Our aim in this study was to differentiate postobstructive consolidation from lung cancer by means of first-pass perfusion CT in centrally located malignancies. We studied 20 patients (18 males and 2 females) diagnosed as lung cancer with untreated central masses and distal postobstructive atelectasis. In order to localize the slice position showing the appropriate mass-consolidation area to be included in contrast-enhanced dynamic imaging, we first performed scout and baseline acquisition without contrast media, followed by dynamic acquisition after intravenous contrast media injection. Three different ROIs were placed on the central mass while avoiding the peripheral regions as much as possible and on the peripheral locations of distal consolidation using dynamic contrast-enhanced images. The 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 statistical differences in the first-pass BV and BF parameters between the mass and distal consolidation areas. The mean values of parameters that were calculated in the mass and consolidation areas were BV:7.69±4.28 ml/100g, BF:48.87±25.54 ml/100g/min, TTP:27.94±7.32 sec., MTT:9.56±3.47 sec. and BV:11.83±5.34 ml/100g, BF:78.75±39.41 ml/100g/min, TTP:29.72±6.05 sec., MTT:11.44±4.93 sec., respectively. We concluded that first-pass perfusion CT may be used as a functional imaging method to differentiate central lung cancer from distal consolidation and could be useful 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
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