Cystic masses of the spleen: radiologic-pathologic correlation

Many focal splenic lesions may appear to be cystic at cross-sectional imaging. In this article, the following types of cystic splenic masses are discussed: congenital (true cyst), inflammatory (abscesses, hydatid cyst), vascular (infarction, peliosis), posttraumatic (hematoma, false cyst), and neoplastic (hemangioma, lymphangioma, lymphoma, metastasis). The key findings at ultrasound, computed tomography, and magnetic resonance imaging can be correlated with underlying gross and microscopic pathologic findings. Although tissue sampling is still required in many cases to yield a definitive diagnosis, recognition and understanding of the spectrum of imaging and pathologic features of these lesions often help narrow the differential diagnosis.

Diagnosis of renal artery stenosis: feasibility of combining MR angiography, MR renography, and gadopentetate-based measurements of glomerular filtration rate

OBJECTIVE

Our aim was to evaluate the feasibility of combining in a single test (1) structural evaluation of renal arteries with MR angiography, (2) functional evaluation of global glomerular filtration rates calculated on the basis of plasma disappearance of gadopentetate dimeglumine, and (3) renographic analysis of individual kidneys based on the dynamic changes in signal intensity that occur after administration of gadopentetate dimeglumine.

SUBJECTS AND METHODS

We used unenhanced MR angiography to measure patency of the renal arteries in 10 healthy volunteers and in 10 patients with renal artery stenosis. Calculations of global glomerular filtration rate were based on measurements of plasma disappearance of gadopentetate dimeglumine as shown by MR relaxometry. For renography with gadopentetate dimeglumine, we generated curves that showed changes in signal intensity in both kidneys over time; intrarenal kinetics were studied by measuring the time of arrival of gadopentetate dimeglumine in the cortex and outer medulla of the kidney. Conventional angiograms, measurements of global glomerular filtration rate based on plasma disappearance of 99mTc-DTPA, and 99mTc-DTPA renograms were used as reference standards. We compared the two different methods of determining global glomerular filtration rates by computing the correlation coefficient of the linear regression of rates derived from studies with gadopentetate dimeglumine versus rates derived from studies with 99mTc-DTPA.

RESULTS

In all volunteers, renal arteries were well visualized, and global glomerular filtration rates based on plasma clearance of gadopentetate dimeglumine were normal. In nine of 10 patients, correlation was good between findings on MR angiograms and findings on conventional arteriograms. Finding were discordant in one patient because the patient moved during the MR angiography. For all six patients studied, correlation was good between measurements of global glomerular filtration rates based on plasma clearance of gadopentetate dimeglumine and those based on clearance of 99mTc-DTPA (r = 98%).

CONCLUSION

Our results suggest the potential of magnetic resonance for a comprehensive approach for detection of renal artery stenosis. This novel approach provides structural evaluation of renal arteries with unenhanced MR angiography. MR renography is done and global glomerular filtration rates are determined by using MR relaxometry after injection of contrast material. Corticomedullary transit times can be determined on the basis of the dynamic changes in signal intensity that occur after administration of gadopentetate dimeglumine.

MR demonstration of a cystic pheochromocytoma

Cystic pheochromocytoma is a rare tumor of the adrenal gland that can pose a diagnostic challenge. We report a case of a 14-year-old boy who had an adrenal lesion that appeared cystic by both sonography and CT, but that demonstrated hemorrhage into the lesion at MR imaging, and proved to be a cystic pheochromocytoma. We emphasize the importance of considering the diagnosis of pheochromocytoma when faced with a cystic lesion of the adrenal gland.

Islet cell tumors of the pancreas: pathologic-imaging correlation among size, necrosis and cysts, calcification, malignant behavior, and functional status

OBJECTIVE

The purpose of our study was to correlate the imaging and pathologic features of islet cell tumors with regard to tumor size, necrosis and cysts, calcification, malignant behavior, and functional status.

