Electron spin resonance (ESR) probe for interventional MRI instrument localization

This article presents a miniaturized electron spin resonance (ESR) probe fo r deducing the position of a surgical instrument on an MR image, The ESR pr obe constructed was small enough to fit inside a 14-G biopsy needle sheath, and position information of the sheath could be acquired using a simple gr adient sequence. The position accuracy was estimated from needle trajectori es as inferred from the needle artifact, the actual physical trajectory. an d measured coordinates. The probe was able to track the tip of a biopsy nee dle quickly (10 samples/sec) and precisely with accuracy better than +/-2 m m, (C) 1999 Wiley-Liss, Inc.