Combined hepatocyte-selective and blood-pool contrast agents for the CT detection of experimental liver tumors in rabbits.

PURPOSE: To determine the imaging characteristics of a new computed tomographic (CT) contrast material with both hepatocyte-selective and blood-pool components (iodinated triglyceride (ITG)-dual) versus standard iohexol. MATERIALS AND METHODS: VX2 carcinoma was inoculated in seven rabbits. Animals underwent nonenhanced, iohexol-enhanced (600 mg of iodine per kilogram of body weight), and ITG-dual-enhanced (blood-pool moiety, 100 mg of iodine per kilogram; hepatocyte-selective moiety, 100 or 200 mg of iodine per kilogram, injected 90 minutes apart) helical CT. Livers were removed, preserved in formalin, suspended in agar, and sectioned transversely at 3-mm intervals. Attenuation values for normal liver and tumors were obtained, and blinded readers evaluated images for lesions by using a modified free-response receiver operating characteristic (ROC) method. RESULTS: A total of 47 separate tumor sites were detected at pathologic examination. ITG-dual-enhanced scans obtained with 300 mg of iodine per kilogram demonstrated similar liver opacification to iohexol-enhanced scans obtained with 600 mg of iodine per kilogram, but with less lesion enhancement, which resulted in better liver-to-lesion contrast. Blinded readers had a higher sensitivity, accuracy, and area under the ROC curve for ITG-dual-enhanced scans as compared with iohexol-enhanced scans (P: <.01). CONCLUSION: ITG-dual-enhanced CT quantitatively and qualitatively improved liver lesion detection versus iohexol-enhanced CT. Future clinical trials with various human tumor types after potential approval for human use are needed to determine the ultimate role of this or other dual-mechanism contrast materials.

MR imaging of the pleura and chest wall.

Evaluation of pleural and chest-wall disease begins with a chest radiograph. In many cases, further evaluation of the chest wall and pleura requires cross-sectional imaging with CT scan or MR imaging. MR imaging is reserved for specific cases of tumors, infections, pleural effusions, and masses. The superior soft-tissue contrast of MR imaging is useful in evaluating the extent of infections and tumors involving the pleura and chest wall. The multiplanar capability of MR imaging aids in the evaluation of chest wall and pleural abnormalities, particularly in the apical regions.

Colonic wall thickening in patients with cirrhosis: CT findings and clinical implications.

OBJECTIVE: The purpose of this study was to determine the prevalence and spectrum of colonic wall changes in patients with cirrhosis and to determine the association between these colonic wall changes and portal hypertension. MATERIALS AND METHODS: Abdominal CT examinations of 57 patients with cirrhosis were evaluated for colonic abnormalities including bowel wall thickening and pneumatosis. The degree and extent of colonic involvement, other CT features of cirrhosis including ascites and portal hypertension, and clinical symptoms were recorded. A correlation was made with available colonoscopy, exploratory laparotomy, and pathologic results. RESULTS: Colonic wall abnormalities were seen in 37% (21/57) of the patients with cirrhosis, 25% (14/57) of whom had isolated or predominantly right-sided colonic changes. Abnormal bowel wall thickening (ranging from 6 mm to 3 cm in thickness) was present in 35% of the patients. Pneumatosis was found in 4% of the patients. Of the 18 liver transplant recipients who had CT examinations before and after liver transplantation, colonic changes were seen in 44% preoperatively but in only 6% postoperatively. Isolated right-sided colonic changes and diffuse colonic changes were associated with varices in 93% and 100% of the patients, respectively; with ascites in 93% and 100%, respectively; and with splenomegaly in 83% and 86%, respectively. Specific or focal bowel symptoms were present in only 29% of the patients with colonic changes, whether the changes were diffuse or isolated to the right side. CONCLUSION: Thirty-five percent of the patients with severe cirrhosis who underwent CT were shown to have colonic wall thickening; two thirds of these patients had thickening limited predominantly to the right colon. We postulated that predominantly right-sided colonic wall thickening may be related to changes in blood flow and hydrostatic pressures caused by portal hypertension. Many patients with isolated or predominately right-sided colonic wall thickening did not have specific or focal bowel symptoms, and in most patients, the colonic wall thickening resolved after successful liver transplantation, requiring no further testing. On the other hand, we found that pneumatosis or severe diffuse colonic wall thickening may indicate a more serious colonic problem such as ischemia or infection with Clostridium difficile and should prompt further investigation.

