Magnetic resonance imaging for local complications of acute pancreatitis: a pictorial review

Acute pancreatitis is a common disease characterized by sudden upper abdominal pain and vomiting. Alcoholism and choledocholithiasis are the most common factors for this disease. The choice of treatment for acute pancreatitis might be affected by local complications, such as local hemorrhage in or around the pancreas, and peripancreatic infection or pseudoaneurysm. Diagnostic imaging modalities for acute pancreatitis have a significant role in confirming the diagnosis of the disease, helping detect the extent of pancreatic necrosis, and for diagnosing local complications. Magnetic resonance imaging (MRI) might be indicated in acute pancreatitis for detecting and characterizing local complications of acute pancreatitis that involve necrotic, hemorrhagic, infectious, vascular, and pseudocyst disorders. The general MRI sequences for pancreatitis require the combined use of T1-weighted, T2-weighted sequences, and magnetic resonance cholangiopancreatography. For imaging of pancreatic necrosis, the combination of T1-weighted and T2-weighted findings with dynamic contrast-enhanced imaging gives a comprehensive evaluation of the extent of necrosis and full range of inflammatory extension. For imaging of infectious complications, dynamic contrast-enhanced examinations might help differentiate pancreatic cellulitis or abscesses, from pancreatic fluid collection or simple pseudocysts. For vascular abnormalities, the combination of cross-sectional pancreatic parenchyma imaging with MRA represents a single diagnostic modality for the full evaluation of peripancreatic artery and vein involvement, such as arterial pseudoaneurysms and venous thromboses. The purpose of this pictorial review is to examine the MRI appearances of various local complications of acute pancreatitis and to discuss the practical setup of MRI in local complications of acute pancreatitis.

Magnetic resonance imaging for acute pancreatitis

Acute pancreatitis is characterized by acute chemical injury of the pancreatic parenchyma and peripancreatic tissue. The increased frequency of death in acute pancreatitis is directly correlated with the degree and progress of pancreatic necrosis. Moreover, the occurrence of some local complications in acute pancreatitis, such as pancreatic hemorrhage, peripancreatic abscess or large pseudocyst, and pseudoaneurysm, could influence the choice of treatment for these patients. Magnetic resonance imaging (MRI) can be used to help evaluate the presence and degree of pancreatic necrosis, and is crucial for identifying complications of acute pancreatitis and predicting prognosis. The purpose of this article is to describe MRI techniques for acute pancreatitis, to review the spectrum of pancreatic and peripancreatic patterns, as well as to survey various complications secondary to acute pancreatitis on MRI. The role of MRI in the initial evaluation and staging of acute pancreatitis is emphasized.

Magnetic resonance imaging versus Acute Physiology And Chronic Healthy Evaluation II score in predicting the severity of acute pancreatitis

OBJECTIVE

To study the correlation between established magnetic resonance (MR) imaging criteria of disease severity in acute pancreatitis and the Acute Physiology And Chronic Healthy Evaluation II (APACHE II) score, and to assess the utility of each prognostic indicators in acute pancreatitis.

MATERIALS AND METHODS

In this study there were 94 patients with acute pancreatitis (AP), all had abdominal MR imaging. MR findings were categorized into edematous and necrotizing AP and graded according to the MR severity index (MRSI). The APACHE II score was calculated within 24h of admission, and local complications, death, duration of hospitalization and ICU were recorded. Statistical analysis was performed to determine their correlation.

RESULTS

In patients with pancreatitis, no significant correlation can be found between the APACHE II score and the MRSI score (P=0.196). The MRSI score correlated well with morbidity (P=0.006) but not with mortality (P=0.137). The APACHE II score correlated well with mortality (P=0.002) but not with the morbidity (P=0.112). The MRSI score was superior to the APACHE II score as a predictor of the length of hospitalization (r=0.52 vs. r=0.35). A high MRSI and APACHE II score correlated with the need for being in the intensive care unit (ICU) (P=0.000 and P=0.000, respectively).

