Douglas G. W. Fraser, MRCP Alan R. Moody, FRCR Ian R. Davidson, FRCR Anne L. Martel, PhD Paul S. Morgan, PhD Index terms: Magnetic resonance (MR), image processing Veins, extremities, 938.751, 988.751 Veins, MR, 938.12942, 988.12942 Veins, thrombosis, 938.751, 988.751 Published online before print 10.1148/radiol.2263012205 Radiology 2003; 226:812– 820 Abbreviations: IVC = inferior vena cava DVT = deep venous thrombosis MIP = maximum intensity projection SFV = superficial femoral vein 3D = three-dimensional VESPA = venous enhanced subtracted peak arterial 1 From the Departments of Academic Radiology (D.G.W.F., A.R.M., P.S.M.), Radiology (I.R.D.), and Medical Phys- ics (A.L.M.), Queen’s Medical Centre, Nottingham, England. Received Janu- ary 28, 2002; revision requested March 13; revision received June 12; ac- cepted July 25. Supported by grant RB2305 from the British Heart Founda- tion. Address correspondence to A.R.M., Department of Medical Imag- ing, Sunnybrook and Women’s Health Sciences Centre, 2075 Bayview Ave, To- ronto M4N 3M5, Ontario, Canada (e- mail: alan.moody@swchsc.on.ca). See also the editorial by Prince and Sostman in this issue. Author contributions: Guarantors of integrity of entire study, D.G.W.F., A.R.M.; study con- cepts, D.G.W.F., A.R.M., A.L.M.; study design, D.G.W.F., A.R.M.; literature research, D.G.W.F.; clinical studies, D.G.W.F., A.R.M.; experimental stud- ies, P.S.M., A.R.M.; data acquisition, D.G.W.F., A.R.M., P.S.M.; data analysis/ interpretation, all authors; statistical analysis, D.G.W.F.; manuscript prepara- tion, D.G.W.F.; manuscript definition of intellectual content, D.G.W.F., A.R.M., I.R.D.; manuscript editing, D.G.W.F., A.R.M.; manuscript revision/review and final version approval, all authors. © RSNA, 2003 Deep Venous Thrombosis: Diagnosis by Using Venous Enhanced Subtracted Peak Arterial MR Venography versus Conventional Venography 1 PURPOSE: To assess diagnostic accuracy and interobserver variability at venous enhanced subtracted peak arterial (VESPA) magnetic resonance (MR) venography compared with those at conventional venography for the diagnosis of femoral and iliac deep venous thrombosis (DVT). MATERIALS AND METHODS: A single anteroposterior maximum intensity projec- tion (MIP) venogram of the femoral and iliac veins was constructed by using VESPA MR venography in 55 symptomatic patients suspected of having lower limb DVT. All patients also underwent conventional venography, results of which were used as the standard of reference. VESPA MR venograms were interpreted by two independent reviewers (reviewers A and B) who were unaware of other results. Sensitivity and specificity of VESPA MR venography for the diagnosis of thrombus in the femoral and iliac veins were calculated. Interobserver variability was calculated for these observations by using weighted  with equally spaced weights for positive, nondi- agnostic, and negative studies. Nondiagnostic studies were reinterpreted separately by reviewer A on the basis of source data. RESULTS: Sensitivity of VESPA MR venography for the femoral veins (20 of 20) and iliac veins (seven of seven) was 100% for both reviewers. Specificity was 100% (39 of 39 for reviewer A, 40 of 40 for reviewer B) for the iliac veins and 97% (31 of 32) for the femoral veins for both reviewers. Segments in which the VESPA MR venograms were nondiagnostic were excluded from this analysis. Interobserver variability as calculated by using weighted  for positive, negative, and nondiag- nostic studies was 0.85 for femoral veins and 0.97 for iliac veins. Interpretation of the source data led to correct diagnosis in six of six cases in which the VESPA MR venograms were nondiagnostic. CONCLUSION: VESPA MR venography yielded MIP venograms that were highly accurate for the diagnosis of DVT in femoral and iliac veins. Interpretation of the studies was also highly reproducible. © RSNA, 2003 The multiplanar capabilities of magnetic resonance (MR) imaging make it well suited for imaging central veins. Time-of-flight MR techniques have been used most frequently; with these techniques, thrombosis within the inferior vena cava (IVC) and the iliac and femoropopliteal veins can be visualized with a high degree of accuracy (1– 6). However, image acquisition is slow with the time-of-flight technique, and images are susceptible to flow artifacts and saturation (7). To retain both high in-plane spatial resolution and sufficient field of view while keeping imaging times at an acceptable level, images are frequently acquired as a series of two-dimensional sections separated by gaps (1– 4). When images are acquired in this way, maximum intensity projection (MIP) algorithms and 812 R adiology