Role of Diffusion Magnetic Resonance Imaging in Assessment of Neoplastic and Inflammatory Brain lesions
Omar Mohamed Abdel Alim Abdel Hamid;
Abstract
Diffusion magnetic resonance imaging includes: diffusion weighted imaging that shows possible areas of increased or decreased signal, reflecting restricted and facilitated diffusion , respectively and the apparent diffusion coefficient in which the T2-weighted of the diffusion sequence is cancelled out, and produces numerical evaluation of interest.
Diffusion weighted MR imaging characterized by markedly decreased imaging time and increased sensitivity to signal changes due to molecular motion but having the disadvantages of decreased spatial resolution of the images and magnetic field inhomogeneities which are partially prominent in anatomic regions with air-tissue interfaces, such as the base of the skull.
The widest application of diffusion weighted imaging has been evaluation of cerebral ischemia. However it gives useful clinical information in several brain disorders besides acute stroke.
In cerebral neoplasms, ADC values have been correlated with the degree of tumor cellularity. Thus, the lowest ADC value should indicate the region of greatest cellularity which is helpful in selecting biopsy targets. DWI helps distinguish low grade gliomas (low ADC values) from cerebral infarcts (high ADC values). Tumor cellularity was inversely correlated with tumor ADC value in various grades of astrocytomas.
DWI is useful technique to distinguish areas of predominantly non-enhancing tumor (low ADC) from areas of predominantly peritumoral edema (high ADC) when the abnormality was located in the white matter aligned in the direction of the diffusion weighted gradients.
The ADC has also been used to distinguish peritumoral edema and tumor infiltration to monitor early responses to treatment, to distinguish tumor recurrence from radiation necrosis.
The signal intensity on DWI may predict the histology of metastases and their apparent diffusion coefficient values may reflect tumor cellularity.
In epidermoid tumors, DWI shows best tumor conspicuity, helps avoid confusing the tumors with arachnoid cysts, and in particular, it greatly aided in evaluation of postoperative patients.
Statistically significant differences in ADC between the cerebral lymphoma and GBM. However, the GBM with restricted water diffusion, that is, hyperintense on DW images and hypointense on ADC maps, has also been reported. Therefore; discrimination of lymphoma from some GBMs may be difficult.
Diffusion weighted MR imaging characterized by markedly decreased imaging time and increased sensitivity to signal changes due to molecular motion but having the disadvantages of decreased spatial resolution of the images and magnetic field inhomogeneities which are partially prominent in anatomic regions with air-tissue interfaces, such as the base of the skull.
The widest application of diffusion weighted imaging has been evaluation of cerebral ischemia. However it gives useful clinical information in several brain disorders besides acute stroke.
In cerebral neoplasms, ADC values have been correlated with the degree of tumor cellularity. Thus, the lowest ADC value should indicate the region of greatest cellularity which is helpful in selecting biopsy targets. DWI helps distinguish low grade gliomas (low ADC values) from cerebral infarcts (high ADC values). Tumor cellularity was inversely correlated with tumor ADC value in various grades of astrocytomas.
DWI is useful technique to distinguish areas of predominantly non-enhancing tumor (low ADC) from areas of predominantly peritumoral edema (high ADC) when the abnormality was located in the white matter aligned in the direction of the diffusion weighted gradients.
The ADC has also been used to distinguish peritumoral edema and tumor infiltration to monitor early responses to treatment, to distinguish tumor recurrence from radiation necrosis.
The signal intensity on DWI may predict the histology of metastases and their apparent diffusion coefficient values may reflect tumor cellularity.
In epidermoid tumors, DWI shows best tumor conspicuity, helps avoid confusing the tumors with arachnoid cysts, and in particular, it greatly aided in evaluation of postoperative patients.
Statistically significant differences in ADC between the cerebral lymphoma and GBM. However, the GBM with restricted water diffusion, that is, hyperintense on DW images and hypointense on ADC maps, has also been reported. Therefore; discrimination of lymphoma from some GBMs may be difficult.
Other data
| Title | Role of Diffusion Magnetic Resonance Imaging in Assessment of Neoplastic and Inflammatory Brain lesions | Other Titles | دور الرنين المغناطيسي باستخدام طريقة الانتشار في تقييم إصابات المخ الناتجة عن الأورام و الالتهابات . | Authors | Omar Mohamed Abdel Alim Abdel Hamid | Issue Date | 2014 |
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