Figure 3: Angio-catheters were placed into the synovium of the knees (A, arrow), such that subdermal polarographic probes attached to an OxyLite/ OxyFlow system (Oxford Optronix Ltd., London, England) could make intraarticular readings of blood perfusion (BPU), oxygen partial pressure (pO2), and temperature of the tissue in real time according to local increase and decrease of temperature. The functional scans were acquired while the temperature of one of the knees was increased, and again when it was decreased using a 3 inch receive-only surface coil (B, arrow). A heating/ cooling pad placed around the knee (A, arrowheads) and connected to a water circulator (C) was used to maintain the temperature above 40°C during the course of scanning, while attempting to remain not much higher than 42°C, and below 32°C, while attempting to remain not much lower than 30°C. The temperature of the joint was set using a temperature selector (C, circle) and was monitored using the readings of the OxyLite system.