An apparatus for MR-guided breast lesion localization and core biopsy: design and preliminary results.

System design and initial results are presented from a new unilateral MR-guided breast lesion localization and core biopsy system. Over 150 imaging studies, an accuracy study on phantoms with 50 localization wire deployments and 33 core biopsy trials, and 19 clinical procedures are reported. The mean spatial accuracy from the lesion center for a 20-gauge (G) needle (N = 13) was within 1.2 +/- 1.4 mm (SD) and for a 14G biopsy (N = 4) 0.8 +/- 1.1 mm. For sampling using a 16G core through a 14G needle, the mean accuracy was 5.6 mm (N = 2). The needle guide geometry imposed a small, calculable targeting error. For phantom measurements using the 20G device, the mean geometry-induced error was 0.73 +/- 0.43 mm. However, this contribution was, on average, 42% of the mean measured 2.35 +/- 1.65 mm offset. The new device design provided an accurate and simple guidance method for localization or core biopsy of MR-visible breast lesions.

Functional MRI of the lumbar spine in erect position in a superconducting open-configuration MR system: preliminary results.

The purpose of this study was to determine the feasibility of obtaining, and findings in, functional MRI of the lumbar spine in an erect position and with flexion and extension. Thirty subjects (including 5 volunteers) were imaged in a sitting position and while performing flexion and extension. The alternations in posterior disk margin, size of neural foramina, and central canal were evaluated. In addition, routine supine imaging was accomplished in 15 of these subjects. The foraminal size and posterior disk margins did not change appreciably from supine to upright position. With extension, there was an increased disk bulge in 27% of disks (40% of those with desiccation). Central canal size (50%) and foraminal size (27%) decreased with extension, especially at levels with disk desiccation. Images obtained with our open-configuration MR unit were diagnostically adequate, although of inferior quality compared with those obtained with a conventional unit. Our preliminary results show the feasibility of obtaining diagnostic images of the erect lumbar spine with flexion and extension. The results are in agreement with those obtained with cadaveric studies. The utility of this method in diagnostic imaging of patients with low back pain remains to be determined.

An NMR phased array for human cardiac 31P spectroscopy.

A four-coil phased-array 31P NMR receiver was designed and tested for human cardiac applications, to determine whether the combination of relatively high signal-to-noise ratio (SNR) and large field of view produced in 1H imaging is also realized for in vivo 31P spectroscopy. Spectra were acquired in parallel from an array of four overlapping 6.5-cm surface coils using one- and two-dimensional phase-encoding pulse sequences and were optimally combined to yield composite spectroscopic images. The phased array was found to generate useful 31P spectra from a 2.5-fold wider lateral region around the anterior myocardium than a single receiver of the same size as the array elements, with no increase in imaging time. In addition, the sensitive depth was increased by up to 2 cm over that of a single coil. Spectra could be acquired in roughly 15 min from a region extending to the middle of the heart, with voxel sizes of 2 x 2 x 4 cm3. For the average heart voxel, the SNR of the combined spectrum was higher than that of the best spectrum from any one coil in the array by 30%, with some voxels showing an increase as high as 60%.