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.

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 </= 3 mm, complete replacement of hepatic arterial supply, PVT, and SA aneurysms.

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.

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.

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.

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.

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.

Imaging of complications in liver transplantation

Hepatic transplantations are being performed with increasing frequency, leading to greater demand for accurate evaluation of related complications. Ultrasonography (US) is the primary screening technique for detection of vascular complications of hepatic transplantation: angiography is used to confirm the US findings or when the US study is suboptimal. Hepatic artery thrombosis, the most common (as high as 42% of pediatric cases; 4%-12% of adult cases) and important vascular complication, may be associated with bilomas, infarcts, or abscesses at gray-scale US and absence of proper hepatic and intrahepatic arterial flow at Doppler analysis. Hepatic artery stenosis (seen in 11% of cases) is suspected if a focal accelerated velocity of greater than 2-3 m/sec with turbulence is seen at or distal to the stenosis or if a tardus parvus pattern of intrahepatic arterial flow is seen. In cases of inferior vena cava thrombosis and stenosis, US may show echogenic thrombus or obvious narrowing, with a substantially increased flow velocity through the stenosis or reversal of flow in the hepatic veins. Biliary complications occur relatively often (13%-25% of cases) after liver transplantation; bile leakage and biliary stricture, the most common biliary complications, are seen as a fluid collection and a stricture, respectively. Although acute rejection is one of the most serious complications affecting graft survival, it cannot be reliably detected with available diagnostic tests or radiologic methods.

[Utility of bolus dynamic CT for the detection of hypervascular malignant hepatic tumors: mainly referring to the comparison with delayed phase contrast-enhanced CT]

In order to analyze the usefulness of dynamic contrast-enhanced CT, 84 patients who had hepatocellular carcinoma or suspected hypervascular metastases were studied with conventional incremental dynamic CT (CID-CT) or double helical CT (DH-CT). Delayed phase contrast-enhanced CT studies were consecutively performed in all patients. Thirty-six of 84 patients had malignant hepatic neoplasms; six had hepatocellular carcinoma and 30 had metastatic tumors. At first, the detectability of hepatic lesions was evaluated with bolus dynamic CT and delayed phase CT. Dynamic CT has detected more lesions than delayed CT. Some hepatic lesions described as isodensity were missed on CID-CT. Therefore, delayed phase CT cannot be eliminated when CID-CT is performed. Secondly, hepatic lesion detectability with CID-CT was compared with that of DH-CT. DH-CT did not miss the hepatic lesions picked up by delayed phase CT and was expected to provide excellent detectability of hypervascular hepatic neoplasms. In addition, first helical CT showed most hepatic lesions as areas of obvious hyperdensity, while CID-CT did not show their correct vascularities. So-called hypervascular hepatic tumors, however, were not always hypervascular and were demonstrated as areas of iso-hypodensity even on initial helical scanning. Second helical CT was useful to detect these so-called hypervascular, but actually hypovascular lesions. In conclusion, dynamic CT was helpful in detecting hypervascular hepatic malignant neoplasms, and DH-CT was more accurate than CID-CT for the detection of hepatic lesions and the evaluation of vascular lesion.

Hepatic helical CT: effect of reduction of iodine dose of intravenous contrast material on hepatic contrast enhancement

PURPOSE

To evaluate the effect of a reduction in iodine dose by altering volume and/or concentration of contrast material on hepatic contrast enhancement (HCE) values during hepatic helical computed tomography (CT).

MATERIALS AND METHODS

One hundred eleven patients were randomized into four contrast material protocols according to concentration (in milligrams of iodine per milliliter)/volume (in milliliters)/grams of iodine: group 1, ioversol, 320/150/48; group 2, ioversol, 320/100/32; group 3, iohexol, 300/150/45; group 4, ioversol, 300/100/30. Helical CT protocols were identical for the four groups. Time-attenuation curves were constructed; the mean HCE, contrast enhancement index (CEI), and optimal liver scanning interval (OLSI) were calculated; and the results were compared statistically. RESULTS;: Time-attenuation curves, mean HCE, CEI, and OLSI of groups 1 and 3 were significantly superior to those for groups 2 and 4. Decrease in volume from 150 to 100 mliters decreased mean HCE by 27%, CEI by 69%, and OLSI from 80%-100% to 0%-43% at threshold levels of 40-60 HU.

