Comparison of MR and CT scanning in severe acute pancreatitis: initial experiences

Mannose-coated gadolinium liposomes for improved magnetic resonance imaging in acute pancreatitis

Background

Acute pancreatitis (AP) is an acute inflammatory condition of the pancreas. The symptoms, treatment, and prognosis of mild and severe AP are different, and severe AP is a potentially life-threatening disease with a high incidence of complications and high mortality rate. Thus, it is urgent to develop an effective approach to reliably discriminate between mild and severe AP.

Methods

We have developed novel gadolinium-diethylenetriaminepentaacetic (Gd-DTPA)-loaded mannosylated liposomes (named thereafter M-Gd-NL) that preferably target macrophages in AP. The targeting ability of M-Gd-NL toward macrophages in AP and its ability to discriminate between mild and severe AP were evaluated.

Results

The liposomes were of desired particle size (~100 nm), Gd-DTPA encapsulation efficiency (~85%), and stability. M-Gd-NL and non-targeted Gd-DTPA-loaded liposomes (Gd-NL) exhibited increased relaxivity compared with Gd-DTPA. Compared with Gd-NL and Gd-DTPA, M-Gd-NL showed increased uptake in macrophages, resulting in increased T₁ imaging ability both in vitro (macrophage cell line) and in vivo (severe AP model). Importantly, M-Gd-NL had the ability to discriminate between mild and severe AP, as reflected by a significantly higher T₁ magnetic resonance imaging signal in severe AP than in mild AP. M-Gd-NL did not show severe organ toxicity in rats.

Conclusion

Our data suggest that M-Gd-NL had enhanced magnetic resonance imaging ability by targeting macrophages in AP and good ability to discriminate between mild and severe AP. We believe that M-Gd-NL could shed new light on the diagnosis of AP in the near future.

Diffusion-weighted magnetic resonance imaging indicates the severity of acute pancreatitis

PURPOSE

To test the use of diffusion-weighted magnetic resonance imaging (DW-MRI) to differentiate between different degrees of severity of acute pancreatitis (AP).

METHOD

Thirty-six patients who underwent DW-MRI and magnetic resonance cholangiopancreatography were divided into patients with mild AP (mAP, n = 15), patients with necrotizing AP (nAP, n = 8), and patients with a normal pancreas (nP, n = 15; controls). The pancreas was divided into head, body, and tail, and each segment was classified according to image features: pattern 1, normal; pattern 2, mild inflammation; and pattern 3, necrosis. Apparent diffusion coefficients (ADCs) were measured in each segment and correlated with clinical diagnoses.

RESULTS

A total of 108 segments was assessed (three segments per patient). Segments classified as pattern 1 in the nP and mAP groups showed similar ADC values (P = 0.29). ADC values calculated for the pancreatic segments grouped according to the different image patterns (1-3) were significantly different (P < 0.001). Comparisons revealed significant differences in signal intensity between all three patterns (P < 0.05).

CONCLUSIONS

DW-MRI was a compatible and safe image option to differentiate tissue image patterns in patients with mAP, nAP, and nP, mainly in those with contraindications to contrast-enhanced MRI (which is classically required for determining the presence of necrosis) or computed tomography. ADC measures allowed precise differentiation between patterns 1, 2, and 3.

Nontraumatic abdominal pain in pregnancy: imaging considerations for a multiorgan system problem

Nontraumatic abdominal pain in the pregnant patient can present a clinician with a variety of diagnostic possibilities. The overlap between signs and symptoms expected in normal pregnancy and these many pathologic possibilities does little to help focus the clinician's diagnostic efforts. Fear of ionizing radiation's effects on the fetus has driven efforts to refine medical imaging algorithms in such a way as to attempt to eliminate its use at all cost. In today's world, we are nearly there. In this review the differential diagnosis of nontraumatic abdominal pain in the pregnant patient will be explored. Of note is the recurring theme that much of what can be done today with regard to diagnostic imaging, both in general and with regard to this specific subset of patients, centers on the use of the non-ionizing modalities of ultrasound and magnetic resonance imaging.

