Fatty infiltration of the liver: demonstration by proton spectroscopic imaging. Preliminary observations

Two normal volunteers and three patients with CT evidence of fatty infiltration of the liver (two nonuniform, one diffuse) were studied to determine whether magnetic resonance imaging using a pulse sequence designed to differentiate fat and water could be used to detect fatty infiltration of the liver in human beings. The magnetic resonance technique used a modified spin echo technique (simple proton spectroscopic imaging) that was designed specifically to exploit the difference in the rate of precession between the protons in a water molecule and the protons in a fatty acid molecule. Images were obtained using in-phase and opposed techniques and were added or subtracted in order to obtain pure water and pure fat images. Quantitative data showed that fatty liver can be separated from normal liver using the spin echo technique, and that the opposed image of the proton spectroscopic technique is more sensitive to small changes in hepatic fatty content than in-phase images with any echo time.

Differentiation of complicated cholecystitis from gallbladder carcinoma by computed tomography

Differentiation between complicated cholecystitis and advanced gallbladder carcinoma can be difficult when clinical findings are confusing. Computed tomographic (CT) scans were reviewed from 22 patients with a surgical diagnosis of complicated cholecystitis (11 cases) or advanced gallbladder carcinoma (11 cases). The presence of a curvilinear low-attenuation "halo" around the gallbladder wall was specific for complicated cholecystitis. Findings indicative of gallbladder carcinoma included a focal soft-tissue mass, biliary obstruction at the level of the porta hepatis, and direct hepatic invasion or metastases. Other findings, such as diffuse wall thickening, streaky soft-tissue densities in the pericholecystic fat, and thickening of the hepatoduodenal ligament, could be seen in both entities and, therefore, were less useful in differentiating these two disease processes. Knowledge of these differential CT findings may result in a more accurate preoperative diagnosis.

Computed tomography of fatal hepatic rupture due to peliosis hepatis

Hepatic rupture with subcapsular hematoma and hemoperitoneum is shown by CT in a patient with peliosis hepatis. Peliosis hepatis is pathologically characterized by blood-filled cystic spaces in the liver associated with the administration of anabolic androgenic steroids or oral contraceptive agents, particularly those with large components of estrogen. We report a fatal case in a patient receiving diethylstilbestrol for 3 years. In patients receiving these medications, peliosis hepatis should be considered in the differential diagnosis of low attenuation areas in the liver by CT. These patients are subject to increased risk of spontaneous hepatic rupture.

CT of benign soft-tissue masses of the extremities

The computed tomographic (CT) scans and medical records of 35 patients with proven benign soft-tissue masses of the extremities were reviewed to assess the contribution of CT in the evaluation of such masses. CT demonstrated the mass in all 35 cases and was able to provide a specific diagnosis in 28 (80%); 25 prospectively, three retrospectively. Correct diagnoses made using CT included hematomas (five), synovial cysts (seven), myositis ossificans (six), fatty tumors (four), aneurysms (three), pseudoaneurysms (two), schwannoma (one), and abscess (one). The CT appearance of a hematoma depends on its age. Synovial cysts are near-water-density masses, often associated with a small joint effusion. Myositis ossificans can be differentiated from parosteal osteosarcoma by virtue of its characteristic zonal ossification. Lipomas are recognized on noncontrast scans by the characteristic low attenuation of fat, while aneurysms and pseudoaneurysms are best diagnosed on postcontrast scans. In seven cases (20%) a specific diagnosis could not be made on the basis of the CT scan. However, in these cases CT delineated the extent of the mass and demonstrated its relation to surrounding structures; this anatomic information was helpful in planning surgical excision or percutaneous biopsy. The authors conclude that CT is a valuable noninvasive imaging method for the evaluation of soft-tissue masses of the extremities.

Radiologic staging of gastrointestinal neoplasms

In this article, the ability of computed tomography as well as other imaging methods to detect local and distant metastases in patients with either newly diagnosed or suspected recurrent gastrointestinal tumors is discussed. The role of the radiologic examination in the diagnosis of complications resulting from different types of treatment is also addressed.

