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Traumatic Brain Injury Pearls and Pitfalls (2014)

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Five pearls and pitfalls in using head CT for diagnosis of traumatic brain injury. This was presented at the 51st Annual Scientific Meeting of the Royal College of Radiologists of Thailand (6 Aug 2014)

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Traumatic Brain Injury Pearls and Pitfalls (2014)

  1. 1. Rathachai Kaewlai, MD Ramathibodi Hospital, Mahidol University For the Annual Meeting of the Royal College of Radiologists of Thailand 6 September 2014, Centara Grand @CentralPlaza Ladprao, Bangkok
  2. 2. www.ThaiRSC.com
  3. 3.  Leading cause of disability and mortality from trauma  Young individuals, many life-year losses  80% presenting at Emergency Department  Timely diagnosis and management crucial for patient outcome
  4. 4.  What to report on a head trauma CT?  Primary injury  Secondary effects  Skull and skull base fractures  Quantification of injuries and prognostic/ management significance
  5. 5.  Poor prognostic signs on CT  EDH > 150 mL1  SDH > 10 mm thick, midline shift > 20 mm 2,3  Temporal or bilateral IPH4  IPH + SDH4  DAI5 1Rivas JJ, et al. Neurosurgery 1988;23:44-51 2Servadei F, et al. Br J Neurosurg 2000;14:110-6 3Zumkeller M, et al. Neurosurgery 1996;39:708-12 4Wong GK, et al. Br J Neurosurg 2009;23:601-5 5Adams JH, et al. J Neurol Neurosurg Psychiatry 1991;54:481-3
  6. 6. Joseph B, et al. J Trauma Acute Care Surg 2014;76:965-9
  7. 7. Joseph B, et al. J Trauma Acute Care Surg 2014;76:965-9 Focal neurologic examination, abnormal pupil, GCS < 12 Imaging findings Imaging plan
  8. 8.  Integration of patient’s history, neurologic exam and initial CT results for Rx plan  Easy to assign category (in this paper, only 0.7% were wrongly grouped)  Reduce use of repeat CT (28%)  Reduce number of neurosurgical consultation (35%)  Reduce number of admission (10%)  For radiologists, we now realize what are significant and should be reported
  9. 9.  Skull encases the brain  Brain immersed in CSF  Cellular cohesiveness of brain  Skull surface and dural reflections  Blunt impact by moving object  Moving skull vs stationary object  Rotational translation and deceleration  Coup injuries = superficial  Contrecoup = deep Images from Wikipedia.org
  10. 10. One day later
  11. 11. FLAIR T2W
  12. 12.  Knowing biomechanics of closed TBI important for detection of lesions and forensic purpose  Minimal brain lesions might complete the mosaic for reconstruction of biomechanical condition
  13. 13.  Wei SC, et al. AJNR 2010  213 NCCTs ▪ 32 cases with traumatic ICH = 104 foci on either axial or coronal images ▪ 80 foci were true-positive lesions ▪ 15 true positives not detected on axial images (15/104 = 14%, in 8 patients) ▪ 14 false-positive findings on axial but excluded on coronal
  14. 14.  Axial images are less accurate in areas  Parallel to axial image plane (esp immediately adjacent to bony surfaces)  Common areas where false negatives occur  Floor of anterior cranial fossa  Floor of middle cranial fossa
  15. 15.  Vertically oriented lesion easier to detect on coronal reformation than axials
  16. 16.  Horizontal skull fracture
  17. 17.  Horizontal skull fracture
  18. 18.  Enable us to be certain about diagnosis
  19. 19.  Lesion detection  Floor of anterior and middle cranial fossae  Tentorial lesions  Horizontal skull fracture  Vertically oriented lesions  Enable us to be certain about diagnosis
  20. 20.  To control elevated ICP in severe TBI  Removal of a large portion of frontal-temporal-parietal- occipital skull bone (12x15 cm)  Underlying dura opened in stellate fashion to bone edge. Scalp flap was closed without duroplasty Kolias, A. G. et al. (2013) Decompressive craniectomy: past, present and future Nat. Rev. Neurol. doi:10.1038/nrneurol.2013.106
  21. 21.  EDH after and remote to decompressive craniectomy (DC)  Upon opening skull -- relief of tamponade effect and hemorrhagic expansion of injured meningeal artery, dural vein or fractured diploe  Evolve during operation  May present during or after operation  Can be fatal. Often need 2nd operation
