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Early postoperative MRI overestimates residual tumour after resection of gliomas with no or minimal enhancement.

Belhawi SM, Hoefnagels FW, Baaijen JC, Aliaga ES, Reijneveld JC, Heimans JJ, Barkhof F, Vandertop WP, Hamer PC - Eur Radiol (2011)

Bottom Line: Residual tumour volumes were 22% smaller on late postoperative compared with early postoperative T2-weighted MRI and 49% smaller for FLAIR-weighted imaging.We observed a systematic and substantial overestimation of residual non-enhancing volume on MRI within 48 h of resection compared with months postoperatively, in particular for FLAIR imaging.Resection-induced ischaemia contributes to this overestimation, as may other operative effects.

View Article: PubMed Central - PubMed

Affiliation: Neurosurgical Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.

ABSTRACT

Background: Standards for residual tumour measurement after resection of gliomas with no or minimal enhancement have not yet been established. In this study residual volumes on early and late postoperative T2-/FLAIR-weighted MRI are compared.

Methods: A retrospective cohort included 58 consecutive glioma patients with no or minimal preoperative gadolinium enhancement. Inclusion criteria were first-time resection between 2007 and 2009 with a T2-/FLAIR-based target volume and availability of preoperative, early (<48 h) and late (1-7 months) postoperative MRI. The volumes of non-enhancing T2/FLAIR tissue and diffusion restriction areas were measured.

Results: Residual tumour volumes were 22% smaller on late postoperative compared with early postoperative T2-weighted MRI and 49% smaller for FLAIR-weighted imaging. Postoperative restricted diffusion volume correlated with the difference between early and late postoperative FLAIR volumes and with the difference between T2 and FLAIR volumes on early postoperative MRI.

Conclusion: We observed a systematic and substantial overestimation of residual non-enhancing volume on MRI within 48 h of resection compared with months postoperatively, in particular for FLAIR imaging. Resection-induced ischaemia contributes to this overestimation, as may other operative effects. This indicates that early postoperative MRI is less reliable to determine the extent of non-enhancing residual glioma and restricted diffusion volumes are imperative.

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Residual tumour volumes in mL comparing T2- and FLAIR-weighted imaging respectively based on preoperative, early postoperative and late postoperative MRI shown as data plots (a, b and c) and Bland Altman plots (d, e and f) depicting good agreement in residual tumour volume based on preoperative and late postoperative MRI and systematic overestimation of FLAIR-weighted imaging on early postoperative MRI. Data points, tagging and line styles as in Fig. 1
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Fig2: Residual tumour volumes in mL comparing T2- and FLAIR-weighted imaging respectively based on preoperative, early postoperative and late postoperative MRI shown as data plots (a, b and c) and Bland Altman plots (d, e and f) depicting good agreement in residual tumour volume based on preoperative and late postoperative MRI and systematic overestimation of FLAIR-weighted imaging on early postoperative MRI. Data points, tagging and line styles as in Fig. 1

Mentions: FLAIR tumour volumes were marginally larger (on average 4.7 cm3) compared with T2 volumes on preoperative MRI (Fig. 2a, d) with a regression coefficient of 1.068 (95%CI: 1.033–1.102), a correlation coefficient of 0.98 (p < 0.0001) and a paired Wilcoxon rank sum of V = 419.5 (p = 0.056). FLAIR residual tumour volumes were substantially larger (on average 7.2 cm3) than T2 tumour volumes on early postoperative MRI (Fig. 2b, e) with a regression coefficient of 1.156 (95%CI: 1.049–1.262), a correlation coefficient of 0.96 (p < 0.0001) and a paired Wilcoxon rank sum of V = 40 (p = 0.009). On the late postoperative MRI, FLAIR and T2 residual tumour volumes were comparable (Fig. 2c, f): T2 tumour volumes on average 1.5 cm3 larger with a regression coefficient of 0.948 (95%CI: 0.880–1.015), a correlation coefficient of 0.94 (p < 0.0001) and a paired Wilcoxon rank sum of V = 194 (p = 0.218). Again, data plots confirmed that the differential residual tumour volumes were independent of glioma grading and timing of late postoperative MRI.Fig. 2


Early postoperative MRI overestimates residual tumour after resection of gliomas with no or minimal enhancement.

