Biomedical subjects
Publications and source records attributed to W H McCartney.
We present a case in which dramatic anterior midline uptake of 99mTc-pertechnetate simulated a suprasellar tumor in a patient with sarcoid. The brain scan abnormalities proved to represent extensive hypothalamic and basal ganglia involvement by sarcoidosis.
Various combinations of window settings and displays were evaluated to determine the optimal photographic reproduction of images obtained from the Ohio-Nuclear Delta scanner to best demonstrate bony structure by computed tomography. A combination of wide window and negative images will produce better bony structure detail than various other settings. The physical basis of this technique will be described along with several cases to illustrate the conclusion. Although no one combination was universally adequate, the best in our experience was a wide window with negative images.
The radionuclide liver scan is a valuable study for detection of hepatic metastases; however, it has a false-negative rate of between 10 and 30%. In a double-blind study involving 377 patients, we assessed the value of CEA assay as an adjunct to liver scanning for detection of hepatic metastases. Fifty-seven patients studied by both methods were ultimately proven to have liver metastases. All patients with CEA levels above 9 ng/ml and focal defects on liver scan had hepatic tumor involvement, while only 4 of 291 patients with CEA values less than 9 ng/ml and negative scans were later shown to have liver metastases. CEA and liver scan results were discordant for 29 patients with proven hepatic metastases: the radionuclide study was positive in 21 cases with false-negative CEA results, while the CEA assay suggested the presence of metastatic disease in eight of the 12 patients with false-negative liver scans.
Gallium 67 has been found to be extremely useful for detection of inflammatory disease. In the skeletal system it complements the 99m Tc-phosphate compounds in differentiating periatricular osteomyelitis, septic arthritis, and cellulitis. Gallium is particularly useful in documenting successful treatment of bone infection because the phosphate scan remains positive for much longer periods of time. In a variety of chest disorders gallium uptake has been found to correlate well with the active inflammatory state. One of the most frequent uses of gallium imaging has been for localization of inflammatory foci in postoperative patients as well as in patients who present with fever of undetermined origin. Neutrophilic labeling followed by migration to the inflammatory area appears to be the major mechanism of localization of radiogallium. For this reason leukopenic patients constitute a group in which false negative results may be encountered.
Forty-two patients suspected of having stress fractures were evaluated by serial roentgenograms and by one total-body scan with detailed views of suspicious areas. Stress fracture was the ultimate clinical diagnosis in twenty-one patients, and in fifteen of them the roentgenograms were normal while the scintigram was positive. The false negative rate for the roentgenograms was 71 per cent. In eleven of the fifteen patients, the roentgenograms eventually became positive. There were five positive scintigrams from causes other than stress fracture, giving a false positive rate for scintigraphy of 24 per cent. The bones with stress fractures included the metatarsals, calcaneus, tibia, femur, and fibula.
In a double-blind study involving 377 patients, we assessed the value of the serum carcinoembryonic antigen (CEA) assay as an adjunct to the radionuclide liver scan for detection of liver metastases. Fifty-seven patients studied by both methods were ultimately proved to have liver metastases. In 28 instances in which the results of both tests were in agreement, these results were diagnostic with regard to presence or absence of hepatic involvement. The CEA assay suggested the presence of metastatic tumor in eight of the 12 patients with false-negative liver scans, thus proving to be a very useful adjunct to liver scanning in the detection of hepatic metastasis.
Explore the source record for details and available documents.
A 15-year-old primigravida with severe preeclampsia at term developed blindness. Following delivery by cesarean section, her visual acuity returned promptly. Computerized tomography demonstrated bilateral cerebral lesions in the occipital cortex, which resolved partially by five days and completely by seven months after delivery. Persistent electroencephalogram abnormalities and transient episodes of blindness suggest the presence of residual cerebral damage.
In recent years, there has been much interest in the clinical application of attenuation compensation to myocardial perfusion single photon emission computed tomography (SPECT) with the promise that accurate quantitative images can be obtained to improve clinical diagnoses. The different attenuation compensation methods that are available create confusion and some misconceptions. Also, attenuation-compensated images reveal other image-degrading effects including collimator-detector blurring and scatter that are not apparent in uncompensated images. This article presents basic concepts of the major factors that degrade the quality and quantitative accuracy of myocardial perfusion SPECT images, and includes a discussion of the various image reconstruction and compensation methods and misconceptions and pitfalls in implementation. The differences between the various compensation methods and their performance are demonstrated. Particular emphasis is directed to an approach that promises to provide quantitative myocardial perfusion SPECT images by accurately compensating for the 3-dimensional (3-D) attenuation, collimator-detector response, and scatter effects. With advances in the computer hardware and optimized implementation techniques, quantitatively accurate and high-quality myocardial perfusion SPECT images can be obtained in clinically acceptable processing time. Examples from simulation, phantom, and patient studies are used to demonstrate the various aspects of the investigation. We conclude that quantitative myocardial perfusion SPECT, which holds great promise to improve clinical diagnosis, is an achievable goal in the near future.
Gadolinium-diethylenetriamine pentaacetic acid (DTPA) enhancement of radiation-induced apical pulmonary fibrosis was observed in two patients previously treated for breast cancer. In one case the fibrosis was biopsied twice, with no change in its CT appearance over 3 years. Gadolinium-DTPA may enhance benign apical fibrosis after radiation therapy and should not, in and of itself, be used as evidence of recurrent malignancy.