Yukihiro Nagatani MD, Presenter: Nothing to Disclose

Masashi Takahashi MD, Abstract Co-Author: Research Consultant, F. Hoffman-La Roche Ltd Research Consultant, Novartis AG

Norihisa Nitta MD, Abstract Co-Author: Nothing to Disclose

Akinaga Sonoda MD, PhD, Abstract Co-Author: Nothing to Disclose

Hideji Otani MD, Abstract Co-Author: Nothing to Disclose

Kiyoshi Murata MD, Abstract Co-Author: Nothing to Disclose

To retrospectively assess the correlation among both total cross-sectional area (CSA) of small pulmonary vessels on CT images, PAD in right main pulmonary artery (MPA) and systolic pulmonary artery pressure (PAP) estimated by trans-thoracic echocardiography (TTE).

Study group consisted of 43 patients who underwent both retrospectively ECG-gated 320-row CTA and low-dose chest CT, and in addition, TTE within 1 month. They were classified into 29 patients in Group A (systolic PAP) >30 mmHg) and 14 patients in Group B (systolic PAP <30 mmHg). Scan data was reconstructed at 10% increment between 0% and 90% of RR intervals. PAD at the cross section of right MPA was calculated as follows; PAD = 100 (maximal dimension – minimal dimension) / minimal dimension. The diameter of main pulmonary artery (DMPA) was measured at its widest position on the trans-axial CTA images at end-systolic phase. On the identical slice, the diameter of ascending aorta (DAA) was measured and ratio of DMPA to DAA (DMPA/DAA) was calculated. The percentage of total CSA of less than 5 mm2 for the total lung area (%CSA<5) in the three selected planes in the upper, middle and lower lung field as an index of pulmonary vascular alteration was calculated. These values were compared between 2 groups using t-test. The area under the receiver operating characteristic (ROC) curve and correlation with systolic PAP were obtained. Coefficients of correlation between %CSA<5 and PAD was also obtained.

Average value of PAD and %CSA<5 were different between 2 groups (PAD: 20.9 in group A versus 27.0 in goup B and %CSA<5: 0.71 in group A versus 0.82 in goup B). No significant diffierence was shown between 2 groups both in DMPA and DMPA/ DAA . systolic PAP had moderate negative correlation with %CSA<5 (r=-0.574, p<0.001) and with PAD (r=-0.549, p<0.001). Areas under ROC curve were quite similar in the 2 indices, as 0.771 in PAD and 0.773 in %CSA<5.  %CSA<5 correlated also positively with PAD (r=0.663, p<0.001).

%CSA may reflect PAD and both 2 indices can be a useful predictor of PAH.

Small pulmonary vascular alteration may be asscoiated with stiffness of central pulmonary artery, and both indices can be useful non-invasive predictors of PAH.

Nagatani, Y, Takahashi, M, Nitta, N, Sonoda, A, Otani, H, Murata, K, Quantitative Measurement of Small Pulmonary Vessels Area and Pulmonary Artery Distensibility (PAD) in Pulmonary Arterial Hypertension (PAH) Using Images Obtained with 320-Row Computed Tomography (CT).  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12028702.html