CC BY-NC-ND 4.0 · Indian J Radiol Imaging 2025; 35(02): 263-271
DOI: 10.1055/s-0044-1791491
Original Article

Safety Clearance and Artifact Testing of a Nitinol Breast Biopsy Clip in an Ultra-High Resolution (7 Tesla) Magnetic Resonance Imaging Environment

William Dong
1   Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
,
Kanchna Ramchandran
1   Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
,
Adam E. Galloy
2   Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, Iowa, United States
,
Marco A. Nino
2   Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, Iowa, United States
,
Marla Kleingartner
3   Magnetic Resonance Research Facility, University of Iowa, Iowa City, Iowa, United States
,
John Piaszynski
1   Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
,
Madhavan L. Raghavan
2   Roy J. Carver Department of Biomedical Engineering, College of Engineering, University of Iowa, Iowa City, Iowa, United States
,
Sneha Phadke
1   Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
,
Vincent A. Magnotta
4   Department of Radiology, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States
› Author Affiliations
Funding We would also like to acknowledge the Fraternal Order of Eagles Cancer Fund, for supporting this research. We would like to acknowledge the funding from NIH in support of the scanner used to collect these data (grant no.: S10RR028821). V.A.M. receives partial salary support from the NIH P50HD103556 grant. K.R. received partial salary support from the Benz grant from the Holden Comprehensive Cancer Center during this study. W.D. received scholarship funding from the University of Iowa's Maximizing Access to Research Careers Program, funded by NIH (grant no.: T34GM141143).
 

Abstract

Background The lack of safety clearance of several metallic breast biopsy clips in 7 Tesla (T) poses a significant hurdle to using advanced magnetic resonance imaging (MRI) techniques in clinical management or cancer research.

Aims This article assesses the Ultracor Twirl clip for safety and imaging artifacts in a 7T MRI scanner.

Setting and Design This study can be categorized as a phantom study.

Materials and Methods Tests for magnetic susceptibility (translational attraction and torque), MRI-related heating, and artifacts were conducted based on the American Society for Testing and Materials standards. The magnetic susceptibility tests evaluated the scanner's magnetic force that can cause clip movement and rotation. The heating test was conducted with customized MRI parameters of short TR and maximum echo-train length, designed to induce temperature change. The artifact test, using T1-weighted spin and gradient echo imaging sequences, evaluated potential image misrepresentations (localized signal loss) caused by the clip's metallic properties.

Statistical Tests None.

Results and Conclusion The magnetic susceptibility tests indicated no noticeable translational or rotational force exerted by the MRI scanner. The heating test indicated no significant temperature change (<0.3°C) in the testing gel when the clip was absent/present, both within the safety threshold (<1°C). The artifact test's clip images all contained an artifact (largest radius = 10.7 mm). These cumulative results indicate that this clip is safe in 7T scanners. Scanning at least 10.7 mm away from the clip avoids potential signal loss in the region of interest.


#

Introduction

Breast biopsy clips used in clinical management and research involving breast cancer patients and survivors, imaged in 1.5T (Tesla) and 3T field strength magnetic resonance imaging (MRI) environments,[1] [2] have been tested and cleared for safety. With the Food and Drug Administration's approval and application of 7T MRI,[3] [4] ultra-high resolution imaging may be utilized in clinical management and research studies in these groups. Higher field strengths such as 7T offer a higher intrinsic signal-to-noise ratio with resultant superior spatial and/or temporal resolution[5] as compared to 3T and lower field scanners. Novel imaging techniques for accurate diagnostics are possible in 7T[6] with magnetic resonance spectroscopy being one of the modalities, which has clear benefits at higher fields. 7T provides excellent image quality of malignant breast mass lesions with a significant increase in reader confidence.[7] Fat-corrected relaxation-compensated and chemical exchange saturation transfer MRI in 7T shows promise in contrast-free, noninvasive differentiation between breast cancer and normal-appearing fibroglandular breast tissue,[8] and serves as a noninvasive biomarker to assess the early-stage efficacy of neoadjuvant chemotherapy.[9] Dynamic contrast-enhanced MRI of the breast is feasible,[10] providing the ability to differentiate between benign and malignant lesions. Thus, 7T MRI shows promise in advancing noninvasive, accurate, contrast-free diagnostic imaging in breast cancer.

Magnetic forces, heating, and artifact effects are greater at 7T as compared to lower-field MRI systems.[11] A limited sample of biopsy clips have been tested in 7T,[12] [13] and many clips remain untested at this high field strength. If the safety of breast biopsy clips is demonstrated in 7T scanners, it will allow the use of ultra-high field MRI in routine clinical management or research studies of breast cancer.

