Use of Susceptibility-Weighted Imaging (SWI) in the Detection of Brain Hemorrhagic Metastases from Breast Cancer and Melanoma

Abstract

Purpose SWI has significantly increased our sensitivity in detecting hemorrhagic brain lesions. We sought to explore the prevalence of intra-tumoral hemorrhage as detected by SWI in brain metastases from melanoma and breast cancer. Methods Lesions with a size of 0.1 cm3 were categorized as micro-metastases while larger lesions were categorized as macro-metastases. SWI findings on locations corresponding to enhancing lesions were categorized as either positive or negative based on presence/absence of signal dropout. The percentage of SWI positivity was then estimated as a function of lesion size. Two-tailed Fisher's exact test was performed to examine differences in the contingency tables. Results MRI studies from 73 patients with 1,173 brain metastases which enhanced on post-contrast T1-weighted imaging (T1WI) were selected for analysis. Of these lesions, 952 had SWI data available, and 342 out of 952 were micro-metastases. Only 10 of the 342 micro-metastases and 410 of the 610 macro-metastases were SWI positive (67.2%, p-value of < 0.0001). When examined by tumor type, 76.9% (melanoma) versus 55.6% (breast cancer) were SWI positive (p-value < 0.0001), regardless of tumor size. All melanoma lesions (8/8) and only 1 out of 15 breast cancer lesions larger than 1.5 cm3 were SWI positive. Conclusion Using combined SWI and contrast-enhanced high-resolution T1 imaging we found that presence of intra-tumoral brain hemorrhage is uncommon in micro-metastases but common in metastases > 0.1 cm3 from breast cancer or melanoma. Large metastases commonly harbored hemorrhage and this occurred more frequently in patients with melanoma than with breast cancer.

Brain metastases: neuroimaging

“…Thus these techniques may improve detection of hemorrhagic metastases, particularly melanoma (Gaviani et al, 2006). SWI has been found to increase the sensitivity for the detection of small hemorrhagic metastases, although very small lesions (< 1 mm) are rarely SWI-positive (Franceschi et al, 2016). …”

“…The majority of both breast (56%) and melanoma (77%) metastases have abnormal SWI signal; that is, they are SWI+. Therefore a binary classification system (SWI+ vs. SWI−) does not distinguish between the two (Franceschi et al, 2016). However, when the amount of SWI signal abnormality within a metastatic lesion is quantified, melanoma can be distinguished from both breast and bronchial cancer with excellent accuracy (receiver operating characteristic 0.96 and 0.81 respectively), as melanoma metastases tend to have a larger percentage of voxels that show abnormal SWI hypointentsity (Radbruch et al, 2012).…”

Susceptibility-Based Neuroimaging: Standard Methods, Clinical Applications, and Future Directions

“…[60] Delimitation of the peripheral tumoral invasion zone with high vascularity has improved using contrast-enhanced SWI. [61] Human and animal studies have shown even more detailed delineation using targeted superparamagnetic contrast agents using contrast enhanced SWI (CE-SWI).…”

Susceptibility‐weighted imaging in malignant melanoma brain metastasis

“…Recently, susceptibility‐weighted imaging (SWI) was additionally introduced into clinical practice and is readily used in melanoma patients . SWI is sensitive to susceptibility effects that can be caused by bleeds, deoxygenized blood within veins, calcification, or other sources of local magnetic field inhomogeneities (eg, at air–bone interfaces).…”

“…15 Recently, susceptibility-weighted imaging (SWI) was additionally introduced into clinical practice 16,17 and is readily used in melanoma patients. 18,19 SWI is sensitive to susceptibility effects that can be caused by bleeds, deoxygenized blood within veins, calcification, or other sources of local magnetic field inhomogeneities (eg, at air-bone interfaces). Among these effects, intracerebral "blooming artifacts" are of particular diagnostic interest because very small lesions lead to a magnified signal dropout that can thus be detected.…”