Article Figures & Data
Figures
- FIG 1.
Different positions of the infant model in the radiofrequency coil. On the left, the adult head and torso are shown. They are used as a reference.
- FIG 2.
Setup for measuring acoustic noise at the MR imaging table in the presence of the hood. This test setup consisted of a dummy bore with dimensions similar to those of the 7T MR system with a 10-mm plastic plate of polyoxymethylene to create an MR imaging table. The speakers producing the sound are positioned at 28-cm distance around the dummy bore to mimic the sound produced by the MR imaging scanner.
- FIG 3.
Local SAR levels in adult head (left) and Charlie in the different coil positions. Shifts of an infant in the x and y directions are unlikely because of limited space; therefore, the results are not included in the figure. The SAR values when infant Charlie is positioned 50 mm in the x or y direction are comparable with those in the +50-mm FH position.
- FIG 4.
Examples of images of different patients at 3T (upper row) versus 7T MR imaging (lower row). A and G , MRV at 3T and 7T, respectively, of a preterm infant at term-equivalent age. B and H, An SWI at, respectively, 3T and 7T of a preterm infant at term-equivalent age. C and I, The 6-week follow-up single-shot T2-weighted image of a term-born infant with a perinatal stroke. The arrows indicate perivascular spaces that were better visualized at 3T compared with 7T. D and J, A 3-month follow-up MRA at 3T and 7T of a term-born infant with an occipital stroke. E and K, T1WI (MPRAGE) of a preterm-born infant at term-equivalent age. F and L, An MR spectroscopy spectrum at 3T and 7T of a preterm infant at term-equivalent age, both with a comparable ROI in the left basal ganglia/thalami region.
Tables
Duke Centered Ella Centered Charlie Centered Charlie −50-mm FH Charlie +50-mm FH Global SAR levels Average SAR for 1 Watt input power (W kg−1) 0.066 0.069 0.062 0.050 0.075 Average SAR per B12 (W kg−1 µT–2) 0.462 0.465 0.289 0.454 0.474 Average B1+ in central section for 1 Watt input power (µT)a 0.379 0.385 0.466 0.333 0.398 Peak local SAR levels Peak local SAR (10-g averaged) for 1 Watt input power (W kg−1) 0.435 0.398 0.321 0.213 0.487 Peak local SAR (10-g averaged) per B12 (W kg−1µT–2) 3.04 2.63 1.48 1.92 3.08 ↵a The power optimization procedure of the MR imaging scanner software calibrates the needed input power to achieve a certain B1 in the subject. This calibration is based on the average B1+ in a central section of the subject (brain in this case).
- Table 2:
Acoustic noise levels in decibel(A), with use of no hood, the 3T hood, and the newly developed 7T hood
Both Ends of the Bore Sides of the Bore Sides and Ends of the Bore No hood for acoustic noise protection 60.0 dB(A) 58.5 dB(A) 62.5 dB(A) 3T Nordell hood for acoustic noise protection 54.0 dB(A) 51.0 dB(A) 55.5 dB(A) Prototype 7T hood for acoustic noise protection 54.0 dB(A) 43.0 dB(A) 54.0 dB(A)