CONCLUSION

Decrease in iodine dose from 45-48 g to 30-32 g significantly decreases all HCE values, which potentially decreases detection of focal hypovascular hepatic lesions.

Hepatic MR imaging with ferumoxides: a multicenter clinical trial of the safety and efficacy in the detection of focal hepatic lesions

PURPOSE

To assess the safety and diagnostic efficacy of intravenous ferumoxides, a superparamagnetic iron oxide, for depiction of focal hepatic lesions on magnetic resonance (MR) images.

MATERIALS AND METHODS

This open-label study included 208 patients with known or suspected focal hepatic lesions. MR images were obtained before and 45 minutes to 4 hours after intravenous infusion of ferumoxides (10 mumol/kg). The effect of ferumoxides on signal intensity of the liver was assessed with quantitative analysis. Safety was evaluated with patient monitoring and laboratory measurements.

RESULTS

Mean lesion-to-liver contrast-to-noise ratio on T2-weighted images was 9.1 on unenhanced images and 12.7 on enhanced images. Signal intensity of normal liver on enhanced images decreased to 37% of that on unenhanced images. In blinded image evaluations, additional lesions were identified on 27% of enhanced images. No serious adverse events occurred.

CONCLUSION

Ferumoxides is a safe and efficacious contrast agent for the detection of focal liver lesions on T2-weighted images.

Hepatic arterial anatomy: demonstration of normal supply and vascular variants with three-dimensional CT angiography

Three-dimensional (3D) helical computed tomographic (CT) angiography is a promising method of determining vascular anatomy. This technique is useful in delineating the arterial anatomy of the liver, demonstrating the normal anatomy and vascular variants in a highly visual fashion. The "typical" hepatic arterial anatomy occurs in only 55% of the population, and numerous variants exist; the standard classification system for hepatic arterial anatomy includes 10 variations. After helical scanning, postprocessing with reconstruction algorithms such as shaded surface display and maximum-intensity projection provides highly graphic, easily understandable views of vascular anatomy. The 3D CT angiograms, with their global view of the anatomy and inherent advantage of volumetric rotation of the vascular system, are useful to surgeons and others with limited experience in interpreting axial anatomy. Determination of hepatic arterial anatomy with 3D CT angiography has already been shown to be clinically useful in patients being evaluated for liver transplantation.

Carcinoma of the head of the pancreas: evaluation of the pancreaticoduodenal veins with dynamic CT--potential for improved accuracy in staging

PURPOSE

To determine if detection of abnormal dilatation of pancreaticoduodenal veins can improve the accuracy of computed tomographic (CT) staging of pancreatic adenocarcinoma.

MATERIALS AND METHODS

CT scans obtained during bolus administration of contrast material in 86 patients (aged 34-85 years) with pancreatic head carcinoma were reviewed. The diameter of the small veins that surround the head of the pancreas was measured (normal diameter of gastrocolic trunk, < or = 7 mm; of anterior superior pancreaticoduodenal vein, < or = 4 mm; of posterior superior pancreaticoduodenal vein, < or = 4 mm).

RESULTS

Twenty-nine abnormally dilated peripancreatic veins were identified in 22 patients. Twenty-two of these dilated veins were in 16 patients with other CT criteria of tumor unresectability; seven dilated veins were in six patients with tumors deemed resectable at CT. All tumors in these latter six patients were unresectable at surgery.

CONCLUSION

Although dilatation of these small peripancreatic veins without other CT criteria of tumor unresectability is an unusual finding, it may be a reliable sign of unresectable pancreatic carcinoma.

Evaluation of a non-breath-hold MR cholangiography technique

PURPOSE

To evaluate prospectively a non-breath-hold magnetic resonance (MR) cholangiographic technique.

MATERIALS AND METHODS

Twenty-nine non-breath-hold, heavily T2-weighted, turbo spin-echo MR cholangiograms were obtained in 28 patients and compared with 28 direct cholangiographic studies in 24 patients.

RESULTS

MR cholangiography showed the intrahepatic ducts (IHDs) within the peripheral third of the liver and within the four hepatic segments in 100% of cases with dilated ducts. IHDs were seen in the peripheral third in 82% of cases with nondilated ducts and within the four hepatic segments in 91%. The extrahepatic duct (EHD), dilated and nondilated, was visualized in 90% of cases. Filling defects were identified in the EHD in 71% of cases and in the gallbladder in 100%. All obstructions were identified and their site and character accurately shown in most cases. The presence of IHD dilatation was accurately shown, and estimates of EHD and main pancreatic duct caliber correlated closely with those of direct cholangiography.