CONCLUSION

In patients with pancreatitis, MRSI is superior to APACHE II in assessing local complications from pancreatitis but has a limited role in determining systemic complications in which the APACHE II score excels.

Current concepts for the diagnosis of acute pancreatitis by multiparametric magnetic resonance imaging

Acute pancreatitis is classically characterized by acute chemical inflammation of the pancreatic gland itself, peripancreatic tissues, and even remote organs. The newly revised Atlanta Classification 2012 redefined the patterns of pancreatic necrosis and local complications in acute pancreatitis. The Atlanta Classification's novelty was in emphasizing that extrapancreatic fat necrosis, which leads to walled-off necrosis, is associated with poor prognosis. Conversely, the free fluid liquid was considered to be less related to complications. The Atlanta's classification's main weakness is that it is mainly computed tomography (CT) based, as contrast-enhanced CT is the predominant imaging technique used for evaluating a wide range of pathological processes of acute pancreatitis. However, some local complications are difficult to distinguish accurately on CT. Recent advances, including significantly better soft-tissue contrast, favor multiparametric magnetic resonance imaging (mpMRI) for a more comprehensive assessment of acute pancreatitis pathology, particularly for small necrotic/fat debris within a collection. In addition, the MRI severity index (MRSI), which combines Balthazar's grade points and points of the extent of pancreatic necrosis, has been proven to be crucial for the initial evaluation, staging, and prognosis of acute pancreatitis. Other innovations, such as the recognition of important MRI features in acute pancreatitis and the utilization of newer, more effective terminology for imaging reporting assistance in the differentiation of the common local complications following this disease, have improved the treatment for acute pancreatitis. In this paper, with reference to the 2012 revised Atlanta classification, we review the strengths and limitations of MRI for identifying acute pancreatitis, the MRI findings of a spectrum of pathological entities, and the important local complications secondary to acute pancreatitis.

Early prediction of acute pancreatitis severity based on changes in pancreatic and peripancreatic computed tomography radiomics nomogram

BACKGROUND

Early identification of severe acute pancreatitis (SAP) is key to reducing mortality and improving prognosis. We aimed to establish a radiomics model and nomogram for early prediction of acute pancreatitis (AP) severity based on contrast-enhanced computed tomography (CT) images.

METHODS

We retrospectively analyzed 215 patients with first-episode AP, including 141 in the training cohort (87 men and 54 women, mean age 51.37±16.09 years) and 74 in the test cohort (40 men and 34 women, mean age 55.49±17.83 years). Radiomics features were extracted from portal venous phase images based on pancreatic and peripancreatic regions. The light gradient boosting machine (LightGBM) algorithm was used for feature selection, a logistic regression (LR) model was established and trained by 10-fold cross-validation, and a nomogram was established based on the best features. The model's predictive performance was evaluated according to the area under the curve (AUC) of the receiver operating characteristic (ROC) curve, sensitivity, specificity, and accuracy.

RESULTS

A total of 13 optimal radiomics features were selected by LightGBM for LR model building. The AUC of the radiomics (LR) model was 0.992 [95% confidence interval (CI): 0.963-0.996] in the training cohort, 0.965 (95% CI: 0.924-0.981) in the validation cohort, and 0.894 (95% CI: 0.789-0.966) in the test cohort. The sensitivity was 0.862 (95% CI: 0.674-0.954), the specificity was 0.800 (95% CI: 0.649-0.899), and the accuracy was 0.824 (95% CI: 0.720-0.919). The nomogram based on the 13 radiomics features showed that SAP would be predicted when the total score was greater than 124.

CONCLUSIONS

The radiomics model based on enhanced-CT images of pancreatic and peripancreatic regions performed well in the early prediction of AP severity. The nomogram based on selected radiomics features could provide a reference for AP clinical assessment.

