Biomedical subjects

C B Caldwell

Publications and source records attributed to C B Caldwell.

At least 19 recordsLinked to original sources

PubMed1992

Evaluation of mammographic image quality: pilot study comparing five methods.

A radiograph is considered of high quality when it allows a radiologist to identify abnormalities with high sensitivity and specificity. Although many methods for assessing image quality have been devised, it is not clear which is most meaningful or how well these methods correlate with one another. A pilot study was undertaken to compare five methods of evaluating mammographic image quality. Each of the methods was used to form separate rankings of 11 mammographic system configurations. In two of the methods, observers (three radiologists and three physicists) subjectively ranked the "image quality" of radiographs of phantoms obtained with each configuration. The third method ranked the systems according to contrast as measured densitometrically with an aluminum step wedge, and the fourth, in terms of lowest to highest mean glandular radiation doses to the breast. In the final method, observers based their rankings on mammograms of patients. The intra- and interobserver variabilities of each ranking method were assessed, as well as the correlations between methods, by using standard nonparametric statistical tests. Intraobserver consistency was high with any of the image quality ranking methods; however, image quality rankings based on either of the two phantoms provided better agreement among observers than did rankings based on images of patients. Surprisingly, no significant degree of correlation was found between any two image quality evaluation methods. Our work may have two implications for the American College of Radiology Mammography Accreditation Program: (1) small variations in phantom scores do not necessarily correlate with subjective variation in image quality in radiographs of patients, and (2) when small numbers of radiographs are used, the assessment of the quality of mammograms of patients may vary considerably among radiologists.

Accreditation↗

PubMed1992

Schizophrenia--a high-risk factor for suicide: clues to risk reduction.

Suicide is the chief cause of premature death among schizophrenic persons. The lifetime incidence of suicide for patients with schizophrenia is 10% to 13% compared to a general population estimate of about 1%, and is quite close to that observed among those with major affective disorder. The magnitude of increased risk for suicide among schizophrenics peaks before middle age and declines thereafter, although schizophrenic persons tend to be at increased risk throughout the life span. Among psychiatric patients, schizophrenics are overrepresented among suicides, and often schizophrenics constitute the majority of inpatient suicides. It is important in evaluating suicide risk among schizophrenic persons to assess depression and suicidal ideation especially during index admission and during acute phases of the illness. It is noteworthy that schizophrenic persons often commit suicide as the overall level of psychopathology decreases during a nonpsychotic phase. Research has yielded salient risk factors for suicide in schizophrenic persons and "types" of especially vulnerable patients, even though statistical prediction of individual suicides has not proven effective.

Adolescent↗

PubMed1991

Unusual malignant neoplasms of the esophagus. Oat cell carcinoma, melanoma, and sarcoma.

Primary noncarcinomatous malignant neoplasms of the esophagus are uncommon and data concerning treatment and results are sparse. To evaluate the results of therapy in this group, we reviewed the records of 32 patients with primary esophageal malignant tumors of unusual histologic type. Thirteen patients (41%) had sarcoma, eight (25%) melanoma, and 11 (34%) had oat cell carcinoma. Dysphagia was present in 78% (25/32) of the patients for a median of 13 weeks before diagnosis. Location of the esophageal primary tumor was upper third in four patients (12%), middle third in 12 (38%), and lower third in 16 (50%). Treatment consisted of esophagectomy in 10 of 13 patients with sarcoma (77%), seven of eight with melanoma (88%), and three of 11 with oat cell carcinoma (27%). Patients not undergoing resection received chemotherapy or radiation therapy, or both. The 3- and 5-year survival rates were 46% and 23% for sarcoma (median 20 months), 13% and 0% for melanoma (median 5 months), and 0% and 0% for oat cell carcinoma (median 5 months), respectively. Distant disease was the initial form of recurrence in 73% (11/15) of patients undergoing curative therapy. Surgical resection appears indicated for localized primary esophageal sarcoma. Optimum treatment of primary esophageal melanoma is less clear, but surgical resection may be of benefit in selected patients. Esophageal oat cell carcinoma is a systemic disease necessitating systemic therapy with local therapy reserved for palliation of dysphagia.

Adult↗

PubMed1990

Characterisation of mammographic parenchymal pattern by fractal dimension.

A consistent, quantitative, observer-independent method of characterising mammographic parenchymal pattern is described. The method is based on the calculation of the 'fractal dimension' of digitised mammograms. The degree of correlation between the parenchymal pattern classifications by a fractal-based system and those of radiologists is assessed. For a set of 70 mammograms, average weighted proportion agreement among three radiologists in calling Wolfe grades was 85%, while agreement between the radiologists and our fractal classifier was 84%. The method developed may prove to be useful in establishing an index of risk for breast cancer and, ultimately, in determining intervals between examinations for individuals in a mammographic screening programme.

Breast Neoplasms↗

PubMed1990

Schizophrenics kill themselves too: a review of risk factors for suicide.

Suicide rates among schizophrenic individuals are disturbingly high. At present, suicide is the number one cause of premature death among schizophrenics, with 10 to 13 percent killing themselves. Recent studies place the risk of suicide for persons with schizophrenia at a level comparable to that for persons with affective disorder. Depression, especially the symptom of self-reported or perceived hopelessness, is an important comorbidity factor in assessing this risk. Young white schizophrenic men with high levels of premorbid functioning and high expectations are at particularly high risk. Schizophrenic women, unlike women in the general population, behave more like men when it comes to choosing suicide. This article reviews recent studies reporting suicide rates and risk factors for suicide among schizophrenic patients. Current issues concerning the prediction, prevention, and treatment of suicidality among persons with schizophrenia are also discussed.

