The role of imaging in acute pancreatitis

La radiologia medica https://doi.org/10.1007/s11547-021-01359-3 ABDOMINAL RADIOLOGY The role of imaging in acute pancreatitis Maria Gabriella Brizi1 · Federica Perillo1 · Federico Cannone1 · Laura Tuzza1 · Riccardo Manfredi1 Received: 14 October 2020 / Accepted: 19 April 2021 © The Author(s) 2021 Abstract Acute pancreatitis is one of the most commonly encountered etiologies in the emergency setting, with a broad spectrum of findings that varies in severity from mild interstitial pancreas to severe forms with significant local and systemic complications that are associated with a substantial degree of morbidity and mortality. In this article the radiological aspect of the terminology and classification of acute pancreatitis are reviewed. The roles of ultrasound, computed tomography, and magnetic resonance imaging in the diagnosis and evaluation of acute pancreatitis and its complications are discussed. The authors present a practical image-rich guide, applying the revised Atlanta classification system, with the goal of facilitating radiologists to write a correct report, and reinforcing the radiologist’s role as a key member of a multidisciplinary team in treating patients with acute pancreatitis. Computed tomography is the most performed imaging test for acute pancreatitis. Nevertheless, MRI is useful in many specific situations, due to its superiority soft tissue contrast resolution and better assessment of biliary and pancreatic duct, for example in the ductal disconnection. The purpose if this article is to review recent advances in imaging acquisition and analytic techniques in the evaluation of AP. Keywords Acute pancreatitis · Computed tomography (CT) · MRI · Magnetic resonance cholangiopancreatography (MRCP) · Interstitial edematous pancreatitis · Necrotizing Pancreatitis Definition Acute pancreatitis (AP), an inflammatory disorder of the pancreas, refers to the autodigestion of the pancreas, in which pancreatic enzymes injure pancreatic tissue and lead to dysfunction of the gland, as well as remote organs and systems. The epidemiology of diseases often changes with time—for pancreatitis, this aspect is certainly true. The reasons for such changes are many: population growth and migration, change in patterns of alcohol consumption and tobacco smoking, rising rates of obesity and recognition of metabolic causes of pancreatitis, and increasing use and improving quality of imaging modalities [1–3]. Epidemiology Incidence * Federica Perillo Maria Gabriella Brizi Federico Cannone Laura Tuzza Riccardo Manfredi 1 Dipartimento di diagnostica per immagini, Radioterapia, Oncologia ed Ematologia, Fondazione Universitaria “A. Gemelli”, IRCCS - Università Cattolica del Sacro Cuore, Largo Agostino Gemelli, 8, 00168 Rome, Italy The global pooled incidence of AP is 34 cases per 100,000 general population per year [95% confidence interval (CI) 23–49], with no statistically significant difference between men and women [4]. The disease predominantly affects people between 60 and 75 years old [5]. Also, we can identify regions with high incidence (that are, those with incidence more than 34 cases per 100,000 general population per year) are the North America and Western Pacific regions (as defined by the WHO). Recurrent AP developed in 21% (95% Cl 17–26%) of patients after the first episode of AP, and chronic pancreatitis 13 Vol.:(0123456789) La radiologia medica developed in 36% (95% Cl 20–53%) of patients after recurrent acute pancreatitis [1]. Prevalence The notion of prevalence is typically considered in the context of chronic diseases, yet the prevalence of acute conditions can also be of importance [1]. The pancreatologists had not focused their attention on estimating the prevalence of AP, because it was believed that the majority of patients do not develop long-term consequences, while data suggest that even patients with mild AP (around 80%) have at least twofold higher long-term risk of diabetes mellitus than people in the general population [6, 7]. Thus, a knowledge of prevalence might enable quantification of the predicted burden of sequelae attributable to acute pancreatitis in the general population and guide the effective allocation of health care resources [1]. Mortality The pooled mortality from an episode of AP in seven population-based cohort studies evaluated in the systematic review by Xiao et al. [4] was 1.16 (95% CI 0.85–1.58) per 100,000 general population per year. Determinants for increased risk for mortality in AP are well-established and include persistent organ failure and infected pancreatic necrosis [8–10]. There are two peaks of lethality in AP: the first one, connected with early dysfunction of organs, begins after one week from the disease onset; the second peak, connected with infected centre’s of necrosis, onsets from the second week of the disease. Clinical presentation AP is an inflammatory condition of the pancreas that can cause local injury, systemic inflammatory response syndrome, and organ failure; worldwide AP is a common condition associated with substantial suffering, morbidity, and cost to the health care system [11]. According to the revised Atlanta classification, accurate diagnosis of AP requires at least two of the following three diagnostic features [12]: (1) Abdominal pain consistent with AP. (2) Serum lipase or amylase levels that are at least 3 times the upper limit of the normal range, and (3) Findings of AP on cross-sectional imaging (computed tomography—CT—or magnetic resonance imaging— MRI). 13 If abdominal pain suggests strongly that AP is present, but the serum amylase and/or lipase activity is less than three times the upper limit of normal, as may be the case with delayed presentation, imaging will be required to confirm the diagnosis [13, 14]. If the diagnosis of AP is established by abdominal pain and by increases in the serum pancreatic enzyme activities, a CT is not usually required for diagnosis in the emergency room or on admission to the hospital. The onset of the pancreatitis is considered to coincide with the 1st day of pain, not the day on which the patient presents for care or the day of hospital admission [15]. Phases of AP AP is divided into early and late phases. • The early phase—first week after the onset—is charac- terized by activation of the cytokine cascade with resultant systemic inflammatory response syndrome (SIRS). If SIRS persists there is an increased risk of developing organ failure, that can be—transient—if it resolves within 48 h or—persistent—if it persists for > 48 h [16–18]. • The late phase, starting in the 2nd week and can lasts for weeks to months, occurs only in patients with moderately severe or severe pancreatitis, as defined by persistent organ failure and by local complications [12] and it is characterized by the presence of local complications, systemic manifestations and/or by transient or persistent organ failure. Grading of AP According to the re (...truncated)