Which imaging techniques does not collect information about brain functioning

There are various imaging techniques in collecting information about the brain and its adjacent structures. To enumerate, there are the cranial ultrasound (for children with cranial sutures that are not closed yet), cranial CT-scan, cranial MRI, brain PET scan, and cranial functional MRI. Only the brain PET scan and cranial functional MRI can collect information about the brain function by detecting fluorodeoxyglucose (FDG) in the brain as this lights up in functional areas of the brain in PET scan; and by detecting brain activity through changes in blood flow in cranial functional MRI. 

While it is not an imaging technique, electroencephalogram or EEG can detect brain function.

I’d say a : water molecules