The implantable loop recorder and its mammographic appearance: A case based approach

Multimodality imaging in patients with implantable loop recorders: Tips and tricks

An implantable loop recorder (ILR) is a leadless rectangular device used for prolonged electrocardiographic monitoring for up to 3 years. This miniaturized device, inserted subcutaneously, allows clinicians to investigate possible cardiac rhythm disturbances in patients suffering from recurrent unexplained syncope. As the age of the population increases rapidly and the number of ILR patients amplifies, the clinical significance of ILRs is undeniable. Although radioopaque and easily seen on plain chest radiographs and other imaging modalities, ILRs may represent a challenge for clinicians and radiologists to recognize their classic appearance and differentiate them from numerous other cardiac devices. This article aims to summarize current literature on ILRs, their basic function, types, and indications for implantation, but most of all, it aims to familiarize clinicians and radiologists with common imaging features of these devices, safety issues, and artifact-reducing methods. Specifically, this review discusses the typical appearance of ILRs on major diagnostic imaging modalities, including chest X-ray, mammography, ultrasonography, computed tomography, and magnetic resonance imaging (MRI). Furthermore, optimization strategies to mitigate image artifacts and safety issues regarding MRI are discussed.

Breast MRI in patients with implantable loop recorder: initial experience

OBJECTIVES

To investigate the feasibility of breast MRI exams and guided biopsies in patients with an implantable loop recorder (ILR) as well as the impact ILRs may have on image interpretation.

MATERIALS AND METHODS

This retrospective study examined breast MRIs of patients with ILR, from April 2008 to September 2022. Radiological reports and electronic medical records were reviewed for demographic characteristics, safety concerns, and imaging findings. MR images were analyzed and compared statistically for artifact quantification on the various pulse sequences.

RESULTS

Overall, 40/82,778 (0.049%) MRIs during the study period included ILR. All MRIs were completed without early termination. No patient-related or device-related adverse events occurred. ILRs were most commonly located in the left lower-inner quadrant (64.6%). The main artifact was a signal intensity (SI) void in a dipole formation in the ILR bed with or without areas of peripheral high SI. Artifacts appeared greatest in the cranio-caudal axis (p < 0.001), followed by the anterior-posterior axis (p < 0.001), and then the right-left axis. High peripheral rim-like SI artifacts appeared on the post-contrast and subtracted T1-weighted images, mimicking suspicious enhancement. Artifacts were most prominent on diffusion-weighted (p < 0.001), followed by T2-weighted and T1-weighted images. In eight patients, suspicious findings were found on MRI, resulting in four additional malignant lesions. Of six patients with left breast cancer, the tumor was completely visible in five cases and partially obscured in one.

CONCLUSION

Breast MRI is feasible and safe among patients with ILR and may provide a significant diagnostic value, albeit with localized, characteristic artifacts.

CLINICAL RELEVANCE STATEMENT

Indicated breast MRI exams and guided biopsies can be safely performed in patients with implantable loop recorder. Nevertheless, radiologists should be aware of associated limitations including limited assessment of the inner left breast and pseudo-enhancement artifacts.

KEY POINTS

• Breast MRI in patients with an implantable loop recorder is an infrequent, feasible, and safe procedure. • Despite limited breast visualization of the implantable loop recorder bed and characteristic artifacts, MRI depicted additional lesions in 8/40 (20%) of cases, half of which were malignant. • Breast MRI in patients with an implantable loop recorder should be performed when indicated, taking into consideration typical associated artifacts.

Australian radiographers' awareness of cardiac implantable electronic devices (CIEDs) in mammographic imaging

INTRODUCTION

Women presenting for mammography occasionally have pacemakers or other cardiac-implantable electronic devices (CIEDs) in situ. This research investigates Australian radiographers' awareness of CIEDs in the diagnostic and screening settings.

METHODS

A survey of radiographers with mammography experience in Australia was conducted using SurveyMonkey™. Respondents were asked if they could confidently identify images of devices and whether they had imaged them mammographically. A Chi-squared test of independence was used to compare the association between demographics and CIED awareness. A value of p < 0.05 was deemed statistically significant.

