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Biomedical subjects

W H McCartney

Publications and source records attributed to W H McCartney.

At least 19 recordsLinked to original sources
PubMed1992

Radionuclide genital imaging.

Despite the emergence of newer cross-sectional imaging approaches, radionuclide techniques have maintained a significant role in genital imaging. While ultrasound is clearly superior for evaluation of scrotal anatomy, radionuclide scrotal imaging remains the most effective method for differentiating between testicular torsion and epididymitis. Labeled red blood cells have been used for varicocele detection in infertile men. Since radionuclide techniques can demonstrate the physiologic status of organs, they play a useful role in evaluating men with impotence (penile scan) and infertile women whose tubal patency is in question (radionuclide hysterosalpingogram).

Adolescent↗
PubMed1991

Comparison of the digital rectal examination, endorectal ultrasound, and body coil magnetic resonance imaging in the staging of adenocarcinoma of the prostate.

A series of 25 patients with biopsy proven adenocarcinoma of the prostate underwent preoperative staging evaluation with a digital rectal examination, endorectal ultrasound, and body coil magnetic resonance imaging (MRI) before their radical retropubic prostatectomy. The sensitivity and specificity of the digital rectal examination for the detection of extracapsular disease were 17 and 100%, respectively. The sensitivity and specificity of endorectal ultrasound for the detection of extracapsular disease were 35 and 89%, respectively. The sensitivity and specificity of body coil MRI for the detection of extracapsular disease by adenocarcinoma of the prostate were 47 and 63%, respectively. Microscopic disease of the capsule and seminal vesicles was the principle reason for understaging by both imaging modalities. This small series suggests that both imaging modalities are marginally more sensitive, albeit less specific, for extracapsular disease of the prostate than the digital rectal examination, with ultrasound having a slight edge in specificity and MRI having a slight edge in sensitivity.

Adenocarcinoma↗
PubMed1990

MRI of Askin's tumor. Case report at 1.5 T.

This represents the first case of an Askin's tumor demonstrated on MRI. It showed a large pleural-based mass which trapped pleural fluid in large pseudotumors. The disease was unilateral and involved the mediastinum as well. Magnetic resonance imaging was helpful in demonstrating extrathoracic disease in the area of the right brachial plexus.

Adult↗
PubMed1989

Correction of nonuniform attenuation in cardiac SPECT imaging.

Correction for photon attenuation in cardiac SPECT imaging using a measured attenuation distribution with an iterative expectation maximization (EM) algorithm and an iterative Chang algorithm were compared with the conventional filtered backprojection and an iterative EM algorithm without attenuation correction. The attenuation distribution was determined from a transmission computed tomography study that was obtained using an external collimated sheet source. The attenuation of the emitting photons was modeled in the EM algorithm by an attenuated projector-backprojector that used the estimated attenuation distribution to calculate attenuation factors for each pixel along each projection and backprojection ray. Results from a heart-lung phantom study and a 201Tl patient study demonstrated that the iterative EM algorithm with attenuation correction provided improved image quality in terms of reduced streak artifacts and noise, and more accurate quantitative information in terms of improved radioactivity distribution uniformity where uniformity existed, and better anatomic object definition.

Algorithms↗
PubMed1988

Anterior dynamic imaging of the liver and spleen.

Anterior dynamic imaging of the abdomen was performed in 870 patients using a large field-of-view (LFOV) gamma camera. Sequential images were obtained immediately after the injection of Tc-99m sulfur colloid (Tc-99m SC) in an antecubital vein for liver-spleen imaging and was followed by standard planar images. This provided additional information in 172 cases (20%), including such findings as determination of the lesion's vascularity in 76 (9%), visualization of abnormal portal blood flow in 53 (6%), and detection of abnormalities in the aorta, inferior vena cava, iliac vessels, or kidneys in 43 (5%) of these patients. This procedure is recommended in all patients undergoing liver-spleen imaging.

Adult↗
PubMed1988

Determination of the optimum filter function for SPECT imaging.

