Suspected early or mild chronic pancreatitis: enhancement patterns on gadolinium chelate dynamic MRI. Magnetic resonance imaging

Dynamic contrast-enhanced (DCE) imaging: state of the art and applications in whole-body imaging

Dynamic contrast-enhanced (DCE) imaging is a non-invasive technique used for the evaluation of tissue vascularity features through imaging series acquisition after contrast medium administration. Over the years, the study technique and protocols have evolved, seeing a growing application of this method across different imaging modalities for the study of almost all body districts. The main and most consolidated current applications concern MRI imaging for the study of tumors, but an increasing number of studies are evaluating the use of this technique also for inflammatory pathologies and functional studies. Furthermore, the recent advent of artificial intelligence techniques is opening up a vast scenario for the analysis of quantitative information deriving from DCE. The purpose of this article is to provide a comprehensive update on the techniques, protocols, and clinical applications - both established and emerging - of DCE in whole-body imaging.

Pancreatitis and PDAC: association and differentiation

The discrimination of mass-forming chronic pancreatitis (MFCP) from pancreatic ductal adenocarcinoma (PDAC) is a central diagnostic dilemma. It is important to differentiate these entities since they have markedly different prognoses and management. Importantly, the appearance of these two entities significantly overlaps on a variety of imaging modalities. However, there are imaging features that may be suggestive of one entity more than the other. MFCP and PDAC may show different enhancement patterns on perfusion computed tomography (CT) and/or dynamic contrast-enhanced MRI (DCE-MRI). The duct-penetrating sign on magnetic resonance cholangiopancreatography (MRCP) is more often associated with MFCP, whereas abrupt cutoff with upstream dilatation of the main pancreatic duct and the double-duct sign (obstruction/cutoff of both the common bile duct and pancreatic duct) are more often associated with PDAC. Nevertheless, tissue sampling is the most reliable method to differentiate between these entities and is currently generally necessary for management.

Cross-sectional imaging-based severity scoring of chronic pancreatitis: why it is necessary and how it can be done

Chronic pancreatitis (CP) remains a diagnostic challenge as clinical symptoms are non-specific, histopathological appearances are varied and pathogenesis remains incompletely understood. Multiple classifications and grading systems have been proposed for CP, but none leverage the full capabilities of cross-sectional imaging modalities and are not widely accepted or validated. CT and MRI/MRCP are useful in identifying a wide spectrum of histopathological changes in CP and can also assess exocrine reserve of pancreas. Advanced MRI techniques such as T1 mapping and extracellular volume fraction can potentially identify early CP. Cross-sectional imaging-based severity scoring can quantify CP disease burden and may have positive implications for clinicians and researchers. In this review, we discuss the need for cross-sectional imaging-based severity scoring for CP, role of CT, and MRI/MRCP in assessment of CP and how these modalities can be used to obtain severity scoring for CP. We summarize relevant information from recently published CT and MRI/MRCP reporting standards for CP, and from international guidelines for cross-sectional imaging and severity scoring for CP.

Imaging in chronic pancreatitis: State of the art review

Chronic pancreatitis (CP) is an important gastrointestinal cause of morbidity worldwide. It can severely impair the quality of life besides life-threatening acute and long-term complications. Pain and pancreatic exocrine insufficiency (leading to malnutrition) impact the quality of life. Acute complications include pseudocysts, pancreatic ascites, and vascular complications. Long-term complications are diabetes mellitus and pancreatic cancer. Early diagnosis of CP is crucial to alter the natural course of the disease. However, majority of the cases are diagnosed in the advanced stage. The role of various imaging techniques in the diagnosis of CP is discussed in this review.

Guidelines for the Diagnostic Cross Sectional Imaging and Severity Scoring of Chronic Pancreatitis

The paper presents the international guidelines for imaging evaluation of chronic pancreatitis. The following consensus was obtained: Computed tomography (CT) is often the most appropriate initial imaging modality for evaluation of patients with suspected chronic pancreatitis (CP) depicting most changes in pancreatic morphology. CT is also indicated to exclude other potential intraabdominal pathologies presenting with symptoms similar to CP. However, CT cannot exclude a diagnosis of CP nor can it be used to exclusively diagnose early or mild disease. Here magnetic resonance imaging (MRI) and MR cholangiopancreatography (MRCP) is superior and is indicated especially in patients where no specific pathological changes are seen on CT. Secretin-stimulated MRCP is more accurate than standard MRCP in the depiction of subtle ductal changes. It should be performed after a negative MRCP, when there is still clinical suspicion of CP. Endoscopic ultrasound (EUS) can also be used to diagnose parenchymal and ductal changes mainly during the early stage of the disease. No validated radiological severity scoring systems for CP are available, although a modified Cambridge Classification has been used for MRCP. There is an unmet need for development of a new and validated radiological CP severity scoring system based on imaging criteria including glandular volume loss, ductal changes, parenchymal calcifications and parenchymal fibrosis based on CT and/or MRI. Secretin-stimulated MRCP in addition, can provide assessment of exocrine function and ductal compliance. An algorithm is presented, where these imaging parameters can be incorporated together with clinical findings in the classification and severity grading of CP.

Morphological and functional changes of chronic pancreatitis in patients with dyspepsia: A prospective, observational, cross-sectional study

OBJECTIVE

Whether chronic pancreatitis (CP) may present with dyspepsia is controversial. We aimed at evaluating the frequency and risk factors of changes of CP in patients presenting with epigastric pain syndrome (EPS)-like symptoms.

DESIGN

A prospective, observational, cross-sectional study was carried out in patients with EPS-like symptoms. Patients underwent endoscopic ultrasound (EUS) evaluation of the pancreas, and changes of CP were defined as the presence of five or more EUS criteria of the disease. In patients with 3 or 4 EUS criteria, magnetic resonance dynamic evaluation of the pancreas (MRI/sMRCP) and endoscopic pancreatic function test (ePFT) were carried out to confirm or exclude the presence of changes of CP. A multivariate logistic regression analysis was performed to evaluate factors associated with CP findings, and results are shown as odds ratio (OR) and 95% confidence interval (CI).

