Pancreatic disease: prospective comparison of CT, ERCP, and 1.5-T MR imaging with dynamic gadolinium enhancement and fat suppression

Dynamic High-Field MR Imaging in Experimental Porcine Acute Pancreatitis

The effects of acute pancreatitis on MR imaging signal intensities (SIs) were determined in an experimental study at 1.0 T. Oedematous pancreatitis was induced in 9 piglets and haemorrhagic pancreatitis in 11 piglets. Each animal served as its own control for MR imaging before and after induction of pancreatitis. T1-weighted spin echo (450/15 ms) and dynamic turbo FLASH (flip angle 8°) sequences were used without contrast medium in testing the stability of the SI measurements. There was no significant difference in the SI-versus-time curves of the pancreas in piglets with oedematous and haemorrhagic pancreatitis. However, the difference in mean SIs between healthy and diseased piglets was significant. Thus, although non-contrast MR may be useful in the diagnosis of acute pancreatitis, it does not distinguish between oedematous and haemorrhagic pancreatitis.

Magnetic resonance imaging of retroperitoneal interfascial plane involvement in acute pancreatitis

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Role of magnetic resonance imaging in the detection and characterization of solid pancreatic nodules: An update

Pancreatic ductal adenocarcinoma is the most common malignant tumor of the pancreas. The remaining pancreatic tumors are a diverse group of pancreatic neoplasms that comprises cystic pancreatic neoplasms, endocrine tumors and other uncommon pancreatic tumors. Due to the excellent soft tissue contrast resolution, magnetic resonance imaging (MRI) is frequently able to readily separate cystic from noncystic tumors. Cystic tumors are often easy to diagnose with MRI; however, noncystic non-adenocarcinoma tumors may show a wide spectrum of imaging features, which can potentially mimic ductal adenocarcinoma. MRI is a reliable technique for the characterization of pancreatic lesions. The implementation of novel motion-resistant pulse sequences and respiratory gating techniques, as well as the recognized benefits of MR cholangiopancreatography, make MRI a very accurate examination for the evaluation of pancreatic masses. MRI has the distinctive ability of non-invasive assessment of the pancreatic ducts, pancreatic parenchyma, neighbouring soft tissues, and vascular network in one examination. MRI can identify different characteristics of various solid pancreatic lesions, potentially allowing the differentiation of adenocarcinoma from other benign and malignant entities. In this review we describe the MRI protocols and MRI characteristics of various solid pancreatic lesions. Recognition of these characteristics may establish the right diagnosis or at least narrow the differential diagnosis, thus avoiding unnecessary tests or procedures and permitting better management.

Pancreatic adenocarcinoma: MRI conspicuity and pathologic correlations

PURPOSE

To identify the MRI sequences producing the greatest pancreatic adenocarcinoma conspicuity and to assess correlations linking MRI signal intensity and apparent diffusion coefficient to histopathological findings.

METHODS

We retrospectively included 22 patients with pancreatic adenocarcinoma who underwent MRI (1.5 or 3 T) before surgical resection. Fat-suppressed (FS) T1- and T2-weighted sequences; 3D FS dynamic T1-weighted gadolinium-enhanced gradient-echo (GRE) imaging at the arterial, portal, and delayed phases; and diffusion-weighted imaging (DWI) with b values of 600-800 s/mm(2) were reviewed. On each sequence, we assessed tumor conspicuity both qualitatively (3-point scale) and quantitatively (tumor-to-proximal and -distal pancreas contrast ratios), and we performed paired Wilcoxon tests to compare these data across sequences. We evaluated correlations between histopathological characteristics and MRI features.

RESULTS

21/22 (95%) tumors were hypointense by 3D FS T1 GRE arterial phase imaging, which produced the greatest tumor conspicuity (p ≤ 0.02). By DWI, 5/20 (25%) of tumors were isointense. The correlation between size by histology and MRI was strongest with DWI. A progressive enhancement pattern was associated with extensive and dense fibrous stroma (p ≤ 0.03).

CONCLUSIONS

3D FS T1 GRE arterial phase imaging produces greater pancreatic adenocarcinoma conspicuity compared to DWI but underestimates tumor size. DWI provides the best size evaluation but fails to delineate the tumor in one-fourth of cases.

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.

Peripancreatic fat invasion is an independent predictor of poor outcome following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma

BACKGROUND

Following pancreaticoduodenectomy for pancreatic ductal adenocarcinoma (PDAC), identification of peripancreatic fat tumor invasion promotes a tumor to stage T3. We sought to understand better the impact of histological peripancreatic fat invasion on prognosis and site of recurrence in a cohort of patients with PDAC.

METHODS

We analyzed the patient demographics, outcome, and recurrence data that had been prospectively collected in 189 consecutive PDAC undergoing potentially curative pancreaticoduodenectomy between 1996 and 2009. Pathological features were reassessed for all patients. Survival outcome was compared using Kaplan-Meier/Cox proportional hazards analysis. The primary site of recurrence was defined as either locoregional or distant metastases.

RESULTS

The median survival of this PDAC cohort was 18.9 months (95% confidence interval (CI) 15.7-22.2). Histological peripancreatic fat invasion was evident in 51 (27%) patients and was associated with lymph node metastases (p = 0.004) and larger tumor size (p = 0.015). The presence of peripancreatic fat invasion was associated with reduced overall survival following resection (12.4 months [95% CI 9.9-15.0]) when compared to those patients with no evidence of fat invasion (22.6 months [95% CI 18.5-26.7]; p < 0.0001). By multivariate survival analysis, independent predictors of overall survival included tumor grade (p = 0.002), lymph node involvement (p = 0.025), resection margin status (p = 0.003), venous invasion (p = 0.045), and peripancreatic fat invasion (p = 0.007). Invasion into the pancreatic fat was significantly associated with the primary site of recurrence being locoregional failure (p = 0.002).

