Optimizing Thoracic Imaging

1. Optimizing Thoracic Imaging July 1, 2009 NSMC Radiology Department Meeting Bruce G. Stewart, MD Radiologist Commonwealth Radiology Associates

2. Presentation Originally Prepared for NSMC ED Staff and Presented to them at their Faculty Meeting on June 18, 2009

3. Objectives • Review types of thoracic CT/CTA exams • Show examples of thoracic pathology • Optimize ordering of CT scans to answer clinical question • Reduce radiation exposure by accurate ordering

4. Importance of History • Allows us to tailor the exam with accurate protocoling • Allows us to answer your clinical question most appropriately • Minimizes inaccurate interpretation • Minimizes repeat exams & unnecessary radiation exposure • Include: • Signs & Symptoms • Diagnosis in Question

5. ED CT Scanner • GE 64 Slice Volume CT • Fast scanner! • Whole body trauma CT in 10 seconds • Reduces cardiac motion, respiratory motion & patient motion • Thinner slices • Better reformats • More confident diagnosis • Less contrast needed

6. Types of Chest CT/CTA • General Chest CT (I- or I+) • Chest CTA for Pulmonary Embolus (I+) • Chest CTA for Aortic Dissection (I- & I+) • HRCT Chest CT for Interstitial Lung Disease (I-)

7. General Chest CT • I-: Foreign body, granuloma, calcified nodule, ? Nodule on CXR, contrast allergy, low eGFR • I+: Lung cancer, metastatic disease, lymphoma, mediastinal disease, adenopathy, trauma, SVC obstruction, abscess, empyema, pleural effusion, nodules • When in doubt, give contrast

8. General Chest CT • Data Sets: • 5 mm standard algorithm • 5 mm lung algorithm • 0.63 – 1.25 mm axial data • Sagittal & Coronal Reformats • 60 cc IV contrast @ 3 cc/sec • 30 Second Delay (Slightly arterial phase)

9. Calcified Granuloma

10. Pneumonia

11. Pneumocystis Pneumonia

12. Primary Lung Cancer

13. RUL/RML Adenocarcinoma with Mediastinal Adenopathy

14. Lung Abscess

15. Septic Emboli in IVDU with Pyopneumothorax

16. PE CTA • 60 cc IV contrast @ 5-6 cc/sec • Timed to Opacify the Pulmonary Arteries • Data sets: • 1.25 mm standard algorithm • 5 mm lung algorithm • Sagittal and coronal MIP reformats • Rotational MIP images at pulmonary trunks

17. Saddle Pulmonary Embolus with Infarction

18. Left Interlobar Pulmonary Artery Embolus

19. Left Main Pulmonary Artery Pulmonary Embolus

20. Chronic PE with Bronchial Collaterals

21. PE CTA is Not a “Better Chest CT” • Ideal exam if concern is for PE • Suboptimal for mediastinal pathology • Timing is early so makes detection of lymphadenopathy more difficult • Staging & comparison to prior chest CTs more difficult • Scan direction is from lung bases to apices • Thin collimation (1.25 vs 5 mm) • “Granier/Noisy” Image • Covers less of upper abdomen

22. Aortic Dissection CTA • Data sets: • Noncontrast chest CT • 5 mm standard algorithm • Contrast chest CTA • 2.5 mm standard algorithm • 1.25 mm standard algorithm • 5 mm lung algorithm • Sagittal and coronal MIP reformats • 80 cc IV contrast @ 5 cc/sec • Timed to opacify the ascending aorta • Can be extended into abdomen

23. Intramural Hematoma

24. Type A Aortic Dissection

25. Type B Aortic Dissection Curved Reformat

26. Intramural Hematoma -> Resolution -> Dissection

27. Opacification of Pulmonary Arteries vs Aorta • NSMC protocols are tailored to evaluate the pulmonary arteries OR aorta • Sometimes may be able to evaluate both, but often not • Variables: • Cardiac output • IV contrast dose • Bolus timing • Quality of IV, etc