A nitinol[14] breast biopsy clip (Ultracor Twirl, Becton, Dickinson and Company, Vernon Hills, Illinois, United States) was tested in this investigation since the clip is metallic and has received safety clearance for 3T[13] but not 7T MRI. The clip, frequently used in breast cancer biopsies due to its good ultrasound visibility,[15] [16] [17] is ring-shaped, 4-mm in diameter, 1-mm thick, and weighs 0.0196 g. This project aims to determine the safety and artifact size of the clip via translational attraction, torque, induced heating, and artifact tests in 7T MRI (GE 950 Whole Body Scanner).


#

Materials and Methods

This study did not require oversight from the Institutional Review Board, because no human subjects were involved. This is not a rater study and all images collected in this study were obtained in phantoms. The translational attraction,[18] torque,[19] induced heating,[20] and artifact[21] tests were all performed according to the American Society for Testing and Materials (ASTM) standards. The setups for testing were illustrated in the figures ([Figs. 1] [2] [3] [4]) since close-up photos were unsafe to obtain in the magnetic environment of the scanner.

Zoom Image
Fig. 1 Translational attraction test setup. (A) The clip was suspended at the scanner entrance, adjacent to a protractor. This location has the strongest human subject-accessible spatial field gradient. The black circle is the clip. (B) Close-up view of (A).
Zoom Image
Fig. 2 Torque test setup. (A) The acrylic sheet was inclined until the biopsy clip almost slipped. (B) The clip was assessed in all 8 orientations at the center of the scanner by rotating the clip at each 45-degree increment about the center. (C) Close-up view of (B).
Zoom Image
Fig. 3 Induced heating test setup. (A) The first run determined the probe location with the greatest temperature change. The second run (control, same setup) observed the gel's temperature change at the test location. (B) Close-up view of (A). (C) The third run (clip-present) observed the clip's temperature change at the test location. (D) Close-up view of (C).
Zoom Image
Fig. 4 Artifact test setup. (A) The clip was imaged in the parallel configuration. (B) Close-up view of (A). (C) The clip was imaged in the perpendicular configuration. (D) Close-up view of (C).

Translational Attraction Test

This test measured the 7T MRI scanner's magnetic force on the biopsy clip. The Ultracor Twirl clip was suspended by a 10-cm string (Meiyi Nylon Monofilament Non-Absorbable Synthetic Suture [0.00174 g]) next to a protractor mounted on a cardboard box. The setup, placed at the scanner's opening (1.82 m from the isocenter; [Fig. 1]), indicated the string's deflection angle toward the scanner bore. The deflection angle allowed the estimation of the magnetic force relative to the gravitational force. The chosen test location was estimated to have the highest spatial gradient magnetic field ([Supplementary Fig. S1], available in the online version) and force, thus representing the most stringent conditions for translational attraction.


#

Torque Test

This test measured the torque exerted on the biopsy clip by the 7T MRI scanner. The Ultracor Twirl clip was placed on a low-friction acrylic sheet and inclined to the maximum angle that the clip could stay in place without sliding off ([Fig. 2A]). The incline angle was used to calculate the maximum torque.[19] The clip was then inserted into the scanner's isocenter ([Fig. 2]), following the ASTM standard's method.[19]

Since the clip did not move during the torque test procedure, the maximum torque derived from the incline test was compared to the gravitational torque on the clip. The gravitational torque about the clip's longest edge is the cross product of the distance from the clip's longest edge to the center of mass and the gravitational force (weight). Since the clip is a ring, the center of mass and distance were estimated to be at the center of the ring and half the clip's length, respectively. The torque peaks when the gravitational force is perpendicular to the length. Therefore, the maximum gravitational torque was estimated with the following equation:

Zoom Image

where τ is the induced torque, m is the mass of the clip, g is the gravitational acceleration constant, and L is the longest length across the clip.