Non-contrast-enhanced helical computed tomography for the evaluation of patients with acute flank pain.

The purpose of this study was to determine the sensitivity, specificity, and positive predictive value of non-contrast-enhanced helical CT as the primary imaging modality for the evaluation of patients with acute flank pain at the University of Wisconsin. A retrospective review of 163 computed tomography (CT) examinations, dating from 3/4/97 to 3/25/98, was performed. Statistical calculations were performed using only clinically-confirmed data. Sixty-five true positives, 3 false positives, 64 true negatives, and 1 false negative yield a sensitivity of 98.5%, a specificity of 95.5%, and a positive predictive value of 95.6%. A timely diagnosis of non-genitourinary system pathology occurred in 7% of cases, improving the overall efficacy of this modality for the evaluation of flank pain. The University of Wisconsin experience confirms the accuracy and efficacy of using non-contrast-enhanced helical CT in the diagnosis of a suspected obstructing ureteral calculus. The highly accurate and timely diagnosis of an obstructing ureteral calculus, or of extraurinary tract pathology, establishes non-contrast-enhanced helical CT as the diagnostic study of choice for the evaluation of the patient with acute flank pain.

A multisite phase III study of the safety and efficacy of a new manganese chloride-based gastrointestinal contrast agent for MRI of the abdomen and pelvis.

The purpose of this study was to evaluate the safety and efficacy of a manganese chloride-based oral magnetic resonance (MR) contrast agent during a Phase III multisite clinical trial. Two hundred seventeen patients were enrolled who were already scheduled for MRI of the abdomen and/or pelvis. In this group of patients, it was postulated that the use of an oral agent would better allow discrimination of pathology from bowel. Patients with known gastrointestinal pathology including peptic ulcer disease, inflammatory bowel disease, obstruction, or perforation were excluded to minimize confounding variables that could affect the safety assessment. Of these 217 patients, 18 received up to 900 mL of placebo, and 199 patients were given up to 900 mL of a manganese chloride-based oral contrast agent, LumenHance (Bracco Diagnostics, Inc.). Safety was determined by comparing pre- and post-dose physical examinations, vital signs, and laboratory examinations and by documenting adverse events. Efficacy was assessed by unblinded site investigators and two blinded reviewers who compared pre- and post-dose T1- and T2-weighted MRI scans of the abdomen and/or pelvis. In 111 (57%) of the 195 cases evaluated for efficacy by site investigators (unblinded readers), MRI after LumenHance provided additional diagnostic information. Increased information was found by two blinded readers in 52% and 51% of patients, respectively. In 44/195 cases (23%) unblinded readers felt the additional information would have changed patient diagnosis and in 50 patients (26%), it would have changed management and/or therapy. Potential changes in patient diagnosis or management/therapy were seen by the two blinded readers in 8-20% of patients. No clinically significant post-dose laboratory changes were seen. Forty-eight patients (24%) receiving LumenHance and four patients (22%) receiving placebo experienced one or more adverse events. Gastrointestinal tract side effects were most common, seen in 29 (15%) of LumenHance patients and in 3 (17%) of the placebo patients. LumenHance is a safe and efficacious oral gastrointestinal contrast agent for MRI of the abdomen and pelvis.

Diagnosis and staging of ovarian cancer: comparative values of Doppler and conventional US, CT, and MR imaging correlated with surgery and histopathologic analysis--report of the Radiology Diagnostic Oncology Group.