  22. 22.  Su TM, et al. J Trauma 2008  Case series of 12 patients  Contralateral DEDH occurred after decompressive craniectomy  10/12 found to have contralateral calvarial fx on preoperative CT  12/12 found to have fx at surgery
  23. 23.  Talbott JF, et al. AJNR 2014  Retrospective review of 203 patients who had decompressive craniectomy for TBI  6% had DEDH ▪ Age 32 +/- 13 years, two thirds had severe TBI, mostly high impact injuries ▪ Time from sx to postoperative CT = 13 h ▪ All had contralateral calvarial fx on preoperative CT at site of DEDH
  24. 24.  Talbott JF, et al. AJNR 2014  Large size (mean volume = 86 mL, mean thickness = 2.5 cm)  Mean midline shift = 10 mm  Site of DEDH ▪ Contralateral to side of craniectomy (10/12) and bilateral (2/12) ▪ All DEDH at site of calvarial fx
  25. 25. Contralateral skull fracture > 2 bones – 41 times to develop DEDH following DC Talbott JF, et al. AJNR 2014
  26. 26.  Incidence 4.5-6.8% in patients with TBI undergoing DC  Predictor = contralateral calvarial fx (esp. >2 bones involved)  Surgeon should be alerted to  Risks of intraoperative brain swelling through craniectomy defect  Need for early postoperative CT
  27. 27. Head injury, repeat CT per protocol Initial CT done 6 hours ago: Right SDH (5 mm thick) and small cortical SAH. Admission GCS = 13, now stable Do we need to repeat CT again?
  28. 28.  CT is the first-line imaging study “rapidly acquired” and “accurate for significant intracranial hemorrhage”  First CT done as soon as possible after ED arrival  When first CT shows ICH and the patients is observed, do we need repeat (F/U) CT?  Value of repeat (2nd) CT - controversial
  29. 29.  Unexpected changes or findings can be beneficial in management of TBI patients  Increase of patient exposure to ionizing radiation  Misallocation of resources  Elevation of healthcare cost Cartoons from buildingmbrand.wordpress.com
  30. 30.  Well, it depends....  Reljic T, et al. J Neurotrauma 2014  110 references in PubMed thru 2012 reviewed  Meta-analysis of 41 studies = 13 prospective + 28 retrospective = 10,501 patients with TBI
  31. 31. Prospective studies Retrospective studies Progression of injury 31% (15-50) 28% (24-33) Change in management 11.4% (5.9-18.4) 9.6% (6.5-13.2) Change in ICP monitoring - 5.6% (2.2-10.5) Change in neurosurgical intervention 10.7% (6.5-15.8) 5.2% (3.3-7.5) Significant heterogeneity of data led to subgroup analysis Reljic T, et al. J Neurotrauma 2014
  32. 32.  Mild HI Prospective Retrospective Change in management 2.3% 3.9% Change in ICP monitoring - 1.2% Neurosurgical intervention 1.5% 2.4% Reljic T, et al. J Neurotrauma 2014
  33. 33.  Moderate HI Prospective Retrospective Change in management 15.3% 18.4% Change in ICP monitoring - 0% Neurosurgical intervention - 8.2% Reljic T, et al. J Neurotrauma 2014
  34. 34.  Severe HI Prospective Retrospective Change in management 25.3% 19.9% Change in ICP monitoring - 13.8% Neurosurgical intervention - 8% Reljic T, et al. J Neurotrauma 2014
  35. 35.  Change in management mostly in moderate-severe head injury Prospective Retrospective Mild HI 2.3% 3.9% Moderate HI 15.3% 18.4% Severe HI 25.3% 19.9% AVERAGE 11.4% 9.6% Reljic T, et al. J Neurotrauma 2014
  36. 36. Good images can be achieved even with lower radiation dose! CTDIvol 46, DLP 738 CTDIvol 71, DLP 1188
  37. 37. There is no safe dose of radiation. - Edward P Radford, MD Scholar of the Risks from Radiation
  38. 38. Procedures Effective Dose (mSv) Risks CXR (PA), extremity XR <0.1 Negligible Abdomen XR, LS spine XR 0.1-1 Extremely low “death from flying 7200 km” Brain CT, single-phase abdomen CT, single-phase chest CT 1-10 Very low “death from driving 3200 km) Multiphase CT 10-100 Low Interventions, repeated CT >100 Moderate
  39. 39. Most sensitive Lymphoid tissue, bone marrow, GI epithelium, gonads, embryonic tissues Skin, vascular endothelium, lung, kidney, liver, lens (eye) CNS, muscle, bone and cartilage, connective tissue Least sensitive Ref: ICRP 2007 Tissue Sensitivity  ~ rate of cell proliferation  Inversely ~ to age  Inversely ~ to degree of cell differentiation  Higher dose = more damage  Young = more damage
  40. 40. Imaging exam ordered by referring physician Vetting/protocoling by radiologist Scanning Post-processing Monitoring of quality ?????????????????????
