In nonfatty breasts, US and MR imaging were more sensitive than mammography for invasive cancer, but both MR imaging and US involved risk of overestimation of tumor extent. Combined mammography, clinical examination, and MR imaging were more sensitive than any other individual test or combination of tests.
A cine series of tagged magnetic resonance (MR) images of the tongue is used to measure tongue motion and its internal deformation during speech. Tagged images are collected in three slice orientations (sagittal, coronal, and axial) during repetitions of the utterance "disouk" (/disuk/). A new technique called harmonic phase MRI (HARP-MRI) is used to process the tagged MR images to measure the internal deformation of the tongue. The measurements include displacement and velocity of tissue points, principal strains, and strain in the line-of-action of specific muscles. These measurements are not restricted to tag intersections, but can be calculated at every pixel in the image. The different motion measurements complement each other in understanding the tongue kinematics and in hypothesizing the internal muscle activity of the tongue.
OAI MR QA results compared favorably to prior publications and identified similar technical issues for geometric measurements. The longitudinal variations measured in the OAI QA process should have minimal impact on the accuracy and reproducibility of cartilage thickness and volume quantification. This stability should enable direct comparison of baseline and follow-up images. Cross-comparison of the results from all four OAI sites reveals that the MR systems are sufficiently uniform to enable results to be combined.
A new technique, tagged Cine-Magnetic Resonance Imaging (tMRI), was used to develop a mechanical model that represented local, homogeneous, internal tongue deformation during speech. The goal was to infer muscle activity within the tongue from tissue deformations seen on tMRI. Measurements were made in three sagittal slices (left, middle, right) during production of the syllable /ka/. Each slice was superimposed with a grid of tag lines, and the approximately 40 tag line intersections were tracked at 7 time-phases during the syllable. A local model, similar to a finite element analysis, represented planar stretch and shear between the consonant and vowel at 110 probed locations within the tongue. Principal strains were calculated at these locations and revealed internal compression and extension patterns from which inferences could be drawn about the activities of the Verticalis, Hyoglossus, and Superior Longitudinal muscles, among others.
After the placebo-controlled extension of the pivotal US trial of glatiramer acetate for the treatment of relapsing multiple sclerosis ended, 208 participants entered an open-label, long-term treatment protocol Magnetic resonance imaging (MRI) was added to the planned evaluations of these subjects to determine the consequences of long-term treatment on MRI-defined pathology and evaluate its clinical correlates. Of the 147 subjects that remained on long-term follow-up, adequate images were obtained on 135 for quantitative MRI analysis. The initial imaging sessions were performed between June 1998 and January 1999 at 2,447 +/- 61 days (mean +/- standard deviation) after the subject's original randomization. Clinical data from a preplanned clinical visit were matched to MRI within 3 +/- 51 days. At imaging, 66 patients originally randomized to placebo (oPBO) in the pivotal trial had received glatiramer acetate for 1,476 +/- 63 days, and 69 randomized to active treatment with glatiramer acetate (oGA) were on drug for 2,433 +/- 59 days. The number of documented relapses in the 2 years prior to entering the open-label extension was higher in the group originally randomized to placebo (oPBO=1.86 +/- 1.78, oGA=1.03 +/- 1.28; P=0.002). The annualized relapse rate observed during the open-label study was similar for both groups (oPBO=0.2 7, +/- 0.45 oGA=0.28 +/- 0.40), but the reduction in rate from the placebo-controlled phase was greater for those beginning therapy with GA (oPBO reduced by 0.66 +/- 0.71, oGA reduced by 0.23 +/- 0.58; P=0.0002). One or more gadolinium enhancing lesions were found in 27.4% of all patients (number of distinct enhancements=1.16 +/- 2.52, total enhanced tissue volume=97 +/- 26 microl). The risk of having an enhancement was higher in those with relapses during the open-label extension (odds ratio 4.65, 95% confidence interval (CI) 2.0 to 10.7; P=0.001). The odds for finding an enhancement was 2.5 times higher for those patients originally randomized to placebo (CI 1.1 to 5.4; P=0.02) compared to those always on glatiramer acetate. MRI-metrics indicative of chronic pathology, particularly measures of global cerebral tissue loss (atrophy), were uniformly worse for those originally on placebo. These observations enrich our long-term follow up of the clinical consequences of treatment with glatiramer acetate to include its apparent effects on MRI-defined pathology. They show that the effect of glatiramer acetate on enhancements is definite, but modest, consistent with the drug's described mechanisms of action, and that a delay in initiating treatment results in progression of MRI-measured pathology that can be prevented.
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