CONCLUSION

Non-breath-hold MR cholangiography is a reliable method for depiction of the biliary system.

Hepatic arterial anatomy in transplantation candidates: evaluation with three-dimensional CT arteriography

PURPOSE

To assess the utility of three-dimensional (3D) hepatic helical computed tomographic (CT) arteriography as a replacement for conventional angiography in the evaluation of the arterial anatomy of patients being considered for liver transplantation.

MATERIALS AND METHODS

Three-dimensional CT arteriograms were obtained in 115 patients. Seventeen patients also underwent conventional angiography, and 16 patients who did not undergo angiography underwent hepatic transplantation.

RESULTS

Among the 3D CT arteriograms, 106 delineated the major arteries that supplied the liver. Nine were considered technical failures. In the 17 patients with angiographic correlation, there was only one marked disagreement with 3D CT arteriography. In the 16 patients with surgical correlation, no marked discrepancies were found.

CONCLUSION

In transplantation candidates, successful 3D CT arteriography was as accurate as angiography in the assessment of hepatic arterial anatomy. It was also safer, more convenient, and more easily tolerated. Conventional CT plus 3D CT arteriography was only 25% as expensive as the cost of conventional CT and conventional angiography.

Evaluation of the portal venous system before liver transplantation: value of phase-contrast MR angiography

OBJECTIVE

The purpose of this study was to assess the accuracy of phase-contrast MR angiography with gadolinium in evaluating the patency and blood flow direction of the portal venous system; the presence, extent, and type of varices; and the patency of surgical decompressive shunts in patients before liver transplantation. This information is essential in management and care of patients with chronic liver disease and portal hypertension and those who are candidates for liver transplantation.

SUBJECTS AND METHODS

Twenty-four patients with portal venous hypertension were evaluated with phase-contrast MR angiography. Two patients had surgical splenorenal shunts and one had a mesocaval shunt. Phase-contrast angiograms were acquired as a series of two-dimensional sequential coronal sections during breath-holding and after IV administration of gadopentetate dimeglumine. Correlative findings from color flow Doppler sonography, contrast-enhanced CT scanning, and conventional angiography were available in 23, 20, and 10 patients, respectively, and were used as standards. The images from each technique were analyzed independently for patency of and flow direction in the portal vein, splenic vein, superior mesenteric vein, and surgically created shunts, and for detection, distribution, and extent of five variceal groups.

RESULTS

Findings from phase-contrast MR angiography completely agreed with those of sonography, CT scanning, and conventional angiography. The main portal vein was patent in 18 patients, stenosed in one, partially thrombosed in one, and occluded in four. Phase-contrast MR angiography correctly showed hepatofugal flow in three patients and hepatopetal flow in 17 patients. Both the splenic and superior mesenteric veins were patent in 20, partially thrombosed in one, and occluded in three cases. Phase-contrast MR angiograms showed 85% of the variceal groups, and MR rating of variceal size was not significantly different from that of CT rating. Phase-contrast MR angiography correctly showed the patency of all three surgical decompressive shunts.

CONCLUSION

Phase-contrast MR angiography is accurate for evaluating the patency and flow direction of the portal venous system, detecting and determining the distribution and extent of varices, and assessing the patency of surgically created shunts. Therefore, it is a reliable and noninvasive technique that can provide crucial information in the preoperative workup of liver transplant recipients.

Cross-sectional imaging of the pancreas

CT is the primary modality for the evaluation of patients with pancreatic disease. A number of pitfalls can occur in interpretation of the scans, but most can be avoided by using state-of-the-art scanners and dynamic contrast enhancement techniques and by recognizing normal anatomic variants. However, in other cases, CT may show only nonspecific findings and a correct diagnosis can be reached only by utilization of additional imaging techniques or guided FNAB.

Helical CT during arterial portography: optimization of contrast enhancement and scanning parameters

PURPOSE

To determine the optimal scanning parameters for helical computed tomography during arterial portography (CTAP) of the liver.

