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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 early and late postoperative MRI based on T2-weighted imaging and FLAIR-weighted imaging shown as data plots (a and b) and Bland-Altman plots (c and d) respectively depicting systematic overestimation of residual tumour volume by early postoperative MRI. Each data point represents measurements obtained from one patient, tagged by glioma grade according to the legend. The straight diagonal line in a and b represents hypothetical perfect agreement and the dotted lines the actual linear regression fit and corresponding 95% confidence interval. The three dotted horizontal lines in c and d represent the average differential volume and corresponding 95% confidence interval
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Fig1: Residual tumour volumes in mL comparing early and late postoperative MRI based on T2-weighted imaging and FLAIR-weighted imaging shown as data plots (a and b) and Bland-Altman plots (c and d) respectively depicting systematic overestimation of residual tumour volume by early postoperative MRI. Each data point represents measurements obtained from one patient, tagged by glioma grade according to the legend. The straight diagonal line in a and b represents hypothetical perfect agreement and the dotted lines the actual linear regression fit and corresponding 95% confidence interval. The three dotted horizontal lines in c and d represent the average differential volume and corresponding 95% confidence interval

Mentions: The median early and late T2 residual volumes were 28.7 cm3 and 22.4 cm3, respectively, resulting in a 22% smaller residual volume on late T2 images. Residual T2 tumour volumes on early postoperative MRI demonstrated a systematically larger residual tumour volume (on average 4.3 cm3) compared with late postoperative MRI (Fig. 1a, c) with a regression coefficient of 0.767 (95%CI: 0.665–0.870), a correlation coefficient of 0.81 (p < 0.0001) and a paired Wilcoxon rank sum of V = 746.5 (p = 0.295). Similarly, the median early and late FLAIR residual volumes were 27.3 cm3 and 13.9 cm3, respectively, resulting in a 49% smaller residual volume on late FLAIR images. Systematically larger residual FLAIR tumour volumes (on average 5.7 cm3) were observed based on early postoperative MRI compared with late postoperative MRI (Fig. 1b, d) with a regression coefficient of 0.833 (95%CI: 0.693–0.973), a correlation coefficient of 0.95 (p < 0.0001) and a paired Wilcoxon rank sum of V = 78 (p = 0.119). Data plots confirmed that the differential residual tumour volumes were independent of glioma grading, subtyping and timing of late postoperative MRI.Fig. 1


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 early and late postoperative MRI based on T2-weighted imaging and FLAIR-weighted imaging shown as data plots (a and b) and Bland-Altman plots (c and d) respectively depicting systematic overestimation of residual tumour volume by early postoperative MRI. Each data point represents measurements obtained from one patient, tagged by glioma grade according to the legend. The straight diagonal line in a and b represents hypothetical perfect agreement and the dotted lines the actual linear regression fit and corresponding 95% confidence interval. The three dotted horizontal lines in c and d represent the average differential volume and corresponding 95% confidence interval
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3101346&req=5

Fig1: Residual tumour volumes in mL comparing early and late postoperative MRI based on T2-weighted imaging and FLAIR-weighted imaging shown as data plots (a and b) and Bland-Altman plots (c and d) respectively depicting systematic overestimation of residual tumour volume by early postoperative MRI. Each data point represents measurements obtained from one patient, tagged by glioma grade according to the legend. The straight diagonal line in a and b represents hypothetical perfect agreement and the dotted lines the actual linear regression fit and corresponding 95% confidence interval. The three dotted horizontal lines in c and d represent the average differential volume and corresponding 95% confidence interval
Mentions: The median early and late T2 residual volumes were 28.7 cm3 and 22.4 cm3, respectively, resulting in a 22% smaller residual volume on late T2 images. Residual T2 tumour volumes on early postoperative MRI demonstrated a systematically larger residual tumour volume (on average 4.3 cm3) compared with late postoperative MRI (Fig. 1a, c) with a regression coefficient of 0.767 (95%CI: 0.665–0.870), a correlation coefficient of 0.81 (p < 0.0001) and a paired Wilcoxon rank sum of V = 746.5 (p = 0.295). Similarly, the median early and late FLAIR residual volumes were 27.3 cm3 and 13.9 cm3, respectively, resulting in a 49% smaller residual volume on late FLAIR images. Systematically larger residual FLAIR tumour volumes (on average 5.7 cm3) were observed based on early postoperative MRI compared with late postoperative MRI (Fig. 1b, d) with a regression coefficient of 0.833 (95%CI: 0.693–0.973), a correlation coefficient of 0.95 (p < 0.0001) and a paired Wilcoxon rank sum of V = 78 (p = 0.119). Data plots confirmed that the differential residual tumour volumes were independent of glioma grading, subtyping and timing of late postoperative MRI.Fig. 1

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