The Atlanta Classification of acute pancreatitis revisited.

BACKGROUND: In a complex disease such as acute pancreatitis, correct terminology and clear definitions are important. The clinically based Atlanta Classification was formulated in 1992, but in recent years it has been increasingly criticized. No formal evaluation of the use of the Atlanta definitions in the literature has ever been performed. METHODS: A Medline literature search sought studies published after 1993. Guidelines, review articles and their cross-references were reviewed to assess whether the Atlanta or alternative definitions were used. RESULTS: A total of 447 articles was assessed, including 12 guidelines and 82 reviews. Alternative definitions of predicted severity of acute pancreatitis, actual severity and organ failure were used in more than half of the studies. There was a large variation in the interpretation of the Atlanta definitions of local complications, especially relating to the content of peripancreatic collections. CONCLUSION: The Atlanta definitions for acute pancreatitis are often used inappropriately, and alternative definitions are frequently applied. Such lack of consensus illustrates the need for a revision of the Atlanta Classification.

Significance of hyperattenuating and contrast-enhancing hepatic nodules detected in the cirrhotic liver during arterial phase helical CT in pre-liver transplant patients: radiologic-histopathologic correlation of explanted livers.

BACKGROUND: Hyperattenuating nodules detected by arterial phase helical computed tomography (HCT) in patients with cirrhosis usually are believed to represent hepatocellular carcinomas (HCCs). We correlated HCT morphology of hyperattenuating hepatic nodules detected during arterial phase scans with the histopathology of explanted livers of patients with hepatic cirrhosis undergoing liver transplantation. METHODS: Three hundred fifty-four patients had arterial and portal phase HCT performed before subsequent hepatic transplantation. Each patient received 180 mL of contrast by power injection at 5 mL/s. All hyperattenuating nodules detected on arterial phase HCT were assessed for morphology and evidence for contrast enhancement. Explanted livers in all patients were then sectioned at 10-mm intervals, and the histology of the nodules was correlated with the HCT findings. RESULTS: Sixty-one hyperattenuating nodules were detected on the arterial phase HCT in 43 patients: 41 nodules were benign regenerating nodules (RN), three were dysplastic nodules (DP), and 17 were HCCs. Most RN/DP nodules were 5-20 mm in diameter, had distinct margins, were homogeneous, and were isoattenuating on precontrast, portal, and delayed scans. Thirty-six showed positive contrast enhancement and displayed a wide range of attenuation profiles. HCC nodules were 6-50 mm. All showed positive contrast enhancement and displayed a wide range of attenuation profiles. CONCLUSION: Hyperattenuating nodules seen on arterial phase HCT are likely to be RN/DP nodules. In many cases, it is not possible to distinguish between RN/DP and HCC. Thus, clinical decisions regarding inclusion criteria for transplantation based on CT morphology of liver lesions may be tenuous.

Pancreatic carcinoma: imaging update 2001.

This paper discusses the most recent advances in imaging of pancreatic carcinomas. The specific modalities discussed include helical computed tomography (HCT) with combined CT angiography, magnetic resonance imaging (MRI) and magnetic resonance cholangiopancreatography (MRCP), and positron emission tomography (PET). Endoscopic ultrasound is discussed in other papers. HCT is believed to be the most efficacious modality for initial detection and staging of pancreatic carcinomas. It has an accuracy rate of about 95-97% for the detection of carcinomas and of virtually 100% for staging unresectable carcinomas. The accuracy for CT staging of a resectable tumor is about 80-85%, with small surface metastases to liver and peritoneum being the most often missed findings. MRI and MRCP are best used for evaluation of patients that cannot receive intravenous contrast media for HCT and of patients who have equivocal HCT findings. PET imaging may be useful for detection of extrapancreatic nodal metastases.

Safety and efficacy of mangafodipir trisodium (MnDPDP) injection for hepatic MRI in adults: results of the U.S. multicenter phase III clinical trials (safety).

The short-term safety of mangafodipir trisodium (MnDPDP) injection was studied in 546 adults with known or suspected focal liver lesions. An initial contrast-enhanced computed tomography examination was followed by unenhanced magnetic resonance imaging (MRI), injection of MnDPDP (5 micromol/kg), and enhanced MRI. Adverse events were reported for 23% of the patients; most were mild to moderate in intensity, did not require treatment, and were not drug related. The most commonly reported adverse events were nausea (7%) and headache (4%). The incidence of serious adverse events was low (nine events in six patients) and not drug related. Injection-associated discomfort was reported for 69% of the patients, and the most commonly reported discomforts included heat (49%) and flushing (33%). Changes in laboratory values and vital signs were generally transient, were not clinically significant, and did not require treatment. There were no clinically significant short-term risks from exposure to MnDPDP.

