SOURCE: http://imageradiology.blogspot.com/2012/06/3d-mrcp-pancreas.html
The 3D TSE sequence can produce high-spatial-resolution MRCP images . Thin sections without a slice gap allow better assessment of small stones, side branches of the main pancreatic duct, and intrahepatic bile ducts. Three-dimensional TSE MRCP may be performed as a series of breath-holds or during free breathing. We acquire 1–2 mm, contiguous slices during free breathing and use the navigator-echo technique to reduce motion effects. The main disadvantage of this technique is the relatively long acquisition time. In addition, navigator-based triggering requires uniform and regular breathing cycles for optimal image quality. If the patient has rapid or irregular breathing, the image quality may be impaired. An alternative method of producing 3D MRCP images is to use a TSE sequence with a 90° flip-back pulse. This sequence is called FRFSE (fast recovery fast spin-echo), DRIVE, or RESTORE. The unique feature of this sequence is that after a long echo-train, the residual transverse magnetization is refocused into a final spin-echo and then flipped along the z-axis by a –90° fast recovery pulse . This accelerates relaxation of the longitudinal magnetization, leading to a reduction in TR without a loss of SNR. It is possible to perform breath-hold 3D MRCP with this sequence. However, the number of slices that may be obtained is substantially less than with respiratory-triggered versions of 3D MRCP.
Three-dimensional volumetric MRCP images are of superior quality and give better delineation of pancreaticobiliary anatomy than conventional 2D images and have the added advantage of multiplanar and postprocessing capabilities.
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