilityto combine elements for multi-region imagingincreases the utility of the individual coil modules,Figure I.5 16-channel head-neck-spine coil, faceand makes imaging of multiple pathologies or clini-and chest elements (GE Healthcare). cal indications less cumbersome for the radiogra-pher and decreases examination times.means of preventing movement during imageacquisition. Patients in whom a lesion is detectedJoints between long bones are best examined usingmay require a MR biopsy, so perforated grids wouldcoils designed for the region of interest. Imaging ofbe used in place of compression. These would typi-the knee or elbow, using the Superman positioncally be applied with more pressure.described in Chapter 5.2, p 186, may be performedwith coils such as those in Figures I.7 and I.8. TheSome coils have a modular design, allowing thechimney in the coil in Figure I.8 makes it suitableradiographer to add elements to increase the fieldfor also imaging the ankle and foot, although dedi-of view for imaging large regions of interest. Figure cated foot and ankle coils have also been designedI.4 is set up to image the spine, but includes anterior (Fig I.9). A wrist coil is shown in Figure I.10.elements (Fig I.5) for imaging of the head and bra-chial plexus. Figure I.6 shows two coils composingA flexible coil (Fig I.11) is available in two sizes. It16 coil elements in total; 12 coil elements for the enables imaging of anatomy that may be distortedxiv IntroductionPlanning and Positioning in MRI 15. Figure I.7 SENSE knee coil 8 elements (Philips). Figure I.9 InVivo 8-channel foot and ankle coil(Siemens). Figure I.8 InVivo HD quadrature extremity coil (GE Healthcare). Figure I.10 InVivo 8-channel wrist coil (Philips).An example by disease or injury, making it difficult to fit a jointis in CS03 into a coil moulded to the usual body contours.(Forearmtumour). Small anatomical areas, such as the digits of the hand or foot, require dedicated coils with a small field of view (Fig I.12). Small dual coils are also useful for examination of the temporomandibular joints using a frame to support the coils (Fig I.13). Imaging coils of the shoulder have possibly the greatest variation in design (Figs I.14I.16). The coils shown here are merely a sample of the many options available. The coil in Figure I.16 may also be used for imaging of other joints, including the hip and elbow. Figure I.11 4-channel small flex coil (Siemens). Planning and Positioning in MRI Introduction xv 16. Figure I.12 Three-inch dual coils (GE Healthcare). Figure I.15 Shoulder coil (Siemens). Figure I.16 Multi-purpose phased array coilFigure I.13 Three-inch dual coils (GE Healthcare). (MEDRAD). A specialised coil may be used for imaging of anatomy deep within the pelvis. Such intracavity coils (Fig I.17) provide a small field of view and high signal of structures close to the receiver, such as the prostate, rectum, uterus and anal sphincters. Coils are generally moulded for the particular region of interest; a rectal coil will sit above the sphincters and is therefore not ideal for imaging of the anal sphincters. These coils may often be coupled with other external coils such as that in Figure I.3, and are disposed of once the examination is complete. Knowing the characteristics of the radiofrequencyFigure I.14 Shoulder coil (Philips). coil being used and the degree of coverage requiredxvi Introduction Planning and Positioning in MRI 17. the associated journals, this organisation provides the widest possible range of educational resources available to the greatest number of people. Make use of the resources on offer and your membership fees will be more than well rewarded. http://www.ismrm.org/smrt/ MRI List Server Free to members and non-members alike, this mail server operated and maintained by the Section for Magnetic Resonance Technologists (SMRT) pro-Figure I.17 Endorectal coil MRI probe for prostate vides contact with other MR imaging professionals(MEDRAD).throughout the world. The cumulative body of knowledge of the individuals in this group repre-for the area and pathology under examination issents an enormous resource that has assisted andcrucial to producing images of high signal quality.enabled the sharing of information in a bipartisanTime spent learning about imaging coil hardwaremanner for over a decade.from texts and papers on this subject will be http://www.ismrm.org/smrt/listserv.htmrewarded with comprehension that will enable theradiographer to resolve many issues due to arte- Society for Cardiovascular Magneticfacts, save