Non-Hodgkin lymphoma (NHL) is clinically heterogeneous and lacks practical tools for repeated, noninvasive monitoring of response. We performed longitudinal photoacoustic imaging (PAI) at five time points in NHL xenografts to quantify Hb, HbO2, HbT, and mSO2, with endpoint histologic and serum validation. Untreated tumors exhibited a natural progression characterized by a progressive decline in mSO2. While Cyclophosphamide (CTX) slowed growth, it induced earlier alterations in oxygenation: mSO2 was higher in the CTX group on Day 7 (P < 0.05), before tumor volume divergence became evident, whereas Hb and HbT were lower at the mid-treatment stage. Thereafter, mSO2 declined more steeply in the CTX group from Day 7 to Day 13, despite similar absolute mSO2 values at the endpoint. Endpoint readouts showed higher HIF-1α and MVD, and lower VMI, indicating immature vasculature. These data support the use of longitudinal PAI as an additional biomarker to evaluate and optimize therapy in NHL.
Shi et al. (Fri,) studied this question.