RESULTS

213 patients were included. Changes of CP were confirmed by EUS (≥5 criteria) in 18 patients (8.4%). Thirty-four patients had 3-4 EUS criteria, and changes of CP were confirmed in 27 of them by MRI/sMRCP and ePFT (12.7%). Morphological and functional findings of CP were then present in 45 patients (21.1%). Male gender (OR 2.97; 95%CI 1.39-6.37) and alcohol and tobacco consumption (OR 6.56; 95%CI 1.97-21.85) were associated with the presence of changes of CP.

CONCLUSION

Morphological and functional changes of CP are frequent in patients with EPS-like symptoms. Whether these pancreatic changes explain EPS-like symptoms requires further investigation.

Diagnostic performance of imaging modalities in chronic pancreatitis: a systematic review and meta-analysis

OBJECTIVES

Obtain summary estimates of sensitivity and specificity for imaging modalities for chronic pancreatitis (CP) assessment.

METHODS

A systematic search was performed in Cochrane Library, MEDLINE, Embase and CINAHL databases for studies evaluating imaging modalities for the diagnosis of CP up to September 2016. A bivariate random-effects modeling was used to obtain summary estimates of sensitivity and specificity.

RESULTS

We included 43 studies evaluating 3460 patients. Sensitivity of endoscopic retrograde cholangiopancreatography (ERCP) (82%; 95%CI: 76%-87%) was significant higher than that of abdominal ultrasonography (US) (67%; 95%CI: 53%-78%; P=0.018). The sensitivity estimates of endoscopic ultrasonography (EUS), magnetic resonance imaging (MRI), and computed tomography (CT) were 81% (95%CI: 70%-89%), 78% (95%CI: 69%-85%), and 75% (95%CI: 66%-83%), respectively, and did not differ significantly from each other. Estimates of specificity were comparable for EUS (90%; 95%CI: 82%-95%), ERCP (94%; 95%CI: 87%-98%), CT (91%; 95% CI: 81%-96%), MRI (96%; 95%CI: 90%-98%), and US (98%; 95%CI: 89%-100%).

CONCLUSIONS

EUS, ERCP, MRI and CT all have comparable high diagnostic accuracy in the initial diagnosis of CP. EUS and ERCP are outperformers and US has the lowest accuracy. The choice of imaging modality can therefore be made based on invasiveness, local availability, experience and costs.

KEY POINTS

• EUS, ERCP, MRI and CT have high diagnostic sensitivity for chronic pancreatitis • Diagnostic specificity is comparable for all imaging modalities • EUS and ERCP are outperformers and US has the lowest accuracy • The choice of imaging can be made based on clinical considerations.

Surgical approaches to chronic pancreatitis: indications and imaging findings

Chronic pancreatitis (CP) is an irreversible, inflammatory process characterized by progressive fibrosis of the pancreas that can result in abdominal pain, exocrine insufficiency, and diabetes. Inadequate pain relief using medical and/or endoscopic therapies is an indication for surgery. The surgical management of CP is centered around three main operations including pancreaticoduodenectomy (PD), duodenum-preserving pancreatic head resection (DPPHR) and drainage procedures, and total pancreatectomy with islet autotransplantation (TPIAT). PD is the method of choice when there is a high suspicion for malignancy. Combined drainage and resection procedures are associated with pain relief, higher quality of life, and superior short-term and long-term survival in comparison with the PD. TPIAT is a reemerging treatment that may be promising in subjects with intractable pain and impaired quality of life. Imaging examinations have an extensive role in pre-operative and post-operative evaluation of CP patients. Pre-operative advanced imaging examinations including CT and MRI can detect hallmarks of CP such as calcifications, pancreatic duct dilatation, chronic pseudocysts, focal pancreatic enlargement, and biliary ductal dilatation. Post-operative findings may include periportal hepatic edema, pneumobilia, perivascular cuffing and mild pancreatic duct dilation. Imaging can also be useful in the detection of post-operative complications including obstructions, anastomotic leaks, and vascular lesions. Imaging helps identify unique post-operative findings associated with TPIAT and may aid in predicting viability and function of the transplanted islet cells. In this review, we explore surgical indications as well as pre-operative and post-operative imaging findings associated with surgical options that are typically performed for CP patients.

Evaluation of Qualitative Magnetic Resonance Imaging Features for Diagnosis of Chronic Pancreatitis

OBJECTIVES

The purpose of this study was to determine qualitative pancreatic magnetic resonance imaging (MRI) features that must be present to predict abnormal pancreatic secretory function in patients evaluated for chronic pancreatitis (CP).

METHODS

The MRIs of study subjects were reviewed by 2 abdominal radiologists; qualitative parenchyma and ductal features were recorded. Endoscopic pancreatic function test (ePFT) results (reference standard) were classified as normal (peak pancreatic fluid bicarbonate [HCO3-] ≥75 meq/L) or abnormal (<75). Abnormal ePFT was further classified as mild/moderate (74-65) and marked deficiency (<65). Statistical analysis was performed to assess the association between MRI features and abnormal ePFT.

RESULTS

The study cohort was composed of 93 subjects, mean age 49 years (range, 18-78 years), 65% females. Univariate analysis identified 9 qualitative MRI features significantly (P < 0.05) associated with abnormal pancreatic secretory function. Number of MRI features increases as peak pancreatic fluid [HCO3-] decreases (Pearson r = -0.629; P = 0.001). Receiver operating characteristic curve analysis determined that a threshold of 6 or more associated MRI features 64% sensitive and 94% specific for marked bicarbonate deficiency.

CONCLUSIONS

Qualitative MRI parenchymal and ductal features are associated with CP. Presence of 6 or more features results in a higher specificity for the diagnosis of CP in advanced disease.