#

Induced Heating Test

This test measured the radiofrequency coil's (2Tx/32Rx head radiofrequency coil) heating effect on the clip in a gel medium comprising of 1.32 g/L NaCl, 10 g/L partial sodium polyacrylic acid, and 1 L water. The gel conductivity was verified to be within 0.47 ± 10% S/m, which simulated human body conditions. This test was performed inside the scanner, using a fiber optic thermometer. Three temperature probes were placed in a line parallel to the bore inside the gel ([Fig. 3A]). A test run measured the temperature change over time at each probe. The probe where the greatest radiofrequency exposure (greatest temperature change) occurred was designated as the heating probe. During the heating test, the clip-present and control (clip-absent) runs measured the temperature change over time at the heating probe. The other two (middle and edge) probes served to validate that both runs received similar radiofrequency exposure. The heating test ([Fig. 3A] and [C]) was performed with a modified duration of 8 minutes 36 seconds for each round. The following MRI parameters maximized heating effects[20]: two-dimensional fast spin-echo, field of view (FOV) = 220 × 198 mm, slice thickness/spacing = 5/1 mm, TR = 4,000 ms, TE = 5.5 ms, echo train length = 16, matrix = 416 × 256, NEX = 8, bandwidth = 781.25 Hz/pixel, time = 8:36. The specific absorption rate (SAR) of each run was calculated using the slope of the temperature versus time graph and evaluated for safety based on [Eq. (1)] in the ASTM standard.[20]


#

Artifact Test

This test measured the size of the artifact, caused by the metallic properties of the clip. A 3.7-L solution of 1.5 g/L CuSO4 was created and separated into three plastic containers (10 cm·10 cm·10 cm) to immerse the biopsy clip. The first container had a nylon rod (reference object) suspended from the top of the container. The second and third containers had clips suspended with their longest length parallel and perpendicular to the scanner's static field. During the test, the second or third container was placed above the first ([Fig. 4A] and [C]). The artifact test was performed inside the scanner by imaging the clip in orientations and conditions ([Tables 1] and [2]) described by the standard (perpendicular/parallel to the static field, frequency/phase encode directions, spin/gradient echoes, and presence/absence of the clip).[21] The MRI scans included spin-echo (TR = 500 ms, TE = 20 ms, FOV = 120 mm, matrix = 256 × 256, bandwidth = 244.141 Hz/pixel, slice thickness = 3 mm) and gradient-echo (TR = 200 ms, TE = 5.5 ms, FOV = 120 mm, matrix = 256 × 256, bandwidth = 244.141 Hz/pixel, slice thickness = 3 mm).

Table 1

Artifact test conditions

Image set

Image view

Clip orientation relative to static field

Frequency encode direction

Echo

Clip presence

Compared to image set(s)

1

Sagittal

Perpendicular

SI

Spin

Present

12

2

Sagittal

Perpendicular

AP

Spin

Present

12

3

Sagittal

Perpendicular

SI

Gradient

Present

11

4

Sagittal

Perpendicular

AP

Gradient

Present

11

5

Axial

Perpendicular

AP

Gradient

Present

9

6

Axial

Perpendicular

RL

Gradient

Present

9

7

Axial

Perpendicular

AP

Spin

Present

10

8

Axial

Perpendicular

RL

Spin

Present

10

9

Axial

Perpendicular

AP

Gradient

Absent

5, 6

10

Axial

Perpendicular

AP

Spin

Absent

7, 8

11

Sagittal

Perpendicular

AP

Gradient

Absent

3, 4

12

Sagittal

Perpendicular

AP

Spin

Absent

1, 2

13

Coronal

Perpendicular

SI

Gradient

Present

17

14

Coronal

Perpendicular

RL

Gradient

Present

17

15

Coronal

Perpendicular

SI

Spin

Present

18

16

Coronal

Perpendicular

RL

Spin

Present

18

17

Coronal

Perpendicular

RL

Gradient

Absent

13, 14

18

Coronal

Perpendicular

RL

Spin

Absent

15, 16

19

Sagittal

Parallel

SI

Gradient

Present

27

20

Sagittal

Parallel

AP

Gradient

Present

27

21

Sagittal

Parallel

SI

Spin

Present

28

22

Sagittal

Parallel

AP

Spin

Present

28

23

Axial

Parallel

AP

Gradient

Present

29

24

Axial

Parallel

RL

Gradient

Present

29

Abbreviations: AP, anteroposterior; RL, right-to-left; SI, superoinferior.


Table 2

Artifact test conditions

Image set

Image view

Clip orientation relative to static field

Frequency encode direction

Echo

Clip presence

Compared to image set(s)

25

Axial

Parallel

AP

Spin

Present

30

26

Axial

Parallel

RL

Spin

Present

30

27

Sagittal

Parallel

AP

Gradient

Absent

19, 20

28

Sagittal

Parallel

AP

Spin

Absent

21, 22

29

Axial

Parallel

AP

Gradient

Absent

23, 24

30

Axial

Parallel

AP

Spin

Absent

25, 26

31

Coronal

Parallel

SI

Gradient

Present

35

32

Coronal

Parallel

RL

Gradient

Present

35

33

Coronal

Parallel

SI

Spin

Present

36

34

Coronal

Parallel

RL

Spin

Present

36

35

Coronal

Parallel

RL

Gradient

Absent

31, 32

36

Coronal

Parallel

RL

Spin

Absent

33, 34

Abbreviations: AP, anteroposterior; RL, right-to-left; SI, superoinferior.


