M. S. van Leeuwen

The Atlanta Classification of acute pancreatitis revisited.

In a complex disease such as acute pancreatitis, correct terminology and clear definitions are important. The clinically based Atlanta Classification was formulated in 1992, but in recent years it has been increasingly criticized. No formal evaluation of the use of the Atlanta definitions in the literature has ever been performed.

Level set based cerebral vasculature segmentation and diameter quantification in CT angiography

A level set based method is presented for cerebral vascular tree segmentation from computed tomography angiography (CTA) data. The method starts with bone masking by registering a contrast enhanced scan with a low-dose mask scan in which the bone has been segmented. Then an estimate of the background and vessel intensity distributions is made based on the intensity histogram which is used to steer the level set to capture the vessel boundaries. The relevant parameters of the level set evolution are optimized using a training set. The method is validated by a diameter quantification study which is carried out on phantom data, representing ground truth, and 10 patient data sets. The results are compared to manually obtained measurements by two expert observers. In the phantom study, the method achieves similar accuracy as the observers, but is unbiased whereas the observers are biased, i.e., the results are 0.00+/-0.23 vs. -0.32+/-0.23 mm. Also, the methods reproducibility is slightly better than the inter-and intra-observer variability. In the patient study, the method is in agreement with the observers and also, the methods reproducibility -0.04+/-0.17 mm is similar to the inter-observer variability 0.06+/-0.17 mm. Since the method achieves comparable accuracy and reproducibility as the observers, and since the method achieves better performance than the observers with respect to ground truth, we conclude that the level set based vessel segmentation is a promising method for automated and accurate CTA diameter quantification.

Added value of CT criteria compared to the clinical SAP score in patients with acute pancreatitis

Abstract.Background: To assess the added value of established computed tomography (CT) scores versus the Simplified Acute Physiology (SAP) score in predicting outcome in patients with acute pancreatitis. Methods: Contrast-enhanced CT was performed in 45 patients with acute pancreatitis. The Balthazar score, CT severity index (CTSI), and Schröder score were assessed, and the SAP score was calculated. The predictive values of CT score and SAP score for mortality, need for one or more interventions, and length of hospital stay were compared. The added value of the SAP score to the CT scores was assessed by using ROC (receiver operating curve) analysis. Results: The positive predictive values of the higher Balthazar, CTSI, Schröder, and SAP scores, reflecting severe disease, were 50%, 41%, 41%, and 48%, respectively, for mortality, 85%, 84%, 84%, and 83%, respectively, for need for one or more interventions, and 55%, 66%, 66%, and 65%, respectively, for longer hospital stay. The negative predictive values of the lower Balthazar, CTSI, Schröder and SAP scores were 84%, 92%, 92%, and 42%, respectively, for mortality, 44%, 69%, 69%, and 45%, respectively, for need for one or more interventions, and 44%, 69%, 69%, and 55%, respectively, for longer hospital stay. When CT scores were added to the SAP score, there was no improvement in discriminating power for mortality. Conclusion: To identify patients with severe outcome, there is no clear benefit using established CT scores as opposed to the SAP score. However, the Balthazar score and CTSI are better than the SAP score in predicting a favorable outcome.

Focal nodular hyperplasia: hepatobiliary enhancement patterns on gadoxetic-acid contrast-enhanced MRI

ObjectivesTo assess the range of hepatobiliary enhancement patterns of focal nodular hyperplasia (FNH) after gadoxetic-acid injection, and to correlate these patterns to specific histological features.Materials and methodsFNH lesions, imaged with Gadoxetic-acid-enhanced MRI, with either typical imaging findings on T1, T2 and dynamic-enhanced sequences or histologically proven, were evaluated for hepatobiliary enhancement patterns and categorized as homogeneously hyperintense, inhomogeneously hyperintense, iso-intense, or hypo-intense-with-ring. Available histological specimens of FNHs (surgical resection or histological biopsy), were re-evaluated to correlate histological features with observed enhancement patterns.Results26 FNHs in 20 patients were included; histology was available in six lesions (four resections, two biopsies). The following distribution of enhancement patterns was observed: 10/26 homogeneously hyperintense, 4/26 inhomogeneously hyperintense, 5/26 iso-intense, 6/26 hypointense-with-ring, and 1/26 hypointense, but without enhancing ring. The following histological features associated with gadoxetic-acid uptake were identified: number and type of bile-ducts (pre-existent bile-ducts, proliferation, and metaplasia), extent of fibrosis, the presence of inflammation and extent of vascular proliferation.ConclusionFNH lesions can be categorized into different hepatobiliary enhancement patterns on Gadoxetic-acid-enhanced MRI, which appear to be associated with histological differences in number and type of bile-ducts, and varying the presence of fibrous tissue, inflammation, and vascularization.