MATERIALS AND METHODS

We retrospectively reviewed the clinical, pathologic, and imaging features of all 133 cases of pathologically proved islet cell tumors of the pancreas seen at the Armed Forces Institute of Pathology. Clinical data, including the patients' symptoms and serologic characteristics, were used to distinguish hyperfunctioning tumors (those causing symptoms related to elevated serum polypeptide levels) from nonhyperfunctioning tumors; hyperfunctioning tumors were divided further into insulin-producing and non-insulin-producing types. All patients had at least one cross-sectional imaging study, including CT (n = 118), sonography (n = 42), or MR imaging (n = 22). Clinical, pathologic, and imaging features were evaluated and correlated with tumor size, necrosis and cysts, calcification, local invasion, vascular invasion, metastases, and functional status.

RESULTS

Islet cell tumors with areas of necrosis or cystic change found pathologically and on imaging studies (56/133) were larger (8.4 cm in mean transverse diameter) than homogeneous solid lesions (2.9 cm in mean transverse diameter) and were predominantly non-insulin producing (48/56) and nonhyperfunctioning (36/56). Of the 43 insulinomas, 35 were small (2.2 cm in mean transverse diameter), solid, and homogeneous. Larger size also was associated with calcification and malignant behavior, including local invasion, vascular invasion, and distant metastases.

CONCLUSION

Our findings show that cystic and necrotic islet cell tumors are usually non-insulin-producing and nonhyperfunctioning neoplasms and larger than the typically solid and small insulinomas. Calcification, local invasion, vascular invasion, and metastatic disease are more commonly seen with larger neoplasms.

Iliopsoas compartment: normal anatomy and pathologic processes

The iliopsoas compartment is an extraperitoneal space that contains the greater psoas, smaller psoas, and iliac muscles. Many pathologic processes may involve the iliopsoas compartment, including inflammatory, hemorrhagic, and neoplastic conditions. Psoas muscle infection is usually due to direct extension from contiguous structures. With the decreasing incidence of tuberculosis, the majority of psoas abscesses now encountered have a pyogenic origin. Hemorrhage into the psoas muscle can be spontaneous or secondary to various conditions. Neoplastic involvement of the psoas muscle is usually due to contiguous spread and is rarely primary. With the refinement of imaging modalities, there has been increased recognition of diseases that involve the iliopsoas compartment. Although these conditions may look similar radiologically, they can be correctly diagnosed by combining the radiologic findings with the clinical history. Biopsy is effective in diagnosis of such conditions; aspiration and drainage are effective in both diagnosis and therapy.

Biliary cystadenoma and cystadenocarcinoma: clinical-imaging-pathologic correlations with emphasis on the importance of ovarian stroma

PURPOSE

To evaluate cross-sectional imaging in the distinction of biliary cystadenoma from cystadenocarcinoma and in the determination of the presence of ovarian stroma.

MATERIALS AND METHODS

In 34 patients, radiologic studies and specimen photographs and descriptions were reviewed retrospectively without knowledge of the patient group. Histologic features were reviewed without knowledge of the radiologic findings and analyzed for epithelial and stromal components. Correlation was made between the radiologic findings, gross morphologic features, internal fluid characteristics, and histologic features.

RESULTS

The 34 patients had 27 biliary cystadenomas, 22 with ovarian stroma, and seven cystadenocarcinomas, four with ovarian stroma. Gross morphologic and imaging features suggestive of biliary cystadenocarcinoma included internal septation and nodularity. Septation without nodularity was seen only in biliary cystadenoma. Nonbilious fluid was the only feature associated with the presence of ovarian stroma but was not distinguishable on images.

CONCLUSION

Imaging studies accurately reflect the nodularity and septation seen grossly to distinguish biliary cystadenoma and cystadenocarcinoma but do not allow distinction of the presence or absence of ovarian stroma.