PURPOSE: To determine the optimal imaging modality for diagnosis and staging of ovarian cancer. MATERIALS AND METHODS: Two hundred eighty women suspected to have ovarian cancer were enrolled in a prospective study before surgery. Doppler ultrasonography (US), computed tomography (CT), and magnetic resonance (MR) imaging were used to evaluate the mass; conventional US, CT, and MR imaging were used to stage spread. RESULTS: All three modalities had high accuracy (0.91) for the overall diagnosis of malignancy. In the ovaries, the accuracy of MR imaging (0.91) was higher than that of CT and significantly higher than that of Doppler US (0.78). In the extraovarian pelvis and in the abdomen, conventional US, CT, and MR imaging had similar accuracies (0.87-0.95). In differentiation of disease confined to the pelvis from abdominal spread, the specificity of conventional US (96%) was higher than that of CT and significantly higher than that of MR imaging (88%), whereas the sensitivities of MR imaging (98%) and CT (92%) were significantly higher than that of conventional US (75%). CONCLUSION: MR imaging is superior to Doppler US and CT in diagnosis of malignant ovarian masses. There is little variation among conventional US, CT, and MR imaging as regards staging.

CT-monitored percutaneous cryoablation in a pig liver model: pilot study.

PURPOSE: To determine the safety and feasibility of percutaneous cryoablation with computed tomographic (CT) guidance in a pig liver model. MATERIALS AND METHODS: Nine angiographic balloons (mean diameter, 9 mm) were placed in the livers of seven domestic pigs (mean weight, 30.0 kg +/- 14.0 [SD]) as tumor-mimicking lesions. By using ultrasonographic and CT guidance, two 2.4- or 3.0-mm cryoprobes were placed flanking the balloon, and a 15-20-minute freezing process was performed. Hemostasis was achieved by placing absorbable cellulose fabric down the probe tract. After 24-96 hours, animals were sacrificed, and their livers were removed and were sectioned axially at 5-mm intervals for comparison with CT images. RESULTS: All animals survived the procedure without complication. No serious hemorrhage was found in any case. Ice balls were readily visualized at CT because they appeared as areas of decreased attenuation (1.0 HU +/- 20.7) when compared with areas of normal liver (48.2 HU +/- 6.3, P < .05). The mean ablative margin was 1.7 cm, and only one of nine cases, the one with probe failure, had a positive margin. Beam-hardening artifact from the metal probes was present but did not interfere with the procedure. Ice-ball size and shape corresponded closely to the area of necrosis determined at histopathologic analysis. CONCLUSION: CT-monitored percutaneous cryoablation is feasible and safe in this pig liver model.

Pulmonary mucosa-associated lymphoid tissue lymphoma: CT and pathologic findings.

OBJECTIVE: The objective of this study was to determine the CT findings in pulmonary mucosa-associated lymphoid tissue lymphoma and to correlate these CT findings with histologic specimens. CONCLUSION: In the 11 patients reviewed, the most common CT appearance of pulmonary mucosa-associated lymphoid tissue lymphoma was consolidation with air bronchograms, correlating histologically with a cellular lymphocytic infiltrate expanding the interstitium and compressing adjacent alveoli, producing air bronchograms.

Imaging of cardiac transplantation complications.

Common complications of cardiac transplantation include infection, rejection, accelerated coronary artery atherosclerosis, and lymphoproliferative disease. The authors reviewed radiographic and computed tomographic (CT) features of cardiac transplantation and its complications in a series of 232 patients (with 89 complications and 49 deaths). Normal postoperative findings in the first few weeks after surgery included enlarged cardiac silhouette, pneumomediastinum, pneumothorax, pneumopericardium, subcutaneous emphysema, and mediastinal widening. Infection was the most common complication, with pneumonia being the leading infectious condition (28 cases, with Aspergillus [n = 11] and cytomegalovirus [n = 10] being the most common pathogens) and the cause of death in seven cases. Although many cases of pulmonary infections occur in the first 3-4 months after surgery, in this series several cases developed up to 3 years afterward. Radiographic signs of acute rejection were nonspecific in the eight patients affected who died, and endomyocardial biopsy was used to confirm the suspected diagnosis. Accelerated atherosclerosis occurred in 13 patients between 10 months and 6.5 years after transplantation and led to death in eight. Lymphoproliferative disorders, which range from benign lymphoid hyperplasia to malignant lymphoma and which are the third leading cause of death beyond the immediate perioperative period in heart transplant recipients, developed in four patients who later died. Other complications related to endomyocardial biopsy and cardiothoracic surgery (i.e., pneumothorax, hemothorax, pneumomediastinum, mediastinitis, aortic dissection, aortic pseudoaneurysm, and pulmonary embolism) occurred in 31 cases and were diagnosed with radiography and CT.

