Arjun Nair MBCHB, FRCR, Presenter: Nothing to Disclose

Praveen Pissay Gopala Rao MBBS, FRCR, Abstract Co-Author: Nothing to Disclose

Dhruv Patel MBBS, BSc, Abstract Co-Author: Nothing to Disclose

Katherine L. Downey MBBS, BSc, Abstract Co-Author: Nothing to Disclose

Brendan P. A. Madden MBBCh, MD, Abstract Co-Author: Nothing to Disclose

Ioannis Vlahos MBBS, Abstract Co-Author: Researcher, Siemens AG Consultant, Siemens AG Consultant, General Electric Company Consultant, Medicsight, Inc

To evaluate the “carina cross-over” (CCO) sign, a postulated new morphological criterion for the CT diagnosis of PH in a large population with suspected PH and right heart catheter (RHC) corroboration. To determine: 1) its relationship to pulmonary artery pressure (mPAP) and 2) its diagnostic performance for the PH diagnosis, measured against the CT metric of main pulmonary artery diameter (PA)≥3cm.

161 consecutive patients who underwent CTPA (64 x0.6mm, 120kVp, mAs 160-310) and RHC for suspected PH were retrospectively evaluated. Standardized RHC and axial PA measurements were recorded. CCO was defined as positive when the right pulmonary artery had already crossed anterior to the carina, on the most cephalad axial 2.5mm section on which the carinal division was visible. To allow for differences in determining the carinal level two thoracic radiologists evaluated by consensus the presence of CCO on standardized lung (CCO-L) and mediastinal (CCO-M) windows as well as a more stringent criterion of at least 1 cm cross-over on lung windows (CCO-1). Diagnostic performance of CCO measures was compared to mPAP and PA size ≥3cm criterion.

107 patients had mPAP>=25 defining PH. The mean mPAP of patients with a positive CCO-L, CCO-M and CCO-1 was higher than in patients without the sign (34 v 29, 33 v 28, 35 v 29mmHg, Mann-Whitney U p=0.000-0.003). CCO-L and CCO-1 had higher specificity (87, 91%) and positive predictive values (PPV) (89, 90%) than PA≥3cm (specificity 83%, PPV 88%), but with diminished sensitivity (51, 43% respectively, v 62%). In contrast, CCO-M provided a comparable sensitivity (64%) but a lower specificity (67%) and PPV (79%). In patients with any CCO sign and a PA≥3cm specificity was significantly increased. The combination of either a positive CCO-L or CCO-1 and a PA≥3cm resulted in a 100% specificity and PPV.        

The “carina cross-over sign”, is a newly proposed highly specific morphological criterion for the CT diagnosis of PH present in a significant proportion of PH patients. In this large RHC corroborated group the combination of lung window-determined cross-over with the established criterion of an enlarged PA resulted in 100% specificity and PPV.

The new highly specific morphological sign of right pulmonary artery “carina cross-over” is additive to the established relatively non-specific quantitative PA measures for the CT diagnosis of PH.

Nair, A, Pissay Gopala Rao, P, Patel, D, Downey, K, Madden, B, Vlahos, I, The “Carina Crossover Sign”: Evaluation of a New Proposed Morphological Criterion for the CT Determination of Pulmonary Hypertension (PH).  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11012277.html