Experimenting with ASL-based arterialized cerebral blood volume as a novel imaging biomarker in grading glial neoplasms

Abstract

Background: Perfusion imaging is one of the methods used to grade glial neoplasms, and in this study we evaluated the role of ASL perfusion in grading brain glioma.

Purpose: The aim is to evaluate the role of arterialized cerebral blood volume (aCBV) of multi-delay ASL perfusion for grading glial neoplasm.

Materials and methods: This study is a prospective observational study of 56 patients with glial neoplasms of the brain who underwent surgery, and only cases with positive diagnosis of glioma are included to evaluate the novel diagnostic parameter.

Results: In the study, ASL-derived normalized aCBV (naCBV) and T2*DSC-derived normalized CBV (nCBV) are showing very high correlation (Pearson's correlation coefficient value of 0.94) in grading glial neoplasms. naCBV and nCBF are also showing very high correlation (Pearson's correlation coefficient value of 0.876). The study also provides cutoff values for differentiating LGG from HGG for normalized aCBV(naCBV) of ASL, normalized CBV (nCBV), and normalized nCBF derived from T2* DCS as 1.12, 1.254, and 1.31, respectively. ASL-derived aCBV also shows better diagnostic accuracy than ASL-derived CBF.

Conclusion: This study is one of its kind to the best of our knowledge where multi-delay ASL perfusion-derived aCBV is used as a novel imaging biomarker for grading glial neoplasms, and it has shown high statistical correlation with T2* DSC-derived perfusion parameters.

Keywords: Perfusion magnetic resonance imaging; T2*dynamic susceptibility contrast; arterial spin labeling; cerebral blood volume; glioma.

Figure 1.

Receiver operating curve for normalized arterialized CBV (naCBV).

Figure 2.

Scatter plot showing correlation between normalized arterialized CBV (naCBV) and normalized CBV (nCBV).

Figure 3.

Receiver operating curve for normalised CBV (nCBV).

Legend 1.

Glioblastoma WHO grade 4 IDH mutant. A 66-year-old female patient presented with headache of 3 months duration with associated episodes of vomiting and no neurological deficits. MRI T2WI axial image (Figure (a)) shows a heterogeneous hyperintense lesion in left frontoparietal region which on post-contrast T1WI (Figure (b)) shows predominantly peripheral enhancement shaggy wall and irregular inner margins. On DWI (Figure (c)) with b values of 1000 m²/s. Images there is heterogeneous restriction of diffusion noted, on SWI (Figure (d)) the lesion shows few foci of blooming within, suggestive of hemorrhagic foci. On ASL perfusion imaging (Figure (e)), the aCBV map shows a normalized aCBV (naCBV) value of 2.86 and T2* DSC-generated normalized rCBV (Figure (f)) value of 2.52 within the lesion at the same location. On histopathological evaluation, it turned out to be glioblastoma WHO grade 4-IDH mutant.

Legend 2.

Anaplastic astrocytoma WHO grade 3 IDH mutant. A 56-year-old male with a history of unprovoked complex partial seizure. MRI scan shows FLAIR axial image (Figure (b)) with a hyperintense lesion in the left para central lobule and cingulate gyrus. It shows few foci of nodular enhancement within on T1WI post-contrast images (Figure (c)) and blooming on SWI (Figure (d)). On T2 DSC perfusion imaging (Figure (e)), the lesion shows increased perfusion. The value of normalized rCBV in the region is 1.46. Normalized aCBV (Figure (f)) in the region of tumor is 1.40. On histopathological evaluation, it was anaplastic astrocytoma WHO grade 3-IDH mutant.

Legend 3.

Glioma WHO grade 2 IDH mutant. A 33-year-old female presented with headache of 6 months duration. MRI scan shows a T2WI (Figure (c)) hyperintense lesion in the splenium of corpus callosum with extension on either side of midline with few areas appearing hypointense on FLAIR axial (Figure (a)) suggestive of T2-FLAIR mismatch. It appears hypointense on T1WI (Figure (b)). On perfusion imaging, the lesion shows low perfusion. The value of normalized T2*DSC perfusion rCBV (Figure (e)) in the lesion is 0.76. ASL perfusion (Figure (f)) also shows low value (0.70) of normalized aCBV in the region of tumor which corresponds with the low perfusion on T2* DSC perfusion imaging. On histopathological evaluation, it turned out to be diffuse astrocytoma WHO grade 2-IDH mutant.