Diffusion MRI of acute pancreatitis and comparison with normal individuals using ADC values

The aim of this study was to retrospectively measure and compare pancreatic apparent diffusion coefficient (ADC) in patients with acute pancreatitis (AP) with aged matched controls who underwent diffusion weighted imaging (DWI). The institutional review board approved this retrospective Health Insurance Portability and Accountability Act compliant study with a waiver for informed consent. Pancreatic ADC values from 27 patients with a clinical diagnosis of AP and 38 normal age-matched controls evaluated with DWI (b = 0 and 800 mm(2)/s) were retrospectively and independently measured by two radiologists. The ADCs were compared between the groups and between each of the pancreatic segments in the normal group. Inter-observer reliability was calculated and receiver operating characteristic analysis was used to determine the sensitivity and specificity of DW imaging in the diagnosis of acute pancreatitis. P < 0.05 was considered statistically significant. The ICC for inter-observer reliability was 0.98 in the control and 0.97 in the AP group. The mean pancreatic ADC in the AP group (1.32 × 10(-3) mm(2)/s ± 0.13) was significantly lower than in the normal group (1.77 × 10(-3) mm(2)/s ± 0.32). There was no significant difference in mean ADCs between each of the pancreatic segments in the controls. A threshold ADC value of 1.62 × 10-3 mm(2)/s yielded a sensitivity of 93% and specificity of 87% for detecting acute pancreatitis for b values of 0 and 800 s/mm(2). Pancreatic ADCs are significantly lower in patients with AP than normal controls.

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.

New diagnostic criteria of acute pancreatitis

Practical guidelines for the diagnosis of acute pancreatitis are presented so that a rapid and adequate diagnosis can be made. When acute pancreatitis is suspected in patients with acute onset of abdominal pain and tenderness mainly in the upper abdomen, the diagnosis of acute pancreatitis is made on the basis of elevated levels of pancreatic enzymes in the blood and/or urine. Furthermore, other acute abdominal diseases are ruled out if local findings associated with pancreatitis are confirmed by diagnostic imaging. According to the diagnostic criteria established in Japan, patients who present with two of the following three manifestations are diagnosed as having acute pancreatitis: characteristic upper abdominal pain, elevated levels of pancreatic enzymes, and findings of ultrasonography (US), CT or MRI suggesting acute pancreatitis. Detection of elevated levels of blood pancreatic enzymes is crucial in the diagnosis of acute pancreatitis. Measurement of blood lipase is recommended, because it is reported to be superior to all other pancreatic enzymes in terms of sensitivity and specificity. For measurements of the blood amylase level widely used in Japan, it should be cautioned that, because of its low specificity, abnormal high values are also often obtained in diseases other than pancreatitis. The cut-off level of blood pancreatic enzymes for the diagnosis of acute pancreatitis is not able to be set because of lack of sufficient evidence and consensus to date. CT study is the most appropriate procedure to confirm image findings of acute pancreatitis. Elucidation of the etiology of acute pancreatitis should be continued after a diagnosis of acute pancreatitis. In the process of the etiologic elucidation of acute pancreatitis, judgment whether it is gallstone-induced or not is most urgent and crucial for deciding treatment policy including the assessment of whether endoscopic papillary treatment should be conducted or not. The diagnosis of gallstone-induced acute pancreatitis can be made by combining detection of elevated levels of bilirubin, transamylase (ALT, AST) and ALP detected by hematological examination and the visualization of gallstones by US.

