Sonoelastography as an adjunct imaging modality to PET-CT in characterization of superficial lymph nodes in pediatric lymphoma

Abstract Background and objectives Lymphomas constitute the third most prevalent childhood malignancy globally, accounting for 10–15% of all pediatric cancer. FDG PET/CT has become the gold-standard imaging modality for lymphoma management due to its superior diagnostic accuracy. Ultrasound elastography represents an emerging noninvasive radiation-free imaging modality that quantitatively assesses tissue stiffness and elastic properties. The main goal of the current study is to evaluate the diagnostic performance of ultrasound elastography in assessing the stiffness of superficial lymph nodes in pediatric lymphoma patients, and to determine its correlation with PET-CT (SUVmax) findings as a radiation-free adjunct imaging modality. Results This is a prospective cross-sectional study which included 45 pediatric patients with pathologically proven not treated lymphoma, with a mean age of the patients of 10.6 years ± 3.83 (SD). Histopathology was the reference standard for diagnosis at patient level, and PET-CT served as the imaging reference for nodal metabolic activity. Three different groups of superficial lymph (cervical, axillary, and inguinal) nodes were assessed in each patient using both PET-CT and elastography, resulting in a total of 135 lymph node group. B-mode ultrasound provides standard evaluation of lymph node as initial step. For each patient, the most representative lymph node from each group was selected for correlation between PET-CT and ultrasound elastography. Node matching was performed based on anatomical location (cervical nodal level or nodal station), nodal size, depth from the skin surface, and relationship to adjacent vascular and muscular landmarks. PET/CT and ultrasound elastography data were gathered and were compared. PET-CT result revealed eighty-one lymph node groups (60%) demonstrated standardized uptake value maximum (SUVmax) measurements exceeding reference SUVmax values, while 54 nodal groups (40%) maintained SUVmax values below these established diagnostic values. A statistically significant correlation ( P ≤ 0.001) was identified between shear wave elastography (SWE) patterns and the pathological status of lymph nodes, with malignant lymph nodes predominantly demonstrating type III elastographic patterns. Additionally, significant associations were found between the diagnosis of lymph node nature and the mean shear wave stiffness, mean shear wave velocity, and mean strain ratio, all of which exhibited higher values in the malignant group ( P ≤ 0.001). Furthermore, a statistically significant relationship was observed between the elastography strain score and the diagnostic classification of lymph nodes, as a higher proportion of scores 2 and 3 were present in malignant groups ( P ≤ 0.001). Conclusions Elastography is a promising, noninvasive, non-radiating method for differentiating between benign and malignant superficial lymph nodes in pediatric lymphoma. UE provides reliable quantitative and qualitative stiffness parameters that strongly correlate with PET/CT-defined malignant lymph nodes in pediatric lymphoma. UE represents a valuable complementary, radiation-free imaging tool for evaluating superficial lymphadenopathy rather than a standalone alternative to PET/CT.