Diffusion-weighted magnetic resonance imaging in differentiating the invasiveness of small lung adenocarcinoma.

BACKGROUND

Magnetic resonance imaging (MRI) with several sequences may provide a valuable additional modality for evaluating the grade of invasiveness lesions. Diffusion-weighted magnetic resonance imaging (DWI) represents the biological characteristics of tissues.

PURPOSE

To retrospectively evaluate the usefulness of DWI for evaluating the invasiveness of small lung adenocarcinomas.

MATERIAL AND METHODS

From May 2005 to June 2008, 46 patients with lung adenocarcinomas measuring 2 cm or less across the greatest dimension underwent a preoperative MRI study followed by surgery at the Gunma Prefectural Cancer Center. Fourteen of the tumors were bronchioloalveolar carcinomas (so-called Noguchi's type A+B group), 26 were adenocarcinomas with mixed subtypes (type C group) and six were other histological subtypes of adenocarcinomas (type D+E+F group). The mean signal intensities of a lesion (DWI) and the spinal cord (SC) were analyzed in the region of interests (ROIs), and the mean DWI/SC ratio was then calculated with the value of DWI divided by the value of SC.

RESULTS

The calculated mean DWI/SC ratio for the lesions were as follows: 0.448±0.261 (mean±standard deviation [SD]) for type A+B group, 0.963±0.465 for type C group, and 0.816±0.291 for type D+E+F group. The mean DWI/SC ratio of type A+B group was significantly lower than that for the type C (P = 0.0005) or type D+E+F groups (P = 0.0117).

CONCLUSION

DWI may thus provide useful supplementary information before determining the surgical strategy, including a limited resection.