|Paper title||Diffusion imaging of treated and untreated meningiomas - a follow-up study|
|Form of presentation||Poster|
INTRODUCTION: A non-invasive method to predict treatment outcome of meningiomas would be desirable to improve tumor management. Previous studies have shown that pre-treatment apparent diffusion coefficient (ADC) values can predict treatment response in brain tumors. To analyze whether intra-tumoral ADC values change due to treatment over time untreated and treated meningiomas were compared.
METHODS: MRI examinations of 64 patients with suspected or histologically confirmed meningiomas were retrospectively reviewed. This series included 28 untreated patients and 36 treated (n=10 partial resected; n=26 radiosurgery) patients. The follow-up time period ranged between 1-10 years. Comparing ADC with T1-weighted sequences a region-of-interest (ROI) was placed within tumor margins avoiding the surrounding normal brain. A ROI was then set on the adjacent slice above and below, if the tumor was large enough using PMOD Software. The ADC values of these three ROIs were then averaged and statistically compared using SPSS Statistics v24.
RESULTS: Baseline ADC values before treatment were similar in treated and untreated meningiomas. The mean ADC values, ADC10%min and ADC90%max within the different groups did not show significant changes during the follow-up in untreated (over 10 years period: 0.87±0.05x10-3 mm2/s), partially resected (over 10 years period: 1.01±0.07x10-3 mm2/s) and radiosurgically treated (over 4 years period: 1.02±0.12x10-3 mm2/s) groups. However, a significant difference was observed between the mean ADC and ADC90%max values of untreated and partially resected (p<0.0001) and respectively radiosurgically treated (p<0.0001) meningiomas. Also, ADC10%min revealed statistically significant difference between untreated and radiosurgery group (p<0.05) as well as between untreated and partially resected meningiomas (p<0.001).
CONCLUSION: ADC values in conservatively managed meningiomas remain stable during the follow-up. However, treated meningiomas reveal significant change of the mean ADC values over time, suggesting that ADC may reflect a change in the biological behavior of the tumor.