86Magnetic resonance cholangiopancreatography (MRCP) is accepted as the noninva-sive standard for assessment of biliary pathologies. With MRCP, biliary obstruction,cholelithiasis, and malignant strictures can be diagnosed with high confidence.However, for biliary disease with only subtle changes of the biliary duct caliber, in someinstances the spatial resolution achievable at 1.5 T has not been sufficient. One such dis-ease entity is primary sclerosing cholangitis (PSC). In the initial phase of the disease,often only subtle changes in the second- and third-order biliary branches can be seen,with dilatations and small stenoses (“string of beads”). For these patients, the improve-ment in spatial resolution that can be gained at 3 T is expected to be beneficial. Thishypothesis has been confirmed in our preliminary experience.

Figure 86–1 presents images from a T2-weighted 3D FSE scan acquired at 3 T withan isotropic 0.9 mm3 voxel size. Time of acquisition for such a data set is usuallybetween 3 and 5 min with respiratory triggering (using a respiratory belt or navigatortechniques such as prospective acquisition correction [PACE]) when parallel imagingwith an acceleration factor of R � 2 is used. (A) and (B) are consecutive thin MIPs,which show two involved biliary ducts (arrows, draining segment 5/6). Figures 86–1C

Liver: MRCP (Part 1)Christoph J. Zech

Figure 86–1

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and 86–1D present volume rendering of the acquired data set with a view from ante-rior (C) and posterior (D). Such postprocessing gives a fast and realistic overview of theanatomy together with localization of pathology and can be helpful for demonstrationof findings to referring and consulting physicians (e.g., the endoscopist). Figures86–2A and 86–2B show the biliary system of a healthy volunteer with the same high-resolution T2-weighted 3D FSE sequence. In this example, no biliary congestion ispresent. Note the excellent depiction of the cystic duct (arrow) in Fig. 86–2A (a thinMIP). Figure 86–2B (a thick MIP) again provides an overview of the entire biliarysystem, showing absence of pathologic findings.

Figures 86–3A and 86–3B show the comparison of a RARE (rapid acquisition withrelaxation enhancement) sequence, used for thick-slab MRCP, acquired at 1.5 T (A)and 3 T (B) in 47-year-old female patient. The slab thickness was 50 mm for bothscans, with an acceleration factor of R � 3 used in each case. The in-plane resolutionwas 384 � 320 at 1.5 T and 448 � 448 at 3 T with an identical FOV (350 � 350 mm2).TR and TE were 4500 and 754 msec, respectively. The exam is normal, without patho-logic findings. Note the artifact involving the common bile duct (signal extinction)due to flow within the hepatic artery (arrow), visible at both field strengths. Thesuperior SNR and spatial resolution at 3 T result in better contrast of the biliary sys-tem relative to the background, with increased visualization of both the peripheralbiliary tree as well as the pancreatic duct (small arrows). The time interval betweenthe two exams was 24 hours, with the patient not fasting prior to the exam at 3 T.

Figure 86–2

Figure 86–3

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