Intravenous Line Phase-Wrap Artifact at Bilateral Axial 3-T Breast MRI: Identification, Analysis, and Solution

Abstract

Purpose: To understand and remove the source of a phase-wrap artifact produced by residual contrast agent in the intravenous line during acquisition of bilateral axial 3-T dynamic contrast material-enhanced (DCE) breast MRI.

Materials and methods: A two-part study involved a phantom experiment, followed by an institutional review board approved clinical intervention, to evaluate the phase-wrap artifact at MRI. A phantom model evaluated artifact production by using an intravenous line filled with fluids with varying concentrations of gadolinium-based contrast agent (0, 0.4, 0.8, 1.2, 1.6, and 2 mmol/mL) and by positioning the simulated intravenous line within several fields of view (FOV) at 3-T MRI in breast coils. Next, a clinical assessment was performed with a total of 400 patients (control group:interventional group, 200:200) to determine the effect of taping the intravenous line to the patients' backs. Breast MR images were assessed blindly for the presence of the artifact. Software was used for statistical analysis with a P value of less than .05 considered a significant difference.

Results: In the phantom model, the artifact was produced only with a 0.4 mmol/mL gadolinium concentration and when the tubing was either close to the edge or within a FOV of 350-450 mm. In the clinical experiment, the artifact was more prevalent in the retrospective control group than in the prospective intervention group (52.5% [105 of 200] vs 22% [44 of 200]; P < .005).

Conclusion: The presence of phase-wrap artifacts can be reduced by moving the contrast agent intravenous line out of the FOV during acquisition by taping it to a patient's back during bilateral axial 3-T DCE breast MRI.Keywords: Breast, MR-Imaging, Phantom Studies© RSNA, 2020.

Figure 1:

Image of the phantom experimental model. Two bottles of nickel sulfate solution were inserted into the dedicated breast coil. A long plastic tubing line, identical to the clinical tubing used for injection, was taped to a cushion and placed at the edge of the breast coil (arrow) and filled with fluids with different concentrations of gadolinium. The entire phantom was inserted into the clinical scanner and images were obtained.

Figure 2:

Illustration of patient positioning within the MR scanner in prone head-first orientation with arms above the head. (a) The long intravenous line extends caudally through the MR tunnel alongside the body and may fall into the field of view, ending at a power injector outside of the MR machine located next to the patient’s legs. (b) The intravenous line tubing was routinely taped to the patient’s back in the region of the scapula on the ipsilateral side to the injection line insertion.

Figure 3:

MR images in a 42-year-old woman who is a carrier of the BRCA mutation for routine annual screening. A, First axial T1-weighted three-dimensional volumetric interpolated breath-hold examination image after contrast agent administration (cropped to right breast only) shows no abnormality. B, The same patient imaged at a routine surveillance examination 1 year later. A small well-defined, hyperintense nodule (solid white arrow) appears in the right upper inner breast which was erroneously interpreted as a suspicious focus of enhancement. C, Same image as B, however, uncropped image of both breasts, shows the suspicious focus (solid white arrow) and an identical finding lateral to the left breast (broken white arrow) revealing the true artifactual nature of the abnormality. The intravenous injection line was placed in the left hand, causing signal close to the edge of the field of view on the left (solid white arrow) which wrapped around to overlay the right breast (solid white arrow). A vague wrap-around of the left breast contour is also evident on the image to the right of the right breast (arrowhead).

Figure 4:

MR images of the phantom model demonstrate appearance of the artifact on a single axial T1-weighted three-dimensional volumetric interpolated breath-hold examination image. In both images, the tubing was placed in an identical position to the right of the breast coil and filled with an 0.04 mmol/mL gadolinium solution. A, The field of view (FOV) is 360 mm, and the line is outside of the FOV. An artifact is noted overlying the superficial medial portion of the left phantom bottle (white arrow). B, The FOV is 450 mm, and the line is folded and inside the FOV (white arrowhead). The artifact is again noted (curved white arrow), this time overlaying the central portion of the left phantom bottle.

Figure 5:

Axial maximum intensity projection reconstructions of bilateral breast MRI examinations performed as routine surveillance in a 44-year-old woman with elevated risk. A, Image obtained 1 year prior to the current experiment, when the intravenous line was not taped to the shoulder. A tubular artifact in the anterior half of the image, overlaying the medial edge of the right breast (solid white arrow) is noted. B, The same patient and orientation imaged 1 year later with taping the intravenous line to the shoulder. The artifact was again generated as a tubular finding; however, this time it is in the posterior half of the image and does not overlay the breast (curved white arrow).