Retrospective Study
Copyright ©The Author(s) 2023. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastrointest Oncol. Jun 15, 2023; 15(6): 1051-1061
Published online Jun 15, 2023. doi: 10.4251/wjgo.v15.i6.1051
Diagnostic accuracy of apparent diffusion coefficient to differentiate intrapancreatic accessory spleen from pancreatic neuroendocrine tumors
Shuai Ren, Kai Guo, Yuan Li, Ying-Ying Cao, Zhong-Qiu Wang, Ying Tian
Shuai Ren, Kai Guo, Yuan Li, Ying-Ying Cao, Zhong-Qiu Wang, Ying Tian, Department of Radiology, Jiangsu Province Hospital of Chinese Medicine, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing 210029, Jiangsu Province, China
Author contributions: Ren S, Guo K, and Li Y contributed equally to this work; Ren S, Wang ZQ, and Tian Y designed the research study; Ren S, Guo K, Li Y, and Cao YY performed the research; Ren S, Guo K, and Li Y analyzed the data; Ren S wrote the manuscript; Wang ZQ and Tian Y revised the manuscript; All authors read and approved the final manuscript.
Supported by the National Natural Science foundation of China, No. 82202135, and No. 82171925; Foundation of Excellent Young Doctor of Jiangsu Province Hospital of Chinese Medicine, No. 2023QB0112; Innovative Development Foundation of Department in Jiangsu Hospital of Chinese Medicine, No. Y2021CX19; and Developing Program for High-level Academic Talent in Jiangsu Hospital of TCM, No. y2021rc03.
Institutional review board statement: The study was reviewed and approved by the ethics committee of Affiliated Hospital of Nanjing University of Chinese Medicine (Approval No. 2017NL-137-05).
Informed consent statement: Informed consent statement was waived due to the retrospective nature of the study.
Conflict-of-interest statement: The authors declare that they have no conflicts of interest.
Data sharing statement: Patient imaging data and histopathology reports contain sensitive patient information and cannot be released publicly due to the legal and ethical restrictions imposed by the institutional ethics committee (Affiliated Hospital of Nanjing University of Chinese Medicine). Data is available upon reasonable request from the following e-mail address: zhongqiuwang@njucm.edu.cn.
Open-Access: This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution NonCommercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: https://creativecommons.org/Licenses/by-nc/4.0/
Corresponding author: Zhong-Qiu Wang, MD, PhD, Chief Doctor, Department of Radiology, Jiangsu Province Hospital of Chinese Medicine, Affiliated Hospital of Nanjing University of Chinese Medicine, No. 155 Hanzhong Road, Nanjing 210029, Jiangsu Province, China. zhongqiuwang0815@163.com
Received: December 30, 2022
Peer-review started: December 30, 2022
First decision: January 22, 2023
Revised: February 1, 2023
Accepted: April 19, 2023
Article in press: April 19, 2023
Published online: June 15, 2023
Processing time: 167 Days and 0.2 Hours
Abstract
BACKGROUND

Intrapancreatic accessory spleen (IPAS) shares similar imaging findings with hypervascular pancreatic neuroendocrine tumors (PNETs), which may lead to unnecessary surgery.

AIM

To investigate and compare the diagnostic performance of absolute apparent diffusion coefficient (ADC) and normalized ADC (lesion-to-spleen ADC ratios) in the differential diagnosis of IPAS from PNETs.

METHODS

A retrospective study consisting of 29 patients (16 PNET patients vs 13 IPAS patients) who underwent preoperative contrast-enhanced magnetic resonance imaging together with diffusion-weighted imaging/ADC maps between January 2017 and July 2020 was performed. Two independent reviewers measured ADC on all lesions and spleens, and normalized ADC was calculated for further analysis. The receiver operating characteristics analysis was carried out for evaluating the diagnostic performance of both absolute ADC and normalized ADC values in the differential diagnosis between IPAS and PNETs by clarifying sensitivity, specificity, and accuracy. Inter-reader reliability for the two methods was evaluated.

RESULTS

IPAS had a significantly lower absolute ADC (0.931 ± 0.773 × 10-3 mm2/s vs 1.254 ± 0.219 × 10-3 mm2/s) and normalized ADC value (1.154 ± 0.167 vs 1.591 ± 0.364) compared to PNET. A cutoff value of 1.046 × 10-3 mm2/s for absolute ADC was associated with 81.25% sensitivity, 100% specificity, and 89.66% accuracy with an area under the curve of 0.94 (95% confidence interval: 0.8536-1.000) for the differential diagnosis of IPAS from PNET. Similarly, a cutoff value of 1.342 for normalized ADC was associated with 81.25% sensitivity, 92.31% specificity, and 86.21% accuracy with an area under the curve of 0.91 (95% confidence interval: 0.8080-1.000) for the differential diagnosis of IPAS from PNET. Both methods showed excellent inter-reader reliability with intraclass correlation coefficients for absolute ADC and ADC ratio being 0.968 and 0.976, respectively.

CONCLUSION

Both absolute ADC and normalized ADC values can facilitate the differentiation between IPAS and PNET.

Keywords: Pancreas; Neuroendocrine tumors; Accessory spleen; Diffusion-weighted imaging; Diagnostic performance

Core Tip: Intrapancreatic accessory spleen (IPAS) presents as a solitary, well-defined, hypervascular mass on contrast-enhanced computed tomography or contrast-enhanced magnetic resonance imaging. They are often misdiagnosed as small (< 3 cm) hypervascular pancreatic neuroendocrine tumors (PNETs). IPAS is innocuous in nature and does not require treatment. However, surgery and/or chemotherapy are recommended for PNETs. The overlap of imaging characteristics between IPAS and PNETs often requires surgical management. Therefore, preoperative characterization is of utmost importance. Our study demonstrated that both absolute apparent diffusion coefficient (ADC) and normalized ADC values (lesion-to-spleen ADC ratios) allow clinically relevant differentiation of IPAS from PNET.