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Benign hepatic vascular neoplasms and vascular pseudolesions are commonly encountered in magnetic resonance (MR) imaging. Most of these benign lesions demonstrate not only arterial-phase hyperintensity, but also persistent enhancement on venous and delayed imaging, unlike most malignant hepatic masses. These features, along with other MR findings and morphological characteristics, may allow for more confident diagnosis and distinction from hepatic malignancy. The objective of our study was to illustrate the MR imaging findings of hepatic lesions that demonstrate both early arterial and sustained enhancement on hepatic venous and delayed phase.

Hepatic adenoma is a rare benign epithelial tumor that is usually encountered in young women who use oral contraceptives. It is clinically significant because of the risk of hemorrhage and of its low-grade malignancy potential. Adenomas usually are mildly hypervascular at contrast-enhanced CT and MR imaging, and heterogeneous due to the presence of hemorrhage, necrosis, calcifications and fat. The objective of our study was to illustrate the CT and MR imaging findings of hepatic adenoma.

Objective: To find the optimal scan timing for early arterial phase hepatic CT with adequate arterial enhancement after the aortic contrast arrival., Methods: Sixty patients were divided randomly into three groups, each of which received 2.0 mL/kg of the 300 mgI/mL contrast medium with an injection duration of 30 seconds (Group A, mean rate 3.6 mL/sec); of 25 seconds (B, 4.6 mL/sec); of 30 seconds (3.6 mL/sec) followed by a saline chaser (C)., Results: After the contrast arrival, aortic enhancement increased rapidly for 6-15 seconds (mean, 10 seconds) to the initial peak enhancement in all groups, and then, increased moderately to the maximum aortic enhancement over the following 19, 13, and 21 seconds, respectively. The mean maximum aortic enhancement in Group B (392 HU) and C (360 HU) were significantly higher than that in A (326 HU), respectively. The difference between the initial and maximum aortic enhancement was less than 50 HU., Conclusion: The optimal timing of the early arterial phase for hepatic CT arteriography is 10-15 seconds after the aortic arrival.

Purpose: We evaluated the optimal timing of arterial phase imaging for detection of hypervascular hepatocellular carcinoma by using triple arterial phase imaging with multidetector-row helical computed tomography., Materials and Methods: Forty-nine patients with 90 hypervascular hepatocellular carcinomas (3 to 50 mm in diameter; mean, 18.7 mm) underwent triple arterial phase imaging of the whole liver using a multidetector-row helical computed tomography. At 20 seconds, 30 seconds, and 40 seconds after intravenous administration of 100 mL of 300 mgI/mL of nonionic contrast medium at a rate of 4 mL/s, early, middle, and late arterial phase images were obtained serially during a single breath-hold with an interscan delay of 5 seconds. Detector-row configurations of 4 mm x 4, scan pitch of 5.5, and scan time of 5 seconds for each phase were used. Forty prospective reconstruction images of 5-mm thickness for each phase were obtained. The images from each phase were interpreted separately for detection of hypervascular hepatocellular carcinoma by 3 observers independently who were unaware of tumor burden in the liver. Sensitivity, positive predictive value, and area under the receiver operating characteristic curve values for each arterial phase were calculated and compared statistically., Results: The mean sensitivity and positive predictive values for hypervascular hepatocellular carcinoma diagnosis of blind readers were 37% and 87% for the early arterial phase, 73% and 85% for the middle arterial phase, and 49% and 81% for the late arterial phase, respectively. The middle arterial phase imaging showed significantly superior sensitivity compared with the early and late arterial phase for detecting hepatocellular carcinoma (P < 0.05). Mean area under the receiver operating characteristic curve value of the middle arterial phase imaging (0.84) was significantly higher that that of the early (0.56) or late arterial phase (0.62; P < 0.05)., Conclusion: If a single arterial phase is used for diagnosis of hypervascular hepatocellular carcinoma, the middle phase (delay time of 30 seconds) is optimal.

