The deterioration of indoor air quality (IAQ) in medical district was caused by the personnel in the area, the buildings and their surroundings, and the situations of the air conditioning system. It is necessary to control the personnel entering the medical area and to strengthen the management of the buildings and their surroundings, and the air conditioning system for maintaining high IAQ. The development of new efficient air cleaning (equipment) is of importance in the same way.

Objective To examine the feasibility by applying the CT density-difference postprocessing in early diagnosis of middle cerebral artery (MCA) occlusion. Methods The possible MCA occlusion patients were scanned with CT in early stage (within 3 hours) and divided into two groups randomly.Each group included 50 samples and one was processed technologically by CT density-difference and the other one was not.The two groups were scanned once more in 24 hours later and the data being processed by statistical method. Results The results showed that the accurate diagnosis rates were 14.3% within 60 minutes,93.3% from 60 to 119 minutes and 100% from 120 to 180 minutes .In comparing these two groups,there appeared no significant differences in the situation within 60 minutes and there was found significant difference in the other two situations. Conclusion Applying the technology of CT density-difference postprocessing,the middle cerebral artery (MCA) occlusion in early stage might be diagnosed.

Objective To investigate the clinical and characteristic imaging findings of intracranial gliosarcoma. Methods The imaging findings of surgery and pathology proved intracranial gliosarcoma in 15 cases were retrospectively analyzed. There were 10 males and 5 females, ranging in age from 44 to 67 years (mean age 58 years). Results All tumors were located in supratentorium, including 13 cases in the temporal or parietal lobe, 1 cases in the occipital lobe, and 1 cases in the thalamus. Tumors appeared as round or ellipse in shape. The lesions ranged in size from 3 to 9 cm (mean 4.6 cm). CT scan showed mingled hypo and isodensity in 7, hypodense in 4 with CT value from 18 to 22 HU, hyperdense in 4 with the CT value from 48 to 55 HU. Enhancement appeared as an irregular pattern. The margin was clear. Most intracranial gliosarcoma showed perifocal edema. MRI were examined in 6 cases, whichappeared as low signal on T 1WI, and as high signal on T 2WI. There was irregular enhancement of the mass. Conclusion It was difficult to make the correct preoperative diagnosis for gliosarcoma, but it was possible to make a tendency diagnosis using CT or MR combined with the history. Contrast enhanced CT and MRI should be useful in differentiating gliosarcoma from glioblastoma.

Objective To investigate the characteristic clinical, imaging, and pathologic findings of intracranial neuronal and mixed neuronal-glial tumours. Methods The imaging findings of surgery and pathobiology proved intracranial neuronal and mixed neuronal-glial tumours in 14 cases (7 male and 7 female, ranging in age from 6-56 years; mean age 33.8 years) were retrospectively analyzed. Results Eight gangliogliomas were located in the frontal lobe (4 cases), temporal lobe (1 case),fronto- temporal lobe(2 cases), and pons (1 case). They appeared as iso-or low density on CT, iso-or low signal intensity on T 1WI, and high signal intensity on T 2WI on MR imaging. Two central neurocytomas were located in the supratentorial ventricles. Four desmoplastic gangliogliomas were seen as cystic masses, appearing as low signal intensity on T 1WI and high signal intensity on T 2WI Conclusion Intracranial neuronal and mixed neuronal-glial tumours had imaging characteristics. Combined with clinical history, it was possible to make a tendency preoperative diagnosis using CT or MR.

Objective:To analyse the imaging featrues of intractranial tuberculoma and improve the diagnostic accuracy.Methods:31 patients with clinical characteritics and pathological proved intracranial tuberculomas were studied retrospectively.Results:"egg-shell"calcification were the feature of giant calcified and ossified tuberculoma.CT scaning were single and multiple nodular lesion.In the contrast enhancing CT scaning,plate shaped or ring form shadows were shown.MRI were provided hypointense on T1WI and hyperintense on T2WI.The rim homogeneous enhancement were showd in the Gd-DTPA.Conclusion:The diagnosis of typical intracranial tuberculomas can be made.After antituberculosis chemotherapy,CT and MRI can help made differsntial diagnosis.Operative indications should be select strictly.

Objective To explore the technique and the clinical value of Neuroform stents in combination with Guglielmi detachable coil(GDC) to treat wide-necked basilar artery aneurysms.Methods 30 cases with wide-necked basilar artery aneurysms were treated with Neuroform stent combined with GDC.Of 30 wide-necked basilar artery aneurysms,the location of lesions was at basilar tip in 16,basilar trunk in 9 and the beginning of the basilar in 5.Results In 30 cases,total occlusion was achieved in 25 and partial occlusion in 5 patients.The thrombosis within stent occurred in 2 patinets,and remainder of patients recovered well.There were no thromboembolic events in 20 cases followed up for 3~6 months.Twenty-two patients were angiographically followed up for 3 months after the procedure,among them,the aneurysms visualized and the arteriae burdened aneurysms were passed free in densely packed and 3 aneurysms with neck remnant.Conclusion The Neuroform stent is a easy and safe intracranial stent for embo1ization of wide-necked intracranial aneurysms,especially suitable for wide-necked basilar artery aneurysms with severely tortuous intracranial artery.

