Neuroimaging is a critical element in evaluating and treating patients with cerebral aneurysms. Each neuroimaging technique has unique strengths, weaknesses, and current developments. In this review, we discuss the utility of two primary noninvasive radiological techniques-computed tomography angiography (CTA) and magnetic resonance angiography (MRA)-as well as of digital subtraction angiography (DSA) for evaluation of cerebral aneurysms. These techniques allow comprehensive evaluation of aneurysm size, location, rupture status, and other imaging characteristics that guide clinicians to make appropriate and timely treatment recommendations.

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Purpose Kinetic analysis using dynamic contrast enhanced MRI to assess neovascularization of carotid plaque requires images with high spatial and temporal resolution. This work demonstrates a new 3D dynamic contrast enhanced imaging sequence, which directly measures the arterial input function with high temporal resolution yet maintains the high spatial resolution required to identify areas of increased adventitial neovascularity. Theory and Methods The sequence consists of multiple rapid acquisitions of a saturation prepared dynamic 3D gradient recalled echo (GRE) sequence temporally interleaved with multiple acquisitions of a 2D slice. The saturation recovery time was adjusted to maintain signal linearity with the very different contrast agent concentrations in the 2D slice and 3D volume. The Ktrans maps were obtained from the 3D dynamic contrast measurements while the 2D slice was used to obtain the arterial input function. Calibration and dynamic studies are presented Results For contrast agent concentrations up to 5mM, a saturation recovery time for the 2D slice of 20ms resulted in less than a 10% deviation from the desired linear response of signal intensity with contrast agent concentration. The corresponding saturation recovery time of 83 ms for the 3D volume maintained less than a 10% deviation from the linear response up to contrast agent concentrations of 2mM while a contrast agent concentration of 5mM had almost a 30% deviation. There was a significant improvement in signal attenuation (9±3% vs 23±5% at 40cm/s) when flow compensation was added to the slice select gradients. For patient studies, volume transfer and plasma fraction maps were calculated with data from the proposed sequence. Conclusions This work demonstrated a novel sequence for 3D dynamic contrast enhanced imaging with a simultaneously acquired 2D slice that directly measures the arterial input function with high temporal resolution. Acquisition parameters can be adjusted to accommodate the full range of contrast agent concentration values to be encountered and the kinetic parameters obtained were consistent with expected values.

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