Imaging pulmonary disease in AIDS: state of the art.

The spectrum of pulmonary diseases in AIDS including infections and neoplasms that affect the lungs are reviewed. Characteristic plain film and CT findings are illustrated.

Microvascular pulmonary emboli secondary to precipitated crystals in a patient receiving total parenteral nutrition: a case report and description of the high-resolution CT findings.

A patient with a history of a small-bowel transplant that was subsequently resected required total parenteral nutrition for nutritional supplementation. While receiving therapy, he developed chest tightness, shortness of breath, and fever. The chest radiograph showed bilateral reticulonodular opacities, and the high-resolution CT scan demonstrated diffuse, poorly marginated micronodular opacities in a miliary pattern. Pathology specimens obtained by transbronchial biopsy revealed amorphous material obstructing the pulmonary microvasculature. Microvascular emboli secondary to precipitated crystals is a potential complication of total parenteral nutrition. An awareness of the factors that influence crystal solubility may prevent adverse interactions in patients who require parenteral nutrition.

Evaluation of an experimental low-attenuation gastrointestinal contrast agent for CT imaging of intestinal ischemia in an animal model.

RATIONALE AND OBJECTIVES: The authors evaluated the use of MRX-320, a low-attenuation, expansile oral contrast agent, for the demonstration of intestinal ischemia in an animal model. MATERIALS AND METHODS: Nine dogs were given either MRX-320, water, or diatrizoate as an oral contrast agent through a jejunostomy tube. Two dogs received no oral contrast agent. Helical computed tomography (CT) was performed before the intravenous injection of 2.5 mL/kg iohexol at 4 mL/sec, during the arterial phase, and during the portal venous phase. Mesenteric ischemia was surgically induced, and the imaging protocol was repeated. Three readers rated the randomly assigned images for quality and demonstration of ischemia. Attenuation values for the intestinal lumen and wall were recorded. RESULTS: Examinations performed with MRX-320 provided the best discrimination between ischemic and nonischemic conditions (P < .05), followed by examinations with no oral contrast medium, examinations with water, and examinations with diatrizoate. Images obtained with MRX-320 also scored significantly higher on measures of image quality than those obtained with water or no oral contrast medium (P < .05). On images obtained with MRX-320, the bowel lumen measured -836.5 HU (P < .05 compared with other techniques). Water provided the least uniformity of distention, and diatrizoate provided the least mucosal detail. CONCLUSION: The use of MRX-320 as an oral contrast agent with an intravenous bolus of iohexol at CT increased reader confidence for the diagnosis of intestinal ischemia and improved subjective measures of image quality.

Radiographic and CT findings of blunt chest trauma: aortic injuries and looking beyond them.

Increasingly, helical CT is being used to screen trauma patients for aortic injury. Most aortic injuries visible at CT occur at or near the level of the ligamentum arteriosus; these injuries manifest as mediastinal hematoma, aortic contour deformity, intimal flaps, intraluminal debris, pseudoaneurysm, and pseudocoarctation. In the process of searching for aortic injury, however, the radiologist should not overlook other serious and more common thoracic injuries. Tracheobronchial tears appear at CT and radiography with persistent pneumothorax, subcutaneous emphysema, "fallen lung" sign, and malposition of endotracheal tube. The ruptured diaphragm, which tears more often on the left, appears asymmetric, irregular, or discontinuous, with herniation of bowel or viscera into the chest. In esophageal rupture, CT and radiography demonstrate left pneumothorax, pneumomediastinum, subcutaneous emphysema, and pleural effusion and atelectasis on the left. CT is better than trauma radiography for depicting fractures of the thoracic vertebral bodies and ribs, as well as for revealing pulmonary contusions and lacerations. CT is also useful for demonstrating unsuspected injuries caused by seat belts. Observation of these injuries should prompt a search for other serious internal organ injuries.