Objective To study the correlation among pathological,clinical and the imaging features(CT and MRI) of the Rathke cleft cysts.Methods CT,MRI and clinical findings of Rathke cleft cysts in 43 patients confirmed by operation and pathology were retrospectively studied.Results 27 cysts located at intrasella and suprasella and 16 cysts entirely located at intrasella.Cysts were round or oval in shape with definite borders.The size of 30 cysts exceed 10mm in diameter.On CT scans reviewed,the cysts were low density in 9 cases,hyper-density in 9 cases and isodensity or mixed density in 8 cases.The cyst's wall with calcification was seen in one.On postcontrast CT scans,6 cases showed circular and peripheral cyst's wall enhancement and others were no enhancement.On MR imaging,the lesions were low or isodense on T1WI and hyper-intensity on T2WI in 18 cases,both were high signal intensity on T1WI and T2WI in 6 cases,high signal intensity on T1WI and mixed signal intensity on T2WI in 4 cases.An intracystic nodule having high signal intensity on T1WI,and low or mixed signal intensity on T2WI was observed in 4 cases.On contrast-enhanced MR imaging,enhancement of the cyst's wall was shown in 9 cases.During surgery,the lesions were noted to have a cyst of semisolid consistency,and cystic contents were described from CSF-like clear fluid in 10 cases,jellied-like brown mucoid fluid in 15 cases,caseous-like mucoid fluid in 12 cases,machine oil-like mucoid fluid in 6 cases.At histopathology,a part of cystic fluid included cholesterol crystal and necrotic debris.Cholesterol clefts and hemosiderin pigment,and granuloma were shown by staining with HE in 11 cases.The PAS staining was positive in 16 cases,cystic fluid contained partial mucopolysaccharides and protein.Conclusion Typical Rathke cysts can be dignosised in the preoperative,the findings of CT and MRI are not specific in atypical cysts.The imaging features were different with the fluid component of Rathke cleft cysts..

Objective To study CT and MRI features of intracranial chondrosarcomas. Methods CT and MRI of 3 cases with intracranial chondros arcomas proved by pathology were retrospectively analyzed.Results CT scans showed the tumors were lobular mass, per itumoral edema were not serious, intratumorous calcification and bone invasion w ere seen in 2 cases.MRI showed that tumor had low to intermediate signal intensi ty or hypointensity on T 1WI, high signal intensity on T 2WI. On contrast enha nced MRI,the center of lesions which was low signal intensity on T 2WI was no e nhancement, but there was observable enhancement at periphery of tumors.Conclusion Intracranical chondrosarcomas are often orgina ted from synchondrosis of the skull base,the lesions are often associated with c alcification, and bone invasion, the accurate dignosis should depend on microsco pic examination and immunohistochemical staining.

Objective To analyse imaging features of atypical meningioma.Methods There were 17 cases with atypical meningiomas proved by pathology,7 cases were male,10 cases were female,ranged in age from 34～69 years.17 cases all examined with CT,and 10 cases with CT enhanced scanning;12 cases examined with MRI and 8 cases with MR enhanced scanning,5 cases examined with DSA.Results The major imaging features of atypical meningioma included:the borders of tumors were mostly irregular,nonhomogeneous density or signal on plain CT and MRI,nonhomogeneous enhancement on enhanced CT and MRI.Cystic and necrotic changing and the invasion of cranial bone and adjacent structure could be seen.5 cases with dural tail sign on MRI,3 of them,this sign was short,thick and irregular.Heavy staining was showed on DSA.Conclusion Atypical meningiomas are of some clinical and imaging features.

Objective To study the clinical law and imaging characteristics of intracranial primary malignant lymphoma.Methods The clinical law and imaging finding in 27 cases of intracranial primary malignant lymphoma confirmed by pathology were analysed CT scan was performed in all cases.MRI examination were carried out in 20 cases simultaneously.Results The first symptom in most cases was headache,and other symptoms were epileopsy,dizziness,hemiplegia,etc.This lesion was mostly seen in male around 40 years old.The lesions were mostly equal or high density on CT,equal or low signal intensity on T 1WI and closed to grey matter signal intensity on T 2WI.Tumors were enhanced obviously on contrast-enhanced scans,necrosis of center of focus was seen in 1/3 cases.The lesions were single or multiple.Conclusion The accuray diagnosis of intracranial primary malignant lymphoma can be done by combined clinical data with imaging features.