Breast cancer is known as the most frequently diagnosed malignancy among women globally, affecting 2.3 million patients in 2024.1 Proper care and the use of optimal methods to determine the need for invasive interventions in patients are some of the most important factors in improving outcomes in these patients. The use of biopsy for detecting lymph node metastasis in patients with primary breast tumors plays an important role in tumor staging, prognosis, and overall survival outcomes.2

Historically, assessing axillary lymph node status required patients to undergo complete axillary lymph node dissection (ALND) for both diagnostic and therapeutic purposes. In the last 15 years, sentinel lymph node biopsy (SLNB) has become the primary alternative to ALND for the classification of breast cancer patients with a negative clinical node, and it is suggested that if there is a positive finding in the patients' SLNB, in the next step, they should go for a complete ALND.3

Current findings from the ACOSOG Z0011 clinical trial indicate that the indication for ALND is no longer based only on distinguishing between negative (N0) and positive (<N1) metastasis. Instead, the decision now differentiates between the absence or presence of nonsignificant metastasis (N0–N1 and 0–3 positive nodes) vs significant lymph node metastasis (≥N2 and ≥4 positive nodes). In addition, those who have tumors with T1 and T2 stages can also skip ALND.4

Although SLNB as the first stage is a less invasive method than ALND, it is associated with complications such as lymphedema, paresthesia, and possibly permanent impairment of arm muscle movement.5 As a result, in recent years, noninvasive methods such as ultrasonography and PET-CT have been suggested to evaluate the axilla in the first stage.5 Compared with other imaging methods for lymph node evaluation, MRI offers benefits including the absence of ionizing radiation and superior interobserver and intraobserver reliability.6,7

Performing breast MRI with contrast injection and taking several hundred images can take between 30 and 40 minutes. The time required to generate a report by the radiologist should also be considered. Abbreviated MRI (AB-MRI) is a shortened version of the standard full-diagnostic protocol in breast MRI (FD-MRI), which was introduced as a diagnostic and screening tool. Compared with FD-MRI, AB-MRI requires less scanning time, is associated with reduced costs, and therefore is more practical, especially in high-patient-volume centers and in centers with limited MR slots.6,8 Contrast enhancement in lymph nodes, which occurs regardless of malignancy, complicates the diagnostic challenge of distinguishing metastatic from nonmetastatic disease. Moreover, the intrinsic challenge of differentiating lymph nodes from adjacent adipose tissue requires the implementation of a specialized pulse sequence. A complete staging approach, incorporating precontrast imaging, is vital for precise evaluation.4 Limited studies have focused on the use and effectiveness of AB-MRI in the investigation of axillary lymph node metastasis, comparing it with the standard FD-MRI protocol, and so far, most of them have focused on the use of this method in the diagnosis of breast cancer. This study aims to compare the accuracy of AB-MRI with and without contrast and FD-MRI in the diagnosis and staging of axillary lymph node metastasis in breast cancer.

Preoperative MRI was evaluated against surgical pathology in a cohort of 88 women with breast cancer. The mean age of patients was 46.5 (9.4) years and the mean size of lymph nodes was 30.5 (19.2) mm. The patient’s demographic and tumor characteristics are presented in Table 1.

All 88 patients underwent precontrast T1-weighted coronal sequence breast MRI. Axillary lymph node (ALN) involvement was detected in 50 patients in noncontrast AB-MRI. The distribution of involvement by anatomical level was as follows: 38 patients (76% of the patients with ALN) were observed to have only level I involvement, 4 patients (8% of the patients with ALN) to have only level II involvement, 4 patients (8% of the patients with ALN) to have both levels I and II involvement, and 4 patients (8% of the total) to have levels I, II, and III involvement (Figure 1A, Figure 2A). In the remaining 38 patients, no ALN involvement was detected on noncontrast AB-MRI. Pathology results were available for these patients. Of the 50 patients with ALN involvement on MRI, 45 cases were histopathologically positive. Of the 38 patients without ALN involvement on MRI, 30 were proven negative in histopathology.

