Comparison of multiple parameters obtained on 3T pulsed arterial spin-labeling, diffusion tensor imaging, and MRS and the Ki-67 labeling index in evaluating glioma grading

Abstract

Background and purpose: Pulsed arterial spin-labeling, DTI, and MR spectroscopy provide useful data for tumor evaluation. We evaluated multiple parameters by using these pulse sequences and the Ki-67 labeling index in newly diagnosed supratentorial gliomas.

Materials and methods: All 32 patients, with grade II (3 each of diffuse astrocytoma, oligodendroglioma, and oligoastrocytoma), grade III (3 anaplastic astrocytomas, 4 anaplastic oligodendrogliomas, and 1 anaplastic oligoastrocytoma), and grade IV (14 glioblastomas and 1 glioblastoma with an oligodendroglioma component) cases underwent pulsed arterial spin-labeling, DTI, and MR spectroscopy studies by using 3T MR imaging. The following variables were used to compare the tumors: relative cerebral blood flow, fractional anisotropy; ADC tumor/normal ratios; and the Cho/Cr, NAA/Cho, NAA/Cr, and lactate/Cr ratios. A logistic regression and receiver operating characteristic analysis were used to assess parameters with a high sensitivity and specificity to identify the threshold values for separate grading. We compared the Ki-67 index with various MR imaging parameters in tumor specimens.

Results: Significant correlations were observed between the Ki-67 index and the mean, maximum, and minimum ADC, Cho/Cr, and lactate/Cr ratios. The receiver operating characteristic analysis showed that the combination of the minimum ADC and Cho/Cr ratios could differentiate low-grade and high-grade gliomas, with a sensitivity and specificity of 87.0% and 88.9%, respectively. The mean and maximum relative cerebral blood flow ratios were used to classify glioblastomas from other-grade astrocytomas, with a sensitivity and specificity of 92.9% and 83.3%, respectively.

Conclusions: Our findings indicate that pulsed arterial spin-labeling, DTI, and MR spectroscopy are useful for predicting glioma grade. Additionally, the parameters obtained on DTI and MR spectroscopy closely correlated with the proliferative potential of gliomas.

Fig 1.

A 62-year-old man with a grade II oligoastrocytoma. The contrast-enhanced T1-weighted image shows a nonenhancing mass in the right hippocampus (A). The lesions presented high-intensity signals on FLAIR images (B). The rCBF map on PASL shows no areas of hyperperfusion (C). The FA map shows low FA values (D). The ADC map shows increased tumor diffusion values (E). The tumor MR spectrum shows decreased NAA and slightly increased Cho and Lac (F). The Ki-67 labeling index is 5.0% (original magnification × 400) (G).

Fig 2.

A 60-year-old woman with a grade IV glioblastoma. The lesion on the left frontotemporal lobe exhibits strong enhancement on gadolinium T1-weighted image (A). The neoplasm is clearly hyperperfused compared with the healthy parenchyma on the PASL image (B). The FA map shows slightly low FA values (C). The ADC map shows heterogeneous tumor diffusion values (D). The tumor MR spectrum shows decreased NAA with a marked increase in Cho and Lac (E). The Ki-67 labeling index is 27.0% (original magnification × 400) (F).