Pancreatic Cystic Neoplasms by George H. Sakorafas Vassileios Smyrniotis & Michael G. Sarr

Author:George H. Sakorafas, Vassileios Smyrniotis & Michael G. Sarr
Language: eng
Format: epub
Publisher: Springer Milan, Milano

5.2 Cross-Sectional Imaging (US, CT, MRI)

Cross-sectional imaging modalities remain the mainstay in the detection and assessment of cystic pancreatic tumors. Transabdominal ultrasonography (US) can detect pancreatic cystic lesions; however, given its limited spatial resolution and soft-tissue contrast [2], US is often not very helpful in the evaluation of cystic neoplasms of the pancreas. Multidetector computed tomography (CT) and magnetic resonance imaging (MRI) are the most common radiologic methods used for characterization of these lesions. Many authors argue that MRI due to its greater contrast between fluid and soft tissue allows optical depiction of the morphologic features of cystic pancreatic lesions [2, 3]; however, recent studies suggest that both multidetector CT and MRI provide high-quality images of cystic pancreatic lesions with comparable diagnostic accuracy [4, 5]. Although the accuracy of these methods ranges from 40 to 60 % in providing the correct histologic diagnosis of cystic lesions of the pancreas [6], Visser et al. [5] found that multidetector CT and MRI had an accuracy of 76–82 % and 85–91 % respectively in establishing the diagnosis of malignancy in cystic pancreatic masses. The use of advanced MRI techniques, such as diffusion-weighted imaging and ADC measurements, are less helpful currently in distinguishing neoplasmatic from non-neoplasmatic pancreatic cysts than originally hoped [3].

Several important morphologic features of cross-sectional imaging have been shown to be useful in the diagnostic approach to cystic lesions of the pancreas, including the presence of septa (unilocular, oligolocular <6 internal cysts, multilocular ≥6 internal cysts), the size of internal cysts (microcystic <2 cm, macrocystic ≥2 cm), the presence of calcification or mural nodules, and communication of the cystic lesion with the main pancreatic duct [7–9].

Serous cystic neoplasm (SCN) is a benign cystic neoplasm of the pancreas that is more frequently found in older women [2]. The most common pattern (70 % of the cases) of SCN is a lobulated lesion consisting of numerous cysts (more than 6) varying from a few millimeters to 2 cm in diameter (but typically less than 1 cm) [2, 10, 11] (Figs. 5.1 and 5.2). A central fibrous scar that may be calcified is seen up to 30 % of cases and is considered to be characteristic and virtually pathognomonic [9, 10]. Calcification is better depicted on CT (Figs. 5.1 and 5.2). The presence of a large number of very small cysts with innumerable enhancing septa may actually produce what may look like a solid appearance on CT [10–12]. In these cases, clear depiction of numerous discrete small fluid-filled cysts at MRI (due to the high sensitivity of the method in detecting fluid) will usually be diagnostic [10, 12]. Uncommonly, an SCN may have an oligolocular or macrocystic appearance that is difficult to differentiate from other mucinous forms of cystic neoplasms.

Fig. 5.1Serous cystic neoplasm. Axial unenhanced (a) and contrast-enhanced (b) CT images show a lobulated cystic lesion (arrowheads) in the pancreatic head with multiple thin internal septation and central calcification (arrow). Axial T2-weighted (c) and contrast-enhanced T1-weighted (d) images of the same patient confirmed the cystic

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