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Biomedical subjects

T R Miller

Publications and source records attributed to T R Miller.

At least 199 records · Page 11Linked to original sources
PubMed1984

Do the prognoses of papillary and follicular thyroid carcinomas differ?

Our 44 patients with follicular thyroid carcinoma had a survival rate similar to patients of the same age and sex with papillary carcinoma. By matching our patients by age and sex, this study appears to show that the biologic behavior of differentiated thyroid carcinomas is better correlated with the age and sex of the patients than with the pathologic classification of papillary carcinoma or follicular carcinoma; therefore, it is unnecessary to distinguish between patients with papillary carcinoma and follicular carcinoma from a prognostic standpoint. A classification considering all well-differentiated thyroid carcinomas as one disease with behavioral variability due to constitutional factors such as age and sex should be adopted.

Adenocarcinoma↗
PubMed1984

Atypical melanocytic hyperplasia of the vagina.

A case of extensive pigmentation of the vagina is reported. Microscopic sections showed a resemblance to atypical melanocytic hyperplasia, which has been described as a possible precursor of malignant melanoma of the skin including the acral lentiginous form.

Female↗
PubMed1984

Improved interpretation of gated cardiac images by use of digital filters.

The authors describe a digital filter that greatly enhances the quality of gated cardiac blood-pool images. Spatial filtering is accomplished with a minimum-mean-square-error (Wiener) filter incorporating measured camera blur and Poisson noise statistics. A low-pass temporal filter is then applied to each pixel, with the cutoff frequency determined from measurements of frequency spectra in 20 patients. This filter was evaluated in routine clinical use for nearly one year and found to significantly improve chamber definition, delineate wall motion abnormalities better, and reduce noise. To quantitatively assess the effect of the filter on image interpretation, four experienced observers evaluated wall motion in a series of mathematically simulated left ventricular images. ROC analysis revealed that accuracy in assessing wall motion was significantly greater with the filtered images.

Evaluation Studies as Topic↗
PubMed1984

The Japanese management theory jungle.

Many competing hypotheses have been advanced to account for the apparent effectiveness of Japanese management practices. The present review of some of the leading theories attempts to classify and clarify the state of knowledge of Japanese management. Although each theory may be correct as a partial explanation of Japan's success, no single conceptualization has captured the complexity of Japan's managerial achievement. Further development of integrated, internally consistent models is needed.

Group Processes↗
PubMed1984

Merkel cell carcinoma of the vulva.

The authors describe the clinical and histologic findings in a case of Merkel cell carcinoma of the vulva, which was associated with squamous cell carcinoma in situ and lichen sclerosus. Electron microscopy of the tumor revealed membrane-bound granules. At postmortem examination, metastases from this primary skin tumor were found in the pelvic lymph nodes, in paraortic lymph nodes, in the liver, and in vertebral bodies. The case is unusual because Merkel cell tumors are usually found on the face or the extremities and seldom metastasize widely.

Aged↗
PubMed1984

A versatile computer simulation of the left ventricle.

A versatile mathematical simulation of a beating left ventricle, as seen in a gated cardiac blood-pool study, is described. The basic model consists of a fifth-degree polynomial rotated about its long axis. Motion is mimicked by sinusoidally varying the lengths of the long and short axes. The quality of clinical images is simulated through addition of Poisson noise and camera blur, determined from the measured line-spread function for Tc-99m. To achieve added realism, the modeled ventricle can be inserted in place of the patient's actual ventricle in clinical images. The dimensions, activity, and ejection fraction can all be adjusted. In addition, regional wall-motion abnormalities can be generated in any of the walls. To illustrate applications of the model in testing and evaluating cardiac computer programs, the performances of two ejection-fraction programs are compared, and use of the model in evaluating digital filtering algorithms is discussed.

Computers↗
PubMed1983

Fine-needle aspiration of palpable breast masses. A program for staged implementation.