time and generate images of high spatial Resonanceand contrast resolution. Specifically for those involved in cardiovascular MRI. This site provides much support for bothSuggested support resourcesmembers and non-members alike, although some resources require membership.The websites listed here are of long standing, highrepute and hence unlikely to cease to exist in the http://www.scmr.org/near future. They offer support to those working MRIsafety.comwith MRI throughout the world, regardless of theirspecific discipline. All websites were accessible on Set up and maintained by Dr Frank Shellock, this14 March 2011. website is invaluable for quickly identifying implant particulars.Section for Magnetic ResonanceTechnologistshttp://www.mrisafety.comWith chapters in the AustraliaNew Zealand and The Adelaide MRI websiteBelgiumNetherlands regions as well as acrossCreated and maintained by Greg Brown, thisthe United States, the Society for Magnetic Reso-resource provides a wealth of information for thenance Technologists (SMRT) has supported MRMR radiographer. It has been an invaluable tool forradiographers throughout the world for twentycountless radiographers over the years and is ayears. With the quarterly Educational Seminars,useful first port of call for any technical or practicalregional meetings, annual international conference concern.held in conjunction with the International Societyfor Magnetic Resonance in Medicine (ISMRM), andhttp://www.users.on.net/~vision/Planning and Positioning in MRIIntroductionxvii 18. Section 3Chest and abdomenChapter 3.1 Mediastinum 993.1.1 Imaging planes: Routine sequences 1013.1.2 Imaging planes: Supplementary sequences 103Chapter 3.2 Heart 1043.2.1 Imaging planes: Routine sequences 1063.2.2 Imaging planes: Supplementary sequences 109Chapter 3.3 Breast 1123.3.1 Imaging planes: Routine sequences 114Chapter 3.4 Liver and gall bladder 1173.4.1 Imaging planes: Routine sequences 1203.4.2 Imaging planes: Supplementary sequences 122Chapter 3.5 Adrenals and kidneys 1243.5.1 Imaging planes: Routine sequences 1263.5.2 Imaging planes: Supplementary sequences 128Chapter 3.6 Pancreas 1293.6.1 Imaging planes: Routine sequences 1313.6.2 Imaging planes: Supplementary sequences 133Chapter 3.7 Aorta 1343.7.1 Imaging planes: Routine sequences 137 19. Chapter 3.1 MediastinumIndications: Mediastinal mass, e.g. thymic enlargement,for whom iodinated contrast is contraindicatedlymphoma, congenital cysts. for CT. Neurogenic lesions, e.g. thoracic meningoceles, Assessment of vascular anomalies of the chestschwannomas, malignant nerve sheath (in conjunction with MRA), e.g. thoracic aortictumours, sympathetic ganglia tumours. dissection or aneurysms. Differentiation between lymph nodes andvascular anomalies, particularly in patientsCervical (cupula, or dome, of)parietal pleura and suprapleuralmembrane (Sibsons fascia) 1st rib Brachial plexus Left subclavian v. and a.EsophagusClavicle Thoracic duct Left brachiocephalic v. Left vagus n. (X) Arch of aorta Thymus gland (seen through mediastinal pleura) Recurrent laryngeal n.Accessory Ligamentum arteriosumhemiazygos v. Left pulmonary a. Bronchopulmonary Left phrenic n. and (hilar) lymph nodespericardiacophrenicPosterior intercostala. and v.v. and a. andMediastinal part ofintercostal n.parietal pleura(cut edge) Gray and white rami Fibrous pericardium communicantes Left pulmonary vv.Costal pleura (cut edge)PulmonarySympathetic trunk ligament (cut)Greater Fat padsplanchnic n.Esophagus and Thoracicesophageal plexus (descending) aorta (covered by mediastinalLeft main bronchus part of parietal pleura) and bronchial a. Diaphragm (coveredby diaphragmatic part of parietal pleura)Costodiaphragmatic recess of pleural cavity Costal part of parietal pleura (cut edge)Figure 3.1 Divisions of the mediastinum.(Netter illustration from www.netterimages.com Elsevier Inc. All rights reserved.)Planning and Positioning in MRI Chapter 3.1 Mediastinum 99 20. Coils and patient considerationslymphoma, lung cancer, breast cancer), MRI maybe considered an appropriate alternative for moni-Contained within the chest between the pleuraetoring of nodal disease, metastatic invasion to theand bounded anteroposteriorly by the sternum andheart or the investigation of cardiac function.thoracic vertebrae, the mediastinum refers to all thecontents of the thoracic cavity except the lungs. Inconsistent breath holds will limit image qualityConsensus for further division of the mediastinal and potentially result in an incomplete examina-compartments has been elusive, with some