Comparison of ultrasound, CT, and MR imaging in the evaluation of candidates for TIPS

To compare ultrasound (US), CT, and MRI in the evaluation of hepatic vascular anatomy, portal and splenic venous flow, and collateral pathways (varices and spontaneous shunts) in candidates for transjugular intrahepatic portosystemic shunting (TIPS), 17 patients with history of refractory variceal bleeding or intractable ascites underwent duplex US, contrast-enhanced CT, and MRI before TIPS. The appearance of portal and hepatic anatomy was graded from 1 (not visible) to 4 (excellent visualization) independently by four radiologists. Presence and direction of portal and splenic venous flow, and presence and location of varices and spontaneous portosystemic shunts were also assessed. Results and effects of interobserver variation were assessed for significance using Friedman's ANOVA and Wilcoxon's signed-rank test. MRI yielded higher scores than CT or US for hepatic veins (P < .0001) and inferior vena cava (P < .0001). MRI and CT scored better than US for portal vein branches (P = .012) and splenic vein (P = .0038). All tests demonstrated the main portal vein well, with no statistically significant difference. US and MRI were more sensitive than CT for detecting portal vein flow and direction (US 76%, CT 0%, MRI 82%). MRI was most sensitive for splenic vein flow and direction (US 41%, CT 0%, MRI 76%). CT and MRI were more sensitive than US in detecting varices (US 5%, CT 50%, MRI 58%) and spontaneous shunts (US 13%, CT 75%, MRI 75%). Interobserver variation did not influence results significantly P = .3691). MRI provides the most useful information and may be the preferred single imaging test prior to TIPS.

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.

Fluoxetine hydrochloride (Prozac)-induced pulmonary disease

We describe a patient who developed progressive dyspnea, lung infiltrates, and restrictive lung disease in association with the antidepressant fluoxetine hydrochloride (Prozac). The pathologic findings were consistent with hypersensitivity pneumonitis. An associated pulmonary phospholipidosis was also noted.

MR imaging of the spleen

MR imaging is used in the spleen primarily to supplement CT scan studies. Because of its multiplanar capabilities and potential characterization of lesions on the basis of signal features, however, MR can provide important diagnostic information. This article reviews appropriate imaging techniques and the MR appearance of congenital anomalies, trauma, inflammatory and vascular disease, and neoplasms.

Multiple hepatorenal angiomyolipomas: diagnosis with fat suppression, gadolinium-enhanced MRI

Hepatic angiomyolipoma is a rare tumor which may occur as a solitary mass or as an associated finding with tuberous sclerosis. While computed tomography allows identification of the fat component of the lesion, magnetic resonance imaging (MRI) can provide similar information, as well as multiplanar visualization and further characterization of the vascular component of the lesion. MRI utilizing fat suppression and gadolinium enhancement may best provide all of the above information, as is demonstrated in this case report, thus potentially representing the imaging modality of choice.

Diffuse disease of the liver: radiologic-pathologic correlation

Cross-sectional imaging is playing an increasing role in diagnosis of diffuse liver diseases because it clarifies, in many cases, the overlap in clinical and laboratory manifestations often present in diffuse hepatic processes and thus may eliminate the need for a biopsy. Advances in cross-sectional imaging, particularly in magnetic resonance (MR) imaging, enable further characterization of hepatic parenchymal and architectural changes, allowing closer correlation with underlying pathologic changes. Advanced imaging techniques can be used to characterize a variety of metabolic, vascular, toxic, infectious, and neoplastic diffuse liver diseases. These include more common entities such as cirrhosis, Budd-Chiari syndrome, hemochromatosis, Wilson disease, fatty change, and diffuse neoplastic disease (hepatocellular carcinoma, metastasis, and lymphoma) and uncommon entities such as schistosomiasis, sarcoidosis, and amyloidosis. Correlation of computed tomographic and MR imaging findings with underlying pathologic features is helpful in understanding the gamut of diffuse diseases of the liver.

