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 758 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The authors report their experience in the optimization of the diagnostic accuracy of Magnetic Resonance Cholangiography (MRC) to detect choledochal stones; pre- and post-MIP post-processing images were compared. Thirty patients with dilated biliary ducts (mean age: 55.6 years) were examined with MRC; two of them had stones in the intrahepatic biliary ducts. The gold standard and the inclusion criterion was ERCP. MRC was carried out with a 1.5 T superconductive magnet (Signa) with T2-weighted FAST SE sequences (TR/TE; 10000/256, matrix: 256 x 128, slice thickness: 3 mm, TA: 6 min 28 s). Coronal MR images were blindly studied before and after MIP post-processing; Friedman's test was used for statistical analysis (p < .05). ERCP showed 92 cases of choledocholithiasis, with the stones ranging .2 to 3.4 cm; MRC before MIP post-processing had 97.1% diagnostic accuracy, 97.8% sensitivity and 95.8% specificity. These values are significantly different from those obtained after MIP (91.4%, 86.9% and 95.8% respectively). In our experience, pre- and post-MIP post-processing MRC can be considered a reliable and accurate noninvasive technique to detect choledochal stones.
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PMID:[Choledocholithiasis: semeiotic and diagnostic accuracy of cholangiography with magnetic resonance]. 928 Sep 39

Basic principle of MR cholangiopancreatography (MRCP) is heavily T2-weighted imaging (hydrography) to use bile and pancreatic juice as "natural contrast medium". Firstly developed sequence for MRCP was a CE-FAST sequence, which employed time-reversed FID signal. The current most popular sequences for MRCP are single-shot fast spin-echo sequences, which are divided into three types (2D single slice, 2D mutiple slice and 3D methods). The advantage of 2D single slice method is conveniently obtained projection imaging within a few seconds of examination time. Both 2D multiple slice and 3D methods consists of a MIP image and a series of source images. The MIP image creates global images of pancreatico-biliary system. The source images provide detailed evaluation of various anatomical structures and abnormalities. By using these sequences properly, MRCP can yield valuable informations of pancreatico-biliary diseases non-invasively.
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PMID:[Basic principles and historical consideration of MR cholangiopancreatography]. 984 94

We study texture projection based on a four region subdivision: magnification, minification, and two mixed regions. We propose improved versions of existing techniques by providing exact filtering methods which reduce both aliasing and overblurring, especially in the mixed regions. We further present a novel texture mapping algorithm called FAST (Footprint Area Sampled Texturing), which not only delivers high quality, but also is efficient. By utilizing coherence between neighboring pixels, performing prefiltering, and applying an area sampling scheme, we guarantee a minimum number of samples sufficient for effective antialiasing. Unlike existing methods (e.g., MIP-map, Feline), our method adapts the sampling rate in each chosen MIP-map level separately to avoid undersampling in the lower level l for effective antialiasing and to avoid oversampling in the higher level l + 1 for efficiency. Our method has been shown to deliver superior image quality to Feline and other methods while retaining the same efficiency. We also provide implementation trade offs to apply a variable degree of accuracy versus speed.
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PMID:Footprint area sampled texturing. 1538 48