CT and MR imaging patterns for pancreatic carcinoma invading the extrapancreatic neural plexus (Part I): Anatomy, imaging of the extrapancreatic nerve

Pancreatic carcinoma is an extremely high-grade malignant tumor with fast development and high mortality. The incidence of pancreatic carcinoma continues to increase. Peripancreatic invasion and metastasis are the main characteristics and important prognostic factors in pancreatic carcinoma, especially invasion into the nervous system; pancreatic nerve innervation includes the intrapancreatic and extrapancreatic nerves. A strong grasp of pancreatic nerve innervation may contribute to our understanding of pancreatic pain modalities and the metastatic routes for pancreatic carcinomas. Computed tomography (CT) and magnetic resonance imaging (MRI) are helpful techniques for depicting the anatomy of extrapancreatic nerve innervation. The purpose of the present work is to show and describe the anatomy of the extrapancreatic neural plexus and to elucidate its characteristics using CT and MRI, drawing on our own previous work and the research findings of others.

CT and MR imaging patterns for pancreatic carcinoma invading the extrapancreatic neural plexus (Part II): Imaging of pancreatic carcinoma nerve invasion

Computed tomography (CT) and magnetic resonance imaging (MRI) are excellent modalities which have the ability to detect, depict and stage the nerve invasion associated with pancreatic carcinoma. The aim of this article is to review the CT and MR patterns of pancreatic carcinoma invading the extrapancreatic neural plexus and thus provide useful information which could help the choice of treatment methods. Pancreatic carcinoma is a common malignant neoplasm with a high mortality rate. There are many factors influencing the prognosis and treatment options for those patients suffering from pancreatic carcinoma, such as lymphatic metastasis, adjacent organs or tissue invasion, etc. Among these factors, extrapancreatic neural plexus invasion is recognized as an important factor when considering the management of the patients.

MR imaging of hemorrhage associated with acute pancreatitis

PURPOSE

To study MRI findings of hemorrhage in acute pancreatitis (AP) and correlate the presence and extent of hemorrhage with the MR severity index (MRSI), Acute Physiology And Chronic Health Evaluation (APACHE) II scores, and clinical outcome.

MATERIALS AND METHODS

This retrospective study included 539 patients with AP. Hemorrhage was defined as areas of hyperintensity in or outside the pancreas on liver imaging with volume acceleration flexible (LAVA-Flex). The presence of hemorrhage was classified into three areas: within the pancreatic parenchyma, retroperitoneal space, and sub-or intraperitoneal space. Involvement of each area was awarded 1 point resulting in the hemorrhage severity index (HSI) score. The predicted severity of AP was graded by MRSI and APACHE II score. The association between HSI, MRSI, and APACHE II scores was analyzed. The length of hospital stay and organ dysfunction was used as clinical outcome parameters.

RESULTS

Among 539 AP patients, 62 (11.5%) had hemorrhage. The prevalence of hemorrhage was 1.1% (2/186), 13.9% (43/310), and 39.5% (17/43) in predicted mild, moderate, and severe AP, respectively, based on MRSI (χ2 = 55.3, p = 0.00); and 7.7% (21/273) and 19.2% (18/94) in predicted mild and severe AP, respectively, based on APACHE II (χ2 = 21.2, p = 0.00). HSI score significantly correlated with MRSI (r = 0.36, p < 0.001) and APACHE II scores (r = 0.21, p = 0.00). The prevalence of organ dysfunction was higher and length of hospital stay was longer in patients with hemorrhage than in those without hemorrhage (p < 0.01).

CONCLUSIONS

Hemorrhage in AP is common. The presence of hemorrhage, rather than its extent, correlates with poor clinical outcome.

MR imaging for blunt pancreatic injury

OBJECTIVE

To study the MR imaging features of blunt pancreatic injury.