  41. 41. Imaging exam ordered by referring physician Vetting/protocoling by radiologist Scanning Post-processing Monitoring of quality Medicineworld.org Technical parameter change  Avoid Z-creep (unnecessary coverage and scan phases)  Make standard protocols available in CT workstations for every techs to use  Reduce mAs  Use automatic tube current modulation  Reduce kVP (esp for CTA, stone protocol)  Incorporate patient size, age and indication into making a protocol (work with your physicists)
  42. 42.  Tube current (mA)  Tube voltage (kVp)  Scan length  Detector collimation  Table speed  Pitch  Gantry rotation time  Automatic exposure control  Use of shielding
  43. 43.  Reduce mAs decreases radiation dose  mA: effects noise only 60 50 40 30 20 10 0 Changes in Dose (CTDIw) as a Function of mAs Fixed kVp 0 200 400 600 CTDIw Head (mGy) CTDIw Body (mGy) mGy mAs
  44. 44.  Reduce kVp decreases radiation dose BUT has effect on both noise and attenuation 60 50 40 30 20 10 0 Changes in CTDIw as a Function of kVp Fixed mAs 0 50 100 150 CTDIw Head (mGy) CTDIw Body (mGy) Nakayama Y, et al. Radiology 2005 McNitt-Gray MF. Radiographics 2002
  45. 45.  Radiation dose is directly proportional to scan volume Extra volume due to lack of gantry adjustment at time of scanning
  46. 46. Imaging exam ordered by referring physician Vetting/protocoling by radiologist Scanning Post-processing Monitoring of quality Jenkinsclinic.org Some methods to reduce image noise (make a better-looking study)  Use smooth kernels  View thicker slices  Use iterative reconstruction (IR)
  47. 47.  Current CT reconstructs images from raw data using filtered back projection (FBP). Faster processing time traded with image noise  Iterative reconstruction (IR) allows less noisy images but with longer processing  Same raw data processed with…  FBP may look noisy  IR appears less noisy Korn A et al. AJNR 2012 FBP IR, 30% dose reduction
  48. 48. Imaging exam ordered by referring physician Vetting/protocoling by radiologist Scanning Post-processing Monitoring of quality Blog.vpi-corp.com Monitoring of study quality and dose by imaging team (techs, physicists and radiologists)  Send “Dose Report” into PACS  Educate radiologists and trainees about dose parameters and standards  Regular updates of CT protocols
  49. 49. CTDIvol - Dose indicator for CT - Accounted for dose gradient, helical pitch, single tube rotation DLP - CTDIvol x scan length - Estimation of effective dose
  50. 50.  Example: Effective Dose = DLPx0.0023 = 1.7 mSv  Typical head CT DLP 1100 mGy.com or ~2.5 mSv  Annual non-medical background radiation ~3 mSv
  51. 51. Before 2010 Dose (median, range) n=490 2011-2013 Dose (median, range) n=564 Median dose reduction (%) P value CTDIvol (mGy) 109 (109-140) 51.5 (17-120) -53% <0.01 Total DLP (mGy-cm) 2232 (1482-6121) 943 (268-4323) -57% <0.01 Effective dose (mSv) 4.7 (3.1-12.8) 2 (0.6-9.1) -57% <0.01
  52. 52.  Brain Injury Guidelines (BIG)  Coup-contrecoup injury  Value of coronal reformation  Delayed EDH after decompressive craniectomy  Repeat head CT  Radiation dose

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