Biomedical subjects

C F Maier

Publications and source records attributed to C F Maier.

4 recordsLinked to original sources

PubMed1998

Practical design of a high-strength breast gradient coil.

A high-strength three-axis local gradient coil set was constructed for MRI of the breast. Gradient fields with good uniformity (<10% deviation from the desired gradient) over most of the volume required for breast imaging were generated with efficiencies of up to 3.3 mT/m/A. The coils will allow diffusion breast imaging in clinically acceptable examination times. The electrical design, water cooling system, and fabrication techniques are described. Preliminary tests of the coil included images of a grid phantom and diffusion measurements in a short-T2 agarose gel phantom.

Artifacts↗

PubMed1998

Invasive carcinomas and fibroadenomas of the breast: comparison of microvessel distributions--implications for imaging modalities.

PURPOSE: To compare spatial patterns of blood vessels between invasive breast carcinomas and fibroadenomas to improve the diagnostic specificity of noninvasive vascular magnetic resonance imaging and color Doppler ultrasound. MATERIALS AND METHODS: Nineteen invasive ductal carcinomas and 20 fibroadenomas from 39 patients were stained for factor VIII-related antigen. Vessels smaller than 40 microns were counted in x200 fields defined in peripheral and central areas of the tumor and in normal tissue adjacent to fibroadenomas. Significant differences in vessel density were determined with Student t tests and one-way analyses of variance. Distributions of vessels 40 microns or larger were qualitatively evaluated. RESULTS: There were 9-105 vessels (mean, 31.4 vessels) smaller than 40 microns per x200 peripheral and 4-57 vessels (mean, 20.1 vessels) smaller than 40 microns per x200 central carcinoma field. There was no significant difference in vessel density between the two groups. Peripheral microvessel density was significantly higher (P < .01) than central microvessel density in 15 (79%) of the 19 carcinomas and in three (16%) of 19 fibroadenomas. (A Student t test could not be performed in one case of fibroadenoma; size permitted only one countable field according to the authors' criteria.) The 18 cases with normal tissue had 21-229 vessels (mean, 80.5 vessels) per field; in 16 (89%) of the 18 cases, these vessel counts were significantly higher (P < .01) than those in the fibroadenoma cases. Vessels 40 microns or larger were found mainly in the periphery of carcinomas and were more uniformly distributed in fibroadenomas. CONCLUSION: Evaluation of the spatial distribution of vessels and the ability to resolve vessel sizes may add valuable information to the imaging-based diagnostic work-up of indeterminate solid breast lesions.

Adult↗

PubMed1997

Quantitative diffusion imaging in implanted human breast tumors.

Quantitative diffusion measurements were performed in tumors arising from inoculation of nude mice with two human breast cancer cell lines (MCF7 and T47D) to evaluate the specificity of this technique for characterizing solid tumors. ADC maps were compared to histology and correlated well with gross tumor morphology. Measured ADCs were highly specific for viable and necrotic tumor in the five T47D tumors included in this study (P < 0.02), while only two of the five MCF7 tumors studied developed distinguishable areas of necrosis. No statistically significant difference was observed in ADCs from viable tumor between the different cell lines (P > 0.05).

Animals↗

PubMed1995

A novel transverse gradient coil design for high-resolution MR imaging.

The authors describe a new gradient coil design for high resolution human, animal, specimen, or phantom imaging with high gradient efficiency and a large region of excellent gradient uniformity. Important features of our new design are the simple analytical description of the wire patterns that comprise the design, and ease of construction. Wires are spaced in a sinusoidal distribution around the circumference of the cylinder, and curved in an arcsin shape along the length of the cylinder. This coil produces a magnetic field pointing in a direction transverse to the axis of the coil with a gradient in the direction parallel to the axis of the coil. The same arcsin coil can be used to create a magnetic field pointing in a direction parallel to its axis with a gradient in a direction perpendicular to the coil axis. A prototype coil was constructed; field and inductance calculations were verified. Geometric variations on this coil design were modeled and their performance characteristics compared. This coil design is ideal for rapid implementation of a transverse gradient coil, since no specialized design software is required.

Algorithms↗