authorstion. Respiratory gating used with free breathingdescribing anterior, middle and posterior compart-techniques enables image triggering at a consistentments. Other investigators describe a superior com- point within the respiratory cycle. A respiratorypartment with the inferior compartment beingbellows also allows the operator to monitor thedivided into three sections from anterior to poste- patients compliance with breath hold scans, alert-rior. Regardless of the morphologic conventioning the operator to gradual exhalation during imageemployed, delineation of disease may includeacquisition or an inability to hold the breath for tooassessment of the heart, great vessels, thymus, long. It is useful to fit the bellows on every patienttrachea and left and right main bronchi, oesopha- during preparation and to coach each one aboutgus, various nerves and lymph nodes.breathing instructions before the examination.Advantage should be taken of options on scannersThe lack of signal-producing tissues in the lungs that facilitate pre-recorded breathing instructions.makes MRI an unsuitable technique for investiga-tion of most pulmonary disorders, but it may be Cardiac gating may also be useful, particularly fora useful adjunct for the demonstration of medias- demonstration of the mediastinal lymph nodestinal lesions after CT or angiography. Lesions sus- close to the pericardium or thymus. While anatomicpected to involve or originate in the spinal column coverage in this section is quite broad, focus mayoften benefit from MRI in conjunction with CT tobe needed on a specific portion of the mediastinum.fully delineate disease pathogenesis. For patientsDirection from a radiologist should be sought towho are subject to an increased lifetime accumu-ensure the appropriate targeted examination is per-lated risk of neoplastic disease due to breast or formed. A large area surface coil is required (seelung irradiation (e.g. young women with Hodgkins Figs I.1 & I.2).100 Chapter 3.1 Mediastinum Planning and Positioning in MRI 21. 3.1.1 Imaging planes: Routine sequencesPosition: Supine, head first Arms above the head permits a smaller field ofview for long axis imaging (coronal), as well asfacilitating the examination of patients with amore solid body habitus.Other considerations: Patients who suffer from claustrophobia mayprefer a feet-first orientation, if possible.Removing or using only a low pillow underthe head may help the patient feel lessencumbered, keeping distance between theface and top of the bore. The bellows should be positioned over the area Figure 3.3 Axial planned on a sagittal image.of greatest expansion and contraction. (North Shore Radiology) If the bellows is positioned under the anteriorportion of an imaging coil, consider placing thebellows along the side of the chest where theweight of the coil will not restrict its Alignment:movement. Sponges or dielectric pads placed True axial.either side of the bellows also prevent thebellows from being compressed. Coverage:AxialSuperior to inferior: Thoracic inlet to diaphragmatic crura Lateral to medial: Chest wall on each side Posterior to anterior: Thoracic spinous processes to sternum. Demonstrates: Contents of the mediastinum, comparative with direct acquisition CT images. Morphology of the great vessels and heart, with specific examination of each of the inferior mediastinal compartments. Lymph node location and size.Figure 3.2 Axial planned on a coronal image.(North Shore Radiology)Planning and Positioning in MRIChapter 3.1 Mediastinum 101 22. Coronal Alignment: True coronal.Coverage: As for axial plane.Demonstrates: Contents of the mediastinum, comparable withreformatted CT images. Morphology of the great vessels and heart,with delineation of the superior and inferiormediastinal compartments. Lymph node location and size. Costophrenic angles and lung apices.Figure 3.4 Coronal planned on an axial image.(North Shore Radiology)Figure 3.5 Coronal planned on a sagittal image.(North Shore Radiology)102 Chapter 3.1 Mediastinum Planning and Positioning in MRI 23. 3.1.2 Imaging planes: Supplementary sequencesSagittalAlignment: True sagittal.Coverage: As for axial plane.Demonstrates: Contents of the mediastinum, comparable withreformatted CT images. Morphology of the great vessels and heart,with delineation of the superior and inferiormediastinal compartments.Figure 3.6 Sagittal planned on a coronal image.(North Shore Radiology)Figure 3.7 Sagittal planned on an axial image.(North Shore Radiology)Planning and Positioning in MRI Chapter 3.1 Mediastinum 103