CONCLUSIONS

Peripancreatic fat invasion was identified as being an independent predictor of poor outcome following pancreaticoduodenectomy for PDAC. Additionally, the presence of peripancreatic fat invasion was associated with locoregional disease as the primary site of recurrence. This may have implications for the staging of PDAC and potentially require incorporation into future staging systems to improve outcome stratification.

Extrapancreatic neural plexus invasion by pancreatic carcinoma: characteristics on magnetic resonance imaging

BACKGROUND

Our objective is to study the characteristics of extrapancreatic neural plexus invasion by pancreatic carcinoma on MR imaging.

METHODS

20 patients with both pancreatic carcinoma and extrapancreatic neural plexus invasion confirmed by pathology were recruited in this study. MR imaging was performed within 1 month before surgery. On MR images, signal intensity at the site of potential extrapancreatic neural plexus invasion, lymph nodes and tumor size were noted. The relationship of extrapancreatic neural plexus invasion to these findings was analyzed.

RESULTS

Signs of extrapancreatic neural plexus invasion were depicted on MR imaging in 80% of patients, which included streaky and strand-like signal intensity structure in fat tissue in 50% of patients and irregular masses adjacent to tumor in 30%. Signal intensity at invasion site was similar to that of pancreatic carcinoma. The frequencies of patients with vascular invasion and with lymph nodes larger than 5 mm were, respectively, 50% and 55%. Tumor diameter was 24 +/- 7 mm on MR imaging. Extrapancreatic neural plexus invasion was correlated with vascular invasion (r = 0.58, P < 0.005), slightly related with lymphadenopathy (r = 0.35, 0.1 > P > 0.05), but not related with tumor size.

CONCLUSION

MR imaging is useful to depict extrapancreatic neural plexus invasion by pancreatic carcinoma.

Prediction of post-operative pancreatic fistula in pancreaticoduodenectomy patients using pre-operative MRI: a pilot study

BACKGROUND

Post-operative pancreatic fistula (POPF) is one of the most fearful complications which may occur after pancreaticoduodenectomy (PD). The methods used to predict POPF pre-operatively have not been studied in great detail. We analyzed correlation between various parameters related to PD including pre-operative magnetic resonance imaging (MRI) signal intensity (SI), pathology of pancreatic fibrosis and occurrence rates of POPF, and verified that MRI SI results could be the determining values for pre-operative prediction of POPF.

METHODS

From January 2005 to August 2006, we retrospectively examined 43 cases of PDs by reviewing abdominal MRI findings, degree of fibrosis of remnant pancreatic stump, and other surgery-related parameters.

RESULTS

POPF encountered in PD were 11 cases (25.6%). Operation time and degree of fibrosis of remnant pancreatic cut surface were related to POPF (P= 0.030, P= 0.010). The pancreas-liver SI ratio (PLSI) between fistula group and no fistula group was -0.0009 +/- 0.2 and -0.1297 +/- 0.2, respectively (P= 0.0004). The pancreas-spleen SI ratio (PSSI) in each group was 0.423 +/- 0.25 and 0.288 +/- 0.32, respectively (P= 0.014). Using quantitative analysis, the SI ratios were 1.27 and 0.66 in each group (P= 0.013).

CONCLUSIONS

When analyzing the results of POPF in 43 patients who underwent PD, PLSI, PSSI and qualitative analysis, fistula group differed significantly from no fistula group. Using these results, it will be helpful for us to predict the occurrence of POPF pre-operatively using MRI in PD patients.

Magnetic resonance imaging of adenocarcinoma of the pancreas

Magnetic resonance imaging (MRI) is a valuable tool in the assessment of the full spectrum of pancreatic disease. A standard MR protocol including noncontrast T1-weighted fat-suppressed and dynamic gadolinium-enhanced gradient-echo imagings is sensitive for the evaluation of pancreatic cancer. Optimal use of MRI in the investigation of pancreatic cancer occurs in the following circumstances: (1) detection of small non-contour-deforming tumors, (2) evaluation of local extension and vascular encasement, (3) determination of the presence of lymph node and peritoneal metastases, and (4) determination and characterization of associated liver lesions and liver metastases. The objective of this study was to describe the attribute of MRI for evaluating pancreatic cancer.

MR imaging for predicting the recurrence of pancreatic carcinoma after surgical resection

OBJECTIVE

To study the relationship of characteristics of pancreatic carcinoma on MR imaging to tumor recurrence time after surgical resection.

MATERIALS AND METHODS

Twenty-seven patients with pancreatic carcinoma were followed up at least 2 years after surgical resection of the tumor. All patients had MR imaging within 1 month before surgery. The tumor's size, signal intensity, local and vascular invasion, abdominal lymphadenopathy on MR imaging and the positive surgical margin were noted. The results from MR imaging were compared with the duration after surgery until tumor recurrence and with the positive surgical margin.

RESULTS

59% of patients had various degree of extrapancreatic invasion. The tumor recurrence times were, respectively, 24+/-21 months and 26+/-29 months in patients with and without vascular invasion (P=0.79). The combination of vascular with local invasion showed a correlation to the time of tumor recurrence (r=-0.34; P<0.05). Patients with positive surgical margins had a higher local invasion score on MR imaging and a shorter recurrence time than those with negative surgical margins. The number and size of lymph nodes were not related with tumor recurrence time.

