0.05 ) . For diagnosis of intracranial aneurysms by VR , sensitivity , specificity, accuracy, positive predictive value and negative predictive value were 96.8%, 92.9%, 95.9%, 97.8% and 89.7% respectively,while sensitivity , specificity, accuracy, positive predictive value and negative predictive value of DSA was 97.9%, 96.3%, 97.5%, 98.9%, 92.9% respectively. Of all 94 aneurysms, 3D spacial relationship of neck, body and parent artery of aneurysms could well demonstrated by VR in 89,while by DSA only in 57(60.6%). Conclusion MS 3D-CTA VR is a very quick ,economical and effective method in diagnosis of intracranial aneurysms and has very high sensitivity , specificity and accuracy.

Objective To understand further the CT signs of small peripheral lung cancer and to improve its diagnostic rate by CT.Methods 63 patients with small peripheral lung cancer(diameter was approximately 3 cm)were examined with spiral CT scanning before operation.All cases were confirmed by surgery and pathology.And additional high resolution spiral CT scanning was done in 28,and enhanced CT scanning was done in 41 of them.The size,edge signs,internal texture and enhanced degree were analyzed.Results Of 63 cases,CT findings included the lobular sign in shape in 57,burr sign in 56; sign of hollowed pleura in 48; sign of blood vessel bundle in 36; sign of small bubbles in 15; sign of air bronchus in 6.Of 41 cases with additional enhanced CT scanning, the increasing range in CT value of 34 cases was over 30 HU.Conclusion Peripheral pulmonary nodules which are of more than 3 edge signs on CT are highly suspected to be peripheral pulmonary carcinoma.Enhanced CT scanning is very helpful in distinguishing benign and malignant pulmonary nodules.

Objective To evaluate the value of spiral CT in analyzing correlation of growth pattern with pathology and prognosis in gastric stromal tumor(GST).Methods CT findings and pathological data including immunohistochemical staining sections of 43 patients with GST were reviewed and all patients were followed.The correlation between growth pattern,pathology and prognosis was studied.Results Of the 43 GST,there were benign in 9 and malignant in 34.the benign or malignant GST closely correlated with the growth pattern.Of the 17 intra-and extra-luminal growth patients,16 cases were malignant and 5 cases recurred in 3 years.Conclusion The GSTs that appear intra-and extra-luminal gowth hint the poor prognosis.