Utility of Contrast-Enhanced Transabdominal Ultrasonography to Diagnose Early Chronic Pancreatitis

Purpose. The purpose of this study was to establish the relationship between the grade of chronic pancreatitis (CP) and pancreatic blood flow as measured by contrast-enhanced transabdominal ultrasonography (CEUS) and to diagnose early CP easily. Methods. This pilot study was conducted in 8 patients with CP, 7 patients with early CP, and 6 control participants. After injecting 0.015 mL/kg of perflubutane by manual bolus, values in one region of interest (ROI) in pancreatic parenchyma and one ROI including the superior mesenteric artery (SMA) were measured. Results. The ratio of blood flow in the SMA and pancreatic parenchyma increased with grade of CP and was significantly higher in patients with CP (5.41; 2.10–11.02) than in patients with early CP (2.46; 1.41–5.05) and control participants (2.32; 1.25–3.04) (P = 0.0279, P = 0.0142, resp.). The ratio of blood flow in the SMA and pancreatic parenchyma correlated with grade of CP (rs = 0.5904, P = 0.0048). Conclusion. The ratio of blood flow correlates with grade of CP on CEUS. This safe and convenient method may be useful to diagnose early CP.

MRI prediction of islet yield for autologous transplantation after total pancreatectomy for chronic pancreatitis

OBJECTIVE

The relationship between magnetic resonance imaging (MRI), histopathology, and islet yield was examined for chronic pancreatitis patients undergoing total pancreatectomy and autologous islet cell transplant (TP-AIT) to determine if the yield can be predicted by pre-operative MRI.

METHODS

MRI sequences and histopathology were scored and compared for patients from whom ≤2,500 islet equivalents/kg were obtained with those from whom >2,500 islet equivalents/kg were obtained.

RESULTS

Twenty patients, 14 female, mean age 40.20 ± 12.5 years, (range 19-63) underwent MRI before TP-AIT; mean 3,724 ± 891 islet equivalents/kg body weight, median 2,970, (range 76-17,770) were procured. There was no correlation between islet cell numbers and pancreas weight, HgbA1c, or c-peptide. The most common MRI sequence abnormality was the delayed interstitial phase, 14/18 (78 %). The other common MRI sequence abnormalities were, precontrast T1W 3D GRE sequence, 13/19 (68 %), and the arterial perfusion phase, 11/18 (61 %). The pancreatic duct was dilated in 10/20 (50 %). Parenchymal atrophy was noted in 10/20 (50 %). Median scores for individual MRI sequences were greater in patients with an islet cell yield of ≤2,500 islet equivalents/kg; for the delayed interstitial phase the difference was significant (median 2.5, range 1-3 versus median 0.5, range 0-3, P = 0.034). Histologically the most common feature was fibrosis, (17/17, 100 %); the score for fibrosis was greater for patients with an islet cell yield of ≤2,500 islet equivalents/kg (median 6.0, range 5-7 versus median 4.0, range 3-7, P = 0.024).

CONCLUSION

A diminished islet yield may be predicted on the basis of the delayed interstitial phase MRI sequence.

Assessment of Chronic Pancreatitis: Use of Whole Pancreas Perfusion With 256-Slice Computed Tomography

OBJECTIVE: We aimed to compare perfusion computed tomography (CTP) characteristics of the normal pancreas with those of chronic pancreatitis (CP) and to examine the possibility of evaluating pancreatic exocrine function with CTP. METHODS: Thirty-two patients (control group, n = 18; CP group, n = 14) who completed the whole pancreas CT perfusion examination with 256-slice CT were studied. Four parameters, including perfusion (PF), peak enhancement intensity (PEI), time-to-peak (TTP), and blood volume (BV), were measured and compared between the control and CP groups, and between patients with and without exocrine pancreatic insufficiency (EPI) in the CP group. Pancreatic exocrine function was determined via serum trypsinogen. RESULTS: There was no significant difference between the distribution of PF, PEI, and BV in different pancreas regions, namely, the head, body, and tail (P > 0.05). PF, PEI, and BV of the CP group were significantly decreased, and TTP was significantly increased compared with the control group (P < 0.05). A significant decrease of PF, PEI, and BV and increase of TTP were observed in patients with EPI than in patients without EPI (P < 0.05). CONCLUSIONS: Perfusion CT is an appropriate imaging technique to diagnose CP and may be useful as a screening test to rule out early EPI.

Update on the role of endoscopic ultrasound in chronic pancreatitis

Chronic pancreatitis (CP) remains an important healthcare problem that adversely affects quality of life. Endoscopic ultrasound (EUS) is a preferred test for the diagnosis of early CP. The Rosemont classification strictly defines and assigns weighting to the previously described ductal and parenchymal criteria. Recent histological correlation studies have improved our understanding of the accuracy of EUS criteria. Digital imaging analysis and complementary functional testing may complement endosonographic diagnosis. EUS-directed celiac plexus blockade and ductal access techniques have expanded the therapeutic armamentarium for pain management in CP.

Imaging of benign and malignant cystic pancreatic lesions and a strategy for follow up

Cystic lesions in a variety of organs are being increasingly recognized as an incidental finding on cross-sectional imaging. These lesions can be benign, premalignant or malignant. When these cystic lesions are small it can be difficult to characterize them radiologically. However, with appropriate clinical history and knowledge of typical imaging features of cystic pancreatic lesions this can enable accurate diagnosis and thus guide appropriate treatment. In this review, we provide an overview of the most common types of cystic lesions and their appearance on computer tomography, magnetic resonance imaging and ultrasound. We will also discuss the follow up and management strategies of these cystic lesions.

Pancreatic duct changes are not associated with early signs of chronic pancreatitis at magnetic resonance imaging (MRI) in patients with primary sclerosing cholangitis

OBJECTIVE

The association between chronic pancreatitis (CP) and primary sclerosing cholangitis (PSC) has been reported previously. The aims of the present study were to evaluate the presence of early pancreatic abnormalities and duct changes, using MRCP/MRI in PSC and to evaluate possible risk factors for these changes and their clinical importance.

MATERIALS AND METHODS

One hundred and three patients with PSC were identified among all MRI liver/pancreas referrals in 2001-2005. MRCP was used to grade pancreatic duct changes in three groups: grade 0 (normal), grade 1 (mild) and grade 2 (severe). For detection of early MRI signs of CP, the pancreas-spleen signal intensity ratio (SIR), the arterial and early venous phase ratio (A/PV ratio) and the age-related size of the pancreas were evaluated.

