Kim Annink

224 Chapter 10 Table 1: Continued Characteristic Normothermic (n=29) Hypothermia (n=7) Timing temperature before start MRI in hours, median (IQR) -1.0 (-1.0 – -1.0) 0.0 (-1.0 – 0.0) Temperature measured with continuous rectal temperature monitor, n (%) 25 (86.2) 7 (100.0) Peripheral Temperature after MRI in ˚C, median (IQR) 36.5 (36.2 – 36.8) 33.4 (32.8 – 35.0) Timing temperature after start of MRI in hours, median (IQR) 2.0 (2.0 – 2.0) 3.0 (2.0 – 3.0) Temperature measured with continuous rectal temperature monitor, n (%) 21 (72.4) 7 (100.0) Short TE 1 H-MRS available, n (%) 20 (68.9) 5 (71.4) Long TE 1 H-MRS available, n (%) 25 (86.2) 6 (85.7) Calibration First of all, the phantom was used to calculate a calibrated formula for our scanner. Figure 2 shows the actual temperatures of the phantom plotted against the ΔH 2 O-NAA. The following formula is calculated based on these data: T=263-(ΔH 2 O- NAA*85.76), in which T is the temperature and ΔH 2 O-NAA is the chemical shift between NAA and H 2 O in ppm. The r 2 of this curve was 0.96. Figure 2: Phantom calibration. The temperatures of the phantom are plotted against the chemical shift difference (ΔH 2 O-NAA) to calculate the calibrated formula.