Abstract
BACKGROUND AND PURPOSE: Focal anaplasia characterized by T2 hypointensity, signal-intensity enhancement on postcontrast T1-weighted MR imaging and restricted water diffusion has been reported in a patient with juvenile pilocytic astrocytoma. We identified T2HOF with these MR imaging characteristics in children with DIPG and hypothesized that these represent areas of focal anaplasia; and may, therefore, have increased perfusion properties and should be characterized by increased perfusion. Thus, we used DSC to investigate our hypothesis.
MATERIALS AND METHODS: We retrospectively reviewed the baseline MR imaging scans of 86 patients (49 girls, 37 boys; median age, 6.1 years; range, 1.1–17.6 years) treated for DIPG at our hospital (2004–2009). T2HOF with the described MR imaging characteristics was identified in 10 patients. We used a region of interest−based approach to compare the ADC, FA, rCBV, rCBF, and rMTT of T2HOF with those of the typical T2HRT.
RESULTS: The ADC of T2HOF with the specified MR imaging characteristics was significantly lower than that of T2HRT (range, 0.71–1.95 μm2/ms versus 1.36–2.13 μm2/ms; P < .01); and the FA (range, 0.12–0.34 versus 0.07–0.24; P = .03) and rCBV (range, 0.4–2.62 versus 0.23–1.57; P = .01) values of T2HOFs were significantly higher.
CONCLUSIONS: Our data suggest that T2HOF in DIPG may represent areas of focal anaplasia and underline the importance of regional, rather than global, tumor-field analysis. T2HOF may be the ideal target when stereotactic biopsy of tumors that present with an inhomogeneous T2 signal intensity is considered.
Abbreviations
- ADC
- apparent diffusion coefficient
- AIF
- arterial input function
- a.u.
- arbitrary units
- CBF
- cerebral blood flow
- CBV
- cerebral blood volume
- DIPG
- diffuse intrinsic pontine glioma
- DSC
- dynamic susceptibility-weighted contrast-enhanced perfusion MR imaging
- DTI
- diffusion tensor imaging
- DWI
- diffusion-weighted imaging
- FA
- fractional anisotropy
- GBCA
- gadolinium-based contrast agent
- GM
- gray matter
- rCBF
- relative cerebral blood flow
- rCBV
- relative cerebral blood volume
- rMTT
- relative mean transit time
- T2HOF
- T2 hypointense focus with postcontrast signal enhancement and diffusion restriction
- T2HRT
- typical T2 hyperintense tumor
- WM
- white matter
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