Epidermiology Early pulmonary embolism Sitang Nirattisaikul Faculty of Medicine, Prince of Songkla University 3 rd most common cause of cardiovascular death in the United States, following ischemic heart disease and stroke Incidence: 300,000-600,000 per year. Prevalence : 0.4% 12-14.8% of autopsy Radio Clin N Am 2010;48: 31 50 AJR 2011;196:497-515 Chest 1995;108:978-81 Pulmonary embolism Mortality 10-30% 80% within 30 min 90% within 2.5 hours Mortality 2% to 10% with timely diagnosis and treatment Risk factors Older age Hx of previous VTE Active cancer Surgery Prolonged bed rest Congenital or acquired thrombophilia Unprovoked or idiopathic PE : 30% AJR 2011; 196:497 515 Radiology 2006;239:563-75 Radio Clin N Am 2010;48: 31 50 Thailand Incidenct of VTE : 0.59% Most common risk factor : immobilization and active cancer Blood Coagul Fibrinolysis 2010;21:334-8 Clinical manifestations Dyspnea Pleuritic chest pain Classic triad Hemoptysis Cough Tachycardia Poor hemodynamic status No clinical Radio Clin N Am 2010;48: 31 50 1
Imaging modalities for diagnosis of PE CXR V/Q scan, SPECT : functional parameter changes CT angiography morphologic change Pulmonary angiography DVT Ultrasound What is the standard test? AJR 2011:196:497-515 Summary of Imaging Modalities Used in the Detection of PE Modality Sensitivity (%) Specificity (%) PPV(%) NPV(%) CXR 36 92 38 76 V/Q scintigraphy (planar) V/Q scintigraphy (SPECT) Pulmonary MDCTA Catheter angiography 76-98 85-93 96-100 83-92 83-97 91-98 96-100 86-89 92-96 94-100 87 88 MRA 57 75 AJR 2011; 196:497 515 Ventilation-Perfusion Scintigraphy Limitation inconclusive interpretations: 30-50% of patients have non-diagnostic scan necessitating further investigation inpatients and critically ill patients AJR 2011:196:497-515 Radiology 2008;246:941--6 SPECT compared with V/Q scintigraphy higher diagnostic : Nondiagnostic SPECT V/Q scans <3% Higher contrast resolution detect abnormalities at the subsegmental level and lung bases AJR 2011:196:497-515 J Nucl Med 2009; 50:1999 2007 Catheter Pulmonary Angiography Late 1960s: the reference standard Invasive: 2% morbidity 0.5% mortality Poor interobserver agreement in subsegmental branch AJR 2011:196:497-515 Circulation. 1992;85:462-468 Radiology 2000; 217:447 455 2
Pulmonary MR Angiography High technically inadequate longer examination times Limited access to MRI Limited detection of other diagnosis Contraindication implanted devices AJR 2011:196:497-515 RadioGraphics 2004; 24:1219 1238 Pulmonary CT Angiography Now the standard diagnostic test Advantage Rapid and widespread availability noninvasiveness and accuracy Definite diagnosis better than V/Q scintigraphy Diagnosis of other causes of chest pain RadioGraphics 2004; 24:1219 1238 Acta Radiologica 2012; 53: 39 43. AJR 2011:196:497-515 Early pulmonary embolism??? Early pulmonary embolism Small or subsegmental PE Incidental or unsuspected PE: asymptomatic 3
Early pulmonary embolism Small or subsegmental PE Incidental or unsuspected PE: asymptomatic Important??? Difficult diagnosis Small filling defect Limited clinical significance Accuracy modality, protocol Misdiagnosis False positive: Anticoagulant risk False negative : Recurrent PE or chronic pulmonary hypertension, further investigation Isolated subsegmental PE (ISSPE) Isolated subsegmental PE Modern diagnosis. It was not clinically relevant for live patients before the mid-1990 s. Arch intern Med 2006; 171:831-7 Isolated subsegmental PE Unique or multiple subsegmental vessels Controversial debate about the clinical significance of isolated subsegmental PE Asymptomatic Patient undergoing CT for other reasons. Autopsies Isolated subsegmental PE relatively low concomitant DVT rates 14% relatively less sensitive D-dimer test 76-90% Arch intern Med 2006; 171:831-7 AJR 2011:196, 497-515 4
Isolated subsegmental PE 4-7% of all CTPA studies: clinical suspected PE Proven pulmonary embolism: 7-24% = ISSPE What is the problem with subsegmental pulmonary embolism diagnosis? J Thorac Imaging 2012;27:304 314 Thrombosis Research 2010;126: e266 e270 Incidence and mortality of pulmonary embolism in the United States, 1993 2006 Arch intern Med 2006; 171:831-7 Rates of potential complications of anticoagulation treatment among US adults hospitalized with a pulmonary embolism, 1993 2006 Pulmonary MDCTA Sensitivity 90-100% Specificity 89-94% PIOPED II study The PPV for PE: 97%: a main or lobar a. 68%: segmental a. 25% :subsegmental a. Arch intern Med 2006; 171:831-7 AJR 2011:196, 497-515 5
