High Dynamic Range Processing for Magnetic Resonance Imaging

PURPOSE: To minimize feature loss in T(1)- and T(2)-weighted MRI by merging multiple MR images acquired at different T(R) and T(E) to generate an image with increased dynamic range. MATERIALS AND METHODS: High Dynamic Range (HDR) processing techniques from the field of photography were applied to a series of acquired MR images. Specifically, a method to parameterize the algorithm for MRI data was developed and tested. T(1)- and T(2)-weighted images of a number of contrast agent phantoms and a live mouse were acquired with varying T(R) and T(E) parameters. The images were computationally merged to produce HDR-MR images. All acquisitions were performed on a 7.05 T Bruker PharmaScan with a multi-echo spin echo pulse sequence. RESULTS: HDR-MRI delineated bright and dark features that were either saturated or indistinguishable from background in standard T(1)- and T(2)-weighted MRI. The increased dynamic range preserved intensity gradation over a larger range of T(1) and T(2) in phantoms and revealed more anatomical features in vivo. CONCLUSIONS: We have developed and tested a method to apply HDR processing to MR images. The increased dynamic range of HDR-MR images as compared to standard T(1)- and T(2)-weighted images minimizes feature loss caused by magnetization recovery or low SNR.