PURPOSE: A new compressed sensing technique by iterative truncation of small transformed coefficients (ITSC) is proposed for fast cardiac CINE MRI. MATERIALS AND METHODS: The proposed reconstruction is composed of two processes: truncation of the small transformed coefficients in the r-f domain, and restoration of the measured data in the k-t domain. The two processes are sequentially applied iteratively until the reconstructed images converge, with the assumption that the cardiac CINE images are inherently sparse in the r-f domain. A novel sampling strategy to reduce the normalized mean square error of the reconstructed images is proposed. RESULTS: The technique shows the least normalized mean square error among the four methods under comparison (zero filling, view sharing, k-t FOCUSS, and ITSC). Application of ITSC for multi-slice cardiac CINE imaging was tested with the number of slices of 2 to 8 in a single breath-hold, to demonstrate the clinical usefulness of the technique. CONCLUSIONS: Reconstructed images with the compression factors of 3-4 appear very close to the images without compression. Furthermore the proposed algorithm is computationally efficient and is stable without using matrix inversion during the reconstruction.
Magnetic Resonance Imaging, Cine*

No abstract available.
Magnetic Resonance Imaging* ; Relaxation*

No abstract available.
Breast* ; Magnetic Resonance Imaging*

In order to observe the pattern of a flow image on multisection MR imaging technique, a flow phantom experiment was preformed using a superconducting high filed 2.0 Tesla MRI scanner. The pattren of the first section images was homogeneous round at all flow velocities until the turbulence forming level. The patterns of the second section images,however,changed into a homogeneous round shape, a ring shape, a target shape, and a small round shape as the velocity increased. When scanned at velocities higher than the trubulence forming level, the images become distored and irregular, and eventually disappeared after the cut-off velocity. The homogeneous round image senn at the lower velocity levels in throught to be due to the overwhelming effects of fully managetized spins influxed into the imaging section during the prior repetition time(TR). Later in the higer velocity levels the effects of the partially saturated spins and fully magnetized spins influxed during the section transit time(TR/slice number) are added, and result in ring, target, and small round patterns in the second section image.
Magnetic Resonance Imaging*

No abstract available.
Magnetic Resonance Imaging* ; Myelography*

Magnetic resonance imaging with its superior soft tissue contrast resolution and absence of beam hardening artifacts, combined with its ability to perform multiplanar imaging, is now effective tool in diagnostic imagings. Magnetic resonance is primarily a phenomenon that involves atomic nuclei. It provides totally new clinical informations with no known hazards through the use of very weak interactions with endogenous stable magnetic atomic nuclei. This article briefly summarized the basic mechanism of generation and detection of the signals and general sorts of tissue properties which can influence the signals and thereby give rise to tissue contrast. It also describes how the machine-operating parameters can be used to manipulate the tissue contrast observed in the image.
Artifacts ; Magnetic Resonance Imaging*

No abstract available.
Magnetic Resonance Imaging*

OBJECTIVE: Achieving successful posterolateral fusion across the lumbosacral junction is particularly problematic. In our hospital, bilateral S2 laminar hooks coupled with bilateral S1 screws have been appeared to provide successful posterolateral fusion of lumbosacral junction in high non-fusion risk patients. Therefore we study about the safety of sacral lamina hooks insertion. METHODS: We measured the anterior-posterior(A-P) diameter of sacral canal at a point where median sacral crest of S1 and S2 meet on lumbar magnetic resonance(MR) sagittal images. The number of analyzed subjects was one hundred and minimum A-P diameter of sacral canal to insert laminar hooks safely was thought to be 9mm. RESULTS: In 78% of study cases, the sacral canal diameter was 9mm or more. There were no statistically significant difference of sacral canal diameter with age, sex, weight and height. CONCLUSION: Preoperative analysis of the sagittal MR image may be helpful for the safe insertion of the sacral laminar hooks to enhance posterolateral fusion of lumbosacral junction in high non-fusion risk patients. And, safe sacral laminar hooks insertion may be possible in about 78% of study cases.
Humans ; Magnetic Resonance Imaging*

No abstract available.
Humans ; Magnetic Resonance Imaging*

Functional magnetic resonance imaging is a promising imaging technique developed recently to obtain functional maps of the brain, and can be successfully performed on widely available diagnostic MR imaging systems. Thus, the technical principle and application of this new imaging are no more minor part of knowledge in radiology. We describe herein the overview of functional magnetic resonance imaging about the physiologic mechanism, imaging technique, image-processing method and practical application.
Brain* ; Magnetic Resonance Imaging*