Biomedical subjects
Publications and source records attributed to M R Conrad.
Three unusual cases of pancreatic pseudocyst are described in which primary renal or splenic pathology was simulated on ultrasound imaging. When an abnormal fluid collection is imaged in a patient with a history of alcoholism, a pancreatic pseudocyst should be considered and an amylase determination should be obtained on any aspirated fluid.
The criteria for the diagnosis of minimal obstructive jaundice (i.e., bilirubin less than 11.0 mg/100 ml) using sonography have not been established. A reliable diagnosis of obstructive jaundice with mild dilation of the bile ducts can be made by sonography when the "parallel channel" sign is seen. This sign is due to the simultaneous imaging of the dilated right or left main hepatic duct and the adjacent contiguous main portal vein branch. A prospective study of 86 patients showed this to be a highly reliable means of differentiating obstructive from nonobstructive jaundice when minimal duct dilation is present.
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The pelvicalyceal echo complex has a characteristic appearance as an echo-filled cylinder in which minimal sonolucency may normally be seen. Alteration in the pelvicalyceal echo complex is a helpful guide in the diagnosis of a variety of pathological processes involving the kidneys. Reliable diagnosis of moderate and marked hydronephrosis may be made by the appearance of uniformly sized, sonolucent collections in the pelvicalyceal echo complex which show communication with the renal pelvis. An adjacent simple renal cyst produces a sharply defined crescent shaped deformity of the pelvicalyceal echo complex, and scalloping is seen with multiple impinging renal cysts. Gross deformity of the central echo complex is seen with polycystic kidney disease, as well as in neoplasia. Edema and infiltrating hypernephroma may result in diminution of the pelvicalyceal echo complex. Amputation or a "V"-shaped splitting of the pelvicalyceal echo complex may be seen with neoplasia.
When a tracheal-innominate artery fistula is suspected, angiography is essential if the patient's condition is stable. An aggressive angiographic approach is needed to demonstrate the fistulous tract. Multiple injections in different degrees of obliquity and subtraction views should be obtained for early accurate diagnosis and for optimal demonstration of the pathologic anatomy.
A perinephric is difficult to diagnose by clinical examination and traditional radiographic imaging techniques. Five cases are described in which the sonograms revealed a sonolucent perinephric collection suggestive of perinephric abscess. Diagnostic percutaneous aspiration performed under ultrasound guidance is a rapid, reliable, and safe means of distinguishing an abscess from a noninflammatory collection.
Recent B-scan ultrasonic techniques have made possible the routine visualization of the major upper abdominal venous structures. Real-time scanning permits in vivo dynamic assessment of the upper abdominal veins. B-scan ultrasound allows optimal anatomic resolution and is superior for the establishment of intraluminal pathology and anatomic relationships with adjacent organs. The anatomic localization of the upper abdominal veins has proved of practical importance in several ways. Identification of the splenic and superior mesenteric veins allows localization of the pancreas and the enlarged common bile duct. Increased size of the upper abdominal venous structures can indicate certain pathological conditions, notably raised right heart pressure and portal hypertension. Intrinsic pathology within the inferior vena cava may be detected. Extrinsic distortion of veins by adjacent mass lesions is not uncommon, and if the venous structure is recognized, more precise anatomic localization of the mass is possible.
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The recent introduction of gray scale ultrasound, which uses a higher power output, has made it more difficult ot assess the cystic or solid nature of sonolucent mass lesions using the cirteria developed for bistable imaging, i.e. the amount of through transmission and the strength of the posterior wall echo. However, a cyst may be reliably diagnosed if a totally echofree area is seen adjacent to an area with low-level echoes derived from tissue parenchyma. We have termed this the "light bulb sign." Visualization of the sign facilitates the decision of the optimal time for abscess drainage.
We used sonography to investigate 3 patients with hypertension owing to a Page kidney phenomenon. In 2 cases a perinephric cystic collection was compressing the kidney, while in 1 case there was a large perinephric organized hematoma. When a Page kidney is suspected in a hypertensive patient sonography is a reasonable next step in the evaluation, after the excretory urogram, and may obviate the need for angiography.
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