Development of Enabling Technologies for Clinical Ultrahigh Field Body MRI

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The advent of clinically approved imaging at 7 Tesla (7T) has been met with high expectations. The potential benefits of increased signal-to-noise ratio (SNR), new contrasts and unprecedented resolution promise to extend what once was a tool for biomedical research into an imaging device defining state of the art patient care. The benefit of obtaining FDA approval is that it creates the opportunity for clinicians to investigate its true potential and to discover the applications where it uniquely impacts patient care. The current FDA approval however is only for head and knee applications, and even then, the MRI scanner is limited to using only a fraction of its installed functionality. Parallel transmit (pTx), a functionality that can tackle some of the biggest challenges facing ultrahigh field (UHF) MRI, has not been sufficiently developed, integrated and validated to safely use in the clinical setting. These challenges such as non-uniform transmit fields and issues with local heating scale with the size of the object being imaged. While imaging the head and knee can manage without this functionality, pTx it is an absolute necessity for applications in the human torso. While 7T has shown great potential at imaging targets in the torso in the research setting, there is the critical question of how to expand upon these promising results. We believe that several enabling technologies need to be further developed and integrated prior to obtaining FDA approval. These developments are addressed in three technical aims. The first is the development and optimization of radiofrequency (RF) coils to efficiently transmit RF energy into and receive signals from the body in order to realize the promised gains in SNR compared to lower field strengths. The second is the construction of a virtual database of human body models and strategies for overcoming the current limitations of assuming overly restrictive safety factors when attempting to use the pTx system. The third involves integrating pTx functionality into an extended multi-parametric prostate imaging protocol and motion compensation strategies through sequence tailored pTx solutions and optimization. A final translational aim will use the prostate as a testbed to explore the RF coils and pTx enabled sequences in a patient study comparing cancer detection and imaging metrics with the same patients imaged at 3T. Upon successful completion of these developmental and translational aims, we will have overcome the barriers to enabling clinical torso imaging at UHF and verified its effective use in a clinical setting. The outcomes of this project will be critical component in expanding the FDA approved indications for 7T. Once in the hands of clinicians, establishing the unique impact of UHF imaging on patient outcomes will greatly benefit from being able to use 7T as a front-line scanning modality.