MATERIALS AND METHODS

Nine patients with pancreatic injury related to blunt abdominal trauma confirmed by surgery performed MR imaging. Two abdominal radiologists conducted a review of the MR images to assess pancreatic parenchymal and pancreatic duct injury, and associated complications.

RESULT

Diagnostic quality MR images were obtained in each of the nine patients. In the nine patients, pancreatic fracture, laceration and contusion were depicted on MR imaging in five, one and three patients, respectively. There were six patients with pancreatic duct disruption, eight patients with peripancreatic fluid collections, and four patients with peripancreatic pseudocyst or hematoma, respectively. All of the MR imaging findings was corresponded to surgical findings.

CONCLUSION

MR imaging is an effective method to detect blunt pancreatic injury and may provide information to guide management decisions.

Magnetic resonance imaging of retroperitoneal interfascial plane involvement in acute pancreatitis

BACKGROUND

To study the magnetic resonance imaging (MRI) features of acute pancreatitis (AP) involving the retroperitoneal interfascial planes and to analyze the correlations of interfascial plane involvement with the magnetic resonance severity index (MRSI) and the Acute Physiology and Chronic Health Evaluation (APACHE II) scoring system.

METHODS

A total of 316 consecutive patients with AP between November 2011 and August 2013 were retrospectively analyzed. The extension and path of the inflammation spreading along the retroperitoneal interfascial plane on MRI were graded from grade 0 to grade 5. The relationships between interfascial plane involvement and MRSI and APACHE II were analyzed.

RESULTS

Of the 316 patients with AP, 293 patients (92.7%) had interfascial plane involvement, which appeared as interfascial plane edema, thickening and effusion. There were 60, 105, 78, 25, and 25 patients in grades 1, 2, 3, 4, and 5, respectively. Interfascial plane involvement strongly correlated with the MRSI score (r=0.703), but was only weakly correlated with the APACHE-II score (r=0.291).

CONCLUSIONS

MRI depicts the characteristics of interfascial plane involvement in AP. The value of interfascial plane involvement for determining the disease severity is likely to be limited.

The normal transverse mesocolon and involvement of the mesocolon in acute pancreatitis: an MRI study

OBJECTIVE

To study the MRI findings of the normal transverse mesocolon and the involvement of the mesocolon in acute pancreatitis (AP) as well as the relationship between the involvement of the mesocolon and the severity of AP.

MATERIALS AND METHODS

Forty patients without pancreatic disorders were retrospectively analyzed to observe the normal transverse mesocolon using MRI; 210 patients with AP confirmed by clinical and laboratory tests were retrospectively analyzed using MRI to observe transverse-mesocolon involvement (TMI). The severity of TMI was recorded as zero points (no abnormalities and transverse-mesocolon vessel involvement), one point (linear and patchy signal in the transverse mesocolon) or two points (transverse-mesocolon effusion). The AP severity was graded by the MRI severity index (MRSI) and the Acute Physiology And Chronic Healthy Evaluation II (APACHE II) scoring system. The correlations of TMI with MRSI and APACHE-II were analyzed.

RESULTS

In a normal transverse mesocolon, the display rates of the middle colic artery, the middle colic vein and the gastrocolic trunk on MRI were 95.0%, 82.5% and 100.0%, respectively. Of the 210 patients with AP, 130 patients (61.9%) had TMI. According to the TMI grading, 40%, 39% and 20% of the patients were graded at zero, one and two points, respectively. TMI was strongly correlated with the MRSI score (r = 0.759, P = 0.000) and the APACHE-II score (r = 0.384, P = 0.000).

CONCLUSION

MRI could be used to visualize transverse-mesocolon involvement. The severity of TMI could reflect that of AP in the clinical setting and imaging. TMI might be a supplementary indicator of the severity of AP.

Fatty liver in acute pancreatitis: characteristics in magnetic resonance imaging

OBJECTIVE

The objective of this research was to study the characteristics of fatty liver (FL) in acute pancreatitis (AP) in 2-dimensional in-phase (IP)/out-of-phase (OP) magnetic resonance imaging (MRI).

