RETROSPECTIVE EVALUATION OF MRI PATTERN OF GLIOBLASTOMA IN A TERTIARY HOSPITAL IN NIGERIA

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G.I. Ogbole¹, O.A.Ogunleye¹, M.C. Nweke², J.A. Akinmoladun¹

1. Department of Radiology, College of Medicine, University of Ibadan and University College Hospital, Ibadan.
2. Department of Pathology, University College Hospital, Ibadan.

Abstract

Introduction: Malignant gliomas, especially glioblastomas, are among the most aggressive and devastating of cancers, commonly producing profound progressive disability and leading to death in most cases. Conventional magnetic resonance (MR) imaging with gadolinium-based contrast agents is the most widely established and most useful tool in the characterization of cerebral tumors including Glioblastomas. This study aims to describe the imaging characteristics of Glioblastoma in African patients using conventional MR imaging.

Methodology: This was a retrospective cross-sectional study carried out at a Nigerian tertiary hospital. The demographic data, MR images and reports of patients with imaging and histological diagnosis of Glioblastoma between January 2003 and September 2017 were retrieved and reviewed. All the recorded data were analyzed using simple proportion and descriptive statistics with the Statistical Package for Social Sciences (SPSS) version 20.0 software for Windows.

Results: One hundred and twenty-two (122) patients had brain tumors during the review period, out of which 14 (11.5%) had histologically confirmed glioblastoma. The male- to -female ratio was 2.5 to 1.0. The age ranged between 14 and 72 years with a mean age of 49.6 years SD ±16.3. Twelve (85.7%) patients had solitary tumors and 2 (14.3%) had multiple tumors. Six (42.9%) were found on the right hemisphere only, 5 (35.7%) were found on the left hemisphere while 3 (21.4%) traversed both hemispheres. All tumors showed in homogeneous enhancement and significant midline shift to the contra-lateral side of greater than 3mm. Only 1 (7.1%) tumor showed evidence of intra-tumoral bleed detected on T2* sequence.

Conclusion: Glioblastoma is a known aggressive brain tumor with unique MR imaging characteristics. While midline shift is typical, intra-tumoral bleeding may be an uncommon finding at presentation in our center.

Keywords: Glioblastoma, Magnetic resonance imaging, Brain, Tumor, Pattern.

Introduction

Malignant gliomas are considered to be the most aggressive and devastating of cancers, commonly producing substantial and progressive disability leading to death in most cases.¹ They present some of the greatest challenges in the management of cancer patients worldwide and are the most common malignant primary brain tumors in adults with an annual incidence of 4 to 5 in 100,000 people.^2–5 Glioblastomas account for approximately 60 to 70% of malignant gliomas. Gliomas are categorized by the World Health Organization (WHO) into four grades: grades I – IV, based on histological characteristics, which carry prognostic and survival correlates. Glioblastoma is a diffuse WHO grade IV glioma, which is the most malignant grade. Some gliomas of lower WHO grade have been known to recur, progress, or transform into Glioblastoma.³ Glioblastomas arising de novo are termed primary while those arising from a previously documented lower grade glioma have been termed secondary. The demographic, molecular and survival characteristics of these two types are very varied. The mean age of primary glioblastoma patients is about 55years, while the mean age of secondary Glioblastoma patients is much lower- around 40years.⁶ Primary Glioblastomas occur more frequently in males than in females (M:F ratio = 3:1),^3,7–10 while the secondary Glioblastomas occur more frequently in females (M:F ratio = 2:3).⁷ Glioblastoma is also known to be commoner in Caucasians than Blacks and Asians.^2,5,11–13 with the white to black ratio being put at 2:1.^2,5 The reason for this increased prevalence in whites is not known. The overall survival in secondary Glioblastoma is better than in primary Glioblastoma which usually runs a shorter clinical course.

The cause of Glioblastoma is however unknown. A known risk factor includes exposure to ionizing radiation.^2,3,14 Evidence of associations with head injury, foods containing N-nitroso compounds, occupational risk factors, and exposure to electromagnetic fields remain inconclusive.^2,14,15 There have been previous concerns about the increased risk of Glioblastoma with the use of cellphones16 however several larger studies have failed to demonstrate this.^3,14,17,18

Approximately 5% of patients with malignant gliomas have a family history of gliomas with some of these familial cases associated with rare genetic syndromes, such as neurofibromatosis types 1 and 2, the LiFraumeni syndrome (germ-line p53 mutations associated with increased risk of several cancers), Turcot’s syndrome (intestinal polyposis and brain tumors), and Cowden’s disease. ^2,15,19,20 Gene polymorphisms that affect detoxification, DNA repair, and cell-cycle regulation have also been suspected to be involved in the development of gliomas.^2,14

Patients usually present with non-specific symptoms such as progressive headache, confusion, memory loss, focal neurologic deficits and seizures. Rarely, in less than 2% of cases, patients may present acutely with stroke-like symptoms and signs.²¹

Conventional magnetic resonance (MR) imaging with gadolinium-based contrast agents is the most widely established and most useful tool in the characterization of cerebral tumors.^22-25 With optimal technique and sequences, modern MR systems provide excellent anatomic or morphologic imaging of gliomas. MR imaging also provides information regarding contrast enhancement, peripheral edema, distant tumor foci, hemorrhage, necrosis and mass effect. More than 90% of all GBMs will show at least some enhancement, usually in an irregular, occasionally nodular, ring-like pattern.

Advanced MR imaging techniques such as timed perfusion MR imaging and proton MR spectroscopy have increased utility in demonstrating tumor cellular activity to correlate reliably with histologic findings for appropriate grading.^26-31

Glioblastoma majorly occurs as a unifocal disease but can be multifocal having multiple lesions in the brain, mimicking brain metastases or other ring enhancing lesions.

The overall survival in GBMs is still averagely between 6 months and two years. Prognosis is poor and negative prognostic factors include deep location (e.g. thalamus),increased age and a low pre-diagnosis functional
status.²¹

In this report, we describe the imaging characteristics and tumor pattern of Glioblastoma seen among native Africans in a tertiary hospital in Nigeria using a lowfield MR system.