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Non-small cell lung cancer: detection of early response to chemotherapy by using contrast-enhanced dynamic and diffusion-weighted MR imaging.

PURPOSE
To evaluate the ability of dynamic contrast material-enhanced and diffusion-weighted (DW) magnetic resonance (MR) imaging to help detect early response to chemotherapy in patients with non-small cell lung cancer (NSCLC).


MATERIALS AND METHODS
This study was approved by the institutional review board, and written informed consent was obtained from all subjects. Twenty-eight patients with stage IIIB or IV NSCLC (17 women, 11 men; mean age, 64.8 years) who underwent chemotherapy were enrolled. All patients underwent MR imaging before and after the first course of chemotherapy. The time to peak enhancement, maximum enhancement ratio, and washout ratio were determined from the time-signal intensity curves of dynamic contrast-enhanced MR images. The apparent diffusion coefficient (ADC) of each lung carcinoma was calculated from DW MR images. The responses of these parameters to the first course of chemotherapy and the pretreatment ADC itself were compared with final tumor size reduction by using the Pearson correlation coefficient. Kaplan-Meier curves of progression-free survival and overall survival were generated, and comparisons between the group with a good response of the significant parameter (upper 50th percentile) and that with a poor response of the significant parameter (lower 50th percentile) were performed by using a two-sided log-rank test.


RESULTS
Significant correlation was found only between early ADC change and final tumor size reduction rate (r(2) = 0.41, P = .00025). The median progression-free survival for the group with a good increase in ADC was 12.1 months, and that for the group with a stable or decreased ADC was 6.67 months (P = .021), while median overall survival was 22.4 and 12.3 months, respectively (P = .048).


CONCLUSION
ADC seems to be a promising tool for monitoring the early response to or predicting prognosis after chemotherapy of NSCLC.