Improved Correction of Residual Intensity Nonuniformity in 2D FLAIR MR Images of Brain at 3-T MRI scanner

• Published in: Applied magnetic resonance Vol. 46; no. 8; pp. 941 - 951
• Main Author: Abe, Takayuki
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.08.2015; Springer Nature B.V
• Subjects: Atoms and Molecules in Strong Fields; Brain; Brain diseases; Calibration; Coils; Filtration; Investigations; Laser Matter Interaction; Magnetic fields; Magnetic resonance imaging; Medical imaging; Nonuniformity; Organic Chemistry; Physical Chemistry; Physics; Physics and Astronomy; Scanners; Solid State Physics; Spectroscopy/Spectrometry; Magnetic Resonance Scanner; Local Coil; Intensity Nonuniformity; Receiver Coil; Acute Cerebellitis
• ISSN: 0937-9347; 1613-7507
• DOI: 10.1007/s00723-015-0696-x

The purpose of this study is to correct residual intensity nonuniformities from B 1 inhomogeneities caused by a birdcage body coil. The proposed method modified existing calibration techniques and effectively combined homomorphic filtering. The causes of the nonuniform residual intensity in the brain magnetic resonance resonance (MRI) were investigated by using actual B 1 field mapping with a birdcage body coil and a local receiver coil. The two B 1 field maps were compared. To estimate a residual intensity nonuniformity distribution map, images with a birdcage body coil and images with a local coil were used. Then, a homomorphic filtering technique was effectively applied to only the image produced using a birdcage body coil. The correction map was calculated from the estimated residual intensity nonuniformity distribution map. The image after correction was evaluated. The B 1 + maps were almost the same for different local coils in the same subjects. The B 1 + maps were the same when a birdcage body coil was used as a receiver coil, regardless of whether the local coil was located in the MR scanner or not. However, the B 1 + maps were significantly different between images produced using a birdcage body coil as a receiver coil and those using a local coil as a receiver. The estimated residual nonuniformity map was estimated. The brain MR images obtained by using the proposed method were more uniform than images with conventional corrections. A novel correction method was developed. It has the potential to improve the diagnosis of brain diseases.