Contrast-enhanced AB-MRI reported 49 cases of positive lymph involvement and 39 cases of negative involvement among 88 patients. Among 49 patients, 37 cases (75.4%) had level 1 lymph node involvement, 4 cases (8.2%) with level 2 lymph node, 4 patients (8.2%) with level 1 and 2 lymph nodes, and 4 cases (8.2%) had involvement of all 3 levels (Figure 1B, Figure 2B). Also, 43 cases out of the 49 patients with ALN involvement on MRI were proven positive in pathology. Of the 39 patients without ALN involvement on MRI, 29 had a negative histopathology. Among the 88 patients who underwent a FD-MRI, 53 cases showed axillary lymph node involvement, while 35 cases did not. Out of the 53 patients, 40 cases (75.6%) had level 1 lymph node involvement, 4 cases (7.5%) had level 2 lymph node involvement, 5 patients (9.4%) had involvement in both levels 1 and 2, and 4 cases (7.5%) had involvement across all 3 levels (Figure 1C, Figure 2C). Histopathology results were positive in 47 of the 53 patients with lymph node involvement and negative in 29 of the 35 patients without it. Sensitivity, specificity, PLR, NLR, and accuracy of the 3 protocols evaluated in this study for detection of lymph node involvement are summarized in Table 2, Table 3, Table 4, and Table 5. McNemar test showed no statistically significant difference among the 3 protocols in the detection of axillary lymph node involvement; however, the study was not powered for equivalence (all P > 0.05) (Figure 1D, Figure 2D). Moreover, the high unweighted Cohen κ confirmed high agreement among the various MRI protocols for the detection of lymph node involvement. The comparison between the noncontrast AB-MRI and the contrast-enhanced AB-MRI protocols yielded a κ value of 0.931 (95% CI, 0.86–1.00), indicating very good agreement. Similarly, the contrast-enhanced AB-MRI showed substantial agreement with the FD-MRI, with a κ of 0.907 (95% CI, 0.82–1.00). The agreement between the noncontrast T1-weighted and the FD-MRI was also very good, with a κ value of 0.930 (95% CI, 0.85–1.00). All κ values were statistically significant, with P < 0.001.

Implementing AB-MRI offers substantial workflow benefits through reduced acquisition time (3 to 10 minutes vs 30+ minutes for full-diagnostic MRI), enabling higher throughput in busy centers and addressing limited MRI slots. Cost savings from shorter scans and simplified reading (often <3 minutes) make AB-MRI feasible for broader screening, particularly in high-volume or resource-limited settings, while avoiding gadolinium in contraindicated patients via unenhanced protocols. This study highlights the noninferior performance of a T1-weighted pulse sequence, acquired using the system’s built-in body coil, into the standard preoperative breast MRI protocol in comparison to full-protocol MRI. This modification significantly improves the discovery of axillary lymph node involvement, demonstrating a high positive predictive value. Historically, prior to the advent of SLNB, all patients diagnosed with invasive breast cancer underwent complete ALND for both diagnostic and therapeutic goals.13 To mitigate the considerable morbidity associated with ALND, SLNB was introduced as a less invasive alternative.14 However, before the ACOSOG Z0011 study, patients with positive SLNB findings were still required to undergo complete ALND. The results of the aforementioned study led to a paradigm shift, allowing women with invasive breast tumors up to 5 cm in size, no clinically palpable axillary or parasternal lymph nodes, and 1 to 2 positive SLNB nodes to avoid axilla dissection.15

The final confirmation of lymph node metastasis is performed by invasive methods, and finding methods to identify lymph node metastasis preoperatively and with less invasiveness is one of the current goals. Ultrasound remains the primary modality for this purpose owing to its accessibility, real-time assessment, and capability for image-guided sampling. Nonetheless, its performance may be limited by operator dependency, restricted coverage, and reduced sensitivity for small or deep-seated metastases.16,17 In this context, our study investigated the potential of an abbreviated noncontrast MRI protocol as a complementary tool in specific clinical scenarios. This approach would be particularly relevant if noncontrast techniques like diffusion-weighted imaging advance sufficiently to become reliable standalone methods for screening or staging.

Because of its limited ability to provide complete visualization of the axilla region, MRI currently plays a minor role in imaging this region. Although protocols specific to the axilla region have increased sensitivity, specificity, positive and negative predictive value, these protocols require more time and are currently not very useful in the clinic.5 The acquisition of a standard full MRI protocol, which includes multiple sequences, is traditionally a lengthier process, while the abbreviated protocol is performed by omitting certain sequences and reducing the time required for imaging.18 Many studies have demonstrated the potential of abbreviated MRI in the diagnosis and characterization of a variety of cancers, such as prostate, breast, cervix, and hepatocellular carcinoma.19-22 Nevertheless, the abbreviated protocol's diagnostic accuracy for the detection of axillary lymph node invasion in breast cancer has not yet been fully assessed in the literature. While MRI showed exceptional performance in detecting and characterizing primary breast cancer using different established scoring systems23, assessing axillary lymph nodes remains a challenge. This is mainly because all lymph nodes, regardless of metastatic involvement, display contrast enhancement after the administration of contrast material. Additionally, since the enhancement pattern of lymph nodes may resemble that of the surrounding fat tissue, a pulse sequence for lymph node staging is acquired prior to contrast agent injection to improve diagnostic accuracy.5 The coronal plane is particularly beneficial for visualizing parasternal, infraclavicular, and supraclavicular lymph nodes, offering a more comprehensive anatomical assessment while requiring fewer imaging sections compared to axial imaging.4

