Mateusz Piotr Kubak MD, Presenter: Nothing to Disclose

Arne Borthne MD, PhD, Abstract Co-Author: Nothing to Disclose

Peter M. Lauritzen MD, Abstract Co-Author: Nothing to Disclose

Espen Ruud, Abstract Co-Author: Nothing to Disclose

Haseem Ashraf MD, Abstract Co-Author: Nothing to Disclose

Improved spatial and temporal resolution CT pulmonary angiography (CTPA) allows accurate diagnosis of acute pulmonary embolism (APE). In low risk patients a d-dimer below the cut-off value of 0.5 mg/L may exclude APE, thereby eliminating the need for CTPA. Our purposes are to: 1) investigate the correlation of APE location and d-dimer levels, and 2) to optimize the cut off value of d-dimer while maintaining a high sensitivity and negative predictive value.

All 1053 patients with clinical suspicion of APE investigated with CTPA in our department in 2012 were eligible. Concurrent d-dimer values, required for inclusion were collected and CTPAs reviewed. The subjects were allocated to four groups based on diagnosis and APE location (0=no emboli, I= peripheral emboli, II= emboli in lobar arteries, III = emboli in pulmonary trunk or main pulmonary arteries). The optimal cut-off values of d-dimer in central and peripheral emboli were assessed.

Sufficient data were available for 822 subjects, while 229 lacked concurrent d-dimer and 2 were excluded due to low quality images. 53% females, mean age 64 years (range 9-99). 639 were allocated to group 0, 51 to group I, 51 to group II and 81 to group III. ROC (receiver operating characteristic) analysis revealed an area under the curve (AUC) of 0.78 for all APE (groups I, II and III). For central APE (group III) the AUC was 0.84. The optimal cut-off for all APE was 0.9 mg/L with a negative predictive value (NPV) of 97% and sensitivity of 97%. For central APE the cut-off was 1.4 mg/L with a NPV and sensitivity of 98% and 99% respectively. Significant correlation was found between the d-dimer values and the location of the APE in the selected subgroups (0: 2.4, I: 2.8, II: 4.2, III: 7.8) Spearmans rho: 0.43, p<0.01.

A D-dimer cut-off of 0.9 mg/L yielded a NPV and sensitivity of 97% for all APE. For central APE a d-dimer cut-off of 1.4 mg/L yielded a NPV and sensitivity > 98%. Higher d-dimer values significantly correlated with more centrally located APE.

Our findings may influence the approach to suspected acute pulmonary emboli, contribute to reduction of inappropriate CTPAs and aid priority of patients with central APE for expedient investigation.

Kubak, M, Borthne, A, Lauritzen, P, Ruud, E, Ashraf, H, CT Angiography: Correlation between D-dimer Values and the Location of Acute Pulmonary Embolism.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14010561.html