The clip-present images were compared to clip-absent (control) images based on the same image view, clip orientation, and echo type. For example, image set 1 was compared with image set 12 ([Tables 1] and [2]). Image registration using the Advanced Normalization Tools Software[22] corrected minor image misalignment between the compared images. The registration settings utilized rigid transformation and artifact masking. Histogram matching between the compared images was performed in MATLAB R2022a-Image Processing Package (The MathWorks, Inc., Natick, Massachusetts, United States) using 64 bins, to address the signal intensity variations between the images. Comparisons between artifact-present and artifact-absent images were made for each voxel on every slice, generating binary images based on a 30% difference threshold defined by the standard.[21] [23] The artifact size was measured in signal-loss radius and volume. The radius was measured from the artifact centroid to the artifact's furthest edge on each slice. The largest of these radii was selected for each image. The volume was measured by summing the image set's artifact volume in each slice.


#
#

Results

Provided below are results from the translational attraction, torque, heating, and artifact tests.

Translational Attraction Test

The fringe field map indicated that the highest spatial gradient magnetic field location was 8.26 T/m at 1.82 m from the isocenter along the z-axis, which determined the testing location. The test resulted in a 0-degree deflection angle, indicating that the marker was not impacted by the scanner's magnetic force. This demonstrated the clip's safety since the ASTM standard indicates that if the test's deflection angle is less than 45 degrees, the magnetically induced force on the clip is less than the gravity and therefore generally safe.[18]


#

Torque Test

The torque test demonstrated no clip movement in all 45-degree increment orientations. Since the torque test was performed on a surface with a coefficient of friction of 0.364, the maximum magnetic torque was 2.80 × 10−6 Nm. The ASTM standard defined safe torque induced by the scanner as less than the torque from regular daily activities such as riding vehicles or amusement park rides.[19] The Food and Drug Administration defined safe torque as less than gravitational torque.[24] The maximum magnetic torque was less than the gravitational torque about the axis perpendicular to the clip's edge (3.85 × 10−6 Nm), which demonstrated the clip's safety.


#

Induced Heating Test

Prior to the heating test, the test run recordings from the probes indicated that the greatest radiofrequency exposure occurred at the probe located closest to the radiofrequency coil's center (heating probe). The induced heating test resulted in temperature changes of less than 0.3°C in 8 minutes 36 seconds for both the control and clip-present runs. The heating test probe's SARs for the control and clip-present runs were 2.02 and 1.84 W/kg, respectively. In the temperature change versus time graphs, the slope of the curve is consistent throughout the test ([Fig. 5]). This consistency was expected if the test were to continue to 15 minutes (the standard duration of the test), justifying the reduction in test duration. A conservative safety criterion for the induced heating test is that the clip heating should not exceed 1°C. If the test were to continue to 15 minutes, the projected temperature change would be less than 0.6°C (less than the safety threshold), indicating the clip's safety. The heating probe's similar temperature changes in both the control and clip-present runs ([Fig. 5A]) also indicated the clip's negligible effect on heating. The middle probe experienced a different temperature change between runs ([Fig. 5B]), and the edge probe experienced consistent, low temperature change in both runs ([Fig. 5C]).

Zoom Image
Fig. 5 Change in temperature vs. time graphs of the heating test. (A) The heating test probe's temperature vs. time graph indicating similar specific absorption rates. (B) The middle control probe's temperature vs. time graph indicating different specific absorption rates. (C) The edge control probe's temperature vs. time graph indicating similar specific absorption rates.

#

Artifact Test

The artifact test indicated that the clip causes a minor signal-loss artifact in MR images ([Supplementary Fig. S2], available in the online version). The spin echo images produced smaller artifacts (up to 342.8  mm3 in volume and 6.0 mm in radius), compared to the gradient echo images (up to 2,235.9 mm3 and 10.7 mm in radius; [Table 3]).

