Background <p>Unresectable WHO grade&#xa0;II astrocytomas require continuous imaging surveillance. To evaluate whether sodium MRI (<sup>23</sup>Na-MRI) adds diagnostic value to multiparametric MRI and helps predict progressive disease (PD), patients monitored under a&#xa0;“watchful waiting” strategy were repeatedly examined.</p> Materials and methods <p>Overall, 18 patients with biopsy-proven WHO grade&#xa0;II astrocytoma (10 female, mean age&#xa0;42 ± 15&#xa0;years) were prospectively included after baseline imaging. The imaging protocol comprised morphological MRI (T2 TSE, T2 FLAIR, pre- and post-contrast T1 SE), DSC perfusion MRI (<i>n</i> = 17), and <sup>23</sup>Na-MRI (<i>n</i> = 9) at 3 T. At baseline, evaluable <sup>23</sup>Na-MRI was available for six patients. The Response Assessment in Neuro-Oncology criteria were used to define PD. Semiquantitative ROI analysis was performed on DSC- and <sup>23</sup>Na-MRI. Data were analyzed using the Cox regression model.</p> Results <p>In 14&#xa0;patients (78%), PD was found after a&#xa0;mean of 420 ± 354&#xa0;days. For the endpoint time to progression, univariate Cox regression revealed a&#xa0;hazard ratio (HR) of 1.39 for relative regional cerebral blood volume (rrCBV) in the tumor at baseline, and an&#xa0;HR of 1.29 for relative regional cerebral blood flow (rrCBF) at baseline. The <sup>23</sup>Na signal in tumor tissue at baseline, normalized to sodium phantoms, revealed an&#xa0;HR of 0.91.</p> Conclusion <p>Elevation of rrCBV and rrCBF in the tumor indicates poor prognosis, in line with the literature. <sup>23</sup>Na-MRI can be used for WHO grade&#xa0;II astrocytoma surveillance. In some treatment-naïve WHO grade&#xa0;II astrocytomas, an initially high sodium signal seems to be prognostically favorable, contrary to the literature on <sup>23</sup>Na-MRI in postoperative aftercare. However, due to the small cohort size with evaluable <sup>23</sup>Na-MRI at baseline, evidence is limited. In future, <sup>23</sup>Na-MRI may help selecting patients for a&#xa0;“watchful waiting” strategy.</p>

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Added value of sodium MRI in multiparametric MRI for WHO grade II astrocytoma surveillance during “watchful waiting”: initial experience

  • Daniel Cantré,
  • Ioan Gemescu,
  • Lars Gerigk,
  • Armin M. Nagel,
  • Marco Essig,
  • Sönke Langner,
  • Marc-André Weber

摘要

Background

Unresectable WHO grade II astrocytomas require continuous imaging surveillance. To evaluate whether sodium MRI (23Na-MRI) adds diagnostic value to multiparametric MRI and helps predict progressive disease (PD), patients monitored under a “watchful waiting” strategy were repeatedly examined.

Materials and methods

Overall, 18 patients with biopsy-proven WHO grade II astrocytoma (10 female, mean age 42 ± 15 years) were prospectively included after baseline imaging. The imaging protocol comprised morphological MRI (T2 TSE, T2 FLAIR, pre- and post-contrast T1 SE), DSC perfusion MRI (n = 17), and 23Na-MRI (n = 9) at 3 T. At baseline, evaluable 23Na-MRI was available for six patients. The Response Assessment in Neuro-Oncology criteria were used to define PD. Semiquantitative ROI analysis was performed on DSC- and 23Na-MRI. Data were analyzed using the Cox regression model.

Results

In 14 patients (78%), PD was found after a mean of 420 ± 354 days. For the endpoint time to progression, univariate Cox regression revealed a hazard ratio (HR) of 1.39 for relative regional cerebral blood volume (rrCBV) in the tumor at baseline, and an HR of 1.29 for relative regional cerebral blood flow (rrCBF) at baseline. The 23Na signal in tumor tissue at baseline, normalized to sodium phantoms, revealed an HR of 0.91.

Conclusion

Elevation of rrCBV and rrCBF in the tumor indicates poor prognosis, in line with the literature. 23Na-MRI can be used for WHO grade II astrocytoma surveillance. In some treatment-naïve WHO grade II astrocytomas, an initially high sodium signal seems to be prognostically favorable, contrary to the literature on 23Na-MRI in postoperative aftercare. However, due to the small cohort size with evaluable 23Na-MRI at baseline, evidence is limited. In future, 23Na-MRI may help selecting patients for a “watchful waiting” strategy.