Peritoneal Mesothelioma

Previous imaging reports of peritoneal mesothelioma have described a variety of radiologic appearances, but have not included its pathologic classification. We retrospectively reviewed 10 cases of peritoneal mesothelioma representing the following histologic categories: 7 epithelial, 2 sarcomatoid, and one biphasic. By imaging, epithelial mesotheliomas demonstrated diffuse thickening of the peritoneum and mesentery and/or multiple small nodules. The sarcomatoid-type appeared as a mass and the biphasic-type had radiologic and gross pathologic features of both sarcomatoid and epithelial types. We conclude that peritoneal mesothelioma presents with a wide spectrum of radiographic appearances and should therefore be included in the differential diagnoses of diffuse as well as localized peritoneal processes.

[Positron emission tomography/magnetic resonance: Present and future]

PET/MRI has recently been introduced onto the market after several years of research and development. The simple notion of combining the molecular capabilities of the PET and its difference available radiotracers with the excellent tissue resolution of the MRI and wide range of multiparametric imaging techniques has generated great expectations upon the possible uses of this technology. Many challenges must be worked out. However, the most urgent one is the derivation of the MRI-based attenuation correction map. This is especially true because the PET/CT has already demonstrated a huge clinical impact within oncology, neurology and cardiology during its short existence. Despite these difficulties, research is being carried out at a rapid pace in the clinical setting in order to find areas in which the PET/MRI is superior to other existing imaging modalities. In the few initial publications found up to date that have analyzed its clinical role, areas have been identified where PET/CT can migrate to PET/MRI, even if only to suppress the CT scan's ionizing radiation. Nonetheless, there are many theoretical applications in which the PET/MRI can further improve the field of diagnostic imaging. In this article, we will review those applications, the evidence existing regarding the MRI and PET that support those premises as well as that which we have learned in the short period of one year with our experience using the PET/MRI.

Tuberculous epididymitis associated with abdominal lymphadenopathy (2004:1b)

Although the predominant form of tuberculosis is pulmonary disease, an increasing number of cases with extra-pulmonary involvement have been reported. The diagnosis of extra-pulmonary tuberculosis is often difficult because of its protean clinical manifestations and non-specific laboratory findings. Abdominal lymph node involvement may be present alone or in combination with involvement of the gastrointestinal tract, peritoneum, and solid viscera. Tuberculous epididymitis occurs sporadically and represents a specific secondary subacute or chronic inflammatory process involving the epididymis. We present the imaging findings in a patient with tuberculous epididymitis associated with abdominal tuberculous lymphadenopathy.

Asymptomatic nonspecific serum hyperamylasemia and hyperlipasemia: spectrum of MRCP findings and clinical implications

We assessed the magnetic resonance cholangiopancreatographic (MRCP) findings in patients with asymptomatic, mild elevations of serum amylase and lipase levels to determine whether there might be a pathoanatomic cause for these laboratory abnormalities. MRCP was performed in 633 consecutive patients. Of these, 54 (8.5%) images were obtained in patients with asymptomatic serum hyperamylasemia and hyperlipasemia. MRCP was performed on a 1.0-T MR system; breath-hold gradient-recall, half-Fourier acquisition, and rapid acquisition with relaxation enhancement sequences were obtained. Findings were verified by follow-up, biopsy, or surgery. One-sided, large-sample z tests were used to compare the incidence of abnormalities between the study and control groups (579 patients). The pancreas appeared abnormal on MRCP in 31 patients (57%), including the pancreas divisum in 10 patients (18.5%). Other findings included morphologic changes compatible with chronic pancreatitis in nine patients (16.6%) and a healed pancreatic laceration, juxtapapillary duodenal diverticulum, papillary sclerosis, intraductal pancreatic lithiasis, and hemochromatosis in one patient each (1.9%). Small cystic lesions (< 1 cm) within the pancreas were seen in 15 patients (27.8%). In eight patients, these were associated with other abnormalities (pancreas divisum in three patients, chronic pancreatitis in four, and pancreatic laceration in one). No malignancy was diagnosed. The incidences of normal examination (p = 0.01), pancreas divisum (p < 0.005), and a small cystic lesion (p = 0.01) as solitary findings in this subgroup of patients were significantly higher when compared with the remainder of the studied population. Investigation of asymptomatic patients with nonspecific hyperamylasemia and hyperlipasemia by means of MRCP yielded pancreatic findings in more than 50% of these patients. Pancreas divisum was found more often than expected in the general population.

Usual and unusual causes of extrahepatic cholestasis: assessment with magnetic resonance cholangiography and fast MRI

Cholestasis may result from hepatocellular (intrahepatic) disease or biliary tract (extrahepatic) abnormalities. Etiologies causing extrahepatic cholestasis are extremely diverse and invasive procedures, such as endoscopic retrograde cholangiopancreatography (ERCP) and percutaneous transhepatic cholangiography (PTC), were previously required to establish the diagnosis. Due to refinements of magnetic resonance imaging (MRI) techniques, the patient with extrahepatic cholestasis currently can be evaluated noninvasively, and the information revealed frequently exceeds the findings obtained by ERCP and PTC. In this essay, we illustrate the classic MR cholangiographic (MRC) and MRI features of a variety of disorders causing extrahepatic cholestasis, including non-neoplastic disorders of the biliary tract (congenital abnormalities, infectious processes, iatrogenic disorders, and postsurgical complications) and neoplastic conditions (e.g., tumors of the pancreas, biliary tree, liver, ampulla, and regional lymph nodes). In most cases, familiarity with the key MRC features in addition to information obtained via cross-sectional MR images provide sufficient information for adequate lesion characterization.

Glomerulocystic kidney disease: MRI findings

Glomerulocystic kidney disease (GCKD) is a rare form of renal cystic disease characterized by cystic dilation of Bowman's capsule. The imaging findings of small renal cysts with a predominant cortical and subcapsular distribution allows for distinction from other, more common, polycystic kidney diseases. The appearance and distribution of the renal cysts by magnetic resonance imaging allow for a definitive diagnosis of GCKD.

