Abstract
BackgroundWe assessed confidence in visualization of markers within metastatic axillary lymph nodes (LNs) on magnetic resonance imaging (MRI), which were placed post-ultrasound (US)-guided biopsy.MethodsA retrospective review was performed on 55 MRI cases between May 2015 and October 2017. Twenty-two MRIs were performed before neoadjuvant therapy, and 33 MRIs were after its initiation. There were 34/55 HydroMARK®, 10/55 Tumark®, and 11/55 other marker types. Time interval between marker placement and MRI examination was 103 ± 81 days (mean ± standard deviation). Three readers with 1–30 years of experience independently assessed four axial sequences: unenhanced fat-suppressed three-dimensional T1-weighted spoiled gradient-recalled (SPGR), first contrast-enhanced fat-suppressed SPGR, T2-weighted water-only fast spin-echo (T2-WO), and T2-weighted fat-only fast-spin-echo (T2-FO).ResultsMarkers were 5.2× more likely to be visualized on T2-WO than on unenhanced images (p = < 0.001), and 3.3× more likely to be visualized on contrast-enhanced than on unenhanced sequences (p = 0.009). HydroMARK markers demonstrated a 3× more likelihood of being visualized than Tumark (p = 0.003). Markers were 8.4× more likely to be visualized within morphologically abnormal LNs (p < 0.001). After 250 days post-placement, confidence in marker brightness of HydroMARK markers on T2-WO images was less than 50% (p < 0.001). Inter-rater agreement was excellent for T2-WO and contrast-enhanced SPGR, good for unenhanced SPGR, and poor for T2-FO images.ConclusionT2-WO and contrast-enhanced images should be used for marker identification. HydroMARK was the best visualized marker. Markers were easier to identify when placed in abnormal LNs. The visibility of HydroMARK markers was reduced with time.
Highlights
We assessed confidence in visualization of markers within metastatic axillary lymph nodes (LNs) on magnetic resonance imaging (MRI), which were placed post-ultrasound (US)-guided biopsy
In the patient who had both pre and postNAT MRI available, these were analyzed as separate studies with the readers blinded to the information that the study was from the same patient
Inter-reader agreement Inter-rater agreement was excellent for T2-weighted water-only (T2-WO) images, excellent for first contrastenhanced spoiled gradient-recalled (SPGR) images, good for unenhanced SPGR images, and poor for the T2-weighted fat-only fast-spin-echo (T2-FO) images
Summary
We assessed confidence in visualization of markers within metastatic axillary lymph nodes (LNs) on magnetic resonance imaging (MRI), which were placed post-ultrasound (US)-guided biopsy. Magnetic resonance imaging (MRI) can help in the assessment of disease extent, including axillary lymphadenopathy, and change in tumor burden post-neoadjuvant therapy (NAT) [1, 2]. In patients with breast cancer who have suspicious axillary LNs, a marker is often placed within the LN at time of biopsy. A marker is placed within suspicious or cytology/pathology proven metastatic LNs to facilitate localization and subsequent surgical removal. When these patients undergo MRI for staging or for assessment of response to NAT, the marker can be visualized on MRI. If the metastatic LN decreases in size on the post-NAT MRI, similar landmarks can be used to identify the marked metastatic LN to evaluate response to treatment
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