CTPA for Pulmonary Emboli: 2016 update

Transcription

1 2016 Annual Course CTPA for Pulmonary Emboli: 2016 update Olga R Brook, MD, FSCBTMR Beth Israel Deaconess Medical Center, Boston Beth Israel Deaconess Medical Center HarvardMedical School

2 Contents Technique Diagnosis and treatment of acute PE Pitfalls in PE diagnosis Incidental PE (over?)utilization and outcomes

3 Pulmonary emboli ~300,000 in US/year Incidence with age yrs: 1.3 : yrs: 2.8 : rd cause of CV mortality 2% in normotensive patients without evidence of RV dysfunction 30% with shock 65% in patients with cardiac arrest at presentation

4 TECHNIQUE

5 Technique at BIDMC 4 ml/sec with Omnipaque 350 Trigger at LA with bolus tracking Shallow inspiration Noise Index ~16 Scan acquired: 0.5mm Reconstructions: 2.5 & 1.25 mm axials 5mm coronal and sagittals 15 mm rt and lt obliques BMI kvp IV contrast (cc) < > LA threshold (HU)

6 Prospective, randomized study 2 groups of 30 pts 200 ma 80 ml IV contrast Effective dose: 1.37 vs 2.44 msv ( 44%) kVp Heyer CM et al. Radiology 2007; 245(2):

7 Recirculation technique 150 ml at 2 ml/sec Scan delay sec Slow rates for ports and small vessel injections 412 HU

8 Gadolinium: mmol/kg at 6 ml/sec 15 ml saline flush kvp Not used anymore due to NSF Remy-Jardin M et al. Radiology 2006

9 Dual Energy CT for Iodine distribution Thieme SF et al AJR 2009

10 CTPA in pregnant women No C- Oral barium for fetal shield Reduced range (arch to dome) No respiratory suspension 100 ml at 4 ml/sec Delay: 15 sec (no trigger) 100 kvp mas Effective dose ~ 1.5 msv Litmanovich D et al JCAT 2009 Shaefer-Procop C et al Europ Radiol 2008

11 CT Venography Selective Use High risk patients with signs of DVT or prior DVT Severely ill or ICU patients Recent surgery in pelvis Cast or extremity surgery Can not do US Goodman LR et al AJR 2009

12 DIAGNOSIS AND TREATMENT OF PULMONARY EMBOLI

13 Occlusion or filling defect Branching Multiple more than 1 level Vessel enlargement Polo-mint or railway track High attenuation (C-) Ancillary Wedge shape opacities Oligemia Acute PE Wittram C et al. RadioGraphics 2004 Patel S & Kazerooni EA. AJR 2005

14 Segmental PE Subsegmental PE Polo mint

15 Central lucency Pulmonary infarction 98% specificity & 46% sensitivity Revel MP et al Radiology 2007

16 Ground Glass Opacity vs Oligemia Acute PE induces GGO in nonobstructed lung zones Redistribution of blood flow Oligemia in obstructed areas Pulmonary edema with GGO in non-obstructed Thoma P et al Radiology 2009

17 Acute RV strain RV dilatation (RV/LV > 0.9) Level of MV and TV From inner to inner wall Deviation of IV septum to left / straightening X 3.6 rate admission to ICU Hepatic vein reflux

18 Clot burden is not predictive of short or long-term survival Clot burden Central clot location is predictive of worse outcome Furlan A et al Radiology 2012 Morris MF et al AJR 2012 Vedovati MC et al Chest 2012

19 European Society of Cardiology Model of PE severity Torbicki et al. Eur Heart J 2008

20 Thrombectomy & Thrombolysis Mainstay of PE tx is systemic anticoagulation CV collapse However risk of hemorrhagic stroke > 2% New (old) frontiers - catheter directed tx Percutaneous aspiration thrombectomy Flow directed thrombolysis US-accelerated catheter-directed thrombolysis (EKOS) Results: improvement in RV function w/out major bleeding events Bayiz H et al Heart Lung Circ 2015 Gaba RC et al AJR 2014 Piazza et al JACC Cardiovasc Interv Bagla et al JVIR 2015

