Measurements of Optic Chiasm Dimensions using Magnetic Resonance Imaging

Abstract

Knowledge of the normal size range of the optic chiasm can be helpful in the early detection of some disorders, The height and width of the optic chiasm can be measured with the use of commercially available software, which allows an objective estimate of the chiasm’s size, most magnetic resonance units now in use have the capabilities to furnish the region of interest measurements. The aim of this research was to identify the dimensions of optic chiasm in magnetic resonance imaging of the brain using coronal cuts. This retrospective and prospective study included 205 Sudanese patients, 89 patients (43.4 %) were females 116 patients (56.6%) were males with different ages ranges (between 16-78 years old) referred to Radiology Departments of Royal Care Hospital and Antalya Medical Center in Sudan, in the period between 2015 to 2018. All the patients underwent MRI brain, diagnosis by experienced radiologists, 172 patients were diagnosed as a normal brain, and 33 patients having pathological changes, all measurements of optic chiasm were done on coronal cuts of brain magnetic resonance imaging using general protocol. The mean width ± standard deviation (SD) of the optic chiasm for the normal patients was: 13.04 millimeter ± 1.21 and the mean ± SD of the height was: 2.46 millimeter ± 0.14. The mean width ± SD of the optic chiasm for the abnormal patients was: 13.32 millimeter ± 1.28 and the mean ± SD of the height was: 2.53-millimeter ± 0.184, for all samples normal and abnormal the mean width± SD of optic chiasm was 13.08 millimeter ± 1.22, mean width± SD V height was 2.47 millimeter ± 0.154, the range of the Sudanese optic chiasms width between 10.18 millimeter and 15.12 millimeter± 1.2 standard deviations and a height between 2.11 millimeter and 3.04 millimeter ±0.15 standard deviation can be considered definitely normal. Chiasms measurements outside these ranges should be considered abnormal and prompt further investigation. Correlation between age and gender yielded no significant differences. The study concluded that the calculated measurement of the normal optic chiasm on brain magnetic resonance image can be used as a comparative standard by which to detect relatively smaller or larger chiasms, and added basic and important information to the dimensions of chiasm measurement in the Sudanese population and will positively affect the early diagnosis of some diseases in the future. The study recommended that the future researches should be done with coordination of ophthalmologists and radiologists using the large sample of abnormal subjects.