Augusto Elias Mamere MD, Presenter: Nothing to Disclose

Renato Jose Affonso MD, Abstract Co-Author: Nothing to Disclose

Leonir Terezinha Feltrin MD, Abstract Co-Author: Nothing to Disclose

Andre Lopes Carvalho MD, PhD, Abstract Co-Author: Nothing to Disclose

Stela Verzinhasse Peres PhD, Abstract Co-Author: Nothing to Disclose

Antonio Carlos Dos Santos MD, PhD, Abstract Co-Author: Nothing to Disclose

Whole brain radiation therapy (WBRT) has long been used in the treatment of brain metastases. Patients with brain metastases may not achieve maximum benefit from WBRT due to tumor hypoxia, which decreases radiation sensitivity. Tumor oxygenation is directly related to vessel density inside the tumor. Perfusion magnetic resonance imaging (MRI) using dynamic susceptibility contrast-enhanced (DSC) technique can noninvasively estimate brain tumor microvessel density. The purpose of this study is to assess if pretherapeutic relative blood volume (rCBV) and flow (rCBF) measurements would help to predict brain metastases response to WBRT.

25 patients (23 – 67 years; mean age = 50.8; 9 men) with brain metastases who received standard WBRT (30 Gy) were included. Baseline MR scan was performed up to 1 week before treatment started. Follow-up scans were performed 1 and 3 months after the end of therapy. One measurable nodule (diameter ≥ 10 mm) was selected for measurement and follow-up. rCBV and rCBF values were obtained from regions of interests (ROIs) placed on the site of the maps which best corresponded to the enhanced regions of the nodule. The nodule response was categorized according to standard World Health Organization (WHO) criteria. Patients were divided in two groups: respondent (complete or a partial response) and non-respondent (disease progression or stable disease).

The primary tumors were: lung, in 11 patients; breast, in 6; melanoma, in 4; gastrointestinal tract, in 3; and ovary, in 1. Pretreatment rCBV and rCBF mean values were 6.33 ± 2.84 and 5.24 ± 2.05 in the respondent group, and 3.03 ± 2.13 and 2.77 ± 3.05 in the non-respondent group (t test: p<.05). ROC curve analysis for pretreatment rCBV and rCBF showed area under the curve of 0.870 ± 0.072 and 0.896 ± 0.064, respectively. The optimal cutoff values for differentiating respondent and non-respondent patients were 3.69 (sensitivity, 92.8%; specificity, 81.8%) for rCBV, and 2.45 (sensitivity, 100%; specificity, 81.8%) for rCBF.

These preliminary data provide evidence that pretreatment DSC perfusion MRI with rCBV and rCBF measurement may potentially predict brain metastases response to palliative WBRT.

Perfusion MRI with rCBV and rCBF measurement may potentially predict brain metastases response to palliative whole brain radiation therapy, but further studies are necessary.

Mamere, A, Affonso, R, Feltrin, L, Carvalho, A, Peres, S, Carlos Dos Santos, A, Pretreatment Dynamic Contrast-enhanced Perfusion MR Imaging for Assessment of Brain Metastases Response to Palliative Whole Brain Radiation Therapy.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8003605.html