Added value and diagnostic performance of intratumoral susceptibility signals in the differential diagnosis of solitary enhancing brain lesions: preliminary study

Abstract

Background and purpose: It has been reported that high-resolution susceptibility-weighted imaging (HR-SWI) is a promising tool for assessing brain tumor characterization noninvasively. The purpose of this study was to determine the added value and diagnostic performance of HR-SWI for differentiating solitary enhancing brain lesions (SELs) by assessing intratumoral susceptibility signals (ITSSs).

Materials and methods: Sixty-four consecutive patients with SELs, without previous surgery, were retrospectively reviewed. We performed 2 consensus reviews, by using conventional MR images alone and with adjunctive HR-SWI. We applied an ITSS grading system based on the degree of the ITSS. Then, we compared the presence and grade of the ITSSs among specific pathologic types of SELs.

Results: Two observers diagnosed tumor pathology accurately in 43 (67%) of 64 SELs after reviewing the conventional images alone and 50 (78%) of 64 SELs after reviewing the adjunctive HR-SWI (P = .016, McNemar test). ITSSs were seen in 25 (100%) of 25 glioblastoma multiformes (GBMs), in 2 (40%) of 5 anaplastic astrocytomas, and in 11 (73%) of 15 metastatic tumors. Although the ITSSs were unable to distinguish between GBMs and solitary metastatic tumors, differentiation between GBMs and solitary metastatic tumors was achieved (P = .01) by using a high ITSS degree (grade 3). Moreover, the ITSSs could discriminate high-grade gliomas from lymphomas and nontumorous lesions with a specificity of 100% (P < .0001).

Conclusions: The use of ITSSs on HR-SWIs significantly improves the accuracy for the differential diagnosis of SELs compared with the use of conventional MR imaging alone.

Fig 1.

The grade of intratumoral susceptibility signals on HG-SWI. A, Grade 1 (arrow). B, Grade 2 (circle). C, Grade 3 (arrow).

Fig 2.

MR images of a 51-year-old woman with a left temporal GBM. A, The contrast-enhanced axial T1-weighted image shows a mass with peripheral rim enhancement. B, HR-SWI demonstrates conglomerated dotlike and fine linear ITSSs (grade 3, arrows) in the periphery of the mass.

Fig 3.

MR images of a 76-year-old man with a solitary metastatic brain tumor. A, The axial T2-weighted image shows a mass with central necrosis in left frontal lobe. B, The contrast-enhanced axial T1-weighted image shows the mass with irregular peripheral rim enhancement. C, HR-SWI reveals scattered dotlike ITSSs (grade 2, arrow) in the periphery of the mass.

Fig 4.

MR images of a 45-year-old man with lymphoma. A, The axial T2-weighted image shows an ill-defined mass with high signal intensity in the right frontal lobe. B, The contrast-enhanced axial T1-weighted image shows the mass with peripheral enhancement. C, No evidence of an ITSS (grade 1) is seen within the mass on HR-SWI.

Fig 5.

MR images of a 47-year-old man with a fungal granuloma. A, The axial T2-weighted image shows a mass with central necrosis and surrounding edema in the left pons. B, The contrast-enhanced axial T1-weighted image shows the mass with irregular peripheral rim enhancement. C, Apparent diffusion coefficient shows relatively restricted diffusion in the periphery of the mass. D, HR-SWI reveals fuzzy and diffuse low signals (not defined as ITSS in the present study) in the periphery of the mass.

Fig 6.

ROC curve analysis of the degree of ITSS for correctly identifying GBM (WHO grade IV). The area under the ROC curve for the degree of ITSS is 0.898 (95% CI, 0.797–0.960). The sensitivity, specificity, PPV, and NPV for differentiating GBMs and other SELs by using high-grade ITSSs (grade 3) are 84.0, 84.6, 77.8, and 89.2%, respectively.