Imaging the postoperative patient: long-term complications of gastrointestinal surgery.

OBJECTIVES: The objectives of this review are (1) to become acquainted with the long-term complications of surgery of the gastrointestinal tract, and (2) to appreciate the appropriate use of imaging in the assessment of long-term complications. BACKGROUND: Gastrointestinal tract surgery comprises a group of procedures performed for a variety of both benign and malignant diseases. In the late postoperative setting, adhesions and internal hernias are the most important complications. and they can be further complicated by volvulus and ischemia. At present, computed tomography (CT) is the workhorse for evaluating late postoperative complications. Accurate imaging assessment of patients is essential for adequate treatment planning. IMAGING FINDINGS OR PROCEDURE DETAILS: In this pictorial essay we will review the most frequent long-term complications after gastrointestinal surgery, including adhesions, afferent loop syndrome, closed-loop obstruction, strangulated obstruction, internal hernias, external hernias, anastomotic strictures and disease recurrence. Examples will be depicted using iconography from the authors' imaging department. CONCLUSIONS: Knowledge of the most frequent complications after gastrointestinal surgery in the late postoperative period is of paramount importance for every radiologist, so that potentially life-threatening situations can be promptly diagnosed and adequate therapy can be planned. TEACHING POINTS: • Long-term postoperative complications of gastrointestinal tract surgery can be divided into procedure-related and disease-related categories. • The most common procedure-related complications are internal hernias and adhesions. • The most frequent disease-related complications are mainly associated with neoplastic or inflammatory recurrence. • Computed tomography is the most useful examination when such complications are suspected.

[Gd-EOB-DTPA-enhanced magnetic resonance imaging: differentiation between focal nodular hyperplasia and hepatocellular adenoma]. / Ressonância magnética hepática com Gd-EOB-DTPA: diferenciação entre hiperplasia nodular focal e adenoma hepatocelular.

UNLABELLED: Gadoxetic acid (Gd-EOB-DTPA) is a contrast media used in magnetic resonance imaging (MRI) for the detection and characterization of hepatic lesions. It shows combined properties of extracellular and biliary excretion, with 50% of the administered dose eliminated by the hepatobiliary pathway. One of its applications, therefore, is the characterization of focal hepatic lesions, including those of hepatocellular nature, such as focal nodular hyperplasia and hepatocellular adenoma. Patients with focal nodular hyperplasia (FNH) are usually asymptomatic and rarely reveal complications. In other hand, hepatocellular adenoma may suffer complications, such as intraperitoneal or intratumoral (sometimes massive) bleeding and the possible progression to malignancy. OBJECTIVES: To determine the value of MRI with Gd-EOB-DTPA in characterizing hepatic lesions, particularly in the differentiation between HNF and AHC. MATERIAL AND METHODS: A retrospective study was carried out by investigating cases of FNH and HCA referred for MR evaluation with Gd-EOB-DTPA in the Department of Radiology of the University Hospitals of Coimbra (HUC) between August 2009 and December 2010. We evaluated 32 patients, 24 with FNH and 8 AHC. The diagnosis was established by histology, follow-up or agreement between imaging methods. In order to evaluate the enhancement after contrast administration in the hepatobiliary phase, we calculated the values of Signal-to-noise ratio (SNR), Contrast-to-noise ratio (CNS) and percentage of enhancement. Statistical analysis was performed with SPSS, version 18, and the tests were evaluated at a significance level of 5%. RESULTS: The SNR and CNR after contrast is significantly different for the two types of lesion (p <0.001 and p = 0.03, respectively), with higher values for both parameters in the group of focal nodular hyperplasia. As for the % of enhancement, there is a statistically significant difference between groups (p = 0.006), again with the FNH group presenting higher values. There are significant differences in both groups among the studies pre-and post-contrast for the CNR (FNH: p <0.001; adenoma: p = 0.017), but for the SNR of the lesion the difference manifests in the HNF group (p <0,001); the CNR values increase in FNH and decrease in hepatocellular adenoma, while for the SNR of the lesion post-contrast values are higher than pre-contrast, in both groups. CONCLUSIONS: Magnetic resonance imaging with hepatospecific contrast is a valuable method for characterization of benign hepatic lesions, helping to differentiate FNH from HCA, based on the different patterns of uptake and retention of Gd-EOB-DTPA.