ABSTRACT
A polyacrylamide gel (PAG) containing bovine serum albumin (BSA) is introduced as a new tissue-mimicking phantom for the purpose of visualizing three-dimensional coagulation temperature distribution during radiofrequency ablation (RFA). The coagulation temperature of the phantom can be changed at the same range of biological tissue (50-60 degrees C) by adjusting the pH from 4.3 to 4.7. The phantom is transparent except in thermal coagulation regions which are ivory white. The physical properties of the phantom, such as density, electrical conductivity and specific heat capacity, are very favorable, similar to those of soft tissues. We illustrate the usefulness of the phantom in visualizing RFA lesions. This phantom has magnetic resonance properties which change drastically upon thermal coagulation, enabling its use for the characterization of RFA device, quality assurance, treatment planning and treatment verification. The PAG containing BSA, whose pH was adjusted from 4.3 to 4.7, is an attractive tissue-mimicking phantom suitable for RFA investigations.
Subject(s)
Acrylic Resins , Catheter Ablation/methods , Phantoms, Imaging , Serum Albumin, Bovine , Catheter Ablation/instrumentation , Electric Conductivity , Hydrogen-Ion Concentration , Spectrophotometry , TemperatureABSTRACT
Objective To preliminarily evaluate the value of color power doppler ultrasonography in the diagnosis of sacroiliitis in ankylosing spondylitis(AS). Methods Fifty-seven sacroiliac joints in 31 patients with active AS and 40 sacroiliac joints in 20 volunteers were detected by color power doppler ultrasonography.The color flow signs inside the sacroiliac joints were observed,and the resistance index(RI) was measured. Results In active AS,color flow signs were seen in 55 joints,and the mean RI value was 0.53?0.08 in 45 joints,while the other 10 color flow signs represented reversed phase in diastolic phase on pulse doppler ultrasonography.In the volunteers,color flow signs were seen in 16 joints,and the mean RI value was 0.97?0.01 in 6 joints,while the other 10 color flow signs represented reversed phase in diastolic phase on pulse doppler ultrasonography. Conclusion The abnormal flow signs at the sacroiliac joints can be detected by color power doppler ultrasonography.Low RI values provide diagnosis evidence for active AS.
