Biomedical subjects

D M Goldhaber

Publications and source records attributed to D M Goldhaber.

5 recordsLinked to original sources

PubMed2001

Ghost imaging in MRI.

Needle biopsies and other interventions done under MR Fluoroscopy sometimes do not show the target well, either because the rapid sequence does not have adequate contrast or because a contrast agent may have washed out of the target. In these cases, an image that shows the target can be saved and scaled to match the spatial parameters of the fluoroscopic sequence, and used as a virtual or ghost field upon which the fluoroscopic images are superimposed, thus providing a view of the target, useful for needle pre-localization and for monitoring its progress as it is inserted.

Biopsy, Needle↗

PubMed2000

Ghost imaging for targeting breast masses with MR imaging: a phantom study.

RATIONALE AND OBJECTIVES: The purpose of this study was to test the accuracy of ghost magnetic resonance (MR) imaging for guiding core biopsies of simulated breast masses in a tissue phantom. MATERIALS AND METHODS: A tissue MR phantom implanted with 20 grapes as targets was placed into an interventional breast MR coil. The locations of the centers of the targets were determined, recorded, and saved as ghost images. A nonmagnetic phantom needle was constructed to avoid imprecision secondary to magnetic field inhomogeneity and was used to determine the three-dimensional location of the needle tip in the center of each grape on the ghost image. Once the positions were determined, the true needle was placed and biopsy specimens were taken. The needle was inspected for the presence of pulp after each pass. Each grape was inspected to determine the location of the needle track in relation to the center of the grape. The duration of the procedure was recorded. RESULTS: All grapes were hit by the biopsy needle, as demonstrated either by pulp within the needle or by a needle track within the grape. Seventeen of the 20 grapes (85%) were hit centrally. Three were sampled eccentrically, up to 5-6 mm from the center. Each biopsy took approximately 1 hour. CONCLUSION: These results suggest that ghost imaging may be ideal for needle guidance in core biopsy or preoperative localization, as it extends the period of visibility after a bolus injection of contrast material. Additionally, using a phantom needle for localization appears to overcome imprecision due to magnetic field inhomogeneity of the needle.

Animals↗

PubMed1992

MR relaxometry imaging. Work in progress.

Acquisition of relaxation rate dispersion curves from magnetic resonance images was demonstrated on a clinical, whole-body imaging system. Study of the behavior of relaxation rates over a range of field strengths probes the structural environment of imaged hydrogen protons and reveals information about the composition of tissue. The authors determined relaxation rates in extremities and heads of healthy volunteers. The sensitivity of the measurement is sufficient to obtain a distinctive relaxation rate dispersion behavior for different tissues.

Adult↗

PubMed1986

Observations of neutral atomic carbon at 809 GHz.

We have detected the 809 GHz 3P2-3P1 fine-structure line of neutral atomic carbon in four dense molecular clouds: M17, W51, W3, and DR 21(OH). These observations complement the published observations of the 492 GHz 3P1-3P0 line and allow the excitation temperature of the 3P levels along with the line optical depths to be determined. The results indicate excitation temperatures Tx approximately 30-60 K and optical depths of tau 10 < or approximately 1. This implies that the approximately 10(18) cm-2 lower limit to the C I abundance derived from 492 GHz observations is probably the actual abundance, which gives C I/CO approximately 0.1 in dense molecular clouds.

Aircraft↗

PubMedDate not supplied

Separation of water and fat MR images in a single scan at .35 T using "sandwich" echoes.

A method was developed for separation of water and fat MR images in a single scan with correction of static field inhomogeneity. The imaging sequence uses a single radiofrequency (RF) echo that is "sandwiched" between two gradient echoes. The gradient echoes are used to determine the B(0) distribution and to produce out-of-phase images after phase correction using the field map. An algorithm was developed to unwrap the phase images for quantitating the B(0) inhomogeneity. To account for differences in geometric distortion between the RF echo image and the gradient echo images due to the reversal of the read gradients, methods were developed to correct the images before the calculation of the final water and fat images. The proposed technique was implemented at .35 T. Both phantom and human images were acquired using the method. It is shown that water- and fat-separated images can be obtained in a single scan using the "sandwich" echoes in the presence of a relatively large B(0) inhomogeneity.

Adipose Tissue↗