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Biomedical subjects

A Dwyer

Publications and source records attributed to A Dwyer.

33 records · Page 2Linked to original sources
PubMed1985

Detection of pulmonary metastases in patients with osteogenic and soft-tissue sarcomas: the superiority of CT scans compared with conventional linear tomograms using dynamic analysis.

A prospective serial evaluation in 19 patients with soft-tissue and osteogenic sarcomas was performed to determine whether computerized tomography (CT) or conventional linear tomography (LT) detected pulmonary metastases earlier. Analysis of the metastatic nodules was performed radiographically with histologic confirmation by obtaining serial CTs and LTs followed by metastasectomy. Nodules were classified as stable, growing, or developing and by detection on CT and/or LT. CT was the first positive study in a significantly greater number of patients (13 CT, 1 LT; P less than .005), and CT detected the nodules earlier than LT (56 CT first v 7 LT first; P less than .0001). Ninety of 166 nodules resected were detected by CT, LT, or both (54%). The median size of metastatic nodules documented at surgical exploration and first detected by CT was significantly smaller than that first detected by LT (7.6 mm for CT v 13.2 mm for LT; P less than .05). Of 55 histologically documented metastases detected initially either by CT or LT, CT was markedly superior to LT with 50 (91%) first detected only by CT (P less than .001). These data reveal that CT detects more pulmonary metastases earlier than LT and that developing or growing nodules in patients with sarcomas are usually metastases. Decisions regarding metastasis resection in sarcoma patients, therefore, should be based primarily on CT findings.

Adolescent↗
PubMed1984

Prospective studies of laboratory and radiologic tests in the management of colon and rectal cancer patients: I. Selection of useful preoperative tests through an analysis of surgically occult metastases.

The laboratory and radiologic tests that give useful information in colon and rectal cancer patients over and above that obtained by routine work-up and surgical exploration of the abdomen have not been defined previously. An analysis of surgically occult metastases was used to discover which test would assist in the management of these patients. Occult metastases for radiologic tests were those occurring within one year after resection of the primary tumor; for CEA they were metastases occurring at any time following surgery. Full lung tomography, liver/spleen scan, computerized tomogram of the abdomen, intravenous pyelogram, bone scan, and postoperative baseline CEA greater than 2.5 ng/ml were analyzed. The postoperative baseline CEA was the most sensitive test detecting occult metastases in 57 per cent (12 out of 21) of a high risk patient population. Both postoperative baseline CEA and computerized tomograms of the abdomen had high positive predictive values of 71 and 67 per cent. The negative predictive percentage of computerized tomograms of the abdomen (18 per cent) was lower than that of CEA (21 per cent). In comparing these tests in individual patients with occult recurrence, postoperative CEA and computerized tomograms of the abdomen were seen to be complementary in that approximately 90 per cent of occult metastases were detected when both examinations were used. Computerized tomogram of the abdomen and postoperative baseline CEA are useful in patients with primary colorectal cancer as part of their routine work-up.

Carcinoembryonic Antigen↗
PubMed1984

Segmental hyperlucent defects in the liver.

When lucent defects in the liver have a segmental configuration, they may be on an ischemic basis and related to decreased vascular perfusion. Portal venous inflow, by virtue of its low pressure, is particularly susceptible to diversion by focal intrahepatic masses, intravenous thrombi, or external compression. Innovative operative techniques for tumor enucleation may also result in lucent defects that can be confused with, or conceal, pathology. A hypothesis relating such defects to diminished portal inflow and reduced glycogen content is proposed.

Female↗
PubMed1984

Isosignal contours and signal gradients as an aid to choosing MR imaging techniques.

The signal strength of a magnetic resonance (MR) image depends on a variety of factors, including the tissue properties of proton density (p) and relaxation times (T1 and T2) and the scanning sequence. Given this complex interrelation of factors, a graphic method of displaying the image intensity for various tissue properties is needed. In this paper we use isosignal contour curves to display "topographically" the relationships of signal intensity to the tissue properties of p, T1, and T2 for a variety of operator settings in the techniques of saturation recovery, inversion recovery, and spin echo. We further demonstrate the utility of these curves in explaining image appearances and in choosing appropriate pulse sequences for imaging.

Brain Stem↗
PubMed1983

Influence of glycogen on liver density: computed tomography from a metabolic perspective.

