A propective review of the imaging findings in magnetic resonance imaging of the brain

Abstract

A prospective study was conducted at the Diagnostic Center in Nairobi, Kenya between the period January 1 - December 31 2003. The aim of the study was to analyze the pattern, age and sex distribution of cranial pathologies as shown by MRI, and to compare the findings of MRI with CT scan for diagnosis of cranial pathologies. The sample population included patients who had undergone a cranial MRI examination at the Diagnostic Center during the study period. A total of 565 cases were analyzed. The age of the patients varied from 2 months to 86 years. There were 300 (53.1%) male patients and 265 (46.9%) female patients, giving a male to female ratio of 1.13: 1. The single most common symptom recorded in the 565 patients was headache, which was seen in 157 (27.8%) patients. Other symptoms (nausea, vomiting, memory loss, visual impairment, vertigo, weakness of limbs and face, hearing impairment dementia, etc.) with or without headache were observed in 408 (72.2%) patients. Ischaemic changes were the frequently diagnosed intra-cranial pathologies, being present in 48 patients (8.5%). The mean age of patients diagnosed with ischaemia was 56 years, while the male to female ratio was 3: 1. Dementia constituted the major presenting symptom, seen in 20 (41%) patients, followed by twitching and numbness around the /ips in 8 patients (16%). The regions most frequently involved in ischaemic changes were the peri ventricular and para ventricular areas (35%) followed by parietal lobe (31 % of cases). Ischaemic changes were characterized by increased Signals on T2W images. Infarction was diagnosed in 45 patients (8%). Out of these 12 patients had lacunar infarcts. The mean age of patients diagnosed, as having infarction was 62 years with male to female ratio of 1.5.1. Infarction was most frequently found in the region of parietal lobe (26%), followed by frontal lobe (13%). Mean age of patients diagnosed, as having lacunar infarction was 65 years. Lacunar infarcts are found most frequently in thalamus (25%), followed by basal ganglia region (20%). Acute infarctions were characterized by high Signals on T2Wand FLAIR images. Chronic infarctions were characterized by a high signal on T2W images and associated changes such as brain atrophy and encephalomalacia. Tumors were diagnosed in 48 (8.5%) out of the 565 patients. The mean age of patients diagnosed with tumor was 41 years. The female patients constituted 48% and male patients constitute 52% of cases giving a male to female ratio of 1.1:1. Headaches along with other symptoms (vomiting, cerebellar signs, nerve symptoms) were the most common presenting symptoms in patients with tumors, being present in 50% of patients. Glioma was the most frequently diagnosed tumor (14 patients) followed by meningioma (8 patients). Tumors were most frequently distributed in the frontal lobe (20.8%) and parietal lobe (20.8%). Infection was diagnosed in 16 (2.8%) patients. The mean age of patients suffering from infection was 27 years with a male to female ratio of 1.6:1. Headaches along with other symptoms (fever, nausea, vomiting, photophobia, convulsions) were the main presenting symptom being present in 45.8% of the patients. The region most frequently involved was the parietal lobe (43.75%). Infective lesions were characterized by low signal on T1W and high signal on T2W images, with post contrast enhancement. Demyelinating conditions were diagnosed in 19 (3.4%) patients. The mean age of the patients diagnosed as having demyelination was 34 years with male to female ratio of 1.3: 1. Headache and convulsions were the most common presenting symptoms. The lesions were characterized by high signal on T2W and FLAIR images. Intracranial bleeds were diagnosed in 8 patients, whose mean age was 53 years and having a male to female ratio of 1.8:1. 75% of the patients had subacute subdural bleed, characterized by high signal on T1W and T2W images. AV malformation was diagnosed in 3 patients having a mean age of 35 years, and a male to female ratio of 1:2. Mesial temporal sclerosis was diagnosed in 9 patients having a male to female ratio of 2:1. Convulsion was the most common presenting symptom (85%) in this condition. The lesions were characterized by increased signal on T2W images and reduction in size of the hippocampal region with dilatation of the temporal hom. A follow up examination was performed in 65 patients whose mean age was 40 years and a male to female ratio of 1: 1.3. Out of these 65 cases for follow up, 31 cases had tumor, 11 cases had intra-cerebral bleed and 5 cases had intra-cranial infection. 244 (43.2%) cases were normal. The mean age of presentation was 37 years with male to female ratio of 1: 1.1. Among the normal patients the most common presenting symptom was headache (seen in 60.7% of cases). MRI was found to be more useful than CT in detecting intracranial pathologies especially infarction, demyelinating conditions, Mesial temporal sclerosis and infection. The reliability of the MRI technique in diagnosing intra-cranial lesions is discussed. It is hoped that the results of this study will enhance the use of the MRI technique in the diagnosis of intra-cranial lesions.