title: A flexible 32-channel receive array combined with a homogeneous transmit coil for human lung imaging with hyperpolarized 3He at 1.5 T.
abstract: Parallel imaging presents a promising approach for MRI of hyperpolarized nuclei, as the penalty in signal-to-noise ratio typically encountered with (1)H MRI due to a reduction in acquisition time can be offset by an increase in flip angle. The signal-to-noise ratio of hyperpolarized MRI generally exhibits a strong dependence on flip angle, which makes a homogeneous B(1)(+) transmit field desirable. This paper presents a flexible 32-channel receive array for (3) He human lung imaging at 1.5T designed for insertion into an asymmetric birdcage transmit coil. While the 32-channel array allows parallel imaging at high acceleration factors, the birdcage transmit coil provides a homogeneous B(1)(+) field. Decoupling between array elements is achieved by using a concentric shielding approach together with preamplifier decoupling. Coupling between transmit coil and array elements is low by virtue of a low geometric coupling coefficient, which is reduced further by the concentric shields in the array. The combination of the 32-channel array and birdcage transmit coil provides (3)He ventilation images of excellent quality with similar signal-to-noise ratio at acceleration factors R = 2 and R = 4, while maintaining a homogeneous B(1)(+).
authors.affiliation: Academic Unit of Radiology, University of Sheffield, Sheffield, United Kingdom.
authors.forename: Martin H
authors.initials: MH
authors.lastname: Deppe
authors.forename: Juan
authors.initials: J
authors.lastname: Parra-Robles
authors.forename: Helen
authors.initials: H
authors.lastname: Marshall
authors.forename: Titus
authors.initials: T
authors.lastname: Lanz
authors.forename: Jim M
authors.initials: JM
authors.lastname: Wild
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D003287:Contrast Media / Q000008:administration & dosage; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005260:Female; D006371:Helium / Q000008:administration & dosage; D006801:Humans; D007089:Image Enhancement / Q000295:instrumentation*; D007554:Isotopes / Q000008:administration & dosage; D008168:Lung / Q000033:anatomy & histology*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation*; D008280:Magnetics / Q000295:instrumentation*; D008297:Male; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014159:Transducers
chemical_list: D003287:Contrast Media; D007554:Isotopes; D019275:Radiopharmaceuticals; D006371:Helium