Objective: To report the helical multiphasic computed tomography (CT) findings in 30 patients with hepatocellular-cholangiocarcinoma., Method: We evaluated age, gender, tumor risk factors, serum tumor markers, symptoms, and tumor morphology and enhancement on helical multiphasic CT in 30 patients., Results: Twenty-six of 30 patients (86%) were men. Patients had an age range of 27-78 years (mean = 58 years). Abdominal signs or symptoms were present in 21 of 30 patients, and 25 of 30 (83%) had chronic liver disease. Helical CT demonstrated a well-defined tumor in all patients with signs of malignancy such as hepatic hypervascularity (63%), biliary obstruction (17%), satellite lesions (40%), and lymphadenopathy (27%). Portions of the tumor were hyperattenuated on arterial-phase imaging and hypoattenuated on all other phases, whereas other portions showed delayed persistent enhancement, sometimes (27%) with hepatic capsular retraction, findings that have been reported to be characteristic of hepatocellular carcinoma and cholangiocarcinoma, respectively., Conclusion: The diagnosis of hepatocellular-cholangiocarcinoma should be considered when a hepatic tumor has CT features of both hepatocellular carcinoma and cholangiocarcinoma. Radiologists should be aware of this tumor type so that the biopsy is performed properly to allow sufficient tissue sampling.

Background: Hepatic artery stenosis and thrombosis are common complications in liver transplant patients. Digital subtraction angiography (DSA) has served as the gold standard to make this diagnosis. More recently, three-dimensional helical computed tomographic arteriography (3D CTA) with maximum intensity projection and shaded surface display techniques has been compared with DSA. The purpose of this study was to determine whether 3D CTA with the volume rendering technique is a useful and accurate tool in the detection of vascular complications after liver transplantation., Methods: Thirty-five consecutive liver transplant patients underwent 3D CTA with volume rendering technique. The standard of reference was DSA for 20 patients and imaging and clinical follow-up for 15 patients. Two blinded reviewers evaluated the axial and 3D CTA images in consensus., Results: 3D CTA with volume rendering technique detected 10 hepatic artery stenoses, six hepatic artery thromboses, two hepatic artery pseudoaneurysms, two splenic artery aneurysms, two portal vein stenoses, and four redundant hepatic arteries. In one case computed tomography (CT) detected a moderate hepatic artery stenosis, while conventional angiography showed a normal artery. The sensitivity of CT for detecting vascular lesions was 100%, specificity was 89% (8 of 9), accuracy was 95% (19 of 20), positive predictive value was 92% (11 of 12), and negative predictive value was 100% (8 of 8)., Conclusions: 3D CTA is a useful and accurate noninvasive technique for detection of vascular complications in liver transplant patients.

Purpose: The purpose of our study was to evaluate the effect of bolus infusion of contrast medium (ionic versus nonionic) on the incidence of nausea and anaphylactoid reactions., Method: We prospectively studied 1,827 patients who had bolus enhanced body CT scans and divided them into four groups: 725 patients received higher osmolality contrast medium (HOCM) at the slower bolus rate of 1-2.5 ml/s (SLOW-HOCM group); 650 patients were in the FAST-HOCM group and received the same ionic contrast medium at 4-5 ml/s; 250 patients received lower osmolality contrast medium (LOCM) at 1-2.5 ml/s, forming the SLOW-LOCM group; and 202 patients in the FAST-LOCM group got the same nonionic agent at 4-5 ml/s., Results: We found no significant difference in the rate of nausea among the first three groups: SLOW-HOCM (3.9%), FAST-HOCM (4.9%), and SLOW-LOCM (3.2%). A statistically significant lower incidence of nausea (0.5%) was found in the FAST-LOCM group. Anaphylactoid reactions were significantly more common in both groups who received HOCM (8.3 and 9.1%) compared with the groups who received LOCM (2.0 and 2.5%)., Conclusion: The bolus injection of warmed ionic contrast medium at a rate of 1-2.5 ml/s causes no significant increase in nausea compared with similar infusion rates of nonionic agents. For CT protocols that require infusion rates of 4-5 ml/s, the use of a nonionic agent is associated with a significantly reduced prevalence of nausea. The prevalence of anaphylactoid reactions is not affected by the rate of injection.

