Morphological Analysis and Differentiation of Benign Cystic Neoplasms of the Pancreas Using Computed Tomography and Magnetic Resonance Imaging

Abstract

Purpose: To evaluate morphologic characteristics and establish a standardized diagnostic algorithm to differentiate benign cystic pancreatic tumors (CPTs) in non-pancreatitis patients using multidetector computed tomography (CT) and magnetic resonance imaging (MRI).

Materials and Methods: Patients with histopathologically proven CPTs who had undergone MRI and/or CT and subsequent tumor resection in our institution were retrospectively identified. Images were analyzed for morphology and enhancement patterns by three independent blinded observers. Preoperative image findings were correlated with histopathological results. Based on the evaluated morphologic parameters, a standardized diagnostic algorithm was designed to help characterize the lesions.

Results: A total of 62 consecutive patients with 64 CPTs were identified from the surgical database (21 intraductal papillary mucinous neoplasms; 10 mucinous cystic neoplasms; 12 serous microcystic adenomas; 3 serous oligocystic adenomas; 6 solid pseudopapillary tumors; 12 neuroendocrine neoplasms). The overall averaged accuracy for the 3 observers was 89.9 % for CT and 93.1 % for MRI with increasing overall accuracy in relation to the experience of the observer (88.2 %, 91.5 %, and 93.8 %, respectively). Overall, the generalized kappa value was 0.69 (CT, 0.64; MRI, 0.76); p < 0.001). The accuracy of the standardized diagnostic algorithm was 91.1 %.

Conclusion: It is possible to characterize benign CPTs with MRI and CT, while MRI appears to be superior to CT. Diagnostic accuracy depends on the observer’s experience. The standardized algorithm can aid in the differential diagnosis but still needs to be tested in other patient populations.

Zusammenfassung

Ziel: Beurteilung morphologischer Charakteristika und die Etablierung eines standardisierten diagnostischen Algorithmus für die Differenzierung von benignen, zystischen pankreatischen Tumoren (CPTs) mittels Multidetektor-Computertomografie (CT) und Magnetresonanztomografie (MRT) bei Patienten ohne Pankreatitis.

Material und Methoden: Patienten mit histopathologisch gesicherten CPTs und präoperativer Diagnostik mittels MRT und/oder CT, wurden retrospektiv eingeschlossen. Die Bilder wurden durch 3 unabhängige, verblindete, unterschiedlich erfahrene Untersucher bezüglich Morphologie und Kontrastmittelanreicherungen ausgewertet; als Referenz galt der histopathologische Befund. Anhand der erhobenen bildmorphologischen Charakteristika wurde ein standardisierter diagnostischer Algorithmus zur Läsionscharakterisierung entwickelt.

Ergebnisse: Insgesamt wurden 62 Patienten mit insgesamt 64 CPTs (n = 21 intraduktale papilläre muzinöse Neoplasien, n = 10 muzinös-zystische Neoplasien, n = 12 serös-mikrozystische Adenome, n = 3 serös-oligozystische Adenome, n = 6 solide pseudopapilläre Neoplasien, n = 12 neuroendokrine Neoplasien) aus der chirurgischen Datenbank identifiziert. Die gemittelte Gesamtgenauigkeit für alle drei Befunder lag bei 89,9 % für die CT und 93,1 % für die MRT mit steigender Gesamtgenauigkeit längerer Erfahrung des Befunders (jeweils 88,2, 91,5 und 93,8 %; generalisierte Kappa-Wert = 0,69 (CT = 0,64; MRT = 0,76; p < 0,001). Die Genauigkeit des standardisierten diagnostischen Algorithmus lag bei 91,1 %.

Schlussfolgerung: Die Differenzierung benigner CPTs gelingt gut mittels MRT und CT, wobei die MRT der CT überlegen zu sein scheint. Die diagnostische Treffsicherheit ist erfahrungsabhängig. Der standardisierte Algorithmus könnte als Entscheidungshilfe dienen, sollte jedoch noch an einer weiteren Patientenpopulation getestet werden.

Key words

MRI - CT - cystic pancreatic tumor - IPMN - MCN - SCN

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