Spleen and splenic vascular involvement in acute pancreatitis: an MRI study

Small Bowel Obstruction as a Complication of Acute Pancreatitis

Epigastric pain and vomiting are common presentations associated with various causes of acute abdomen. Acute abdomen encompasses a range of different pathologies, with epigastric pain narrowing the differential diagnosis to conditions such as pancreatitis, bowel obstruction, acute cholecystitis, gastritis, acute coronary syndrome (ACS), and peptic ulcer disease, such as gastric ulcers and duodenal ulcers with/without perforation. This is a case of a male patient in his 80s who came to the emergency department with symptoms of generalized abdominal pain, vomiting, and constipation. Initial investigations and imaging supported a diagnosis of acute pancreatitis complicated by bowel obstruction. The patient was subsequently referred to the surgical team for further management.

Development and validation of a nomogram based on Lasso-Logistic regression for predicting splenomegaly secondary to acute pancreatitis

PURPOSE

Investigate the clinical characteristics of splenomegaly secondary to acute pancreatitis (SSAP) and construct a nomogram prediction model based on Lasso-Logistic regression.

METHODS

A retrospective case-control study was conducted to analyze the laboratory parameters and computed tomography (CT) imaging of acute pancreatitis (AP) patients recruited at Xuanwu Hospital from December 2014 to December 2021. Lasso regression was used to identify risk factors, and a novel nomogram was developed. The performance of the nomogram in discrimination, calibration, and clinical usefulness was evaluated through internal validation.

RESULTS

The prevalence of SSAP was 9.2% (88/950), with the first detection occurring 65(30, 125) days after AP onset. Compared with the control group, the SSAP group exhibited a higher frequency of persistent respiratory failure, persistent renal failure, infected pancreatic necrosis, and severe AP, along with an increased need for surgery and longer hospital stay (P < 0.05 for all). There were 185 and 79 patients in the training and internal validation cohorts, respectively. Variables screened by Lasso regression, including platelet count, white blood cell (WBC) count, local complications, and modified CT severity index (mCTSI), were incorporated into the Logistic model. Multivariate analysis showed that WBC count ≦9.71 × 109/L, platelet count ≦140 × 109/L, mCTSI ≧8, and the presence of local complications were independently associated with the occurrence of SSAP. The area under the receiver operating characteristic curve was 0.790. The Hosmer-Lemeshow test showed that the model had good fitness (P = 0.954). Additionally, the nomogram performed well in the internal validation cohorts.

CONCLUSIONS

SSAP is relatively common, and patients with this condition often have a worse clinical prognosis. Patients with low WBC and platelet counts, high mCTSI, and local complications in the early stages of the illness are at a higher risk for SSAP. A simple nomogram tool can be helpful for early prediction of SSAP.

Analysis of risk factors for acute pancreatitis complicated with pancreatic sinistral portal hypertension and construction of predictive model

Objective: Pancreatic sinistral portal hypertension (PSPH) is a common complication of acute pancreatitis (AP) and can cause massive gastrointestinal bleeding, which is one of the causes of AP-related mortality. However, there is currently no predictive model for AP concurrent with PSPH. This study aimed to identify the risk factors for AP concurrent with PSPH and use these factors to build a related predictive model. Materials and methods: We collected clinical data from 282 patients with AP. 192 patients were used as a training group and 90 patients as a validation group. Univariate and multivariate analyses were used to identify independent risk factors for AP complicated with PSPH, and then a nomogram was established. The models are cross verification and Internal verification. The predictive ability and accuracy of the model were evaluated based on the working curve of the subjects and the calibration curve, respectively. The clinical value of the model was evaluated using decision curve analysis (DCA). Results: The univariate analysis revealed significant differences in the occurrence of PSPH with respect to sex, recurrent AP, history of hypertension, smoking history, patency of the splenic vein, pancreatic necrosis or pancreatic pseudocyst formation, the most significant site of pancreatic swelling, presence of a Dmure D polymer, MCTSI, and involvement of lipase and amylase. The logistic multivariate regression analysis showed that male sex, splenic-vein stenosis or occlusion and swelling were located in the body-tail, and MCTSI was an independent risk factor for PSPH. The nomogram and ROC curve were constructed. The area under the working curve of the subjects was 0.91, and the sensitivity and specificity were 82.5% and 89.1%, respectively. In the validation group, the C-index is 0.826. The nomogram was internally validated using 1,000 bootstrap samples, and the c-index was 0.898. The calibration curve demonstrated that the predicted probability was concordant with the observed probability, and the DCA confirmed that the model had robust clinical utility. Conclusion: Male sex, splenic-vein stenosis or occlusion, recurrent AP, and swelling are located in the body-tail, and MCTSI is an independent risk factor for the occurrence of PSPH. The predictive model developed for AP complicated with PSPH may serve toward developing preventive and therapeutic approaches for PSPH.

