Max CAPR: High‐resolution 3D contrast‐enhanced MR angiography with acquisition times under 5 seconds

Abstract

High temporal and spatial resolution is desired in imaging of vascular abnormalities having short arterial-to-venous transit times. Methods that exploit temporal correlation to reduce the observed frame time demonstrate temporal blurring, obfuscating bolus dynamics. Previously, a Cartesian acquisition with projection reconstruction-like (CAPR) sampling method has been demonstrated for three-dimensional contrast-enhanced angiographic imaging of the lower legs using two-dimensional sensitivity-encoding acceleration and partial Fourier acceleration, providing 1mm isotropic resolution of the calves, with 4.9-sec frame time and 17.6-sec temporal footprint. In this work, the CAPR acquisition is further undersampled to provide a net acceleration approaching 40 by eliminating all view sharing. The tradeoff of frame time and temporal footprint in view sharing is presented and characterized in phantom experiments. It is shown that the resultant 4.9-sec acquisition time, three-dimensional images sets have sufficient spatial and temporal resolution to clearly portray arterial and venous phases of contrast passage. It is further hypothesized that these short temporal footprint sequences provide diagnostic quality images. This is tested and shown in a series of nine contrast-enhanced MR angiography patient studies performed with the new method.

Prospective Comparison of Cartesian Acquisition with Projection-like Reconstruction Magnetic Resonance Angiography with Computed Tomography Angiography for Evaluation of below-the-Knee Runoff

“…CAPR MRA followed a previously described technique: 20 mL gadobenate dimeglumine (Multihance, Bracco Imaging, Princeton, New Jersey, USA) injected at 3 ml/sec followed by 20 ml saline at 3 ml/sec (12). Imaging was performed on a 3T scanner (Signa v. 20.0, GE Healthcare, Waukesha, Wisconsin, USA) using a custom eight-element receive array coil designed in-house (13).…”

“…(11-13) The high acceleration provided by 2D SENSE and partial Fourier acceleration, as allowed by the specialized receiver coils, enables imaging the distal runoff vessels with 1 mm isotropic spatial resolution and a frame time of 4.9 sec, and has been shown to provide high fidelity in imaging an advancing contrast bolus. (14) Initial implementation has demonstrated that this technique can be successfully employed to evaluate lower extremity arterial vasculature (12). In this current work we sought to prospectively compare the degree of stenosis assessed by CAPR and CTA, as well as the confidence of the radiologist when evaluating patients with known or suspected peripheral vascular disease with both CAPR and CTA exams performed at our institution.…”

Recent advances in 3D time-resolved contrast-enhanced MR angiography

“…As portrayed in Fig. , the performance has improved due to many techniques previously identified in this work . Acquisition parameters for a number of these recent reports are listed in Table , and performance noted in Fig.…”

Time‐resolved bolus‐chase MR angiography with real‐time triggering of table motion

“…Because of the lack of prior image updates, the three initial reconstructed time frames (I5–I7) at the distal station have incomplete sampling of the k Y – k Z plane. However, it has been observed that even without view sharing the image updates can still have good quality (17, 18). Sampling of all four vane sets is done for image I8 and all subsequent frames.…”