Arvis G. Williams

CT appearance of a surgically retained towel (Gossypiboma)

A case of a surgically retained towel within the peritoneal space is reported. Computed tomography demonstrated an unusual appearance not unlike that previously described for retained surgical sponges. Computed tomography of the gastrointestinal tract served as a useful adjunct to barium radiography in this case, suggesting the correct diagnosis of foreign body.

Population characteristics and absorbed dose to the population from nuclear medicine: United States--1982.

Those in the U.S. population who receive nuclear medicine examinations have been characterized by age and sex. Males received 42% of examinations while females received 58%. More than one-third of the examinations were done on persons older than 64 y of age and more than two-thirds on patients older than 45 y of age. The per caput effective dose equivalent from nuclear medicine procedures in 1982 was 140 muSv (14 mrem); whereas, the per caput age-specific effective dose equivalent to the U.S. population was 50 muSv (5.9 mrem). These can be compared with 2 mSv (200 mrem) from natural background.

Analytical modeling of worldwide medical radiation use

An analytical model was developed to estimate the availability and frequency of medical radiation use on a worldwide basis. This model includes medical and dental x-ray, nuclear medicine, and radiation therapy. The development of an analytical model is necessary as the first step in estimating the radiation dose to the worlds population from this source. Since there is no data about the frequency of medical radiation use in more than half the countries in the world and only fragmentary data in an additional one-fourth of the worlds countries, such a model can be used to predict the uses of medical radiation in these countries. The model indicates that there are approximately 400,000 medical x-ray machines worldwide and that approximately 1.2 billion diagnostic medical x-ray examinations are performed annually. Dental x-ray examinations are estimated at 315 million annually and approximately 22 million in-vivo diagnostic nuclear medicine examinations. Approximately 4 million radiation therapy procedures or courses of treatment are undertaken annually.

Tc-99m PYP scanning following low voltage electrical injury.

An adolescent boy sustained low voltage electrical injury to his extremities when he inadvertently touched a low tension (440 volts) wire with a metal tube. Early in his hospital course, he was evaluated with Tc–99m pyrophosphate whole body scanning for the extent of his injuries. The scintigraphic findings correlated well with his subsequent clinical course.

Intraspinal, extradural ependymoma.

Extradural ependymoma is a rare tumor arising most commonly in the soft tissues of the presacral area, less commonly in the soft tissues of the sacrococcygeal region dorsal to the sacrum, and rarely in the extradural portion of the spinal canal. The differential diagnosis varies with the location, but the natural history of the tumor is the same. If the tumor is not completely excised at surgery, it may recur. Distant metastases have been reported. A case of an extradural ependymoma arising within the spinal canal is reported with myelographic and computed tomographic findings at diagnosis and after therapy.

Intrathoracic kidney on radionuclide renography. A case report.

A child with an asymptomatic mass in the lower right thorax was evaluated with sonography, intravenous urography, and radionuclide renography. High renal ectopia was only diagnosed with radionuclide renography.

Sulfur colloid distribution in normal hips.

The normal distribution of Tc-99m sulfur colloid is described in 100 patients with no clinical or radiographic evidence of hip disorders. Two-thirds of the patients had uptake in the femoral neck and some uptake in the femoral head. In the other one-third, no uptake was detected in either femoral head. A high degree of symmetry was noted. Judging both the symmetry and pattern of uptake in both hips is important in evaluating femoral head vasculature after a fracture.

The insensitivity of 99mTc pertechnetate imaging for kaposi's sarcoma

A total of 13 technetium 99m (99mTc) pertechnetate image studies were performed on 7 patients with a histologic diagnosis of Kaposis sarcoma. Five patients with peripheral edema had diffusely increased radionuclide activity in the same areas. The two patients without edema had normal radionuclide images. The primary cutaneous lesions were only identified in one of the patients. These findings suggest that previously reported “occult metastasis” are probably due to peripheral edema in most patients; therefore, the radionuclide study has a much lower sensitivity than has been previously reported.

Comparison Of Modulation Transfer Function (MTF) And Contrast Detail Image Evaluation Tests

An evaluation of imaging systems with different resolutions was made using MTF and Contrast Detail observer performance studies. The different imaging characteristics were obtained by changing the collimator in a clinical gamma camera. Three collimators were used. The two evaluation tests (MTF and CD) agreed on the relative ranking of the image systems. We conclude that contrast detail tests are useful in spite of their shortcomings.

Ascites causing a false-positive radionuclide liver image

False-positive radionuclide liver images can occur due to impingement on the liver by adjacent normal anatomic structures or adjacent pathologic masses or fluid collections. A patient with ascites in the anterior subphrenic space had an apparent “cold” lesion in the left lobe of the liver. Ultrasonography demonstrated a normal left lobe and localized the fluid collection.