Abstract P324: Your Brain May Be "HOTTER" Than You Think, Results From Phase I Check Brain Temperature Study

Background: Hypothermia is a known neuronal protecting agent and used in post cardiac arrest. However, its use for stroke and brain trauma has not made any progress due to the lack of accurate way of measuring brain temperature. Hence, hypothermic degree and duration for it to be therapeutic is unknown. The phase I Check Brain Temperature Study was to define regional brain temperatures in normal individuals via MRI thermometry. The established brain temperature map can be used as the baseline to provide therapeutic hypothermia. Method: Temperatures of 5 regions of interest (ROI) of brain (frontal lobe, thalamus, hypothalamus, occipital lobe and cerebellum) were measured in 10 healthy individuals by using proton resonance frequency MRI spectroscopy single voxel method. The scanning protocol include a whole brain anatomical images, (3DFSPGR : TR/TE=150/3.9ms, FOV=24cm,matrix=256x256, slice thickness =1 mm.) and spectroscopy PRESS (TR/TE=1500/144 ms, 8 nex, 2 x 2 x 2 cm^3) on a GE 3T scanner. Ten right handed men (18<age<80) were recruited and their oral and tympanic temperatures were monitored. Average whole head temperature=average of oral temp+tympanic temp and average brain temp=average of temp of 5 regions of interest. Two tails, paired t-test used to compare temps between subjects and ROIs. Results: Average temperature differences between brain (38.2 °C) and head (36.5 °C) is 1.8 °C (p< 0.0000002). Thalamus has the highest temperature among all ROIs in brain. Brain temperature > oral temperature > tympanic temperature. Conclusion: Brain temperatures may not correlate to body temperatures and there is a regional difference. Our finding will be used as the baseline brain temperature map when hypothermia is applied in patients with hemisphere stroke in the phase II study.

A thermometry software tool for monitoring laser-induced interstitial thermotherapy

The purpose of this study was to develop a thermometry software tool for temperature monitoring during laser-induced interstitial thermotherapy (LITT). C++ programming language and several libraries including DICOM Toolkit, Grassroots DICOM library, Insight Segmentation and Registration Toolkit, Visualization Toolkit and Quasar Toolkit were used. The software’s graphical user interface creates windows displaying the temperature map and the coagulation extent in the tissue, determined by the magnetic resonance imaging (MRI) thermometry with the echo planar imaging sequence and a numerical simulation based on the radiation and heat transfer in biological tissues, respectively. The software was evaluated applying the MRI-guided LITT to ex vivo pig liver and simultaneously measuring the temperature through a fiber-optic thermometer as reference. Using the software, the temperature distribution determined by the MRI method was compared with the coagulation extent simulation. An agreement was shown between the MRI temperature map and the simulated coagulation extent. Furthermore, the MRI-based and simulated temperatures agreed with the measured one – a correlation coefficient of 0.9993 and 0.9996 was obtained, respectively. The precision of the MRI temperature amounted to 2.4°C. In conclusion, the software tool developed in the present study can be applied for monitoring and controlling the LITT procedure in ex vivo tissues.

Spin crossover iron(ii) complexes as PARACEST MRI thermometers

We demonstrate the potential utility of spin crossover iron(ii) complexes as temperature-responsive paramagnetic chemical exchange saturation transfer (PARACEST) contrast agents in magnetic resonance imaging (MRI) thermometry.