RESULTS

Pancreatic duct changes were found in 24% of the PSC patients. The pancreatic duct changes were associated with extrahepatic biliary involvement and long duration of PSC but not associated with pancreas-spleen SIR, A/PV ratio, pancreas size, previous post-ERCP or acute pancreatitis. Severe pancreatic duct changes were significantly associated to abdominal pain. Clinically significant CP was seen in one PSC patient (1%).

CONCLUSIONS

Pancreatic duct changes are associated with extrahepatic bile duct strictures and not with the early MRI signs of CP. Therefore, pancreatic duct changes seem to be part of the spectrum of PSC and should not be defined as CP. Pancreatic duct changes are of limited clinical importance but may contribute to abdominal pain in PSC.

MRI and S-MRCP findings in patients with suspected chronic pancreatitis: correlation with endoscopic pancreatic function testing (ePFT)

PURPOSE

To review magnetic resonance imaging (MRI) and secretin stimulated magnetic resonance cholangiopancreatography (S-MRCP) findings of patients with suspected chronic pancreatitis and compare them with endoscopic pancreatic function testing (ePFT).

MATERIALS AND METHODS

MRI and S-MRCP findings of 36 patients with clinically suspected chronic pancreatitis were reviewed. Baseline ductal changes, duodenal filling grades, and pancreatic duct caliber change (PDC) on S-MRCP, mean values of pancreatic anteroposterior (AP) diameter, signal intensity ratio (SIR) between pancreas and the spleen on T1-weighted fat saturated images, and arterial to venous (A/V) enhancement ratios were compared between groups of normal and abnormal pancreatic exocrine function determined by ePFT.

RESULTS

All patients (n = 24) with normal ePFT (HCO(3) >80 mEq/L) had grade 3 normal duodenal filling. Patients with abnormal ePFT (HCO(3) <80 mEq/L) (n = 12) had grade 1 (n = 1) and grade 2 (n = 11) diminished duodenal filling (P < 0.0001). PDC was 1.51 in the normal ePFT group versus 1.27 in the abnormal ePFT group (P = 0.01). No significant differences were found in terms of mean pancreatic AP diameter (21.8 vs. 19.8 cm), SIR (1.59 vs. 1.44), and A/V (1.08 vs. 1.01) between groups of normal/abnormal pancreatic exocrine function.

CONCLUSION

Despite discrepancies between pancreatic exocrine function and the findings on standard MRI/MRCP, the S-MRCP findings are comparable to ePFT in the evaluation of chronic pancreatitis.

MR imaging of cystic lesions of the pancreas

Pancreatic cystic lesions are relatively common imaging findings and may be secondary to both benign and malignant disease processes. Accurate characterization of the internal features of a cyst--including fluid, hemorrhage, septa, and enhancing soft-tissue components--is important to guide the differential diagnosis, and cross-sectional magnetic resonance (MR) imaging is the optimal modality for depicting these features. Cystic lesions of the pancreas may be divided into two categories: (a) primary cystic lesions, which include pseudocysts, serous cystadenomas, various mucin-containing cysts (mucinous nonneoplastic cysts, mucinous cystadenomas, mucinous cystadenocarcinomas, intraductal papillary mucinous neoplasms), and lymphoepithelial cysts, and (b) various solid neoplasms undergoing cystic changes (ductal adenocarcinoma with cystic features, pseudopapillary tumors of the pancreas, and cystic neuroendocrine tumors). Primary cystic lesions are more common than solid neoplasms with cystic changes. Knowledge of the varied MR imaging appearances of pancreatic cystic lesions may help radiologists achieve greater specificity in diagnostic reporting.

Pancreatic adenocarcinoma tumor grade determination using contrast-enhanced magnetic resonance imaging

OBJECTIVES

To determine whether the degree of enhancement of pancreatic adenocarcinoma visualized on arterial phase gadolinium-enhanced magnetic resonance imaging (MRI) correlates with the histopathological tumor grade.

METHODS

Thirty-nine patients with pancreatic adenocarcinoma had MRI within 14 days before tumor resection. Gadolinium-chelate-enhanced (Gd) 3-dimensional gradient echo images were acquired including the arterial phase. Tumor imaging patterns on the arterial phase images were classified for low, moderate, or high degree of enhancement and compared against conventional histological grading.

RESULTS

Based on histological grading, there were 12 poorly differentiated, 2 poorly to moderately differentiated, 22 moderately differentiated, and 3 well-differentiated adenocarcinomas. There was agreement between the MRI arterial enhancement pattern and histological grading in 30 of 39 cases. The mean size of tumors grouped by enhancement pattern or grade was not significantly different between groups. Although minor discordance was found in 9 of the 39 cases, statistical analysis showed agreement between the degree of arterial enhancement on MRI and histological tumor differentiation; the Cohen's kappa value was 0.64 with a 95% confidence interval of 0.46-0.83.

CONCLUSIONS

Pancreatic adenocarcinoma arterial phase enhancement correlates with the histological grade of differentiation.

Role of fat-suppressed t1-weighted magnetic resonance imaging in predicting severity and prognosis of acute pancreatitis: an intraindividual comparison with multidetector computed tomography

OBJECTIVE

To determine the diagnostic value of magnetic resonance (MR) grading focusing on elevated signal on T1-weighted images in the prediction of severity and prognosis of acute pancreatitis as compared with the Balthazar computed tomography (CT) grading.

MATERIALS

Thirty-one patients with acute pancreatitis who underwent CT and MR imaging including fat-suppressed T1-weighted images within a 48-hour interval were included in this study. The severity of pancreatitis was evaluated by 2 observers using the Balthazar CT grading system and an MR grading system that is focused on an elevated signal on T1-weighted images. The MR grading was correlated with the CT grading, and each MR or CT grade was compared with patient outcome parameters, including the duration of hospitalization, local and systemic complications, and clinical outcome grading.