MATERIALS AND METHODS

Single- and double-helix CTAP were performed in 11 and 20 adult patients, respectively, with 200 mL of contrast material (300 mg of iodine per milliliter) injected at a rate of 3 mL/sec via the superior mesenteric artery. Scanning delays were adjusted for single-helix CTAP so the last scan was obtained at 66 seconds. Delays were adjusted for double-helix CTAP so the last scan during the first helix (CTAP-1) was obtained 10 seconds before the end of the injection at 56 seconds and the first scan during the second helix (CTAP-2) was obtained at the end of the injection at 66 seconds.

RESULTS

Single-helix CTAP scans were of poor quality owing to multiple perfusion abnormalities. Lesion detection for double-helix CTAP-1 was 93.2% and was 100% for CTAP-2, and CTAP-2 scans had significantly fewer perfusion abnormalities.

CONCLUSION

A scanning delay of 60-66 seconds appears to be optimal. The CTAP-1 scans showed no useful information and need not be acquired.

Imaging and intervention in acute pancreatitis

An International Symposium was held in Atlanta in 1992 to present the state of the art of diagnostic evaluation and management of acute pancreatitis and to agree on an acceptable series of clinical definitions for classifying the disease and its complications. The symposium was composed of 40 internationally recognized experts in pancreatic disease from 15 countries representing six disciplines (anatomy, gastroenterology, internal medicine, pathology, radiology, and surgery). The purpose of this article is to present the radiologically relevant aspects of the symposium; to define the state of the art of imaging and intervention in acute pancreatitis, particularly how and when to use computed tomography and how and when to perform percutaneous therapy versus surgery; and to encourage radiologists to use precise and proper nomenclature when describing the morphologic manifestations of acute pancreatitis as depicted by various imaging modalities.

Phase-contrast MR angiography of the portal venous system: preoperative findings in liver transplant recipients

Sequential two-dimensional phase-contrast MR angiography can be used to accurately evaluate the anatomy, patency, and flow direction of the portal venous system and the presence, extent, and distribution of portosystemic collaterals. Its large field of view, insensitivity to the patient's body habitus, and graphic display format make this MR technique extremely useful for preoperative evaluation of patients with chronic liver disease and portal hypertension. This pictorial essay illustrates the spectrum of abnormalities seen on phase-contrast MR angiography of the portal venous system in patients with endstage liver diseases and portal hypertension.

Early advanced hepatocellular carcinoma: evaluation of CT and MR appearance with pathologic correlation

PURPOSE

To determine the computed tomographic (CT) and magnetic resonance (MR) imaging appearances of early advanced hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Twenty-seven surgically resected cases of early advanced HCC were studied with CT, CT during arterial portography, CT arteriography, and MR imaging.

RESULTS

The sensitivity of standard CT (unenhanced, early, and late CT combined) for the detection of early advanced HCC was 81%, while that of standard MR imaging (T1- and T2-weighted MR imaging combined) was 83%. A nodule-in-nodule appearance was identified in approximately one-third to one-half of cases. Signal behavior of early and advanced components of early advanced HCC followed the expected behaviors of isolated early HCC and isolated advanced HCC, respectively. Tumor size was accurately estimated with standard CT and standard MR imaging.

CONCLUSION

More research must be performed to ascertain whether any relationship exists between the different types of HCC and the clinical outcome.

Utility of magnetization prepared GRE MRI for the detection of focal liver lesions

We compared the efficacy of rapidly acquired magnetization prepared gradient-echo (MP-GRE) sequences with CT and standard MRI pulse sequences for the detection of focal liver lesions. Fourteen patients with 28 focal liver lesions were scanned. TI times of 300, 450, and 600 ms were used. MP-GRE lesion conspicuity was compared to corresponding CT, T1, T2, T2-post-superparamagnetic-iron-oxide (SPIO), and STIR images. It was found that the differences between MP-GRE and CT and MP-GRE and T1 MRI were not significant. However, overall anatomic detail was better with CT and T1 MRI than MP-GRE. Lesion conspicuity was significantly worse with the MP-GRE than with the T2, T2-post-SPIO, and STIR sequences (all p values = 0.00). Maximal liver signal nulling occurred at TI = 300 ms in 13 out of 14 patients. However, the T1 for optimal focal liver lesion conspicuity varied widely and could not be predicted before scanning. No new lesions were seen on the MP-GRE sequence that could not be seen on the CT or standard MRI sequences. As currently implemented, MP-GRE imaging offers no advantage in the detection of focal liver lesions over CT and standard MRI pulse sequences.