Large retroperitoneal hibernoma in an adult male: CT imaging findings with pathologic correlation

Hibernoma is a rare benign tumor consisting primarily of brown fatty tissue. It is usually seen in locations where normal brown adipose tissue is found in fetuses and infants such as the periscapular or interscapular region, the neck, the axilla, the thorax, and, more rarely, the retroperitoneum. We report the computed tomographic findings and pathologic features of a large retroperitoneal hibernoma discovered in an adult male. Radiologists and surgeons should be aware that hibernoma should be included in the differential diagnosis of a large fatty retroperitoneal soft tissue tumor.

Focal nodular hyperplasia of the liver: detection and characterization with plain and dynamic-enhanced MRI

BACKGROUND

We compared nonenhanced and dynamic gadolinium (Gd)-enhanced magnetic resonance imaging (MRI) appearances of hepatic focal nodular hyperplasia (FNH) as depicted with breath-hold MR sequences and assessed the detectability of the individual MR sequences used.

METHODS

We retrospectively reviewed 48 consecutive patients with FNH. All patients underwent nonenhanced (T1 fast low-angle shot [FLASH] and T2 half-Fourier acquisition [HASTE]) and dynamic Gd-enhanced (T1 FLASH) MRI between December 1997 and March 2000. Individual MR sequences were analyzed separately for number of lesions, signal intensity features, dynamic enhancement pattern, and the presence and enhancement profile of a central scar. Ninety-five percent confidence intervals of absolute discrepancy were calculated to define differences in lesion detection.

RESULTS

Seventy-seven lesions were found in 48 patients. Nonenhanced FLASH imaging depicted 59 (76.6%) lesions in 45 patients. HASTE images showed 55 (71.4%) lesions in 44 patients. On T1- and T2-weighted images, lesions appeared predominantly hypointense (69.5%) and hyperintense (72.7%), respectively. Arterial and portal venous dominant phase Gd-enhanced MRI demonstrated all 77 lesions (100%), most of which showed hypervascular (94.8%), homogeneous (97.4%), and incomplete (except the central scar: 58.4%) enhancement in the arterial phase. Portal venous phase images showed lesion isointensity (50.6%) or moderate hyperintensity (46.8%) with complete enhancement (central scar: 94.8%). A central scar was detected on nonenhanced T1-weighted images (hypointense: 100%), T2-weighted images (hyperintense: 100%), arterial phase (hypointense: 59.7%) and portal venous phase (hyperintense: 71.4%) Gd-enhanced images in 78%, 69.1%, 77.9%, and 75.3% of tumors, respectively.

CONCLUSION

Arterial and portal venous phase Gd-enhanced T1-weighted sequences are superior to nonenhanced images in the detection of FNH. Typical MRI appearances include hypointensity on T1-weighted and hyperintensity on nonenhanced T2-weighted images. Most commonly, FNH shows a homogeneous (without scar) and strong enhancement during the arterial phase, with lesion isointensity or slight hyperintensity during the portal venous phase.

Hepatic veno-occlusive disease: MRI findings

We present magnetic resonance imaging findings in a patient with proven hepatic veno-occlusive disease (VOD) caused by the use of "poppers," a recreational drug used during anal intercourse. Although this report emphasizes the differential magnetic resonance imaging features between VOD and Budd-Chiari syndrome, our case is unique because the VOD was induced by unrelated substances.

Extramedullary paraspinal hematopoiesis in hereditary spherocytosis

Extramedullary hematopoiesis is a rare condition, characterized by the appearance of hematopoietic elements outside the bone marrow. It occurs primarily in patients with chronic myeloproliferative disorder or congenital hemolytic anemia. We report on a 60-year-old man with hereditary spherocytosis who presented with an extramedullary paraspinal hematopoietic mass, splenomegaly, and bone marrow expansion in the right distal femur and proximal tibia metaphysis. The diagnosis was established after biopsy of the paravertebral mass. The patient underwent a splenectomy.

Dynamic gadolinium-enhanced MR imaging of pancreatic VIPoma in a patient with Verner-Morrison syndrome

We describe a rare case of a pancreatic VIPoma diagnosed in a patient presenting with watery diarrhea, hypokalemia, and achlorhydria, the so-called WDHA or Verner-Morrison syndrome. Emphasis is placed on the dynamic gadolinium-enhanced MR profile of the tumor, characteristics which have not been illustrated previously, to the best of our knowledge.

Imaging features of pancreatic neoplasms

Pancreatic masses are common in daily imaging practice. The advent of helical CT and breathold MRI has provided a new impetus to the study of the pancreas not only for the potential of characterizing pancreatic masses and pancreatitis but also because of the more accurate staging of pancreatic neoplasms using this technique. Pancreatic tumors are classified according to its histologic origin. Ductal adenocarcinoma is the most common. Regarding ductal adenocarcinoma, despite the fast evolving imaging techniques promising an earlier diagnosis and an accurate staging, still the prognosis is extremely poor. However, new surgical data indicate that long-term survival although rare, occurs on resected tumors less than 2 cm, without vascular encasement or adenopathy. Logically, early detection and accurate staging of tumors has become the main focussing in pancreatic imaging since it may result in an increase in the survival of these patients. In this context, the role of imaging to identify, characterize and stage pancreatic neoplasms will be described. Furthermore, the key radiological features of a gamut of more uncommon pancreatic neoplasms will be illustrated. These include other exocrine epithelial tumors (anaplastic carcinoma, pancreatoblastoma, acinar cell carcinoma serous cystic pancreatic adenoma, mucinous cystic tumors, intraductal mucinous papillary tumor, and solid pseudopapillary neoplasm), endocrine tumors or islet cell tumors (insulinoma, gastrinoma, gluconoma, vipoma, non-functioning tumors), rare non-epithelial tumors (lymphoma, teratoma) and metastases to the pancreas.

