High density flexible coil arrays for improved SNR in prostate MRI
High density flexible coil arrays for improved SNR in prostate MRI
SJ Riederer, EA Borisch, AT Froemming, TC Hulshizer, A Kawashima, KP McGee, F Robb, PJ Rossman, N Takahashi
An unexploited characteristic of AIR Coil technology is the low mutual inductance, allowing increased element overlap and thus an increased number of elements sensitized to a given volume. The purpose was to develop and evaluate coil arrays which have high (>40%) overlap of elements for improved SNR in prostate MRI.
The 20 10-cm diameter elements of an anterior array and 21 12-cm elements of a posterior array were reconfigured to have 45% coil-to-coil overlap vs. the standard 20%. The modified anterior array is shown in Figure 1. Performance of the modified array was compared with the commercially available anterior blanket and posterior in-table arrays using T2-weighted spin-echo (T2SE) acquisition (16cm FOV, 0.50x0.56mm2 inplane resolution; 84 3mm thick overlapped slices, 4:40 acq time). For ten prostate MRI exams the axial T2SE series of each array were compared blindly using a five-point relative scale by three experienced uroradiologists for relative SNR and sharpness.
Modified coil array with highly overlapped elements
The new 41-element array combination provided 15% increased SNR in a humanoid phantom. For all 30 evaluations of the human studies the new array combination was rated as providing improved SNR (Figure 2). Sharpness improvement was also significant (Figure 3). Representative results are shown in Figures 4-6.
Results of evaluation of SNR showing consistent improvement with high density array.
Results of evaluation of shaprness showing consistent improvement with high density array.
Results from Study #5 showing general improved SNR using new array (right).
The increased overlap of individual coil elements allowed by low inductance AIR coil technology provides an SNR gain over conventional coil arrays. The array combination may also be useful in other MRI studies of the pelvis.
Results from Study #6 showing general improved conspicuity of suspect hypointense lesion using new array (right).
Results from Study #7 showing improved sharpness using new array (right).
