BASIC CONCEPTS IN DIAGNOSTIC IMAGINGJ.J. Jimenez, M.D.A. Tamrazi PhDCarle Clinic AssociationUniversity of Illinois College of Medicine

OutlineIntroductionX-RaysFluoroscopyGIGUCTMRInnovative Modalities

Modalities Available in RadiologyPlain Film / X-Ray/MammographyFluoroscopyUltrasoundCTMRINuclear Medicine/Molecular ImagingAngiography/Interventional

Relative Cost of Imaging Studies

Relative Availability of Diagnostic Imaging

TeachingHospitalxxxxxxxxxxxxxxxxxxxxxxxxxxxxUrban HospitalxxxxxxxxxxxxxxxxxxxxxxxxxxxSuburbanCommun-ity HospxxxxxxxxxxxxxxxxxxxxxxxRural HospitalxxxxxxxxxxxxxxxxxxPlain FilmFluoroU/SCTNMMRIAngio-interven-tional

X-RaysDiscovered in 1895 and still used todayMost widely performed imaging examX Rays are emitted and detected in cassetteCassette can generate either a film or a digital imageFilms are kept on file or in a digital archive

Most Useful Applications for Plain X-RaysChestMusculoskeletalAbdomen: limited usefulness

Plain X-RaysProsConsWidely availableInexpensiveDoesnt require advanced technologist knowledgeCan be performed quicklyPortableIonizing RadiationRelatively insensitiveRequires patient cooperation

FluoroscopyUtilizes X-RaysReal-time imagingUtilizes image intensifier Involves use of contrast agents

Main Uses of FluoroscopyGastrointestinal ImagingGenitourinary ImagingAngiographyOtherIntraoperativeForeign body removalMusculoskeletal

FluoroscopyProsConsWidely AvailableInexpensiveFunctional and AnatomicNo sedation requiredRequires ingestion/injection of contrastPatient cooperationTime consuming

Gastrointestional FluoroscopyEsophogram/Barium SwallowModified Barium Swallow/DysphgiagramUpper GISmall Bowel SeriesEnteroclysisContrast EnemaDefecography

Single Contrast vs Double ContrastSingle ContrastGenerally uses just thin BariumDistends lumen with high density materialEasier for patient/less mucosal detailDouble Contrast/Air ContrastThick barium coats lumenEffervescent tablets ingested to distend lumen with airProduces see-through images with greater mucosal detail Greater sensitivity for small lesions, polyps, ulcers

Single ContrastBarium EnemaDouble ContrastBarium EnemaSingle Contrast vs Double Contrast

Contrast Materials for GI ExamsBarium SulfateThick: used in double contrast studiesThin: used in single and double contrast examsPaste: mod Ba swallow and defogographyGastrograffinFull stregnth: rarely usedDilute

Gastrograffin Swallow StudyBarrium Swallow StudyBarium vs Gastrograffin

Barium SulfateMost widely usedBetter images than gastrograffinChalky tastePeritonitis may develop if perforationIf delayed transit, may form concretions in colon

GastrograffinWater solubleFoul TastePoor mucosal coatingBasically used for R/O obstructionWont cause peritonitis if perforationMay cause severe chemical pneumonitis if aspiratedOsmotic pressure draws fluid into bowel lumenProgressive distention in small bowel obstructionTherapeutic enema in constipation

Patient Factors in GI FluoroscopyAbility to ingest contrastIn order to get high quality images, a relatively large volume of contrast needs to be ingested fairly quicklyMobilityMultiple positions required for GI exams, particularly double contrast exams.Limited mobility = less diagnostic imagesWeightTables have weight limitsRequires maximal radiographic technique and exposure is often suboptimal

Esophogram or Barium SwallowEvaluates pharynx and esophagusLimited evaluation of stomachDouble or Single ContrastMucosal contour and Motility

Modified Barium SwallowAKA Dysphagiagram and at Carle cookie swallowPerformed with Speech PathologistBarium administered in various bolus consistencies ranging from liquid to solidEvaluates swallowing mechanismEvaluates for aspirationPerformed on videotape

Modified Barium Swallow

Upper GI ExamEvaluates esophagus, stomach and duodenumDouble or Single ContrastCan be combined with small bowel seriesLargely replaced by endoscopy and cross-sectional imagingFairly insensitive

Small Bowel SeriesPatient drinks 2 cups of thin BaOverhead films obtained at routine intervalsThe Ba column is followed through until it reaches the colonTransit time, mucosal contour, bowel loop distribution are evaluated.Insensitive for small masses

Small Bowel Series

Small Bowel EnteroclysisDouble Contrast Small Bowel SeriesNGT placed at duodenal-jejunal junctionBa injected followed by methylcelluloseSee-through appearance to small bowelGreater sensitivity for small masses and mucosal lesionsPatient discomfort related to NGT and diarrhea

Contrast EnemasBarium or GastrograffinDouble contrast or single contrastGenerally less sensitive than endoscopyRequires bowel prep to assess for mucosal lesionsRequires some element of patient cooperation

