الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
This study aimed to assess the role of conventional MRI in differentiation between GBM and PCNSL to determine the strategy of treatment.
The study was conducted on twenty patients of histopathologically proven GBM and PCNSL. They were 10 GBM patients, (6 males and 4 females) with mean age of 47.6±24.27 years and 10 PCNSL patients, (5 males and 5 females) with mean age of 61.7±11.87 years.
All of the patients were subjected to full history taking, clinical examination and conventional MRI.
MRI was performed on 1.5T Philips Gyroscan Intera whole body scanner system using a standard head coil. Conventional MRI was done and Diffusion weighted imaging with measurement of the lowest ADC values on the ADC maps.
The lesions where identified on the T1, T2, FLAIR, T1 post contrast sequences and DWI. Lesions anatomic location, number, signal intensity, pattern of enhancement, intralesion necrosis, mass effect and the surrounding perifocal edema were assessed. Also the lowest ADC value of each lesion was measured reflecting the tumor cellularity which is hyper in PCNSL than GBM.
The findings of the study were:
Conventional MRI showed the following features; all GBM lesions were located supratentorially with T1 iso to hypointense signal and T2 hyperintense signal and heterogeneous pattern of enhancement, 90% of patients showed intratumoral necrosis. The white matter dominantly affected and cortical grey matter affected in 80% of cases. Vasogenic edema was present in 90% of cases.. Diffusion restriction was detected in solid portions of the tumor in 80% of cases, while no diffusion restriction was observed in the necrotic portion of the tumor. Signs of bleeding were found in 40 % of cases. Mean ADC value for all GBM cases was 1.0. The ADC values range was between 0.62 and 1.18 ×10-3 mm2 /s.
In PCNSL patients 90% of the lesions were located supratentorial and 10% of them were located infratentorial with T1 iso to hypointense signal and T2 hyperintense signal. The pattern of enhancement was homogeneous in 80% of cases. Mild to moderate perifocal edema was present in 90% of cases. Diffusion restriction was detected in 90% of cases. Mean ADC value for all PCNSL cases was 0.76 ×10-3 mm2 /s. The ADC range for all PCNSL cases was between 0.54 and 0.9.
The ADC cut-off value to differentiate PCNSL from GBM was 0.89×
10-3 mm2/s with 90% sensitivity, 80% specificity, PPV of 81.8 and NPV of 88.9. PCNSL is diagnosed when ADC value is less than 0.89×10-3 mm2/s and GBM is diagnosed when ADC value is more than 0.89×10-3 mm2/s.