Arterial Spin-Labeling and DSC Perfusion Metrics Improve Agreement in Neuroradiologists' Clinical Interpretations of Posttreatment High-Grade Glioma Surveillance MR Imaging-An Institutional Experience

Abstract

Background and purpose: MR perfusion has shown value in the evaluation of posttreatment high-grade gliomas, but few studies have shown its impact on the consistency and confidence of neuroradiologists' interpretation in routine clinical practice. We evaluated the impact of adding MR perfusion metrics to conventional contrast-enhanced MR imaging in posttreatment high-grade glioma surveillance imaging.

Materials and methods: This retrospective study included 45 adults with high-grade gliomas who had posttreatment perfusion MR imaging. Four neuroradiologists assigned Brain Tumor Reporting and Data System scores for each examination on the basis of the interpretation of contrast-enhanced MR imaging and then after the addition of arterial spin-labeling-CBF, DSC-relative CBV, and DSC-fractional tumor burden. Interrater agreement and rater agreement with a multidisciplinary consensus group were assessed with κ statistics. Raters used a 5-point Likert scale to report confidence scores. The frequency of clinically meaningful score changes resulting from the addition of each perfusion metric was determined.

Results: Interrater agreement was moderate for contrast-enhanced MR imaging alone (κ = 0.63) and higher with perfusion metrics (arterial spin-labeling-CBF, κ = 0.67; DSC-relative CBV, κ = 0.66; DSC-fractional tumor burden, κ = 0.70). Agreement between raters and consensus was highest with DSC-fractional tumor burden (κ = 0.66-0.80). Confidence scores were highest with DSC-fractional tumor burden. Across all raters, the addition of perfusion resulted in clinically meaningful interpretation changes in 2%-20% of patients compared with contrast-enhanced MR imaging alone.

Conclusions: Adding perfusion to contrast-enhanced MR imaging improved interrater agreement, rater agreement with consensus, and rater confidence in the interpretation of posttreatment high-grade glioma MR imaging, with the highest agreement and confidence scores seen with DSC-fractional tumor burden. Perfusion MR imaging also resulted in interpretation changes that could change therapeutic management in up to 20% of patients.

FIG 1.

Example of rater BT-RADS scores in a 57-year-old woman with previously treated GBM and worsening findings on surveillance MR imaging. The T1 postgadolinium image demonstrates an enhancing lesion in the left mesial temporal lobe. The lesion has elevated ASL-CBF and DSC-rCBV (white arrows). The DSC-FTB image shows that the enhancing voxels are in the “high” fractional tumor burden (red voxels) category. The addition of perfusion metrics to CE-MR imaging resulted in a scoring upgrade from 3b (worsening imaging findings, indeterminate mix of treatment effects and tumor) to 3c/4 (likely tumor progression) across all raters and agreed with the consensus score of 3c/4. For 3 of 4 raters, the upgrade occurred with all perfusion metrics, and for rater 2, it occurred only with DSC-FTB.

FIG 2.

Example of rater BT-RADS scores in a 61-year-old woman with previously treated GBM and equivocally worsening findings on surveillance MR imaging. The T1 postgadolinium image demonstrates an enhancing lesion in the right temporal lobe. The lesion shows no elevated ASL-CBF or DSC-rCBV, and DSC-FTB shows that the enhancing voxels are in the “low” FTB (blue voxels) category. For two raters, the addition of perfusion metrics to CE-MR imaging resulted in a scoring downgrade from 3b (worsening imaging findings, indeterminate mix of treatment effects and tumor) to 3a (worsening imaging findings, likely treatment effects). For the other raters, perfusion metrics did not influence their assessment. The consensus score in this case was 2 (no change). The discrepancy between the consensus group and the raters was due to differences in opinion as to whether the enhancing lesion had subtly increased in size from the prior MR imaging (not shown).

FIG 3.

Clinically meaningful changes in BT-RADS scores following the inclusion of perfusion metrics compared with conventional CE-MR imaging alone. Clinically meaningful upgrades or downgrades were defined as score changes from ≤3a⇆3b or 3b⇆3c/4 and from 3c/4⇆≤3b or 3b⇆≤3a, respectively. The numbers and arrows above the bar graph indicate the number of score upgrades (upward facing arrow) or downgrades (downward facing arrow). The greatest number of score changes was observed with the addition of DSC-FTB.

FIG 4.

Rater confidence in MR imaging interpretation. Raters graded their confidence in interpretation and assignment of BT-RADS scores for conventional CE-MR imaging, CE-MR imaging + ASL-CBF, CE-MR imaging + DSC-rCBV, and CE-MR imaging + DSC-FTB using a 5-point Likert scale. The number to the right of each color bar represents the mean score. In general, confidence was higher with the addition of any perfusion metric but was highest with DSC-FTB in all raters.