Can Average Value of Apparent Diffusion Coefficient (ADC) from Magnetic Resonance Images Predict Consistency of Intracranial Meningioma?
Siriwut Pokanan MD*, Lojana Tuntiyatorn MD**, Noppadol Larbchareonsub MD***, Sasivimon Mongkolsukpaiboon MD****, Ake Hansasuta MD*
Affiliation : * Division of Neurosurgery, Department of Surgery, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand ** Department of Radiology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand *** Department of Pathology, Faculty of Medicine Ramathibodi Hospital, Mahidol University, Bangkok, Thailand **** Division of Neurosurgery, Sirindhorn Hospital, Bangkok Metropolitan Administration, Bangkok, Thailand
Background : Surgery for intracranial meningioma is either relatively simple or extremely difficult based heavily on tumor
consistency.
Objective : To examine the average diffusion constant from apparent diffusion coefficient (ADC), acquired from routine
magnetic resonance imaging (MRI), whether it can reliably predict consistency of intracranial meningioma. The secondary
objective is to find out if tumor consistency correlate with its histopathology.
Material and Method: Prospectively collected data between July 2009 and July 2011, including demographic, radiographic,
intra-operative findings, and histopathology, was evaluated. Eligible patients must have had pre-operative conventional MRI
obtained at Faculty of Medicine Ramathibodi Hospital, with calculated average diffusion constant from ADC. All of the
included patients’ meningioma resection as well as histopathology were performed at our institute. During each surgical
resection, unaware of the MRI interpretation, the operating neurosurgeon classified each meningioma as having soft, firm, or
hard consistency. Pathology of 2007 WHO grade I vs. II, tumors was independently reported by neuropathologist without
knowledge of pre-operative radiographic and intra-operative tumor consistency.
Results : Fifty-eight patients with intracranial meningioma met the inclusion criteria. The average ADC values amongst soft,
firm, and hard consistency tumors were not statistically different (p = 0.82). As for WHO grades, neither the T2 weighted
images (T2W) intensity nor the average ADC value showed differences between grade I and grade II meningioma (p = 0.84
and p = 0.31 respectively). The only significant correlation was observed between hyperintensity signal on T2W and high
proportion of soft consistency tumors (p = 0.001). In addition, meningiomas with soft consistency were more commonly
associated with WHO grade II histopathology (p = 0.01).
Conclusion : Although theoretically sound, average ADC did not reliably predict consistency of intracranial meningioma.
Nevertheless, tumors with soft consistency often exhibited hyperintensity signal on T2W and were frequently associated with
WHO grade II. This adds to prior studies reiterating similar findings. Neurosurgeons should utilize such information to
prepare well before performing intracranial meningioma surgery.
Keywords : Meningioma, MRI, Consistency, DWI, Apparent diffusion coefficient, ADC, T2W
