Evaluation of aortocoronary bypass graft status by computed tomography.

The efficacy of contrast-enhanced computed tomography to define graft patency status was studied in 42 patients with 100 aortocoronary vein grafts. The status of each graft had been determined earlier by angiography. A rotary fan beam whole body scanner with a 2 second scan duration was used. Initial scans determined the optimal level for study of the graft; patency was assessed by computed tomographic enhancement of the graft after intravenous bolus injection of 30 ml meglumine and sodium diatriazoate. The computed tomographic studies were evaluated without knowledge of the angiographic findings; graft status by computed tomography was interpreted as patent, occluded or equivocal. Overall, computed tomography correctly defined graft patency status in 79 of the 100 grafts and incorrectly identified it in 9; in 12 grafts, the computed tomographic diagnosis was equivocal. Computed tomography correctly identified 61 of 74 patent grafts and 18 of 26 occluded grafts. Patency status was correctly defined by computed tomography in 35 of 37 grafts to the left anterior descending artery, 23 of 30 grafts to circumflex branches and 19 of 31 grafts to the right coronary artery. These data indicate that computed tomography is a promising noninvasive method of determining patency of aortocoronary bypass grafts, especially of grafts to the left anterior descending artery.

CT features of renal cell carcinoma with emphasis on relation to tumor size.

Computed tomography (CT) is the current standard for diagnosing and staging renal cell carcinoma (RCC). Although general diagnostic guidelines exist, no large studies to date have delineated the CT features of RCC. We reviewed the CT appearances of 78 pathologically proven RCCs. Of the 61 RCCs larger than 50 mm (78%) there was imaging evidence of extrarenal spread (87%), intratumoral necrosis (61%) and differential growth rates within the tumor (64%). Tumors 50 mm or smaller often had a "benign" appearance with sharp, rounded margins (88%), homogeneous density (65%), and distinct interface with the kidney (82%). The significance of these lesions should not be underestimated. Although RCCs often showed transient marked enhancement after bolus contrast material injection (41%), during the infusion phase 97% were hypodense compared with the kidney regardless of tumor size. Calcifications were visible in 31% of RCCs. Although 22% of RCCs were predominantly cystic, none fulfilled all CT criteria of simple renal cysts.

Computed tomography for evaluation of mediastinal lymph nodes in lung cancer: correlation with surgical staging.

Computed tomography (CT) of the chest (late model) was done preoperatively in 56 candidates for resection of lung cancer. Precise borders for each node region were defined by the American Thoracic Society modification of the classification of the American Joint Committee for Cancer Staging and were used to "map" nodes seen on CT and nodes removed surgically. Metastatic involvement of mediastinal nodes was proven by mediastinoscopy in 11 patients; nodes were removed from multiple regions at thoracotomy in 45 patients. The mediastinum was clearly delineated by CT in 46 patients with determinate scans and was judged normal in 32 (CT-negative scans) and abnormal in 14 (CT-positive scans). A node was considered metastatically involved if it measured greater than 1.5 cm in diameter. Positive nodes were found at surgical staging in 3 of 32 patients with CT-negative scans and in all patients with CT-positive scans. Thus, for the 46 patients with determinate scans, sensitivity was 82%, specificity was 100%, and accuracy (true positive and true negative) was 93%. The high accuracy of CT in these patients suggests that mediastinoscopy is not necessary before thoracotomy in the patient with a CT-negative scan, but that for the patient with a CT-positive or CT-indeterminate scan, the indications for mediastinoscopy remain the same.

Esophageal cancer. Radiologic staging.

Multimodality therapy is used in patients with esophageal cancer because accurate tumor staging is essential to determine whether treatment should be directed toward cure or palliation. Imaging strategies must not only include tumor visualization but also incorporate pretreatment staging as the most important objective. This article reviews the use of CT scans, endoscopic ultrasound, and barium studies in the staging of esophageal cancer.

Esophageal squamous carcinoma.

