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Preoperative grading of presumptive low-grade astrocytomas on MR imaging: diagnostic value of minimum apparent
1Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada.
Background And Purpose:
Histopathologic grade of glial tumors is inversely correlated with the minimum apparent diffusion coefficient (ADC). We assessed the diagnostic values of minimum ADC for preoperative grading of supratentorial astrocytomas that were diagnosed as low-grade astrocytomas on conventional MR imaging.
Materials And Methods:
Among 118 patients with astrocytomas (WHO grades II-IV), 16 who showed typical MR imaging findings of low-grade supratentorial astrocytomas on conventional MR imaging were included. All 16 patients underwent preoperative MR imaging and diffusion-weighted imaging. The minimum ADC value of each tumor was determined from several regions of interest in the tumor on ADC maps. To assess the relationship between the minimum ADC and tumor grade, we performed the Mann-Whitney U test. A receiver operating characteristic (ROC) analysis was used to determine the cutoff value of the minimum ADC that had the best combination of sensitivity and specificity for distinguishing low- and high-grade astrocytomas.
Results:
Eight of the 16 patients (50%) were confirmed as having high-grade astrocytomas (WHO grades III and IV), and the other 8 patients were confirmed as having low-grade astrocytomas (WHO grade II). The median minimum ADC of the high-grade astrocytoma (1.035 x 10(-3) mm(2) . sec(-1)) group was significantly lower than that of the low-grade astrocytoma group (1.19 x 10(-3) mm(2) . sec(-1)) (P = .021). According to the ROC analysis, the cutoff value of 1.055 x 10(-3) mm(2) . sec(-1) for the minimum ADC generated the best combination of sensitivity (87.5%) and specificity (79%) (P = .021).
Conclusion:
Measuring minimum ADC can provide valuable diagnostic information for the preoperative grading of presumptive low-grade supratentorial astrocytomas.
Insights
Minimum apparent diffusion coefficient (ADC) effectively differentiates low-grade from high-grade astrocytomas. This imaging metric aids in preoperative grading of supratentorial tumors, improving diagnostic accuracy.
Area of Science:
- Neuroradiology
- Oncology
- Medical Imaging
Background:
- Histopathologic grade of glial tumors correlates inversely with minimum apparent diffusion coefficient (ADC).
- Conventional MRI may misdiagnose low-grade astrocytomas.
Purpose of the Study:
- Assess diagnostic value of minimum ADC for preoperative grading of supratentorial astrocytomas.
- Distinguish between low- and high-grade astrocytomas initially diagnosed as low-grade.
Main Methods:
- Included 16 patients with astrocytomas (WHO grades II-IV) showing low-grade features on conventional MRI.
- Determined minimum ADC values from ADC maps using regions of interest.
- Utilized Mann-Whitney U test and Receiver Operating Characteristic (ROC) analysis for grading assessment.
Main Results:
- 50% of patients (8/16) had high-grade astrocytomas (WHO III-IV), while 50% had low-grade (WHO II).
- Median minimum ADC was significantly lower in high-grade (1.035 x 10(-3) mm(2)/sec) versus low-grade (1.19 x 10(-3) mm(2)/sec) astrocytomas (P=.021).
- ROC analysis identified a minimum ADC cutoff of 1.055 x 10(-3) mm(2)/sec with 87.5% sensitivity and 79% specificity (P=.021).
Conclusions:
- Minimum ADC measurement provides valuable diagnostic information.
- This metric aids in the preoperative grading of presumed low-grade supratentorial astrocytomas.
- Enhances diagnostic accuracy in differentiating tumor grades.
