Figure 2. Comparision of activation maps with and without susceptibility artifacts from SPM2. (a) true activation map. (b) activation map detected from phantoms without susceptibility artifacts. (c) activation map detected from phantoms with susceptiblity artifacts. More false activations are obsevered in (c), and the detected activation regions are spatially shifted relative to the true map (a...

Methods The new method has been validated in digital phantoms with actual echo times and noise levels taken from 5 patients. To achieve numerical stability at low T2* values, a novel hybrid curve fitting method was developed. For low values the residuals were weighted with the signal intensity and for high values standard exponential fitting was used. The transition between high and low regions...

The Radiological Physics Center (RPC) developed two heterogeneous anthropomorphic quality assurance phantoms for use in verifying the accuracy of radiation delivery: one for intensity-modulated radiation therapy (IMRT) to the pelvis and the other for stereotactic body radiation therapy (SBRT) to the thorax. The purpose of this study was to describe the design and development of these two phanto...

As an extension of previous work on computer-generated phantoms, more accurate, realistic phantoms are generated by integrating image distortion and signal loss caused by susceptibility variations. With the addition of real motions and activations determined from actual functional MRI studies, these phantoms can be used by the fMRI community to assess with higher fidelity pre-processing algorit...

EPI with Keyhole (EPIK) is a hybrid imaging technique used to improve the performance of EPI in dynamic MRI applications. The method had been previously validated at 1.5 T with both phantom and in vivo images; EPIK was able to provide a higher temporal resolution and less image distortions than single-shot EPI. The data presented here demonstrate that the performance of EPIK can be further impr...