Does multi-detector row CT pulmonary angiography reduce the incremental value of indirect CT venography compared with single-detector row CT pulmonary angiography?

Purpose: To compare retrospectively the incremental value of indirect computed tomographic (CT) venography performed after multi - detector row CT pulmonary angiography and single - detector row CT pulmonary angiography for the diagnosis of venous thromboembolism (VTE). Materials and Methods: The institutional ethics committee approved this study; informed consent was not required. The authors retrospectively reviewed results of 1100 combined single - detector row CT pulmonary angiographic and indirect CT venographic examinations (542 men, 558 women; mean age, 61 years +/- 17 [standard deviation]) (group 1) and 308 combined multi - detector row CT pulmonary angiographic and indirect CT venographic examinations (150 men, 158 women; mean age, 62 years +/- 18) (group 2), performed in 1408 patients suspected of having pulmonary embolism (PE). Frequency of deep venous thrombosis (DVT), PE, and VTE, and the incremental value of indirect CT venography were recorded in both groups. Data were compared by means of the Student t test for continuous data and z statistics for independent proportions. Results: VTE, PE, and DVT were found in 23.3% (n = 256), 19.9% (n = 219), and 18.3% (n = 201) of the 1100 patients in group 1, respectively, and in 23.7% (n = 73), 17.2% (n = 53), and 18.8% (n = 58) of the 308 patients in group 2, respectively (P values ranging from .273 to .876). The incremental value of indirect CT venography was 14.4% (37 of 256 patients) in group 1 and 27.4% (20 of 73 patients) in group 2. Conclusion: Despite potential improved accuracy of multi-detector row CT pulmonary angiography for the diagnosis of PE, the addition of indirect CT venography increased the diagnosis of VTE in 27.4% of patients.