Development of an MR-compatible, rotation-insensitive, annular pressure sensor

There is a growing interest in performing intravascular interventions guide d by MR imaging-a technique which offers the possibility of flow measuremen ts during the intervention. For a reliable assessment of the haemodynamic s ignificance of a stenosis, the flow and the pressure decay within the steno sis should both be measured. We have developed an optical, MR-compatible, p ressure sensor (Annupres) that uses a novel annular element. Existing optic al pressure sensors measure pressures unilaterally thus giving rise to arte facts because of the dependence of the measurement on the angular orientati on of the aperture. The annular element, however, measures blood pressure o n all sides, and we show that by using circularly polarized light this pres sure measurement is intrinsically insensitive to rotation of the sensor aro und its long axis. The Annupres sensor has been tested in an experimental s et-up, and was able to measure pressures from 50 mmHg to 180 mmHg reliably with an accuracy of 1.5%.