Belhawi SM, Hoefnagels FW, Baaijen JC, Aliaga ES, Reijneveld JC, Heimans JJ, Barkhof F, Vandertop WP, Hamer PC - Eur Radiol (2011)

Residual tumour volumes in mL comparing T2- and FLAIR-weighted imaging respectively based on preoperative, early postoperative and late postoperative MRI shown as data plots (a, b and c) and Bland Altman plots (d, e and f) depicting good agreement in residual tumour volume based on preoperative and late postoperative MRI and systematic overestimation of FLAIR-weighted imaging on early postoperative MRI. Data points, tagging and line styles as in Fig. 1
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3101346&req=5

Fig2: Residual tumour volumes in mL comparing T2- and FLAIR-weighted imaging respectively based on preoperative, early postoperative and late postoperative MRI shown as data plots (a, b and c) and Bland Altman plots (d, e and f) depicting good agreement in residual tumour volume based on preoperative and late postoperative MRI and systematic overestimation of FLAIR-weighted imaging on early postoperative MRI. Data points, tagging and line styles as in Fig. 1
Mentions: FLAIR tumour volumes were marginally larger (on average 4.7 cm3) compared with T2 volumes on preoperative MRI (Fig. 2a, d) with a regression coefficient of 1.068 (95%CI: 1.033–1.102), a correlation coefficient of 0.98 (p < 0.0001) and a paired Wilcoxon rank sum of V = 419.5 (p = 0.056). FLAIR residual tumour volumes were substantially larger (on average 7.2 cm3) than T2 tumour volumes on early postoperative MRI (Fig. 2b, e) with a regression coefficient of 1.156 (95%CI: 1.049–1.262), a correlation coefficient of 0.96 (p < 0.0001) and a paired Wilcoxon rank sum of V = 40 (p = 0.009). On the late postoperative MRI, FLAIR and T2 residual tumour volumes were comparable (Fig. 2c, f): T2 tumour volumes on average 1.5 cm3 larger with a regression coefficient of 0.948 (95%CI: 0.880–1.015), a correlation coefficient of 0.94 (p < 0.0001) and a paired Wilcoxon rank sum of V = 194 (p = 0.218). Again, data plots confirmed that the differential residual tumour volumes were independent of glioma grading and timing of late postoperative MRI.Fig. 2

Bottom Line: Residual tumour volumes were 22% smaller on late postoperative compared with early postoperative T2-weighted MRI and 49% smaller for FLAIR-weighted imaging.We observed a systematic and substantial overestimation of residual non-enhancing volume on MRI within 48 h of resection compared with months postoperatively, in particular for FLAIR imaging.Resection-induced ischaemia contributes to this overestimation, as may other operative effects.

View Article: PubMed Central - PubMed

Affiliation: Neurosurgical Center Amsterdam, VU University Medical Center, Amsterdam, The Netherlands.

ABSTRACT

Background: Standards for residual tumour measurement after resection of gliomas with no or minimal enhancement have not yet been established. In this study residual volumes on early and late postoperative T2-/FLAIR-weighted MRI are compared.

Methods: A retrospective cohort included 58 consecutive glioma patients with no or minimal preoperative gadolinium enhancement. Inclusion criteria were first-time resection between 2007 and 2009 with a T2-/FLAIR-based target volume and availability of preoperative, early (<48 h) and late (1-7 months) postoperative MRI. The volumes of non-enhancing T2/FLAIR tissue and diffusion restriction areas were measured.

Results: Residual tumour volumes were 22% smaller on late postoperative compared with early postoperative T2-weighted MRI and 49% smaller for FLAIR-weighted imaging. Postoperative restricted diffusion volume correlated with the difference between early and late postoperative FLAIR volumes and with the difference between T2 and FLAIR volumes on early postoperative MRI.

Conclusion: We observed a systematic and substantial overestimation of residual non-enhancing volume on MRI within 48 h of resection compared with months postoperatively, in particular for FLAIR imaging. Resection-induced ischaemia contributes to this overestimation, as may other operative effects. This indicates that early postoperative MRI is less reliable to determine the extent of non-enhancing residual glioma and restricted diffusion volumes are imperative.

Show MeSH
Related in: MedlinePlus