Squamous cell carcinoma of the esophagus is a tumor with poor prognosis; it is usually in an advanced state when first diagnosed. Because a multimodal treatment approach is currently used, proper tumor staging is essential to determine whether therapy should be directed toward cure or palliation. Important prognostic features of squamous cell carcinoma include the depth of tumor infiltration into or through the esophageal wall and the presence of distant metastases. Imaging strategies should not be limited to visualization of the tumor but also should be directed toward accurate pretreatment staging. In this article, the authors review the use of barium swallow, CT scans, and endoscopic ultrasonography both alone and in combination to visualize and stage esophageal carcinoma. The strengths and limitations of each modality are also discussed.

Nuclear magnetic resonance imaging.

Nuclear magnetic resonance imaging has reached the point at which it is clear that such images will have a definite role in clinical practice. This article reviews the basic physical principles of nuclear magnetic resonance imaging, its current uses in disorders of the central nervous system, and its potential future applications in this field. The technique is also compared with computed tomography and positron emission tomography. Because nuclear magnetic resonance imaging is still in its infancy and its potential is great, definitive statements on present clinical use are difficult. Continual change and expansion of the role of nuclear magnetic resonance imaging in clinical practice in the next few years should be the rule.

Inverted Meckel's diverticulum.

Although Meckel's diverticulum is a relatively common anomaly, inverted Meckel's diverticulum has been reported rarely. We describe a 59-year-old woman with inverted Meckel's diverticulum located at the distal ileum simulating a benign tumor. Computed tomography showed a small mass with a central area of low fat density, and appearance not described previously.

Computed tomography evaluation of colorectal carcinoma.

Knowledge of the extent of primary colorectal carcinoma at initial diagnosis is critical for proper management of disease. Currently, CT does not have a role in screening for colorectal carcinoma, though promising work on virtual colonoscopy is on the horizon. In patients with proven colorectal carcinoma, accurate prospective noninvasive assessment can identify those who may benefit from preoperative local radiotherapy, hepatic resection or cryoablation, or intra-arterial chemotherapy. CT should be considered complementary to the clinical assessment of colorectal carcinoma and to other modalities, such as barium enema, endorectal ultrasonography, MRI, and immunoscintigraphy. Although limited in evaluation of the primary tumor and local spread, CT has proven useful in assessing patients thought to harbor extensive local or metastatic disease. CT is generally the modality of choice for imaging the postoperative patient. The cross-sectional display of CT clearly depicts the operative bed, particularly after abdominoperineal resection. Baseline examinations should be obtained 2 to 4 months after surgery, with follow-up examinations every 6 to 9 months for 2 years, and yearly studies thereafter. CT-guided biopsies should be performed when findings suggest recurrent carcinoma.

The use of coronal sections in evaluating lesions of the sellar and parasellar regions.

Nine cases from a series of 12 are presented to illustrate the value of coronal sections in delineating the borders and origins of extraaxial sellar and parasellar masses. In this projection, the presence or absence of suprasellar extension is demonstrated, and two important signs are discussed. A rim of cisternal cerebrospinal fluid termed the "cap" is seen over the superior border of masses extending into the suprasellar region defining their extraaxial location. The broad base of a lesion will define its origin. The limitations of the method are also discussed.

Ultrasonic characteristics of pancreatic tumors.

The ultrasonic features of 40 pancreatic tumors were analyzed. The tumors were categorized by texture, attenuation, shape, size, and location. Secondary effects of pancreatic duct visualization, biliary stasis, splenic vein involvement, metastases, and ascites were reviewed. Thirty of thrity-one adenocarcinomas had a similar ultrasonic texture consisting of a background of faint, low-level echoes with varying amounts of superimposed coarse echoes. Tumors are detectable prior to enlargement or distortion of the pancreas. Secondary features were present in 94% of the adenocarcinomas. Significant information regarding the possibility and complexity of resection can be provided.

The fluid-filled stomach: a new sonic window.