Radiologic staging of pancreatic adenocarcinoma

Dynamic CT currently is the imaging modality of choice for staging of pancreatic carcinoma. It has an accuracy of 72% in predicting tumor resectability and an accuracy of virtually 100% in predicting tumor unresectability. However, it is important that the CT criteria of unresectability be defined for each individual institution. In some hospitals, extended pancreatectomy, including resection of involved major extrapancreatic vessels, contiguous solid or hollow organs, and regional lymph nodes, is performed for pancreatic carcinoma. Thus, these CT findings would not be considered to obviate surgical resection, whereas in other hospitals, surgeons consider tumor spread beyond the gland, particularly vascular involvement, as a contraindication for resection. It is also important to note that enlarged regional lymph nodes that would be included in the resection are not considered to be a CT criteria of unresectability when they occur as an isolated finding. MR imaging, EUS, and angiography have less significant roles compared with CT in the staging of pancreatic carcinoma; however, MR imaging and EUS can be valuable staging techniques in patients in whom an optimal dynamic contrast-enhanced CT cannot be obtained, although angiography now is indicated primarily to provide the surgeon with a vascular roadmap prior to resection or to evaluate patients in whom CT is equivocal.

MR imaging with i.v. superparamagnetic iron oxide: efficacy in the detection of focal hepatic lesions

OBJECTIVE

The purpose of this study was to evaluate the efficacy of superparmagnetic iron oxide (SPIO) in the detection of focal hepatic lesions on MR images.

SUBJECTS AND METHODS

The study included 21 patients with 115 focal hepatic lesions and eight patients without focal hepatic lesions. T1- and T2-weighted MR images were obtained at 1.5 T before and 60 min after the end of injection of an SPIO agent. Contrast-enhanced CT scans were obtained in all patients within 10 days after MR imaging. The effect of SPIO on the signal intensity of the liver and spleen was assessed by using quantitative analysis of the region of interest. Efficacy was evaluated by using multiple criteria and unenhanced and SPIO-enhanced images. Evaluations included subjective assessment of image quality, counting the number of lesions detected, and statistical analysis of quantitative changes in the signal intensity of lesions and of normal liver.

RESULTS

By all criteria, SPIO-enhanced T2-weighted MR images were superior to unenhanced T2-weighted images and to contrast-enhanced CT scans. Conversely, by all criteria, SPIO-enhanced T1-weighted MR images were worse than unenhanced T1-weighted images and contrast-enhanced CT scans. The mean lesion-to-liver contrast on T2-weighted images was 317% on unenhanced images and 1745% on SPIO-enhanced images. For T1-weighted, the mean contrast was 26% on unenhanced images and 18% on SPIO-enhanced images.

CONCLUSION

SPIO is an efficacious contrast agent for the detection of focal hepatic lesions when T2-weighted MR images are used.

CT of hypervascular hepatic tumors: are unenhanced scans necessary for diagnosis?

OBJECTIVE

In most institutions, a combination of unenhanced and contrast-enhanced CT is used to screen patients for suspected hypervascular hepatic neoplasms. Elimination of the unenhanced examination could save time and expense and reduce the patient's exposure to radiation. We compared unenhanced and incremental bolus dynamic contrast-enhanced CT for detection of hypervascular hepatic neoplasms and evaluated the need for preliminary unenhanced hepatic CT.

SUBJECTS AND METHODS

We prospectively examined 101 consecutive patients with hypervascular primary hepatic malignant tumors or suspected hypervascular metastases. Primary hepatic neoplasms included hepatocellular carcinoma (seven), sarcoma (two), and hemangioendothelioma (one); extrahepatic primary tumors included breast (37) and renal cell (24) carcinoma, melanoma (15), carcinoid (nine), and endocrine and other tumors (six). All patients had both unenhanced and bolus dynamic contrast-enhanced CT with 5-mm collimated sections at 8-mm intervals. For contrast-enhanced CT, 150-180 ml of IV contrast material, a mechanical power injector, and a scanning protocol that allowed completion of liver imaging within 2 min were used. Both unenhanced and contrast-enhanced CT scans were compared for detection and conspicuousness of hepatic lesions.