Bubbles in the belly: imaging of cystic mesenteric or omental masses

The purpose of this article is to familiarize radiologists with the spectrum of "bubbles in the belly," including the current histologic classification of mesenteric or omental cysts. Although mesenteric and omental cystic masses are uncommon lesions, radiologists should be familiar with them as well as with other anomalies that can manifest as these cysts. The first step in diagnosing a cystic abdominal mass is to determine the organ from which the mass originates. The most common type of mesenteric or omental cyst is lymphangioma, but other types encountered include the enteric duplication cyst, the enteric cyst, the mesothelial cyst, and the nonpancreatic pseudocyst. Other cystic lesions that may be located in the mesentery or omentum include cystic mesothelioma, cystic spindle cell tumor, and cystic teratoma. Because of the overlap in imaging features of mesenteric or omental cysts and other cystic masses, histologic analysis is usually necessary to establish a diagnosis. The major role of the radiologist is to document the cystic nature of these abdominal masses and their mesenteric or omental origin.

Castleman disease mimicking an aggressive retroperitoneal neoplasm

A case of Castleman disease of the retroperitoneum in a 26-year-old woman is presented. Sonography, computed tomography, and magnetic resonance imaging demonstrated a large retroperitoneal mass with somewhat heterogeneous imaging characteristics. Although a definitive preoperative diagnosis was not possible, magnetic resonance imaging was useful in delineating the extent of the tumor and defining the characteristics of surrounding soft tissues.

Prediction of surgical resectability in patients with hepatic colorectal metastases

OBJECTIVE

To evaluate the efficacy of two distinct imaging techniques to predict, before operation, unresectability compared with standard computed tomographic scan (CT).

SUMMARY BACKGROUND

Accurate preoperative identification of the number, size, and location of hepatic lesions is crucial in planning hepatic resection for colorectal hepatic metastases. Although infusion-enhanced CT is the standard, its limitations are the imaging of relatively isodense and/or small (< 1 cm) lesions. The increased sensitivity of CT arterial portography (CTAP) may be offset by false-positive results caused by benign lesions and flow artifacts.

METHODS

Fifty-eight selected patients considered to be eligible for resection by standard CT had laparotomy. Before operation and in addition to CT, all patients had CT arterial portography and hepatic artery perfusion scintigraphy (HAPS) using radiolabeled macroaggregated albumin. Early studies showed an increased sensitivity for detecting small lesions using the invasive CTAP. Similarly, the HAPS study has detected malignant lesions not observed by standard CT.

RESULTS

Of 58 patients having laparotomy, 40 were resectable by either lobectomy (22) or trisegmentectomy (1) and the rest by single or multiple wedge resections. Eighteen patients could not be resected because of combined intra- and extrahepatic disease or the number and location of metastases. Standard CT detected 64% of all lesions (12% of lesions less than 1 cm). Unresectability was accurately predicted by CTAP and HAPS in 16 (88%) and 15 (83%), respectively, of the 18 patients considered ineligible for resection at laparotomy. Of the 40 patients who had resection for possible cure, CTAP and HAPS falsely predicted unresectability in 6 of 40 patients (15%) and in 10 of 40 patients (25%), respectively. The positive predictive value for unresectability of CTAP and HAPS was 73% and 60%, respectively. False-positive lesions after CTAP included hemangiomas, cysts, granulomas, and flow artifacts. False-positive HAPS lesions included patients in whom no tumor was found at surgery but with some identified by intraoperative ultrasound, blind biopsy, and blind resection.

CONCLUSIONS

False-positive results by HAPS and CTAP may limit the ability of these tests to accurately predict unresectability before operation and may deny patients the chance for surgical resection. The HAPS study does, however, detect small lesions not seen by CT or CTAP. Standard CT, although less sensitive, followed by surgery and intraoperative ultrasound, does not necessarily preclude patients who could be resected.