Magnetic resonance imaging in pancreatitis

Pancreatitis can occur in acute and chronic forms. Magnetic resonance imaging (MRI) plays an important role in the early diagnosis of both conditions and complications that may arise from acute or chronic inflammation of the gland. Standard MRI techniques including T1-weighted and T2-weighted fat-suppressed imaging sequences together with contrast-enhanced imaging can both aid in the diagnosis of acute pancreatitis and demonstrate complications as pseudocysts, hemorrhage, and necrosis. Combined use of MRI and MR cholangiopancreatography can show both parenchymal findings that are associated with chronic pancreatitis including pancreatic size and signal and arterial enhancements, all of which are diminished in chronic pancreatitis. The degree of main pancreatic duct dilatation and/or the number of side branch ectasia determines the diagnosis of chronic pancreatitis and its severity. In this paper, we report the spectrum of imaging findings of acute and chronic pancreatitis on MRI and MR cholangiopancreatography.

Imaging assessment of acute pancreatitis: a review

Acute pancreatitis is one of the more commonly encountered etiologies in the emergency setting. While in the majority of cases it is a self-limiting disease which responds rapidly to conservative management, in some cases acute pancreatitis may present with a more pronounced, sometimes dramatic, clinical picture and requires immediate medical care to avoid fatal complication. In this context, imaging plays a significant role because it enables identification of the development of the disease and local/systemic complications. The purpose of this article is to offer an overview of the disease and a spectrum of imaging findings in patients with acute pancreatitis, emphasizing the role of ultrasound, computed tomography, and magnetic resonance imaging according to the appropriate clinical context and advantages and limitations of each imaging modality are examined.

Prospective evaluation of nonenhanced MR imaging in acute pancreatitis

PURPOSE

To compare the value of nonenhanced (NE) magnetic resonance imaging (MRI) (NE-MRI) with contrast-enhanced (CE) computed tomography (CT) (CE-CT) scan in assessing acute pancreatitis (AP) and in evaluating the severity index (SI) with clinical outcome.

MATERIALS AND METHODS

Patients with AP were prospectively investigated by CE-CT scan and NE-MRI on admission. MRI was performed with fat-saturated T1-weighted imaging, T2-weighted imaging, and MR cholangiopancreatography (MRCP). Balthazar's grading system was used to evaluate the NE-MRI severity index (CTSI, MRISI) and it was compared to the clinical outcome.

RESULTS

A total of 90 patients (median age = 55 years) were included in the study. AP was of biliary etiology in 37 patients (41%). On admission, AP was assessed as grade III by CTSI in four patients (4%), whereas 19 patients were classified grade III by MRISI. The coefficient correlation between CTSI and MRISI was good, with r = 0.6 (P < 0.001). Considering CE-CT scan as the gold standard, sensitivity (Sn), specificity (Sp), positive predictive value (PPV), and negative predictive value (NPV) of NE-MRI for detecting severe AP based on imaging criteria were 100%, 82.6%, 100%, and 21%, respectively. NE-MRI discriminates normal pancreatic parenchyma from edema and necrosis with a correlation between morbidity (P < 0.008).

CONCLUSION

NE-MRI seems to be a reliable method of staging AP severity in comparison to CE-CT scan.

Staging of severity and prognosis of acute pancreatitis by computed tomography and magnetic resonance imaging-a comparative study

BACKGROUND

Determination of severity of acute pancreatitis is important to determine prognosis.

AIMS

(1) the staging of acute pancreatitis by computed tomography and magnetic resonance imaging, (2) the correlation of computed tomography and magnetic resonance severity indices and 3) the correlation of magnetic resonance severity index with C-reactive protein, Ranson score, duration of hospitalization and clinical outcome.

PATIENTS

Thirty-five patients (median age: 64 (27-89)) were studied. Twenty-two patients had biliary acute pancreatitis.

METHODS

The following examinations were conducted: (1) computed tomography 48 h, 7 and 30 days after admission, (2) magnetic resonance imaging 7 and 30 days after admission, (3) C-reactive protein and 4) Ranson score. Clinical outcome was determined on a scale 0-3 (0: remission, 1: local complications, 2: systemic complications, 3: death).