Malignant focal hepatic lesions complicating underlying liver disease: dual-phase contrast-enhanced spiral CT sensitivity and specificity in orthotopic liver transplant patients

The aim of this study was to determine the accuracy of contrast-enhanced biphasic spiral CT as a screening tool in the preoperative evaluation of orthotopic liver transplant (OLT) patients. Spiral-CT examinations were performed before liver transplantation in 53 patients. Scans were retrospectively reviewed and compared with pathologic findings in fresh-sectioned livers. When findings between spiral CT and pathology were discordant, formalized livers were reexamined with lesion-by lesion evaluation. Fresh pathologic evaluation revealed 23 liver lesions (16 HCC, 7 macro-regenerative nodules). Malignancy was identified in 13 of 53 patients (24.5%). Pre-transplantation spiral CT depicted 27 liver lesions (23 HCC, 4 macro-regenerative nodules). Malignancy was suspected in 14 patients (26.4%). In 10 of 53 (18.9%), spiral CT and pathologic evaluation were discordant. Subsequent retrospective pathologic evaluation showed malignancy in 4 additional patients. Spiral CT compared with the retrospective pathologic findings revealed 36 real-negative, 14 real-positive, 0 false-positive, and 3 false-negative patients with malignancy. Sensitivity and specificity of spiral CT in detection of malignancy was 82 and 100%, respectively. Contrast-enhanced biphasic spiral CT is an accurate technique in the evaluation of patients preceding OLT. Routine fresh-sectioned liver pathologic findings are not as sensitive as previously estimated.

Pneumatosis intestinalis and portomesenteric venous gas in intestinal ischemia: correlation of CT findings with severity of ischemia and clinical outcome

OBJECTIVE

The purpose of this study was to analyze the correlation between pneumatosis or portomesenteric venous gas, or both, the severity of mural involvement, and the clinical outcome in patients with small- or large-bowel ischemia.

MATERIALS AND METHODS

CT scans of 23 consecutive patients presenting with pneumatosis or portomesenteric venous gas caused by bowel ischemia were reviewed. The presence and extent of both CT findings were compared with the clinical outcome in all patients and with the severity and extent of ischemic bowel wall damage as determined by surgery (15 patients), autopsy (three patients), or follow-up (five patients).

RESULTS

Seven patients showed isolated pneumatosis, and 16 patients showed portomesenteric venous gas with or without pneumatosis (11 and five patients, respectively). Pneumatosis and portomesenteric venous gas were associated with transmural bowel infarction in 14 (78%) of 18 patients and 13 (81%) of 16 patients, respectively. Nine patients (56%) with portomesenteric venous gas died. Of seven patients with infarction limited to one bowel segment (jejunum, ileum, or colon), only one patient (14%) died, whereas of the 10 patients with infarction of two or three bowel segments, eight patients (80%) died.

CONCLUSION

CT findings of pneumatosis intestinalis and portomesenteric venous gas due to bowel ischemia do not generally allow prediction of transmural bowel infarction, because they may be observed in patients with only partial ischemic bowel wall damage. The clinical outcome of patients with bowel ischemia with these CT findings seems to depend mainly on the severity and extent of their underlying disease.

Hepatic imaging with multidetector CT

Combining the advantages of a multirow detector array with a fast gantry rotation time, multidetector computed tomographic (CT) scanners can acquire sections at a faster rate than was previously possible. As a result, multidetector CT permits scanning during multiple specific phases of intravenous contrast enhancement and the acquisition of very thin sections over a large area, allowing the creation of multiplanar reconstructions with high z-axis resolution. The authors present an imaging strategy for the diagnosis and staging of hepatic pathologic conditions that emphasizes the role of multidetector CT. Users must master several scanning parameters to obtain the best image quality. For hepatic CT, it is practical to use relatively narrow collimation, increasing the pitch as needed to cover the entire liver. The choice of reconstruction interval is dependent on the problem for which the study is being performed. Water is recommended as an oral contrast agent for non-axial reconstructions, since high-attenuation oral contrast agents might degrade them. Appropriate scanning delays for hepatic CT are dependent on the contrast-agent injection strategy used. A triple-pass technique, highlighting the arterial, parenchymal, and portal venous phases of enhancement, is recommended.

Cystic focal liver lesions in the adult: differential CT and MR imaging features

Cystic lesions of the liver in the adult can be classified as developmental, neoplastic, inflammatory, or miscellaneous. Although in some cases it is difficult to distinguish these entities with imaging criteria alone, certain cystic focal liver lesions have classic computed tomographic (CT) and magnetic resonance (MR) imaging features, which are important for the radiologist to understand and recognize. Lesions with such features include simple (bile duct) cyst, autosomal dominant polycystic liver disease, biliary hamartoma, Caroli disease, undifferentiated (embryonal) sarcoma, biliary cystadenoma and cystadenocarcinoma, cystic subtypes of primary liver neoplasms, cystic metastases, pyogenic and amebic abscesses, intrahepatic hydatid cyst, extrapancreatic pseudocyst, and intrahepatic hematoma and biloma. Specific CT and MR imaging findings that are important to recognize are the size of the lesion; the presence and thickness of a wall; the presence of septa, calcifications, or internal nodules; the enhancement pattern; the MR cholangiographic appearance; and the signal intensity spectrum. In addition, access to critical clinical information remains extremely important. The most important clinical parameters defined include age and gender, clinical history, and symptoms. An understanding of the classic CT and MR imaging appearances of cystic focal liver lesions will allow more definitive diagnosis and shorten the diagnostic work-up.

The Swedish laparoscopic adjustable gastric banding for morbid obesity: radiologic findings in 218 patients

OBJECTIVE

The objective of this study was to determine the prevalence and radiologic features of postoperative complications after Swedish laparoscopic adjustable gastric banding surgery and to emphasize the role of the radiologist in the follow-up of those patients, especially in the treatment of complications.