Table 3

Artifact test size results

Image set

Artifact volume (mm3)

Artifact width (mm)

1

221.5

3.9

2

203.0

4.8

3

1,943.3

8.5

4

1,938.0

8.6

5

2,088.3

8.1

6

2,032.9

8.2

7

232.0

4.1

8

195.1

4.2

13

2,011.8

10.0

14

2,011.8

10.1

15

150.3

4.1

16

137.1

4.3

19

1,922.2

8.7

20

1,898.4

8.9

21

60.6

2.6

22

18.5

1.4

23

2,235.9

8.3

24

2,209.6

8.3

25

342.8

4.7

26

327.0

4.9

31

2,148.9

10.7

32

2,048.7

9.9

33

242.6

6.0

34

187.2

4.7

Overall, the translational attraction, torque, and induced heating tests indicated that the clip is safe in terms of magnetic susceptibility and radiofrequency heating effects. The artifact test indicated that the clip could produce a small signal-loss artifact in the surrounding area.


#
#

Discussion

This research suggests that 7T MRI scanning is safe for human subjects with the Ultracor Twirl implant, while also demonstrating signal-loss artifacts associated with the clip. In a similar study by Shellock and colleagues,[12] 8 metallic breast biopsy clips (titanium or stainless steel) were tested and cleared as safe in 7T. The methods used in the current research are similar, except for the torque test. Shellock and colleagues[12] classified torque via observation and rating the torque from 0 to 4, with 0 indicating no torque and 4 indicating strong torque. In contrast to Shellock and colleagues,[12] the current research compares the maximum magnetic torque with the Food and Drug Administration-defined safety threshold (gravitational torque).[24]

Translational Attraction Test

In the translational attraction test, the ASTM standard recommends the string material for clip suspension to be less than 1% of the clip's mass. However, finding a string light enough was impractical, thus motivating the use of a 10% threshold. This has been previously used in a lightweight implant safety test in 3T scanning.[1] With this modification, the deflection angle measured was 0 degrees, indicating that no magnetic force was detected. The positional setup of this experiment represents the most stringent conditions of the magnetic force that may be experienced by a human subject. The force peaks at the entrance of the scanner.[11]


#

Torque Test

In the torque test, safety is determined by comparing the maximum magnetic torque and the gravitational torque of the clip. The gravitational torque of the clip represents the scenario where one side of the clip is attached to the tissue and the rest of the clip dangles downward. It is greater than the greatest torque from the 7T scanner, which fulfills the conservative safety criterion. Additionally, using the torque classifications from Shellock and colleagues,[12] this clip has a 0 rating since no movement was observed during the test. This rating is consistent with the translational attraction test result, supporting the clip's safety in magnetic susceptibility.


#

Induced Heating Test

As highlighted in the heating test results, the heating and edge probes experienced similar temperature changes in both the control and clip-present runs, whereas the middle probe experienced different temperature changes. The middle probe region is expected to receive consistent radiofrequency exposure in both runs. The deviation may be due to the movement of the probe away from a radiofrequency hotspot when the clip was being inserted during the clip-present run. The edge probe's consistent, low temperature change in both runs is expected since the region received the same radiofrequency exposure in both runs. The induced heating test has not been performed in the 7T environment for breast biopsy clips in prior research[12] because body coils are not available for these scanners. Hence, we opted to perform this test using a 2Tx/32Rx head coil. Parallel transmission was not used during this test, so the clip may require reevaluation for MRI applications utilizing parallel transmission. This test simulates the highest heating in neuroimaging applications since the clip is located inside the head coil. Normally, the clip is located inside the breast and away from the radiofrequency exposure, and thus would experience less heating.


#

Artifact Test

In the artifact test, the image processing registration settings (rigid registration and masking) improved the accuracy of artifact size measurement by avoiding artifact deformation and registering only the relevant features. The histogram matching using 64 bins reduced the signal intensity variation in the images attributed to the scanner avoiding signal clipping. This allows the 30% threshold comparison to represent the signal-loss artifact size more accurately. The results indicate that the largest signal-loss artifact occurs when using gradient echo. If the clip is located at least 10.7 mm away from the region of interest, potential signal loss would not affect the region of interest. Artifact size is independent of the 7T coil type, and hence this result is invariant with both head and body coils.


#

Possible Limitations and Future Directions

The translational attraction, heating, and artifact tests in this study have some limitations that may be addressed by future research. In the translational attraction test, using the 10% string weight threshold may underrepresent the measured force since the string's greater relative weight would contribute toward resisting the magnetic force.

