Applicability of B-mode ultrasound, Doppler, and ARFI elastography in the diagnosis and therapeutic monitoring of multicentric lymphoma in dogs

High-grade multicentric B-cell lymphoma is one of the most common and clinically aggressive forms of canine lymphoma. Although most dogs initially respond to polychemotherapy, relapse is common and is thought to result from persistence of minimal residual disease. Current response evaluation methods based on caliper measurements may fail to detect early relapse. This prospective study aimed to evaluate the clinical utility of B-mode, Doppler ultrasonography, and Acoustic Radiation Force Impulse (ARFI) elastography for the diagnosis and therapeutic monitoring of multicentric B-cell lymphoma in dogs and to investigate their association with histopathological, immunohistochemical (IHC), and clinical findings. Twenty dogs with lymphoma and sixteen healthy control dogs were prospectively evaluated. Lymph node morphology, echotexture, vascularization, and shear-wave velocity (SWV) were analyzed by ultrasonography at different time points before and during CHOP chemotherapy in dogs with lymphoma. At diagnosis, lymph nodes from dogs with lymphoma were rounder, more heterogeneous, and stiffer than those from healthy controls ( p < 0.001). During treatment, SWV significantly decreased in dogs achieving a complete response ( p = 0.033) and increased again at relapse. An SWV cut-off value > 3.11 m/s measured at diagnosis predicted shorter survival (HR = 6.27; p = 0.006). Collagen analysis demonstrated a predominance of immature type III collagen and a lower proportion of mature type I collagen in the lymphoma group ( p = 0.021). These findings suggest that ARFI elastography and Doppler ultrasonography may represent valuable non-invasive imaging tools for monitoring therapeutic response and prognosis in canine multicentric lymphoma. Increased lymph node stiffness was associated with poorer outcomes and may indicate disease relapse.