Intravoxel incoherent motion diffusion-weighted MRI for the evaluation of early spleen involvement in acute leukemia

Background

The spleen is a frequent organ of leukemia metastasis. This study aimed to investigate the value of intravoxel incoherent motion (IVIM) diffusion-weighted magnetic resonance imaging (MRI) for assessing pathologic changes in the spleen and identifying early spleen involvement in patients with acute leukemia (AL).

Methods

Patients with newly diagnosed AL and healthy controls were recruited between June 2020 and November 2022. All participants underwent abdominal IVIM diffusion-weighted imaging (DWI) at our hospital. IVIM parameters [pure diffusion coefficient (D); pseudo-diffusion coefficient (D*); and pseudo-perfusion fraction (f)] of the spleen were calculated by the segmented fitting method, and perfusion-diffusion ratio (PDR) was further calculated from the values of D, D* and f. Spleen volumes (SVs) were obtained by manually segmenting the spleen layer by layer. Clinical biomarkers of AL patients were collected. Patients were divided into splenomegaly group and normal SV group according to the individualized reference intervals for SV. IVIM parameters were compared among the control group, AL with normal SV group, and AL with splenomegaly group using one-way analysis of variance, followed by pairwise post hoc comparisons. The correlations of IVIM parameters with clinical biomarkers were analyzed in AL patients. The diagnostic performances of IVIM parameters and their combinations for differentiating among the three groups were compared.

Results

Seventy-nine AL patients (AL with splenomegaly: n=54; AL with normal SV: n=25) and 55 healthy controls were evaluated. IVIM parameters were significantly different among the three groups (P<0.001 for D, D* and f; P=0.001 for PDR). D and PDR showed significant differences between the control and AL with normal SV groups in pairwise comparisons (P<0.001, and P=0.031, respectively). D was correlated with white blood cell (WBC) counts (r=-0.424; 95% CI: -0.570, -0.211; P<0.001), lactate dehydrogenase (LDH) (r=-0.285; 95% CI: -0.486, -0.011; P=0.011), and bone marrow blasts (r=-0.283; 95% CI: -0.476, -0.067; P=0.012). D* (r=-0.276; 95% CI: -0.470, -0.025; P=0.014), f (r=0.514; 95% CI: 0.342, 0.664; P<0.001) and PDR (r=0.343; 95% CI: 0.208, 0.549; P=0.002) were correlated with LDH. The combination of IVIM parameters (AUC: 0.830; 95% CI: 0.729, 0.905) demonstrated better diagnostic efficacy than the single D* (AUC: 0.721; 95% CI: 0.608, 0.816; Delong test: Z=2.012, P=0.044) and f (AUC: 0.647; 95% CI: 0.532, 0.752; Delong test: Z=2.829, P=0.005), but was not significantly different from the single D (AUC: 0.756; 95% CI: 0.647, 0.846; Delong test: Z=1.676, P=0.094) in differentiating the splenomegaly group and normal SV group.

Conclusions

IVIM diffusion-weighted MRI could be a potential alternative for assessing pathologic changes in the spleen from cellularity and angiogenesis, and D and PDR may be viable indicators to identify early spleen involvement in patients with AL.

