Abstract
The periventricular hyperintensity (PVH for short) is the high intensity area seen in the white matter around the lateral ventricle of the brain on MRI, which is thought to partly correspond to the periventricular lucency on X-ray CT. With X-ray CT, it is believed to express the hydrocephalic or ischemic changes. MRI is more sensitive to the tissue contrast, so more accurately the presence and the extent of PVH can be diagnosed by MRI. The frequency of patients with PVH on MRI was investigated and discussed in relation to aging or cerebral ischemia. Subjects for study were 244 of normal cases and 112 of patients with diagnosis of various ischemic cerebrovascular diseases. None of these subjects was younger than 10 years old. Normal cases consisted of the normal volunteers or other patients of normal MR images and did not include the patients with neurological sign or the patients of demyelinating disease, connective tissue disease, or dementia. The NMR-CT used was the about 0.14 Tesla resistive type. The Carr-Purcell-Meiboom-Gill method, one of the multispinecho sequences, was chosen for the pulse sequence of imaging. Confirmation of PVH around the lateral ventricle was performed and percentage of patients with PVH against all patients was calculated on each decade. These results showed that in normal cases the frequency of PVH was as low as about 5% under 40 years old and that it increased significantly with age over 40 years old. In patients with cerebral ischemia, the frequency of PVH increased significantly more than that in normal cases on each decade. By the regional study, the frequency was higher around the anterior horn and the body of the lateral ventricel, especially around the anterior horn in both normal cases and patients with cerebral ischemia. Conclusion derived from these results was that PVH was releated to factors common to both aging and cerebral ischemia. One cause of PVH could be the direct reflection of ischemic lesions, such as lacunar infarcts or edema, because the periventricular white matter is thought to be an end and border zone of the arterial blood supply and a region which often falls into ischemia. Another reason for the increase of PVH with age or cerebral ischemia might be the increase of extracellular fluid caused by hypofunction of the lesser pathway of cerebrospinal fluid circulation. This pathway represents the absorption by the parenchymal vascular system, and its function is obstructed by cerebral arteriosclerosis, small infarction, or other age changes. In summary, we belive that PVH is apparently related with cerebral ischemia or other age changes and that it should be regarded as an important finding suggestive of the cerebral aging.
