A method of magnetic resonance image acquisition and reconstruction is described in which high imaging rates and fast reconstruction times are allowed. The acquisition is a modification of the basic FLASH sequence but with a restricted number N of phase encodings. The encodings are applied sequentially, periodically, and continuously. Images are formed by sliding a window of width N encodings along the acquired data and reconstructing an image for each position of the window. In general the acquisition time per image exceeds the time between successive images, and the method thus has a temporal lag. Experimental studies were performed with a dynamic phantom using 48 phase encodings and a TR of 20 ms, for an image acquisition time of about 1 s. The image display rate in the reconstructed sequence was 12.5 images/s, and the image sequence portrayed the motion of the phantom. Additional studies were done with 24 encodings. It is shown how the sliding window technique lends itself to high-speed reconstruction, with each newly acquired echo used to quickly update the image on display. The combination of the acquisition technique described and a hardware implementation of the reconstruction algorithm can result in realtime MR image acquisition and reconstruction.

T1-weighted spin-echo magnetic resonance (MR) images have had limited soft-tissue contrast at 1.5 T. The authors investigated the effects of echo-time (TE) minimization and fat suppression on MR images of the liver and pancreas. Two sets of MR images were obtained with identical repetition times and other parameters. In 10 subjects with seven liver lesions, images with TEs of 20 and 12 msec were compared. In 18 additional subjects with seven liver lesions and five pancreatic carcinomas, images with identical TEs but with and without fat suppression were compared. Contrast-to-noise ratios (CNRs) were greater with a TE of 12 msec than with a TE of 20 msec for liver versus spleen (7.6 vs 4.9, P = .014) and liver versus lesion (6.9 vs 3.9, P = .031). In patients without fatty liver, CNR for six lesions versus liver was greater (9.5 vs 6.0, P = .014) with fat suppression. CNR between glandular pancreas and cancer was most conspicuous with fat suppression, but fat planes were less distinct. Minimization of TE improves T1-weighted images significantly. Fat suppression also improves CNR, but the disadvantages of fat suppression do not allow elimination of conventional T1-weighted images.

Conventional brain and spinal cord magnetic resonance images were performed in 21 patients with human T-cell lymphotropic virus (HTLV)-1 associated myelopathy/tropical spastic paraparesis, to assess the role of conventional magnetic resonance imaging (MRI) in the disease diagnosis. These patients had no other central nervous system conditions or related risk factors at the time of tropical spastic paraparesis diagnosis. Eleven (52.4%) patients showed nonspecific brain abnormalities on T2-weighted images. The majority (77.2%) of brain abnormalities were located in the deep white matter. A transient contrast-enhancing lesion was identified in the brain of only one patient. In the brain of another patient, 9.0% of the T2-hyperintense lesion load was hypointense on the correspondent T1-weighted images. No differences in terms of demographic, biological, or clinical variables were present between patients with abnormal brain images and those with normal brain magnetic resonance images. Spinal cord T2-weighted images were abnormal in three (14.3%) patients. In one of these three patients, a diffuse but transient edema was found along the entire tract of the spinal cord. White matter lesions were present in the central nervous system of 60% of the cases in this study. However, no correlations between magnetic resonance imaging and clinical findings, and no specificity of lesions were observed. Hence, conventional magnetic resonance imaging is a sensitive but not highly specific tool for diagnosis of tropical spastic paraparesis.

Interferon-beta (IFNbeta) reduces the number and load of new contrast-enhancing lesions (CELs) in patients with multiple sclerosis (MS). However, the ability of IFNbeta to reduce lesion sizes and re-enhancements of pre-existing CELs has not been examined extensively. Activity of contrast re-enhancing lesions (Re-CELs) and contrast single-enhancing lesions (S-CELs) were monitored in ten patients with relapsing-remitting (RR) MS. These patients underwent monthly post-contrast magnetic resonance imaging (MRIs) for an 18-month natural history phase and an 18-month therapy phase with subcutaneous IFNbeta-1b, totaling 37 images per patient. The activity was analysed using the first image as a baseline and registering subsequent active monthly images to the baseline. There was a 76.4% reduction in the number of CELs with IFNbeta therapy. The decrease was greater (P = 0.003) for S-CELs (82.3%) than for Re-CELs (57.4%). S-CELs showed no changes in durations of enhancement and maximal lesion sizes with treatment. Exclusively for Re-CELs, IFNbeta-1b significantly decreased maximal lesion sizes, total number of enhancement periods and total months of enhancement. Thus, IFNbeta appears to be effective in reducing the degree of severity of inflammation among Re-CELs, as reflected by their reduced maximal lesion sizes and durations of enhancement.