Gastrohepatic ligament: normal and pathologic CT anatomy

In a review of 200 consecutive CT scans of the upper abdomen, the structures within the gastrohepatic ligament (GHL) were well seen in 182 (91%). In 85% of these 182 patients, the largest structure visible within the GHL was 6 mm or smaller. A total of 27 patients had a structure larger than 6 mm within the GHL; this finding could be explained in 13 by the presence of a normal anatomic variant. Of the 14 others, 12 had known tumor arising in or known to have spread to the upper abdomen. Two patients had no obvious explanation. Fourteen patients with cancers of the stomach (9 patients), pancreas (3 patients), and esophagus (2 patients) had 57 intact nodes that were evaluated pathologically. Of these 40/40 benign nodes and 10/17 malignant nodes were less than or equal to 8 mm in size. When anatomic variants are excluded, the finding of rounded structures greater than 8 mm in the GHL is a reliable indicator of left gastric node involvement by carcinoma or lymphoma or of coronary venous dilatation.

Non-Hodgkin lymphoma: computed tomographic demonstration of unusual extranodal involvement

With the advent of computed tomography, lymphomatous involvement of sites other than lymph nodes is being seen with increasing frequency. Review of computed tomographic scans in 400 patients with newly diagnosed or recurrent non-Hodgkin lymphoma revealed 37 patients to have involvement of 56 unusual sites below the diaphragm: psoas/iliacus muscle (16 patients), kidney (13 patients), pancreas (5 patients), adrenal (4 patients), skin/subcutaneous tissue (4 patients), abdominal wall musculature (4 patients), peritoneum (4 patients), omentum (3 patients), and female reproductive tract (3 patients). These were mostly seen in patients with lymphomas of diffuse architecture, especially diffuse histiocytic lymphoma. Concomitant retroperitoneal and/or mesenteric adenopathy was very common; extranodal involvement was rarely the only site of initial or recurrent lymphoma.

Extralaryngeal causes of vocal cord paralysis: CT evaluation

Computed tomography (CT) was used in 33 patients to evaluate possible extralaryngeal causes of vocal cord paralysis (22 left, 11 right). Neoplasm in the lower neck or upper mediastinum (lung, esophagus, thyroid, breast, lymphoma) was found to be the predominant cause (27/33). A negative CT examination correlated with a neuropathic (e.g., diabetes) or idiopathic etiology. CT proved useful in demonstrating or excluding abnormalities in areas that are difficult to evaluate by physical examination or conventional radiography, particularly the aortopulmonary window. The normal anatomy and pathologic masses involving the recurrent laryngeal nerve are illustrated.

Barium examination of the pharynx after vertical hemilaryngectomy

Vertical hemilaryngectomy (VHL) is an effective treatment for localized true-vocal-cord carcinoma. Single- and double-contrast barium pharyngoesophagrams in 13 post-VHL patients (11 with dysphagia or suspected tumor recurrence, and two asymptomatic volunteers) were reviewed retrospectively. The two asymptomatic volunteers illustrated the normal postoperative appearance, demonstrating an unaltered pharynx, with no barium aspiration. Barium aspiration into the laryngeal vestibule or trachea was seen in 10 cases and was the only abnormal radiographic finding in four such patients. Three instances of tumor recurrence were identified. In two such cases, aspirated barium revealed a narrowed, irregular lumen of the residual laryngeal vestibule with a mass protruding into the subglottic part of the airway. The third example of recurrent malignancy was manifested by a tracheoesophageal fistula. Findings on the barium examination mimicked recurrent tumor in four cases. In one instance, a mound of granulation tissue protruding into the subglottic airway was confused with tumor recurrence. In three cases, the radiographs demonstrated apparent narrowing and mucosal irregularity of the residual laryngeal vestibule. This appearance was due to early postoperative edema or to transient deformity of the pliable residual hemilarynx during deglutition, as shown by videotaped fluoroscopy.

Computed tomography in malignant endometrial neoplasms

Malignant uterine neoplasms are the most common invasive gynecological malignancies. The prognosis depends on the history, the grade, and the stage. Recent reports have stressed that a small percentage of patients with clinically low stage disease have unsuspected metastases. We retrospectively reviewed 61 patients with known malignant uterine neoplasms. In 18 patients with preoperative computed tomographic examinations, these scans detected unsuspected omental metastases in two and pelvic adenopathy in three. There was one false positive and one false negative examination. Computed tomography was superior to the clinical examination in defining the extent of the tumor in five patients. Computed tomography was also helpful in evaluating patients with suspected recurrent disease.

