Role of Strain Elastography in the Evaluation of Borderline Axillary Lymph Nodes in Breast Cancer Patients

Abstract

Background: Detection of malignant infiltration in axillary lymph node remains a significant
predictive factor in breast cancer with a significant impact on prognosis and staging. Elastography
new ultrasound method developed that measures the stiffness of tissue can diagnose early
malignant change in the cortex of lymph node and can help to decrease the use of invasive
procedures.
Aim of the study: Analyzing strain elastography findings in borderline axillary lymph nodes
in breast cancer patients.
Patients and method: This is a prospective cohort study conducted in the Breast Center/Shar
Hospital / Sulaymaniyah City/ Iraq, in a period of one year between October 2022 and October
2023. Forty-two patients 2 males and 40 females with newly diagnosed breast cancer were
included in the study, we examined the patients with conventional ultrasound and elastography
with a 7.5-12MHz superficial linear transducer using Samsung HS60 and Samsung V7 ultrasound
machines. After determining whether borderline axillary LNs were present ultrasound
elastography was performed for the borderline lymph node, and each case was properly described
and reported. After gray-scale ultrasonography, Elastography (real-time Elastography) was
conducted. In our study, we used a 5-point scoring system. To determine the strain ratio, a circular
region of interest (ROI) was positioned in the axillary fat, and the second ROI was set at the same
level and of the same size over the stiffest part of the lymph node being studied. The final reference
was the histopathological result of the core needle biopsy of the examined lymph node.
Results: A total of 42 patients were studied, the age range was between 33- 77 years old. 54.8%
(n=23) of our patients were negative for malignant cells, whereas 45.2% (n=19) were positive. The
strain ratio (SR) of the negative results for malignant cells (1.8 ± 0.9) was much lower than the
positive results (4.7 ± 1.4). Two-thirds (65.2%, n=15) of the negative results had SR less than 2.1
and the rest 34.8% (n=8) were ≥ 2.1. On the contrary, the positive results, (94.7%, n=18) were ≥
2.1, and only 5.3% (n=1) was below 2.1, with a statistically highly significant difference
(P<0.001). Regarding elasticity score, more than half (56.5%, n=13) of the patients with negative
results for malignant cells have score 2, about one-third (34.8%, n=8) have score 3, and 4.3% (n=1)
have score 4, also, score 1 was 4.3% (n=1). Paradoxically, the majority of the positives (52.6%,
n=10) have score 3, followed by score 4 (21.1%, n=4) then score 2 (15.8%, n=3) then score 5
(10.5%, n=2). With a significant difference (P=0.027).
Conclusion: The strain ratio and elasticity score of malignant borderline axillary lymph node is
much higher than that of benign lymph node, making this new ultrasound method superior to B
mode in the detection of early malignant infiltration to the cortex of axillary lymph node. These
two non-invasive methods (B-mode ultrasound and elastography) can be used together to increase
diagnostic accuracy. 65.2%, (n=15) of the negative results had SR less than 2.1 whereas 94.7%
(n=18) of malignant cases had a strain ratio ≥ 2.1. Regarding elasticity score 60% of benign cases
had scores 2 and 1, whereas 84% of malignant cases had scores 3,4, and 5.