Acute pancreatitis: A review of diagnosis, severity prediction and prognosis assessment from imaging technology, scoring system and artificial intelligence

Acute pancreatitis (AP) is a potentially life-threatening inflammatory disease of the pancreas, with clinical management determined by the severity of the disease. Diagnosis, severity prediction, and prognosis assessment of AP typically involve the use of imaging technologies, such as computed tomography, magnetic resonance imaging, and ultrasound, and scoring systems, including Ranson, Acute Physiology and Chronic Health Evaluation II, and Bedside Index for Severity in AP scores. Computed tomography is considered the gold standard imaging modality for AP due to its high sensitivity and specificity, while magnetic resonance imaging and ultrasound can provide additional information on biliary obstruction and vascular complications. Scoring systems utilize clinical and laboratory parameters to classify AP patients into mild, moderate, or severe categories, guiding treatment decisions, such as intensive care unit admission, early enteral feeding, and antibiotic use. Despite the central role of imaging technologies and scoring systems in AP management, these methods have limitations in terms of accuracy, reproducibility, practicality and economics. Recent advancements of artificial intelligence (AI) provide new opportunities to enhance their performance by analyzing vast amounts of clinical and imaging data. AI algorithms can analyze large amounts of clinical and imaging data, identify scoring system patterns, and predict the clinical course of disease. AI-based models have shown promising results in predicting the severity and mortality of AP, but further validation and standardization are required before widespread clinical application. In addition, understanding the correlation between these three technologies will aid in developing new methods that can accurately, sensitively, and specifically be used in the diagnosis, severity prediction, and prognosis assessment of AP through complementary advantages.

Quantitative tumor burden imaging parameters of the spleen at MRI for predicting treatment response in patients with acute leukemia

Objectives

To study the value of standardized volume and intravoxel incoherent motion (IVIM) parameters of the spleen based on tumor burden for predicting treatment response in newly diagnosed acute leukemia (AL).

Methods

Patients with newly diagnosed AL were recruited and underwent abdominal IVIM diffusion-weighted imaging within one week before the first induction chemotherapy. Quantitative parameters of magnetic resonance imaging (MRI) included the standardized volume (representing volumetric tumor burden) and IVIM parameters (standard apparent diffusion coefficient [sADC]; pure diffusion coefficient [D]; pseudo-diffusion coefficient [D∗]; and pseudo-perfusion fraction [f], representing functional tumor burden) of the spleen. Clinical biomarkers of tumor burden were collected. Patients were divided into complete remission (CR) and non-CR groups according to the treatment response after the first standardized induction chemotherapy, and the MRI and clinical parameters were compared between the two groups. The correlations of MRI parameters with clinical biomarkers were analyzed. Multivariate logistic regression was performed to determine the independent predictors for treatment response. Receiver operating characteristic curves were used to analyze the predicted performance.

Results

76 AL patients (CR: n = 43; non-CR: n = 33) were evaluated. Standardized spleen volume, sADC, D, f, white blood cell counts, and lactate dehydrogenase were significantly different between CR and non-CR groups (all p < 0.05). Standardized spleen volume, sADC, and D were correlated with white blood cell and lactate dehydrogenase, and f was correlated with lactate dehydrogenase (all p < 0.05). Standardized spleen volume (hazard ratio = 4.055, p = 0.042), D (hazard ratio = 0.991, p = 0.027), and f (hazard ratio = 1.142, p = 0.008) were independent predictors for treatment response, and the combination of standardized spleen volume, D, and f showed more favorable discrimination (area under the curve = 0.856) than individual predictors.

Conclusion

Standardized volume, D, and f of the spleen could be used to predict treatment response in newly diagnosed AL, and the combination of morphological and functional parameters would further improve the predicted performance. IVIM parameters of the spleen may be viable indicators for evaluating functional tumor burden in AL.