RESULTS

There was a significant correlation between CT and MR gradings for pancreatic or peripancreatic inflammation (r = 0.688, P < 0.01). However, for all of the outcome parameters and outcome grading, a stronger correlation was seen with the MR grading than with the CT grading. No significant correlation was found between CT grading and infected necrosis (r = 0.316, P = 0.083).

CONCLUSIONS

Magnetic resonance imaging including fat-suppressed T1-weighted images is more accurate to predict the severity and prognosis of acute pancreatitis in comparison with CT.

DCE-MRI in experimental chronic pancreatitis

To assess pancreatic perfusion in experimental chronic pancreatitis (CP) by dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). DCE MRI on a 1.5 T MR scanner was performed on 21 piglets with the ligation of pancreatic duct. They were divided into four groups based on pathology, including seven normal pigs and seven, three and four piglets with grade I, II and III CP, respectively. The signal intensity measured in the pancreatic body on DCE MRI was plotted against time to create a signal intensity-time (SI-T) curve for each piglet. The steepest slope (SS), time-to-peak (TTP) and peak enhancement ratio (PER) of the SI-T curve were noted. In the four groups, on the SI-T curve derived from DCE MRI, the SS was, respectively, 10.88 +/- 1.20, 10.59 +/- 1.02, 6.67 +/- 1.31 and 5.48 +/- 1.97%/s (F = 20.509, p = 0.000) from normal piglets to piglets with grade III CP. The TTP was 13.82 +/- 3.09, 12.31 +/- 5.52, 20.55 +/- 3.79 and 37.26 +/- 14.56 s (F = 10.681, p = 0.000) and the PER was 62.95 +/- 20.20, 60.44 +/- 20.00, 46.33 +/- 22.70 and 67.65 +/- 32.66% (F = 0.529, p = 0.668), respectively. The SS (r = -0.719, p = 0.000) and TTP (r = 0.538, p = 0.012) of the SI-T curve was correlated to the severity of CP, respectively. DCE MRI has a potential to diagnose moderate to advanced CP. The SS and TTP of the SI-T curve were correlated to the severity of CP.

MRI and MRCP findings of the pancreas in patients with diabetes mellitus: compared analysis with pancreatic exocrine function determined by fecal elastase 1

GOALS

To review magnetic resonance imaging and magnetic resonance cholangiopancreatography (MRCP) findings in patients with diabetes mellitus (DM), with pancreatic exocrine insufficiency, and with combined pancreatic exocrine insufficiency and DM.

STUDY

MRI/MRCP findings of 82 consecutive patients with DM (n=28), pancreatic exocrine insufficiency (n=25), and combination of both (n=29) were evaluated and compared with MRI/MRCP findings of 21 healthy volunteers with normal pancreatic exocrine function. Pancreatic exocrine function was determined by fecal elastase 1. MRCP images were evaluated according to the Cambridge classification. MRI of the pancreas was assessed for pancreatic size, signal intensity ratio (SIR), and arterial/venous enhancement ratio (A/V).

RESULTS

On MRI, significant difference was present in terms of mean values of pancreatic size (P<0.0001), A/V (P<0.02), and SIR (P<0.005) between the control group and groups of patients with DM, pancreatic exocrine insufficiency, and combined DM and pancreatic exocrine insufficiency. No significant difference was observed between groups of patients with DM and pancreatic exocrine function alone in terms of pancreatic size, A/V, and SIR. Chronic pancreatitis MRCP findings were present with increasing frequency in groups of DM, pancreatic exocrine insufficiency, and combination of both.

CONCLUSIONS

MRI/MRCP findings suggesting chronic pancreatitis may exist in patients with DM comparable to patients with pancreatic exocrine insufficiency. The frequency and severity of MRI/MRCP findings increase when the patients have combined DM and pancreatic exocrine insufficiency.

Contrast-enhanced timing robust acquisition order with a preparation of the longitudinal signal component (CENTRA plus) for 3D contrast-enhanced abdominal imaging

PURPOSE

To investigate a new image acquisition method that enables an accurate hepatic arterial phase definition and the visualization of contrast agent uptake processes in abdominal organs like liver, spleen, and pancreas.

MATERIALS AND METHODS

A 3D turbo gradient echo method where a fat suppression prepulse is followed by the acquisition of several profiles was combined with an elliptical centric k-space ordering technique and 3D dynamic elliptical centric keyhole. The new k-space ordering method (CENTRA+) was validated experimentally. In an initial clinical evaluation phase the method was employed in five patients to assess the accuracy of the hepatic arterial phase definition and the visualization of the contrast uptake processes in dynamic scanning in abdominal organs like liver, spleen, and pancreas.

RESULTS

In total, five patients were evaluated using the new k-space order. Our initial results indicate that the new k-space order allows consistent capture of the hepatic arterial phase. In dynamic scanning the extreme short temporal resolution obtained with 3D elliptical centric keyhole enables contrast enhancement to be followed in organs with fast contrast uptake characteristics.

CONCLUSION

The elliptical centric nature of the new image acquisition method effectively allows capture of the contrast enhancement processes with good fat suppression.

Normal pancreatic exocrine function does not exclude MRI/MRCP chronic pancreatitis findings

OBJECTIVE

Abnormal pancreatic function tests have been reported to precede the imaging findings of chronic pancreatitis. Magnetic resonance imaging (MRI) with magnetic resonance cholangiopancreatography (MRCP) is increasingly accepted as the primary imaging modality for the detection of structural changes of early mild chronic pancreatitis. The aim of this study was to evaluate MRI/MRCP findings in patients with symptoms consistent with chronic pancreatitis who have normal Secretin Endoscopic Pancreatic Function test.

METHODS

A retrospective study of 32 patients referred for evaluation of chronic abdominal pain consistent with chronic pancreatitis and reported normal standard abdominal imaging (ultrasound, computed tomography, or MRI). All patients underwent Secretin Endoscopic Pancreatic Function testing and pancreatic MRI/MRCP at our institution. We reviewed the MRI/MRCP images in patients who had normal Secretin Endoscopic Pancreatic Function testing. MRI/MRCP images were assessed for pancreatic duct morphology, gland size, parenchymal signal and morphology, and arterial contrast enhancement.