RESULTS

Six of 35 patients (17%) had necrotizing acute pancreatitis. Fifteen of 35 patients (43%) had severe acute pancreatitis according to Ranson criteria. A significant correlation was noted between magnetic resonance severity index and C-reactive protein (r=0.419, p<0.005), Ranson score (r=0.431, p<0.05), duration of hospitalization (r=0.497, p<0.01) and clinical outcome (r=0.420, p<0.05). Comparison of the imaging methods showed a significant correlation between magnetic resonance severity index and computed tomography severity index (r=0.887, p<0.01).

CONCLUSION

Magnetic resonance imaging is of comparable diagnostic and prognostic value with computed tomography in the staging of acute pancreatitis.

Cross-Sectional Imaging in Acute Pancreatitis

Acute pancreatitis is a common disease with potentially serious outcomes. Multiple imaging modalities can be used to evaluate the disease process and its associated complications. Familiarity with the pathogenesis of this disease, indications for imaging, imaging protocols, staging systems, and the strengths and weaknesses of various modalities will help the radiologist optimize patient care.

JPN Guidelines for the management of acute pancreatitis: diagnostic criteria for acute pancreatitis

The currently used diagnostic criteria for acute pancreatitis in Japan are presentation with at least two of the following three manifestations: (1) acute abdominal pain and tenderness in the upper abdomen; (2) elevated levels of pancreatic enzyme in the blood, urine, or ascitic fluid; and (3) abnormal imaging findings in the pancreas associated with acute pancreatitis. When a diagnosis is made on this basis, other pancreatic diseases and acute abdomen can be ruled out. The purpose of this article is to review the conventional criteria and, in particular, the various methods of diagnosis based on pancreatic enzyme values, with the aim of improving the quality of diagnosis of acute pancreatitis and formulating common internationally agreed criteria. The review considers the following recommendations:

— Better even than the total blood amylase level, the blood lipase level is the best pancreatic enzyme for the diagnosis of acute pancreatitis and its differentiation from other diseases.

— A pivotal factor in the diagnosis of acute pancreatitis is identifying an increase in pancreatic enzymes in the blood.

— Ultrasonography (US) is also one of the procedures that should be performed in all patients with suspected acute pancreatitis.

— Magnetic resonance imaging (MRI) is one of the most important imaging procedures for diagnosing acute pancreatitis and its intraperitoneal complications.

— Computed tomography (CT) is also one of the most important imaging procedures for diagnosing acute pancreatitis and its intraabdominal complications. CT should be performed when a diagnosis of acute pancreatitis cannot be established on the basis of the clinical findings, results of blood and urine tests, or US, or when the etiology of the pancreatitis is unknown.

— When acute pancreatitis is suspected, chest and abdominal X-ray examinations should be performed to determine whether any abnormal findings caused by acute pancreatitis are present.

— Because the etiology of acute pancreatitis can have a crucial influence on both the treatment policy and severity assessment, it should be evaluated promptly and accurately. It is particularly important to differentiate between gallstone-induced acute pancreatitis, which requires treatment of the biliary system, and alcohol-induced acute pancreatitis, which requires a different form of treatment.

Magnetic resonance evaluation of pregnant patients with acute abdominal pain

Acute abdominal pain in a pregnant patient is associated with a long differential diagnosis, and diagnostic imaging is often required to guide management. Ultrasound is safe and widely available; however, maternal structures may be difficult to evaluate during pregnancy due to anatomic changes. Computed tomography is accurate but exposes the fetus to ionizing radiation. Magnetic resonance (MR) imaging provides excellent anatomic resolution and tissue characterization without ionizing radiation, and MR diagnosis frequently requires no contrast administration. Using an appropriate combination of sequences, MR imaging can reliably demonstrate many causes of acute abdominal pain during pregnancy.