21 PITFALLS

22 PE pitfalls Technical Poor bolus Resp & Cardiac motion Noisy images (large pts) Streak artifacts (lines, tubes, arms) Beam hardening (SVC w dense contrast) Interpretation Lymph nodes Pulmonary vein Mucoid impaction in bronchi Partial volume averaging Tumor emboli Wittram C, et al. RadioGraphics 2004 Patel S & Kazerooni EA. AJR 2005

23 Misdiagnosis of PE Hutchinson BD et al AJR :2,

24 Deep inspiration Shallow inspiration Up to 7% of patients Valsava Chest pain: Ao & PA

25 Deep inspiration immediately before acquisition intrathoracic pressure unopacified blood enters the RA from IVC filling defect in PA Transient interruption of contrast!

26 Recognize lack of opacifications of multiple vessels at the same level bilaterally, no vessel dilatation Unopacified blood in RH followed by LH Prevent by shallow inspiration prior to scanning

27 Poor bolus, large patient, noisy image Mucoid impaction

28 INCIDENTAL SUB-SEGMENTAL PE

29 Significance of incidental PE 1.5% of outpatients have incidental PEs 70% of autopsies show PE Unknown Systemic circulation protected by: Physiologic filter of pulmonary capillary bed Endogenous thrombolysis Mortality did not decrease with in dx

30 205,198 pts after TKR and THR in 178 hospitals 3,647 (rate 0-6%) CTPAs Positive PE rate 12.3% (median 9.1%) Similar with varying CTPA utilization Kumamaru KK et al, Radiology 2016

31 Diagnosis of PE and PE mortality Risks: CTPA: radiation and contrast anticoagulation Burge AJ, Freeman KD, Klapper PJ, Haramati LB. Increased diagnosis of pulmonary embolism without a corresponding decline in mortality during the CT era. Clin Radiol Apr;63(4):381-6.

32 Treatment of incidental PE Treat Inadequate cardiopulmonary reserve Acute DVT Recurrent small PE Withhold No or few risk factors for PE Transient risks (surgery) Other CV disease can explain symptoms Negative D-Dimer Risk of anticoagulation is high Goodman LR. Radiology 2005

33 ? Overutilization year trend of CTPAs at BIDMC CTPAs CTs x10 PE: Life threatening CTPA: High accuracy with ease in performing and interpreting Plateau in CTPA use Plateau in positive PE rate: 9-12%

34 When CTPA is appropriate? Mamlouk et al. Radiology 2010

35 Wells Clinical Criteria for PE VARIABLE Points Clinical DVT 3 No alternative Dx 3 HR > 100 bpm 1.5 Imobil/Surg 4 wks 1.5 Previous DVT/PE 1.5 Hemoptysis 1 Cancer 1 Wells PS et al Annals Intern Med 2001 PROBABILITY Points Low < 2 Intermediate 2-6 High > 6 D-dimer for low & intermediate risk CTPA for high risk

36 Pulmonary Embolism Rule-out Criteria If PE is considered, but clinically low risk AND: <50 years of age pulse <100 bpm SaO2 95% no hemoptysis no estrogen use no history of surgery/trauma within 4 weeks, no prior PE/DVT no present signs of DVT PE can be safely ruled out. Patient does not require further workup!

37 D-dimer Excludes PE in patients with low to moderate pretest probability for VTE sensitivity 95% specificity 55% Not helpful with high probability High levels in: Prior DVT or PE >80 years old >20 weeks pregnancy Cancer and hospitalized patients Sadigh, Kelly, Cronin AJR 2011;196(3):

38 Use of appropriateness criteria Quarterly feedback reporting use of Wells criteria improved adherence Mandatory requirement for use in ordering improved appropriate ordering Appropriate use of CT (Overuse 14% 10%) Did not change positive rate for PE (~14%) Did not change rate of CT utilization Raja AS et al AJR 2015 Getting GK et al AJR 2016

39 Conclusion Massive and submassive PE are life threatening and need to be robustly diagnosed for appropriate treatment BUT CTPA is a very sensitive test that detects way more than we need to know We need to convert from diagnosis to improving outcomes Entities should not be multiplied unnecessarily

40 Thank you! Dr Vassilius Raptopoulos Dr Diana Litmanovich Carol Wilcox, RT