John R. Haaga

Urological applications of computerized axial tomography: a preliminary report.

Computerized tomography scanning of the chest and abdomen has been used as a diagnostic technique in more than 4,500 patients since 1974, 190 of whom had histologically proved disorders of the genitourinary system and retroperitoneum. On the basis of this experience computerized tomography scanning has been found to be safe and effective, and offers certain advantages over conventional techniques. The number, extent and content of renal mass lesions can be determined with relatively great accuracy. The presence and extent of metastases into the retroperitoneum, liver and chest can often be shown by computerized tomography scanning when other tests are negative. Placement of needles for aspiration, biopsy, injection of contrast medium or insertion of drainage tubes can be done more accurately under computerized tomography control. Computerized tomography in itself is non-invasive, carries a low radiation exposure comparable to other radiographic procedures and therefore, can be valuable in following the course of patients with various diseases during and after therapy. While scanning will not replace other diagnostic procedures it should lead to a more judicious selection of potentially hazardous tests in selected cases, such as angiography, aspiration and open biopsy.

Gated computed tomography of the heart

Since the inception of computed tomography (CT), we have been keenly interested in the possibility of imaging the myocardium in the axial dimension in vivo. Initial efforts at quantitive myocardial imaging were of necessity performed in vitro in the original EMI brain scanner (1). Combined with a study of whole blood in vitro, it became apparent that individuals with a normal hematocrit.would not show a significant difference between the density of the myocardium and blood without the use of a contrast agent. To study the myocardium in vivo would require either an ultrashort scan period (less than S0 msec (2)) or data acquisition at synchronized periods during the heart cycle (gating). With the advent of faster scan cycles in currently available commercial equipment, the initial thrust at in vivo myocardial imaging became possible. The potential advantages of myocardial imaging are numerous and include the ability to differentiate the myocardium from the blood pool which would permit volume analysis, determination of ejection fraction, study of akinesis and dyskinesis, evaluation of ischemic myocardium and, ultimately, the visualization of the lumen of coronary arteries. A noncatheter, low risk technique which could accurately portray the lumina of coronary arteries would be of inestimable public health value. The technologic considerations involved in achieving this task are, however, formidable. The history of scanning of the heart is brief but relevant. The myocardium has been imaged by CT in vivo since the advent of CT body scanning (3). Because early scanners required 60 to 180 traverses and the total scan took from 2 to 7 rain, the image of the myocardium was necessarily one that averaged during multiple cardiac contractions. The chamber wall, blood pool, fat surrounding the myocardium as well as the pericardium, septa and valves were not resolved because of systolic-diastolic motion blurring. The image was further degraded by respiratory motion (2). In addition, artifacts were created by cardiac pulsations transmitted to the high density diaphragm and subjacent structures which interface with the low density lung parenchyma. Clearly, an approach was needed wherein the subject would be apneic and the cardiac structures could be imaged in fractions of a second. Wood (4) and Ritman et al (5) were first to propose a cardiac scanning device with a multiple x-ray tube-detector array to scan the myocardium in fractions of a second. To date, such a device remains theoretically possible; however, it has not been accomplished in the laboratory. In vitro investigations of myocardial perfusion by Adams et al (6) are reported to show minute differences in attenuation coefficients of recently infarcted myocardium. In other experiments, Aifidi et al (2) and Ter-Pogossian et al (7) showed that CT angiocardiography using positive contrast agents was feasible in intact sacrlfi~:ed animals.

The floating aorta in computerized tomography: A sign of retroperitoneal pathology

Abstract The diagnosis of retroperitoneal disease including mass lesions has been a difficult one to make in the past and many conventional radiologic modes, including arteriography, ultrasonography, excretory urography and lymphangiography, have been used. A reliable sign of retroperitoneal pathology is anterior displacement of the abdominal aorta which was previously described utilizing lateral roentgenology (1), arteriography, (2) and ultrasonography (3).

Pseudocyst of the pancreas with perirenal extension: Demonstration by computed tomography

Abstract An uncommon case of a patient with a pseudocyst of the pancreas clinically mimicking a renal mass is demonstrated by CT including the extent of dissection. Once the cyst in the pancreas was known, other radiographic methods helped to confirm the diagnosis. A review of the literature concerning pseudocyst extension to the kidney is also presented.

Foreign body localization and removal utilizing computerized axial tomography

In this preliminary report, computerized tomography guidance was instrumental in allowing the safe and rapid removal of a metallic foreign body from paravesical soft tissues deep within the male pelvis. Hopefully, expanded future experience with this technique will further clarify its value in the management of retained foreign bodies.

Computerized tomography-guided percutaneous transhepatic biliary drainage

Abstract With the introduction of computed tomography (CT) of the body, an excellent cross-sectional image display of the various organ systems within the abdomen became available. As a result, it soon became apparent that with the use of computed tomography percutaneous aspiration biopsies could be facilitated (1). Using computed tomography guidance it is now possible to accurately place a biopsy instrument within virtually any organ in the abdomen. CT-guided needle procedures are useful not only for the purpose of diagnosis, but are valuable as a therapeutic tool in selective patients. We wish to describe a method of computed tomography-guided percutaneous transhepatic biliary drainage which we have utilized in five patients to accomplish definitive relief of obstructed biliary systems. Each of our patients had an inoperable carcinoma either in the head of the pancreas or in the region of the porta hepatis which resulted in obstruction of the biliary system.