Yi Tang MD, PhD, Presenter: Nothing to Disclose

Sathish Kumar Dundamadappa MD, Abstract Co-Author: Nothing to Disclose

Senthur Thangasamy MD, Abstract Co-Author: Nothing to Disclose

Thomas Flood MD, PhD, Abstract Co-Author: Nothing to Disclose

Keith Cauley MD, PhD, Abstract Co-Author: Nothing to Disclose

Deepak Takhtani MD, Abstract Co-Author: Nothing to Disclose

Benign meningiomas have a lower postsurgical recurrence rate in comparison with aggressive meningiomas. The Ki-67 proliferation index (PI) is known marker of tumor proliferation and a value of 4 has been associated with aggressive tumors. The apparent diffusion coefficient (ADC) is used to quantify cellularity of the tumors. Our goal was to see: 1) if there is a statistically significant correlation between ADC and Ki-67 PI in low grade meningiomas; and 2) if the ADC values can help stratify low grade meningiomas and predict their recurrence.

Materials and Methods: MRI exams and histopathology of forty-six surgically treated low-grade meningioma patients (WHO grade I) were retrospectively reviewed. All MRI examinations were performed on 1.5-T clinical scanners. Mean ADC values were calculated on ADC maps derived from diffusion MR Imaging. Correlation coefficients were calculated for mean ADC and Ki-67 PI values using linear regression. An independent unpaired Student’s t test was used to compare the ADC in low Ki-67 PI group (<3%) and high Ki-67 PI group ( ≥ 3%).

Results: There is inverse relationship between ADC value and Ki-67 PI measurements in low-grade meningiomas (r=-0.22), but no statistical significance was found (p>0.05). Nine cases (19.8%) had high Ki-67 PI (mean 4.9±2.0%) and 37 cases had low Ki-67 PI (mean 1.4±1.2%). The mean ADC value in high Ki-67 PI group (0.73± 0.04 x10-3 mm2/s) is significantly lower than those with low Ki-67 PI (mean ADC 0.85± 0.13 x10-3 mm2/s) (p=0.01).

Conclusion: The ADC values in low-grade meningiomas with higher Ki-67 PI are significantly lower than those with low Ki-67 PI. Thus, low ADC values in low-grade meningioma could suggest a higher risk of recurrence.

Clinical relevance/applications: Low ADC values in low-grade meningioma could suggest a higher risk of recurrence, therefore increased post-surgical surveillance in low-grade meningiomas with low ADC

Tang, Y, Dundamadappa, S, Thangasamy, S, Flood, T, Cauley, K, Takhtani, D, Relationship of ADC Values and Ki-67 Proliferation Index in Low-grade Meningiomas.  Radiological Society of North America 2013 Scientific Assembly and Annual Meeting, December 1 - December 6, 2013 ,Chicago IL. http://archive.rsna.org/2013/13026016.html