Accuracy of area measurements made from MR images compared with computed tomography

The accuracy of area measurements made on magnetic resonance (MR) and CT images with clinical general purpose scanners was compared using automatic boundary detection. Both backprojection and two-dimensional Fourier transform reconstruction were used with several pulse sequences for the MR images. Several phantoms were scanned with different receiver coils and image matrices. Errors caused by grey level variation in MR images can be reduced using local edge detection. The estimated values varied with the sequence, reconstruction algorithm, and the area under investigation. Magnetic resonance area measurements should be interpreted with caution.