MATERIALS AND METHODS

We reviewed the radiologic findings in 218 consecutive morbidly obese patients after laparoscopic placement of the Swedish gastric banding system. Radiographic studies of the stomach (obtained with liquid barium sulfate suspension) were performed before surgery and 1 month after band placement in every patient. Additional studies in symptomatic patients were performed when needed.

RESULTS

Surgical complications found included misplacement of the band (five patients, 2.3%), slippage of the band (17 patients, 7.8%), and pouch enlargement (eight patients, 3.7%). Technical problems encountered were inversion of the access port (three patients, 1.4%), leakage of the device (two patients, 0.9%), and spontaneous decrease of the stoma size caused by gastritis (seven patients, 3.2%) or the hyperosmolar properties of the IV contrast material (12 patients, 5.5%). Intrinsic abnormalities of gastroesophageal tract seen included trapping of food in the stoma (four patients, 1.8%) and esophagitis (11 patients, 5%).

CONCLUSION

Although, according to the available data, the gastric banding operation with the Swedish band meets the criteria of a low-risk laparoscopic alternative treatment of morbid obesity, the radiologic appearances of various complications may be seen on the images of patients who have undergone the procedure. The radiologist plays a key role in the early detection of those complications and treatment of specific abnormalities.

Imaging of diffuse liver disease

Advances in imaging technology and development of liver-specific contrast agents have significantly increased the role of radiology in the detection and characterization of processes diffusely involving the liver. Tailored magnetic resonance imaging (MRI) sequences allow an accurate detection of many storage and metabolic diseases, such as iron overload disorders and steatosis (fatty liver). Faster scanning techniques available with both computed tomography (CT) and MRI provide, by assessing contrast dynamics, sufficient information for the characterization of diffuse neoplastic and vascular disorders. Characteristic changes in attenuation on CT, signal intensity on MRI, and enhancing features can be used to diagnose specific diffuse diseases such as candidiasis, diffuse/multifocal hepatocellular carcinoma, and schistosomiasis. Although an overlap in imaging findings still exists, familiarity with the imaging features of uncommon disorders such as Wilson's disease, amyloidosis, and sarcoidosis may be diagnostic in the proper clinical setting. This review focuses on the current role of imaging in the detection and characterization of diffuse liver disorders. Recent developments that have amplified the role of noninvasive diagnostic evaluation of these conditions are especially highlighted.

Pancreatocolonic fistula due to severe acute pancreatitis: imaging findings

Colonic involvement is an uncommon but potentially lethal complication of severe acute pancreatitis. The spectrum of colonic complications includes localized ileus with "pseudo-obstruction", obstruction, necrosis, hemorrhage, fistula, and ischemic colitis. We report on a patient who developed pancreatocolonic fistulization in the course of protracted severe acute pancreatitis. Emphasis is made on the computed tomographic and water soluble contrast enema findings.

Magnetic resonance imaging of the exocrine pancreas

The currently available MRI, techniques that are used to perform imaging of the pancreas are reviewed. A basic pancreas examination includes: fat-suppressed breath-hold T1-weighted and respiratory triggered or breath-hold T2-weighted fast sequences The use of dynamic MRI with both extracellular gadolinium chelates and specific contrast agents is stressed in the evaluation of exocrine pancreatic diseases. It is concluded that an "all-in-one" approach including MR angiography of the pancreatic vessels and MR cholangiopancreatography of the biliopancreatic ductal system, confirmed by further studies, is presumably the most cost-effective imaging technique in the evaluation of a vast array of exocrine pancreatic diseases.

Abdominal thrombotic and ischemic manifestations of the antiphospholipid antibody syndrome: CT findings in 42 patients

PURPOSE

To determine the abdominal computed tomographic (CT) findings in patients with antiphospholipid antibody syndrome (APS).

MATERIALS AND METHODS

Retrospective review of medical records from two university medical centers from 1994 through 1997 revealed 215 patients who had a hypercoagulable state attributed to primary or secondary APS. Abdominal CT findings in these patients were reviewed for evidence of large-vessel occlusion or visceral ischemia.

RESULTS

In 42 (19.5%) of 215 patients with APS (age range, 32-65 years; mean age, 42 years), abdominal thromboses or ischemic events were detected at CT. Twenty-two (52%) had major vascular thromboses, including those in the inferior vena cava (n = 10), portal and superior mesenteric veins (n = 7), splenic vein (n = 4), and aorta (n = 1). Thirty-six (86%) patients had abdominal visceral ischemia resulting in renal infarction (n = 22), bowel ischemia (n = 13), splenic infarction (n = 6), pancreatitis (n = 3), hepatic infarction (n = 1), and/or hepatic dysfunction with portal hypertension (n = 1). In some patients, more than one abdominal organ and/or vessel was involved.

CONCLUSION

Patients who have circulating antiphospholipid antibodies are at risk for major abdominal vascular thromboses and organ infarction. Radiologists must be familiar with this syndrome; they may be the first physicians to suggest the diagnosis on the basis of findings of unusual or recurrent sites of thrombosis, especially in young patients.

Splenic and perisplenic involvement in acute pancreatitis: determination of prevalence and morphologic helical CT features

PURPOSE

The purpose of this work was to determine the prevalence and morphologic helical CT features of splenic and perisplenic involvement in patients with acute pancreatic inflammatory disease in correlation with the severity of the pancreatitis.

METHOD

One hundred fifty-nine contrast-enhanced helical CT scans of 100 consecutive patients with acute pancreatitis were reviewed retrospectively and independently by three observers. CT scans were scored using the CT severity index (CTSI): Pancreatitis was graded as mild (0-2 points), moderate (3-6 points), and severe (7-10 points). Interobserver agreement for both the CTSI and the presence of splenic and perisplenic involvement was calculated (K statistic). Correlation between the prevalence of complications and the degree of pancreatitis was estimated using the Fisher exact test.