CONCLUSION

MR imaging was useful for predicting the recurrence of pancreatic carcinoma after surgical resection. Local invasion associated with and without vascular invasion on MR imaging was the indicator for the tumor recurrence.

Chronic pancreatitis: ultrasound, computed tomography, and magnetic resonance imaging features

Chronic pancreatitis is a progressive, irreversible inflammatory and fibrosing disease of the pancreas with clinical manifestations of chronic abdominal pain, weight loss, and permanent pancreatic exocrine and endocrine insufficiency. In the United States, a long history of heavy alcohol consumption is the most common cause of chronic pancreatitis. This review discusses the different modalities such as computed tomography, transabdominal and endoscopic ultrasound, magnetic resonance imaging/magnetic resonance cholangiopancreatography, and endoscopic retrograde cholangiopancreatography available to image chronic pancreatitis, along with their advantages and limitations. In addition, topics such as groove pancreatitis and autoimmune pancreatitis are examined, along with a discussion of distinguishing chronic pancreatitis from pancreatic adenocarcinoma.

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.

[Imaging of pancreatic adenocarcinoma]

Pancreatic cancer remains the fourth most common cause of cancer death. Surgery remains the only option for cure. Accurate diagnosis and staging are essential for appropriate management of patients with pancreatic cancer. This paper reviews the state of the art for imaging modalities in the diagnosis and staging of pancreatic adenocarcinoma. The crucial role of CT has increased with the new generation of multidetector CT.

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.

Comparison of qualitative and quantitative measurements on unenhanced T1-weighted fat saturation MR images in predicting pancreatic pathology

PURPOSE

To evaluate the accuracy of signal intensity (SI) analysis on unenhanced fat-suppressed T1-weighted MR images in the diagnosis of pancreatic disease and to compare subjective interpretation with different quantitative measurements.

MATERIALS AND METHODS

The pancreas was evaluated in 159 patients (86 normal and 73 with pancreatic disease) with spoiled gradient echo (GRE) T1-weighted fat saturation MR images. The relative SI of the pancreas to liver and spleen was quantitatively measured using regions of interest (ROIs) and qualitatively assessed by two independent observers.

RESULTS

The mean values between a normal and an abnormal pancreas with pancreas-liver ratios of 0.14 +/- 0.37 vs. -0.32 +/- 0.24, respectively, and pancreas-spleen ratios of 0.89 +/- 0.55 vs. 0.02 +/- 0.43, respectively, were significantly different (P < 0.001). The pancreas-liver SI ratio was significantly better than the pancreas-spleen ratio throughout the disease group (area under the receiver operating characteristic (ROC) curve +/- SD; 0.92 +/- 0.02 for pancreas-liver vs. 0.86 +/- 0.03 for pancreas-spleen, P < 0.01), and after excluding cases of acute pancreatitis (0.96 +/- 0.02 for pancreas-liver vs. 0.89 +/- 0.03 for pancreas-spleen, P < 0.01). There was no statistically significant difference between quantitative and qualitative analysis (area under the ROC curve +/- SD; 0.93 +/- 0.02 vs. 0.93 +/- 0.02 for the entire disease group; excluding acute pancreatitis 0.96 +/- 0.02 vs 0.97 +/- 0.02) for the diagnosis of pancreatic disease when using liver as internal standard. The interobserver concordance was very good (kappa > 0.71). The sensitivity of visual liver comparison was 80% in the entire disease group and 91% after the cases of acute pancreatitis were excluded, while specificity was 93%.

CONCLUSION

The pancreas-liver ratio is the best quantitative means of distinguishing normal from abnormal pancreas. Visual observation by experienced observers (qualitative measurement) was just as accurate as quantitative measurement. Detection of pancreatic pathology can be made with high accuracy by visually comparing the SI of the pancreas with that of the normal liver.

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.

Chronic pancreatitis. The problems of diagnostic criteria

The diagnostic criteria for chronic pancreatitis proposed by the Japan Pancreas Society (JPS) classified chronic pancreatitis into (i) definite; (ii) probable, and (iii) possible chronic pancreatitis, excluding obstructive, inflammatory (autoimmune) and tumor-forming pancreatitis from the definition of chronic pancreatitis. In the JPS Criteria, imaging studies, pancreatic function tests, and histological findings are independent of each other, and thus the diagnosis of chronic pancreatitis is made if one of the criteria is satisfied, regardless of the etiology of the chronic pancreatitis. The current diagnostic criteria for chronic pancreatitis depend on abnormalities of the duct system, such as low bicarbonate output, dilation of main pancreatic duct and duct branches, and calculi in the ducts by imaging studies. We revealed that the difference between reversible and irreversible pancreatitis in experimental animals is dependent on the degree of damage of the duct epithelium where pancreas progenitor cells exist. Thus, chronic pancreatitis diagnosed by the current criteria based on abnormalities of the duct system is irreversible. In contrast, the epithelium of the ducts is usually preserved in obstructive and autoimmune pancreatitis in that both structural and functional changes recover almost completely when the obstruction is removed or the inflammatory changes disappear following steroid administration. Even in chronic pancreatitis defined as irreversible, there must be a reversible stage during its clinical course. There is a need to develop biological markers and/or imaging procedure to detect chronic pancreatitis at its reversible stage.

