Steady-State Free-Precession Sequence for Differentiating Bronchogenic Carcinoma from Adjacent Atelectasis

Purpose: To evaluate the clinical usefulness of steady-state free-precession (SSFP) sequence for differentiating bronchogenic carcinoma from adjacent atelectasis. Methods: Ten patients with bronchogenic carcinoma and adjacent atelectasis underwent unenhanced magnetic resonance imaging (MRI). MRI examinations using the SSFP sequence, T2-weighted imaging (T2WI), and diffusionweighted imaging (DWI) (b=0, 1000 s/mm2) were performed on a 1.5-T scanner. Two independent observers evaluated the differentiating ability and image quality using 3-point scales. In addition, the relative contrast of carcinoma and atelectasis in the SSFP sequence and T2WI and apparent diffusion coefficient (ADC) of DWI were calculated. Statistical analyses were performed using the t-test, Friedman test, Wilcoxon test and analysis of variance. Results: The SSFP sequence showed significantly higher differentiating ability than T2WI (P=0.004) and significantly better image quality than T2WI (P<0.001) and DWI (P=0.005). There was a significant difference between the relative contrasts and the ADC values of carcinoma and atelectasis on all sequences (SSFP sequence, P=0.034; T2WI, P=0.010 and ADC, P<0.001). Conclusion: The SSFP sequence has the advantages of short acquisition times, which avoid motion artifacts, and relatively good contrast, which provides detailed anatomical information. It can be considered as a useful modality for differentiating bronchogenic carcinoma from adjacent atelectasis.