MRI screening in hereditary pancreatic cancer: value of various sequences in the detection of early pancreatic cancer

Abstract

Background: In CDKN2A/p16-Leiden mutation carriers with a 15-20% lifetime risk of developing pancreatic ductal adenocarcinoma (PDAC), MRI surveillance has been shown to successfully detect PDAC at an early stage, resulting in increased resectability and survival. The purpose of this study is to retrospectively assess the value of different MRI-techniques in detection of PDAC in a screening setting, including a T1- weighted turbo field echo (TFE) with inversion recovery. Methods: Since the start of the screening program in 2000, 218 CDKN2A/p16-Leiden mutation carriers have been enrolled. During an observation period from January 2012 until August 2017, MRI protocols consisted of axial and coronal T2-weighted turbo spin echo (TSE), fat suppressed T1-weighted gradient echo multiphase contrast-enhanced (MCE) magnetic resonance cholangiopancreaticography (MRCP) and T1-TFE sequences performed at 3.0T. Diffusion weighted imaging (DWI) was added in 2015. Three readers independently analysed current and past MRI examinations for the presence of lesions and other imaging findings in subjects with a PDAC detected during the observation period. Contrast ratios (CR) measured on T1-TFE and T1-MCE were compared with a paired t-test. Results: Nine PDAC were detected, of which 8 (89%) were resectable with an average size of 13.4 mm at pathology. Seven of 9 PDAC were seen by all three readers on both T1-TFE and MCE (8 of 9 by at least two readers). Increased enhancement was seen on the delayed phase of T1-MCE in 7 PDAC. Pancreatic duct dilatation was present in 3 subjects. No cystic lesions were associated with the cancers. In 6 of 8 subjects with an incident tumor, a lesion or indirect signs thereof were seen on previous examinations by one or more readers. In two patients a lesion was retrospectively detected only on T1-TFE of the previous examination. The CR of lesions on T1-TFE was 75% greater compared to unenhanced T1-MCE (P=0.0001) and 58% greater compared to the late-arterial phase T1-MCE (P=0.0004). Conclusions: The inversion recovery prepulse of T1-TFE increases contrast between normal and abnormal pancreatic tissue. Knowledge of imaging features and recognition of subtle changes in the pancreas could improve detection of early pancreatic cancer in a high-risk screening population.