Accurate imaging diagnosis of small pancreatic carcinoma/high-grade pancreatic intraepithelial neoplasia using combined indirect imaging findings

INTRODUCTION: Early-stage pancreatic cancer (EPC), including high-grade pancreatic intraepithelial neoplasia (HG-PanIN) and pancreatic cancer ≤ 10 mm, has a favorable prognosis. Indirect imaging findings, such as main pancreatic duct (MPD) irregularities, branch pancreatic duct (BPD) dilation, and focal pancreatic parenchymal atrophy (FPPA), may aid in diagnosis. This study aimed to evaluate their diagnostic performance and assess intermodality agreement. METHODS: Patients with an irregular MPD caliber were included. Indirect imaging findings, including MPD dilation/stenosis, BPD dilation, and FPPA, were evaluated. Positive findings were defined as those detected on computed tomography (CT) or magnetic resonance imaging (MRI). Concordance rates between modalities were also assessed. RESULTS: Among 49 patients (22 malignant [17 with HG-PanIN]), BPD dilation adjacent to an irregular MPD and FPPA were significantly associated with malignancy (P = .013 and .002, respectively) with moderate-to-substantial interobserver agreement. MPD stenosis with FPPA and the combination of all three findings showed the highest specificity (85.2%). The combination of BPD dilation and FPPA achieved the highest diagnostic accuracy (77.6%), although the accuracy based on FPPA alone did not significantly differ. Intermodality agreement ranged from moderate to almost perfect. CONCLUSION: FPPA was a significant indirect imaging finding for diagnosing EPC using CT, MRI, and endoscopic retrograde pancreatography, whereas BPD dilation around an irregular MPD caliber was associated with EPC only in univariate analysis. The combination of characteristic indirect imaging findings may improve diagnostic performance, particularly specificity. This imaging-based diagnostic approach may facilitate early detection of EPC.