Aiming at motion artifacts and off-resonance artifacts in multi-shot diffusion magnetic resonance imaging (MRI), we proposed a joint correction method in this paper to correct the two kinds of artifacts simultaneously without additional acquisition of navigation data and field map. We utilized the proposed method using multi-shot variable density spiral sequence to acquire MRI data and used auto-focusing technique for image deblurring. We also used direct method or iterative method to correct motion induced phase errors in the process of deblurring. In vivo MRI experiments demonstrated that the proposed method could effectively suppress motion artifacts and off-resonance artifacts and achieve images with fine structures. In addition, the scan time was not increased in applying the proposed method.
Objective To investigate the postoperative biochemical changes and the strategy of steroid treatment for autoimmune pancreatitis （AIP）. Methods Six patients with AIP from January 2007 to October 2011 in this hospital were included in this study. Four patients received pancreaticoduodenectomy or distal pancreatectomy for being preoperatively misdiagnosed as malignant tumors. Two patients avoided the unnecessary resection and received the internal drainage for obstructive jaundice and postoperative steroid medication because of a confirmation of AIP by intraoperative frozen biopsy. All the patients underwent routine examinations， including liver function， CA19-9 level， and imaging data. Measurement of serum IgG or IgG4 was performed for fewer patients after operation. Results CA19-9 levels were normal or slightly elevated in six AIP patients. For five patients with AIP in the head of pancreas， preoperative serum γ-GT levels were elevated. For these patients， whether pancreaticoduodenectomy or the internal drainage were performed， TB/DB levels were transiently elevated on day 1 or 4 after operation but dropped to below preoperative levelsor normal levels on day 7 after operation， and serum γ-GT levels among them presented a downward. Serum γ-globulin levels exhibited a downward trend among four AIP patients after resection， while a upward trend was found in another two AIP patients receiving internal drainage. From the limited data， elevated serum level of IgG in the AIP patients were found. As to IgG4， the only case was tested on month 7 after operation， the serum IgG4 level was elevated. CT showed that the swollen status of pancreas obviously reduced on month 3 after operation as compared with before operation.Conclusions Postoperative steroid therapy of AIP should be based on the serum γ-globulin level and operation method. CT or MRI imaging is used to evaluate the response to steroid treatment for the AIP patients.