By: Shaun Kim
What is SPECT Scan?
SPECT Scan is short for single-photon emission computerized tomography scan. It uses a radioactive substance along with a special camera to create 3d images. The primary purpose of this scan is for a doctor to analyze how the patient’s organs are functioning by highlighting blood flow. Blood flow is an indicator of the organs’ activity level (Mayo Clinic, 2022).
What can SPECT Scan diagnose?
- Brain
- Traumatic brain injury
- Alzheimer’s disease
- Epilepsy
- Seizures
- Stroke
- Other issues impacting blood flow in the brain
- Heart
- Pinpoint pathological areas in the heart by capturing blood flow
- Clogged Arteries
- Inefficient Pumping of blood
- Scar tissue from a previous heart attack
- Determine the need for bypass surgery
- Bone
- Bone cancer
- Stress fractures
- Bone infections
(Jaszczak, 2020)
SPECT Scan and Epilepsy
SPECT scan is specifically used as a presurgical evaluation for patients with refractory epilepsy to accurately localize the ictal foci. Ictal foci refer to the region of the brain that is causing the seizure as ictal means during a seizure (Fisher et al., 2014) Accurate localization of ictal foci is important for patients suffering from refractory epilepsy, because patients who have reached this stage of epilepsy can no longer rely on medicine to control their seizures (John Hopkins Medicine, 2019). Thus, the only option available to them is either surgery or electrical stimulation.
Surgery for refractory epilepsy was limited to a few patients because the previous method to localize the ictal foci was called scalp EEG. Scalp EEG used electrodes to detect signals from the brain which was evaluated by doctors to localize the structure causing the seizure. However, it had difficulty differentiating seizure origins in deeper brain areas unreachable by electrodes. More invasive measures were required to detect signals from deeper structures, and it often gave subpar results (Ebersole, Pacia, 1996).
This is where SPECT scan comes into play as it’s a noninvasive neuroimaging method with a unique capability in detecting blood flow functional changes during seizures. This gives accurate localization of structures causing the seizure, making surgery a viable option for patients suffering from refractory epilepsy (Kim, Mountz, 2011).
Process for SPECT Scan
There isn’t much to prepare for the SPECT scan, but it may take just a few hours to several days for the scan to be completed. This is because SPECT scan requires the scan to take place during the onset of a seizure. The patient will have to wait after a radioactive injection (tracer) through an intravenous infusion in the arm until the onset of a seizure.
Some key things to note before the scan is
- Leave metallic jewelry at home
- Inform the technologist if you’re pregnant or breast-feeding
- Bring a list of all the medications and supplements you take
The scan will take place in the SPECT machine, a large circular device containing a camera that detects the radioactive tracer in the patient’s body. During the scan, the patient will lie on a table while the machine is rotating around the patient much like an MRI. The length of the scan is dependent on the reason for the patient’s procedure.
After the test, the radioactive tracer will leave the patient’s body through urine within a few hours. The patient will be asked to drink more fluid to help flush the tracer out. Over the next few days, the tracer that has not been flushed out will be broken down naturally.
(Mayo Clinic, 2022)
Risks of SPECT Scan
SPECT scans are generally very safe and do not trigger harmful side effects.
Minor bleeding, pain, or swelling at the injection site of the radioactive tracer may occur which should diminish within a day or two. There are some rare cases of patients having an allergic reaction to the radioactive dye which may result in the doctor suggesting that the patient does not undergo a SPECT scan. The patient will still be able to be diagnosed by alternative methods such as MRI (Netmeds.com, 2022).
Conclusion
SPECT scans are a safe, non-invasive method to accurately localize the area causing seizures to patients suffering from refractory epilepsy. It can provide crucial information for a successful surgery and poses little to no risk to the patient. Its unique capacity to create a 3D depiction of the patient’s blood flow in pathological areas gives it extensive uses outside of just epilepsy as well.
Reference
Ebersole, J. S., & Pacia, S. V. (1996). Localization of temporal lobe foci by ictal EEG patterns. Epilepsia, 37(4), 386–399. https://doi.org/10.1111/j.1528-1157.1996.tb00577.x
Fisher, R. S., Scharfman, H. E., & deCurtis, M. (2014). How can we identify ictal and interictal abnormal activity? Issues in Clinical Epileptology: A View from the Bench, 3–23. https://doi.org/10.1007/978-94-017-8914-1_1
Jaszczak, M. (2020, June 9). What can spect diagnose? Data Spectrum. Retrieved February 5, 2023, from https://www.spect.com/blog/what-can-spect-diagnose/
Kim, S., & Mountz, J. M. (2011). SPECT imaging of epilepsy: An overview and comparison with F-18 FDG Pet. International Journal of Molecular Imaging, 2011, 1–9. https://doi.org/10.1155/2011/813028
Mayo Foundation for Medical Education and Research. (2022, July 27). SPECT scan. Mayo Clinic. Retrieved February 5, 2023, from https://www.mayoclinic.org/tests-procedures/spect-scan/about/pac-20384925#:~:text=A%20single%2Dphoton%20emission%20computerized,camera%20to%20create%203D%20pictures.
Mayo Foundation for Medical Education and Research. (2022, July 27). SPECT scan. Mayo Clinic. Retrieved February 5, 2023, from https://www.mayoclinic.org/tests-procedures/spect-scan/about/pac-20384925#:~:text=You%20may%20be%20asked%20to,injection%20and%20your%20SPECT%20scan.
Refractory epilepsy. Refractory Epilepsy | Johns Hopkins Medicine. (2019, November 19). Retrieved February 5, 2023, from https://www.hopkinsmedicine.org/health/conditions-and-diseases/epilepsy/refractory-epilepsy#:~:text=The%20usual%20electrical%20activity%20in,all%2C%20to%20control%20the%20seizures.
SPECT scan: Procedure, risks and results. Netmeds. (n.d.). Retrieved February 5, 2023, from https://www.netmeds.com/health-library/post/spect-scan-procedure-risks-and-results