RESULTS

The severity of pancreatitis was graded as mild (n = 59 scans), moderate (n = 82 scans), and severe (n = 18 scans). Splenic and perisplenic abnormalities detected included perisplenic inflammatory fluid collections (95 scans, 58 patients), narrowing of the splenic vein (35 scans, 25 patients), splenic vein thrombosis (31 scans, 19 patients), splenic infarction (10 scans, 7 patients), and subcapsular hemorrhage (2 scans, 2 patients). No cases of splenic artery pseudoaneurysm formation, intrasplenic venous thrombosis, intrasplenic pseudocysts, or abscesses were detected. The interobserver agreement range for scoring the degree of pancreatitis and the overall presence of abnormalities was 75.5-79.2 and 71.7-100%, respectively. A statistically significant difference between the presence of abnormalities and the severity of pancreatitis was observed (p < 0.001).

CONCLUSION

Splenic vein thrombosis (19%) and splenic infarction (7%) are relatively common CT findings in association with acute pancreatitis. The CTSI proves to be accurate in predicting these complications as there is a statistically significant correlation between the prevalence of these complications and the severity of pancreatitis.

Multicentre dose-ranging study on the efficacy of USPIO ferumoxtran-10 for liver MR imaging

AIM

A dose ranging multicentre phase-II clinical trial was conducted to evaluate the efficacy of ultrasmall superparamagnetic iron oxide (USPIO) ferumoxtran-10 for magnetic resonance (MR) imaging of focal hepatic lesions.

MATERIAL AND METHODS

Ninety-nine patients with focal liver lesions received USPIO at a dose of 0.8 (n = 35), 1.1 (n = 32), or 1.7 (n = 32) mg Fe/kg. Liver MR imaging was performed before and after USPIO with T1-weighted and T2-weighted pulse sequences. Images were analysed by two independent readers for additional information (lesion detection, exclusion, characterization and patient management). Signal intensity (SI) based quantitative measurements were also taken.

RESULTS

Post-contrast medium MR imaging showed additional information in 71/97 patients (73%) for reader one and 83/96 patients (86%) for reader two. The results with all three doses were statistically significant (P < 0.05). Signal intensity analysis revealed that all three doses increased liver SI on T1-weighted images and decreased liver SI on T2-weighted images. On T2-weighted images metastases increased in contrast relative to normal hepatic parenchyma whereas haemangiomas decreased in contrast. On T2-weighted images there was statistically improved efficacy at the intermediate dose, which did not improve at the highest dose.

CONCLUSION

Ultrasmall superparamagnetic iron oxide was an effective contrast agent for liver MR imaging at all doses and a dose of 1.1 mg Fe/kg was recommended for future clinical trials.

Characterization of focal hepatic lesions with ferumoxides-enhanced T2-weighted MR imaging

OBJECTIVE

The purpose of this study was to evaluate whether ferumoxides-enhanced MR imaging of focal hepatic lesions provides distinctive signal intensity and lesion-to-liver contrast changes for benign and malignant lesions, helping to further characterize and differentiate these lesions.

MATERIALS AND METHODS

Data analysis was performed on 70 patients, with previously identified focal hepatic lesions, who underwent MR imaging of the liver before and after IV administration of ferumoxides (10 micromol Fe/kg). Lesions analyzed with pathologically proven diagnoses included metastases (n = 40), hepatocellular carcinoma (n = 11), cholangiocarcinoma (n = 6), hemangioma (n = 4), focal nodular hyperplasia (n = 6), and hepatocellular adenoma (n = 3). Response variables measured and statistically compared included the percentage of signal-intensity change and lesion-to-liver contrast.

RESULTS

Focal nodular hyperplasia showed significant signal intensity loss on ferumoxides-enhanced T2-weighted images (mean, -43%+/-6.7%, p < 0.01). All other lesion groups showed no statistically significant change in signal intensity on ferumoxides-enhanced T2-weighted images, although signal intensity loss was seen in some individual hepatocellular adenomas (mean, -6.6%+/-24.0%) and hepatocellular carcinomas (mean, -3.3%+/-10.3%). All lesions, with the exception of hepatocellular carcinoma, had a marked increase in lesion-to-liver contrast on ferumoxides-enhanced T2-weighted images, which was statistically significant for metastases and hemangioma (p < 0.02).

CONCLUSION

Focal nodular hyperplasia shows significant decrease in signal intensity on ferumoxides-enhanced T2-weighted images, which may aid in the differentiation of focal nodular hyperplasia from other focal hepatic lesions. Other lesions, namely, hepatocellular adenoma and carcinoma, can have reticuloendothelial uptake, but usually to a lesser degree than that of focal nodular hyperplasia.

Renal and perirenal space involvement in acute pancreatitis: spiral CT findings

BACKGROUND

This study was conducted to estimate the prevalence and morphologic computed tomographic (CT) features of renal and perirenal space abnormalities in acute pancreatitis in correlation with the severity of pancreatitis.

METHODS

One hundred fifty-nine contrast-enhanced CT scans of 100 consecutive patients with acute pancreatitis were retrospectively and independently reviewed by three observers. All CT images were obtained using contrast-enhanced helical CT (collimation width = 5 mm, table increment = 7 mm/s, reconstruction interval = 5 mm, scan delay time = 30-50 s). Additional maximized images (field of view = 260 mm) of the perirenal space were available for review. All CT scans were scored with the CT Severity Score Index: pancreatitis was graded as mild (0-2 points), moderate (3-6 points), and severe (7-10 points). Interobserver agreement for both the severity score and the presence of renal and perirenal involvement was calculated. Correlation between the prevalence of complications and the degree of pancreatitis was estimated.

