Real-time ultrasound elastography in 180 axillary lymph nodes: elasticity distribution in healthy lymph nodes and prediction of breast cancer metastases

Abstract

BackgroundTo determine the general appearance of normal axillary lymph nodes (LNs) in real-time tissue sonoelastography and to explore the method′s potential value in the prediction of LN metastases.MethodsAxillary LNs in healthy probands (n=165) and metastatic LNs in breast cancer patients (n=15) were examined with palpation, B-mode ultrasound, Doppler and sonoelastography (assessment of the elasticity of the cortex and the medulla). The elasticity distributions were compared and sensitivity (SE) and specificity (SP) were calculated. In an exploratory analysis, positive and negative predictive values (PPV, NPV) were calculated based upon the estimated prevalence of LN metastases in different risk groups.ResultsIn the elastogram, the LN cortex was significantly harder than the medulla in both healthy (p=0.004) and metastatic LNs (p=0.005). Comparing healthy and metastatic LNs, there was no difference in the elasticity distribution of the medulla (p=0.281), but we found a significantly harder cortex in metastatic LNs (p=0.006). The SE of clinical examination, B-mode ultrasound, Doppler ultrasound and sonoelastography was revealed to be 13.3%, 40.0%, 14.3% and 60.0%, respectively, and SP was 88.4%, 96.8%, 95.6% and 79.6%, respectively. The highest SE was achieved by the disjunctive combination of B-mode and elastographic features (cortex >3mm in B-mode or blue cortex in the elastogram, SE=73.3%). The highest SP was achieved by the conjunctive combination of B-mode ultrasound and elastography (cortex >3mm in B-mode and blue cortex in the elastogram, SP=99.3%).ConclusionsSonoelastography is a feasible method to visualize the elasticity distribution of LNs. Moreover, sonoelastography is capable of detecting elasticity differences between the cortex and medulla, and between metastatic and healthy LNs. Therefore, sonoelastography yields additional information about axillary LN status and can improve the PPV, although this method is still experimental.

Sonography and sonoelastography in the detection of malignancy in superficial lymph nodes of dogs

“…In the benign nodes, a high frequency of score 1 (soft) was found, whereas in malignant nodes a high frequency of score 4 (stiff) was found, similar to results described in a previous study that evaluated a population comprised mostly of deep canine and feline lymph nodes . Although variations may occur, particularly in lymphomatous nodes with necrotic areas, malignant nodes of human patients showed >45% of their total area with stiff elasticity because of infiltration by tumor . An important proportion of lymph nodes in both groups had overlapping elastographic scores, as previously described, limiting the use of SOE individually for the detection of malignancy.…”

Role of Elastography in Axillary Examination of Patients With Breast Cancer

“…Our study demonstrated that elastography may provide additional information for the diagnosis of axillary lymph nodes, similar to previous research. [28][29][30] However, Park et al 8 indicated that strain elastography of abnormal axillary lymph nodes in patients with breast cancer did not improve diagnostic accuracy compared with conventional US alone. Different combinations of methods Figure 4.…”

Differentiating benign from malignant superficial lymph nodes with sonoelastography

“…Blue areas, depicting rigid, hard tissue, occupy more than 45% of the lymph node area [7]. Red, yellow and green are not encountered in malignant deposit areas, where stiff tissue is depicted only in turquoise and blue [17]. The cortex is stiffer than the medulla or the node is uniformly hard (fig 2).…”

“…Other authors [17,18] suggest that the lymph node should occupy no more than 30% of the ROI and neighboring tissue at least 70%. It is, however, important to avoid the presence of bone or blood vessels in the scan area, as it may alter the overall image interpretation.…”

“…Benign nodes are mostly displayed in colors of yellow, green and turquoise, color red being never encountered and blue of sparse and inconstant occurrence. On the color scale, nodal cortex appears harder than the medulla [17] (fig 1).…”