Computed tomographic features of biliary obstruction

A retrospective review of CT scans in 69 consecutive patients with proven biliary obstruction due to both malignant and benign causes was performed to define and differentiate CT changes. Abrupt termination of a dilated extrahepatic biliary duct was characteristic of a malignant process in the absence of a mass. Gradual tapering of a dilated duct was specific for benign disease. Other findings, such as degree of intra- or extrahepatic duct dilatation and presence or absence of a dilated pancreatic duct were not reliable in distinguishing benign from malignant causes. The authors also found CT to be accurate in detecting common duct stones with a sensitivity exceeding 80%.

Computed tomography of laryngoceles

Six patients with laryngoceles, two internal and four of the mixed type, were studied with CT. Uncomplicated laryngoceles appear on CT as air-filled structures lying in the paralaryngeal space (internal), lateral neck (external), or in both locations (mixed). Obstruction of the neck of the laryngocele by either tumor or chronic inflammation can result in a fluid-filled structure, producing on CT a well circumscribed mass of either near water or soft-tissue density, depending on its composition. CT proved useful in establishing the definitive diagnosis of a laryngocele and mapping its total extent for treatment planning.

Compensatory hypertrophy of bone following surgery on the foot

Compensatory hypertrophy of bone developed in 5 patients following surgery on the foot. The typical finding of diffuse cortical thickening of the entire ray is thought to represent a static compensatory response which occurs when the usual dynamic response of altered weight-bearing is inadequate or overridden.

A prospective comparison of the evaluation of biliary obstruction using computed tomography and ultrasonography

A total of 103 consecutive patients with suspected biliary obstruction were studied using both computed tomography (CT) and ultrasound (US) to evaluate the relative accuracy of the methods. In 47 patients with confirmed obstruction, CT and US were comparable accurate in differentiating obstruction from nonobstruction. The precise level of obstruction was identified by CT in 88% and by US in 60%; the cause of obstruction was accurately predicted by CT in 70% and by US in 38%. Both methods detected useful additional information, such as cholelithiasis or retroperitoneal adenopathy. The authors use US as a screening examination; if there is doubt about the level and cause of sonographically demonstrated obstruction, CT has proved to be an accurate means of further evaluation.

Computed tomography of transitional-cell carcinoma of the renal pelvis and ureter

Preoperative staging of transitional-cell carcinoma of the upper urinary tract is important for identification of those tumors amenable to limited resection. Twenty-two patients were examined using computed tomography (CT), and three patterns were noted: (a) a focal intraluminal mass, (b) ureteral wall thickening with luminal narrowing, and (c) an infiltrating mass. In most cases, attenuation was similar to that of soft tissue; one tumor was calcified. Tumors of the renal pelvis may exhibit contrast enhancement. In 11 cases, excretory urography was inadequate or not attempted. CT demonstrated the site and cause of obstruction in all cases and proved to be a useful noninvasive staging procedure for suspected or proved transitional-cell carcinoma of the upper urinary tract.

Natural history of extraperitoneal gas after renal transplantation: CT demonstration

The natural history of extraperitoneal gas present in the operative bed was prospectively evaluated with serial computed tomography in 25 renal transplant patients. While 73% (11/15) of patients studied within the first 4 days after drain removal had residual gas in the operative bed, 90% (9/10) of patients examined after the 5th day had no demonstrable gas in the peritransplant area. Of 12 patients with gas present on the initial scans, follow-up studies documented resolution of the gas in 10 with subsequent benign clinical courses. In the remaining two patients, the gas collections increased in volume on serial examinations followed shortly by wound dehiscence. Our data suggest that gas present later than 1 week following drain removal should prompt careful scrutiny and that an increase in the volume of gas collections on serial studies must be considered pathologic. The incidence and significance of peritransplant fluid collections in these patients are also discussed.

CT of calcified renal masses

The ability to evaluate the composition and to precisely locate calcifications within renal masses resulted in more accurate evaluation of 21 calcified renal masses by computed tomography than by standard radiographic techniques. Of 11 solid tumors, computed tomography demonstrated a soft-tissue mass extending beyond the calcification in nine cases of renal cell carcinoma. Of 10 benign cystic lesions, all six lesions characterized by a uniform water-density center, calcification confined to the wall, and no detectable soft-tissue mass were benign cysts. Three additional cystic lesions (xanthogranulomatous pyelonephritis, multilocular cystic nephroma, and a cyst containing calcified debris) were believed to represent benign lesions prospectively due to the absence of a soft-tissue mass. Only peripherally calcified lesions with a central attenuation higher than accepted for benign cysts were indeterminate by computed tomography. The significance of the computed tomographic findings in terms of malignant potential and patient management is discussed.