Role of first-pass perfusion ct in differentiation of centrally located lung carcinomas from distal atelectasis

In our study we aimed to differentiate postobstructive consolidation from lung cancer by means of first-pass perfusion CT in centrally located malignancies.We studied 20 patients (18 male and 2 female) diagnosed as lung cancer including untreated central masses with distal postobstructive atelectasis.In order to localize the slice position showing appropriate mass-consolidation area to be included in the contrast-enhanced dynamic imaging, firstly, scout and baseline acquisition without contrast media was performed on the patients, followed by dynamic acquisition after intravenous contrast media injection. Three different ROIs were placed both on the central mass avoiding from the peripheral regions , as possible and the peripheral locations of distal consolidation using dynamic contrast-enhanced images. BV, BF, TTP and MTT perfusion parameters were automatically calculated in the ROI locations. We were able to differentiate the central masses from distal consolidations by means of statistically differences in first-pass BV and BF parameters between masses and distal consolidation. The mean values of parameters which were calculated in the masses and consolidations were BV:7.69±4.28, BF: 48.87±25.54, TTP: 27.94±7.32, MTT: 9.56±3.47 and BV: 11.83±5.34, BF: 78.75±39.41, TTP: 29.72±6.05, MTT: 11.44±4.93, respectively.We concluded that first-pass perfusion CT may be applied as a functional imaging method to differentiate central lung cancer from distal consolidation and this technique may be used in reducing the target cancer volume in patients who are candidates for radiation therapy.Key Words: Perfusion Computed Tomography (CT); First-Pass; Postobstructive Consolidation; Central Lung Carcinoma