METHODS

Fifty patients with AP (23 men, 27 women; mean age, 44 [SD, 12] years [range, 16-73 years]) were included in this retrospective study. Patients' informed consent was waived. All of them performed abdominal MRI within 72 hours of symptom onset and MRI follow-up. The severity of the AP was graded according to the magnetic resonance severity index (MRSI). The MRSI cutoff was 7.0 points between the mild and the severe AP. Fatty liver in MRI was determined by the hepatic signal intensity difference between OP and IP images. Correlations between the severity of FL and MRSI or serum triglyceride levels were analyzed.

RESULTS

Of the 50 patients with AP, FL was found in 66% of patients' MRIs. A close correlation can be seen between the difference of liver signal intensities on IP/OP images and the MRSI (r = 0.83, P < 0.001). Close correlations were found between FL appearance on MRI and serum triglyceride levels in both mild (r = 0.93, P < 0.001) and severe AP (r = 0.95, P < 0.001). During follow-up MRI, the appearance of FL decreased following the decrease in MRSI scores and serum triglyceride levels in both mild and severe AP.

CONCLUSIONS

Fatty liver in AP is frequently observed in MRI. The appearance of FL in MRI may decrease after subsidence of AP.

MR imaging of acute pancreatitis: correlation of abdominal wall edema with severity scores

OBJECTIVE

To study MRI findings of abdominal wall edema (AWE) in acute pancreatitis as well as correlations between AWE and the severity of acute pancreatitis according to the MR severity index (MRSI) and the Acute Physiology And Chronic Healthy Evaluation III (APACHE III) scoring system.

MATERIALS AND METHODS

A total of 160 patients with AP admitted to our institution between December 2009 and March 2011 were included in this study. MRI was performed within 48 h after admission. MRI findings of acute pancreatitis were noted, including AWE on the MRI. The abdominal wall area was divided into quarters, and each area involved was recorded as 1 point to score the severity of AWE. The severity of acute pancreatitis was studied using both the MRSI and the APACHE III scoring system. Spearman correlation of AWE with the MRSI and the APACHE III scoring system was analyzed.

RESULTS

In 160 patients with acute pancreatitis, 53.8% had AWE on MRI. The average AWE score was 1.2±1.4 points. The prevalence of AWE was 30.5%, 64.5% and 100% in mild, moderate and severe AP, respectively, according to MRSI. AWE on MRI was correlated with MRSI scores (r=0.441, p=0.000). According to APACHE III scores, the averages were 2.0±1.1 and 2.6±1.1 points in mild AP and severe AP, respectively (P=0.016). AWE was slightly correlated with the APACHE III scores (r=0.222, p=0.005).

CONCLUSION

AWE on MRI in acute pancreatitis is common, which may be a supplementary indicator in determining the severity of AP.

Gastrointestinal tract involvement in acute pancreatitis: initial findings and follow-up by magnetic resonance imaging

BACKGROUND

To study the initial and follow up patterns of gastrointestinal tract involvement in acute pancreatitis (AP) using magnetic resonance imaging (MRI).

METHODS

A total of 209 patients with AP undergoing abdominal MRI on 1.5 T MRI were compared to 100 control patients selected from our daily clinical caseload who underwent MRI over the same recruitment period and had no other disease which can cause abnormality of gastrointestinal tract. Initial and follow up MRI examinations of gastrointestinal tract abnormalities were noted for AP patients. The severity of AP was graded by the MRSI and APACHE II. Spearman correlation of gastrointestinal tract involvement with MRSI and APACHE II was analyzed.

