Proton nuclear magnetic resonance (NMR) images depict the distribution and concentration of mobile protons modified by the relaxation times T1 and T2. Using the steady-state-free-precession (SSFP) technique, serial coronal images were obtained sequentially over time in laboratory animals with experimental ischemic infarction. Image changes were evident as early as 2 hours after carotid artery ligation, and corresponded to areas of ischemic infarction noted pathologically.
True three-dimensional proton nuclear magnetic resonance (NMR) imaging was performed on an 84-year-old man following a recent cerebral embolic infarction. NMR data obtained using different pulse sequences were inter-correlated, stressing the significance of image appearance in terms of the NMR tissue parameters. Planes selected for display from the three-dimensional data set allowed optimal visualization of the pathology.
Proton nuclear magnetic resonance (NMR) images reflecting T1 relaxation time and approximating proton density were acquired and used to generate T1 rate (1/T1) maps. By region-of-interest selection, measurements of T1 relaxation time were made from discrete volumes of the imaging plane. Such techniques were applied to the study of human cranial neoplasia and associated conditions of differential diagnostic importance (e.g., postoperative changes, radiation necrosis). Inversion-recovery NMR images exhibit a high lesion-detection sensitivity.
Nuclear magnetic resonance (NMR) images were obtained in 12 patients with mass lesions in the posterior fossa and the results compared with X-ray computed tomography (CT). Inversion recovery T1-weighted images demonstrated abnormalities in six of six intrinsic lesions and three of six extrinsic lesions. Spin echo T2-weighted images demonstrated abnormalities in two of two intrinsic lesions and four of five extrinsic lesions. Saturation recovery T1-weighted images were normal in two of two intrinsic lesions and two of four extrinsic lesions. Overall, NMR detected 11 of 12 lesions.
NMR images of 8 patients with neoplasms of the legs were obtained. Volumetric and/or planar NMR data were acquired using a saturation recovery (SR) approach, incorporating magnetization refocusing. NMR images revealed tumors in all patients and correlated well with the extent seen on CT. SR images with a short interpulse delay (tau) demonstrated a significant decrease in signal intensity (SI) in histologically normal fat (n = 4) and marrow (n = 1) adjacent to tumors, consistent with a prolonged T1.
Several important components must be combined to create an effective nuclear magnetic resonance (NMR) imaging system. The most imposing component is the magnet itself, which is most often either resistive or superconducting. In addition, the magnetic field gradient, radiofrequency (RF) coil, spectrometer, computer, and display system are critical factors that require special consideration before selecting an NMR system for a particular clinical usage.
Magnetic resonance (MR) images were obtained with a prototype resistive magnet system in 10 patients, all of whom had been shown to have pituitary tumors by enhanced high-resolution computed tomography (CT). Histologic verification was obtained in eight cases. Inversion-recovery (IR) T1-weighted images revealed the tumor in six of nine cases; saturation-recovery (SR) images with less T1 weighting identified seven of nine tumors; Carr-Purcell-Meiboom-Gill (CPMG) spin-echo T2-weighted images revealed two of four tumors.