RESULTS

Of the 32 patients, 23 had normal Secretin Endoscopic Pancreatic Function testing, and 8 of them had mild to marked spectrum of abnormal MRI/MRCP findings that were predominantly focal. Frequencies of the findings were as follows: pancreatic duct stricture (n=3), pancreatic duct dilatation (n=3), side branch ectasia (n=4), atrophy (n=5), decreased arterial enhancement (n=5), decreased parenchymal signal (n=1), and cavity formation (n=1). The remaining15 patients had normal pancreatic structure on MRI/MRCP.

CONCLUSIONS

Normal pancreatic function testing cannot exclude abnormal MRI/MRCP especially focal findings of chronic pancreatitis. Further studies needed to verify significance of these findings and establish MRI/MRCP imaging criteria for the diagnosis of chronic pancreatitis.

Suspected chronic pancreatitis with normal MRCP: findings on MRI in correlation with secretin MRCP

PURPOSE

To review pancreatic MRI findings and their relationship with estimated pancreatic exocrine function on secretin-stimulated MR cholangiopancreatography (S-MRCP) in patients with clinically suspected chronic pancreatitis and normal baseline MRCP findings.

MATERIALS AND METHODS

MRI findings of 26 patients with normal pancreatic duct diameter and without side branch ectasia on MRCP were evaluated. A single radiologist assessed pancreatic size, pancreatic signal intensity ratio (SIR), and arterial enhancement ratio (A/V) at head, body, and tail of the pancreas on T(1)-weighted fat-suppressed and serial contrast-enhanced images at a single session. Combined findings were graded with a composite score. Serial S-MRCP was performed at the same session with standard MRI. Correlation and differences between MRI findings and associated grade of duodenal filling (DF) or the degree of pancreatic duct caliber change (PDC) were analyzed.

RESULTS

Seven patients revealed normal and 19 patients abnormal MRI findings. Significant correlation was present between the degree of DF and mean values of pancreatic size (r = 0.748), SIR (r = 0.610), A/V (r = 0.466), composite score (r = 0.833), and PDC (r = 0.554) separately. PDC correlated with SIR (r = 0.413) and composite score (r = 0.452), but not with A/V or pancreatic size. Significant differences were present between normal and abnormal DF grades in terms of mean values of associated findings of size (P = 0.001), SIR (P = 0.008), A/V (P = 0.019), and PDC (P = 0.001).

CONCLUSION

Patients with clinically suspected chronic pancreatitis and normal MRCP findings may have a spectrum of MRI findings that correlate with the estimated pancreatic exocrine insufficiency on S-MRCP with the increasing number of combined findings.

Magnetic resonance imaging and magnetic resonance cholangiopancreatography findings compared with fecal elastase 1 measurement for the diagnosis of chronic pancreatitis

OBJECTIVES

To correlate magnetic resonance cholangiopancreatography (MRCP) and magnetic resonance imaging (MRI) findings of the pancreas with the pancreatic exocrine function determined by fecal elastase 1 concentration.

METHODS

Magnetic resonance imaging and MRCP findings of 81 consecutive patients with clinically suspected chronic pancreatitis and 21 healthy volunteers were evaluated. All subjects underwent MRI/MRCP and fecal elastase 1 testing within 1 to 4 weeks' interval. Magnetic resonance cholangiopancreatography images were evaluated according to Cambridge classification. Magnetic resonance imaging of the pancreas was assessed for pancreatic size, signal, and arterial enhancement.

RESULTS

All volunteers had normal fecal elastase 1 levels (>200 microg/g) and normal MRI/MRCP findings. Thirty-one of 56 patients revealed MRI and/or MRCP findings despite normal fecal elastase 1 concentration. Four of 25 patients revealed normal MRI and MRCP findings despite low fecal elastase 1 concentration (<200 microg/g). Magnetic resonance imaging findings of size (P = 0.00001), arterial enhancement (P = 0.00001), and parenchymal signal (P = 0.001) were significantly different among the control group, patients with normal fecal elastase 1 levels, and patients with low fecal elastase 1 levels. Magnetic resonance cholangiopancreatography findings (P = 0.00001), pancreatic size (P = 0.00001), arterial enhancement (P = 0.014), and parenchymal signal (P = 0.004) on MRI correlated with the fecal elastase 1 concentration.

CONCLUSIONS

Magnetic resonance imaging/MRCP findings correlate with fecal elastase 1 concentration and may precede pancreatic exocrine insufficiency in the early stages of chronic pancreatitis.

Technology insight: applications of MRI for the evaluation of benign disease of the pancreas

This article reviews the role of MRI in the evaluation of benign pancreatic disease. Although MRI and magnetic resonance cholangiopancreatography (MRCP) are most often used to evaluate the liver and bile duct, technical advances such as the use of secretin stimulation also allow for high-quality imaging of the pancreas and pancreatic ductal system. Secretin-stimulated MRCP (S-MRCP) can aid the diagnosis of acute and chronic pancreatitis, and delineate ductal pathology such as benign strictures and duct leaks. There seems to be a role for S-MRCP in the assessment of pancreatic function and (possibly) sphincter of Oddi dysfunction. When endoscopic or surgical therapy is planned, S-MRCP can help to establish a diagnosis as well as offer a 'road map' to guide therapy. S-MRCP is noninvasive and almost entirely without risk to the patient, which gives it a distinct advantage over traditional endoscopic methods of diagnosis for conditions such as pancreas divisum and other ductal pathology. The information provided by S-MRCP, obtained before endoscopic or surgical therapy is attempted, can assist the patient and physician in making a fully informed decision with regard to the risks and probable benefits of any planned intervention.

Effectiveness of MR imaging for diagnosing the mild forms of acute pancreatitis: comparison with MDCT

PURPOSE

To assess the usefulness of MRI and determine which MR sequence is most effective for diagnosing the mild forms of acute pancreatitis.