MR imaging of the pancreas

MR imaging is a valuable tool in the assessment of the full spectrum of pancreatic diseases. MR imaging techniques are sensitive for the evaluation of pancreatic disorders in the following settings: (1) TI-weighted fat-suppressed and dynamic gadolinium-enhanced SGE imaging for the detection of chronic pancreatitis, ductal adeno-carcinoma, and islet-cell tumors; (2) T2-weighted fat-suppressed imaging and T2-weighted breath-hold imaging for the detection of islet-cell tumors;and (3) precontrast breath-hold SGE imaging for the detection of acute pancreatitis. Relatively specific morphologic and signal intensity features permit characterization of acute pancreatitis,chronic pancreatitis, ductal adenocarcinoma, insulinoma, gastrinoma, glucagonoma, microcystic cystadenoma, macrocystic cystadenoma, and solid and papillary epithelial neoplasm. MR imaging is effective as a problem-solving modality because it distinguishes chronic pancreatitis from normal pancreas and chronic pancreatitis with focal enlargement from pancreatic cancer in the majority of cases.MR imaging studies should be considered in the following settings: (1) in patients with elevated serum creatinine, allergy to iodine contrast, or other contraindications for iodine contrast administration; (2) in patients with prior CT imaging who have focal enlargement of the pancreas with no definable mass; (3) in patients in whom clinical history is worrisome for malignancy and in whom findings on CT imaging are equivocal or difficult to interpret; and (4) in situations requiring distinction between chronic pancreatitis with focal enlargement and pancreatic cancer. Patients with biochemical evidence of islet-cell tumors should be examined by MR imaging as the first-line imaging modality because of the high sensitivity of MR imaging for detecting the presence of islet-cell tumors and determining the presence of metastatic disease.

Computed tomography and magnetic resonance imaging in the assessment of acute pancreatitis

BACKGROUND & AIMS

This study aimed to compare the accuracy of magnetic resonance imaging (MRI) with computed tomography (CT) in assessing acute pancreatitis (AP) and to explore the correlation between MRI findings and clinical outcome.

METHODS

Patients with AP were investigated by contrast-enhanced CT and MRI on admission and 7 and 30 days thereafter. MRI was performed with intravenous secretin and contrast medium. Balthazar's grading system was used to measure CT and MRI severity indices (CTSI and MRSI, respectively).

RESULTS

Thirty-nine patients (median age, 47 years; range, 15-86) were studied. AP was of biliary etiology in 19 patients (49%). On admission, AP was assessed clinically as severe in 7 patients (18%). A strong correlation was demonstrated between CTSI and MRSI on admission and 7 days later. MRSI on admission correlated with the following: the Ranson score, C-reactive protein levels 48 hours after admission, duration of hospitalization, and clinical outcome regarding morbidity, including local and systemic complications. Considering the Ranson score as the gold standard, MRI detected severe AP with 83% (58-96, 95% CI) sensitivity, 91% (68-98) specificity vs. 78% (52-93) and 86% (63-96) for CT. Magnetic resonance cholangiopancreatography after i.v. secretin injection showed pancreatic duct leakage in 3 patients (8%).

CONCLUSIONS

MRI is a reliable method of staging AP severity, has predictive value for the prognosis of the disease, and has fewer contraindications than CT. It can also detect pancreatic duct disruption, which may occur early in the course of AP.

Management of severe acute pancreatitis

BACKGROUND

Acute pancreatitis is still associated with significant morbidity and mortality. Current management guidelines are sometimes equivocal, particularly in relation to the surgical treatment of severe disease. This review assesses available investigative and treatment strategies to allow the development of a formalized management approach.

METHODS

A literature review of diagnosis, staging and management of acute pancreatitis was performed.