Objective: To determine the potential risks of the use of oral contrast medium for bowel opacification in abdominal trauma computed tomography (CT) scanning., Design: A retrospective chart review., Materials and Methods: 506 consecutive patients who had CT evaluation of acute blunt abdominal trauma. All had both intervenous and "oral" administration of iodinated contrast material. Alert cooperative patients drank 450 ml of a 2.5% solution of Gastroview, while obtunded or uncooperative patients had the same volume and concentration of medium administered through a nasogastric tube, following endotracheal intubation., Results: No patients had aspiration of the contrast medium or gastric contents attributable to performance of the CT scan, except for one patient who had inadvertent installation of contrast through a tube that had been placed into the right main bronchus rather than the stomach., Conclusions: Bowel opacification is important for optimal CT evaluation of abdominal trauma and can be used with confidence. Attention to proper preparation and administration of the contrast material and, more importantly, control of the patient's airway by appropriate tracheal intubation are essential to assure the safety of the procedure.

Intravascular contrast media produce pulmonary edema in one rat model, but not in dogs or pigs. In humans, pulmonary edema after contrast media is rarely diagnosed, but subclinical edema could be more frequent than believed previously. Therefore, the authors prospectively studied the effects of diatrizoate (n = 5) and ioxaglate (n = 5) on extravascular lung water, central blood volume, and cardiac output in ten patients undergoing routine radiographic procedures. Variables were measured by thermal-dye dilution before and every 5 minutes after completion of the procedure for four repetitions. Extravascular lung water and central blood volume did not change significantly, indicating that pulmonary edema or pulmonary congestion did not occur. Cardiac output was elevated by 10.6% immediately after the procedure, but returned to baseline during the 10 following minutes. The authors conclude from this preliminary study in a small number of patients that intraarterial contrast media (less than 1.5 g/kg body weight of iodine) did not produce pulmonary edema or pulmonary congestion, even at a subclinical level.

We report a case of cystic Hodgkin's disease of the thymus that was evaluated preoperatively by computed tomography (CT). Although this is an uncommon cause of an anterior mediastinal mass, it should be considered in the differential diagnosis along with cystic thymoma and cystic treatomas, since the treatment of the these lesions is dramatically different. The CT appearance and pathology of this lesion are discussed.

Nine surgically proven cases of pyogenic psoas abscesses are presented. The most common finding on computed tomography was diffuse enlargement of the psoas with a central low density area corresponding to an abcess cavity. This was noted in seven patients. The anatomy of the psoas muscle and retrofascial area is discussed, as well as the changing etiology and bacteriology of psoas abscesses.

Computed tomographic (CT) findings are reviewed in nine patients with clinically unsuspected abdominal abscesses. None of the patients in this series had significant fever or leukocytosis. Localized pain or a palpable mass was the primary clinical feature in seven patients. Computed tomography demonstrated encapsulated fluid collections without gas in five patients representing chronic abscess. Computed tomography was diagnostic of an abscess in three patients and guided aspiration was helpful in demonstrating an abscess in two other patients. The inability to make a correct preoperative diagnosis of an abscess in four of the nine cases was due to a low level of clinical suspicion, a nonspecific CT appearance, and failure to perform diagnostic aspiration.

The computed tomography (CT) findings in 10 patients who presented with lumbosacral radicular symptoms are reported. The CT scans were performed after the more commonly used radiologic studies, including plain films and myelography, had failed to completely define the nature or extent of the underlying disease process. The final diagnoses were metastatic neoplasm to the spine and soft tissue in six cases, primary neoplasm of the sacrum or soft tissue in three cases, and tuberculous osteomyelitis and abscess in one case. The limitations and potential complications of the various radiologic examinations are discussed, and the potential value of CT in selected patients with lumbosacral neuropathy is presented.

Five patients with clinically unsuspected gastrointestinal perforation were evaluated preoperatively with computed tomography (CT). In each case the CT demonstration of pneumoperitoneum established the diagnosis of a ruptured viscus and prompted early surgical intervention. The site of perforation was apparent on CT in four of the five patients. Plain radiographs including upright chest films (two patients) and supine radiographs of the abdomen (one patient) were interpreted as negative for free air prior to CT. The CT features of pneumoperitoneum and its clinical implications are reviewed.