Imaging of pancreatic adenocarcinoma with emphasis on multidetector CT

Pancreatic adenocarcinoma is the fourth most frequent cause of cancer-related death. The incidence is increasing and the overall survival has altered little in recent years. Moreover, patients usually present late with inoperable disease and curative resection by standard pancreatico-duodenectomy (Whipple's procedure) is associated with significant morbidity. It should only be attempted in that small group of patients lacking radiological evidence of advanced disease. Despite the recent advances in body magnetic resonance imaging (MRI) and endoscopic ultrasound (EUS), computed tomography (CT) is the mainstay of staging in most centres and the recent development of multidetector CT machines (MDCT) has raised hope of an improvement in preoperative staging. This review focuses on the CT of pancreatic adenocarcinoma with particular emphasis on examination technique and on those criteria that determine resectability.

Imaging for the diagnosis and staging of periampullary carcinomas

Multiple imaging modalities are available for investigating patients with a suspected periampullary neoplasm. The relative utility of each imaging modality is discussed regarding its role in diagnosis and staging. A general imaging approach to patients with a distal biliary obstruction also is presented.

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.

Juxtapapillary diverticulum: findings on MRI

The purpose of our study was to describe the imaging findings of juxtapapillary diverticulum on magnetic resonance imaging (MRI). The MRI and magnetic resonance cholangiopancreatography (MRCP) examinations of 14 patients with juxtapapillary diverticula that were diagnosed on endoscopic retrograde cholangiopancreatography (ERCP) (N = 8) or endoscopy (N = 6) were retrospectively evaluated. T1-weighted spoiled gradient-echo, T2-weighted half Fourier single shot fast spin-echo (HASTE), and T2-weighted True FISP (fast imaging with steady state precession) images and thin-slice MRCP images were obtained on all patients. In five patients, diluted gadolinium DPTA (1/100) was used as an oral contrast. T2-weighted True FISP and HASTE images demonstrated air-fluid levels within all diverticula. Hyperintense oral contrast on T1-weighted spoiled gradient-echo images aided detection of the smaller diverticula. MRCP images obtained in the coronal plane best demonstrated the relationship of the diverticula to the papilla. MRI with the use of HASTE, True FISP, and oral contrast-enhanced T1-weighted sequences was able to depict juxtapapillary diverticula in our series.

Juxtapapillary diverticulum: findings on CT and MRI

The purpose of this study was to evaluate the computed tomography (CT) and magnetic resonance imaging (MRI) features of juxtapapillary diverticulum. CT and/or MRI examinations of 12 patients were evaluated. The size, location of the diverticula and imaging findings of associated pancreaticobiliary disease were assessed. On CT, oral contrast air level was the characteristic imaging feature. On MRI, T2-weighted images demonstrated the air fluid level with hyperintense fluid and signal void air level above. Associated imaging findings were dilated common bile duct (CBD), cholecystitis, cholecystolithiasis and chronic pancreatitis.

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

PURPOSE

To assess whether measuring the pattern of pancreatic enhancement on gadolinium chelate dynamic magnetic resonance imaging (MRI) is helpful for diagnosis of suspected early or mild chronic pancreatitis.

MATERIALS AND METHODS

In this retrospective study, 24 patients with suspected early or mild chronic pancreatitis, classified by imaging criteria of equivocal chronic pancreatitis (ultrasound, computed tomography [CT] or ERCP) grading, had dynamic MRI that included unenhanced, arterial dominant, early venous, and late venous phases of contrast enhancement. Twenty patients without pancreatic diseases also had the dynamic sequence as a control group. The signal intensity was measured at the pancreatic head, body, and tail on all phases, and for each, the signal intensity ratio (SIR, the signal intensity in postcontrast divided by that in precontrast) was calculated. Two radiologists independently reviewed the images of the patients with suspected early or mild chronic pancreatitis for pancreatic morphologic abnormalities without knowing the results of signal intensity measurements.

RESULTS

On unenhanced images, there was no significant difference of signal intensity between control and pancreatitis groups (P < 0.05). In the pancreatitis group, but not in the control group, the unenhanced signal intensity of the pancreatic head and body were significantly higher than that of the tail (P < 0.05). In the control group, the greatest enhancement (highest SIR) after injection was in the arterial phase (1.89 +/- 0.31), significantly higher than that in the early venous phase (1.68 +/- 0.17, P < 0.01) and in the late venous phase (1.61 +/- 0.15, P < 0.001). The pancreatitis group, however, had an arterial phase SIR (1.65 +/- 0.23) that was significantly lower than its early venous phase SIR (1.75 +/- 0.22, P < 0.05) and lower than the arterial phase SIR of the control group (P < 0.01). The presence of an SIR less than 1.73 in the arterial phase and/or a delayed peak enhancement after contrast agent administration had a sensitivity and specificity of diagnosing early or mild chronic pancreatitis of 92% and 75%, respectively. This sensitivity was significantly higher than the sensitivity of 50% for diagnosis based on morphologic abnormalities (P < 0.05).

CONCLUSION

Measuring pancreatic signal intensity on gadolinium chelate dynamic MRI is helpful for diagnosing early or mild chronic pancreatitis, especially before apparent pancreatic morphologic or signal intensity changes are present.

Imaging of chronic pancreatitis

This article reviews the recognized findings of chronic pancreatitis on CT and endoscopic retrograde cholangiopancreatography. It also discusses more recently developed techniques including gadolinium-enhanced MR imaging, MR cholangiopancreatography, and endoscopic ultrasound. Variants of chronic pancreatitis and difficulties in differentiating pancreatic neoplasms from inflammatory pancreatic masses are also discussed.