A literature search for the artifacts, SAR, and heat indicator at 3T did not yield these details, although the clip's safety clearance is available at.[13] If readily available, this information would have facilitated a comparison of these measures between 3T and 7T, which may be of relevance to clinicians. Our 7T research facility did not have access to a breast coil, and hence these results may bear replication in future studies with a 7T breast coil. In the future, it is necessary for safety and artifact testing of other biopsy clips and related implants at 7T[13] to gain traction, in order for ultra-high resolution imaging to be more accessible to breast cancer clinical and research use.


#
#

Conclusion

This research suggests that the Ultracor Twirl clip is safe for use in ultra-high resolution MRI (7T). The safety clearance is significant in allowing human subjects with this clip to be scanned in Food and Drug Administration-approved ultra-high-field (7T) MRI scanners. The artifact test indicates that the clip can produce a small signal-loss artifact to a maximum of 10.7 mm.


#
#

Conflict of Interest

None declared.

Acknowledgments

At the University of Iowa, we would like to acknowledge the following resources: Dr. Mubeen (Department of Chemical and Biochemical Engineering) and his lab for assisting us in ascertaining the weight of the clip; and Conner Wharff at the Magnetic Resonance Research Facility in assisting with imaging the clip.

There are no relevant commercial disclosures with regard to this research.

A significant portion of this research was presented as a poster at the San Antonio Breast Cancer Symposium (2022). https://doi.org/10.1158/1538-7445.SABCS22-P3-04-07 .

Note

This work is attributed to the Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa, United States.


Supplementary Material

  • References

  • 1 Cronenweth CM, Shellock FG. Assessment of MRI issues at 3 Tesla for a new metallic tissue marker. Int J Breast Cancer 2015; 2015: 823759
  • 2 Shellock FG. Metallic marking clips used after stereotactic breast biopsy: ex vivo testing of ferromagnetism, heating, and artifacts associated with MR imaging. AJR Am J Roentgenol 1999; 172 (05) 1417-1419
  • 3 U.S. Food and Drug Administration. FDA clears first 7T magnetic resonance imaging device. 2017
  • 4 Rutland JW, Delman BN, Gill CM, Zhu C, Shrivastava RK, Balchandani P. Emerging use of ultra-high-field 7T MRI in the study of intracranial vascularity: state of the field and future directions. AJNR Am J Neuroradiol 2020; 41 (01) 2-9
  • 5 Menezes GL, Stehouwer BL, Klomp DW. et al. Dynamic contrast-enhanced breast MRI at 7T and 3T: an intra-individual comparison study. Springerplus 2016; 5 (01) 1-12
  • 6 Bougias H, Stogiannos N. Breast MRI: where are we currently standing?. J Med Imaging Radiat Sci 2022; 53 (02) 203-211
  • 7 Stehouwer BL, Klomp DW, van den Bosch MA. et al. Dynamic contrast-enhanced and ultra-high-resolution breast MRI at 7.0 Tesla. Eur Radiol 2013; 23 (11) 2961-2968
  • 8 Loi L, Zimmermann F, Goerke S. et al. Relaxation-compensated CEST (chemical exchange saturation transfer) imaging in breast cancer diagnostics at 7T. Eur J Radiol 2020; 129: 109068
  • 9 Krikken E, Khlebnikov V, Zaiss M. et al. Amide chemical exchange saturation transfer at 7 T: a possible biomarker for detecting early response to neoadjuvant chemotherapy in breast cancer patients. Breast Cancer Res 2018; 20 (01) 51
  • 10 Ochoa-Albiztegui RE, Sevilimedu V, Horvat JV. et al. Pharmacokinetic analysis of dynamic contrast-enhanced magnetic resonance imaging at 7T for breast cancer diagnosis and characterization. Cancers (Basel) 2020; 12 (12) 3763
  • 11 Hoff MN, McKinney IV A, Shellock FG, Rassner U, Gilk T, Watson Jr RE, Greenberg TD, Froelich J, Kanal E. Safety considerations of 7-T MRI in clinical practice. Radiology 2019; 292 (03) 509-518
  • 12 Dula AN, Virostko J, Shellock FG. Assessment of MRI issues at 7 T for 28 implants and other objects. AJR Am J Roentgenol 2014; 202 (02) 401-405
  • 13 Shellock FG. The List. MRIsafety.com. 2023
  • 14 Combs J, Levin E, Cheng C, Daly S, Yeralan S, Duerig T. Effects of heat treatment on the magnetic properties of nitinol devices. Shape Mem Superelast 2019; 5: 429-435
  • 15 Portnow LH, Thornton CM, Milch HS, Mango VL, Morris EA, Saphier NB. Biopsy marker standardization: what's in a name?. AJR Am J Roentgenol 2019; 212 (06) 1400-1405
  • 16 Portnow LH, Kwak E, Senapati GM, Kwait DC, Denison CM, Giess CS. Ultrasound visibility of select breast biopsy markers for targeted axillary node localization following neoadjuvant treatment: simulation using animal tissue models. Breast Cancer Res Treat 2020; 184 (01) 185-192
  • 17 Lim GH, Teo SY, Gudi M. et al. Initial results of a novel technique of clipped node localization in breast cancer patients postneoadjuvant chemotherapy: Skin Mark clipped Axillary nodes Removal Technique (SMART trial). Cancer Med 2020; 9 (06) 1978-1985
  • 18 ASTM. F2052–15 Standard Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment. West Conshohocken, PA: ASTM International; 2015
  • 19 ASTM. F2213–17 Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment. West Conshohocken, PA: ASTM International; 2017
  • 20 ASTM. F2182–19 Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging. West Conshohocken, PA: ASTM International; 2019
  • 21 ASTM. F2119–07 Standard Test Method for Evaluation of MR Image Artifacts from Passive Implants. West Conshohocken, PA: ASTM International; 2013
  • 22 Avants BB, Epstein CL, Grossman M, Gee JC. Symmetric diffeomorphic image registration with cross-correlation: evaluating automated labeling of elderly and neurodegenerative brain. Med Image Anal 2008; 12 (01) 26-41
  • 23 Spronk T, Kraff O, Kreutner J, Schaefers G, Quick HH. Development and evaluation of a numerical simulation approach to predict metal artifacts from passive implants in MRI. MAGMA 2022; 35 (03) 485-497
  • 24 U.S. Food and Drug Administration. Testing and labeling medical devices for safety in the magnetic resonance (MR) environment. Draft guidance for industry and Food and Drug Administration Staff. 2019

