COMPuted tomography RADIOLOGY - PowerPoint Presentation

1. COMPuted tomographyRADIOLOGYResident Board ReviewJanuary 23rd, 2014Jo-Annie Letendre, DVM

2. OutlineBasic principles of CTUse of CT in ECCReview of the paper:Radiology of thoracic trauma in the dog and catReview of the paper:Comparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisReview of the paper:Multidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsDiscussion

3. Basic principles of CT

4. Basic principles of CT Definition:Creation of a transverse tomographic section (or slice) of the body using a rotating fan beam, detector array, and computed reconstructiontomos = slice digital image

5. Basic principles of CTComponentsOperating consoleComputerGantryX-ray tubeRadiation detection system

6. Basic principles of CTPrinciples of operationFirst to fourth generationsEBCTFast imaging; < 100 msMicrowave accelerated electron beamCardiac imagingSpiral CT -19893rd or 4th generation CT imagerPatient couch is movedMultislice CT/multidetector – 1990sRapidHigh resolution of a large tissue volumeHigh-quality 3D reconstructionCUHA: Toshiba Aquilion Large-Bore, 16-slice16-slice = 16 detectors; able to take 16 slices of anatomy/rotation

7. Basic principles of CTAdvantages of CT over radiographsBetter contrast resolutionBy blurring tissues above and below the focal planeNo superimposition of tissueLess scatter radiation3D imaging

8. Basic principles of CTRadiology = 2D: pixel (mm2)Pixel = picture elementEach cell of a matrixCT = 3D: voxel (mm3)Voxel = volume elementVoxel = pixel size x slice thicknessNormal slice thickness: 1-10 mmMatrix: 512x512 or 1024x1024

9. Basic principles of CTHounsfield scale Tissue density in different shades of grey in relation to its x-rays absorptionHigh HU (bone): brightlow HU (air):darkCT numbersNumbers used to define relative attenuation coefficient for each voxel as compared with attenuation coefficient of water.

10. Basic principles of CT256 shades of grey; eye: 20 Window width (WW)Range of CT numbers displayedWindow level (WL)Central value of the WWBONESOFT TISSUEWide WWNarrow WWGray imageLow contrastBlack&white imageHigh contrast

11. Basic principles of CTCONTRAST AGENTSTo improve the visibility of internal structuresIodinated contrastIonic: hyperosmolarNonionic: low-osmolar or iso-osmolarFewer side effectsContrast-induced nephrotoxicityCaution with dehydrated patients; patients with renal disease

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13. Use of CT in ECCRespiratory system

14. CT pulmonary angiography (CTPA)Use of CT in ECCCTPA = gold standard for PTE diagnosis in human medicineRapid, spiral thoracic CT, peripherally infused contrast media with a pressure injector (peak enhancement of the pulmonary arteries)Diagnostic criteria for PTE:Complete pulmonary arterial occlusionCentral intraluminal arterial filling defect(s)Peripheral intraluminal arterial filling defect(s)

15. CT pulmonary angiography (CTPA)Use of CT in ECCSpiral CTPA using 16-slice CT-scannerButorphanol 0.3 mg/kg IVCTPA can be used to confirm and rule out PTE in dogs under sedation, even in at-risk patients with respiratory distress. Spiral CTPA using 16-slice CT-scannerNo sedation; obtunded mentationHypoattenuating luminal-filling defects consistent with multiple PTE

16. CT pulmonary angiography (CTPA)Use of CT in ECC

17. Upper airway obstructionUse of CT in ECC10 cats with clinical signs of upper airway obstructionVetMouseTrap™No sedation, no anesthesia7 cats: intramural upper airway masses2 cats: laryngotracheitis1 cat: laryngeal paralysis

18. Cats with thoracic diseaseUse of CT in ECC54 cats with recent history or current clinical signs of respiratory diseaseVetMouseTrap™ – no sedation/no anesthesia41/54 were dyspnic44 cats also had thoracic radiographsCorrect final diagnosis: 77.8% with CT; 58% with xraysAdditional information provided with CT in 74% of catsDiagnosis:Lung neoplasiaCardiomyopathyLower airway diseaseMediastinal massInfectionTraumaHernia

19. Dogs with upper airway obstructionUse of CT in ECC17 dogs with CS attributed to upper airway obstructionNon sedated or sedated CT, without endotracheal intubationDiagnosis:Laryngeal paralysisLaryngeal collapseTracheal hypoplasiaTracheal collapseTracheal stenosis

20. Dogs with acute abdominal signsUse of CT in ECC18 dogs with acute abdominal signsWithout sedation or with sedation if poor quality study 8 without sedation; 10 with light sedationScan time < 10 minutes16/18 CEMD CT: fair to excellent diagnostic quality2: poor qualityMotion artifactsBeam hardening from previously administered barium contrast agent

21. Traumatic brain injury –CT vs MRIUse of CT in ECCMRI is generally superior in identifying lesions, exceptSkull fractureSubarachnoid hemorrhageMRI is also more sensitive for intraparenchymal injury: edema, axonal injury, contusions, hematomasCT is most commonly used FasterEasierImaging of the spines/pelvis/chest abdomen Abnormalities less well seen on CT do not appear to be clinically significant

