Lung cancer: differentiation of tumor, necrosis, and atelectasis by means of T1 and T2 values measured in vitro.

In vitro measurements of T1 and T2 values were performed in surgical specimens from 15 patients with lung cancer. Correlation between histologic results and measured values revealed that different pathologic tissues can be characterized by means of T1 and T2 values. The transverse magnetization decay curve of the lung tissue was multiexponential, which can be explained by two different relaxation times, fast T2 and slow T2. The signal intensity of pathologic lung tissues at different pulse sequences was simulated on a signal intensity gradient graph based on measured values of T1, fast T2, slow T2, and water content. The results showed that T2-weighted sequences were more valuable in discriminating viable lung cancer from necrotic tumor and collapsed lung lesions.