A rough estimation of the incidence of SSEH is provided,and the results confirm the previously described association with minor trauma and anticoagulant therapy and low frequency of arteriovenous malformations.

In five patients with clinical suspicion of spinal disease, MRI of the spine revealed unexpected aortic pathology explaining the symptoms. No significant intraspinal pathology was found on MRI. However, in one patient with clinical suspicion of spinal stenosis, an aortic occlusion was detected on MR images of the spine. The lower extremity ischaemia, caused by the occlusion, was responsible for the symptoms. In another patient a paravertebral haematoma from a ruptured aortic aneurysm resulted in spinal nerve compression, thought before MRI to be caused by a spinal tumour. In three patients aortic aneurysm or dissection resulted in spinal cord ischaemia with symptoms mimicking those of compressive spinal disease. Thus, if MRI of the spine does not provide an explanation for the patient's symptoms, examination of the aorta is recommended.

Objective-To investigate patients with cystic enhancing lesions on CT and to determine whether thallium-201 ( 201 Tl) SPECT adds to further preoperative information in diVerential diagnosis between gliomas and abscesses. Methods-Twenty one patients with cystic ring enhancing CT findings were studied and uptake indices were compared with CT enhancement volumes, histopathology, and survival times. Results-Fourteen high grade gliomas, three low grade gliomas, and four abscesses were found. Uptake was higher in the highly malignant glioma group (median thallium index (TI)=2.1), than in the low grade glioma group (median TI=1.4) or among the abscesses (median TI=1.6). Overlapping indices were found between high and low malignant cystic gliomas as well as between either one of the glioma groups and the infectious lesions, and there were no significant diVerences between groups. There was a level at the value 2, where TI>2 correlated with tumour diagnosis. One low grade tumour had an extremely high index and a very high enhancement volume. Indices correlated significantly with CT enhancement volumes (P=0.005). There was no significant correlation between Tl indices and patient survival times among the high grade gliomas. One patient with a highly malignant tumour but low Tl uptake <2, had a survival> five years. Conclusions-It is concluded that high 201Tl uptake in enhancing cystic lesions is an indicator of highly malignant glioma. However, the diVerentiation between the high malignant gliomas and abscesses or low malignant gliomas by 201 TL SPECT is only partial with an overlap between these groups.