Diagnostic Accuracy of 256-Detector Row Computed Tomography in Detection and Characterization of Incidental Pancreatic Cystic Lesions

Abstract

Purpose. To assess the diagnostic value of 256-detector row MDCT in the characterization of incidentally detected pancreatic cystic lesions (PCLs). Materials and Methods. We retrospectively reviewed 6389 studies performed on a 256-row detector scanner, wherein ≥1 PCLs were incidentally detected. Images from a total of 192 patients (99 females; age range 31-90 years) were analysed referring to morphologic predictive signs of malignancy, including multifocality, inner septa, wall thickening, and mural enhancing nodules. Results. We evaluated 292 PCLs in 192 patients (solitary in 145 and ≥2 in 47; incidence 2.05%). Size ranged from 3 to 145 mm (mean 15 mm); body was the most common location (87/292; 29.8%). Intralesional septa were detected in 52/292 lesions (17.8%), wall thickening >2 mm in 13 (4.5%), enhancing wall and mural nodules in 15 (5.1%) and 12 (4.1%), respectively. Communication with ductal system was evident in 45 cases. The most common diagnoses, established by histology or imaging analysis, were IPMNs (about 86%), while serous cystic neoplasia (3.7%) and metastases (0.5%) were the less common. Conclusion. MDCT provides detailed features for characterization of PCLs, which are incidentally discovered with increased frequency due to the widespread use of cross-sectional imaging.

Figure 1

Correlation of MDCT imaging findings with further imaging follow-up studies (MRCP or MDCT), EUS-guided FNA data, or surgical specimen; final diagnoses are also reported for each group (patients stratified according to International Consensus Guidelines for the Management of MCN and IPMN of the Pancreas, 11). For overall final diagnoses (i.e., total IPMNs or MCNs) please refer to data reported in Table 3. MDCT: multidetector computed tomography; MRCP: magnetic resonance cholangiopancreatography; EUS: endoscopic ultrasound; FNA: fine-needle aspiration; IPMN: intraductal papillary mucinous neoplasm (BD: branch duct; MN: main duct); SCN: serous cystic neoplasm; MCN: mucinous cystic neoplasm.

Figure 2

Axial MDCT images performed in a 72-year-old woman presenting with hematuria. At baseline MDCT arterious phase scan (a) demonstrates the presence of a primary neoplastic lesion of the right kidney (arrowheads) and a multiloculated hypodense lesion in pancreatic tail (white arrow), suspicious either for cistoadenoma or metastasis. At subsequent MDCT study performed after right nephrectomy and chemotherapy (b), the pancreatic lesion (white arrow) shows partial shrinkage, confirming the diagnosis of metastasis from renal neoplasia.

Figure 3

(a) MDCT study performed in a 65-year-old man referring to evaluation of hepatic disease. MPR curved reconstruction shows the main pancreatic duct (MPD) along its whole length (arrowheads) and several small cystic lesions (white arrows), without inner septa and no detectable connection with ductal system. These findings were considered consistent with multifocal branch type IPMN. (b) Radial images from a subsequent MRCP study confirm the regular caliper of MPD (arrowheads) and the presence of a higher number of multiple small cysts (white arrows) that spread within the whole pancreatic gland; even if a clear communication with MPD was not present, MRCP confirms the diagnosis of multifocal branch type IPMN.

Figure 4

Two examples of pancreatic enhancement and cystic lesions' evidence in abdominal CT angiographic studies. (a) Poor contrast between the pancreatic parenchyma and cyst evident along the anterior edge of the gland (white arrow) and (78-year-old man) arterial phase does not allow proper lesion's evaluation (uncertain wall thickening). (b) Good contrast between pancreatic parenchyma and simple cyst (curved arrow), which demonstrates clear margins (66-year-old man).

Figure 5

Axial MDCT scan acquired in the venous phase in a 58-year-old man referring to oncologic staging: a subtle branch duct (empty arrow) connects a 2 cm pancreatic cystic lesion (white arrow) of the head with the MPD (arrowhead).

Figure 6

MDCT study performed on an 81-year-old woman for oncologic follow-up (no previous studies performed at our Institution). Axial arterial scan shows an unexpected cystic lesion (white arrow) in the body-tail of the pancreas. MDCT clearly demonstrates the presence of a subtle septum (empty arrow) within the cysts. A further concomitant simple cyst (curved arrow) is evident in the pancreatic head.