Diffusion Weighted Magnetic Resonance Imaging for the Characterization of Solitary Pulmonary Lesions

Abstract

Background: We evaluated the differential diagnosis of solitary pulmonary lesions on magnetic resonance imaging. Aims: To investigate the value of diffusion weighted imaging on the differential diagnosis of solitary pulmonary lesions. Study Design: Randomized prospective study. Methods: This prospective study included 48 solitary pulmonary nodules and masses (18 benign, 30 malignant). Single shot echo planar spin echo diffusion weighted imaging (DWI) was performed with two b factors (0 and 1000 s/mm2). Apparent diffusion coefficients (ADCs) were calculated. On diffusion weighted (DW) trace images, the signal intensities (SI) of the lesions were visually compared to the SI of the thoracic spinal cord using a 5-point scale: 1: hypointense, 2: moderately hypointense, 3: isointense, 4: moderately hyperintense, 5: significantly hyperintense. For the quantitative evaluation, the lesion to thoracic spinal signal intensity ratios and the ADCs of the lesions were compared between groups. Results: On visual evaluation, taking the density of the spinal cord as a reference, most benign lesions were found to be hypointense, while most of the malignant lesions were evaluated as hyperintense on DWI with a b factor of 1000 s/mm2. In contrast, on T2 weighted images, it was seen that the distinction of malignant lesions from benign lesions was not statistically significant. The ADCs of the malignant lesions were significantly lower than those of benign lesions (mean ADC was 2.02×10-3 mm2/s for malignant lesions, and 1.195×10-3±0.3 mm2/s for benign lesions). Setting the cut-off value at 1.5×10-3, ADC had a sensitivity of 86.7% and a specificity of 88.9% for the differentiation of benign lesions from malignant lesions. Conclusion: DWI may aid in the differential diagnosis of solitary pulmonary lesions.

Keywords

• b factor, diffusion weighted magnetic resonance imaging, lung cancer, solitary pulmonary nodule

References

1. 1. Swensen SJ, Brown LR, Colby TV, Weaver AL. Pulmonary nodules: CT evaluation of enhancement with iodinated contrast material. Radiology 1995;194:393-8. [CrossRef]
2. 2. Le Bihan D, Turner R, Douek P, Patronas N. Diffusion MR imaging: clinical applications. AJR Am J Roentgenol 1992;159:591-9. [CrossRef]
3. 3. Ozsunar Y, Sorensen AG. Diffusion- and perfusion-weighted magnetic resonance imaging in human acute ischemic stroke: technica considerations. Top Magn Reson Imaging 2000;11: 259-72. [CrossRef]
4. 4. Hakyemez B, Yildiz H, Ergin N, Uysal S, Parlak M. FLAIR and diffusion weighted MR imaging in differentiating epidermoid cysts from arachnoid cysts. Tani Girisim Radyol 2003;9:418-26.
5. 5. Wang J, Takashima S, Takayama F, Kawakami S, Saito A, Matsushita T, et al. Head and neck lesions: characterization with diffusion-weighted echo-planar MR imaging. Radiology 2001;220:621-30. [CrossRef]
6. 6. Tanner SF, Ramenghi LA, Ridgway JP, Berry E, Saysell MA, Martinez D, et al. Quantitative comparison of intra brain diffusion in adults and preterm and term neonate and infants. AJR Am J Roentgenol 2000;174:1643-9. [CrossRef]
7. 7. Naganawa S, Kawai H, Fukatsu H, Sakurai Y, Aoki I, Miura S, et al. Diffusion-weighted imaging of the liver: technical challenges and prospects for the future. Magn Reson Med Sci 2005;4: 175-86. [CrossRef]
8. 8. Purroy F, Begue R, Gil MI, Quílez A, Sanahuja J, Brieva L, et al. Patterns of diffusion-weighted magnetic resonance imaging associated with etiology improve the accuracy of prognosis after transient ischaemic attack. Eur J Neurol 2011;18:121-8. [CrossRef]

9. 9. Hakyemez B, Aksoy U, Yildiz H, Ergin N. Intracranial epidermoid cysts: diffusion weighted, FLAIR and conventional MR findings. Eur J Radiol 2005;54:214-20. [CrossRef]
10. 10. Mayo JR, MacKay A, Muller NL. MR imaging of thelungs: value of short TE spin-echopulse sequences. AJR Am J Roentgenol 1992;159:951-6. [CrossRef]
11. 11. Schaefer JF, Vollmar J, Schick F, Vonthein R, Seemann MD, Aebert H, et al. Solitary pulmonary nodules: dynamic contrast enhanced MR imaging perfusion differences in malignant and benign lesions. Radiology 2004;232:544-53. [CrossRef]
12. 12. Hittmair K, Eckersberger F, Klepetko W, Helbich T, Herold CJ. Evaluation of solitary pulmonary nodules with dynamic contrast enhanced MR imaging: a promising technique. Magn Reson Imaging 1995;13:923-33. [CrossRef