Gastric air and peristalsis usually are obstacles to ultrasound imaging of the tail of the pancreas. Fifteen normal volunteers were scanned transversely in the supine position before and after intravenous administration of glucagon (1 mg) and oral administration of water. In 13 of 15 subjects glucagon produced a dilated gastric fundus that retained fluid for 30--60 min, thus allowing good imaging of the pancreatic tail in 10 subjects and fair imaging in 2 subjects. This method of creating a gastric sonic window should prove to be valuable in ultrasound imaging of the pancreas.

MR appearance of sternal hyperostosis.

Sternal hyperostosis is characterized by prominent new bone formation and fibrosis with less pronounced areas of granulation tissue and round cell infiltration. In previously reported cases the process involved not only the sternum but adjacent bony areas as well. Depending upon the extent of disease, acquiring biopsy material for histologic analysis can be difficult. We report a case of sternal hyperostosis involving the sternum exclusively and extensively. Magnetic resonance imaging was useful in directing biopsy for optimal histologic yield. This unusual case of sternal hyperostosis is believed to be the result of an inflammatory process.

Pleomorphic carcinoma of the pancreas: computed-tomographic, sonographic, and pathologic findings.

We present a series of eight cases of pleomorphic carcinoma of the pancreas, an uncommon lesion that contains bizarre giant cells and resembles sarcoma histologically. To our knowledge, this entity has not been described in the radiological literature. Clinical symptoms are similar to those of the usual pancreatic ductal cell carcinoma, but at presentation the primary tumor mass is usually large, and widespread metastatic disease is present. The most striking finding is massive lymphadenopathy, which may mimic lymphoma. A combination of clinical history, imaging findings, and results of percutaneous biopsy should lead to the proper diagnosis and may help to differentiate this entity from others that may affect lymph nodes.

Pancreatitis: an important cause of abdominal symptoms in patients on peritoneal dialysis.

In an eight-month period, four patients in our peritoneal dialysis program developed acute pancreatitis, an incidence significantly higher than that in our hemodialysis program. Diagnosis was difficult since the symptoms of pancreatitis were similar to those of peritoneal dialysis-associated peritonitis. Further difficulties in diagnosis were due to unreliability of serum amylase levels and "routine" ultrasound examinations in suggesting the presence of pancreatitis. Computerized tomography performed in three patients showed enlarged, edematous pancreata with large extrapancreatic fluid collections in all cases. Two patients died, one directly due to complications of pancreatitis. One patient was changed to hemodialysis and showed clinical and radiologic resolution of his pancreatitis. One patient remains on peritoneal dialysis but has now had four attacks of acute pancreatitis. No patient had classic risk factors for development of pancreatitis. Review of patient histories showed no common historical factors except for renal failure itself, peritoneal dialysis, peritonitis, catheter surgery, and hypoproteinemia. It is possible that metabolic abnormalities related to absorption of glucose and buffer from dialysate or absorption of a toxic substance present in dialysate, bags, or tubing can cause pancreatitis in patients on peritoneal dialysis. We feel that a diagnosis of pancreatitis should be considered when peritoneal dialysis patients present with abdominal pain, particularly if peritoneal fluid cultures are negative or if patients with positive cultures do not have prompt resolution of symptoms with appropriate antibiotic therapy.

Evaluation of PACS in ultrasonography.

We review our experience with a picture archiving and communication system to replace film in the ultrasound section of a clinical radiology department. The system includes three ultrasound units connected by a fiberoptic network via acquisition nodes to a central data management system, workstation, and optical jukebox. The system handles 80% of sonographic studies in the department. Image production, interpretation, storage, and retrieval are evaluated. Despite limitations, a picture archiving and communication system can be integrated into a functioning ultrasound section of an active radiology department with minimal disruption and promising results.

Renal sinus histiocytosis.

A 26-year-old woman had an infiltrative renal lesion accompanied by massive regional lymphadenopathy. Biopsy of the renal mass and a coexistent orbital mass revealed identical histologic evidence of sinus histiocytosis. This unusual benign entity is uncommon in the kidney, but radiographically, it may closely simulate an infiltrative renal neoplasm, especially a lymphoma or leukemia or even renal cell carcinoma.