| 1. To investigate feasibility of using SPIO as a gastrointestinal oral contrast agent during MR cholangiopancreatography(MRCP).2. To select better imaging sequences for MRCP with oral SPIO contrast agent.3. To assess the usefulness of MRCP in the evaluation of pancreaticobiliary diseases.Subjects and Methods1. In Vitro experimentSPIO were diluted to different concentration (0.25mmol/L 0.5 mmol/L 0.75 mmol/L, 1.0mmol/L 1.25 rnmol/L, 1.5 mmol/L 2.0 mmol/L 2.5 mmol/L 3.0 mmol/L 3.5 mmol/L),distilled water was selected as blank control. All the diluted series and distilled water were imaged with single-shot fast spin-echo plus sequences and analyzed their signal intensity. The optimal concentration of SPIO were selected as an oral contrast agent in MRCP.2. Clinical Study(1) 50 consecutive patients suffering from or suspected of different pancreaticobiliary diseases were imaged with plain and oral SPIO contrast agent MRCP, two data acquisition techniques were employed: multislice acquisition postprocessed by maximum intensity projection HASTE-MRCP and single slab Turbo spin-echo pulse(single slab TSE). The depiction of thegallbladder, cystic duct, common bile duct, and pancreatic duct were compared on single slab TSE images and then their statistical differences were evaluated. 17 patients were also imaged with oral Gd-DTPA contrast agent MRCP, the extent of fluid signal suppressed in stomach and duodenum was compared with the oral SPIO MRCP on single slab TSE data acquisition.(2) The depiction of the gallbladder, cystic duct, common bile duct, and pancreatic duct were compared between HASTE-MRCP and single slab TSE on MRCP images under the condition of oral SPIO contrast agent. Statistical differences were evaluated.(3) The MRCP features of pancreaticobiliary diseases were analyzed. Results1. Vitro Experiment:Decreases of the signal intensity on heavy Tz-weighted images were noticed from concentration of 0.25mmolFe/L to 3.5mmolFe/L, when the concentration of SPIO exceed 1.5mmolFe/L, the signal intensity of tube was null .While the signal of distilled water was hyperintense.2. Clinical Study(1) Without oral contrast agent, the hyperintense signal in gastroduodenal often disturbed the depiction of pancreaticobiliary duct. After oral administration of SPIO contrast agent, the high signal intensity from the gastrointestinal fluid was completely suppressed, the depictions of the common bile duct, cystic duct and pancreatic duct were markedly improved comparing with that without oral contrast agent. There was a significant difference between oral SPIO contrast and without oral contrast agent.(2) The fluid signal of stomach and duodenum on oral SPIO MRCP was suppressed more entirely than on oral Gd-DTPA MRCP, there was a significant difference between them.(3) The demonstration of distal common bile duct, pancreatic head duct, pancreatic body duct and pancreatic tail duct significantly higher with single-slab TSE-MRCP acquisition than multislice HASTE-MRCP. There were significant difference between them, but there were no significant indemonstrating gallbladder, cystic duct, upper common bile duct after SPIO contrast improvement. In single-slab images, the loss of signal intensity from the grastrointestinal fluid was more valuable than multislice. Conclusions:1. Oral SPIO as negative gastrointestinal contrast agent may be valuable in improving MRCP. Its effect of suppressing water signals in stomach and duodenum is better than oral Gd-DTPA.2. With oral SPIO contrast agent, the single slab TSE images have more advantage than multislice images on depictions of distal common bile duct and pancreatic duct and on the effect of suppressing water signals of gastroduodenal.3. MRCP has high specificity in diagnosis of choledocholithiasis and is helpful to differentiate between chronic pancreatitis and pancreatic tumors, between benign stricture and malignant stricture. Combined with conventional and contrast-en... |
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