Purpose: To use directed biopsy sampling to determine whether microvascular assessment within gliomas, by means of ultrahigh-field-strength high-spatial-resolution gradient-echo (GRE) magnetic resonance (MR) imaging at 8 T, correlates with histopathologic assessment of microvascularity.
Materials and methods: The study was institutional review board approved and HIPAA compliant. Informed consent was obtained. Thirty-five subjects with gliomas underwent 8-T and 80-cm MR imaging by using a GRE sequence (repetition time, 600-750 msec; echo time, 10 msec; in-plane resolution, 196 mm). Haphazardly arranged serpentine low-signal-intensity structures, often associated with areas of low signal intensity within the tumor bed ("tumoral pseudoblush") at MR imaging, were presumed to be related to tumoral microvascularity. Microvessel density (MVD) and microvessel size (MVS) ranked with a semiquantitative three-tier scale (high, medium, and low) relative to cortical penetrating veins were assessed from regions of interest identified at MR imaging and were compared with a similar assessment of stereotactic biopsy specimens by using Kendall τb. Tumor grade (high vs low) was compared with ultrahigh-field-strength high-resolution GRE MR analysis by using Pearson χ2. Discrepancies between 8-T and histopathologic assessment were identified and analyzed.
Results: Ultrahigh-field-strength high-resolution GRE MR imaging and histopathologic assessment concurred for MVS (P<.0001) and MVD (P<.0001). World Health Organization classification tumor grade was associated with number (P<.0005) and size (P<.0005) of foci of microvascularity within the tumor bed at 8-T MR imaging. Radiation-induced microvessel hyalinosis mimicked tumor microvascularity at 8-T MR imaging. Potential confounders could result from radiofrequency inhomogeneity and displaced normal microvasculature.
Conclusion: Microvascularity identified as a tumoral pseudoblush at ultrahigh-field-strength high-resolution GRE MR imaging without contrast material shows promise as a marker for increased tumoral microvascularity.
© RSNA, 2012.