Computed tomography (CT) can be helpful in the detection and diagnosis of aortic arch malformations, including anomalous right subclavian artery, left sided aortic arch with right descending aorta, right sided, aorta with anomalous left subclavian artery or mirror image branching, and double aortic arch. This paper reviews the CT findings in 10 such patients. Computed tomography can confirm the presence of an aortic anomaly suspected from plain radiographs or can detect a vascular anomaly when the plain radiograph suggests the presence of a mediastinal mass.

The selection of patients and technique for computed tomographic (CT) scanning of abdominal trauma are presented. CT is capable of detecting a wide variety of abdominal and retroperitoneal traumatic lesions and appears to be highly sensitive and specific. To a large extent it has displaced other modalities such as radionuclide scanning, ultrasonography, angiography, and peritoneal lavage in the comprehensive acute evaluation of the patient with abdominal trauma. Effects on patient management are evident in decreased incidence of unnecessary exploratory laparotomy, shorter hospital stays for observation, and earlier and more specific surgical intervention in appropriate cases. In light of these considerations, CT has proven very cost-effective.

The role of computed tomography (CT) in defining the extent of local tumor invasion was reviewed retrospectively in 22 patients with biopsy proven malignant lesions of the bladder. These included 14 cases of primary bladder carcinoma and 8 cases of pelvic malignancies with secondary invasion of the bladder. Computed tomography proved accurate in detecting lymph node enlargement, obvious extravesical masses, and relatively small mural of mucosal lesions of the bladder. However, CT was not able to reliably predict microscopic invasion of either the serosal surface of the bladder by pelvic malignancies or microscopic invasion of the perivesical fat by intrinsic bladder carcinoma. These factors, in addition to the inability of CT to detect metastases in normal sized lymph nodes, appear to limit the overall accuracy of CT in the evaluation of locally invasive pelvic malignancies. Nevertheless, CT appears to be a useful noninvasive screening technique to avoid needless radical surgery in advanced lesions with bladder invasion.

Mandatory surgical exploration of penetrating renal injuries has been advocated for adequate assessment and repair of renal and retroperitoneal injuries. We evaluated 27 consecutive patients with deep stab wounds of the flank and back who were thought to be at risk for renal injury. Twenty-two patients were studied by CT, 11 by excretory urography, and three by angiography. No correlation was found between the presence and amount of hematuria and the extent of renal injury. Excretory urography was also of little use; the extent of renal parenchymal injury was underestimated, overestimated, or indeterminate in many cases. Computed tomography gave an accurate assessment of the extent of parenchymal damage, perirenal hemorrhage, extravasation of urine, and extrarenal injuries. Angiography was rarely required to better define renal vascular injuries. Only seven patients required surgical repair; the 20 patients managed nonoperatively included seven patients with renal lacerations considered minor by CT evaluation. We conclude that most patients with penetrating trauma do not require surgical exploration. The combination of clinical and CT criteria allows confident management in almost all cases. Computed tomography should be the primary diagnostic study in patients with penetrating back or flank trauma judged to be at risk for renal or other retroperitoneal injury.

The CT findings are reviewed in two patients with injuries to the gallbladder following blunt abdominal trauma. In one patient with a laceration of the cystic artery a large intraluminal clot was identified within the gallbladder associated with extensive hemoperitoneum. Another patient presented with extensive bile leakage into the peritoneal cavity 72 h after blunt trauma due to laceration of the fundus of the gallbladder. The clinical features of blunt trauma to the gallbladder and the utility of CT in this entity are reviewed.

Computed tomographic scans were reviewed in 46 patients with documented omental pathology to analyze the radiographic characteristics of benign and malignant disease. The normal omentum is identified on CT of the abdomen as a homogeneous fat density anterior to the transverse colon. Four distinct patterns of omental pathology were identified: (a) omental caking, (b) finely infiltrated fat with a "smudged" appearance, (c) cystic masses, and (d) discrete nodules. The smudged pattern of omental pathology was identified most frequently; it was present in 20 to 39 patients with malignant disease and in five of seven patients with inflammatory disease. Omental caking was present in 17 of 46 patients but was only identified in malignant disease. Computed tomography provides the most reliable radiographic technique to routinely evaluate omental pathology. A thorough understanding of the variable appearance of omental disease is important in identifying omental pathology.