Address for correspondence

William Dong, BSE
Department of Internal Medicine, Carver College of Medicine, University of Iowa
GH, 200 Hawkins Drive, Iowa City, Iowa 52242
United States   

Publication History

Article published online:
07 October 2024

© 2024. Indian Radiological Association. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)

Thieme Medical and Scientific Publishers Pvt. Ltd.
A-12, 2nd Floor, Sector 2, Noida-201301 UP, India

  • References

  • 1 Cronenweth CM, Shellock FG. Assessment of MRI issues at 3 Tesla for a new metallic tissue marker. Int J Breast Cancer 2015; 2015: 823759
  • 2 Shellock FG. Metallic marking clips used after stereotactic breast biopsy: ex vivo testing of ferromagnetism, heating, and artifacts associated with MR imaging. AJR Am J Roentgenol 1999; 172 (05) 1417-1419
  • 3 U.S. Food and Drug Administration. FDA clears first 7T magnetic resonance imaging device. 2017
  • 4 Rutland JW, Delman BN, Gill CM, Zhu C, Shrivastava RK, Balchandani P. Emerging use of ultra-high-field 7T MRI in the study of intracranial vascularity: state of the field and future directions. AJNR Am J Neuroradiol 2020; 41 (01) 2-9
  • 5 Menezes GL, Stehouwer BL, Klomp DW. et al. Dynamic contrast-enhanced breast MRI at 7T and 3T: an intra-individual comparison study. Springerplus 2016; 5 (01) 1-12
  • 6 Bougias H, Stogiannos N. Breast MRI: where are we currently standing?. J Med Imaging Radiat Sci 2022; 53 (02) 203-211
  • 7 Stehouwer BL, Klomp DW, van den Bosch MA. et al. Dynamic contrast-enhanced and ultra-high-resolution breast MRI at 7.0 Tesla. Eur Radiol 2013; 23 (11) 2961-2968
  • 8 Loi L, Zimmermann F, Goerke S. et al. Relaxation-compensated CEST (chemical exchange saturation transfer) imaging in breast cancer diagnostics at 7T. Eur J Radiol 2020; 129: 109068
  • 9 Krikken E, Khlebnikov V, Zaiss M. et al. Amide chemical exchange saturation transfer at 7 T: a possible biomarker for detecting early response to neoadjuvant chemotherapy in breast cancer patients. Breast Cancer Res 2018; 20 (01) 51
  • 10 Ochoa-Albiztegui RE, Sevilimedu V, Horvat JV. et al. Pharmacokinetic analysis of dynamic contrast-enhanced magnetic resonance imaging at 7T for breast cancer diagnosis and characterization. Cancers (Basel) 2020; 12 (12) 3763
  • 11 Hoff MN, McKinney IV A, Shellock FG, Rassner U, Gilk T, Watson Jr RE, Greenberg TD, Froelich J, Kanal E. Safety considerations of 7-T MRI in clinical practice. Radiology 2019; 292 (03) 509-518
  • 12 Dula AN, Virostko J, Shellock FG. Assessment of MRI issues at 7 T for 28 implants and other objects. AJR Am J Roentgenol 2014; 202 (02) 401-405
  • 13 Shellock FG. The List. MRIsafety.com. 2023
  • 14 Combs J, Levin E, Cheng C, Daly S, Yeralan S, Duerig T. Effects of heat treatment on the magnetic properties of nitinol devices. Shape Mem Superelast 2019; 5: 429-435
  • 15 Portnow LH, Thornton CM, Milch HS, Mango VL, Morris EA, Saphier NB. Biopsy marker standardization: what's in a name?. AJR Am J Roentgenol 2019; 212 (06) 1400-1405
  • 16 Portnow LH, Kwak E, Senapati GM, Kwait DC, Denison CM, Giess CS. Ultrasound visibility of select breast biopsy markers for targeted axillary node localization following neoadjuvant treatment: simulation using animal tissue models. Breast Cancer Res Treat 2020; 184 (01) 185-192
