Diffusion-weighted MRI characteristics of the cerebral metastasis to brain boundary predicts patient outcomes

Abstract

BackgroundDiffusion-weighted MRI (DWI) has been used in neurosurgical practice mainly to distinguish cerebral metastases from abscess and glioma. There is evidence from other solid organ cancers and metastases that DWI may be used as a biomarker of prognosis and treatment response. We therefore investigated DWI characteristics of cerebral metastases and their peritumoral region recorded pre-operatively and related these to patient outcomes.MethodsRetrospective analysis of 76 cases operated upon at a single institution with DWI performed pre-operatively at 1.5T. Maps of apparent diffusion coefficient (ADC) were generated using standard protocols. Readings were taken from the tumor, peritumoral region and across the brain-tumor interface. Patient outcomes were overall survival and time to local recurrence.ResultsA minimum ADC greater than 919.4 × 10-6 mm2/s within a metastasis predicted longer overall survival regardless of adjuvant therapies. This was not simply due to differences between the types of primary cancer because the effect was observed even in a subgroup of 36 patients with the same primary, non-small cell lung cancer. The change in diffusion across the tumor border and into peritumoral brain was measured by the “ADC transition coefficient” or ATC and this was more strongly predictive than ADC readings alone. Metastases with a sharp change in diffusion across their border (ATC >0.279) showed shorter overall survival compared to those with a more diffuse edge. The ATC was the only imaging measurement which independently predicted overall survival in multivariate analysis (hazard ratio 0.54, 95% CI 0.3 – 0.97, p = 0.04).ConclusionsDWI demonstrates changes in the tumor, across the tumor edge and in the peritumoral region which may not be visible on conventional MRI and this may be useful in predicting patient outcomes for operated cerebral metastases.

Comparison of diffusion-weighted imaging findings in brain metastases of different origin

“…As suggested by Zakaria et al, not only ADC values of BM but also ADC values of peritumoral region were different in several metastatic lesions [14]. For instance, it has been shown that melanoma metastases had a significantly higher near:far…”

“…According to the literature, ADC values in BM showed a negative correlation with cell density [12,14]. Presumably, BM in SCLC may have a higher cellularity in comparison to BM of other origin.…”

“…The authors suggested that the identified change in diffusion across the brain-metastasis interface might be expected to relate to changes at the cellular level and hence even reflect tumor-stroma interactions [14].…”

Diffusion-Weighted Methods

“…Zakaria et al studied the prognostic value of diffusion parameters in patients with metastases and found that minimum ADC values within the solid enhancing tumors of greater than 919.4 × 10 −6 mm 2 /s, which was the median, indicated longer survival regardless of adjuvant therapies (Zakaria et al 2014). An even better indicator was the ADC transition coefficient from the tumor across the border into the surrounding tissue (1 ROI inside the tumor, 3 ROIs in line outside of the tumor, slope calculation of the linear regression line of ADC values) -tumors with a sharp ADC change across the border (ATC >0.279) correlated with shorter overall survival.…”

Interdisciplinary management of central nervous system metastasis and neoplastic meningitis: recent developments and future perspectives

“…[51] Similarly, pre-operative DW-MRI characteristics of cerebral metastases and their peritumoral region in 76 patients were related to patient outcome. [52] …”