Utilization of computed tomography in patients hospitalized with community-acquired pneumonia.

The objective of the study was to assess the frequency of the use of chest computed tomography in 385 adults hospitalized with community-acquired pneumonia and determine whether the computed tomography examinations yielded additional diagnostic information. Also, if additional information was obtained, the study determined whether it changed the patient's treatment plan.

Arterio-esophageal communication from a ruptured aberrant right subclavian artery aneurysm. CT diagnosis.

We report the computed tomography (CT) findings of an arterio-esophageal communication from an aberrant right subclavian artery aneurysm which had eroded into the esophagus. Pathologic correlation is provided. To our knowledge, this is the first CT demonstration of an aberrant right subclavian aneurysm causing a communication to the esophagus reported in the literature. Previously, one CT case of a left aberrant subclavian artery aneurysm that had ruptured into the esophagus, had been described. The characteristic location of the aberrant vessel with aneurysmal dilation and the presence of abnormal air identified within the wall of the aneurysm on CT, helped establish the diagnosis antemortem.

Acute, life-threatening complications of lung transplantation.

Acute, life-threatening complications of lung transplantation are common in all reported series. The clinical courses and images of 70 patients who underwent heart-lung (n = 5), bilateral sequential lung (n = 31), or single-lung (n = 38) transplantation were retrospectively reviewed. Sixty-five acute, life-threatening complications occurred in 26 patients (37%) within 3 months after transplantation. Nine deaths occurred as a result of these complications for a mortality rate due to acute complications of 13%. The deaths were a result of bleeding (n = 4), sepsis (n = 2), severe acute rejection and adult respiratory distress syndrome (n = 1), multiorgan failure (n = 1), and diffuse alveolar damage and respiratory failure (n = 1), a distribution of causes similar to those in other reported series. Specific diagnoses that can be made with imaging include hemothorax, lung torsion, pneumomediastinum, pulmonary embolism, pneumothorax, bronchial anastomotic dehiscence, lung collapse, paralysis of the diaphragm, and sternal dehiscence.

CT depiction of experimental liver tumors: contrast enhancement with hepatocyte-selective iodinated triglyceride versus conventional techniques.

PURPOSE: To compare findings at computed tomography (CT) enhanced with a hepatocyte-selective contrast agent (iodinated triglyceride) and/or iohexol and at CT during arterial portography (CTAP). MATERIALS AND METHODS: Rabbit livers were directly inoculated with VX2 carcinoma. Results were compared for five helical CT examinations: unenhanced CT, iohexol-enhanced CT (600 mg iodine per kilogram of body weight [mg I/kg]), CTAP (with iohexol [600 mg I/kg]), triglyceride-enhanced CT (126 mg I/kg), and dual-contrast-enhanced CT (triglyceride plus iohexol [425 mg I/kg]). Attenuation of normal liver and tumor were compared with analysis of variance techniques and blinded reader evaluations. RESULTS: Normal liver attenuation was greatest at CTAP (127.3 HU +/- 5.3 [mean +/- standard error of the mean]), followed by dual-contrast-enhanced CT (112.4 HU +/- 1.2), iohexol-enhanced CT (97.9 HU +/- 2.2), triglyceride-enhanced CT (82.3 HU +/- 1.1), and unenhanced CT (54.9 HU +/- 1.8). Liver-to-lesion attenuation difference at triglyceride-enhanced CT was significantly greater than at iohexol-enhanced CT (P < .05), and attenuation differences at dual-contrast-enhanced CT were comparable to those at CTAP. Tumors did not enhance at triglyceride-enhanced CT, which increased conspicuity. Sensitivity values for lesion detection at dual-contrast-enhanced CT were greater than those at iohexol-enhanced CT or at CTAP (P < .05). CONCLUSION: At CT enhanced with triglyceride (especially when combined with iohexol), sensitivity values and liver-to-lesion attenuation differences were greater with lower iodine doses than with iohexol or at CTAP.