An observer study was performed in order to evaluate several filters used in SPECT imaging. The filters were applied to the simulated projection data of a uniform activity density cylinder which contained a cold, spherical lesion, 2 cm in diameter. The data incorporated the effects of the detector and scatter response functions, photon attenuation, and noise. Reconstructed transaxial images were used in 2AFC and ROC observer studies testing lesion detectability. In the 2AFC experiment, the Hanning filter scored lowest and did not show a optimum cutoff frequency. The Butterworth filter performed better and showed a well-defined optimum cutoff frequency at 0.15 cycles/pixel. The Metz filter performed as well as the optimum Butterworth but did not show an optimum power factor. In the ROC study, a high power Metz filter demonstrated an ROC curve of lower Az index and different shape from a lower power Metz filter and the optimum Butterworth filter.

Filtration↗
PubMed1987

Treatment of calcinosis universalis with low-dose warfarin.

Patients with calcinosis universalis secondary to dermatomyositis or systemic sclerosis have increased levels of the calcium-binding amino acid, gamma-carboxyglutamic acid. The enzyme that effects gamma carboxylation of glutamic acid is warfarin-sensitive. Four patients with calcinosis universalis were treated with 1 mg per day of warfarin for 18 months in a non-blind initial study. Two patients had both decreased gamma-carboxyglutamic acid urinary concentration and decreased extra-skeletal uptake on technetium 99m-diphosphonate whole-body nuclear scanning. In a subsequent double-blind placebo study, two thirds of the patients receiving 1 mg per day of warfarin had decreases in extra-skeletal nuclear tracer uptake after 18 months, compared with none of the four patients receiving placebo. No patient had a change in clinical assessment, bleeding complication, or baseline normal prothrombin time. This low-dose warfarin regimen appears to have no demonstrable adverse effects, and these results suggest a beneficial effect on the progression of calcinosis in these rheumatic diseases.

Bone and Bones↗
PubMed1987

Ozone exposure increases respiratory epithelial permeability in humans.

Ozone is a respiratory irritant that has been shown to cause an increase in the permeability of the respiratory epithelium in animals. We used inhaled aerosolized 99mTc-labeled diethylene triamine pentacetic acid (99mTc-DTPA) to investigate whether human respiratory epithelial permeability is similarly affected by exposure to ozone. In a randomized, crossover double-blinded study, 8 healthy, nonsmoking young men were exposed for 2 h to purified air and 0.4 ppm ozone while performing intermittent high intensity treadmill exercise (minute ventilation = 66.8 L/min). SRaw and FVC were measured before and at the end of exposures. Seventy-five minutes after the exposures, the pulmonary clearance of 99mTc-DTPA was measured by sequential posterior lung imaging with a computer-assisted gamma camera. Ozone exposure caused respiratory symptoms in all 8 subjects and was associated with a 14 +/- 2.8% (mean +/- SEM) decrement in FVC (p less than 0.001) and a 71 +/- 22% increase in SRaw (p = 0.04). Compared with the air exposure day, 7 of the 8 subjects showed increased 99mTc-DTPA clearance after the ozone exposure, with the mean value increasing from 0.59 +/- 0.08 to 1.75 +/- 0.43%/min (p = 0.03). These data show that ozone exposure sufficient to produce decrements in the pulmonary function of human subjects also causes an increase in 99mTc-DTPA clearance.

Adult↗
PubMed1986

Design and clinical utility of a fan beam collimator for SPECT imaging of the head.

A long bore fan beam collimator for imaging the head was designed and constructed for a SPECT system with a rotating scintillation camera. In order to avoid the patient's shoulder during rotation of the camera with a thick camera housing, the long bore design is necessary to allow the collimator to get close to the patient's head for improved spatial resolution. Operating at the minimum radius of rotation, the prototype fan beam collimator provides about the same spatial resolution as the high resolution collimator, while the geometric efficiency is equal to approximately 85% of that of the general purpose and approximately 55% higher than the high resolution collimator. Images from a phantom study demonstrate good image quality and are void of artifacts. Comparative clinical studies on temporomandibular joints (TMJ) between the LEGP and fan beam collimators also confirm the superior image quality obtained with the fan beam collimator.

