Native T1 mapping of autoimmune pancreatitis as a quantitative outcome surrogate
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To investigate the ability of T1 mapping to visualize and quantify the short-term and mid-term response of autoimmune pancreatitis (AIP) to corticosteroid treatment (CST) and to correlate T1 relaxation time of the pancreas with clinical status and serum IgG4 level.
The institutional review board approved this prospective study, and all patients provided written informed consent. Pancreatic MRI including native T1 mapping was performed in 39 AIP patients before and during CST, and 40 patients without pancreatic diseases served as control. T1 relaxation time of the pancreatic head, body, and tail was measured in each patient. Clinical symptoms and serum IgG4 level of the patients were recorded.
The native T1 relaxation time of AIP was significantly elongated compared to normal pancreatic tissue (1124.5 ms ± 95.7 ms vs 784.3 ms ± 41.8 ms, p < 0.001). After short-term CST (4 weeks), T1 relaxation time of AIP already shortened significantly (957.2 ms ± 97.3 ms, p < 0.001). After mid-term CST (12 weeks), the T1 relaxation time further shortened towards normalization (844.2 ms ± 71.6 ms, p < 0.001). In 33 AIP patients with elevated serum IgG4 at baseline, T1 relaxation time demonstrated a significant positive correlation with serum IgG4 level (r = 0.329, p = 0.011). In six AIP patients with normal serum IgG4 level at baseline, T1 relaxation time shortening preceded or was in accordance with symptom relief.
Native T1 mapping can be used to assess parenchymal inflammation of AIP and to quantify response to treatment. It provides a quantitative outcome surrogate for AIP.
• Parenchymal inflammation in autoimmune pancreatitis results in T1 relaxation time elongation, which shortens after effective treatment.
• T1 relaxation time of the pancreas correlates with serum IgG4 level, and in serum IgG4-negative AIP patients, T1 relaxation time shortening predicts clinical improvement.
• T1 mapping provides a quantitative outcome surrogate for AIP.
KeywordsPancreatitis IgG4 Inflammation Treatment Magnetic resonance imaging
Apparent diffusion coefficient
Analysis of variance
Intraclass correlation coefficient
International consensus diagnostic criteria
Receiver operating characteristic
Region of interest
The authors sincerely acknowledge Dr. Zhong Wang, Ms. Jing An, and Ms. Xinzhi Zhao from Siemens Healthcare for their MR technical support.
This study has received funding from the National Public Welfare Basic Scientific Research Project (2017PT32004) and Chinese Academy of Medical Sciences Initiative for Innovative Medicine (2017-I2M-1-001).
Compliance with ethical standards
The scientific guarantor of this publication is Professor Zheng-yu Jin, the department chair of radiology, Peking Union Medical College Hospital.
Conflict of interest
Tian-yi Qian and Marcel Dominik Nickel are employees from Siemens Healthcare Company, who provided technical support with the T1 mapping prototype sequence and were not involved in the data collection and analysis. The other authors of this manuscript declare no relationships with any companies whose products or services may be related to the subject matter of the article.
Statistics and biometry
No complex statistical methods were necessary for this paper.
Written informed consent was obtained from all subjects (patients) in this study.
Institutional review board approval was obtained.
• performed at one institution
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