Single ContrastBarium EnemaDouble ContrastBarium EnemaContrast Enemas

DefecogramBarium paste is inserted into rectumPatient is asked to defecate under fluoroscopyAno-rectal and pelvic floor dynamics can be assessedRectocele, intussusception, pelvic floor relaxation, stress incontinence

Genitourinary FluoroscopyCystogramVoiding cystourethrogramRetrograde urethrogramHysterosalpingogram

CystogramUsually in adult patientsLooking for tear or intraluminal massCatheter placed and bladder filled with contrast to capacity: usually 300-500 ml.Spot films obtained when fullPost void film: usually overhead

Cystogram with Intraperitoneal RuptureCystogram

Voiding CystourethrogramVCUGUsually in children with history of UTISearching for vesicoureteral refluxIn males, evaluate for urethral abnormalities: posterior urethral valvesSame as cystogram except when full patient voids under fluoro with spot films

Retrograde UrethrogramRUGMale patientsPelvic TraumaPost-infectious: STD- looking for strictureDifferent techniquesMeatus occluded and contrast injected into urethra under fluoro

Retrograde Urethrogram RUG

HysterosalpingogramUsed to evaluate endometrial canal and fallopian tubes Infertility and uterine anomaliesDye injected into cervical os under fluoroInjection continued with goal to opacify the fallopian tubes and spill contrast into peritoneum

Musculoskeletal FluoroscopyFracture/Dislocation reductionHardware placement in the ORFlexion/Extension views of c-spineArthrographyMay be performed in conjunction with MRI or CT

Techniques Relevant to MSK RadiologyRadiography (routine and specialized views)CTMRIUSDensitometryInterventional procedures (arthrography, percutaneous biopsy/vertebroplasty)

MRISagittal Knee T1 WeightedMSK RadiologyVertebroplasty

Computed Tomography (CT)Cross Sectional imaging modalityMobile X-ray tube that rotates around a ptSlices of X-ray transmission data reconstructed to generate imageData displayed in multiple window settings (lungs parenchyma, bone, etc.)Density measurements/Hounsfield Units analyze chemical component of tissueHU: -150-0 = fat, 0 = water, 0-20 = serous fluid, 45-75 = blood, 100-1000 = bone/calcium

CT Contrast AgentsIntravenous contrast---iodinated Differentiate blood vessels vs. vascular internal organsEnteric contrast---barium Differentiate bowel vs. intra-abdominal fluid/massesRectal contrast Retrograde urinary bladder contrast

CT ApplicationsNeuro-imaging-Acute head trauma, acute intracranial hemorrhage-Low sensitivity for early ischemic stroke, intracranial metastatic disease, white matter degenerative disease Head and Neck imaging-Soft tissue of neck, paranasal sinuses, temporal bone imaging, orbital wall imaging

CT ApplicationsBody Imaging -Chest, Abdomen, Pelvis (with enteric and IV contrast)Pulmonary nodules, Renal Calculi (without contrast)Acute appendicitis (with enteric and IV contrast)Specialized protocols:-Liver masses, pancreatic tissue, renal masses, adrenal masses

CT ApplicationsAcute Abdomen-decrease rate of false laparotomy proceduresTrauma Spine Imaging (cervical, thoracic, lumbar)Other osseous structures (pelvis, extremities)Vascular Imaging-CT angiography--- i.e. coronary arteries

CTAxial, with oral contrast in stomach

CTPETPET/CT

CTA(CT Angiography)CT Cardiac ImagingThe Power of CT

Magnetic Resonance Imaging (MRI)Multi-planar scanningWithout ionizing radiationImages generated using powerful magnets and pulsed radio waves passing through the bodyData from Pts body used to generate image Field strength of magnets 0.3-3.0 Tesla

MR Contrast AgentsIntravenous contrast---Gadolinium chelate-based contrast agentsGadolinium is a paramagnetic lanthanide that is toxic as a free metalContrast to evaluate BBB, intracranial edema and hemorrhage Novel agents being developed as tagged Monoclonal antibodies for Molecular Imaging

MR ApplicationsNeuro-imaging-Excellent tool due to high soft tissue contrast resolution-Abundant water content of CNS allows for imaging soft intracranial tissue Head and Neck imaging-Multi-planar capability allows for monitoring extent of disease-Differentiating subtle soft tissue boundaries of head and neck

MRIAxial, T2-Weighted

MR ApplicationsBody Imaging -Thorax: mediastinal, hilar, chest wall abnormalitiesLimited lung imaging due to artifactsNew advances in breast imagingPotentials for cardiac MRI with coronary MR angiography

MRIBreast Imaging

MR ApplicationsMSK Imaging- High sensitivity for neoplastic, inflammatory, and traumatic conditions of bone and soft tissue- T1-weighted---fluid collections and abnormalities in fatty marrow- T2-weighted---lesions in both marrow and soft tissue

MRISagittal, T1-Weighted

Innovative ModalitiesConstantly evolving face of radiologyNew contrast agents for CT and MRMolecular Imaging- Imaging molecular events---enzymatic activity, receptor binding, cellular eventsInterventional Radiology and Interventional Neuroradiology

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