MATERIALS AND METHODS

Forty subjects (20 normal volunteers and 20 patients with a mild form of acute pancreatitis) underwent MRI with fat-suppressed T1-weighted fast low-angle shot (FLASH), half-Fourier acquisition single-shot turbo spin-echo (HASTE), and TSE short TI inversion recovery (TSE-STIR) sequences. The 20 patients with a mild form of acute pancreatitis underwent multidetector CT (MDCT) and MRI within a 24-hour interval. We qualitatively analyzed all of the images by assessing inflammatory changes in the pancreas and peripancreatic fat. We quantitatively compared differences in pancreas-liver contrast between the control and patient groups for each MR sequence by measuring the signal intensities of the pancreas and liver.

RESULTS

TSE-STIR was the best of the four modalities for delineating peripancreatic and pancreatic inflammation (P < 0.01). TSE-STIR depicted definitive peripancreatic and pancreatic inflammation in 18 and 15 patients, respectively. MDCT depicted only three cases of peripancreatic inflammation. TSE-STIR was also produced the best the best quantitative results of the MR sequences (P = 0.09).

CONCLUSION

MRI is helpful for diagnosing the mild forms of acute pancreatitis. We recommend the use of TSE-STIR imaging as part of the routine protocol for evaluating pancreatitis.

The M-ANNHEIM classification of chronic pancreatitis: introduction of a unifying classification system based on a review of previous classifications of the disease

BACKGROUND

Several classification systems of chronic pancreatitis have been proposed to provide a basis for treatment and research. All of these previous classifications were designed at the height of pancreatic research of their respective times; thus, each represented the most current knowledge available to pancreatologists at the time. However, none of these classifications provide simultaneously a simple standardized system for the clinical classification of chronic pancreatitis according to etiology, clinical stage, and severity of the disease, nor are they consistently useful for directing clinical practice and comparing interinstitutional data. Thus, we aimed to develop a new classification system of chronic pancreatitis to provide a framework for studying the interaction of various risk factors on the course of the disease.

METHODS

We reviewed the literature on the clinical course of all different forms of chronic pancreatitis, and we reviewed all previous classification systems of the disease. This approach provided a basis for the development of a new and unifying classification of chronic pancreatitis.

RESULTS

We established the M-ANNHEIM multiple risk factor classification system based on the current knowledge of acute and chronic pancreatitis. This classification allows patients to be categorized according to the etiology, clinical stage, and severity of their disease. The severity of pancreatic inflammation was assessed using a scoring system that takes into account the clinical symptoms and treatment options of chronic pancreatitis. Finally, four hypothetical patients were categorized according to the M-ANNHEIM classification system to provide examples of its applicability in clinical practice.

CONCLUSIONS

The M-ANNHEIM multiple risk factor classification system is simple, objective, accurate, and relatively noninvasive, and it incorporates etiology, different stages of the disease, and various degrees of clinical severity. This new classification system will be helpful for investigating the impact and interaction of various risk factors on the course of the disease and will facilitate the comparison and combination of interinstitutional data.

Diagnosis of early-stage chronic pancreatitis by secretin-enhanced magnetic resonance cholangiopancreatography

A diagnostic means of detecting chronic pancreatitis at an early stage, when the disease is still reversible, needs to be developed. Magnetic resonance cholangiopancreatography (MRCP) has recently been evolving as an important tool for the evaluation of chronic pancreatitis. In patients with moderate chronic pancreatitis, the pancreatic parenchyma displays an abnormal enhancement pattern on T1-weighted sequences after gadolinium administration. The presence of a signal intensity ratio of <1.7 in the arterial phase and/or delayed peak enhancement after contrast administration has a sensitivity of 92% and a specificity of 75% for the demonstration of early chronic pancreatitis. The secretin-induced pancreatic T2 signal intensity changes are significantly reduced in patients with a mild exocrine pancreatic insufficiency as compared with healthy volunteers. MRCP visualizes fluid in the pancreatic and biliary ducts as high signal intensity on heavily T2-weighted sequences. However, visualization of normal or minimally dilated pancreatic ducts by MRCP is more challenging because of their small size. Secretin administration stimulates fluid and bicarbonate secretion by the exocrine pancreas; consequently, it improves the pancreatic duct and side-branch delineation and allows an evaluation of the exocrine pancreatic function. Side-branch ectasia, mild ductal dilatation with loss of the normal gentle taper, and mural irregularities are the pathognomonic MRCP features of early-stage chronic pancreatitis. Through measurement of the duodenal filling, secretin-MRCP allows quantitative assessment of the exocrine pancreatic function, even in patients with a mild exocrine insufficiency. The morphology of the pancreatic ducts, particularly in the early stages, does not always correlate with the functional status. MRCP permits visualization of the ductal changes and furnishes functional information on the pancreas; this combination may enhance its diagnostic accuracy so that MRCP can become a valuable diagnostic means in early-stage chronic pancreatitis.

Serial contrast-enhanced MRI of the pancreas: correlation with secretin-stimulated endoscopic pancreatic function test

RATIONALE AND OBJECTIVES

The purpose of this study was to determine the relationship between the pancreatic enhancement on serial contrast-enhanced MRI (CEMRI) and pancreatic exocrine function using the secretin-stimulated endoscopic pancreatic function test (ePFT).

MATERIALS AND METHODS

A total of 30 patients with clinical symptoms consistent with chronic pancreatitis underwent CEMRI of the abdomen and ePFT within a 1- to 4-week interval. CEMRI was performed in arterial, early venous, and late venous phases. Secretin ePFT was performed with the measurement of HCO(3) concentration from the duodenal aspirates after secretin stimulation. Contrast enhancement ratio of the arterial phase to early venous phase was measured on CEMRI (SIRa/SIRv). A three-point evaluation system was used for grading the HCO(3) concentration and the enhancement ratio on MRI. For the significance of correlation, kappa statistics was used. Sensitivity and specificity of CEMRI was determined for the diagnosis of early chronic pancreatitis accepting ePFT as a reference.

RESULTS

Twenty patients had identical scores on both secretin ePFT and CEMRI. Ten patients revealed discrepancy in scores. Kappa statistics revealed moderate agreement between MRI and ePFT (kappa = 0.44). Sensitivity and specificity values for the diagnosis of pancreatitis were 82% and 57%, respectively. Positive predictive value was 56%, and negative predictive value was 86%.