RESULTS AND CONCLUSION

Recent evidence has helped to clarify the roles of computed tomography, endoscopic retrograde cholangiopancreatography, prophylactic antibiotics, enteral feeding and fine-needle aspiration for bacteriology in the management of acute pancreatitis. Despite a relative shortage of prospective randomized trials there has been a significant change in the surgical management of acute pancreatitis over the past 20 years. This change has been away from early aggressive surgical intervention towards more conservative management, except when infected necrosis is confirmed. A formalized approach, with appropriate use of the various non-surgical and surgical options, is feasible in the management of severe acute pancreatitis.

Staging acute pancreatitis: where are we now?

Acute pancreatitis is a potentially lethal disease in about 20% of all the cases. Early identification of those patients with the severe type of the disease is of a great importance as intensive care treatment and other therapeutic manipulations can apply to alter the clinical course, and finally the outcome. Therefore, there is a need for precise criteria for severity prediction--that can be easily applied with high accuracy and sensitivity--very early after the onset of acute pancreatitis. Although no 'ideal' predictor exists so far, APACHE II score, C-reactive protein and the trypsinogen activation peptide, could be used in clinical practice. Other prognostic markers such as interleukin-6 and interleukin-8 could be useful in the near future, as soon as proper assays will be available. Furthermore, the development of logistic models, based on different parameters concerning the severity of the individual patient, is another option for the future.

Visualization of the heterogeneous internal structure of so-called "pancreatic necrosis" by magnetic resonance imaging in acute necrotizing pancreatitis

INTRODUCTION

Contrast-enhanced computed tomography (CT) is the gold standard for assessing the severity of acute pancreatitis, especially for evaluating the presence of pancreatic necrosis (poorly perfused area). However, the contrast medium used for CT is potentially toxic to the pancreas and kidney. Therefore, medical institutions without facilities for hemodialysis hesitate to acquire contrast-enhanced CT images. Diagnostic values of magnetic resonance imaging (MRI) in pancreatic diseases have been shown.

AIM

To evaluate the usefulness of MRI in the assessment of the severity of acute pancreatitis.

RESULTS

All necrotic regions in the pancreas were visualized by gadolinium-enhanced MRI. Furthermore, MRI can discriminate the poorly perfused pancreatic area, namely so-called "pancreatic necrosis" judged on CT, into three parts: 1) necrotic area of the pancreatic parenchyma, 2) perinecrotic fluid collection, and 3) hemorrhagic foci. Inflammatory changes that were required for severity grading were also evaluated sufficiently by MRI.

CONCLUSION

These results suggest that MRI is useful for the assessment of severity of acute pancreatitis.

New laboratory tests in acute pancreatitis

Acute pancreatitis (AP) is a common disease with wide variation of severity. The diagnosis of AP is usually based on high serum amylase or lipase values but the accuracy of these methods is considered unsatisfactory. One in five of the patients develops a severe disease and carries a considerable risk of development of organ failure and high mortality. Early detection of patients with severe AP and especially those with increased risk of organ failure is importance since such patients seem to benefit from treatment in an intensive care unit started as soon as possible after presentation. In addition to enzymological methods, increasing interest has been focused on laboratory markers reflecting the level of inflammatory response in AP. At present, in routine clinical work the most commonly used severity marker is serum C-reactive protein, the concentration of which rises too slowly to be used for early prediction of severity. New therapies aiming at modifying the course of systemic inflammation in AP are being developed and therefore monitoring the patient's immune inflammatory status is needed. In this review article we present the current knowledge of laboratory tests, which has been evaluated for diagnostic and prognostic purposes in AP.

MR imaging of the pancreas

Current MR imaging technology offers the surgeon diagnostic information about pancreatic diseases. This article reviews the basics of MR imaging formation and the rationale for the different types of imaging sequences that comprise a comprehensive pancreaticobiliary examination. Clinical examples include evaluation of pancreatic neoplasms, acute and chronic pancreatitis, and congenital abnormalities.