MR imaging of the pancreas: a practical approach

This article reviews the current practical MRI techniques in assessment of the pancreas. With the comprehensive "one-stop-shopping" approach, the great majority of pancreatic diseases can be detected and characterized by the use of a combination of T1, T2-weighted, MRCP, and fat-suppressed T1-weighted dynamic post-gadolinium SGE sequences. This approach may provide the clinician with information regarding the site, nature, and staging of pancreatic tumor in a single setting. In many institutions worldwide, however, including our own, CT remains the main imaging method for the assessment of acute pancreatic diseases, due largely to its wide availability. MR imaging is reserved for the indications listed above, most importantly, the detection of small and non-organ-deforming pancreatic ductal adenocarcinoma, islet cell tumors, choledocholithiasis and pancreatic duct calculi, cholangiocarcinomas, and in cases of pancreatic head enlargement with no mass discernable on CT.

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.

Advances in imaging for pancreatic disease

Pancreatic imaging is an essential tool in the early diagnosis and staging of pancreatic disease. This review analyzes the most recent advances in pancreatic imaging. The specific modalities discussed include helical computed tomography (HCT) and multislice CT (MSCT), CT angiography, magnetic resonance imaging (MRI), magnetic resonance cholangiopancreatography (MRCP), and positron emission tomography (PET). At present, MSCT is generally viewed as the most efficient modality for initial detection and staging of pancreatic carcinoma, with an accuracy rate of about 95% to 97% for initial detection and virtually 100% for staging. CT is also the initial imaging modality used in evaluation of acute pancreatitis. However, recently, MRI has been viewed increasingly as a more precise diagnostic tool in this subgroup of patients. MRCP has been accepted as the primary imaging technique in the diagnosis of chronic pancreatitis. PET imaging, on the other hand, has an increasing role in the staging of pancreatic carcinoma, for which it may be the modality of choice in detection of extrapancreatic metastasis.

Magnetic resonance imaging in patients with pancreatitis: evaluation of signal intensity and enhancement changes

PURPOSE

To evaluate the utility of unenhanced and enhanced T1-weighted fat-suppressed (T1-FS) magnetic resonance imaging (MRI) in detecting pancreatitis.

MATERIALS AND METHODS

1.5-T MRI was performed in 25 patients with acute and 23 patients with chronic pancreatitis and in 20 control subjects without known pancreatic disease. T1-FS spin-echo and contrast-enhanced arterial-predominant (DYN1) and portal-predominant (DYN2) fast multiplanar spoiled gradient-echo (FMPSPGR) sequences were evaluated. These three sets of images were evaluated both subjectively for decreased or heterogeneous signal intensity (rating scale, 0-3) and objectively (region of interest (ROI)) in the head, body, and tail of the pancreas, in each patient.

RESULTS

Good correlation between subjective assessment and objective data was demonstrated. The T1-FS sequence showed an abnormality with greater frequency (T1-FS > DYN1, 81/144 scores; T1-FS = DYN1, 63/144 scores; T1-FS < DYN1, 0/144 scores) and magnitude (average subjective score, 2.48 vs. 1.74; P < 0.0003) than that of the contrast-enhanced FMPSPGR (decreased or heterogeneous enhancement). The overall sensitivity and specificity of MRI was 92% and 50%, respectively. On the basis of signal intensity and enhancement, MRI was not able to differentiate acute from chronic pancreatitis.

CONCLUSION

MRI was highly sensitive for disease detection, particularly using the T1-FS sequence, but using the sequences described, was not able to differentiate acute from chronic pancreatitis.

Radiologic diagnosis and staging of pancreatic ductal adenocarcinoma

This article presents imaging modalities in the diagnosis and staging of pancreatic ductal adenocarcinoma. Magnetic resonance imaging (MRI) and endoscopic ultrasonography (EUS) have the highest accuracy in detection of pancreatic cancer. MRI and EUS have similar accuracy in determining the local extent of pancreatic cancer. Angiography, computed tomography (CT) angiography and EUS are similarly accurate in evaluating peripancreatic vascular involvement. MRI is the superior method for detecting liver metastases and peritoneal implants of pancreatic ductal adenocarcinoma. Endoscopic retrograde cholangiopancreatography (ERCP) and magnetic resonance cholangiopancreatography (MRCP) are used to assess the biliary tract of patients with pancreatic cancer. Positron emission tomography (PET) is useful in distinguishing pancreatic cancer from focal pancreatic inflammation.

Pancreatic carcinoma and fast MR imaging: technical considerations for signal intensity difference measurements

The aim of the study was to find the fast magnetic resonance imaging (MRI) sequence with the best conspicuity of pancreatic lesions at 1.0 T and 1.5 T. A total of 51 patients were studied. At 1.0 T, 22 patients with verified malignant pancreatic lesions were studied using the T1-weighted breath-hold spoiled Gradient Echo 2D FLASH(75) or FLASH(80) sequences, both non-enhanced and enhanced with gadolinium. The relative signal intensity difference (SIDR) between lesion and pancreas was measured. At 1.5 T, 20 patients with primary malignant lesions of the pancreas, and nine patients with 13 benign cystic lesions were examined with the breath-hold T2-weighted TrueFISP, HASTE, T1-weighted 2D FLASH(80) and FLASH(50) fat saturation sequences, the latter also enhanced. The signal intensity (SI) values of the pancreas and lesions as well as the pancreatic standard deviation (S.D.) were assessed, and the contrast-to-noise ratio (C/N) was determined. Statistical significances were calculated using an analysis of variance. No statistically significant difference between the sequences used in the conspicuity of cancer was found, either at 1.0 T or at 1.5 T. At 1.5 T, the T2-weighted TrueFISP and HASTE sequences could differentiate benign, cystic lesions from malignant lesions.