Pancreaticoduodenal arcades and dorsal pancreatic artery: comparison of CT angiography with three-dimensional volume rendering, maximum intensity projection, and shaded-surface display.

OBJECTIVE: The objective of this study was to compare the ability of CT angiography to depict the pancreaticoduodenal arcades and the dorsal pancreatic artery using the techniques of three-dimensional (3D) volume rendering, maximum intensity projection (MIP), and shaded-surface display (SSD). SUBJECTS AND METHODS: Twenty-seven patients were selected at random from a group of 42 patients undergoing arterial-phase helical CT angiography before liver transplantation. CT angiograms were constructed from identical data sets using 3D volume rendering, MIP, and SSD. RESULTS: Seventy-two vessels were evaluated in 27 patients. Three-dimensional volume rendering depicted 24 anterior and 22 posterior arcades and 26 dorsal pancreatic arteries; combined MIP and SSD depicted 14 anterior and 13 posterior arcades and 19 dorsal pancreatic arteries. Thirty vessels with diameters of between 2 and 3 mm were well seen with 3D volume rendering but were incompletely depicted with MIP and SSD. Sixteen vessels with diameters of greater than 3 mm were well seen using all three techniques. Twenty-six vessels with diameters of less than 2 mm were faintly seen with 3D volume rendering but were unidentifiable with MIP and SSD. CONCLUSION: Three-dimensional volume rendering is superior to MIP and SSD in the depiction of pancreaticoduodenal arcades and dorsal pancreatic arteries. Unlike the other rendering techniques, 3D volume rendering can also show relationships between these vessels and pancreatic parenchyma and adjacent structures.

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.

Computed tomography in the diagnosis and staging of cholangiocarcinoma and pancreatic carcinoma.

This paper is a review of the current techniques and results of helical CT in the diagnosis and staging of pancreatic adenocarcinoma and cholangiocarcinoma of the intra and extrahepatic biliary ducts. CT has a diagnostic accuracy rate of over 95% for detection and diagnosis of pancreatic carcinoma and close to 100% in staging unresectable tumors. The accuracy of staging surgically resectable tumors is about 80%. Accuracy of determining the level of biliary obstruction caused by cholangiocarcinoma is close to 100%. The accuracy of making a specific diagnosis is about 78%.

Impact of double helical CT and three-dimensional CT arteriography on surgical planning for hepatic transplantation.

BACKGROUND: To assess the impact of preliver transplant double helical computed tomography (DHCT) and three-dimensional computed tomography arteriography (3D-CTA) on surgical planning for hepatic transplantation. METHODS: Vascular findings detected on DHCT/3D-CTAs of 80 patients were shown to the transplant surgeon in a blinded fashion. These findings included hepatic arterial anatomy, diameters of the major vessels that supplied the liver, celiac axis stenosis, splenic artery (SA) aneurysms, and portal vein thrombosis (PVT). The surgeon was asked to state the "planned" surgical approach for each case based on scan findings. These results were subsequently compared with what "actually" occurred at transplantation by review of surgical records. RESULTS: Fifty-five patients had conventional and 25 patients had nonconventional hepatic arterial anatomy. Three patients had PVT, three patients had celiac axis stenosis, and three patients had SA aneurysms. Correlation between the "actual surgical technique" and the "planned surgical approach" was seen in 50/55 (91%) patients with conventional and in 23/25 (92%) patients with nonconventional anatomy. Five patients requiring aortohepatic interposition grafts for arterial anastomoses had either severe celiac axis stenoses or arterial inflow vessels that were 3 mm or smaller. Three patients with PVT underwent successful surgical resection of the thrombosed segment and standard PV anastomoses as planned. Patients with complete replacement of hepatic arterial supply to the superior mesenteric artery required alteration of the sequence of the vascular anastomoses. Patients with SA aneurysms had surgical ligation of the splenic artery. CONCLUSIONS: DHCT/3D-CTA provides noninvasive means to identify findings that have significant impact on surgical planning for hepatic transplantation including celiac axis stenosis, diameter of inflow arterial vessel

Hepatic and portal surface veins: a new anatomic variant revealed during abdominal CT.

