Title
Comparison of multi-detector CT venography and venous sonography for detecting lower limb deep venous thrombosis in patients with suspected pulmonary embolism
Date of Award
6-1-2010
Document Type
Dissertation
Degree Name
Master of Medicine (MMed)
Department
Imaging and Diagnostic Radiology (East Africa)
Abstract
Objective: This was a prospective analytic study that aimed to compare the agreement between CT pulmonary angiography (CTPA/CTV) and ultrasonography (US) for diagnosis of thromboembolic disease and determine the sensitivity, specificity, positive and negative predictive values of the 2 tests using the presence of thromboembolic disease as a reference standard.
Methods: 76 consecutive patients who were referred for CTPA at the Radiology department of Aga Khan University Hospital over an 8 month period between December 2008 and July 2009 were included in the study. All the patients underwent combined CTPA/CTV according to the usual departmental protocol. They subsequently had bilateral lower limb duplex US within 24 hours of the CTPA/CTV study. Results for the presence or absence of DVT were analyzed for both CTV and US. Presence of thromboembolic disease was defined by a composite reference standard and this was used to determine the sensitivity, specificity, positive and negative predictive values for both tests.
Results: 73 patients were included in the final analysis. The 2 imaging tests had similar results in 62 (84.93%) patients; CTV was positive and US was negative in 7 (9.6%) patients, while CTV was negative and US was positive in 4 (5.5%) patients. There was a moderate level of agreement (k= 0.528) between CTV and US for detection of DVT. CTV had a much higher sensitivity (94.1%), specificity (100%), PPV (100%), NPV (98.2%) compared to US (58.9%, 94.6%, 76.9%, 88.3% respectively) when the presence of thromboembolic disease was used as a reference standard.
Conclusion: CTV has higher sensitivity, specificity, positive and negative predictive values for detection of asymptomatic DVT compared to US when the presence of venous thromboembolic disease is used as a reference standard. Therefore, in patients suspected to have PE, CTV can be used to detect DVT without an additional duplex US examination.
Recommended Citation
Wanjohi, R. (2010). Comparison of multi-detector CT venography and venous sonography for detecting lower limb deep venous thrombosis in patients with suspected pulmonary embolism (Unpublished master's dissertation). .