Amir Kasra Iranmahboob MS, Presenter: Nothing to Disclose

Kyung K. Peck PhD, Abstract Co-Author: Nothing to Disclose

Bob Hou PhD, Abstract Co-Author: Nothing to Disclose

Andrei I. Holodny MD, Abstract Co-Author: Nothing to Disclose

The normal vasodilation due to increased CO2 during breath holding (BH) is muted in brain tumor patients due to abnormal neovasculature. We used the BOLD mechanism during breath holding to quantify differences in vascular reactivity in high grade gliomas.

7 patients with high-grade glioma were evaluated using BH MRI acquired in GE 1.5T scanner (GRE EPI, TR/TE= 4000ms/ 35ms, 128x128 matrix, 4.5mm thickness). Paradigm was 4 sec of a single deep breath followed by 16 sec of BH and 40 sec of regular breathing for 6 cycles. Data was analyzed by AFNI. “Peak-to-trough” was defined as the difference between minimal signal seen at the end of the deep breath and the maximal signal seen at the end of BH. A vascular reactivity map was generated using the peak-to-trough and MATLAB. Vascular reactivity was quantitatively compared using: 1) segmentation of gray and white matter performed using FSL and 2) ROI’s of tumor area and the normal contralateral hemisphere generated by a neuroradiologist. Mean squared error (MSE) was used as a measure of variability of the BH curve over time. The vascular reactivity maps were compared subjectively to the routine MRI.

In normal brain, white matter (mean±SD = 17.8±7.6 A.U.) showed a smaller peak-to-trough difference than grey matter (41.6±26.2 A.U.), reflecting a smaller vascular reactivity (p<0.009). The peak-to-trough difference was also significantly less in the tumor (21.1±23.5 A.U.) ROI than the contralateral normal (31.7±28.48 A.U.) side ROI reflecting a decrease in vascular reactivity (p<0.007) of the abnormal tumor neovasculature. The localization of the tumor was evident in the vascular reactivity map. MSE was greater for the tumor side but did not reach statistical significance (p=0.14). Subjectively, the vascular reactivity maps only moderately correlated to Gd-enhancement. In 2 cases a prominent decrease in vascular reactivity was seen in non-enhancing tumors.

BH BOLD maps can accurately characterize vascular reactivity in brain tumors which significantly differs from the normal contralateral brain. The variability of the BH signal over time is also greater in brain tumors, although this did not reach statistical significance in this small number of patients.

Vascular reactivity maps based on BH are robust, reliable and easily obtained in patients with brain tumors and may prove useful in therapies which affect enhancement.

Iranmahboob, A, Peck, K, Hou, B, Holodny, A, Vascular Reactivity Measurements Using Breath-holding BOLD MR in Patients with Brain Tumors.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9011245.html