The role of diagnostic radiology in pancreatitis

Acute pancreatitis is a frequent inflammatory and necrotic process of pancreas and peripancreatic field. To detect the presence of infected or sterile necrotic components and hemorrhage of the pancreatic paranchyma is important for therapeutic approach. Chronic pancreatitis is characterized by irreversible exocrine dysfunction, progressive loss of pancreatic tissue and morphological changes of the pancreatic canal. Imaging modalities play a primary role in the management of both acute and cronic pancreatitis. CT and MR imaging confirm the diagnosis and detect the severity of disease. In chronic pancreatitis, MRCP after Secretin administration, Spiral CT and endoscopic US seems to replace diagnostic ERCP. However differentiation of pseudotumor of chronic pancreatitis from the pancreatic carcinoma is difficult with either imaging modalities.

Efficacy of three-dimensional fast imaging with steady precession dynamic MR imaging in evaluating pancreatic ductal adenocarcinoma

To compare the diagnostic efficacy of three-dimensional fast imaging with steady precession (3D-FISP) dynamic MR imaging in assessing pancreatic ductal adenocarcinoma with conventional MR imaging and helical CT, 15 patients with surgically proven pancreatic ductal adenocarcinoma were studied. Contrast-to-noise ratio (CNR) of the tumor, tumor detectability, local tumor extension, and vascular involvement were evaluated for all techniques. The results indicate that 3D-FISP dynamic MR imaging may improve the imaging assessment of pancreatic ductal adenocarcinoma.

MRI with mangafodipir trisodium in the detection and staging of pancreatic cancer

The purpose of this study was to compare prospectively computed tomography (CT) and magnetic resonance (MR) imaging before and after mangafodipir trisodium infusion for the detection and staging of focal pancreatic lesions. From November 1996 to October 1997, 43 consecutive patients suspected to have a focal pancreatic lesion were included in a phase III study. Triphasic helical CT was performed, as well as MRI at 1.5 T, as follows: axial T1-weighted (T1w) turbo spin echo (TSE), spectral presaturation with inversion recovery (SPIR) T1w TSE, T1w turbo field echo (TFE), and SPIR T2w TSE before and after mangafodipir trisodium (0.01 mmol/ml, 0.5 ml/kg) infusion. Imaging results were correlated with surgery, laparoscopy, laparoscopic ultrasound, and biopsy. Objective measurements were performed by measuring signal intensities (SIs) of lesion and parenchyma and calculating contrast indexes (CIs) and contrast-to-noise-ratios (CNRs) to assess the delineation of the tumor. SIs were correlated with four phantom standards with a known SI. Thirty-eight pancreatic adenocarcinomas were present, as well as one cystadenoma, two papillomas, and two cases of focal pancreatitis. SI measurements revealed significant increases in CIs for the lesion compared with the parenchyma in T1w TSE (69.7 vs 152.7; P = 0. 0003) and T1w TFE (107.8 vs 194.2; P = 0.0002). These series also revealed significant increases in CNRs (for T1w TSE: 9.7 vs 13.0; P = 0.0407 and for T1w TFE: 14.5 vs 26.1; P = 0.0001). In the other series, there was no significant increase. CT detected 38 lesions, MRI without mangafodipir trisodium detected 39 lesions, and MRI with mangafodipir trisodium detected 40 lesions, giving detection accuracy rates of 88%, 91%, and 93%, respectively. Staging accuracy rates for vascular ingrowth were 81%, 75%, and 81%, respectively. Overall staging accuracy rates were 57%, 54%, and 54%, respectively, mostly due to undetected small metastases in the peritoneum, omentum, or liver (< 1 cm). This study indicates that a) MRI after mangafodipir trisodium gives a better delineation of the tumor in T1w series, but b) does not significantly improve the detection rate and staging accuracy of focal pancreatic lesions over MRI without this contrast medium.

Extrahepatic abdominal imaging in patients with malignancy: comparison of MR imaging and helical CT in 164 patients

The purpose of this study was to compare the performance of magnetic resonance (MR) imaging using currently available techniques with contrast-enhanced single-phase helical computed tomography (CT) in depicting extrahepatic disease in patients with malignancy. At two institutions, 164 patients with known or suspected malignancy underwent abdominal imaging with contrast-enhanced helical CT and MR imaging. The prospective interpretations of the CT scans and MR examinations were used to assess the sensitivity of each imaging test in detecting benign and malignant extrahepatic disease at 17 anatomic sites. Imaging findings were compared with results of surgery in 57 patients and with the combined results of image-guided biopsy, follow-up cross-sectional imaging studies, other concurrent imaging tests, and clinical follow-up. For the 164 patients, helical CT scans depicted 221 of 316 (70%) sites of proven extrahepatic tumor compared with 288 sites (91%) (P < 0.0001) for MR imaging. For the 57 patients who underwent exploratory laparotomy, helical CT scans depicted 101 of 154 (66%) findings of surgically confirmed extrahepatic tumor compared with MR imaging, which depicted 139 sites (90%) (P < 0.0001). Anatomic sites at which MR imaging showed a significantly greater detection of extrahepatic tumor included the peritoneum, bowel, and vascular and osseous structures. For depiction of benign extrahepatic disease, there was no significant difference between helical CT and MR imaging. MR imaging, using currently available T1-weighted, RARE T2-weighted, and gadolinium-enhanced imaging, is effective in depicting extrahepatic disease in patients with malignancy. Compared with single-phase helical CT scanning, MR imaging shows an advantage in depicting tumor involving the peritoneum, omentum, bowel, and osseous and vascular structures.

