Optimized ROI size on ADC measurements of normal pancreas, pancreatic cancer and mass-forming chronic pancreatitis.

Chao Ma,Li Wang,Panpan Yang,Jianxun Qu,Jing Li,Shi-Yue Chen,Luguang Chen,Mbaiaoure Barak Boukar,Qiang Hao,Li Su,Jian-Ping Lu

doi:10.18632/oncotarget.18457

Abstract

ObjectivesTo investigate the effects of region of interest (ROI) sizes on apparent diffusion coefficient (ADC) measurements for the differentiation of normal pancreas (NP), pancreatic ductal adenocarcinoma (PDAC) and mass-forming chronic pancreatitis (MFCP).ResultsThere were no significant differences for the mean ADCs measured by 12 different-size ROIs for MFCP, or PDAC and NP (P = 0.858–1.0). With the increase of ROI size (≥ 55 mm2), ADCs of PDAC were significantly lower than those of NP (all P < 0.05), but there was no difference of the accuracy in ADC for differentiating the two groups only at a ROI size of 214 mm2. When ROI size was above 99 mm2, ADCs of MFCP were significantly lower than those of NP (all P < 0.05). There were no significant differences for any of the mean ADCs measured by 12 different-size ROIs between PDAC and MFCP (P > 0.05).Materials and MethodsDiffusion-weighted imaging (DWI) was performed on 89 participants: 64 with PDAC, 7 with MFCP, as well as 18 healthy volunteers. ADC maps were created using mono-exponential model. A homemade software was used to measure the mean ADC values of 12 concentric round ROIs (areas: 15, 46, 55, 82, 99, 121, 134, 152, 161, 189, 214, 223, and 245 mm2) for the mass of lesions and the NP tissue.ConclusionsIn ADC measurements, the optimized ROI size is 214 mm2 for the differentiation of PDAC and NP; ROI size of ≥ 99 mm2 is recommended to differentiate between MFCP and NP. ADC was not useful for the differentiation of PDAC and MFCP.

Highlights

Differential diagnosis of mass-forming chronic pancreatitis (MFCP) and pancreatic ductal adenocarcinoma (PDAC) is of clinical significance due to the different treatment strategies [1, 2], and yet this remains challenging in practice because of the similarity of imaging presentations for the two different entities [3,4,5,6]
In apparent diffusion coefficient (ADC) measurements, the optimized region of interest (ROI) size is 214 mm2 for the differentiation of PDAC and normal pancreas (NP); ROI size of ≥ 99 mm2 is recommended to differentiate between MFCP and NP
Comparisons of the mean ADC values were performed and the results demonstrated significant differences among the three participant groups while the ROI size was above 55 mm2

Summary

Introduction

Differential diagnosis of mass-forming chronic pancreatitis (MFCP) and pancreatic ductal adenocarcinoma (PDAC) is of clinical significance due to the different treatment strategies [1, 2], and yet this remains challenging in practice because of the similarity of imaging presentations for the two different entities [3,4,5,6]. Diffusion-weighted imaging (DWI) with quantitative measurement of apparent diffusion coefficient (ADC) values provide an alternative to conventional anatomical magnetic resonance imaging (MRI), such as T1- (T1WI) and T2-weighted imaging (T2WI), for the detection and characterization of cystic and solid pancreatic tumors in clinical practice [7]. Some studies have been carried out to investigate the possibility to differentiate MFCP from PDAC by using qualitative DWI and quantitative ADC [7,8,9,10,11,12]. The effect of ROI size on ADC measurements in normal pancreatic tissue or pancreatic lesions have rarely been studied. The aim of this study was to investigate the influences of ROI size in ADC measurements for the differentiation between normal pancreas (NP), PDAC and MFCP

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Conclusion