RESULTS

CT scans were graded as mild (n = 59), moderate (n = 82), and severe (n = 18). Abnormalities detected included perirenal stranding (n = 37 patients, 26 bilateral), perirenal fluid collections (n = 10 patients, one bilateral), ureteral encasement (n = 2 patients), renal vein thrombosis (n = 1 patient), and renal parenchymal abnormalities (n = 1 patient). The interobserver agreement range for scoring the degree of pancreatitis and the overall presence of abnormalities was 75.5-79.2% and 59.8-100%, respectively. Except for stranding of the perirenal fat, no statistically significant differences between the presence of abnormalities and the severity of pancreatitis (moderate or severe) was observed with Fisher's exact test. Also, no preferential left-sided localization of complications was observed.

CONCLUSIONS

The incidence of renal and perirenal complications from acute pancreatitis is higher than previously estimated (7%). We found no significant correlation between the prevalence of major complications and the severity of pancreatitis. These findings are important because these complications may have an impact on therapeutic strategy and can affect prognosis.

Perineal angiomyofibroblastoma: CT and MR findings with pathologic correlation

We present a case of a perineal angiomyofibroblastoma (AMFB) arising in the right perirectal fossa in a middle-aged woman, documented with CT and MRI. Compounding the rarity of the entity, this case is unique as it is the first radiological report illustrating the CT and MR features of this recently clinicopathologically described neoplasm.

Pediatric liver neoplasms: a radiologic-pathologic correlation

Only 1-2 % of all pediatric tumors occur in the liver. Two thirds of these tumors are malignant and almost all of the tumors cause clinical symptoms due to their mass effects. Besides the poor prognosis in most of the malignant tumors, for further treatment the origin and nature of the neoplasm has to be known. Due to the mostly unimpeded growth into the peritoneal cavity, the origin of the tumors is primarily often unclear and can non-invasively only be determined by advanced imaging techniques. The display of the macro- and microhistological key features of primary pediatric liver neoplasms, including hepatoblastoma (HB), infantile hemangioendothelioma (IHE), mesenchymal hamartoma (MH), undifferentiated (embryonal) sarcoma (UES), and hepatocellular carcinoma (HCC), together with their imaging representation by ultrasound, computed tomography, and magnetic resonance imaging, may deepen the understanding of the underlying pathology and its imaging appearance. Furthermore, in many cases sufficient information may be provided not only to differentiate benign from malignant tumors, but also to guide for adequate treatment.

Bilateral adrenal cystic lymphangiomas in nevoid basal cell carcinoma (Gorlin-Goltz) syndrome: US, CT, and MR findings

We present a case of bilateral adrenal cystic lymphangioma in a patient with the Gorlin-Goltz syndrome. This case is unique as it is the first illustrated case (US, CT, and MR findings) of a cystic lymphangioma arising within the adrenal gland. In addition, the coexistence of cystic adrenal lymphangioma with the Gorlin-Goltz syndrome has not been described previously.

New formula for quantification of pleural effusions from computed tomography

The authors develop a method to accurately and easily estimate the volume of pleural effusions with computed tomography (CT). In 15 patients with either simple or loculated pleural effusions (14 right-sided and 11 left-sided), routine helical CT examinations of the thorax were obtained. Two experienced radiologists visually estimated the volume of the effusions. Three-dimensional reconstructions of the pleural effusions were performed from the helical CT examinations, and the volumes of the effusions were calculated. Effusion volumes were also estimated using the formula d2 x l (d = greatest depth of the effusion on a single CT image, l = greatest length of the effusion). The computer calculated the estimated volumes and they were then statistically compared. The coefficient of correlation between the estimation by measurement and calculated volumes of all effusions was 0.908 (p<0.0001) for the right side, and 0.849 for the left side (p<0.002). Excluding the loculated effusions, the coefficient of correlation was 0.969 for the right side and 0.949 for the left side (p<.001). The volume estimation by visual inspection was also correlated to the calculated volumes (0.84 on the left and 0.85 on the right, p<0.008), but resulted in a consistent overestimation by 300 ml to 500 ml. Although pleural effusion volumes can be estimated by visual inspection with good correlation, some overestimation is consistently seen. Use of the formula d2 x l readily enables estimation of pleural effusion volume from CT, from two simple measurements. This formula-based method of volume estimation provides an accurate and easily measured means of estimation that is readily obtained from routine CT of the chest.

Image mottle in abdominal CT

RATIONALE AND OBJECTIVES

To investigate image mottle in conventional CT images of the abdomen as a function of radiographic technique factors and patient size.

METHODS

Water-filled phantoms simulating the abdomens of adult (32 cm in diameter) and pediatric (16 cm in diameter) patients were used to investigate image mottle in CT as a function of x-ray tube potential and mAs. CT images from 39 consecutive patients with noncontrast liver scans and 49 patients with iodine contrast scans were analyzed retrospectively. Measurements were made of the mean liver parenchyma Hounsfield unit value and the corresponding image mottle.

RESULTS

For a given water phantom and x-ray tube potential, image mottle was proportional to the mAs-0.5. Increasing the phantom diameter from 16 cm (pediatric) to 32 cm increased the mottle by a factor of 2.4, and increasing the x-ray tube potential from 80 kVp to 140 kVp reduced the mottle by a factor of 2.5. All patients were scanned at 120 kVp, with no correlation between patient size and the x-ray tube mAs. The mean mottle level was 7.8 +/- 2.2 and 10.0 +/- 2.5 for the noncontrast and contrast studies, respectively. An increase in patient diameter of 3 cm would require approximately 65% more mAs to maintain the same level of image mottle.

CONCLUSIONS

The mottle in abdominal CT images may be controlled by adjusting radiographic technique factors, which should be adjusted to take into account the size of the patient undergoing the examination.