Magnetic resonance cholangiopancreatography in cystic lesions of the pancreas

There are few reports about magnetic resonance cholangiopancreatography (MRCP) in cystic lesions of the pancreas (KLP). For this reason, we have undertaken a prospective study evaluating the diagnostic efficiency of MRCP as compared with ultrasonography. Twenty-four patients with KLP were examined with magnetic resonance imaging (MRI), and standard and cholangiopancreatography. There were seven cases of cysts associated with acute pancreatitis, 11 patients with KLP and chronic calcifying pancreatitis, five cases of cystic neoplasms of the pancreas, and one polycystic disease of the gland. All cases were first submitted to ultrasonography, which failed to diagnose only a case of cyst associated with chronic pancreatitis depicted by MRCP. We used a GE Signa Horizon 1.5-T system (20 examinations) and a Siemens Magneton Plus 1.5-T machine (four examinations). Eleven patients were operated on. In all cases, it was possible to identify the cysts, the main pancreatic duct and the biliary tree, and verify the relationship of the cyst with neighboring organs. Communication of the cyst with the main pancreatic duct was described in five instances, but we cannot be sure that MRCP would have depicted all cyst-duct communications. The MRI and MRCP images were confirmed by surgery in the 11 operated-on cases. The diagnosis of duct alterations and small pancreatic stones in initial cases of chronic calcifying pancreatitis may be problematic. Clinical findings are very important data to be considered in the differential diagnosis of KLP. Together with the clinical data, MRCP is a very important technique in the diagnostic and therapeutic decision making of KLP. Standard magnetic resonance is advisable as part of the examination in all cases. MRCP is not invasive, is reliable if one knows its limitations, and the patient can return at once to his activities. It allows the analysis of many variables in one examination, contributing to better therapy.

Pancreas and peripancreatic vessels: effect of imaging delay on gadolinium enhancement at dynamic gradient-recalled-echo MR imaging

PURPOSE

To investigate the effect of imaging delay on gadolinium enhancement of the pancreas and peripancreatic vessels at dynamic gradient-recalled-echo magnetic resonance (MR) imaging of the pancreas.

MATERIALS AND METHODS

Dynamic MR images were obtained after intravenous bolus injection of gadopentetate dimeglumine in 75 patients with no pancreatic malignancies. Test-bolus imaging was performed to determine aortic transit time in individual patients. Patients were randomly assigned so that the middle of k space was acquired at 5, 15, 25, 35, or 45 seconds after arrival of contrast material in the abdominal aorta. Mean signal intensities of pancreas, liver, and peripancreatic vessels were measured, and images were qualitatively assessed by two radiologists.

RESULTS

The best pancreatic enhancement occurred at a delay of 15 seconds (P <.05). The best enhancement of the liver and peripancreatic vessels occurred at 25 seconds or later (P <.05). Qualitatively, the best images of the pancreas were obtained at 15 seconds, and the best images of the liver and peripancreatic vessels were obtained at 25 seconds or later.

CONCLUSION

Biphasic imaging at 15 and 45 seconds or later after arrival of contrast material in the abdominal aorta is a practical method for acquisition of high-quality dynamic gradient-recalled-echo MR images of the pancreas.

Biliary obstruction: findings at MR cholangiography and cross-sectional MR imaging

Twenty-two patients with malignant biliary obstruction and 21 patients with suspected obstruction of biliary-enteric anastomoses were evaluated over a 12-month period with magnetic resonance (MR) cholangiography and cross-sectional MR imaging. In patients with malignant obstruction, MR cholangiography helped accurately determine the status of the biliary ductal system by identifying the exact location and extent of the obstruction and the severity of duct dilatation. In so doing, MR cholangiography helped determine whether percutaneous transhepatic cholangiography with antegrade stent placement or retrograde cholangiography with stent placement constituted the more suitable treatment. Cross-sectional MR imaging was necessary to identify the organ of tumor origin, define the tumor margins, and determine the stage of disease. This information helped evaluate the appropriateness of curative surgical therapy versus palliative drainage procedures. In patients with biliary-enteric anastomoses, MR cholangiography clearly depicted the site of the anastomosis and demonstrated the status of the intrahepatic ducts, thereby helping determine which patients would benefit from undergoing antegrade duct cannulation with a drainage procedure or perhaps balloon dilation. In some of these patients, MR cholangiography was sufficient to help plan therapeutic intervention. MR cholangiography also demonstrates the presence and size of biliary stones and associated findings such as intraductal tumor growth. In addition, MR cholangiography may obviate retrograde cholangiography, which can be technically difficult to perform.

MR cholangiopancreatography in malignant biliary obstruction

Malignant lesions of the biliary tract are a frequent occurrence, typically presenting with clinical findings of obstructive jaundice. The authors discuss the role of MR cholangiopancreatography (MRCP) as a second level diagnostic technique, which can provide information regarding not only the location, but also the cause of the obstruction. This can be obtained if MRCP is considered as part of a complete study of the upper abdomen, with acquisition of T1- and T2-weighted images. The "all-in-one" approach may provide the identification, characterization, and staging of the lesion, giving the clinician all the information necessary for the planning of adequate treatment. Typical MR features of cholangiocarcinoma are provided, as well as conventional MR and MRCP findings in pancreatic carcinoma, periampullary carcinoma, and biliary obstruction secondary to hilar lymphadenopathy and metastatic lesions.

Pancreatic imaging. New modalities

This article discusses the techniques and applications of the newest pancreatic cross-sectional imaging modalities. The specific modalities that are discussed include helical computed tomography with dual phase imaging and three-dimensional computer rendering techniques, magnetic resonance imaging and magnetic resonance cholangiopancreatography, endoscopic and intraductal pancreatic sonography, and radionuclide scintigraphy using positron emission scanning and somatostatin-receptor imaging.