Assessment of acute abdominal pain in the pregnant patient

The request to image a pregnant patient with abdominal pain often leads to concern and frustration for the referring clinician as well as the radiologist. In this report we will review the basic principles of radiation safety when imaging the pregnant woman, consider the diagnostic possibilities for the causes of abdominopelvic pain, and discuss the available imaging modalities to provide a basis for tailoring an imaging plan to the individual patient.

Acute pancreatitis: interobserver agreement and correlation of CT and MR cholangiopancreatography with outcome

PURPOSE

To assess the correlation between and the interobserver agreement of contrast medium-enhanced computed tomography (CT) and nonenhanced and contrast-enhanced magnetic resonance (MR) imaging findings in patients with acute pancreatitis and to correlate these findings with outcome.

MATERIALS AND METHODS

Two blinded reviewers separately assessed contrast-enhanced CT and nonenhanced and contrast-enhanced MR images in 30 patients with acute pancreatitis and established a severity index based on the presence of peripancreatic fluid collections and pancreatic necrosis. The Spearman rank correlation coefficient and weighted kappa statistic were used to assess the correlation between each imaging technique and the interobserver agreement, respectively. Correlation between hospitalization days, morbidity, and severity indexes were assessed by using linear correlation.

RESULTS

A strong correlation existed for both reviewers when comparing contrast-enhanced CT with nonenhanced (r = 0.82, 0.79) or contrast-enhanced (r = 0.82, 0.79) MR cholangiopancreatography or when comparing nonenhanced and contrast-enhanced MR cholangiopancreatography (r = 0.99, 1.00). The interobserver agreement in staging was stronger with nonenhanced (kappa = 0.76) and contrast-enhanced (kappa = 0.78) MR cholangiopancreatography than with contrast-enhanced CT (kappa = 0.70). There was no linear correlation between the severity index for contrast-enhanced CT and outcome, while there was a linear correlation between nonenhanced or contrast-enhanced MR cholangiopancreatographic staging and the patient morbidity rate.

CONCLUSION

MR cholangiopancreatography could be an alternative to contrast-enhanced CT for the initial staging of acute pancreatitis.

Ileus secondary to pancreatic pseudocyst

Intra-or extrapancreatic pseudocyst is a common local complication in pancreatitis. Pathological involvement of the colon secondary to acute and chronic pancreatitis is a rare complication of major clinical interest. Contiguity with the tail of the pancreas and certain anatomical relationships, particularly at the level of the peritoneal reflections, explain the involvement of, particularly, the left flexure of the colon and the adjacent part of the transverse colon. We report a patient, presenting with ileus resulting from pressure of a giant pseudocyst secondary to acute pancreatitis, to share the diagnostic and chronologic follow-up computed tomography (CT) scanning findings of this rare complication.

The relative safety of MRI contrast agent in acute necrotizing pancreatitis

OBJECTIVE

To validate the safety of gadolinium-diethylenetriamine pentaacetic acid (GD-DTPA) by measuring its effect on pancreatic capillary perfusion and acinar injury in acute pancreatitis.

BACKGROUND

Contrast-enhanced computed tomography (CECT) is proposed as a gold standard for early evaluation of acute necrotizing pancreatitis. However, iodinated contrast media used for CECT have been shown in these circumstances to reduce pancreatic capillary flow and increase necrosis and mortality. Recent reports suggest that post-GD MRI provides images comparable to CECT in the assessment of severe acute pancreatitis.

METHODS

Necrotizing pancreatitis was induced in 14 Wistar rats by intraductal glycodeoxycholic acid (10 mM/L) and intravenous caerulein (5 microg/kg/h) over 6 hours. Intravital microscopic quantitation of pancreatic capillary blood flow was performed using fluorescein isothiocyanate-labeled erythrocytes after induction of pancreatitis and 30 and 60 minutes after an intravenous bolus of either Ringer's solution or GD-DTPA (0.2 mL/kg).

