Electromagnetic flow measurement using a magnetic resonance imaging static field

Rationale and Objectives.: Electromagnetic flowmeters have been used for many years as a standard method to determine blood flow in animal models. The use of a modified probe to measure electromagnetic induction in response to an external, large direct current (DC) field magnetic resonance (MR) imaging system was investigated. Methods.: Extracted sheep iliac vessels were inserted into a pumped saline circuit with a modified probe and placed into a 2.0-T MR research imaging system. Voltage readings were collected at various flow rates ranging from 100 to 400 ml/min. Actual flows were measured with a graduated cylinder. Results.: A correlation of .937 (p < .001) was observed between the measured voltage changes and the actual flows. Baseline drift was also linear and within specified limits. Conclusion.: The results indicate that electromagnetic induction in a conductive fluid can be accurately measured using electrodes and an MR imaging system and that this technique provides possible opportunities for in situ flow measurements in humans.