Audit of CT Pulmonary Angiogram in suspected pulmonary embolism patients

Transcription

1 Audit of CT Pulmonary Angiogram in suspected pulmonary embolism patients Poster No.: C-2511 Congress: ECR 2012 Type: Scientific Exhibit Authors: N. D. Gupta, M. K. Heir, P. Bradding; Leicester/UK Keywords: Respiratory system, Lung, Pulmonary vessels, CT-Angiography, Nuclear medicine conventional, Diagnostic procedure, Contrast agent-intravenous, Embolism / Thrombosis DOI: /ecr2012/C-2511 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. Page 1 of 17

2 Purpose To audit the use of CT pulmonary angiogram (CTPA) Fig. 1 on page 3 in suspected pulmonary embolism (PE) patients. Also to compare the British Thoracic Society (BTS) and Wells clinical probability scores among these patients. Background: In patients with suspected PE Fig. 2 on page 3, making an assessment of clinical probability allows better interpretation of VQ scan results. In combination with D-dimer assay, it can substantially reduce the need for imaging in low and intermediate risk group patients. There are two clinical probability scores which are widely used in UK: BTS (Table 1) and Wells scores (Table 2). In patients with suspected PE (breathlessness and /or tachypnoea, with or without pleuritic chest pain and /or haemoptysis), is another diagnosis more likely? If not, Score=1 Major risk factors for PE? (Immobility, Major Surgery, Trauma, pregnancy/ postpartum, medical illness and venous thrombosis). If present score=1 Total BTS score High risk=2, Intermediate risk=1 and Low risk =0 Table 1: BTS Clinical Probability Score DVT (yes=3) PE likely (yes=3) HR>100 (yes=1.5) Immobilised for >3 days/ surgery <4weeks (yes=1.5) Previous PE/DVT (yes=1.5) Haemoptysis (yes=1) Malignancy (yes=1) Total Wells Score High risk =>6, Intermediate risk= 2-6, Low risk =<2 Table 2: Wells clinical probability score Page 2 of 17

3 Images for this section: Fig. 1: CT Pulmonary Angiogram Page 3 of 17

4 Fig. 2: Pulmonary Embolism: Pathway of Embolism to heart and lungs Page 4 of 17

5 Methods and Materials This was a retrospective audit looking at recent 75 CTPA's in BTS & Wells scores were collected from case notes and CTPA results from the radiology database. Data was analysed using Microsoft Excel Standards: BTS guidelines on the management of PE (2003). Criteria for measuring D-dimers: They should only be requested in patients with low or intermediate probability. A negative D-dimer in this group rules out PE and no further investigations are required. Patients with positive D-dimer will need to be further investigated. Chest X-ray: Fig. 3 on page 5 All patients suspected of acute PE should have a CXR prior to CTPA or VQ Scan. VQ Scan: Fig. 4 on page 6 Indications: When facilities are available on site and Chest X-ray (CXR) is normal, VQ scan can be considered in high risk group patients without any significant cardiopulmonary disease. Non-diagnostic results will need to be followed up by further imaging (CTPA). The report is analysed with the clinical probability scores. 1) Normal scan= no PE 2) Scan + clinical probability both low = no PE 3) Scan + clinical probability both high = PE present 4) any other = needs CTPA CTPA: Fig. 5 on page 7 Fig. 6 on page 8 It is the first line of investigation in massive PE. In non-massive PE, it is the investigation of choice in patients with abnormal CXR and/or significant cardiopulmonary illness. Images for this section: Page 5 of 17

6 Fig. 3: Chest X-ray in acute PE. Page 6 of 17

7 Fig. 4: VQ scan showing perfusion defect. Page 7 of 17

8 Fig. 5: Computed tomographic (CT) pulmonary angiography of acute pulmonary embolism (PE). Four-detector row CT scan of: a) segmental acute PE without right-heart compromise; b) acute PE with mildly dilated right-sided heart chambers, indicating acute cor pulmonale; and c) multi-slice image of a central PE, or so-called saddle thrombus. d, e) Sixteen-detector scan with three-dimensional reconstruction visualising the extent of the thromboembolic process. d) and e) Fig. 6: 3D CT reconstruction showing PE Page 8 of 17

