Contrast-enhanced, three-dimensional, whole-brain, black-blood imaging: application to small brain metastases

Contrast-enhanced three-dimensional T(1)-weighted imaging based on magnetization-prepared rapid-gradient recalled echo is widely used for detecting small brain metastases. However, since contrast materials remain in both blood and the tumor parenchyma and thus increase the signal intensity of both regions, it is often challenging to distinguish brain tumors from blood. In this work, we develop a T(1)-weighted, black-blood version of single-slab three-dimensional turbo/fast spin echo whole-brain imaging, in which the signal intensity of the brain tumor is selectively enhanced while that of blood is suppressed. For blood suppression, variable refocusing flip angles with flow-sensitizing gradients are employed. To avoid a signal loss resulting from the flow-sensitizing scheme, the first refocusing flip angle is forced to 180 degrees. Composite restore pulses at the end of refocusing pulse train are applied to achieve partial inversion recovery for the T(1)-weighted contrast. Simulations and in vivo volunteer and patient experiments are performed, demonstrating that this approach is highly efficient in detecting small brain metastases.