RESULTS

In 209 patients with AP, 63% of the AP patients on their initial MRI exams and 5% of control subjects had at least one gastrointestinal tract abnormality (P<0.05). In the control group, thirty-seven patients were normal on MRI, 24 patients with renal cysts, eighteen patients with liver cysts, eleven patients with liver hemangiomas, and ten patients with splenomegaly. The abnormalities of gastrointestinal tract observed in AP patients included thickened stomach wall (20%), thickened duodenum wall (27%), thickened ascending colon wall (11%), thickened transverse colon wall (15%), and thickened descending colon wall (26%), among others. Gastrointestinal tract abnormalities were correlated with the MRSI score (r=0.46, P<0.05) and APACHE II score (r=0.19, P<0.05). Among 62 patients who had follow up examinations, 26% of patients had gastrointestinal tract abnormality, which was significantly lower than that in the initial exams (P<0.05). Resolution of gastrointestinal tract abnormal MRI findings coincided with symptom alleviation in AP patients.

CONCLUSIONS

Gastrointestinal tract abnormalities on MRI are common in AP and they are positively correlated with the severity of AP. It may add value for determining the severity of AP.

Acute Pancreatitis in Patients With a Medical History of Type 2 Diabetes Mellitus: Clinical Findings and Magnetic Resonance Imaging Characteristics

OBJECTIVE

To determine the characteristics of type 2 diabetes mellitus (T2DM)-related acute pancreatitis (AP) on magnetic resonance imaging (MRI).

METHODS

Retrospectively studied 262 patients with AP were admitted to our institution and underwent MRI. Diagnosis of T2DM-related AP was based on clinical manifestations, laboratory tests, and MRI. Pancreatic/peripancreatic changes were assessed on MRI.

RESULTS

Fifty-three (20.2%) patients with T2DM-related AP and 209 (79.8%) with nondiabetic AP were enrolled. On MRI, a higher prevalence of necrotizing pancreatitis (P < 0.001), pancreatic necrosis >30% (57.5% vs 29.2%; P = 0.006), hemorrhage (35.8% vs 19.1%; P = 0.009), abdominal wall edema (67.9% vs 46.8%; P = 0.006), walled-off necrosis (43.2% vs 14.6%; P < 0.001), and infected collections (P < 0.001) were registered in T2DM with AP. T2DM-related AP sustained greater magnetic resonance severity index (mean, 5.1 [range, 2-10] vs 3.4 [range, 1-10]; P < 0.001), higher incidence of moderate and severe pancreatitis (69.8% vs 40.2%; P < 0.001), higher organ failure (45.3% vs 22%; P = 0.001), and prolonged hospitalization (mean, 25.2 [range, 10-63] vs 16 [range, 5-48] days; P < 0.001).

CONCLUSIONS

Type 2 diabetes mellitus-related AP is more moderate-to-severe pancreatitis, and it correlates with MRI characteristics of the pancreas itself, hemorrhage, abdominal wall, and infected collections.

Magnetic resonance imaging for the normal mesostenium and involvement of the mesostenium in acute pancreatitis

The main point of this paper is to study MRI findings of the normal mesostenium and the involvement of the mesostenium in acute pancreatitis and to discuss the relationship between the involvement of the mesostenium and the severity of acute pancreatitis. In clinical practice, the mesenterical involvement in acute pancreatitis was often observed on MRI in daily works, which was little recorded in the reported studies. We conducted the current study to assess the mesenterical involvement in acute pancreatitis with MRI. We found that the mesenterical involvement of acute pancreatitis patients is common on MRI. The mesenterical involvement has a positive correlation with the MR severity index and the Acute Physiology and Chronic Healthy Evaluation II scoring system. It has been shown that MR can be used to visualize mesenterical involvement, which is a supplementary indicator in evaluating the severity of acute pancreatitis and local and systemic complications.

