Robert R Edelman1,2, Nondas Leloudas3, Jianing Pang4, Julian Bailes5, Ryan Merrell6, and Ioannis Koktzoglou3,7
1Radiology, NorthShore University HealthSystem, EVANSTON, IL, United States, 2Feinberg School of Medicine, Northwestern University, Chicago, IL, United States, 3Radiology, NorthShore University HealthSystem, Evanston, IL, United States, 4Siemens Medical Solutions USA, Chicago, IL, United States, 5Neurosurgery, NorthShore University HealthSystem, Evanston, IL, United States, 6Medicine, NorthShore University HealthSystem, Evanston, IL, United States, 7Pritzker School of Medicine, University of Chicago, Chicago, IL, United States
1Radiology, NorthShore University HealthSystem, EVANSTON, IL, United States, 2Feinberg School of Medicine, Northwestern University, Chicago, IL, United States, 3Radiology, NorthShore University HealthSystem, Evanston, IL, United States, 4Siemens Medical Solutions USA, Chicago, IL, United States, 5Neurosurgery, NorthShore University HealthSystem, Evanston, IL, United States, 6Medicine, NorthShore University HealthSystem, Evanston, IL, United States, 7Pritzker School of Medicine, University of Chicago, Chicago, IL, United States
We describe a novel class of steady-state pulse sequence called T1RESS that provides excellent SNR and contrast, as well as flexible control of intravascular signal. For contrast-enhanced brain imaging, T1RESS demonstrated a remarkable two-fold improvement in tumor-to-brain contrast.
Fig. 1. A) T1RESS pulse sequence using balanced (top) and unbalanced (bottom) steady-state readouts. A non-spatially selective contrast-modifying RF pulse (CMα) is applied periodically over the entire duration of the echo train to introduce an arbitrary amount of T1 weighting. B) Phantom consisting of serial dilutions of gadobutrol imaged with bT1RESS using CMα values of 0o, 30o and 60o. Note that there is negligible T1 contrast for a CMα flip angle of 0o, but substantial T1 contrast is apparent as the flip angle is increased to 60o.
Fig. 2. Pulse sequence comparisons after contrast administration in a patient with metastatic melanoma. 10-mm thick axial (top) and coronal (bottom) maximum intensity projections are shown to highlight differences in lesion visibility for uT1RESS (left) and 3D spoiled GRE (right). Small metastatic lesions are much better visualized using uT1RESS than with 3D spoiled GRE. The combination of twofold increased tumor-to-background contrast, improved CNR and suppression of intravascular signals with uT1RESS is helpful to unambiguously identify small metastases.