Our study showed that the noncontrast T1 sequence has the same performance as FD-MRI, with no significant difference in sensitivity and specificity. This similar performance was also supported by our interprotocol agreement analysis, which showed that all 3 protocols can be used interchangeably as indicated by consistent “very good” pairwise κ values. With its high positive and negative likelihood ratios for detecting axillary lymph node involvement, noncontrast AB-MRI shows strong potential for integration into routine clinical practice. An abbreviated, noncontrast MRI methodology provides a more cost-effective and safer method for assessing axillary lymph node involvement. This approach markedly diminishes patient exposure to the potential concerns of contrast agents, including nephrogenic systemic fibrosis, gadolinium tissue deposition, allergic reactions, and pregnancy-related concerns. Refraining from contrast administration is particularly advantageous for patients with renal insufficiency or those requiring many imaging procedures, since it alleviates the burden of contrast exposure while maintaining diagnostic efficacy. Abbreviated MRI could also enhance access to MRI in low-resource environments, where contrast agents may be few or inaccessible. It would also decrease scan duration and total examination expenses.20 Nonetheless, contrast-enhanced MRI remains indispensable for comprehensive evaluation and accurate staging of breast disease, as the abbreviated noncontrast protocol cannot delineate the full extent of tumor involvement. Accordingly, this protocol should be regarded as a complementary adjunct applicable in selected clinical scenarios rather than a replacement for standard contrast-enhanced imaging in complete disease assessment.

In the study by Kadioglu et al., 3 different types of abbreviated protocol (AP) were extracted from the full MRI protocol. In AP1, T2-weighted and diffusion-weighted axial images were acquired, whereas in AP2, axial T1-weighted fat-saturated images were attained 2 minutes after contrast administration. In AP3, both AP2 and diffusion-weighted images were analyzed. For each protocol, the lesion's location, number, size, and the presence of axillary lymphadenopathy were assessed separately. In this study, in all types of protocols, the evaluation time was shorter than the full protocol, and the best diagnostic correlation in all the investigated factors, including axillary lymphadenopathy (κ = 0.842) occurred in the AP3 protocol.24

Bode et al. investigated regional lymph nodes and reported that the addition of a short coronal T1-weighted MRI sequence was effective in identifying patients with clinically significant lymph node metastasis (≥N2), achieving a high negative predictive value (98.8%). However, the positive predictive value was relatively low (50.6%), likely because the MRI observers were only asked to report the presence or absence of lymph node metastasis, without considering the number of metastatic nodes, which defines clinically significant involvement. This limitation may have reduced the ability to correctly identify patients with ≥N2 metastasis, resulting in a lower PPV.4 Also, Pesapane et al. meta-analysis aligns with our sensitivity findings (AB-MRI 86% vs. full MRI 95%), emphasizing comparable specificity and practical advantages for dense breasts.20

Our study faced several limitations: (1) The study was retrospective, which presents inherent concerns of selection bias and unmeasured confounding. Despite the available research on this topic, further generalizable multicenter prospective investigations with large sample sizes are needed on whether abbreviated T1-weighted imaging with and without contrast can reliably stage axillary lymph nodes in breast cancer patients compared with the traditional FD-MRI. (2) The research does not assess interreader agreement among radiologists, which may indicate inconsistencies in interpretation and impact the reliability of the results and reproducibility in other settings.

Abbreviated T1-weighted MRI protocols present a promising alternative to FD-MRI, especially in time-sensitive resource-constrained settings or in a subset of patients with contraindication to contrast. Although they may not fully match the sensitivity of FD-MRI protocols for accurate detection of lymph node metastases, they provide a reliable and efficient option for detecting axillary lymph node metastasis. In clinical practice, abbreviated MRI protocols could be strategically implemented to complement traditional diagnostic pathways, reducing scan times and costs while maintaining diagnostic accuracy. Moreover, unenhanced T1-weighted MRI sequences may hold diagnostic value in lymph node assessment, especially if future developments in noncontrast MRI—primarily diffusion-weighted imaging—enable their use as standalone protocols for screening or disease extent evaluation.