22. Traumatic brain injury –CT vs MRIUse of CT in ECC10 dogs with TBI; MGCS of 15 (mild), CT performed9/10 had abnormalities on CTFractures (8)Frontal, parietal, temporal, multiple bones, osseous bullaDepressed, elevated, linear or compound Hydrocephalus (4)Parenchymal damages (3)Hemorrhage (1)Epidural; associated with multiple calvarial fractureMass effect (1)

23. Radiology of thoracic trauma in the dog and catPaper review

24. INTRODUCTIONRadiology of thoracic trauma in the dog and catBlunt thoracic traumaInertial forcesSpalling effect (or implosion)Dorsoventral and lateral viewsThoraxAir and bones: high inherent contrastHigh kV/low mAs techniqueStatic evaluation Serial xrays may be valuable

25. Classification thoracic traumaRadiology of thoracic trauma in the dog and catThoracic wall Pleural space Pulmonary parenchymaMediastinum

26. Radiographic signsRadiology of thoracic trauma in the dog and catThoracic wall Rib fracture/laceration, SQ emphysema, vertebral/sternebral fracture/luxation, visceral herniationPleural spacePneumothorax: best view In lateral; between heart and sternum (dogs) ; lucency, lobe collapseTension pneumothorax: large volume of air, pulmonary collapse and diaphragm flattening, mediastinal shiftHemothorax: increased opacity, decreased visualization of cardiac silhouette/diaphragm, widened interlobar fissuresDiaphragmatic hernia: displacement of thoracic viscera, cranial displacement of abdominal viscera (abdominal xrays, positive contrast gastrography or peritoneography)

27. Radiographic signsRadiology of thoracic trauma in the dog and catPulmonary parenchymaContusions = rapid compression and decompression of the lungs  Hemorrhage and edema: focal, multifocal, lobar or generalized increase in opacity; can be more marked (clinically and xrays) in the 4-6 hours following traumaLacerations: focal or multifocal cavitary lesions (air or blood); periphery of the lung; resolve w/in a few days

28. Radiographic signsRadiology of thoracic trauma in the dog and catMediastinumPneumomediastinum: visualization of the borders or the oesophagus, trachea or mediastinal vessels, pneumopericardium, pneumoretroperitoneum/cervical emphysema (direct extension)Mediastinal hemorrhage: widening of the cranial mediastinum, displacement of the trachea.Tracheal avulsion: Focal deviation, narrowing of the trachea, focal air-filled cavity superimposed on the trachea, pneumomediastinum

29. Radiographic signsRadiology of thoracic trauma in the dog and catTrauma patientsRadiographs?CT?Ultrasounds?

30. Comparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisPaper review

31. IntroductionComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisPublished in the Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine2014Aim of the study: to explore the value of whole-body CT(WBCT) in major trauma patients (MTPs)From 1980-201311 trials – 26 371 patients

32. BackgroundComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisLeading cause of mortality Reduction of the diagnostic interval = better prognosisConventional evaluation methods:Thoracic and pelvic xraysFASTOrgan-specific CT misdiagnosis and time-consuming

33. BackgroundComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisIncreased use of WBCT in trauma patientsFrom 5% in 2002 to 46% in 2010Radiations exposureShould WBCT be used as an initial assessment tool in MTPs?Contradictory results regarding effect of WBCT on mortality in MTPs

34. MethodsComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisMeta-analysisPrimary endpoint: all-cause mortality rateSecondary endpoints: time spent in the ED, duration of mechanical ventilation, ICU/hospital length of stay, incidence of MODS/MOF

35. ResultsComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisWBCT was associated with a lower mortality rate and a shorter stay in the ED.No effect of WBCT on ICU/hospital length of stay. WBCT was associated with longer duration of mechanical ventilation and higher incidence of MODS/MOF.Due to decreased mortality?Higher level of injury severity score

36. DiscussionComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisAdvantages of WBCTHigher accuracyReduces interval time between patient’s arrival and the end of life saving procedures/end of diagnostic procedures/beginning of emergency surgery.Possible to detect all injuries with one testFaster

37. Limits of the studyComparison of whole-body computed tomography vs selective radiological imaging on outcomes in major trauma patients: a meta-analysisObservational, non-randomized studiesDifferences between 2 groups, especially ISS valuesImproved survival because of use WBCT?Confounding factors: type of scanners, scanning methods, indications for WBCT, different inclusion criteria, location of the scanners, publications bias.

38. Multidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsPaper review

39. IntroductionMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsTrauma: 4th most common cause of mortality in USA and western EuropeXrays:Suboptimal for vascular and nonvascular thoracic injuriesUnderestimation of the severity/extent of injury/misdiagnosis

40. IntroductionMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsMDCTMore sensitive in the detection/characterization of injuriesOther body regions at the same timeFasterBetter outcomeRadiation exposureRisks associated with contrast media administrationAim of the paper: To review and illustrate MDCT findings of traumatic chest injuries

41. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsPulmonary contusions

42. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsPulmonary laceration

43. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsTracheobronchial laceration

44. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsLarge chest vessels lesions

45. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsHemothorax/pneumothorax

46. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsHemopericardium/pneumopericardium

47. Thoracic trauma injuries seen on CTMultidetector Computer Tomography: Evaluation of Blunt Chest Trauma in AdultsChest wall/diaphragm trauma

48. DISCUSSIONShould we use WBCT in our trauma patients (as an initial diagnostic tool)?Should we use WBCT in all trauma patients or only in patients more severely affected?Overnight WBCT?Localization of CT room/radiology room - ER

49. Questions?