Striatal DAT-SPECT texture beyond mean binding in major depressive disorder

Dopaminergic dysfunction has been implicated in major depressive disorder (MDD), but dopamine transporter (DAT) imaging studies using conventional mean binding have yielded inconsistent findings. One possible contributor is that mean binding reduces striatal uptake to a single value, so spatially heterogeneous alterations in DAT uptake may be attenuated or missed. Radiomic texture analysis may capture such spatial patterning, but features are numerous and difficult to interpret.

We retrospectively examined whether a low-dimensional texture signature from striatal DAT-SPECT (¹²³I-ioflupane) provides incremental information beyond mean binding. In 223 patients, bilateral striatal mean binding and texture metrics were quantified. Features were summarized into two domains: entropy/complexity and scale/run-length. Ordinal regression models adjusted for age, sex, and medication status tested associations with depressive severity and, in 151 depressed patients with evaluable treatment-course data, with a proxy for required treatment intensity (monotherapy/augmentation therapy, or electroconvulsive therapy [ECT]).

In nested models, mean binding did not improve fit for either outcome, whereas adding the two texture domains improved fit for severity (p = 0.024) and treatment intensity (p = 0.0048). Higher texture scores were associated with higher probabilities of severe depression and of requiring ECT, and the treatment intensity association remained after adjustment for concurrent symptom severity. In a remission-pair subset (N = 40), texture score changes showed only limited evidence of a decrease and were not related to symptom improvement.

A two-domain texture summary showed incremental associations beyond mean binding with depressive severity and a proxy for required treatment intensity in MDD.