Fine-needle aspiration (FNA) can provide a morphologic diagnosis of palpable breast masses in an accurate, efficient, inexpensive, and safe manner. However, how one acquires the skill to perform the FNA and interpret the resulting smears, while protecting the patient from the risk of false-positive or false-negative results, is scarcely considered. We used a three-phase program to acquire experience with FNA while providing services for 205 patients over a 16-month period. We performed FNA sequentially in vitro, in vivo, and finally in vivo for clinical use. With available literature and this graduated implementation program, physicians totally inexperienced with FNA can achieve results similar to those of medical centers having experience with thousands of patients.

Biopsy, Needle↗
PubMed1983

Pulmonic regurgitation due to valvular tophi.

Documented cardiac tophi are rare and have not previously been reported to cause clinically manifest valvular disease. A 31-year-old male with complex cyanotic congenital heart disease (Taussig-Bing anomaly) and secondary tophaceous gouty arthritis is described. Terminally, he presented with clinical evidence of a brain abscess and a new semilunar regurgitant murmur. Two-dimensional echocardiography suggested vegetative lesions as the cause of the murmur. The patient was treated for infective endocarditis. At autopsy, the cause of the semilunar regurgitant murmur was shown to be sterile tophi located along the line of pulmonary valvular coaptation. Tophaceous deposits were also present in the mitral valve.

Adult↗
PubMed1983

Fast count-dependent digital filtering of nuclear medicine images: concise communication.

The formulation of an "optimal" filter for improving the quality of digitally recorded nuclear medicine images is reported in this paper. The method forms a Metz filter for each image based upon the total number of counts in the image, which in turn determines the average noise level. The parameters of the filter were optimized for a set of simulated images using the minimization of the mean-square error as the criterion. The speed of the image formation results from the use of an array processor. In a study of localization receiver operating characteristics (LROC) using the Alderson liver phantom, a significant improvement in tumor localization was found in images filtered with this technique, compared with the original digital images and those filtered by the nine-point binomial smoothing algorithm. The technique has been found useful for the filtering of static and dynamic studies as well as the two-dimensional pre-reconstruction filtering of images from single photon emission computerized tomography.

Computers↗
PubMed1983

Analysis of cardiac diastolic function: application in coronary artery disease.

Separation of systolic and diastolic parameters in gated cardiac blood-pool imaging (RVG) was achieved with the retention of two harmonics in the Fourier-series representation of the time-activity curve. Regional and global analysis of left-ventricular peak filling rate (PFR) and time to peak filling (TPF) was performed in 18 control subjects, 20 patients with coronary artery disease (CAD) but with normal RVG (normal regional wall motion and ejection fraction, and 16 CAD patients with abnormal RVG. In regional analysis of CAD patients, the standard deviation of the TPF histogram identified 13/20 (65%) of normal RVG patients and 12/16 (75%) of abnormal RVG patients as abnormal. In global analysis of CAD patients, PFR values identified 10/20 (50%) of normal RVG patients and 11/16 (69%) of abnormal RVG patients as abnormal. Thus, left-ventricular systolic and diastolic parameters can be separately measured with retention of higher-order harmonics in the Fourier transform, and regional inhomogeneity of diastolic filling can be detected in CAD patients with normal resting ejection fraction and wall motion.

Computers↗
PubMed1983

Rapid digital filtering.

Image filtering with the larger, and potentially most valuable, digital filters is very time-consuming, thus precluding use of these filters in routine clinical applications. A recently developed algorithm for spatial-domain filtering is described, and its speed is compared with those of conventional methods with and without an array processor. Using the new Chebyshev method, a 64 by 64 pixel image can be filtered on a standard 16-bit minicomputer with filters of size 3 by 3 to 23 by 23 in 1.4-9.2 sec. The conventional spatial-domain algorithm requires 3.8-71 sec. With an array processor, filtering is accomplished in 0.19-0.54 sec. Filtering in the frequency domain requires 34 sec without an array processor and 0.12 sec with one. Thus with this new Chebyshev algorithm, clinically practical digital filtering can be performed with large filters even without an array processor.

Computers↗
PubMed1982

Design and application of finite impulse response digital filters.