RESULTS

Hepatic lesions were found in 34 patients. In 21 patients, all hepatic lesions seen on unenhanced scans also were apparent on contrast-enhanced scans. However, in 12 (57%) of 21 patients, lesions were more conspicuous and better defined on contrast-enhanced scans. The absolute number of lesions detected with each method of scanning differed in 12 patients. In four patients, the contrast-enhanced scan showed more lesions; in five patients, the unenhanced scan showed more lesions; and in three patients, administration of contrast material obscured some lesions shown on unenhanced scans and made others more conspicuous. If only a contrast-enhanced CT scan had been obtained, the presence of malignant hepatic neoplasm would have been missed in only one case (a patient with a single 2.8-cm metastasis from renal cell carcinoma).

CONCLUSION

Bolus dynamic contrast-enhanced CT alone correctly showed the presence or absence of primary or metastatic hypervascular hepatic tumors in 100 of 101 cases. If the goal of CT examination is detection of hypervascular hepatic lesions, use of contrast-enhanced CT alone may be adequate and the addition of unenhanced scans is not cost-effective.

Incremental dynamic bolus computed tomography of acute pancreatitis

Acute pancreatitis represents a wide spectrum of inflammatory disease involving the pancreas, peripancreatic tissues, adjacent solid organs, gastrointestinal and biliary tract, and vascular system. The extent and severity of the inflammatory process determines the prognosis of the patient and the need for specific surgical, endoscopic, and radiologically-guided intervention. Computed tomography is the single best imaging test for evaluating patients with acute pancreatitis. It can accurately stage the inflammatory process and can identify associated complications that require careful observation or immediate intervention. It also is essential for guiding percutaneous catheter placement for treatment of infected and noninfected fluid collections.

Diagnosis and staging of pancreatic adenocarcinoma with dynamic computed tomography

We assessed the accuracy of dynamic contrast-enhanced computed tomography (CT) in the diagnosis and staging of 213 patients with pancreatic carcinoma and compared it with the accuracy of angiography and surgery. A correct CT diagnosis of pancreatic carcinoma was made in 207 of 213 (97%) patients. Tumors were located in the pancreatic head in 64%, the body in 22%, and the tail in 10%, and enlarged the pancreas diffusely in 4%. CT staged 25 (12%) patients as having potentially resectable tumors and 188 (88%) as having unresectable tumors on the basis of local extension (72%), contiguous organ invasion (43%), vascular invasion (82%), and distant metastases (50%). Compared with angiography in 60 patients, CT detected vascular invasion missed on angiography in 20%, and angiography detected invasion missed by CT in 5%. In these latter cases, other CT criteria of unresectability were present, and angiography provided no significant staging information. Compared with surgery in 71 patients, CT accurately predicted unresectable tumors in 100% of patients and resectable tumors in 72% of patients. Eleven of the patients with CT-resectable tumors underwent resection. Median survival was 22.7 months, with four patients alive at a median of 15.5 months postoperatively. Palliative resections were performed in six patients, and median survival was 14.4 months.

Venous anatomy of the pancreatic head: normal CT appearance in cadavers and patients

OBJECTIVE

This study was conducted to define the normal CT appearance of the four pancreaticoduodenal veins (anterior and posterior superior, and anterior and posterior inferior) in the head of the pancreas in injected cadaveric specimens and to assess the frequency with which these normal vessels are seen on dynamic contrast-enhanced CT scans.

MATERIALS AND METHODS

The appearance of the four pancreaticoduodenal veins was studied on CT scans of four cadavers in which the portal veins were injected in situ with radiopaque solutions. A computer-generated three-dimensional model of the pancreatic head and its venous drainage was then produced from one cadaveric examination to show the venous anatomy. After definition of the venous anatomy in the cadaveric specimen, the anterior superior pancreaticoduodenal vein, posterior superior pancreaticoduodenal vein, and gastrocolic trunk were analyzed retrospectively on dynamic bolus contrast-enhanced abdominal CT scans of 100 consecutive patients who had no evidence of pancreatic disease.

RESULTS

The anterior and posterior superior pancreaticoduodenal veins were seen on 98% and 88% of scans, respectively. The veins had mean diameters of 2.1 mm. The gastrocolic trunk was seen on 89% of scans and had a mean diameter of 4.7 mm. The inferior pancreaticoduodenal veins are small and were not identified definitively.

CONCLUSION

The anterior and posterior superior pancreaticoduodenal veins and gastrocolic trunk are routinely visualized on CT scans of patients without pancreatic disease. Consequently, assessment of the veins may be useful in staging pancreatic carcinoma.

