Diagnostic value of susceptibility⁃weighted imaging in grading diffusely infiltrating astrocytomas

Abstract

Objective To investigate the diagnostic value of susceptibility⁃weighted imaging (SWI) in grading diffusely infiltrating astrocytomas. Methods Forty⁃three patients with pathologically proven diffusely infiltrating astrocytomas were collected, and underwent preoperative MRI conventional sequences (including axial T1WI, T2WI and FLAIR) and axial SWI. The ability of showing intratumoral small vessels and hemorrhagic focuses were compared between SWI and conventional techniques. The signal intensities, distribution of venules and bleeding incidence of the tumors were observed respectively on SWI, and the numbers of intratumoral small vessels and cerebral microbleeds, and the sectional areas of bleedings were compared within the three grades of astrocytomas. Results There were significant differences between SWI and conventional sequences in displaying numbers of small vessels and microbleeds and sizes of bleedings (P < 0.01, for all). Low⁃grade astrocytomas (WHO Ⅱ) displayed mainly as hyperintense, while high ⁃ grade (WHO Ⅲ, Ⅳ) ones showed mainly equisignal or low intensities; venules inside low ⁃ grade astrocytomas were sparse, but abundant inside high⁃grade ones; the incidence of hemorrhage in low⁃grade astrocytomas was less frequent than that in high⁃grade ones. The numbers of venules in three groups were 3.77 ± 1.11, 11.86 ± 1.22 and 20.00 ± 1.32, respectively. The numbers of cerebral microbleeds were 0.47 ± 0.39, 3.32 ± 0.42 and 4.38 ± 0.46, respectively. The sectional areas of bleedings were (0.78 ± 1.31) cm2, (3.05 ± 4.40) cm2 and (4.23 ± 4.55) cm2, respectively. The differences among the three groups were all statistically significant (P < 0.01, for all). Conclusion SWI was more sensitive than conventional techniques in showing small vessels and bleeding sites in astrocytomas. The signal intensities, distribution of venules and bleeding incidence of tumors were significantly different between low⁃grade and high⁃grade astrocytomas. The numbers of small vessels and cerebral microbleeds, and the sectional areas of bleedings may help to facilitate the grading of astrocytomas in clinical practice.

DOI：10.3969/j.issn.1672⁃6731.2012.06.009