A Comparison Between V/Q Lung Scintigraphy in SPECT Technique and Multislice Spiral CT A Comparison Between Angiography and CTA J Nucl Med 2004; 45:1501 1508 Contrast-enhanced CTA Oblique-sagittal multiplanar reformat. Circulation 2004;109:e220-e221 Circulation 2004;109:e220-e221 Volume-rendered 3D Isolated subsegmental PE Further investigation Treatment Circulation 2004;109:e220-e221 6
CTPA or V/Q scintigraphy Or Angiography Isolated subsegmental PE Precede recurrent larger PE and increase the risk of chronic pulmonary hypertension Usually treated with anticoagulation. No strong evidence to clearly support a treatment or nontreatment strategy Long term death rate in pulmonary embolism AJR 2006; 187:W7 W14 Long term recurrent rate 7
3 months outcomes Recurrent PE Mortality ISSPE 1.05% 0% Typical PE(untreat) 39% 26% Typical PE(treat) 8% 1.7% Negative CTA 1.4% 0.5% Diagnosis and Management of Isolated Subsegmental Pulmonary Embolism: Review and Assessment of the Options withhold treatment for subsegmental PE (1) good pulmonary respiratory reserve (2) no evidence of DVT on serial testing (3) Transient the major risk factor for PE (4) no history of central venous catheterization or atrial fibrillation (5) willingness to return for serial CUS. J Thorac Imaging 2012;27:304 314 Early pulmonary embolism Small or subsegmental PE Incidental or unsuspected PE: asymptomatic Incidental PE Increased reports in patients undergoing chest CT. Prevalence : 1.0 1.5% on routine CT Higher prevalence in inpatient: 4 5%. Incidental PE in cancer patient : 4% Associated with DVT 40-50% AJR 2011; 196:497 515 Thrombosis Research 2010;125:518-22 RadioGraphics, 24, 1219-1238 AJR 2005;184:264 267 8
Incidental PE Cancer patient : malignant brain tumors, and adenocarcinoma of the ovary, pancreas, colon, stomach, lung, and prostate Poor prognosis : a high recurrence rate and high mortality rate Incidental PE All had multiple emboli 53% central pulmonay artery 47% peripheral pulmonary artery Vasc Health Risk Manag. 2011; 7: 153 158. Thrombosis Research 2010;125:518-22 Incidental PE 25% identified at initial CT image interpretation. Missed emboli were typically solitary and involved smaller arteries. 56-year-old with pulmonary metastases from colon carcinoma AJR 2011; 196:497 515 AJR 2005;184:264 267 Further management Review the CT scans Compared other recent CT scans Reveals symptoms suggestive of PE Additional diagnostic testing D-dimer, US DVT, CT pulmonary angiography The degree of pulmonary artery opacification The pulmonary trunk or the left main pulmonary artery. good > 150 H satisfactory 100-150 H poor < 100 H complete or partial filling defect AJR 2005;184:264 267 9
Window setting Standard window sitting width, 400 H; level, 40 H Wider window setting width, 600 H; level, 100 150 H 70-year-old man with lung cancer misdiagnosis 3 months later AJR 2005;184:264 267 AJR 2005;184:264 267 Patients with PE and cancer LMWH for the first 3 to 6 months of long term anticoagulant therapy (Grade 1A). Subsequent anticoagulant therapy with VKA or LMWH indefinitely or until the cancer is resolved (Grade 1C). Unexpectedly asymptomatic PE The same initial and long-term anticoagulation as for comparable patients with symptomatic PE (Grade 1C). CT signs of small PE 10
Acute small PE Polo mint or donut sign Railway or trum track sign Lung infarct Chronic small PE Causes of Misdiagnosis of Pulmonary Embolism Technically inadequate CT angiograms due to motion artifacts or insufficient opacification of the pulmonary vessels 5 8%. European Heart Journal 2008; 29: 2276 315 Respiratory Motion Artifact: seagull sign Motion artifact False negative CTA 11
Flow-related Artifact Window Settings Image Noise False positive CTA Pulmonary Artery Catheter Flow-related Artifact 12
Streak Artifact Partial Volume Artifact Stair Step Artifact Partial Volume Averaging Effect in Lymph Nodes Vascular Bifurcation Misidentification of Veins 13
Mucus Plug Perivascular Edema Conclusion Early PE: small and difficult diagnosis Isolated subsegmental PE is ralatively benign prognosis No strong evidence to clearly support a treatment or nontreatment strategy But, increased risk of major bleeding. Incidental PE Greater attention, even if clinically unsuspected, particular in high risk group Thank you for your attention Sitrang_n@hotmail.com 14