Contrast-enhanced MR Imaging versus Contrast-enhanced US: A comparison in glioblastoma surgery by using intraoperative fusion imaging

Purpose: To compare contrast material enhancement of glioblastoma multiforme (GBM) with intraoperative contrast-enhanced ultrasonography (US) versus that with preoperative gadolinium- enhanced T1-weighted magnetic resonance (MR) imaging by using real-time fusion imaging. Materials and Methods: Ten patients with GBM were retrospectively identified by using routinely collected, anonymized data. Navigated contrastenhanced US was performed after intravenous administration of contrast material before tumor resection. All patients underwent tumor excision with navigated intraoperative US guidance with use of fusion imaging between real-time intraoperative US and preoperative MR imaging. With use of fusion imaging, glioblastoma contrast enhancement at contrast-enhanced US (regarding location, morphologic features, margins, dimensions, and pattern) was compared with that at gadolinium-enhanced T1-weighted MR imaging. Results: Fusion imaging for virtual navigation enabled matching of realtime contrast-enhanced US scans to corresponding coplanar preoperative gadolinium-enhanced T1-weighted MR images in all cases, with a positional discrepancy of less than 2 mm. Contrast enhancement of gadolinium-enhanced T1-weighted MR imaging and contrast-enhanced US was superimposable in all cases with regard to location, margins, dimensions, and morphologic features. The qualitative analysis of contrast enhancement pattern demonstrated a similar distribution in contrast-enhanced US and gadolinium-enhanced T1-weighted MR imaging in nine patients: Seven lesions showed peripheral inhomogeneous ring enhancement, and two lesions showed a prevalent nodular pattern. In one patient, the contrast enhancement pattern differed between the two modalities: Contrast- enhanced US showed enhancement of the entire bulk of the tumor, whereas gadolinium-enhanced T1-weighted MR imaging demonstrated peripheral contrast enhancement. Conclusion: Glioblastoma contrast enhancement with contrast-enhanced US is superimposable on that provided with preoperative gadolinium- enhanced T1-weighted MR imaging regarding location, margins, morphologic features, and dimensions, with a similar enhancement pattern in most cases. Thus, contrast-enhanced US is of potential use in the surgical management of GBM.