Differentiation of pancreatic neuroendocrine carcinoma from pancreatic ductal adenocarcinoma using magnetic resonance imaging: The value of contrast-enhanced and diffusion weighted imaging

Abstract

Pancreatic neuroendocrine carcinoma (PNEC) is often misdiagnosed as pancreatic ductal adenocarcinoma (PDAC). This retrospective study differentiated PNEC from PDAC using magnetic resonance imaging (MRI), including contrast-enhanced (CE) and diffusion-weighted imaging (DWI). Clinical data and MRI findings, including the T1/T2 signal, tumor boundary, size, enhancement degree, and apparent diffusion coefficient (ADC), were compared between 37 PDACs and 13 PNECs. Boundaries were more poorly defined in PDAC than PNEC (97.3% vs. 61.5%, p<0.01). Hyper-/isointensity was more common in PNEC than PDAC at the arterial (38.5% vs. 0.0), portal (46.2% vs. 2.7%) and delayed phases (46.2% vs. 5.4%) (all p<0.01). Lymph node metastasis (97.3% vs. 61.5%, p<0.01) and local invasion/distant metastasis (86.5% vs. 46.2%, p<0.01) were more common in PDAC than PNEC. Enhancement degree via CE-MRI was higher in PNEC than PDAC at the arterial and portal phases (p<0.01). PNEC ADC values were lower than those of normal pancreatic parenchyma (p<0.01) and PDAC (p<0.01). Arterial and portal phase signal intensity ratios and ADC values showed the largest areas under the receiver operating characteristic curve and good sensitivities (92.1%–97.2%) and specificities (76.9%–92.3%) for differentiating PNEC from PDAC. Thus the enhancement degree at the arterial and portal phases and the ADC values may be useful for differentiating PNEC from PDAC using MRI.

The differentiation of pancreatic neuroendocrine carcinoma from pancreatic ductal adenocarcinoma: the values of CT imaging features and texture analysis

“…Pancreatic neuroendocrine carcinoma (PNEC) is a rare tumor that accounts for 2–3% of pancreatic neuroendocrine neoplasms (PNENs) [ 1 , 2 ]. Recently, several studies reported that PNEC usually showed hypovascular pattern in contrast-enhanced computed tomography (CT) or magnetic resonance imaging (MRI) [ 3 – 6 ]. In addition, ill-defined borders and lymph node invasion are also common in PNEC.…”

“…Overlaps in imaging findings between PNEC and PDAC have been reported previously [ 7 ]. In a prior study, we found that 57% of PNEC was misdiagnosed as PDAC [ 6 ].…”

“…Previous several studies have shown that CT and MRI are useful for differential diagnosis of hypovascular pancreatic tumors [ 6 , 12 ]. Recently, texture analysis that extracts, analyzes, and interprets quantitative imaging features has been widely used to diagnose, characterize and improve tumor staging and therapy response assessment in cancer field [ 13 ].…”

Pancreatic Neuroendocrine Neoplasm Invading the Entire Main Pancreatic Duct Diagnosed by a Preoperative Endoscopic Biopsy

“…Some previous reports have investigated the correlation between imaging characteristics and the PNET grade. PNENs are generally enhanced in the early phase on contrast-enhanced CT and MRI ( 26 - 29 ), whereas low enhancement is observed in malignant PNENs ( 30 - 33 ). FDG-PET often reveals an FDG accumulation in cases of malignant or highly proliferative PNENs ( 34 , 35 ).…”

Unmet Needs in Functional and Nonfunctional Pancreatic Neuroendocrine Neoplasms

“…At present most guidelines (ENETS, NANETS) recommend that MEN1 patients with small NF-PanNENs (≤2 cm), which are almost invariably asymptomatic, should be treated with a watch and wait policy [5, 12, 44, 47]. This policy evolved from findings that these small NF-PanNENs were not associated with increased mortality, the NF-PanNENs are multiple, that the patient cannot be cured of all NF-PanNEN lesions without a total pancreatectomy, and that most of these when followed show minimal growth [5, 11, 12, 79-81]. In the case of ZES in MEN1 patients a similar problem exists as the gastrinomas are in the duodenum in 80–90% of cases, they are invariably multiple, 50–70% are associated with local lymph node metastases, they are not curable without aggressive selection such as a Whipple resection, and long-term studies show unoperated patients with < 2–3 cm of imageable lesion have an excellent long-term survival, so it is generally recommend that this group also do not undergo routine resection [11-14, 47, 82, 83].…”