28. Opacification of Pulmonary Artery vs Aorta

29. Triple Rule-out? • Much talked about CTA to rule out pulmonary embolus, aortic dissection and coronary occlusion • Currently not performing coronary CTA at NSMC

30. Minimizing Radiation • ALARA (As Low as Reasonably Achievable) Principle • Especially Important for Pediatric & Younger Adults • Multi-Detector CT (MDCT) • Thinner collimation/Overlapping images have better image quality but increase radiation dose • Technical innovations to help decrease radiation exposure include dose modulation (auto MA) • Higher radiation with increased number of passes/phases

31. Effective Dose • Measure of stochastic risk (carcinogenesis & hereditary risk) of non-uniform exposure to ionizing radiation • Measured in milliSieverts (mSv) • Allows comparison of the risk estimates associated with partial or whole-body radiation exposures • Incorporates different radiation sensitivities of the various organs in the body • Based on a tissue weighting factor (Chest = 0.019) • Average “Effective Dose" from natural background radiation is 3 mSv per year in the United States Food & Drug Administration

32. Effective doses in CT and radiographic examinations International Commission on Radiation Protection, Publication 87

33. Effective doses in CT and radiographic examinations Food & Drug Administration

34. Effective doses at Salem HospitalMay 24, 2009 – June 8, 2009 • Includes ED Patients, Inpatients & Outpatients • Effective Dose = Dose Line Product * Tissue Weighting Factor (0.019) •  5 Thoracic Aorta CTAs excluded due to concurrent abdominal scanning

35. Summary • Proper CT protocoling is important to optimally answer clinical question and to avoid excess radiation • Timing of contrast opacification is different for PE CTA vs Aortic Dissection CTA • PE CTA is not a “Super Chest CT” • Higher radiation dose with multiphase CT exams (ie Aortic Dissection CTA) • ALARA • Providing history helps us to help you

36. Questions? • If you don’t know which exam to order or how to order it, please ASK! • A Radiologist is in-house from 7:30 AM – 8 PM 7 days/week and on call through the night • Consultation: • Salem: x 4083 • Union: x 3538

37. References • British Journal of Radiology (2007) 80, e50-e53 • Schoepf, U. J. et al. Circulation 2004;109:e220-e221 • Circulation. 2003;107:e224-e225 • CHEST APRIL 2002 VOL. 121 NO. 4 1377-1378 • Eur Respir J 2003; 21:374-376 • AJR 2006; 187:W7-W14 • RadioGraphics 2004;24:1219-1238 • AJR 2006; 186:S414-S420 • RadioGraphics 2005;25:157-173 • International Commission on Radiation Protection, Abstract ICRP Publication 87 • www.FDA.gov • Hansell, D. M. et al. Radiology 2008;246:697-722\ • Radiology 2003;228:395-400 • Shim, S. S. et al. Am. J. Roentgenol. 2006;186:639-648 • Hagan, I. G. et al. Radiographics 2007;27:919-940 • Kinoshita, F. et al. Am. J. Roentgenol. 2006;187:926-932 • Frazier, A. A. et al. Radiographics 2008;28:883-899 • Hayter, R. G. et al. Radiology 2006;238:841-852 • Restrepo, C. S. et al. Radiographics 2007;27:1595-1610 • Radiographics. 2000;20:43-58 • Sharma, A. et al. Radiographics 2004;24:419-43

38. Questions Raised from Presentation to ED Staff • Possibility of a reliable double rule out? • Eliminating noncontrast exam for dissection exams? • Bring patient back in setting of dissection now that scanner is in the ED? • Reducing dose from dissection exam? • Use of 120 vs 140 kV • Routinely image/not image abdomen?

39. Other Impressions from Presentation to ED Staff • Generally happy with service of NSMC Radiology • Bennett Shamsai • Radiation figures got their attention • Looking for feedback • “How are we doing?” • “What are we doing wrong?” • Open to Communication