Optimized (31)P MRS in the human brain at 7 T with a dedicated RF coil setup.
The design and construction of a dedicated RF coil setup for human brain imaging ((1)H) and spectroscopy ((31)P) at ultra-high magnetic field strength (7 T) is presented. The setup is optimized for signal handling at the resonance frequencies for (1)H (297.2 MHz) and (31)P (120.3 MHz). It consists of an eight-channel (1)H transmit-receive head coil with multi-transmit capabilities, and an insertable, actively detunable (31)P birdcage (transmit-receive and transmit only), which can be combined with a seven-channel receive-only (31)P array. The setup enables anatomical imaging and (31)P studies without removal of the coil or the patient. By separating transmit and receive channels and by optimized addition of array signals with whitened singular value decomposition we can obtain a sevenfold increase in SNR of (31)P signals in the occipital lobe of the human brain compared with the birdcage alone. These signals can be further enhanced by 30 ± 9% using the nuclear Overhauser effect by B1-shimmed low-power irradiation of water protons. Together, these features enable acquisition of (31)P MRSI at high spatial resolutions (3.0 cm(3)  voxel) in the occipital lobe of the human brain in clinically acceptable scan times (~15 min).
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Bart L
BL
van de Bank
Erwin L. Hahn Institute, University Hospital Duisburg-Essen, Essen, Germany.
Stephan
S
Orzada
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Frits
F
Smits
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.
Miriam W
MW
Lagemaat
Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, John Radcliffe Hospital, Oxford, UK.
Christopher T
CT
Rodgers
Erwin L. Hahn Institute, University Hospital Duisburg-Essen, Essen, Germany.|Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Andreas K
AK
Bitz
Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands.|Erwin L. Hahn Institute, University Hospital Duisburg-Essen, Essen, Germany.
Tom W J
TW
Scheenen
D000328:Adult; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation; D008297:Male; D057054:Molecular Imaging / Q000295:instrumentation; D009778:Occipital Lobe / Q000033:anatomy & histology / Q000378:metabolism*; D010758:Phosphorus / Q000493:pharmacokinetics; D017553:Phosphorus Compounds / Q000378:metabolism*; D066244:Proton Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods*; D011846:Radio Waves; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014018:Tissue Distribution; D014159:Transducers
D017553:Phosphorus Compounds; D010758:Phosphorus
31P-MRS; 31P-MRSI; 7 T; B1 shimming; RF coil; WSVD; array coil; multi-transmit; spectroscopic imaging; ultra-high field