RESULTS

The two study groups were comparable with regard to mean arterial pressure, heart rate, arterial blood gases, hematocrit, amylase, lipase, and trypsinogen activation peptide production throughout the experiment. GD-DTPA did not reduce capillary flow (1.93 +/- 0.05 nL/capillary/min) compared to animals infused with Ringer's solution (1.90 +/- 0.06 nL/capillary/min).

CONCLUSIONS

Intravenous injection of GD-DTPA does not further impair pancreatic microcirculation or increase acinar injury in acute necrotizing pancreatitis. Because of this advantage over CT contrast medium, further development of MRI as a staging tool in acute pancreatitis seems desirable.

Diagnostic standards for acute pancreatitis

An accurate history and thorough physical examination will often raise clinical suspicion of acute pancreatitis in the differential diagnosis of a patient presenting with acute abdominal pain. An accurate diagnosis is needed to eliminate etiologies of acute abdominal pain and to appropriately direct therapy. Confirmation of the diagnosis is most often made by evaluation of serum amylase and lipase levels. Although hyperamylasemia is found in the majority of patients with acute pancreatitis, other nonpancreatic acute abdominal conditions may be present with hyperamylasemia. CT scanning provides an accurate confirmation of clinical and laboratory findings and offers excellent anatomic and morphologic representation of the pancreas and peripancreatic tissue. The following article, written by the late John H.C. Ranson, presents a discussion of the modalities available for diagnosing acute pancreatitis.

T2-weighted and dynamic enhanced MRI in acute pancreatitis: comparison with contrast enhanced CT

The purpose of this study was to compare T2-weighted and dynamic contrast enhanced MRI with contrast enhanced CT in patients with severe acute pancreatitis. Thirty-two patients were examined using axial T2-weighted spin-echo imaging (TR 1801, TE 15/90) and a multi-slice rapid gradient-echo sequence (TR 135, TE 4, FA 80 degrees) (FLASH) in axial and coronal planes. Fifteen 5 mm axial slices at 10 mm intervals were acquired during a single breath-hold of 19 s before, and at 10 and 40 s after a bolus injection of Gd-DTPA. Additional FLASH images in the coronal plane were obtained 2 min after injection of contrast medium. MR was compared with contemporary enhanced CT by two blinded observers who scored pancreatic viability and the content of intra and extra-pancreatic fluid collections. The presence of gas, calcification and haemorrhage was noted. Abnormalities in adjacent organs, evidence of vascular occlusion and indicators of aetiology were also recorded. MR and CT were concordant in distinguishing viable pancreatic tissue from areas of necrosis. MR appeared to be more effective than CT in characterizing the content of fluid collections and in demonstrating gall stones, although CT remains superior in detecting flecks of gas and calcification. MR carries some advantages over CT and can be regarded as an alternative primary technique in patients with severe pancreatitis.

Dynamic MRI of the pancreas--gadolinium enhancement in normal tissue

The purpose of this study was to measure signal enhancement over time in the normal pancreas after intravenous bolus infection of gadolinium-DTPA (Schering Health Care Ltd) (Gd-DTPA). Data was obtained from 25 patients with no evidence of pancreatic disease before, immediately after and over a 2 min period following injection of Gd-DTPA (Magnevist 0.2 ml per kg). Scans were obtained using a turboFLASH sequence which allows 11 slices to be acquired during a single breathhold period of 19 s. Five mm thick slices were acquired in the coronal/oblique plane at 0.5 mm intervals. A pre-contrast block of slices was obtained followed by dynamic post-contrast scanning with the first of four acquisitions beginning 12-15 s after bolus injection. A 10 s interval between each acquisition was selected to allow the patients to breathe. Signal intensity for each acquisition was measured for the pancreatic head and tail and also for the liver. All values were normalized to fat. Marked enhancement of the pancreas was seen in all cases with peak enhancement occurring in the first and second post-contrast acquisition. The pancreatic duct was more easily seen after contrast injection.