Feasibility and optimization of ultra-short echo time MRI for improved imaging of IVC-filters at 3.0 T

PURPOSE: To determine the feasibility of ultra-short echo time (UTE) MRA for assessment of inferior vena cava (IVC) filters and evaluate the impact of different imaging protocols at 3.0 T, using conventional Cartesian MRA (cMRA) as the reference standard.

METHODS: Patients with IVC-filters were recruited for this prospective IRB-approved, HIPAA-compliant study. Subjects underwent contrast-enhanced breath-held and a free-breathing 3D radial acquisition UTE-MRA (bhUTE, fbUTE) at three different flip angles (FA: 10°, 15°, 20°) to optimize T1-weighted image quality. Two radiologists performed a direct comparison consensus reading to assess the optimal FA. Image quality (IQ) of both UTE techniques at the best FA was rated independently on a 4-point Likert scale (0 = non-diagnostic, 3 = excellent) and compared to 3D T1-weighted breath-held cMRA.

RESULTS: Nine subjects were recruited. Low FAs of 10° were rated best for both UTE techniques. fbUTE was excellent (3, IQR: 2; 3) and significantly better for IVC-filter depiction than cMRA (2, IQR: 0.75; 2, p = 0.001) and bhUTE (1.5, IQR: 0.75; 2, p < 0.001). Both UTE techniques showed significantly less filter-related artifacts (fbUTE: 28%, bhUTE: 33%) than cMRA (89%, p = 0.001 and p = 0.002, respectively). However, IQ of bhUTE was generally degraded due to high image noise and low image contrast. IQ of the IVC venogram was best with cMRA. Clinically relevant signal voids were only observed with the cage-shaped OptEase filter.

CONCLUSION: UTE-MRA is feasible at 3.0 T for the assessment of IVC-filters, particularly using a free-breathing protocol. Larger studies are needed to investigate the clinical utility of free-breathing UTE-MRA for assessment of IVC-filter-related complications.