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

Abstract

Purpose To prospectively compare the assessment of stenosis and radiologist confidence in the evaluation of below the knee lower extremity runoff vessels between computed tomographic angiography (CTA) and contrast enhanced magnetic resonance angiography (MRA) in a cohort of 19 clinical patients. Materials and Methods Our study was HIPAA compliant and IRB-approved. 19 consecutive patients with known or suspected peripheral arterial disease were imaged with both CTA and a recently developed MRA technique performed within 24 hours of each other and prior to any therapeutic intervention. Resulting images were randomized and interpreted in blinded fashion by four board certified radiologists with expertise in CTA and MRA. Vasculature of the lower leg was apportioned into 22 segments, 11 for each leg. For each segment, degree of stenosis and confidence of diagnosis were each determined using a three-point scale. Differences between CTA and MRA were assessed for significance using pooled histograms which were analyzed using the Wilcoxon signed rank test. Results For assessment of stenosis, there was no difference in CTA vs. MRA for 20/22 segments. For confidence of diagnosis, assessment of popliteal arteries was superior on CTA compared to MRA (p<0.05). Confidence in assessment of both tibioperoneal trunks and the left proximal anterior tibial artery was not significantly different between CTA and MRA. Confidence in assessment of all other 17 segments was superior with MRA than CTA (p<0.02). Conclusion MRA using the method described here is a promising technique for evaluating lower extremity arterial runoff. MRA had an overall superior performance in radiologist confidence when compared to CTA for imaging runoff vessels below the knee.

Three-Station Three-dimensional Bolus-Chase MR Angiography with Real-time Fluoroscopic Tracking

“…Favorable scoring seemed to follow where disease was present, with MRA typically being advantageous for more distal disease and CTA being advantageous for proximal disease and where stents were located. The first of these is consistent with previous work directly comparing CE-MRA and CTA in imaging of the calves (22). Motion and acceleration artifacts at the abdomen-pelvis station and venous contamination at the calf-foot station in cases of rapid arterial-to-venous transit are the prime issues that next need to be addressed.…”

Cardiac MR elastography using reduced‐FOV, single‐shot, spin‐echo EPI

“…The image pairs were graded on a 5‐point ordinal scale from −2 to + 2, with −2 indicating a strong preference for the first image, +2 indicating a strong preference for the second image, and 0 representing no preference . The order of the rFOV and full‐FOV images in the pair was blinded to the readers.…”

Use of blood pool agents with steady‐state MRI to assess the vascular system

“…Steady‐state MRA yields isotropic, submillimeter voxels, allowing for multiplanar reconstruction and more accurate stenosis assessment when compared with conventional first‐pass MRA techniques, thereby allowing the radiologist to differentiate luminal thrombus from calcification, which helps guide treatment options . Recent studies have also demonstrated MRA to be superior to CE‐CT angiography for the evaluation of the below‐knee runoff arteries, particularly those that are diffusely narrowed and/or diffusely calcified …”

“…24 Recent studies have also demonstrated MRA to be superior to CE-CT angiography for the evaluation of the below-knee runoff arteries, particularly those that are diffusely narrowed and/or diffusely calcified. 25 Our current protocol using a Siemens Aera 1.5T machine includes time-resolved imaging using Time resolved angiography With Stochastic Trajectories (TWIST; Siemens Healthcare, Erlangen, Germany) with a blood pool agent. Initially, 2 mL (or 20% of the contrast volume) of gadofosveset trisodium (diluted 50:50 with normal saline) is injected at 1 cc/sec with a temporal resolution of 5 seconds, imaged for 24 cycles (120 sec postinjection) to visualize the calf vessels, followed by another 8 mL (or the remainder of the contrast volume) of diluted gadofosveset trisodium and a first-pass acquisition to visualize the larger vessels with the pelvis and thigh.…”