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High-grade and low-grade gliomas: differentiation by
using perfusion MR imaging
Hakyemez B, Erdogan C, Ercan I, Ergin N, Uysal S, Atahan S
Department of Radiology, BURTOM Radioimaging Center, Bursa, Turkey.
Aim. Relative cerebral blood volume (rCBV) is a commonly used perfusion
magnetic resonance imaging (MRI) technique for the evaluation of tumour
grade.
Relative cerebral blood flow (rCBF) has been less studied.
The goal
of our study was to determine the usefulness of these parameters in
evaluating the histopathological grade of the cerebral gliomas.
Methods.
This study involved 33 patients (22 high-grade and 11 low-grade glioma
cases).
MRI was performed for all tumours by using a first-passage
gadopentetate dimeglumine T2*-weighted gradient-echo single-shot echo-planar
sequence followed by conventional MRI.
The rCBV and rCBF were calculated by
deconvolution of an arterial input function.
The rCBV and rCBF ratios of the
lesions were obtained by dividing the values obtained from the normal white
matter of the contralateral hemisphere.
For statistical analysis
Mann-Whitney testing was carried out.
A p value of less than 0.05 indicated
a statistically significant difference.
Receiver operating characteristic
curve (ROC) analysis was performed to assess the relationship between the
rCBV and rCBF ratios and grade of gliomas.
Their cut-off value permitting
discrimination was calculated.
The correlation between rCBV and CBF ratios
and glioma grade was assessed using Pearson correlation analysis.
Results.
In high-grade gliomas, rCBV and rCBF ratios were measured as 6.50+/-4.29 and
3.32+/-1.87 (mean+/-SD), respectively.
In low-grade gliomas, rCBV and rCBF
ratios were 1.69+/-0.51 and 1.16+/-0.38, respectively.
The rCBV and rCBF
ratios for high-grade gliomas were statistically different from those of
low-grade gliomas (p<0.001).
The rCBV and CBF ratios were significantly
matched with respect to grade, but difference between the two areas was not
significant (ROC analysis, p>0.05).
The cut-off value was taken as 1.98
in the rCBV ratio and 1.25 in the rCBF ratio.
There was a strong correlation
between the rCBV and CBF ratios (Pearson correlation=0.830, p<0.05).
Conclusion. Perfusion MRI is useful in the preoperative assessment of the
histopathologicalal grade of gliomas; the rCBF ratio in addition to the rCBV
ratio can be incorporated in MR perfusion analysis for the evaluation.
PMID: 15767107 [PubMed - in process]
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