Local extension of pancreatic carcinoma: assessment with thin-section helical CT versus with breath-hold fast MR imaging--ROC analysis

PURPOSE

To compare contrast material-enhanced thin-section helical CT with breath-hold contrast-enhanced MR imaging for sensitivity in the detection of pancreatic adenocarcinoma and for accuracy in local tumor staging.

MATERIALS AND METHODS

Fifty-seven patients (37 men, 20 women aged 42-28 years) suspected of having pancreatic adenocarcinoma were examined. The final diagnosis was confirmed at surgery to be pancreatic cancer in 31 patients; the other 26 patients were deemed not to have pancreatic cancer. All patients underwent both CT and MR imaging (turbo spin-echo and fast low-angle shot) studies. Image quality and pancreatic enhancement were subjectively evaluated. All CT scans and MR images were assessed by two independent observers by using a five-point scale for the detection of tumor and of invasion into the peripancreatic tissue, portal vein, and/or peripancreatic artery. Receiver operating characteristic curves for CT and MR imaging were analyzed.

RESULTS

At visual analysis, pancreatic enhancement at CT and at MR imaging was comparable, but depiction of vessels was superior at helical CT. Detectability of tumor was comparable. Helical CT was significantly superior to MR imaging in diagnostic imaging of invasion into the peripancreatic tissue, portal vein, and/or peripancreatic artery (P < .01).

CONCLUSION

Thin-section dynamic CT is more sensitive than MR imaging for detection of peripancreatic and vascular invasion in patients with pancreatic cancer.

Pancreatic carcinoma versus chronic pancreatitis: dynamic MR imaging

PURPOSE

To determine if dynamic gadolinium-enhanced magnetic resonance (MR) imaging can distinguish chronic pancreatitis from pancreatic carcinoma.

MATERIALS AND METHODS

A retrospective review of MR and pathology examination findings was performed for 24 patients with pancreatic ductal adenocarcinoma and seven with chronic pancreatitis who underwent dynamic gadolinium-enhanced breath-hold spoiled gradient-echo imaging. Arterial, portal, and delayed phase images were obtained after injection of gadopentatate dimeglumine. The MR images of 14 patients without clinical evidence of pancreatic disease were also reviewed as controls. Signal intensity (SI) was measured on the precontrast (pre) and gadolinium-enhanced (post) images of the area of the pancreas sampled at biopsy and of the nontumorous pancreas. Percentage enhancement was defined as SIpre/SIpost x 100.

RESULTS

Normal pancreas showed rapid enhancement that peaked in the arterial or portal phase. For both diseases, T1-weighted images showed hypointense masses with progressive enhancement (differences were significant [P < .05] on only delayed fat-saturated images). Differences in enhancement between either disease state and normal pancreas were significant for at least one phase. Nontumorous pancreas in patients with carcinoma showed gradual enhancement that was significantly different from that of normal pancreas.

CONCLUSION

Chronic pancreatitis and pancreatic carcinoma show abnormal pancreatic enhancement, but the two were not distinguished on the basis of degree and time of enhancement.

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.

Extrahepatic abdominal imaging in patients with malignancy: comparison of MR imaging and helical CT, with subsequent surgical correlation

PURPOSE

To compare state-of-the-art magnetic resonance (MR) imaging with single-phase helical computed tomography (CT) in abdominal screening for extrahepatic disease in patients with proved malignancy.

MATERIALS AND METHODS

Fifty-seven patients with known malignancy underwent abdominal contrast material-enhanced helical CT and MR imaging from 1994 through 1997. Prospective interpretations of CT scans and MR images were used to assess each modality's sensitivity in depicting malignant extrahepatic tumor at 17 anatomic sites. Imaging findings were compared with surgical results in all patients.

RESULTS

Helical CT depicted 101 (66%) of 154 surgically confirmed extrahepatic tumor sites; MR imaging depicted 139 (90%) (P < .001). MR imaging depicted tumor in more patients at 11 of the 17 anatomic sites; at six sites, MR imaging and helical CT were equivalent. MR imaging showed significantly greater depiction of extrahepatic tumor for the peritoneum (P < .05), bowel (P < .01), and mesentery (P < .05). False-negative interpretations would have altered patient care had the extrahepatic tumor remained undetected in 13 patients for helical CT and in six patients for MR imaging.

CONCLUSION

State-of-the-art MR imaging can be used for effective abdominal screening for extrahepatic tumor in patients with malignancy. Compared with single-phase helical CT, MR imaging depicted more sites of extrahepatic tumor and was particularly advantageous for the peritoneum, mesentery, and bowel.

Fast MR imaging for evaluating the pancreaticobiliary system

Due to physiological movement clinical MR applications for abdominal organs got off to a very slow start compared to MR imaging of other organs. However, with recent cutting-edge hardware technologies such as high performance gradient systems and phased-array capability, as well as software innovations including short TR fast spoiled gradient recalled acquisition in the steady state (GRASS), snapshot imaging such as single shot fast spin echo sequence (SSFSE) and echo planar imaging (EPI), scan times have been further reduced to make breath-hold imaging clinically viable and to enable semi-fluoroscopic, kinematic imaging recognition. The elimination of physiological motion has contributed to the significant improvement in image quality, or more specifically, the physiological motion that had long been problematic has been turned into a source of physiological information about pancreaticobiliary pathologies. In this article, the author reviewed the current status of fast MR technologies for examining pancreaticobiliary pathologies, stressing the functional and physiological aspects of the corresponding anatomy. The technologies included secretin MRCP, which became a powerful tool when combined with kinematic imaging.