An automated injection system (with patient selection) for SPECT imaging in seizure localization

Purpose: Ictal single-photon-emission computed tomography (SPECT) provides lateralization but has technical limitations: (a) a 'truly ictal' injection must be shortly after seizure onset; (b) therefore, a seizure of brief duration may be missed; (c) more than one patient may need testing at any given time; (d) a trained health professional must stay next to each patient to inject; and (e) because the radionuclide is placed in the syringe in advance of the injection, decay of the radioactive element could result in less than optimal uptake, if the same volume of material were to be used regardless of the time after ligand preparation. Methods: We developed an automated method of ligand injection that shortens time and increases efficiency of ictal SPECT ligand injection. By using an experimental setup, we compared manual injection times with times using an auto- mated injection system. We determined relative costs and efficiency in work hours for the manual and automated methods. Results: Injection times were 8-14 s with automated versus 19-26 s with manual injection. Readjusting volume for 'ligand' decay was simple and accurate with the automated system. Injection times for clinical SPECT studies in three patients were 13, 13, and 12 s, respectively. The price of one pump equals 120 work hours of a nurse or 24 ictal injection attempts. Much of the nurse's time is 'wasted' because no seizure occurs. Conclusions: The method can be more efficient of staff, shorten injection time, and facilitate obtaining 'truly ictal' injections. It allows more cost-effective use of personnel.