Predicting Severity of Acute Pancreatitis

Acute pancreatitis has a diverse etiology and natural history, and some patients have severe complications with a high risk of mortality. The prediction of the severity of acute pancreatitis should be achieved by a careful ongoing clinical assessment coupled with the use of a multiple-factor scoring system and imaging studies. Over the past 40 years, various scoring systems have been suggested to predict the severity of acute pancreatitis. However, there is no definite and ideal scoring system with a high sensitivity and specificity. The interest in new biological markers and predictive models for identifying severe acute pancreatitis testifies to the continued clinical importance of early severity prediction. Although contrast-enhanced computed tomography (CT) is considered the gold standard for diagnosing pancreatic necrosis, early scanning for the prediction of severity is limited because the full extent of pancreatic necrosis may not develop within the first 48 h of presentation. This article provides an overview of the available scoring systems and biochemical markers for predicting severe acute pancreatitis, with a focus on their characteristics and limitations.

Incidence and treatment of splanchnic vein thrombosis in patients with acute pancreatitis: A systematic review and meta-analysis

BACKGROUND AND AIM

This meta-analysis aimed to estimate the incidence of splanchnic vein thrombosis (SVT) in patients with acute pancreatitis and assess the effects of therapeutic anticoagulation.

METHODS

Systematic searches of the Medline, Embase, and Cochrane databases were undertaken to identify studies reporting the incidence and outcomes associated with SVT in patients with acute pancreatitis. The pooled incidence, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effects model. PROSPERO database registration no. CRD 42021230912.

RESULTS

Only 18 of the 238 studies identified met the inclusion criteria. Of the 943 patients who had SVT, 264 (28.0%) received anticoagulation. The pooled incidence of SVT at first presentation of acute pancreatitis was 15% (95% CI 5 to 26%), but was 17% (95% CI 14 to 20%) in all studies. Recanalization was more likely to occur in the anticoagulation-treated than in the untreated group (OR 0.51, 95% CI 0.31 to 0.83, P = 0.007). There were no differences in hemorrhagic complications (OR 2.27, 95% CI 0.81 to 6.37, P = 0.12) or overall mortality (OR 2.37, 95% CI 0.86 to 6.52, P = 0.10) in relation to the use of anticoagulation. The overall incidence of portal hypertension in patients was 60% (95% CI 55 to 65%). However, it was not possible to determine the incidence in each group.

CONCLUSIONS

The incidence of SVT in patients with acute pancreatitis is significant. Treatment with anticoagulants improved the odds of recanalization but did not increase the risk of hemorrhagic complications or overall mortality.

Effects of Indwelling Pleural Catheter on Severe Acute Pancreatitis: A Retrospective Study

Background. Pleural effusion (PE) is an important predictor for severity and prognosis of severe acute pancreatitis (SAP). However, there are few studies focused on the effects and timing of indwelling pleural catheter (IPC) on SAP. Considering this, we designed a retrospective study to verify the relationship between PE and severity of SAP and observe the effects and timing of IPC in SAP. Methods. A total of 309 SAP patients were enrolled. Based on the presence or absence of PE and IPC and IPC time, the enrolled patients were divided into 6 groups. Then, baseline parameters, disease severity, critical complications, ventilator supporting time (VST), length of stay (LOS), and 60-day mortality were compared between each two groups. Results. PE was a risk factor for death of SAP, but not an independent risk factor. SAP patients with PE rather without PE had higher critical complication rates ( $p<0.001$ ), along with longer VST ( $p<0.001$ ) and LOS ( $p<0.001$ ). And the critical complication rates were lower in group 1 (IPC within 1 week of onset) than group 2 (IPC after 1 week of onset). Further, patients in group 1 also had shorter LOS ( $p=0.042$ ) and VST ( $p=0.001$ ) than those in group 2. In addition, the survival analysis showed the risk of death in the PE group was higher than the non-PE group (HR 6.6, 95% CI, 3.67–11.86, and $p<0.001$ ). And the risk of death in group 1 was lower than group 2 (HR 0.26, 95% CI, 0.08–0.84, and $p=0.025$ ). Conclusions. PE is a risk factor for death of SAP, but not an independent risk factor. IPC, especially IPC within 1 week of onset, has clinical practical value in SAP.

