Objectives <p>Systemic lupus erythematosus (SLE) is associated with vasculitis of varying severity. Conventional ultrasonography faces challenges in accurately assessing this condition, whereas the development of photoacoustic (PA) imaging offers a promising approach. This study aims to evaluate the clinical utility of PA imaging in assessing vasculitis changes in patients with SLE.</p> Methods <p>A total of 102 patients diagnosed with SLE were enrolled as the case group and subdivided into two subgroups: the non-active group and the active group, according to the systemic lupus erythematosus disease activity index 2000 (SLEDAI-2000) scoring criteria. 35 healthy volunteers were recruited as the control group. PA was performed to measure the oxygen saturation of the bilateral radial arterial wall and perivascular tissues.</p> Results <p>(1) Active SLE patients showed significantly elevated oxygen saturation (SO₂) levels of radial artery wall and perivascular tissues compared to nonactive patients and healthy controls (<i>p</i> &lt; 0.05). (2) Correlation analysis showed that the average oxygen saturation of bilateral radial artery wall and perivascular tissues was positively correlated with SLEDAI-2000 (<i>r</i> = 0.571) and negatively correlated with complement 3 (C3), complement 4 (C4), and serum albumin (<i>r</i>=-0.453, -0.493, -0.313, respectively). Univariate and multivariate regression analysis showed that SLEDAI-2000 was independently associated with SO₂. (3) The SO₂ was associated with disease activity status in SLE patients, with an area under the curve (AUC) of 79.6%.</p> Conclusions <p>Photoacoustic imaging effectively detects the oxygen saturation changes in the radial arterial wall and perivascular tissues in patients with SLE. These findings suggest its potential as a tool for evaluating SLE-related vasculitis.</p>