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Glioma grading: sensitivity, specificity, and predictive values of perfusion MR imaging and proton MR spectroscopic
Meng Law1, Stanley Yang, Hao Wang
1Department of Radiology, New York University Medical Center, NY, USA.
Background And Purpose:
Sensitivity, positive predictive value (PPV), and negative predictive value (NPV) of conventional MR imaging in predicting glioma grade are not high. Relative cerebral blood volume (rCBV) measurements derived from perfusion MR imaging and metabolite ratios from proton MR spectroscopy are useful in predicting glioma grade. We evaluated the sensitivity, specificity, PPV, and NPV of perfusion MR imaging and MR spectroscopy compared with conventional MR imaging in grading primary gliomas.
Methods:
One hundred sixty patients with a primary cerebral glioma underwent conventional MR imaging, dynamic contrast-enhanced T2*-weighted perfusion MR imaging, and proton MR spectroscopy. Gliomas were graded as low or high based on conventional MR imaging findings. The rCBV measurements were obtained from regions of maximum perfusion. Metabolite ratios (choline [Cho]/creatine [Cr], Cho/N-acetylaspartate [NAA], and NAA/Cr) were measured at a TE of 144 ms. Tumor grade determined with the three methods was then compared with that from histopathologic grading. Logistic regression and receiver operating characteristic analyses were performed to determine optimum thresholds for tumor grading. Sensitivity, specificity, PPV, and NPV for identifying high-grade gliomas were also calculated.
Results:
Sensitivity, specificity, PPV, and NPV for determining a high-grade glioma with conventional MR imaging were 72.5%, 65.0%, 86.1%, and 44.1%, respectively. Statistical analysis demonstrated a threshold value of 1.75 for rCBV to provide sensitivity, specificity, PPV, and NPV of 95.0%, 57.5%, 87.0%, and 79.3%, respectively. Threshold values of 1.08 and 1.56 for Cho/Cr and 0.75 and 1.60 for Cho/NAA provided the minimum C2 and C1 errors, respectively, for determining a high-grade glioma. The combination of rCBV, Cho/Cr, and Cho/NAA resulted in sensitivity, specificity, PPV, and NPV of 93.3%, 60.0%, 87.5%, and 75.0%, respectively. Significant differences were noted in the rCBV and Cho/Cr, Cho/NAA, and NAA/Cr ratios between low- and high-grade gliomas (P <.0001,.0121,.001, and.0038, respectively).
Conclusion:
The rCBV measurements and metabolite ratios both individually and in combination can increase the sensitivity and PPV when compared with conventional MR imaging alone in determining glioma grade. The rCBV measurements had the most superior diagnostic performance (either with or without metabolite ratios) in predicting glioma grade. Threshold values can be used in a clinical setting to evaluate tumors preoperatively for histologic grade and provide a means for guiding treatment and predicting postoperative patient outcome.
Insights
Perfusion MR imaging (relative cerebral blood volume) and MR spectroscopy (metabolite ratios) significantly improve glioma grading accuracy compared to conventional MR imaging alone. These advanced techniques offer superior diagnostic performance for predicting tumor grade and guiding treatment.
Area of Science:
- Neuroimaging
- Oncology
- Radiology
Background:
- Conventional MRI has limited accuracy in predicting glioma grade.
- Perfusion MRI (rCBV) and MR spectroscopy (metabolite ratios) show promise for glioma grading.
Purpose of the Study:
- To evaluate the sensitivity, specificity, PPV, and NPV of perfusion MRI and MR spectroscopy for grading primary gliomas.
- To compare the diagnostic performance of these advanced techniques against conventional MRI.
Main Methods:
- 160 patients with primary gliomas underwent conventional MRI, perfusion MRI (rCBV), and proton MR spectroscopy (metabolite ratios: Cho/Cr, Cho/NAA, NAA/Cr).
- Tumor grade was compared with histopathology.
- Logistic regression and ROC analyses determined optimal thresholds for grading.
Main Results:
- Conventional MRI showed 72.5% sensitivity and 65.0% specificity for high-grade gliomas.
- rCBV (threshold 1.75) achieved 95.0% sensitivity and 57.5% specificity.
- Combined rCBV and metabolite ratios yielded 93.3% sensitivity and 60.0% specificity.
Conclusions:
- Perfusion MRI (rCBV) and MR spectroscopy (metabolite ratios) significantly enhance glioma grading accuracy.
- rCBV measurements demonstrate superior diagnostic performance, individually and in combination with metabolite ratios.
- Established thresholds can guide preoperative grading, treatment decisions, and outcome prediction.