Fibrolamellar carcinoma of the liver: radiologic-pathologic correlation

Fibrolamellar carcinoma is a malignant hepatocellular tumor with distinct clinical and pathologic differences from hepatocellular carcinoma. It differs from hepatocellular carcinoma in demographics, condition of the affected liver, tumor markers, and prognosis. Fibrolamellar carcinoma characteristically manifests as a large hepatic mass in adolescents or young adults (without gender predominance). Cirrhosis; elevated alpha-fetoprotein levels; and typical risk factors for hepatocellular carcinoma such as viral hepatitis, alcohol abuse, and metabolic disease are typically absent. Fibrolamellar carcinoma is characterized pathologically by cords of tumor cells surrounded by abundant collagenous fibrous tissue arranged in a parallel or lamellar distribution. Fibrotic lamellae often coalesce to form a central scar. Fibrolamellar carcinoma characteristically appears on radiologic images as a lobulated heterogeneous mass with a central scar in an otherwise normal liver. Radiologic evidence of cirrhosis, vascular invasion, or multifocal disease--findings typical of hepatocellular carcinoma--is uncommon in fibrolamellar carcinoma. Imaging features of fibrolamellar carcinoma overlap with those of other scar-producing lesions including focal nodular hyperplasia (FNH), hepatocellular adenoma and carcinoma, hemangioma, metastases, and cholangiocarcinoma. FNH, in particular, may simulate fibrolamellar carcinoma, since both have similar demographic and clinical characteristics. Because some believe that radiologic diagnosis of FNH is possible, it is important to understand the imaging appearance of fibrolamellar carcinoma to avoid misdiagnosing this malignant tumor as a FNH.

Safety profile of ultrasmall superparamagnetic iron oxide ferumoxtran-10: phase II clinical trial data

The safety data from the phase II clinical trial of ferumoxtran-10, an ultrasmall superparamagnetic iron oxide contrast agent, are presented. One hundred and four patients with focal liver or spleen pathologies underwent ferumoxtran-10-enhanced magnetic resonance (MR) imaging at doses of 0.8, 1.1, and 1.7 mg Fe/kg. Overall, 15% patients reported a total of 33 adverse events, regardless of causality. The adverse events most frequently seen were dyspnea (3.8%), chest pain (2.9%), and rash (2.9%). No serious adverse events were reported during the 48 hour observation period. There were no clinically significant effects on vital signs, physical examination, and laboratory results. Ferumoxtran-10 is a safe and well tolerated MR contrast agent.

MRI in focal liver disease: a comparison of small and ultra-small superparamagnetic iron oxide as hepatic contrast agents

The purpose of this study was to compare small and ultrasmall superparamagnetic iron oxide particles (SPIO and USPIO, respectively) as MR contrast agents for the evaluation of focal hepatic disease. In two different patient groups (SPIO [n = 53], USPIO [n = 27]), with focal liver disease (metastases, hepatocellular carcinoma [HCC], hepatocellular adenoma [HCA], and focal nodular hyperplasia [FNH]), spin-echo T1- and T2-weighted images (T1WI, T2WI) were obtained at 1.0T, before and after intravenous contrast administration. The percentage signal-to-noise ratio (SNR) change and lesion-to-liver contrast (LLC) were measured and statistically compared. The liver decreased in signal intensity (SI) after SPIO administration (-28%) and increased after USPIO administration (+16%) on T1WI. On T2WI, the liver decreased in SI on postcontrast images with both agents (-78% SPIO, -73% USPIO). This difference was not statistically significantly different (P < or = .07). Both SPIO and USPIO provided >500% improvement in LLC on T2WI. On T1WI, LLC was increased in metastases (120%) and HCC (325%) with SPIO. Post-USPIO, LLC was increased on T1WI only in metastases (>500%). Both SPIO and USPIO show excellent hepatic uptake, presumed secondary to reticuloendothelial activity, based on the degree of %SI change seen in the liver after administration of contrast on T2WI. However, USPIO preparations exhibit blood pool activity that may aid in further characterization of focal liver lesions, as is evidenced by their greater T1 effect in the liver and in some focal liver lesions.

Dynamic gadolinium-enhanced MR findings in infantile hepatic hemangioendothelioma

We report a case of a 2 1/2-year-old girl presenting with abdominal pain, fever, vomiting, and hepatomegaly. In spite of the unusual age at presentation, dynamic gadolinium-enhanced MR findings, which have not been previously illustrated, proved to be highly specific for the diagnosis of infantile hepatic hemangioendothelioma because of the characteristic enhancement pattern.

Three-dimensional volumetric assessment of abnormally low attenuation of the lung from routine helical CT: inspiratory and expiratory quantification

OBJECTIVE

The purpose of this investigation was to quantitatively assess abnormally low attenuation of the lung by use of three-dimensional volumetric reconstructions from routine helical CT and to assess their correlation with pulmonary function tests.

MATERIALS AND METHODS

Helical CT was performed in 100 patients in full inspiration. Examination was also performed in full expiration in 53 of these patients. Three-dimensional volumetric reconstructions were performed for total lung volumes at inspiration and at expiration, with a threshold of -896 H on inspiratory CT and -790 H on expiratory CT, to quantify emphysematous change. Correlation was made with pulmonary function tests in 79 patients.

RESULTS

CT volumetric assessments of abnormally low attenuation of the lung at inspiration and expiration had a high correlation (r2 = .84, p < or = .0001). In comparison with pulmonary function tests, both inspiratory low attenuation of the lung and expiratory low attenuation of the lung correlated well with the logarithm of the ratio of the forced expiratory volume in 1 sec (FEV1) to the forced vital capacity (r2 = .74, p < or = .0001 and r2 = .74, p < or = .0001, respectively) and with the percentage of predicted ratio of the FEV1 to the forced vital capacity (r2 = .69, p < or = .0001 and r2 = .69, p < or = .0001, respectively). Linear correlations were also seen with FEV1, residual volume, and forced residual capacity.

CONCLUSION

Three-dimensional volumetric reconstructions of hypoattenuating lung correlate well with pulmonary function tests. In addition, inspiratory and expiratory data are also correlative, suggesting that a dedicated expiratory examination is not needed. This easily obtainable information will prove useful for patients with obstructive lung disease from emphysema, providing a measure of pulmonary function status in this population.

