gms | German Medical Science

Objective: Cerebral metastases are the most common brain tumors. Surgery of single cerebral metastases is standard but frequently fails to achieve local tumor control. Although the surgical technique and degree of resection are known to influence local tumor control reliable predictors for local tumor progression and overall survival are unknown. MRI based apparent diffusion coefficients (ADC) are known to correlate with tumor cellularity and invasion and therefore are a substitute for tumor aggression. Few data also showed significant impact of ADC values on outcome. The present pilot study analyzed a potential relation between the MRI based apparent diffusion coefficients (ADC) local recurrence and outcome in patients with brain metastases.

Methods: A retrospective analysis was performed for patients with cerebral metastases and complete surgical resection assessed by an early postoperative MRI < 72h. Follow up to evaluate recurrence was at least 1 year. Minimal ADC (ADCmin) and mean ADC (ADCmean) were assessed in preoperative 1,5T-MRI scans by placing regions of interests in the tumor, the peritumoral tissue and across tumor margins. Results were compared between groups and correlated with local progression free survival (locPFS) and overall survival (OAS).

Results: Analysis of the relation between ADC values, local progression and outcome was performed in 42 patients with a mean age of 59 years (range 33 -78y). Primary site was NSCLC in 19/42 (45%) of all cases. Despite complete resection 13/42 patients (30.9%) suffered from local in-brain-progression. Local PFS was 6.8 months overall survival was 21 months.

There were no significant differences in ADC values in groups based on histology. In the present cohort the mean ADCmin and the mean ADCmean within the metastasis did not significantly differ between patients with and without a later local in-brain progression (667x10-6 vs. 754x10-6 mm2/s and 1189x10-6 vs. 1403x10-6 mm­­­­2/s; each p > 0.05). No significant differences in the ADCmean in the peritumoral region as well as across the tumor margins were found in patients with and without a later local recurrence (each, p > 0.05). Mean ADC values did not correlate significantly with PFS and OAS and there were no differences in groups based on mean ADCmin and mean ADCmean.

Conclusion: In the present pilot cohort analysed ADC values had no significant impact on the local in-brain-progression, locPFS and OAS.