The finite impulse response (FIR) digital filter is a spatial domain filter with a frequency domain representation. The theory of the FIR filter is presented and techniques are described for designing FIR filters with known frequency response characteristics. Rational design principles are emphasized based on characterization of the imaging system using the modulation transfer function and physical properties of the imaged objects. Bandpass, Wiener, and low-pass filters were designed and applied to 201Tl myocardial images. The bandpass filter eliminates low-frequency image components that represent background activity and high-frequency components due to noise. The Wiener, or minimum mean square error filter 'sharpens' the image while also reducing noise. The Wiener filter illustrates the power of the FIR technique to design filters with any desired frequency response. The low-pass filter, while of relative limited use, is presented to compare it with a popular elementary 'smoothing' filter.

Filtration↗
PubMed1982

Digital filtering in nuclear medicine.

Digital filtering is a powerful mathematical technique in computer analysis of nuclear medicine studies. The basic concepts of object-domain and frequency-domain filtering are presented in simple, largely nonmathematical terms. Computational methods are described using both the Fourier transform and convolution techniques. The frequency response is described and used to represent the behavior of several classes of filters. These concepts are illustrated with examples drawn from a variety of important applications in nuclear medicine.

Computers↗
PubMed1981

Ventilation imaging with Kr-81m. A comparison with Xe-133.

Sixty-five patients with suspected pulmonary embolism were studied prospectively with both Kr-81m and Xe-133 ventilation imaging and Tc-99m MAA perfusion imaging. The krypton images, perfusion scintigrams and chest radiographs were read independently of the xenon images, perfusion scintigrams and chest radiographs by three observers. The studies of 53 patients were interpreted as normal or as indicative of a low or intermediate probability for pulmonary embolism with both gases. One study indicated intermediate probability with Xe-133 due to diffuse, severe xenon retention but low probability with Kr-81m because of close ventilation-perfusion correspondence. The studies of 9 patients indicated a high probability of embolism with both gases, while those of two additional patients (one with emboli at angiography) indicated a high probability only with Kr-81m. While essential agreement between Xe-133 and Kr-81m ventilation imaging was found in most patients, the significant difference in interpretation in 2 of 11 patients with probable pulmonary embolism suggests that a controlled, prospective trial with pulmonary angiography is warranted before Kr-81m is employed for routine clinical use.

Humans↗
PubMed1981

Positron tomographic imaging of the liver: 68 Ga iron hydroxide colloid.

A new radiopharmaceutical, 68Ga ion hydroxide colloid, for hepatic imaging by positron emission tomography was prepared from the eluate of a 68Ge-68Ga solvent extraction generator. In rats, 84% of the administered dose of colloid localized in the liver and 4.6% accumulated in the spleen. Initial imaging studies in normal dogs showed close correspondence of the findings by positron tomography and transmission computed tomography. Emission tomography with 68Ga-colloid was performed in 10 patients with hepatic metastases demonstrated by conventional 99mTc sulfur colloid scintigraphy. All focal defects noted on the conventional scintigrams were easily identified and generally were seen more clearly by positron tomography. In one patient, additional lesions not identified on the initial 99mTc sulfur colloid images were demonstrated. The positron tomographic images were compared with those obtained by transmission computed tomography in seven patients; the two studies showed comparable findings in five patients, whereas positron tomography more clearly showed multiple lesions in two. Our results suggest that positron emission tomography is a suitable technique for obtaining high contrast, cross-sectional images of large abdominal organs.

Animals↗
PubMed1981

Evaluation of computer display systems using digital test patterns.

Two digital test patterns are used to evaluate computer video display systems. One pattern consists of linear and logarithmic gray-scale wedges, blocks of constant brightness, and horizontal and vertical bar patterns. The other is a cross-hatch bar pattern. These patterns are used to assess display systems' gray scale, resolution, and spatial linearity. Microdensitometry measurements were performed to determine brightness uniformity, spatial resolution, and to relate optical density to exposure. These test patterns, used qualitatively, are useful in the routine adjustment and quality control of digital systems. The precise quantitative characterization of a display system is important in research applications involving image processing.

Computers↗