Of 104 patients evaluated for thoracic sepsis by CT, 22 patients had both CT and clinical evidence of mediastinal infections. The CT findings in these patients were reviewed and compared with a control group of seven postoperative patients following uncomplicated median sternotomy. Based on CT appearance, patients were classified into one of three groups: (a) diffuse soft tissue infiltration with or without gas (i.e., mediastinitis) (10 patients); (b) focal mediastinal abscess (four patients); (c) mediastinal infection associated with empyema or subphrenic abscess (eight patients). Computed tomography proved reliable in distinguishing diffuse mediastinitis from a localized drainable abscess. However, in the absence of mediastinal gas, CT could not differentiate mediastinitis from benign postoperative changes. Computed tomography was helpful in identifying associated empyemas and a variety of other secondary complications. In five of six patients with mediastinal abscess, CT demonstrated communication or contiguity with four empyemas and one subphrenic abscess. Closed chest tube drainage of the empyemas and percutaneous drainage of the subphrenic abscess combined with antibiotic therapy were successful in treating the mediastinal abscess in these five patients. Although overall mortality for mediastinal infection in this series was 27%, there was a 50% mortality for patients with diffuse mediastinitis.

Twenty-four patients with signs on computed tomography (CT) of mesenteric or intestinal injury were treated over a 5-year period (1980-1984). All patients were the victims of blunt abdominal trauma. Nine patients with CT evidence of mesenteric or bowel hematomas were observed without adverse outcome. Fifteen were operatively explored, with 14 having injuries similar to the findings on the preoperative CT scans. In the group that had surgery, either thickened bowel or free intraperitoneal fluid (blood or less dense fluid) or both were present in all but one patient. Extraluminal air (three cases) or Gastrografin (Squibb) (one case) were absolute indications for surgery, as were bowel wall or mesenteric hematomas accompanied by substantial amounts of intraperitoneal fluid. The patient's history, physical examination, and initial laboratory values are important in proper selection of patients for CT evaluation. We feel that CT appears to offer certain definite advantages over peritoneal lavage in evaluation of bowel and mesenteric injuries and can reliably help to distinguish the injuries that require surgical repair from those that can be safely monitored and observed.

A case of pseudomembranous colitis is reported in which computed tomography (CT) played an important role in the diagnosis and differentiation from other causes of fever and abdominal pain. It is important to look for CT evidence of primary bowel disease when scans are performed for possible abdominal abscess, since these two conditions may present similar clinical features.

A retrospective CT study was undertaken to evaluate nonneoplastic extragastric lesions associated with gastric wall thickening (GWT). A total of 70 cases was reviewed including 44 with acute pancreatitis, 6 with infected left upper quadrant fluid collections, and 20 with noninfected left upper quadrant fluid collections. Patients with acute pancreatitis and measurable gastric walls disclosed GWT in 67% of cases. All patients with infected left upper quadrant fluid collections (including abscesses and infected splenic hematomas) adjacent to the stomach exhibited GWT on computed tomography (CT). No patients with noninfected perigastric left upper quadrant fluid collections had GWT. Gastric wall thickening has been emphasized as an important feature in CT staging of gastric malignancies and has been noted in intrinsic gastric inflammatory disease. We conclude that extragastric inflammatory processes are commonly identified on CT and can be demonstrated to account for GWT, which appears to be a relatively sensitive and specific sign for distinguishing inflammatory from noninflammatory perigastric lesions.

Because of the increased incidence of serious infection in patients who have had splenectomy, conservative management of patients who have had splenic trauma is becoming more prevalent. One newer modality is splenorrhaphy, the suture repair of splenic lacerations. We report a case of splenic trauma treated by splenorrhaphy and later evaluated by computed tomography (CT). Certain characteristic CT features, such as the visualization of Teflon pledgets, illustrate the importance of distinguishing surgical artifacts from traumatic sequelae.