Receptor imaging and therapeutic response are different kinds of evidence.
Twelve medication-free participants with PTSD and fifteen controls underwent PET imaging with carbon-11 flumazenil. Regional binding potential differed between groups, and some regional measures correlated with symptom severity. The findings differed in pattern from parts of the earlier imaging literature discussed by the authors.
The sample was small and cross-sectional. Binding potential is influenced by tracer and receptor-system properties; it is not a direct measurement of how much anxiety a benzodiazepine would relieve. Correlation does not establish that the receptor difference caused PTSD.
For an imaging opinion, distinguish a radiotracer research dose from therapeutic reversal or sedation. Do not infer benzodiazepine exposure from a study of medication-free patients, or use a regional group difference as an individual diagnostic test without separate validation.
Source: Publication PMC6172250. The case-review applications above are interpretive analysis.
Related reading: Flumazenil PET in Fragile X Syndrome Measures Binding Availability.