  • 17 Lim GH, Teo SY, Gudi M. et al. Initial results of a novel technique of clipped node localization in breast cancer patients postneoadjuvant chemotherapy: Skin Mark clipped Axillary nodes Removal Technique (SMART trial). Cancer Med 2020; 9 (06) 1978-1985
  • 18 ASTM. F2052–15 Standard Test Method for Measurement of Magnetically Induced Displacement Force on Medical Devices in the Magnetic Resonance Environment. West Conshohocken, PA: ASTM International; 2015
  • 19 ASTM. F2213–17 Standard Test Method for Measurement of Magnetically Induced Torque on Medical Devices in the Magnetic Resonance Environment. West Conshohocken, PA: ASTM International; 2017
  • 20 ASTM. F2182–19 Standard Test Method for Measurement of Radio Frequency Induced Heating On or Near Passive Implants During Magnetic Resonance Imaging. West Conshohocken, PA: ASTM International; 2019
  • 21 ASTM. F2119–07 Standard Test Method for Evaluation of MR Image Artifacts from Passive Implants. West Conshohocken, PA: ASTM International; 2013
  • 22 Avants BB, Epstein CL, Grossman M, Gee JC. Symmetric diffeomorphic image registration with cross-correlation: evaluating automated labeling of elderly and neurodegenerative brain. Med Image Anal 2008; 12 (01) 26-41
  • 23 Spronk T, Kraff O, Kreutner J, Schaefers G, Quick HH. Development and evaluation of a numerical simulation approach to predict metal artifacts from passive implants in MRI. MAGMA 2022; 35 (03) 485-497
  • 24 U.S. Food and Drug Administration. Testing and labeling medical devices for safety in the magnetic resonance (MR) environment. Draft guidance for industry and Food and Drug Administration Staff. 2019

Zoom Image
Fig. 1 Translational attraction test setup. (A) The clip was suspended at the scanner entrance, adjacent to a protractor. This location has the strongest human subject-accessible spatial field gradient. The black circle is the clip. (B) Close-up view of (A).
Zoom Image
Fig. 2 Torque test setup. (A) The acrylic sheet was inclined until the biopsy clip almost slipped. (B) The clip was assessed in all 8 orientations at the center of the scanner by rotating the clip at each 45-degree increment about the center. (C) Close-up view of (B).
Zoom Image
Fig. 3 Induced heating test setup. (A) The first run determined the probe location with the greatest temperature change. The second run (control, same setup) observed the gel's temperature change at the test location. (B) Close-up view of (A). (C) The third run (clip-present) observed the clip's temperature change at the test location. (D) Close-up view of (C).
Zoom Image
Fig. 4 Artifact test setup. (A) The clip was imaged in the parallel configuration. (B) Close-up view of (A). (C) The clip was imaged in the perpendicular configuration. (D) Close-up view of (C).
Zoom Image
Zoom Image
Fig. 5 Change in temperature vs. time graphs of the heating test. (A) The heating test probe's temperature vs. time graph indicating similar specific absorption rates. (B) The middle control probe's temperature vs. time graph indicating different specific absorption rates. (C) The edge control probe's temperature vs. time graph indicating similar specific absorption rates.