A 45-year-old female had a tumor in the parietal region of brain which was resected 2 years back. Now she presents with headache, vomiting and deterioration of consciousness. What investigation you will do now?

Ans: A. > C (CT > 18 FDG-PET) Ref: Schwartz Textbook of Surgery, 10th edition, pg: 1713Explanation:The most important keyword in history is "Deterioration of consciousness".In an acute setting, when patient presents with Coma the investigation of choice is CT scan.In an elective situation, the best investigation would be 18 FDG-PET.Imaging in Brain TumoursCT ScanIt is the investigation of choice in emergency situation when patient comes with decreased GCS.Headache, nausea, vomiting and progressive mental status decline are indicative of increased intra cranial pressure.CT scan is used to rule out increased intra cranial pressure and midline shift due to recurrent tumor. Decision to take the patient for surgery depends on CT findings.MRI BrainIt is used in elective situation for diagnosis of brain tumors.MRI is very helpful in identifying tumors in the posterior fossa (including acoustic neuromas), hemorrhagic lesions.MRI is also investigation of choice for diagnosing Brain Metastasis.PET-ImagingMetabolic imaging tool that is able to distinguish between benign and malignant tumours.18 FDG-PET and HMPAO-SPECT are used to differentiate between tumor recurrence and fibrosis at the site of operation. This has to be done in an elective situation.Single-photon emission computed tomography (SPECT) is a nuclear medicine tomographic imaging technique using gamma rays.The gamma-emitting tracer used in functional brain imaging is99mTc-HMPAO (hexamethylpropylene amine oxime).Fluorodeoxyglucose (FDG) is used in PET scan. FDG uptake is increased in most malignant tissues.The sensitivity of 18 FDG-PET is better than MRI and CT in diagnosing residual and recurrent brain tumours.