Determination of the reliability of Computerised Tomography (CT) for diagnosing intracranial gliomas

Abstract

Back ground: Brain imaging was rcvolutioniscd by the introduction of cornputcriscd tomography (CT) by Hounscfield in 1973. While more novel imaging modalities such as

magnetic resonance imaging (MRI), single photon emission tomography (SPECT), positron emission tomography (PET) and magnetoencephalography (MEG) have virtually dislodged CT from this pivotal role ill the developed world, in Kenya, CT which is more readily available and affordable has remained a key diagnostic tool in neuroimaging I. Despite the technical limitations of the CT scanning in the view of poor characterisation of tissues based on the single parameter of the electron flux density, it is capable of identifying most intracranial mass lesion. The ability ofCT to visualise calcifications is a significant advantage which when depicted in the brain neoplasm serve to modify the list of differential considerations 1,2. Despite CT been readily available in our set up, no study has been carried out to elucidate the utility of CT in the evaluation of surgically proven intracranial gliomas Objective: To determine the reliability ofCT for diagnosis of intracranial gliomas. Desiun: Prospective comnarativc hosnitai basco SUIOV Oil SIXIV JlVC naucnrs over n' period between March 2005 and March 2006. Setting: The study was carried out in the departments of neuro surgery and histopathology at Kenyatta National Hospital (KNH). Subjects: Sixty-five patients including thirty eighty males and twenty seven females aged between two years and eighty eight years took part in the study. Method: Patients with an intra cranial space occupying lesion (SOL) suspected to be a glioma at CT were considered. The patients included in the study were those who, in addition to imaging underwent surgery which enabled histological characterisation of the lesion. Informed consent was obtained from the patients before recruitment. Results: A slight male preponderance was found in most of the glioma subtypes. Glioblastoma multifonne (GBM) was the commonest glioma sub type 33.8<Yo. Blaill siem glioma was the most reliably diagnosed lesion at CT 100% specificity and 100% sensitivity. The sensitivity and specificity of the other gl ioma subtype was as follows respectively: pilocystic astrocytoma 75.0% and 98.4%; oligodendroglioma 50% and 96.5%; ependymoma 50% and 95.1%; glioblastoma multiforme 50% and 86.5% while for low grade astrocytoma was 87.5% and 96.5%. Conclusion: The results obtained in this study show that CT scan examination is a reliable radiological tool for the diagnosis of intra - cranial gliomas in the setting of the Kenyatta National Hospital.