RESULTS

There were 220 valid responses. All CIED types had been imaged. Most respondents had imaged a pacemaker (94.5%) and implantable cardioverter-defibrillator (ICD) (85.6%), compared to the three different implantable loop recorders (ILRs) (ILR-1: 63.4%; ILR-2: 14.1%; and IRL-3: 26.9% and the emerging subcutaneous ICDs (S-ICDs) (11.9%). Most respondents felt confident identifying the pacemaker (95%) and the ICD (86.1%). Only 19.4% of respondents could confidently identify the emerging S-ICD.

CONCLUSION

A lack of awareness of new and emerging devices may impact approaches to imaging and present significant risk to patients. The lack of studies comprehensively describing devices and their mammographic appearance to support radiographers' knowledge and awareness highlights an urgent need to progress research in this area.

IMPLICATIONS FOR PRACTICE

As a part of continuing professional development, radiographers performing mammography must ensure they remain up to date with current and emerging technology, including CIEDs. This study has identified a lack of awareness of the different types of CIEDs currently being implanted and imaged, which may translate to unsafe imaging practices. There is an urgent need for further education to bridge this knowledge gap and ensure the safety of practice in imaging women with CIEDs.

FOOTLINE

Mammography: CIED Imaging.

Pacemaker in patients undergoing mammography: A limitation for breast cancer diagnosis?

INTRODUCTION

A pacemaker may affect the utility of a mammogram in several ways. The aim of this study is to summarize our institution's experience with mammograms among patients with a cardiac pacemaker, focusing on the diagnostic workup among patients with a newly diagnosed ipsilateral breast cancer.

METHODS

A retrospective search of all mammography reports between January 2011 and April 2021 was conducted for identifying cases of patients with a pacemaker. Demographic and clinical characteristics as well as mammography-derived quality parameters and findings were categorized and statistically compared.

RESULTS

The incidence of pacemaker concurrence in mammographic examination, although apparently slightly under-documented, accounted for 0.33% of cases. Population mean age was 71.7 years, and most patients (79%) had a left-sided pacemaker. The pacemaker was much more likely to be projected on the medio-lateral-oblique (96%) than on the cranio-caudal view (10%), on the axilla rather than the breast, and on the retro-pectoral rather than the pre-pectoral region (P < 0.001 for all). Compression force decreased by up to 23.0% (P < 0.001) and breast thickness increased by up to 9.5% (P < 0.001) for the ipsilateral vs. the contralateral side. Among 11 patients with newly diagnosed ipsilateral breast cancer, the pacemaker partially projected on the tumour region in two cases, and significantly obscured the tumour in another two.

CONCLUSION

Although rare, the coexistence of a pacemaker in patients undergoing mammography is associated with reduced image quality due to suboptimal breast visualization and reduced compression, and as a result, this may eventually lead to decreased diagnostic efficacy.

The Post-Operative Mammographic Appearance of Lymphovenous Bypass and Vascularized Lymph Node Transfer

The postoperative mammographic imaging appearance related to lymphovenous bypass and vascularized lymph node transfer has not been described. It is important for breast imagers to become familiar with the expected appearance of surgical changes that can be seen in the follow up imaging of breast cancer survivors in order to create accurate reports and adjust imaging protocols to improve imaging quality and lessen patient discomfort as needed.

The mammographic appearance of the BioMonitor implantable loop recorder

The imaging appearance of implantable loop recorders (ILR's) have been described in literature (Steinberger and Margolies, 2017; Mayo and Leung, 2017; Tsau and Berger, 2004)^1-3; however, the mammographic appearance of the BioMonitor ILR produced by BIOTRONIK has not been described. It is important for radiologists interpreting breast imaging to become familiar with the appearance of different implantable cardiac devices on mammograms in order to create accurate reports and adjust imaging protocols to improve imaging quality and lessen patient discomfort as needed.