The Rocky liver: radiologic-pathologic correlation of calcified hepatic masses

Although relatively uncommon in daily clinical practice, calcification may be found in inflammatory hepatic lesions and in benign and malignant liver neoplasms. The most common source of calcified hepatic lesions is inflammatory conditions such as granulomatous diseases (e.g., tuberculosis). The calcification typically involves the entire lesion and appears as a dense mass that can produce artifacts on computed tomographic (CT) scans. Echinococcus cysts have curvilinear or ring calcification. Hemangiomas, especially large ones, may contain large, coarse calcifications that are centrally located in areas of fibrosis; these may be seen at CT (20% of cases) or radiography (10%). In hepatocellular adenoma, calcifications may be solitary or multiple and are usually located eccentrically within a complex heterogeneous mass. Calcifications in fibrolamellar carcinoma have been reported in 15%-25% of cases at CT and occur in a wide variety of patterns. Calcifications in intrahepatic cholangiocarcinoma are typically accompanied by a desmoplastic reaction and are visible at CT in about 18% of cases. Calcified hepatic metastases are most frequently associated with mucin-producing neoplasms such as colon carcinoma. Knowledge of the pathologic features of each entity helps radiologists to better recognize the shape, size, density, number, location, and distribution of hepatic calcifications seen on images and to narrow the differential diagnosis.

Improved technique for pancreatic MRI: value of oblique fat suppression imaging with oral barium administration

PURPOSE

Our goal was to determine the efficacy of a dedicated protocol for pancreatic MRI using fat suppression, oblique plane orientation, and barium as an oral contrast agent.

METHOD

Fifty-two patients were enrolled in our study. In each patient, the stomach and duodenum were opacified with 300 ml oral barium. In all patients conventional SE T1- and T2-weighted images and fat-suppressed axial and oblique T1-weighted images of the upper abdomen and the pancreas, respectively, were obtained. The different T1-weighted sequences were compared for visualization of the pancreas and for lesion conspicuity. Oblique images were obtained in a plane parallel to the overall axis of the pancreas. All sequences were qualitatively assessed by two independent blinded readers and statistically compared.

RESULTS

The combination of fat suppression and oblique imaging significantly improved the visualization of the different anatomic portions of the normal pancreas as well as pathologic findings in the pancreas in 70-92% of the cases compared with conventional axial T1-weighted imaging (p < 0.001) and in 52-75% of the cases compared with axial fat-suppressed T1-weighted imaging (p < 0.001), respectively. Increased image noise and blurring artifacts resulted in slight image degradation after Gd-DTPA administration. Barium as a duodenal contrast agent was beneficial for delineation of the pancreatic head from the adjacent bowel structures.

CONCLUSION

In pancreatic imaging, fat-suppressed T1-weighted imaging is superior to conventional T1-weighted imaging, and oblique imaging is superior to axial imaging. Intravenous Gd-DTPA administration was useful only in selected cases.

MRI of the rectum: non-neoplastic disease

The rectum has become the most successful area of the gastrointestinal tract to be studied with MRI. Its anatomical location, fixed in the pelvic fat, and its lack of peristalsis, make it an ideal organ to be scanned with MRI. In addition, MRI allows a direct sagittal and coronal display, of key importance to colorectal surgeons whose terminology and approach are based on the coronal plane. The sagittal plane allows the depiction of the relation of the rectum to the sacrum, uterus and prostate, with detail not available by other imaging techniques, and the use of endorectal coils allows excellent demonstration of the rectal wall. Although MRI has been used primarily to study rectal carcinoma, other diseases, congenital, inflammatory and vascular in origin, can be studied using the correct technique.

Hepatic calcification

Although a specific diagnosis of the calcified liver mass may not always be possible, there are some morphologic imaging features that help to indicate the diagnosis (Table 1). The radiologist needs to be aware of the wide spectrum of diseases of the liver that can calcify, and the most common causes. Pathologic correlation with axial imaging has greatly enhanced our understanding and interpretation of the underlying liver lesion, which may help to differentiate benign from malignant etiology.

Hepatic metastases

Developments in ultrasound, CT scan, and MR imaging have increased our ability to detect and characterize focal liver lesions. Advances in the medical and surgical treatment of secondary liver tumors have continued to challenge these advances in radiology. A successful outcome depends on knowledge of the size and location of the tumor burden, and accurate radiologic assessment is crucial to identify those subgroups who may benefit from surgery and to prevent unnecessary radical surgery in those likely to gain only a short-term benefit.

Benign lesions of the liver

Although many hepatic lesions can overlap significantly in their imaging appearance, an imaging approach that is based upon identifying the pathologic and functional components of a lesion can aid in distinction from other entities. In this manner, the diagnostic evaluation can be tailored using the appropriate imaging modality for the lesion at hand. An understanding of the benign liver lesions based on the cellular line of origin and subsequent functional components aids in grasping their expected imaging appearance and may aid in their distinction from malignant tumors. Thus, an imaging approach leading to diagnosis of these tumors should be based on this underlying knowledge of the functional components and cells within the lesion to be studied. For lesions with Kupffer's cell activity, such as FNA, Tc-99m sulfur colloid scan or MR imaging with SPIO may yield the most diagnostic information. For lesions such as hepatic cysts or angiomyolipoma, the diagnosis is usually not a dilemma. For hemangiomas, the most commonly encountered benign hepatic lesion, distinction from other entities may be readily apparent from the initial CT scan or US examination, or it may require additional evaluation with MR imaging. Finally, for other lesions with many cellular components, such as HCA, the imaging findings may not be specific enough by any modality to preclude tissue diagnosis. In any case, it is important to know the diagnostic accuracy and limitations of the imaging modalities available for assessment of any given benign hepatic mass.