CONCLUSION

The results of our data indicate that serial CEMRI is an appropriate imaging technique to rule out early chronic pancreatitis. However, secretin-stimulated imaging or ePFT may still be needed for the definite diagnosis of pancreatic exocrine dysfunction.

Magnetic resonance imaging in the detection of pancreatitis and pancreatic neoplasms

This article presents current magnetic resonance imaging techniques for the diagnosis of acute and chronic pancreatitis and pancreatic neoplasms. It emphasises the need for a comprehensive protocol combining imaging sequences of the pancreatic parenchyma with magnetic resonance angiography and secretin-enhanced magnetic resonance cholangiopancreatography in order to evaluate the full range of pancreatic inflammatory and neoplastic conditions. Imaging characteristics that may indicate a specific diagnosis are discussed.

Pancreas duct abnormalities in patients with ulcerative colitis: a magnetic resonance pancreatography study

BACKGROUND

The presumed etiology and prevalence of pancreatic abnormalities in patients with ulcerative colitis (UC) have been controversial. We conducted a controlled (cross-sectional) study of patients with UC compared with non-UC controls to determine the prevalence of pancreatic duct abnormalities in patients with UC and to determine if these are specific to UC using magnetic resonance cholangiopancreatography.

METHODS

Magnetic resonance cholangiopancreatography was performed on 79 unselected patients with UC and 45 non-UC controls, without a history of pancreatitis attack, between February 2000 and May 2003.

RESULTS

Among patients with UC, the prevalence of pancreatic duct abnormalities was 16.4% (95% confidence interval, 8.3%-24.6%): coexisting dilatation and narrowing of the main pancreatic duct were found in 5; diffuse narrowing of pancreatic ducts in 5; and dilatation of pancreatic ductal branches in 3. These abnormalities were compatible with chronic pancreatitis. Among the controls, no pancreatic duct abnormality was found.

CONCLUSIONS

Changes in the pancreatic duct were found in approximately one-sixth of patients with UC, none of whom had a history of overt pancreatitis. These pancreatic duct abnormalities are likely to be specific to patients with UC.

Magnetic Resonance Imaging of the Pancreas: The Future Is Now

MR imaging has made significant advances in recent years, with an increasingly important role in the detection, characterization, and staging of pancreatic diseases. MRI is appealing as a noninvasive imaging modality as it can evaluate the pancreas, the vasculature, and the pancreaticobiliary ducts in a single examination. Advantages of MRI include its excellent soft tissue contrast resolution and anatomic detail and absence of ionizing radiation. This article reviews the utility of MRI and its use not only as a problem-solving tool but its potential use as a primary examination (similar to CT) in a wide variety of pancreatic diseases.

Pancréatites chroniques et inflammatoires : apport des techniques d’imagerie en coupe

The role of diagnostic imaging in chronic and inflammatory pancreatitis is to detect structural changes of the ducts and pancreatic parenchyma, to assess the functional integrity of the gland, to detect associated complications, and to assist in management. These goals may be achieved using helical CT and MR imaging with secretin stimulation. In this review, the advantages of each technique are discussed and illustrated.

Dynamic contrast-enhanced MRI of the pancreas: initial results in healthy volunteers and patients with chronic pancreatitis

PURPOSE

To characterize pancreatic perfusion in volunteers and patients with chronic pancreatitis (CP) by dynamic contrast-enhanced (DCE) MRI.

MATERIALS AND METHODS

Pancreatic enhancement after bolus injection of Gd-DTPA with a three-dimensional ultrafast partial-Fourier radiofrequency (RF) spoiled gradient-echo (GE) acquisition was examined prospectively. An acquisition volume of the pancreatic parenchyma was obtained every 4.2 seconds during a single breath-hold in 31 volunteers and 19 patients with CP. We calculated the wash-in rate and a newly defined parameter, the "time-to-inflow deceleration" (TID). A statistical analysis of the differences between both groups was performed with the use of Student's t-test.

RESULTS

Significant differences in the TID and wash-in rate were found for the head and body of the pancreas: the TID was 22.4 sec +/- 4.4 sec and 23.5 sec +/- 6.1 sec in the pancreatic head and body of the healthy volunteers, and 29.8 sec +/- 8.6 sec and 29.4 sec +/- 3.8 sec in patients with CP. The wash-in rate was 96 +/- 37 sec(-1) and 101 +/- 27 sec(-1) in controls, and 62 +/- 17 sec(-1) and 75 +/- 27 sec(-1) in CP.

CONCLUSION

CP can be identified by semiquantitative changes on DCE-MRI. Whether DCE-MRI of the pancreas can be used to detect early CP remains to be validated.

Contrast-enhanced computed tomography in acute pancreatitis: does contrast medium worsen its course due to impaired microcirculation?

BACKGROUND

An early and accurate diagnosis of severe acute (necrotizing) pancreatitis is important to allow timely institution of therapy to limit the extra-pancreatic sequelae of this necrotizing process and to minimize the incidence of super-infection of the necrosis (i.e., progression to infected necrosis). Contrast-enhanced computed tomography (CECT) has become the cornerstone of diagnosis by confirming the clinical diagnosis of severe acute pancreatitis based on the various clinical scoring criteria. Moreover, CECT serves as an anatomic roadmap for guiding radiological and surgical interventions. However, still-controversial experimental studies in animals in the mid-1990s suggested that the use of intravenous radiographic contrast media early in the course of the disease might exacerbate the necrotizing process by further impairing the already compromised pancreatic microcirculation. A series of experimental and clinical studies followed that have both refuted and supported this claim; unfortunately, none is conclusive, and the topic remains, as yet, unresolved.

AIMS

Our objective was to review objectively the available literature found by a Medline search on this subject.

METHODS

Meta-analysis and review.

RESULTS AND CONCLUSION

Our conclusion, after analysis of these studies, is that there are no well-substantiated data that could resolve the controversy. However, several caveats will be offered.