Accuracy of Multislice Liver CT and MRI for Preoperative Assessment of Colorectal Liver Metastases after Neoadjuvant Chemotherapy

Introduction: To determine the best imaging modality for preoperative detection, characterization and measurement of colorectal liver metastases (CRLM) after neoadjuvant chemotherapy (NAC). Methods: A total of 79 lesions in 15 patients with CRLM were included. Following NAC, all patients received multislice liver CT (MSCT) and magnetic resonance imaging (MRI) that were scored by two observers for lesion number, type, diameter (mm) and segmental location. Intraoperative findings, histopathology and follow-up imaging were used as reference standard for surgically treated patients; non-surgical candidates underwent follow-up imaging. Results: Lesion detection rate was similar for MSCT and MRI (76 and 80%, respectively, p = 0.648). Lesion characterization was significantly superior (p = 0.021) at MRI (89%, ĸ 0.747, p = 0.001) compared to MSCT (77%, ĸ 0.235, p = 0.005). Interobserver variability for diameter measurement was not significant at MRI (p = 0.909 [95% CI –1.245 to 1.395]), but significant at MSCT (p = 0.028 [95% CI –3.349 to –2.007]). Differences in diameter measurement were independent of observer (p = 0.131), and no statistical effect from imaging modality on diameter measurement was observed (p = 0.095). Conclusion: MRI is superior to MSCT in preoperative characterization and measurement of CRLM after NAC. Lesion detection rates for both modalities are comparable.

CT prediction of irresectability in esophageal carcinoma: value of additional patient positions and relation to patient outcome

Abstract.Background: To improve computed tomographic (CT) prediction of local irresectability and to correlate preoperative CT findings with patient outcome. Methods: Eighty-five patients with esophageal carcinoma underwent CT in supine, left lateral decubitus, and prone positions. CT signs that were indicative of local irresectability included (1) an angle of contact >45° with the aorta; (2) obliteration of triangular fat pad between the tumor, aorta, and spine; (3) tumor contiguous with the aorta in all three positions; and (4) indentation of the airway in all three positions. Results: All CT signs indicative for local irresectability concerning the aorta had comparable percentages of false-positive scans (75%) when correlated with surgical findings. When correlated with pathologic findings, >45° angle of contact with the aorta yielded the fewest false-positive cases (9%). Concerning the airway, additional positions changed the staging correctly in 1 of 18 cases. Median survival was 21 and 8 months, respectively, for tumors considered CT resectable or irresectable. Conclusion: Additional patient positions do not improve the CT prediction of aortic invasion. Predicted resectability correlates with a significant longer life expectancy.

EUS‐guided FNA cytology diagnosis of paraduodenal pancreatitis (groove pancreatitis) with numerous giant cells: conservative management allowed by cytological and radiological correlation

Paraduodenal pancreatitis, or groove pancreatitis, is a rare subtype of chronic pancreatitis that often mimics, clinically and radiologically pancreatic or periampullary cancer. Characteristic imaging features that allow the radiologist to strongly suggest the diagnosis of groove pancreatitis include thickening of the medial duodenal wall and cystic spaces between the duodenum and pancreas. However, most cases do not show typical features, which often make it impossible to differentiate between a benign or malignant disorder. Most patients with groove pancreatitis are middle-aged men with a history of alcohol abuse. Although the exact cause of groove pancreatitis remains unclear, it has been hypothesized that an anatomic variation of the ductal system (e.g. pancreas divisum) renders the paraduodenal area particularly susceptible to the effects of alcoholic injury. In the acute setting, patients usually present with upper abdominal pain, nausea and vomiting. Patients with more chronic disease can present with weight loss and jaundice. If a definitive diagnosis of groove pancreatitis can be made, the therapy of first choice is supportive. If symptoms persist, eventually a resection may be necessary. However, many patients undergo a pancreaticoduodenectomy as primary treatment, because it is often impossible to make a definitive diagnosis of groove pancreatitis and rule out malignancy preoperatively. Endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) cytology is routine in the diagnostic process of patients suspected of pancreatic cancer, and has been proven to be sensitive and specific. However, very little is known about the cytopathological characteristics of groove pancreatitis. This report describes a case of groove pancreatitis with remarkable cytopathology with numerous multinucleated giant cells leading to the differential diagnosis of an acute granulomatous inflammation or a pancreatic undifferentiated carcinoma with osteoclast-like giant cells (UCOCGC). Although the differential diagnosis could not be excluded by cytology alone, conservative non-surgical management and confirmation of the diagnosis were allowed by cytological and radiological correlation and clinical follow-up.

Evaluation of motion correction for clinical dynamic contrast enhanced MRI of the liver

Motion correction of 4D dynamic contrast enhanced MRI (DCE-MRI) series is required for diagnostic evaluation of liver lesions. The registration, however, is a challenging task, owing to rapid changes in image appearance. In this study, two different registration approaches are compared; a conventional pairwise method applying mutual information as metric and a groupwise method applying a principal component analysis based metric, introduced by Huizinga et al (2016). The pairwise method transforms the individual 3D images one by one to a reference image, whereas the groupwise registration method computes the metric on all the images simultaneously, exploiting the temporal information, and transforms all 3D images to a common space. The performance of the two registration methods was evaluated using 70 clinical 4D DCE-MRI series with the focus on the liver. The evaluation was based on the smoothness of the time intensity curves in lesions, lesion volume change after deformation and the smoothness of spatial deformation. Furthermore, the visual quality of subtraction images (pre-contrast image subtracted from the post contrast images) before and after registration was rated by two observers. Both registration methods improved the alignment of the DCE-MRI images in comparison to the non-corrected series. Furthermore, the groupwise method achieved better temporal alignment with smoother spatial deformations than the pairwise method. The quality of the subtraction images was graded satisfactory in 32% of the cases without registration and in 77% and 80% of the cases after pairwise and groupwise registration, respectively. In conclusion, the groupwise registration method outperforms the pairwise registration method and achieves clinically satisfying results. Registration leads to improved subtraction images.