Differentiation of pilocytic and pilomyxoid astrocytomas using dynamic susceptibility contrast perfusion and diffusion weighted imaging
Pilocytic (PA) and pilomyxoid astrocytomas (PMA) are related low-grade tumors which occur predominantly in children. PMAs have a predilection for a supratentorial location in younger children with worse outcomes. However, the two have similar imaging characteristics. Quantitative MR sequences such as dynamic susceptibility contrast (DSC) perfusion and diffusion (DWI) were assessed for significant differences between the two tumor types and locations.
A retrospective search for MRI with DSC and DWI on pathology-proven cases of PMA and PA in children was performed. Tumors were manually segmented on anatomic images registered to rCBV, K2, and ADC maps. Tumors were categorized as PA or PMA, with subclassification of supratentorial and infratentorial locations. Mean values were obtained for tumor groups and locations compared with Student’s t test for significant differences with post hoc correction for multiple comparisons. ROC analysis for significant t test values was performed. Histogram evaluation was also performed.
A total of 49 patients met inclusion criteria. This included 30 patients with infratentorial PA, 8 with supratentorial PA, 6 with supratentorial PMA, and 5 with infratentorial PMA. Mean analysis showed significantly increased rCBV for infratentorial PMA (2.39 ± 1.1) vs PA (1.39 ± 0.16, p = 0.0006). ROC analysis for infratentorial PA vs PMA yielded AUC = 0.87 (p < 0.001). Histogram analysis also demonstrated a higher ADC peak location for PMA (1.8 ± 0.2) vs PA (1.56 ± 0.28).
PMA has a significantly higher rCBV than PA in the infratentorial space. DSC perfusion and diffusion MR imaging may be helpful to distinguish between the two tumor types in this location.
KeywordsDynamic susceptibility contrast Perfusion imaging Diffusion weighted imaging Apparent diffusion coefficient Pilocytic astrocytoma Pilomyxoid astrocytoma
No funding supported this work.
Compliance with ethical standards
Conflict of interest
The authors declare they have no conflicts of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee (include name of committee + reference number) and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
For this retrospective study, formal consent is not required.
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