**Core Concept**
Functional imaging of the brain is a crucial diagnostic tool in cases of refractory epilepsy, especially when the MRI appears normal. It helps identify potential seizure foci and areas of abnormal brain activity.

**Why the Correct Answer is Right**
MDCT (Multidetector Computed Tomography) is primarily used for anatomical imaging, not functional imaging. It provides detailed structural information about the brain but does not measure brain activity or metabolism. In contrast, functional imaging techniques like SPECT, PET, and ictal SPECT with EEG can help identify areas of abnormal brain function.

**Why Each Wrong Option is Incorrect**
**Option B:** SPECT (Single Photon Emission Computed Tomography) imaging is a useful functional imaging technique in epilepsy, particularly when used with ictal SPECT and EEG to identify seizure foci.

**Option C:** Interictal 18F-FDG PET (Fluorodeoxyglucose Positron Emission Tomography) is helpful in detecting areas of abnormal glucose metabolism in the brain, which can indicate seizure foci.

**Option D:** Video EEG with ictal 99mTc-HMPAO (Technetium-99m hexamethylpropylene amine oxime) study of the brain is a valuable diagnostic tool for localizing seizure activity and identifying seizure foci.

**Clinical Pearl / High-Yield Fact**
In cases of refractory epilepsy, functional imaging techniques like SPECT and PET can be game-changers in identifying seizure foci and guiding surgical treatment.

**Correct Answer:**
✓ Correct Answer: A. MDCT.