Apparent Diffusion Coefficiency For Evaluation Of The Response Of Brain Tumors Treated By Gamma Knife Surgery

Chuan-Fu Huang1, Shyh-Ying Chiou2, Hsien-Tang Tu2, Jim-Chao Chuang2, Long-Yau Lin2

1Taichung , Taiwan, Province Of China 2Chung Shan Medical University Hospital, Taichung, Taiwan.

Keywords: gamma knife, brain metastasis, brain tumor, Imaging, outcome

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     Cellular density is the major factor of apparent diffusion constant (ADC) change.
     We hypothesized loss of tumor cells after Gamma Knife surgery (GKS) might alter ADC and utilized diffusion MRI to evaluate cellular changes in brain tumors to detect response and efficacy.
     We conducted a prospective trial involving 86 patients with 38 solid or solid-dominated brain metastases, 26 meningiomas and 22 acoustic neuromas treated by GKS.
     Patients received serial MRI examination including diffusion weighted imaging (DWI) before treatment and at multiple intervals following GKS. We followed up MRI findings and clinical outcomes at 3 months interval for metastases and 6 months intervals for benign tumors. We calculated apparent diffusion coefficients (ADC) at each follow-up.
       The ADC for meningioma was 0.82 ± 0.15 ´10-3 mm2/s (range 0.75-0.93 ´10-3 mm2/s).. The mean ADC values for all meningiomas treated at last mean follow-up 3.5 years (range, 1-6 years) were 1.36 ± 0.19 ´10-3 mm2/s, and these values were significantly (P<0.0001)increased when compared with values before SRS. Calcification, radiation necrosis and recurrence of tumor tended to prevent the rise of ADC level. 
     This is a retrospective study.
     The ADC values might be useful to evaluate treatment results.—
     Also, in some patients the ADC values are useful to distinguish radiation-induced central necrosis from tumor regrowth in cases where other imagery is not definitive.


Project Roles:

C. Huang (), S. Chiou (), H. Tu (), J. Chuang (), L. Lin ()