Non contrast-enhanced four-detector multisection CT for the detection of ring lesions in seizures

To evaluate the role of non contrast-enhanced multidetector computed tomography (MDCT) in the detection of ring lesions in the brain in patients from the Indian subcontinent, presenting with seizures.

Ninety-four patients presenting with seizures were examined using four-detector MDCT. Contiguous axial non contrast-enhanced CT of the brain was performed with a section width/section collimation of 5mm/5mm. A single axial non-contrast enhanced examinaton of section width 2.5mm was obtained through the region of interest, if necessary. This was followed by contrast-enhanced sequential imaging in all patients, using the same parameters as for unenhanced CT (i.e., 5mm/5mm). Non-contrast and contrast-enhanced CT images were recorded and reviewed separately.

In 63 out of 94 cases non-enhanced MDCT (with section width 5mm) was able to identify the ring lesions. In 11 cases, which were doubtful on unenhanced CT (5mm), performing a single examination using a section width of 2.5mm through the area of interest, helped to detect the ring lesion. Hence in 74 out of 94 (79%) cases ring lesions could be detected using unenhanced MDCT. In the remaining 21% cases, the presence of ring lesions in the brain was confirmed only after the intravenous administration of contrast medium.

Non contrast-enhanced MDCT is recommended for detecting ring lesions in the brain of patients on the Indian subcontinent, presenting with seizures. This can help to decrease the radiation dose to the patient and reduce the duration of examination. The risk of adverse reactions and patient discomfort associated with intravenous contrast medium injection are also reduced as are the costs incurred. Contrast-enhanced MDCT should be performed only in those cases in which the presence of ring lesions is doubtful on unenhanced CT.