Equipment Design↗
PubMed1986

Age-related loss of bone mineral density in non-athletic and athletic women.

Single and dual photon absorptiometry were performed at the mid-radius, distal radius and lumbar spine in 1105 non-athletic and 124 athletic Caucasian women aged 18-98 years. An age-related loss of bone mineral density in mg/cm2 (BMD) occurred at the three skeletal sites. It was first demonstrated that a single break in the regression line (BMD versus Age) best fit the data. The break represented the approximate age at which an increase in the rate of bone density loss occurred. This break is termed the 'cutpoint'. The approximate (average) age at which the cutpoint occurred was determined by segmented regression analysis with bone density as the dependent variable. The age range studied was between 45 and 55 years. At all three bone sites, the cutpoints in non-athletic women occurred between 47 and 52 years of age, corresponding roughly to the time of menopause. Following this cutpoint the rate of bone loss increased at all three locations in non-athletic women. In athletic women no cutpoint in BMD values could be demonstrated for this age range for the two radial sites. The number of lumbar spine measurements in this group was too small for analysis. The absence of a significant change in rate of bone loss in athletes could have been due to the relatively small number of subjects. It could also suggest that regular sustained exercise programs may delay or minimize the increased rate of loss of BMD which occurs in non-athletic women in the perimenopausal period.

Adolescent↗
PubMed1985

CSF rhinorrhea: detection and localization using overpressure cisternography with Tc-99m-DTPA.

We performed 32 overpressure radionuclide cisternography (ORNC) studies to examine 26 patients who were clinically suspected of having cerebrospinal fluid (CSF) fistula with rhinorrhea. Fifteen (47%) of these cisternography studies were positive, and the site of the leak was identified. No leak could be demonstrated in the other 17. Of 23 examinations performed in patients who had clinically documented CSF rhinorrhea, 15 (65%) were scintigraphically positive. The rapid cephalad transit of the radionuclide bolus allowed completion of the study within 30 to 45 minutes. Seven examinations were also performed with overpressure metrizamide CT cisternography (OMCTC), and five demonstrated concordant results with the radionuclide study. Patient discomfort and side effects were minimal. We conclude that radionuclide infusion cisternography is a safe, rapid, and accurate method of investigating a suspected or proven CSF rhinorrhea and that it is complementary to metrizamide cisternography.

Adult↗
PubMed1979

Computerized tomography applied to gynecologic oncology.

Forty patients on the gynecologic oncology service at the University of North Carolina were evaluated with CT scans. Accuracy and clinical benefit of these scans were compared to those of manual clinical examinations. The CT scans were generally superior and had fewer (9) verified errors in the regions of the pelvic wall and para-aortic area than did the manual examinations (17). Both the CT and bimanual examinations had the same number of verified errors (3) in the central pelvic region. The authors found the CT scans to be beneficial in evaluation of pelvic wall and para-aortic regions for treatment planning of either primary or recurrent cancer.

Diagnosis, Differential↗
PubMed1979

Multiple imaging modalities for the study of pancreatic disease.

Gray scale ultrasonography (US) and computed tomography (CT) have enhanced the role of various imaging modalities in the evaluation of patients with suspected pancreatic disease. When these anatomical studies are normal or equivocal, a functional, radionuclide pancreas scan may be useful. Pancreatic imaging can be achieved using ultrasound, transmission CT, single photon radionuclide imaging, and positron emission CT. A diagnostic imaging decision chart for the evaluation of patients with possible pancreatic disease is useful in choosing the correct imaging modality in a specific situation. Such a chart and its theoretic basis are described in this review. The need to optimize the pancreatic work-up with respect to cost-benefit decisions and diagnostic accuracy, sensitivity, and specificity are of particular concern to the physician. Of all the potential areas for disease, the pancreas has been and remains a particularly difficult diagnostic problem.

Humans↗
PubMed1979

Brain scan abnormalities in intracerebral sarcoidosis.

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.

Adult↗