time: (d) a trained health professional must stay next to each patient to inject; and (e) ... compared manual injection times with times using an auto- ... Perfusion may differ between me- ..... We previously reported that the degree of local hyper-.
Epilepsia, 39(12):1350-1356, 1998 Lippincott Williams & Wilkins, Philadelphia
0 International League Against Epilepsy
An Automated Injection System (with Patient Selection) for SPECT Imaging in Seizure Localization “Jehuda P. Sepkuty, *?Ronald P. Lesser, SCahid A. Civelek, “Barbara Cysyk, *Robert Webber, and $Roy Shipley Departments of *Neurology, fNeurosurgery, $Nuclear Medicine Division, and §Clinical Engineering, Johns Hopkins University, Johns Hopkins Hospital, Baltimore, Maryland, U.S.A.
Summary: 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. Key Words: SPECT-Automated-Injection system-LigandIctal.
Single-photon-emission computed tomography (SPECT) is a powerful technique that provides an opportunity to assess cerebral perfusion during both ictal and interictal states. Although structural imaging is of increasing value, some patients have complex seizure problems, and routine imaging of their structural lesions may not be sufficient to indicate the precise region of seizure onset. Since SPECT was introduced for the presurgical evaluation of medically intractable epilepsy, there have been significant technical improvements in the hardware and software, in terms of spatial resolution, and the ligands are more readily available, less costly, and have better imaging quality. Clinical experience has accumulated as well, using SPECT for both temporal and extratemporal seizure foci (1-5). Despite these advances, the need to inject very soon after seizure onset to lateralize and localize the seizure focus more accurately, plus the need to have someone present to inject the tracer, limit the use of this technique (4,6,7,12).
1. The injection should occur at or shortly after seizure onset (6,8-11,13-17), because cerebral hyperperfusion at seizure onset more accurately reflects the area where the seizure originates. Cerebral perfusion during a later stage is more likely to reflect seizure spread. Perfusion may differ between mesial temporal lobe epilepsy (MTLE) and extratemporal epilepsy, as seizures that originate in a part of the MTLE epileptogenic network tend to remain confined to the network for extended periods, before propagating elsewhere (13,18). In our experience, the majority of clinical SPECT injections are performed in patients suspected to have extratemporal epilepsy and other difficult cases in whom injection latency may be of greater importance (1 1). 2. Therefore, seizures of very brief duration (