OBJECTIVE: The objective of this paper is to describe a new finding on CT of hepatic and portal vein segments located in a subcapsular location on the surface of the liver. SUBJECTS AND METHODS: From a series of more than 11,000 contrast-enhanced abdominal CT scans performed from 1993 to 1997, 14 patients were identified as having hepatic or portal vein segments or both in a subcapsular location on the surface of the liver. RESULTS: We found seven portal vein surface segments in seven patients and 14 hepatic vein surface segments in 12 patients. Of the 14 patients, five had both portal and hepatic vein surface segments. Therefore, in a cohort that exceeded 11,000 patients, the incidence of this finding was 0.1%. Four patients had cirrhosis, two had small hypervascular liver lesions, and eight had healthy livers. The surface veins were not associated with any other recognized vascular anomalies or with anastomoses to extrahepatic systemic veins. CONCLUSION: Hepatic and portal veins can course to a subcapsular location on the surface of the liver. This anatomy is believed to be a normal variant and can be found in patients with healthy livers and normal hepatic vein hemodynamics and in patients with portal hypertension.

Pancreatic arterial anatomy: depiction with dual-phase helical CT.

PURPOSE: To determine the efficacy of arterial phase helical computed tomography (CT) for the depiction of small pancreatic arteries. MATERIALS AND METHODS: Arterial phase helical CT (3-mm collimation, 1-mm reconstruction interval) was performed during power injection of 180 mL of ioversol at 5 mL/sec. Two radiologists reviewed 100 consecutive arterial phase helical CT scans of the pancreas in patients with normal glands and recorded the frequency of visualization of the major visceral (celiac, hepatic, splenic, gastroduodenal, superior mesenteric) and small pancreatic (dorsal pancreatic, right branch of the dorsal pancreatic, pancreaticomagna, caudal pancreatic, transverse pancreatic, anterior and posterior arcade, and inferior pancreaticoduodenal) arteries. RESULTS: Scans in 87 patients were technically satisfactory and were included in the analysis. The major visceral arteries were seen in all patients. The following secondary pancreatic arteries were seen: dorsal pancreatic, 82 (94%) patients; pancreaticomagna, 45 (52%); caudal pancreatic, 34 (39%); transverse pancreatic, 36 (41%); right branch of the dorsal pancreatic, eight (9%); anterior arcade, 47 (54%); posterior arcade, 63 (72%); and inferior pancreaticoduodenal, 73 (84%). CONCLUSION: Small pancreatic arteries can be delineated on arterial phase helical CT scans by using optimized techniques.

Percutaneous CT-guided catheter drainage of infected acute necrotizing pancreatitis: techniques and results.

OBJECTIVE: The objective of this paper was to assess the safety and efficacy of percutaneous catheter drainage for initial treatment of infected acute necrotizing pancreatitis. MATERIALS AND METHODS: Thirty-four patients with acute necrotizing pancreatitis shown with contrast-enhanced CT were treated for sepsis with percutaneous catheter drainage. Extent of necrosis was less than 30% in 10 cases, 30-50% in 10 cases, and greater than 50% in 14 cases. Fourteen patients had central necrosis. Eighteen patients were critically ill with multiorgan failure. RESULTS: Sixteen (47%) of the 34 patients were cured with only percutaneous catheter drainage, including four (29%) of the 14 patients with central gland necrosis and 12 (60%) of the 20 with body-tail necrosis. Sepsis was controlled (defervescence of fever and return of WBC to normal) in an additional nine patients, allowing elective pancreatic surgery for control of pancreatic duct fistula. Eight patients failed to show clinical improvement after drainage and required necrosectomy. No patient experienced catheter-related complications. Mortality was 12% (all four deaths occurred after necrosectomy because of multiorgan failure). CONCLUSION: Percutaneous catheter drainage is a safe and effective technique for treating infected acute necrotizing pancreatitis. Overall, sepsis was controlled in 74% of patients, permitting elective surgery for treatment of pancreatic fistula, and 47% of patients were cured with no surgery required. No catheter-related complications occurred.

Triphasic helical CT of hepatic focal nodular hyperplasia: incidence of atypical findings.

OBJECTIVE: The objective of this paper is to assess the findings of focal nodular hyperplasia of the liver as depicted by triphasic helical CT. MATERIALS AND METHODS: Triphasic helical CT scans (arterial, portal vein, and delayed phase scans) in 12 patients with hepatic focal nodular hyperplasia were reviewed to assess the frequency of findings on each phase. The final diagnosis of focal nodular hyperplasia was proven by surgery or biopsy in eight cases and by additional imaging studies and clinical follow-up in four cases. RESULTS: Only two of the 12 patients had CT features that could be considered typical of focal nodular hyperplasia. The other patients had one or more findings considered to be atypical and more suggestive of a primary or metastatic hypervascular malignant hepatic neoplasm, such as an enhancing capsule, lack of a central scar, early draining veins, rapid washout of contrast material on the portal vein phase or persistent enhancement on the delayed phase, and interim growth. CONCLUSION: Although classic or typical triphasic helical CT manifestations of focal nodular hyperplasia do occur, atypical features are common and can mimic those of primary or metastatic hypervascular hepatic neoplasms. In these latter cases, additional imaging studies, such as a 99mTc-sulfur colloid liver scan, an MR scan, or a percutaneous biopsy, are essential for correct diagnosis.

