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Biomedical subjects

Q Fang

Publications and source records attributed to Q Fang.

98 records · Page 6Linked to original sources
PubMedDate not supplied

Image accuracy improvements in microwave tomographic thermometry: phantom experience.

Evaluation of a laboratory-scale microwave imaging system for non-invasive temperature monitoring has previously been reported with good results in terms of both spatial and temperature resolution. However, a new formulation of the reconstruction algorithm in terms of the log-magnitude and phase of the electric fields has dramatically improved the ability of the system to track the temperature-dependent electrical conductivity distribution. This algorithmic enhancement was originally implemented as a way of improving overall imaging capability in cases of large, high contrast permittivity scatterers, but has also proved to be sensitive to subtle conductivity changes as required in thermal imaging. Additional refinements in the regularization procedure have strengthened the reliability and robustness of image convergence. Imaging experiments were performed for a single heated target consisting of a 5.1 cm diameter PVC tube located within 15 and 25 cm diameter monopole antenna arrays, respectively. The performance of both log-magnitude/phase and complex-valued reconstructions when subjected to four different regularization schemes has been compared based on this experimental data. The results demonstrate a significant accuracy improvement (to 0.2 degrees C as compared with 1.6 degrees C for the previously published approach) in tracking thermal changes in phantoms where electrical properties vary linearly with temperature over a range relevant to hyperthermia cancer therapy.

Algorithms↗
PubMedDate not supplied

Microwave thermal imaging: initial in vivo experience with a single heating zone.

The deployment of hyperthermia as a routine adjuvant to radiation or chemotherapy is limited largely by the inability to devise treatment plans which can be monitored through temperature distribution feedback during therapy. A non-invasive microwave tomographic thermal imaging system is currently being developed which has previously exhibited excellent correlation between the recovered electrical conductivity of a heated zone and its actual temperature change during phantom studies. To extend the validation of this approach in vivo, the imaging system has been re-configured for small animal experiments to operate within the bore of a CT scanner for anatomical and thermometry registration. A series of 5-7 day old pigs have been imaged during hyperthermia with a monopole antenna array submerged in a saline tank where a small plastic tube surgically inserted the length of the abdomen has been used to create a zone of heated saline at pre-selected temperatures. Tomographic microwave data over the frequency range of 300-1000 MHz of the pig abdomen in the plane perpendicular to the torso is collected at regular intervals after the tube saline temperatures have settled to the desired settings. Images are reconstructed over a range of operating frequencies. The tube location is clearly visible and the recovered saline conductivity varies linearly with the controlled temperature values. Difference images utilizing the baseline state prior to heating reinforces the linear relationship between temperature and imaged saline conductivity. Demonstration of in vivo temperature recovery and correlation with an independent monitoring device is an important milestone prior to clinical integration of this non-invasive imaging system with a thermal therapy device.

Abdomen↗
PubMedDate not supplied

Synovial T cell receptor heterogeneity in early arthritis.

Rheumatoid arthritis (RA) has been postulated to result from a synovial immune response to an unidentified antigen(s), which should be mirrored by the T cell response. Here we investigate the T cell receptor (TCR) repertoire in the synovial tissue of patients with arthritis of early to moderate duration. We developed a nested polymerase chain reaction (PCR) technique to examine the TCR repertoire of small biopsy specimens, and show that the method is highly sensitive. We apply this technique to synovial biopsies obtained from the knee joints of patients with early to moderate duration arthritis (average duration of arthritis 1 year, range 0. 02-2.75 years). We examined biopsies from 5 normal individuals, 32 RA patients, 7 patients with seronegative spondyloarthropathy (Sp), and 12 patients with undifferentiated arthritis (UA). TCR message was detectable in 4/5 normals, 15/32 RA, 5/7 Sp, and 8/11 UA biopsies, with sampling error likely accounting for most negative biopsies. The average numbers of TCR Vbetas detected per TCR-positive biopsy were 5.0 +/- 3.7 for normals, 12.7 +/- 8.4 for RA, 18.0 +/- 7.4 for Sp patients, and 14.4 +/- 10.2 for UA. Examination of TCR messages by single-stranded conformational polymorphism analysis showed similar proportions of dominant clones in the normals compared with the patients with inflammatory arthritis. Sequence analysis was performed on 33 dominant clones from 16 patients. Sequence alignment of the third hypervariable regions showed some evidence of disease-specific sequence clustering for Sp, while some RA sequences showed similarity to previously described motifs. These data indicate greater TCR heterogeneity in early Sp and UA compared with normal synovium. Disease-specific TCR sequences may occur in early RA and Sp.

Adult↗
PubMedDate not supplied

Cell transplantation as an experimental treatment for Duchenne muscular dystrophy.

The feasibility, safety, and efficacy of myoblast transfer therapy (MIT) were assessed in an experimental lower body treatment (LBT) involving 32 Duchenne muscular dystrophy (DMD) boys aged 6-14 yr, half of whom were nonambulatory. Through 48 injections, five billion (55.6 x 10(6)/mL) normal myoblasts were transferred into 22 major muscles in both lower limbs, in 10 min with the subject under general anesthesia. Ten subjects received myoblasts cultured from satellite cells derived from 1-g fresh muscle biopsies of normal males aged 9-21 yr. Donor myoblasts for the remaining 22 boys were subcultured from reserves frozen 1 mo-1.5 yr ago. Only four donors were known to have identical histocompatibility with their recipients. All subjects took oral doses of the immunosuppressant cyclosporine (Cy), beginning at 2 days before MTT and lasting for 6 mo after MTT to facilitate donor cell survival. There was no evidence of an adverse reaction to MTT or Cy as determined by serial laboratory evaluations including electrolytes, creatinine, and urea. Objective functional tests using the KinCom Robotic Dynamometer measured the maximum isometric contractile forces of the ankle plantar flexors (AF), knee flexors (KF), and knee extensors (KE) before MTT and at 3, 6, and 9 mo after MTT. The AF, being distal muscles and less degenerative than the KE and the KF, showed no decrease in mean contractile force 3 mo after MTT, and progressive increases in force at 6 and 9 mo after MTT. At 9 mo after MTT, 60% of the 60 AF examined showed a mean increase of 50% in force; 28% showed no change; and only 12% showed a mean decrease in force of 29% when compared to the function of the same muscles before MTT. The KF, being proximal muscles and more degenerative, showed no change in function at 9 mo after MTT. The KE, being proximal and anti-gravitational, were most degenerative before MTT. They showed no statistically significant change in force at 3 mo after MTT but showed decreases at 6 and 9 mo after MTT. At 9 mo after MTT, 23% of the 60 KE examined showed a mean increase of 65% in force; 22% showed no change; and 55% showed a mean decrease of 24% in force. When results of all muscle groups (AF, KF, KE) were pooled, there was no change in force at 3, 6, or 9 mo after MTT vs. before MTT according to the Wilcoxon signed rank test.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