Differentiating pancreatic neuroendocrine tumors from pancreatic ductal adenocarcinomas by the "Duct-Road Sign": A preliminary magnetic resonance imaging study

To assess the duct-road sign and tumor-to-duct ratio (TDR) in MRI for differentiating pancreatic neuroendocrine tumors (PNETs) from pancreatic ductal-adenocarcinomas (PDACs).Retrospectively reviewed MRI characteristics of 78 pancreatic masses (histopathology-proven 25 PNETs and 53 PDACs). Receiver operating characteristics with TDR and diagnostic performance of the duct-road sign for differential diagnosis were performed.The prevalence of duct-road sign in PNETs was higher than that for PDACs (84% vs 0%; P < .001). A strong correlation (r = 0.884, P < .001) was observed between MRI for PNETs and the frequency of this sign. Performance characteristics of the duct-road sign in MRI for PNET diagnosis were sensitivity (84%, [21 of 25]), specificity (100%, [53 of 53]), positive predictive value (100%, [21 of 21]), negative predictive value (92.9%, [53 of 57]), and accuracy (94.8%, [74 of 78]). In the intention-to-diagnose analysis, the corresponding values were 67.7% (21 of 31), 100% (53 of 53), 100% (21 of 21), 84.1% (53 of 63), and 88.1% (74 of 84). The TDR in PNETs was observed to be greater than that in PDACs (14.6 ± 9.3 vs 6.9 ± 3.8, P = .001). TDR with a cut-off value of 7.7 had high sensitivity (84%) and specificity (66%) with area under curve (0.802, 95% CI: 0.699, 0.904; P < .001) for distinguishing PNETs from PDACs.The presence of duct-road sign and TDR > 7.7 on MRI may assist in diagnosis for PNET instead of PDAC.

A new logistic regression model for early prediction of severity of acute pancreatitis using magnetic resonance imaging and Acute Physiology and Chronic Health Evaluation II scoring systems

BACKGROUND

The aim of this study was to develop a new model constructed by logistic regression for the early prediction of the severity of acute pancreatitis (AP) using magnetic resonance imaging (MRI) and the Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system.

METHODS

This retrospective study included 363 patients with AP. The severity of AP was evaluated by MRI and the APACHE II scoring system, and some subgroups of AP severity were constructed based on a combination of these two scoring systems. The length of stay and occurrence of organ dysfunction were used as clinical outcome indicators and were compared across the different subgroups. We combined the MRI and APACHE II scoring system to construct the regression equations and evaluated the diagnostic efficacy of these models.

RESULTS

In the 363 patients, 144 (39.67%) had systemic inflammatory response syndrome (SIRS), 58 (15.98%) had organ failure, and 17 (4.68%) had severe AP. The AP subgroup with a high MRI score and a simultaneously high APACHE II score was more likely to develop SIRS and had a longer hospitalization. The model, which predicted the severity AP by combining extrapancreatic inflammation on magnetic resonance (EPIM) and APACHE II, was successful, with an area under the receiver operating characteristic (ROC) curve (AUC) of 0.912, which was higher than that of any single parameter. Other models that predicted SIRS complications by combining MRI parameters and APACHE II scores were also successful (all P<0.05), and these models based on EPIM and APACHE II scores were superior to other models in predicting outcome.

CONCLUSIONS

The combination of MRI and clinical scoring systems to assess the severity of AP is feasible, and these models may help to develop personalized treatment and management.

Medical imaging for pancreatic diseases: Prediction of severe acute pancreatitis complicated with acute respiratory distress syndrome

