Differentiation of Cerebral Neoplasms with Vessel Size Imaging (VSI)

Abstract

Purpose: Cerebral neoplasms of various histological origins may show comparable appearances on conventional Magnetic Resonance Imaging (MRI). Vessel size imaging (VSI) is an MRI technique that enables noninvasive assessment of microvasculature by providing quantitative estimates of microvessel size and density. In this study, we evaluated the potential of VSI to differentiate between brain tumor types based on their microvascular morphology.

Methods: Using a clinical 3T MRI scanner, VSI was performed on 25 patients with cerebral neoplasms, 10 with glioblastoma multiforme (GBM), 8 with primary CNS lymphoma (PCNSL) and 7 with cerebral lung cancer metastasis (MLC). Following the postprocessing of VSI maps, mean vessel diameter (vessel size index, vsi) and microvessel density (Q) were compared across tumors, peritumoral areas, and healthy tissues.

Results: The MLC tumors have larger and less dense microvasculature compared to PCNSLs in terms of vsi and Q (p = 0.0004 and p < 0.0001, respectively). GBM tumors have higher yet non-significantly different vsi values than PCNSLs (p = 0.065) and non-significant differences in Q. No statistically significant differences in vsi or Q were present between GBMs and MLCs. GBM tumor volume was positively correlated with vsi (r = 0.502, p = 0.0017) and negatively correlated with Q (r = -0.531, p = 0.0007).

Conclusion: Conventional MRI parameters are helpful in differentiating between PCNSLs, GBMs, and MLCs. Additionally incorporating VSI parameters into the diagnostic protocol could help in further differentiating between PCNSLs and metastases and potentially between PCNSLs and GBMs. Future studies in larger patient cohorts are required to establish diagnostic cut-off values for VSI.

Keywords: Brain imaging; Brain tumors; Differential diagnosis; Magnetic resonance imaging; Microvasculature.

Fig. 1

Manual selection of the regions of interest (ROIs) on postcontrast T1-weighted images. a tumor (yellow), b peritumoral area (green), c healthy gray matter from both thalami (orange), and d healthy white matter from the centrum semiovale (blue)

Fig. 2

VSI maps shown using the NORA medical imaging platform in patients with a glioblastoma multiforme, b primary CNS lymphoma, c metastatic lung cancer. Left: post-contrast T1-weighted images showing enhancement of tumor regions. Middle: corresponding mean vessel diameter (vsi) maps. Right: corresponding microvessel density (Q) maps. Tumor regions show elevated mean vessel diameters with decreased microvessel densities compared to healthy tissues

Fig. 3

Boxplot representation of vessel size index (vsi) (a) and microvessel density (Q) (b) in different tumor types, their surrounding areas, and healthy gray and white matters. Whiskers indicate 5–95 percentiles. GBM glioblastoma multiforme, PCNSL primary CNS lymphoma, MLC metastatic lung cancer, GM gray matter, WM white matter

Fig. 4

Scatterplot representation of the correlation analysis between tumor volumes and VSI parameters within glioblastoma multiforme (GBM) tumors. a Vessel size index (vsi) shows a relatively strong positive linear relationship with tumor volume (r = 0.502, n = 37, p = 0.0017). b Microvessel density (Q) shows a relatively strong negative correlation with tumor volume (r = −0.531, n = 37, p = 0.0007). Error bars indicate 95% CI. Note: various types of noise (image acquisition, co-registration, partial volume effect, etc.) may contribute to a certain variability in the final datapoints in the figure. This is particularly true for lesions with very small volume