Intraluminal contrast agents for MR imaging of the abdomen and pelvis

Magnetic resonance (MR) imaging of the abdomen and pelvis with use of gastrointestinal (GI) contrast agents is slowly emerging as a valuable diagnostic tool. In the past few years, considerable effort has been expended on developing an oral contrast agent to serve as a bowel marker during abdominal and pelvic imaging. Four major categories of agents have been studied: compounds with positive contrast-enhancing characteristics (ie, which increase signal intensity), which may be either miscible or immiscible with bowel contents, and compounds with negative contrast-enhancing characteristics (ie, which decrease signal intensity), which also may be miscible or immiscible. Compared with precontrast images, MR images acquired after administration of GI contrast agents have shown increased anatomic delineation of the bowel lumen, pancreas, and paraaortic nodes, allowing increased detection of pancreatic lesions, improved assessment of bowel wall lesions, and distinction between intrahepatic and extrahepatic lesions. This review focuses on the general physics and requirements for intraluminal GI contrast media for MR imaging, the currently used intraluminal agents and their regulatory status, current and near-future availability, and cost considerations.

Primary liver neoplasms: MR imaging with pathologic correlation

Magnetic resonance (MR) imaging is a powerful tool in the evaluation of primary liver neoplasms. Determination of tumor extent and tissue characterization is provided with standard spin-echo T1- and T2-weighted imaging and is enhanced by the application of advanced sequences such as gradient-echo, fast spin-echo, and fat suppression techniques. Intravenously administered contrast agents, such as gadopentetate dimeglumine and superparamagnetic iron oxide, provide additional opportunities for lesion characterization. Knowledge of the underlying gross and microscopic pathologic features of primary hepatic neoplasms leads to a better understanding of their often complicated MR imaging appearances. The authors correlate the key pathologic features with the most significant MR imaging findings of primary benign and malignant liver neoplasms, including hemangioma, focal nodular hyperplasia, hepatocellular adenoma, infantile hemangioendothelioma, mesenchymal hamartoma, hepatocellular carcinoma, fibrolamellar carcinoma, intrahepatic cholangiocarcinoma, biliary cystadenoma and cystadenocarcinoma, angiosarcoma, hepatoblastoma, and undifferentiated embryonal sarcoma.

Recurrent biliary cystadenoma: MR imaging appearance

The authors report the case of a 37-year-old woman with a biliary cystadenoma that mimicked a liver cyst. The magnetic resonance (MR) imaging features of this rare lesion were correlated with the pathologic findings, showing the potential of MR imaging for depicting and aiding in the diagnosis of biliary cystadenoma and its recurrence.

Dose optimization of nonionic contrast agent in dynamic computed tomography scanning of the abdomen and pelvis

A prospective, randomized study was performed to examine the image quality of varying reduced doses of an intravenous (IV) nonionic contrast agent (ioversol, 320 mg/ml organically bound iodine) compared with the quality obtained using the maximum permissible dose (150 ml) of the same agent. Forty-five patients referred for abdominal-pelvic computed tomography (CT) scan were randomized into five groups to receive contrast doses equivalent to 100, 75, 65, 50, or 30% of 150 ml of contrast agent. The images were scored for diagnostic image quality in eight anatomical regions of interest and, in addition, quantitative analysis of density measurements were performed in the abdominal aorta and inferior vena cava. There was no statistically significant difference in either image quality, in any anatomical region, or in vascular density measurements between the group receiving 100% and the group receiving 75% of 150 ml of nonionic contrast agent. Patients receiving 65% and lower doses demonstrated a statistically significant decrease in enhancement, although all scans were diagnostically adequate. This study demonstrates that dynamic abdominal and pelvic CT scans obtained using a reduced dose of nonionic IV contrast agent are equivalent in diagnostic image quality compared with those scans obtained with the higher permissible dose of the same agent.