Introduction Early identification of pNETs is a key element to reducing morbidity and mortality in MEN1 patients. Prognosis is associated with tumour size and many pNETs are small subcentimetre lesions and only become symptomatic when the tumour is large. Conventional radiology is suboptimal in detecting such lesions, thus missing the window to remove them at an earlier stage. We compared: (a) linearEUS detection of pNETs in patients with confirmed MEN1 vs triple-phase contrast-enhanced CT/MRI pancreas and (b) incremental benefit of EUS to cross-sectional imaging for detection of small pNETs and quantity of pNETs in this cohort

Methods Between Jan 2008- Oct 2015, a total of 20 patients with clinically confirmed MEN1 underwent baseline assessment with EUS, CT/MRI and biochemical screening. Data were retrospectively retrieved from the hospital electronic records database. Statistical analysis was performed using SPSS v20 on the size and number of pNET detection by EUS and CT/MRI using the Wilcoxon Signed Rank Test and McNemar Chi-square

Results A total of 28 EUS procedures and an equal number of cross sectional imaging (CT/MRI) were performed. pNETs were identified in 95% of all 20 MEN1 cases. Overall median pNET size was 7.1 mm on EUS and 14.5 mm on CT/MRI (p = 0.007). Median value for smallest pNETs detected by EUS was 4.6 mm and 12.7 mm on CT/MRI (p = 0.001). EUS detected more pancreatic lesions/pNETs compared to CT/MRI (p < 0.001) in 25 of the 28 procedures (89.3% more). The remaining 3 procedures showed equal numbers of pNETs detection by both modalities. The interquartile range (IQR) for smallest pNET detected by EUS was 3.0–5.0 mm while IQR for CT/MRI lies between 8.3 mm-14.8mm. EUS detected all 100% cases of pNETs in our series of MEN1 compared to CT/MRI imaging alone which detected 57.9% cases (p = 0.008). 14 of 20 patients had FNA performed with a positive yield of 85.7%. In 50% of patients, pNET measured ≤10 mm. Conclusions In MEN1 patients, CT/MRI underestimated the presence of pNETs in approximately half of all cases compared to EUS and was not able to identify small pNETs (< 8 mm) in all but one case.

Conclusion EUS offers higher sensitivity than cross sectional imaging (CT/MRI) in terms of detecting the number of positive pNET cases as well as a greater number of pancreatic lesions especially subcentimetre ones. EUS should be considered a standard tool in the algorithm for MEN1 workup, instead of an adjunct reserved for diagnostic dilemmas

Disclosure of Interest None Declared