Automatic Deactivation in Phased Array Probe for Human Prostate Magnetic Resonance Imaging at 1.5T

A four element prototype phased array surface probe has been designed and constructed to improve clinical human prostate spectroscopic data. The probe consists of two pairs of adjacent rectangular coils with an optimum overlap to reduce the mutual inductance. The two pairs are positioned on the anterior and the posterior pelvic region and two couples of varactors at the input of each coil undertake the procedures of tuning and matching. The probe switches off and on automatically during the consecutive phases of the MR experiment with the use of an analog switch that is triggered by a microcontroller. Experimental tests that were carried out resulted in high levels of tuning accuracy. Also, the switching mechanism functions properly for various applied loads and pulse sequence characteristics, producing only 10 μs of latency.

Authors:

• Fotios N. Vlachos
• Anastasios D. Garetsos
• Nikolaos K. Uzunoglu
• Efstathios D. Gotsis

Keywords:

• Automatic tuning
• prostate imaging
• phased array
• spectroscopy.

References:

[1] D. J. Gilderdale, N. M. DeSouza, G. A. Coutts, M. K. Chui, D. J.
Larkman, A. D. Williams, and I. R. Young, "Design and use of internal
receiver coils for magnetic resonance imaging," The British Journal of
Radiology, vol. 72, pp. 1141-1151, 1999.
[2] A. C. Yung, A. Y. Oner, J-M. Serfaty, M. Feneley, X. Yang, and E.
Atalar, "Phased-Array MRI of Canine Prostate Using Endorectal and
Endourethral Coils," Magnetic Resonance in Medicine, vol. 49, pp. 710-
715, 2003.
[3] S. M. Wright, and L. L. Wald , "Theory and Application of Array Coils
in MR Spectroscopy," NMR in Biomedicine, vol. 10, pp. 394-410, 1997.
[4] F. V. Coakley, J. Kurhanewicz, Y. Lu, K. D. Jones, M. G. Swanson, S.
D. Chang, P. R. Carroll, and H. H. Hricak, "Prostate Cancer Tumor
Volume: Measurement with Endorectal MR and MR Spectroscopic
Imaging," Radiology, vol. 223, pp. 91-97, 2002.
[5] J. Scheidler, H. Hricak, D. B. Vigneron, K. K. Yu, D. L. Sokolov, L. R.
Huang, C. J. Zaloudek, S. J. Nelson, P. R. Carroll, and J. Kurhanewicz,
"Prostate Cancer: Localization with Three-dimensional Proton MR
Spectroscopic Imaging - Clinicopathologic Study," Radiology, vol. 213,
pp. 473-480, 1999.
[6] R. Pérez de Alejo, C. Garrido, P. Villa, I. Rodriguez, J. J. Vaquero, J.
Ruiz-Cabello, and M. Cortijo, "Automatic Tuning and Matching of a
Small Multifrequency Saddle Coil at 4.7T," Magnetic Resonance in
Medicine, vol. 51, pp. 869-873, 2004.
[7] F. Hwang, and D. I. Hoult, "Automatic Probe Tuning and Matching,"
Magnetic Resonance in Medicine, vol. 39, pp. 214-222, 1998.
[8] R. D. Venook, B. A. Hargreaves, G. E. Gold, S. M. Conolly, and G. C.
Scott, "Automatic Tuning of Flexible Interventional RF Receiver Coils,"
Magnetic Resonance in Medicine, vol. 54, pp. 983-993, 2005.
[9] E. A. Barberi, J. S. Gati, B. K. Rutt, and R. S. Menon, "A Transmit-
Only/Receive-Only (TORO) RF System for High-Field MRI/MRS
Applications," Magnetic Resonance in Medicine, vol. 43, pp. 284-289,
2000.
[10] A. C. Yung, A. Y. Oner, J. M. Serfaty, M. Feneley, X. Yang, and E.
Atalar, "Phased-Array MRI of Canine Prostate Using Endorectal and
Endourethral Coils," Magnetic Resonance in Medicine, vol. 49, pp. 710-
715, 2003.
[11] G. R. Duensing, H. R. Broker, and J. R. Fitzsimmons, "Maximizing
Signal-to-Noise Ratio in the Presence of Coil Coupling," Journal of
Magnetic Resonance Series B, vol. 111, pp. 230-235, 1996.
[12] P. B. Roemer, W. A. Edelstein, C. E. Hayes, S. P. Souza, and O. M.
Mueller, "The NMR Phased Array," Magnetic Resonance in Medicine,
vol. 16, pp. 192-225, 1990.
[13] X. Zhang, and A. Webb, "Design of a Four-Coil Surface Array for in
Vivo Magnetic Resonance Microscopy at 600 MHz," Concepts in
Magnetic Resonance Part B, vol. 24B(1), pp. 6-14, 2005.