Vascular Complications in Pediatric Pancreatitis: A Case Series

We reviewed INSPPIRE (International Study Group of Pediatric Pancreatitis: In Search for a Cure) database for splanchnic venous thrombosis or arterial pseudoaneurysms to determine the incidence, risk factors and outcomes of peripancreatic vascular complications in children with acute recurrent pancreatitis (ARP) or chronic pancreatitis (CP). Of 410 children with diagnostic imaging studies, vascular complications were reported in five (1.2%); two had ARP, three CP. The vascular events were reported during moderately severe or severe acute pancreatitis (AP) in four, mild AP in one. Venous thrombosis occurred in four, arterial pseudoaneurysm (left gastric artery) in one. Two patients with venous thrombosis were treated with anticoagulant, one achieved recanalization (splenic vein). In two patients who did not receive anticoagulants, one re-canalized. No adverse effects were observed with anticoagulants. The child with pseudoaneurysm underwent aneurysmal coiling. Anti-coagulants appear to be safe in children with acute pancreatitis, their long-term benefit needs to be further investigated.

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.

Magnetic resonance severity index assessed by T1-weighted imaging for acute pancreatitis: correlation with clinical outcomes and grading of the revised Atlanta classification-a narrative review

Acute pancreatitis (AP) is a common disease that may involve pancreas and peripancreatic tissues with a prevalence of up to 50 per 100,000 individuals for year. The Atlanta classification was assessed for the first time in 1992 and modified in 2012 in order to describe morphological features of AP and its complications. AP can be morphologically distinguished in two main types: interstitial edematous pancreatitis (IEP) and necrotizing pancreatitis (NEP). This classification is very important because the presence of necrosis is directly linked to local or systemic complications, hospital stays and death. Magnetic resonance (MR) is very useful to characterize morphological features in AP and its abdominal complications. Particularly we would like to underline the diagnostic, staging and prognostic role of T1-weighted images with fat suppression that could be significant to assess many features of the AP inflammatory process and its complications (detection of the pancreatic contour, pancreatic necrosis, presence of haemorrhage). Signs of inflammatory and edema are instead observed by T1-weighted images. MR cholangiopancreatography (MRCP) is necessary to study the main pancreatic duct and the extrahepatic biliary tract and contrast-enhancement magnetic resonance imaging (MRI) allows to assess the extent of necrosis and vascular injuries.

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.

Chest computed tomography semi-quantitative pleural effusion and pulmonary consolidation are early predictors of acute pancreatitis severity

Background

To study the predictive value of semi-quantitative pleural effusion and pulmonary consolidation for acute pancreatitis (AP) severity.

Methods

Thorax-abdominal computed tomography (CT) examinations were performed on 309 consecutive AP patients in a single center. Among them, 196 were male, and 113 were female, and the average age was 50±16 years. The etiology of AP was biliary in 43.7% (n=135), hyperlipidemia in 22.0% (n=68), alcoholic in 7.4% (n=23), trauma in 0.6% (n=2), and postoperative status in 1.6% (n=5) cases; 24.6% (n=76) of patients did not have specified etiologies. The prevalence of pleural effusion and pulmonary consolidation was noted. The pleural effusion volume was quantitatively derived from a CT volume evaluation software tool. The pulmonary consolidation score was based on the number of lobes involved in AP. Each patient's CT severity index (CTSI), acute physiology and chronic health evaluation II (APACHE II) scoring system, and bedside index for severity in acute pancreatitis (BISAP) scores were obtained. The semi-quantitative pleural effusion and pulmonary consolidation were compared to these scores and clinical outcomes by receiver operator characteristic (ROC) curve and area under the curve (AUC) analysis.

