Introduction

The aim of our study was to describe the incidence and distribution pattern of intratumoral susceptibility signals (ITSS) in brain tumors, and to determine whether the distribution pattern of ITSS derived from susceptibility weighted imaging (SWI) could characterize the difference of the ultrastructure of tumor capillaries and differentiate glioblastoma multiforme (GBM) and single brain metastasis.

Methods

58 intracranial brain neoplasm patients (55 male and 3 female, age 69.8 ± 8.2 years (mean ± SD), 42 brain metastases and 16 with GBM) were enrolled in this study. These patients underwent examinations that included SWI in addition to conventional magnetic resonance (MR) sequences on a 3T. Two radiologists investigated the distribution patterns of ITSS of the tumors and applied an ITSS grading system based on the degree of the ITSS. Magnetic ITSS were defined as either linear hypointense signal that was regarded as intralesional vessels which would be followed on consecutive SWI images or dot like foci of low signal intensity that was regarded as microhemorrhage on SWI imaging that covers whole tumor area. Two radiologists investigated the distribution patterns of ITSS of the tumors and applied an ITSS grading system based on the degree of the ITSS. Then, we compared the grade of the visibility of ITSS in the central portion of tumors; the inner three quarters area of tumor volume (CITSS) and in the tumor capsular area; the outside one quarter area of tumor volume (PITSS) on SWI. The visibility of ITSS of tumors were graded as follows: 0 = no intralesional ITSS, 1 = 1~5 of ITSS, 2 = 6~10, 3 = 11~15, and 4 = conglomerated ITSS on SWI.

Results

The mean score and standard deviation of the visibility of the ITSS in the central portion of the tumor and the tumor capsular area ITSS are presented in Table 1-3. The mean visibility scores of the CITSS is higher than PITSS in GBM (p < 0.0001) and the mean visibility scores of the CITSS is lower than PITSS in brain metastases (p < 0.0001). Wilcoxon rank sum test showed that the CITSS in GBM was statistically higher than brain metastasis (p < 0.0001)(Fig. 1) and the PITSS in GBM was statistically lower than brain metastasis (p < 0.0001)(Fig. 2). We found that the CITSS is more frequently seen in GBM than brain metastasis, and the PITSS is in brain metastasis than GBM (Fig. 3, 4).

Discussion

Our findings suggest that there were different characteristics of ITSS between GBM and brain metastasis on SWI due to the profound difference in histologic feature of capillary between the two tumor types. The CITSS within the GBM represents the complex immature neovascularity and blood leakage and PITSS in the metastasis represents the mechanical disruption of the BBB lack capillaries and prominent feeding or draining vessels.

Conclusion

Differentiation could be achieved between GBMs and brain metastases using the ITSS distribution pattern of the brain tumors.

Acknowledgements

No acknowledgement found.

References

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