9 Results Based on guidelines: CTPA was the most appropriate imaging modality in 50 out of 75 patients (66.7%). 24 patients were suitable for VQ scanning (33.3%) but had CTPA instead. There was insufficient data in 1 patient. Fig. 7 on page 9 55 patients had d-dimer measured, but only 35 were appropriate. Fig. 8 on page out of 67 patients' chest X-ray were abnormal. Chest X-ray was not performed in 8 patients. Fig. 9 on page 11 Clinical probability scores using BTS were 18, 42, 15 and for Wells 6, 32 and 37 for high, intermediate and low risk groups respectively. Fig. 10 on page patients were found to have PE. CTPA provided an alternative diagnosis in another 37 patients which is an advantage over VQ scanning. Fig. 11 on page 13 Among patients with proven PE, there were 3, 5 & 2 in BTS and 1, 4 and 5 in Wells high, intermediate and low risk groups respectively. Fig. 12 on page 14 Images for this section: Page 9 of 17

10 Fig. 7: Imaging Modality: CTPA & VQ scan Page 10 of 17

11 Fig. 8: d-dimer among suspected PE patients Page 11 of 17

12 Fig. 9: Chest X-ray in suspected PE patients. Page 12 of 17

13 Fig. 10: Clinical probability scores among suspected PE patients. Page 13 of 17

14 Fig. 11: Final diagnosis among suspected PE patients. Page 14 of 17

15 Fig. 12: Clinical probability scores among confirmed PE patients. Page 15 of 17

16 Conclusion Conclusion: If clinical guidelines were followed, 33.3% of patients would have had a VQ scan rather than CTPA. However, CTPA identifies an alternative diagnosis in 50% of subjects which is potentially advantageous. D-dimer still being requested in high probability cases. CXR not being done in 10.6% of patients prior to CTPA/VQ. In this audit, BTS scores were a better predictor than Wells for identifying positive PE patients. Discussion: Chest radiography is essential in the investigation of suspected PE. In the PIOPED 4 study, only 12% of patients had normal chest radiographs. In our audit, 46% of the CXR were normal. It is important to perform CXR so as to exclude diagnoses that clinically 4 mimic PE and it also aids in the interpretation of VQ scan. When selective VQ scanning is used, only a small number of patients (13%) go on to 3 need CTPA as well. In our audit, there were only 3 patients who had VQ scan initially and subsequently had CTPA. Compared with isotope scanning, CTPA is 2 a) quicker to perform, b) rarely needs to be followed by other imaging, c) may provide the correct diagnosis when PE has been excluded d) is now available in most hospitals and e) easier to arrange urgently out of hours. Our audit supports the above advantages of CTPA as this provided an alternative diagnosis in 50% of patients. Although many clinicians and radiologists recognise that CTPA should be the preferred initial imaging modality in suspected PE, current resources make this impracticable. References The imaging of suspected pulmonary emboli - UHL Guidelines, Dec 2007 British Thoracic Society Guidelines for the Management of Acute Pulmonary Embolism; Thorax 2003;58: Prologo JD, Glauser J. Variable diagnostic approach to suspected pulmonary embolism in the ED of a major academic tertiary care center. Am J Emerg Med 2002;20:5-9. Page 16 of 17

17 4. Worsley DF, Alavi A, Aronchick JM, Chen JT, Greenspan RH, Ravin CE. Chest radiographic findings in patients with acute pulmonary embolism: observation from the PIOPED study. Radiology Oct;189(1): Personal Information Dr. Nuthan Devi Gupta Department of Respiratory Medicine, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Groby Road, Leicester, LE3 9QP, United Kingdom Dr. Mandip Heir Department of Radiology, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Groby Road, Leicester, LE3 9QP, United Kingdom Prof. Peter Bradding Department of Respiratory Medicine, Glenfield Hospital, University Hospitals of Leicester NHS Trust, Groby Road, Leicester, LE3 9QP, United Kingdom Page 17 of 17