Percutaneous management of pancreatic fluid collections

Percutaneous catheter drainage of both infected and non-infected pancreatic fluid collections is a safe, efficacious procedure. The results of this procedure depend upon proper selection of patients based upon their clinical status as well as the morphological findings depicted by computed tomography and endoscopic retrograde cholangiopancreatography, careful preprocedural planning and execution of the drainage procedure, good catheter care with follow-up imaging and contrast studies, and attention to the criteria of catheter removal. An average success rate of 80% should be expected with a complication rate of about 15%.

Radiology of the pancreas

The techniques and applications of pancreatic imaging and interventional pancreatic radiology continued to expand in 1991. The most notable progress was the use of MR imaging for evaluation of the pancreas, particularly the investigation of contrast agents to produce enhancement of the pancreatic parenchyma. These agents offer considerable promise for the future of pancreatic MR imaging. The use of CT for detection and evaluation of complications of pancreatitis continued to grow and new investigations appeared that attempted to define the role of surgery vis-à-vis percutaneous and endoscopic interventional techniques. Finally, further understanding of cystic pancreatic neoplasms developed as the result of new investigations.

Pancreaticoenteric fistula: no longer a surgical disease?

We report our experience with eight patients with severe persistent pancreatitis associated with peripancreatic fluid collections requiring placement of drainage catheters who subsequently developed pancreatic fistula. The fistulas were diagnosed by endoscopic retrograde cholangiopancreatography, contrast tube study, or Hypaque enema at a mean of 13 weeks after diagnosis of pancreatitis and drain placement. These fistulas involved the duodenum in five patients and colon in three patients. Six patients had fistula resolution with medical therapy (after removal of percutaneous drainage catheters in three and with drain removal in conjunction with transpapillary stenting of a disrupted pancreatic duct in another three). We conclude that in patients with ongoing pancreatitis, pancreaticoenteric fistulas are probably caused by erosion of percutaneous drainage catheters. Such fistulas resolved with conservative treatment in six of eight patients.

Hepatocellular carcinoma: reduced frequency of typical findings with dynamic contrast-enhanced CT in a non-Asian population

Four computed tomographic (CT) findings have been described as typical or diagnostic of hepatocellular carcinoma: Primary morphologic findings include tumor encapsulation and fatty metamorphosis and secondary findings include venous invasion and arterioportal shunting. However, virtually all of the articles reporting these findings with significant frequency have been from Japan and thus represent an almost purely Asian population. The authors analyzed a series of 93 patients with hepatocellular carcinoma, only eight of whom were Asian. With the exception of venous invasion (48%), the analysis showed that while the four CT features may be typical of hepatocellular carcinoma, three features occurred with low frequency in a non-Asian population: tumor encapsulation, 12%; fatty metamorphosis, 0%; and arterioportal shunting, 4%. In addition, a review of the literature showed that all of the findings have occurred in other hepatic neoplasms, including benign and metastatic tumors.

Root of the superior mesenteric artery in pancreatitis and pancreatic carcinoma: evaluation with CT

To determine if changes involving the root of the superior mesenteric artery are specific for neoplasm, the authors retrospectively reviewed 173 computed tomographic (CT) examinations of patients with proved pancreatitis (103 examinations) and pancreatic ductal adenocarcinoma (70 examinations). Streaky infiltration of the fat surrounding the root was seen in 27 of 56 examinations of acute pancreatitis, in four of 24 examinations of chronic pancreatitis, in 12 of 23 examinations of pancreatitis complicated by abscess, and in 25 of 70 examinations of pancreatic carcinoma. Periarterial lymph nodes were visible in 14 with acute pancreatitis, in three with chronic pancreatitis, in six with pancreatic abscess, and in 11 with pancreatic carcinoma. A focal mass extended to within 1 cm of the root in 10 with acute pancreatitis, in two with chronic pancreatitis, in four with pancreatic abscess, and in 24 with pancreatic carcinoma; the mass obliterated the periarterial fat in seven with acute pancreatitis, in one with pancreatic abscess, and in 18 with pancreatic carcinoma. Circumferential encasement occurred in one with chronic pancreatitis, in four with pancreatic abscess, in 14 with pancreatic carcinoma, and in none with acute pancreatitis; nearly all cases of encasement revealed loss of periarterial fat. Thus, these indicators are not specific for neoplasm.