In this editorial we comment on the article published in the recent issue of the World Journal of Gastroenterology [2022; 28 (19): 2123-2136]. We pay attention to how to construct a simpler and more reliable new clinical predictive model to early identify patients at high risk of acute respiratory distress syndrome (ARDS) associated with severe acute pancreatitis (SAP), and to early predict the severity of organ failure from chest computed tomography (CT) findings in SAP patients. As we all know, SAP has a sudden onset, is a rapidly changing condition, and can be complicated with ARDS and even multiple organ dysfunction syndrome, and its mortality rate has remained high. At present, there are many clinical scoring systems for AP, including the bedside index for severity in AP, acute physiology and chronic health evaluation II, systemic inflammatory response syndrome, Japanese severe score, quick sepsis-related organ failure assessment, etc. However, some of these scoring systems are complex and require multiple and difficult clinical parameters for risk stratification. Although the aforementioned biomarkers are readily available, their ability to predict ARDS varies. Accor-dingly, it is extremely necessary to establish a simple and valuable novel model to predict the development of ARDS in AP. In addition, the extra-pancreatic manifestations of AP patients often involve the chest, among which pleural effusion and pulmonary consolidation are the more common complications. Therefore, by measuring the semi-quantitative indexes of chest CT in AP patients, such as the amount of pleural effusion and the number of lobes involved as pulmonary consolidation, it has important reference value for the early diagnosis of SAP complicated with ARDS and is expected to provide a basis for the early treatment of ARDS.

Early-phase vascular involvement is associated with acute pancreatitis severity: a magnetic resonance imaging study

BACKGROUND

Although a number of studies have reported on the vascular abnormalities detected by magnetic resonance imaging (MRI) in patients with late-phase acute pancreatitis (AP), few have studied those occurring in the early phase of the disease. The aim of this research was to investigate the MRI findings of early vascular abnormalities in AP and to analyze the correlation of the prevalence of vascular involvement with the severity of AP based on the MR severity index (MRSI) and Acute Physiology and Chronic Health Evaluation (APACHE) II scores.

METHODS

A retrospective analysis was conducted of 301 consecutive AP patients who were admitted to our institution between March 2013 and June 2019. All patients underwent initial MRI during the early phase of pancreatitis and one or more repeat MRI scans in the late phase. Peripancreatic vascular conditions and pancreatitis were assessed using T1-/T2-weighted imaging and dynamic-enhanced MRI. The association between the prevalence of vascular involvement and AP severity graded according to the MRSI or APACHE II score was analyzed using Spearman's rank correlation.

RESULTS

Among 301 AP patients, 75 (24.9%) had at least one MRI-detected vascular abnormality. Overall, vascular involvement on MRI was higher in necrotizing pancreatitis than in edematous pancreatitis [43.2% (54/125) vs. 11.9% (21/176), χ2=38.2, P<0.001]. In the early phase of AP, the prevalence of splenic vein phlebitis, portal vein phlebitis, and splenic arterial arteritis was 24.9% (75/301), 22.3% (67/301), and 19.9% (60/301), respectively. Splenic vein phlebitis was seen on initial MRI in 55.6% (15/27) of patients who had splenic vein thrombosis on repeat MRI. The MRSI scores showed that the prevalence of splenic vein phlebitis, portal vein phlebitis, and splenic arterial arteritis, respectively, was correlated with the severity of pancreatitis (r=0.532, 0.487, and 0.456; all P<0.01). The APACHE II scores showed that the prevalence of MRI-detected vascular involvement was significantly correlated with AP severity (r=0.335, P<0.05).

CONCLUSIONS

Vascular abnormalities, including splenic vein phlebitis and splenic arterial arteritis, are commonly seen on MRI in patients with early-phase AP, and they may be supplementary indicators that can reflect the severity of pancreatitis.

Diagnostic value of imaging examination in autoimmune pancreatitis

Autoimmune pancreatitis (AIP) is a special type of chronic pancreatitis mediated by autoimmunity factors. It can be divided into two categories according to pathological characteristics: Lymphoplasmacytic sclerosing pancreatitis and idiopathic duct-centric pancreatitis. In the clinical setting, the imaging manifestations of some AIP cases are atypical, so it is difficult to distinguish it from general pancreatitis, pancreatic ductal adenocarcinoma, lymphoma, and other malignant disorders. Most importantly, the treatment for and prognosis of these diseases are different. Therefore, a timely correct imaging diagnosis of AIP is key for AIP patients. After that, clinicians can take appropriate treatment measures for those patients, which is helpful for the prognosis of AIP.