Helical computed tomography of the liver: techniques, applications and pitfalls.

Helical computed tomography (CT) of the liver has greatly improved both the accuracy and characterization of focal liver masses. This paper focuses on specific techniques for helical CT, including dual helical CT (acquisition of scans during both the arterial and portal venous phases of contrast enhancement), high-dose helical CT, delayed iodine CT, and helical CT angiography and portography. Techniques of generating three-dimensional helical CT angiograms from axial datasets are also discussed here. The clinical applications and results of these different techniques will also be discussed. In addition, helical CT produces or reveals some specific hepatic perfusion abnormalities that can lead to erroneous diagnoses; caveats for avoiding these pitfalls in interpretation are offered.

Cavernous hemangiomas of the liver: enlargement over time.

OBJECTIVE: It has been reported that cavernous hemangiomas of the liver either do not enlarge over time, or, of the very few lesions that have shown an increase in diameter on follow-up imaging studies, the increase has been minimal. The objective of this paper is to report growth of four cavernous hemangiomas that were shown to have doubled to tripled in diameter on follow-up imaging studies done between 34 months and 10.5 years after the initial diagnosis. CONCLUSION: This report indicates that hepatic hemangiomas can grow significantly in diameter, although such growth is unusual. Despite the growth of the lesion, however, if the imaging features are characteristic of hemangioma an imaging diagnosis can still be made confidently.

Upper gastrointestinal tract and abdomen: water as an orally administered contrast agent for helical CT.

PURPOSE: To evaluate the use of orally administered water as a negative contrast agent and intravenously administered glucagon in helical computed tomography (CT) of the upper abdomen. MATERIALS AND METHODS: Ninety-eight adult patients underwent 102 helical CT examinations. Patients received 700 mL of water orally 30 minutes before and another 350 mL of water orally with 1 mg of glucagon intravenously just before CT. The amount of water actually ingested was recorded. Luminal distention at five sites was graded on a three-point scale; depiction of six normal anatomic structures was evaluated. RESULTS: Luminal distention improved with the amount of water ingested in four of the five sites (P < .03 in three sites). Depiction of all six normal anatomic structures improved with increasing luminal distention (P < .001). The normal duodenal papilla was seen in 42% (83 of 198) of the examinations. Of 87 patients who had previously undergone CT with positive oral contrast agents, 89% (n = 77) preferred the water, 11% (n = 10) had no preference, and none preferred the positive agent (P < .001). Upper gastrointestinal tract abnormalities were easily recognized and depicted. CONCLUSION: Water is an efficacious negative contrast agent for evaluation of the upper gastrointestinal tract during helical CT.

Transcatheter arterial embolization of two symptomatic giant cavernous hemangiomas of the liver.

Cavernous hemangiomas are usually asymptomatic; however, a small percentage may cause symptoms. This case report discusses palliation by transcatheter arterial embolization with polyvinyl alcohol particles.

CT angiography of the visceral vessels.

CT angiography (CTA) is a promising new technique for vascular imaging. This review focuses first on the technique necessary for successful scanning of the visceral vessels. As in many new modalities, there are different protocols for scanning and rendering of images. The relative strengths and weaknesses of these different approaches are discussed. A discussion of the applications of CTA to depict normal and abnormal anatomy of the visceral vessels follows. These applications include celiac stenosis, splenic artery aneurysms, evaluation for hepatic arterial anatomy before liver transplantation, visceral arterial anatomy in pancreaticoduodenal surgery, the superior mesenteric artery in intestinal ischemia, vascular encasement in patients with pancreatic neoplasms, and, finally, the hepatic vessels before hepatic tumor resection.

MR angiography of the portal venous system.

MR angiography (MRA) has become an increasingly important and practical clinical tool for the noninvasive assessment of abdominal vessels. Both two-dimensional time-of-flight and phase contrast techniques allow accurate evaluation of the portal venous system. This article reviews these two MRA techniques and discusses their impact on the diagnosis of vascular abnormalities of the portal venous system.

MR angiography of the peripheral vasculature.

MR angiography (MRA) for the evaluation of peripheral arterial occlusive disease is a rapidly evolving technique. Recent prospective clinical trials have indicated that MRA may play an important role in the evaluation of patients with peripheral arterial disease. This article discusses the pertinent technical aspects and limitations of peripheral MRA as well as some of the clinical data available.