Cause of Death↗

PubMed1988

The role of parotidectomy in the treatment of cutaneous head and neck melanoma.

Sixty-five patients with melanoma underwent parotidectomy as part of the initial treatment. Clinical evaluation of the parotid nodal status was inaccurate. Patients with parotid nodal metastases had a significantly decreased survival at 5 years, 22 percent compared with 67 percent in the patients with uninvolved nodes. Distant metastasis was the first indication of treatment failure in most of the patients with parotid involvement.

Adolescent↗

PubMed1987

Changes in visceral blood flow with elevated intraabdominal pressure.

Elevated intraabdominal pressure (IAP) occurs with intraabdominal bleeding, with tense ascites, or after application of military anti-shock trousers to trauma patients. While changes in renal perfusion with elevated IAP have been documented, there are no data available on blood flow to other viscera. Under pentobarbital anesthesia an inflatable bag was placed intraabdominally to create graded increases in IAP in 9 adult mongrel dogs (20 kg). Hemodynamic parameters and organ blood flow (OBF) using radioactive microspheres were measured at baseline and after increasing the IAP to 20 and 40 mm Hg. The organ blood flow index (OBFI = OBF/cardiac output) was determined for each organ (stomach, duodenum, jejunum, ileum, colon, pancreas, liver, spleen, kidney, and adrenal gland). Elevated IAP caused a decrease in OBF for all organs measured except the adrenal glands where the OBF was increased. The OBFI was decreased significantly for all intraabdominal viscera except the renal cortex and the adrenal gland. These changes in OBF are more marked than can be accounted for by changes in cardiac output alone, suggesting that local control mechanisms may be responsible for changes in OBF. Our data raise the possibility that elevation in IAP may result in visceral ischemia and organ dysfunction.

Abdomen↗

PubMed1986

Anthropomorphic radiologic phantoms.

A technique is being developed for the design and fabrication of anthropomorphic phantoms for diagnostic x-ray imaging. Anatomic information extracted from actual patient radiographs is incorporated into the phantoms using computer image processing and computer-assisted machining methods. In this paper, the technique is described as applied to a breast phantom, and preliminary images that closely mimic human anatomy on radiographs are shown.

Automation↗

PubMed1985

Modification of lidocaine protein binding with CO2.

Using new, specially designed ultrafiltration devices and an enzyme immunoassay technique, the authors determined the effect of carbon dioxide tension on the fractional binding of lidocaine to human plasma proteins. Identical samples of serum at therapeutic (2.2 micrograms X ml-1) and toxic (6.8 micrograms X ml-1) lidocaine concentrations were tonometered at 37 degrees C to CO2 tensions between 0.13 and 10.7 kPa (1.0 to 80.5 mmHg). The fraction of unbound lidocaine increased linearly with increasing pCO2 (r = 0.93, p less than 0.001). These changes help to explain the increased central nervous system toxicity of lidocaine associated with hypercarbia.

Blood Proteins↗

PubMed1985

Induction dose-response curves for midazolam and ketamine in premedicated ASA class III and IV patients.

Using probit analysis, dose-response curves for induction of anesthesia with midazolam or ketamine were constructed in ASA class III and IV patients premedicated with morphine, 0.1 mg/kg, and glycopyrrolate, 4 micrograms/kg. For ketamine, ED50 values for abolition of the response to verbal commands, eyelash stimulation, and painful stimulation were 0.9, 1.3, and 1.3 mg/kg, respectively; corresponding ED95 values were 1.6, 2.3, and 4.3 mg/kg, which are within the range of clinically recommended doses. For midazolam, ED50 values for verbal commands, eyelash stimulation, and painful stimulation were 0.19, 0.24, and 0.36 mg/kg, significantly greater than those previously reported for unpremedicated ASA class I and II patients. The corresponding ED95 values, 0.35, 0.43, and 1.04 mg/kg exceed previously reported values and are appreciably greater than the doses used in most previous studies of midazolam induction. Midazolam decreased systolic blood pressure slightly but significantly (from 138 +/- 4 to 128 +/- 4 mm Hg, mean +/- SEM, P less than 0.005), while diastolic blood pressure and heart rate remained unchanged. In contrast, ketamine increased systolic blood pressure (from 141 +/- 4 to 164 +/- 5 mm Hg, P less than 0.005), diastolic blood pressure (from 71 +/- 3 to 88 +/- 4 mm Hg, P less than 0.005), and heart rate (from 84 +/- 2 to 102 +/- 4 beats/min, P less than 0.005). On the basis of these data, we conclude that in ASA class III and IV patients, midazolam induction allows for hemodynamic stability and avoids the significant tachycardia and hypertension associated with equipotent doses of ketamine.

Anesthesia, Inhalation↗

PubMed1978

Central control insufficiency. III. Disturbed motor control and sensation: a treatment approach emphasizing upper extremity orthoses.

In the discussion of the problems, the selection of patients, and some of the approaches to treatment, three major areas need emphasis. 1. Guidelines are necessary to select patients who require and can respond to treatment. The patients who will benefit the most must be identified and provided with structured therapy programs. 2. Effective bracing of the severely spastic wrist and hand may not be possible. The orthoses described are used to prevent deformity and relieve pain. 3. All motor control available to a patient must be incorporated immediately into the patient's daily activities.

Activities of Daily Living↗

PubMed1977