Results

In the 309 patients, 39.8% had pleural effusion, and 47.9% had pulmonary consolidation. The mean pleural effusion volume was 41.7±38.0 mL. The mean pulmonary consolidation score was 1.0±1.2 points. The mean CTSI was 3.7±1.8 points, the mean APACHE II score was 5.8±5.1 points, and the mean BISAP score was 1.3±1.0 points; 5.5% of patients developed severe AP, and 13.9% of patients developed organ failure. Pleural effusion volume and pulmonary consolidation scores correlated to the scores for the severity of AP. In predicting severe AP, the accuracy (AUC 0.839) of pleural effusion volume was similar to that of the CTSI score (P=0.961), APACHE II score (P=0.757), and BISAP score (P=0.906). The accuracy (AUC 0.805) of the pulmonary consolidation score was also similar to that of the CTSI score (P=0.503), APACHE II score (P=0.343), and BISAP score (P=0.669). In predicting organ failure, the accuracy (AUC 0.783) of pleural effusion volume was similar to that of the CTSI score (P=0.473), APACHE II score (P=0.119), and BISAP score (P=0.980), and the accuracy (AUC 0.808) of the pulmonary consolidation score was also similar to that of the CTSI score (P=0.236), APACHE II score (P=0.293), and BISAP score (P=0.612).

Conclusions

Pleural effusion and pulmonary consolidation are common in AP and correlated to the severity of AP. Furthermore, the pleural effusion volume and pulmonary consolidation lobes can provide early prediction of severe AP and organ failure.

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.

MR imaging for acute pancreatitis: the current status of clinical applications

Acute pancreatitis is a common clinical acute abdomen. Imaging examinations play an important role in the management of acute pancreatitis. MR imaging is a noninvasive examination with high tissue contrast and a variety of acquisition sequences that can help determine the diagnosis, complications and severity of acute pancreatitis. The acute pancreatitis classification working group modified the Atlanta classification in 2012 to improve clinical evaluations and standardize the radiologic nomenclature for acute pancreatitis. In particular, the redefinition of necrotizing pancreatitis offers a new understanding of this disease. In clinical practice, there is still a lack of unifying standards between radiologists and physicians, such as for the imaging features of pseudocysts, walled-off necrosis, peripancreatic necrosis and especially for the MR imaging features of acute pancreatitis. In this article, we review the 2012 revised Atlanta classification of acute pancreatitis and recent advances in the clinical applications of MR imaging (MRI) in acute pancreatitis by showing how MRI can provide more optimized information for clinical diagnosis and treatment plan.

Visualization of the fat planes between the pancreas and the adjacent organs and blood vessels using multi-detector computed tomography

PURPOSE

To explore individual variations in visibility of the fat planes between the pancreatic parenchyma and adjacent organs and blood vessels using the multi-detector-computed tomography (MDCT).

METHODS

Abdominal contrast-enhanced MDCT examinations of 520 consecutive adult individuals were retrospectively analysed by exploring the presence of visible fat planes between the healthy pancreas and the following surrounding structures: stomach, descending duodenum (D2), splenic, portal, superior mesenteric vein (SV, PV, SMV), inferior vena cava (IVC), and coeliac trunk, common hepatic and superior mesenteric artery (CT, HA and SMA). Spearman's rank correlation coefficient (r_S) was used to assess the correlation of individual gender, age, body mass and BMI, and visible fat planes towards particular surrounding structures.

RESULTS

Fat planes between the pancreatic parenchyma and surrounding structures was visible as follows: stomach in 76%, D2 11.7%, SV 51.5%, PV 0%, SMV 28.8%, IVC 80.8%, CT 99.4%, HA 90.4% and SMA in 100% participants. The presence of visible fat planes significantly correlated (p < 0.001) with body mass for stomach (r_S = 0.367), D2 (r_S = 0.247), SV (r_S = 0.355), SMV (r_S = 0.384) and IVC (r_S = 0.259); BMI for stomach (r_S = 0.292), SV (r_S = 0.248), SMV (r_S = 0.290) and IVC (r_S = 0.216); age for D2 (r_S = 0.363), SV (r_S = 0.276) and SMV (r_S = 0.409); and male gender for stomach (r_S = 0.160) and SV (r_S = 0.198).

CONCLUSION

Fat planes around the pancreatic parenchyma in the MDCT scan was almost always visible towards the adjacent magistral visceral arteries and IVC, always invisible towards the PV, and variably visible towards the SV, SMV, stomach and duodenum depending on the individual body mass, BMI, age and gender.