The liver is a metabolically active organ with a radiographic density that can be modified by its glycogen and fat content. In rhesus monkeys an increase in liver glycogen induced by glucose loading was accompanied by an increase in attenuation values on computed tomography and a decrease in total liver fat. Conversely, fasting depleted glycogen, increased fat, and decreased liver attenuation. Acute glycogen depletion without significant change in fat was induced by administration of glucagon and accompanied by a decrease in attenuation. These results along with in vitro measurements of glycogen solutions suggest that an increase of approximately 3 Hounsfield units can be expected for each percent increase in liver glycogen content.

Absorptiometry, Photon↗
PubMed1982

Small-cell osteosarcoma.

Six cases of small-cell osteosarcoma, a tumor that resembles Ewing's sarcoma but produces osteoid matrix, are presented. The patients were young (6-31 years of age) and presented with symptoms of pain and/or swelling of 1-10 months duration. The lesions demonstrated a wide variation in radiographic appearance. Histologically, the tumors were composed of small, round cells that produced variable amounts of osteoid. In three cases chondroid was also present. Two of the six patients were treated with surgery alone and four received radiation and either single- or multiple-agent adjuvant chemotherapy. The two patients who received radiation and multiple-agent adjuvant chemotherapy have no evidence of disease at four and ten years after diagnosis. Recognition of this tumor as distinct from Ewing's sarcoma and from other forms of osteosarcoma is important to determine the incidence, clinical features, and optimal therapy for this tumor.

Adolescent↗
PubMed1980

Evaluation of bupivacaine nerve blocks in the modification of pain and pulmonary function changes after thoracotomy.

Thirty-one patients undergoing thoracotomy were prospectively randomized to receive (1) no nerve blocks (n = 12), (2) placement of percutaneous catheters for intermittent nerve blocks with bupivacaine (Marcaine) (n = 10), or (3) bupivacaine nerve blocks intraoperatively (n = 8). One patient refused postoperative evaluation and was not included in this study. All patients received similar preoperative, intraoperative, and postoperative medications. Comparison of preoperative and postoperative arterial blood gases, assessments of pain and alertness, and chest roentgenograms showed no statistical advantage for any group. Analgesic requirements and pulmonary functions (functional residual capacity, tidal volume, minute ventilation peak flow, or forced expiratory volume) did not differ among the groups. Statistically significant differences were seen in mean respiratory rate and forced vital capacity. These differences, however, indicate that bupivacaine either by intraoperative use or by intermittent percutaneous administration did not improve postoperative increases in respiratory rate or decreases in forced vital capacity.

Bupivacaine↗
PubMed1978

The displaced crus: a sign for distinguishing between pleural fluid and ascites on computed tomography.

Fluid collections in the lower pleural cavity and upper abdominal cavity may sometimes appear similar on computed tomography. Lateral displacement of the diaphragmatic crus and interposition of fluid between the crus and vertebral column indicate an intrapleural component. Demonstration of fluid anterior to the crus establishes an intraperitoneal component. Medial location of the posterior recess of the fluid collection and the intercostal bulging of its lateral margin suggest a pleural effusion.

Ascites↗
PubMed1976

Radionuclide determination of cardiac chamber flow/volume characteristics.

The flow/volume characteristics of an externally monitored radionuclide dilution curve may contain valuable information about specific cardiac chamber abnormalities. a simplified method of obtaining this flow/volume ratio on a standard scintillation camera is presented. Preliminary clinical application to right-sided cardiac lesions has been undertaken. The implications of flow/volume variation with time are discussed.

Cardiac Volume↗
PubMedDate not supplied

Ultrasonic evaluation of therapeutic response in tumors: its values and implications.

Not only may ultrasound demonstrate the presence of a tumor mass at various sites in the abdomen, but it may also be useful in measuring the size of the mass. The rate of tumor growth or regression was followed by ultrasound in 28 patients with ovarian carcinoma undergoing chemotherapy. The ability of ultrasound to make precise measurements of tumor size is discussed, and the value of these measurements is explored. This quantification may be valuable in the assessment of therapeutic response in pelvic cancer, and the technique may be applicable to other intra-abdominal mass lesions.

Adenocarcinoma↗
PubMedDate not supplied

Cranial CT findings in sclerosteosis.

Sclerosteosis or Van Buchem's disease is a rare genetic craniotubular hyperostosis that becomes evident in early childhood and is associated with progressive involvement of the skull. The pathologic changes in the cranium noted on CT are described in three cases. Although the disease is incurable, CT is useful to display the morbid anatomy of the cranium before palliative surgery.

Adult↗