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 study the possibility of microvascular permeability (PS) value derived from perfusion CT (PCT) in predicting hemorrhagic transformation (HT) in acute cerebral infarction in elderly patients.Methods 52 consecutive patients with middle cerebral artery acute ischemic stroke who received thrombolytic therapy were divided into HT group and control group,and patients in HT group were further divided into hemorrhagic infarction (HI) group and parenchymal hematoma (PH) group.PCT data and Alberta stroke program early CT scores (ASPECTS) from CT angiography source images (CTA-SI) achieved within 6 hours after symptom onset of each group was retrospectively analyzed and statistically processed.Results In 52 patients,there were 22 cases developed HT,14 cases with HI,8 cases with PH.Cerebral blood flow (CBF) and cerebral blood volume (CBV) values were decreased and permeability surface area product (PS) was increased in ipsilateral in HT group and control group as compared with the contralateral (all P＜0.05).PS value in ipsilateral was significantly higher in HT group than in control group (P＜0.01),but CBF and CBV values in affected side showed no significant difference between the HT group and control group.The area under the receiver operator characteristic (ROC) curve of PS Az value was 0.968.When PS ≥5.77 ml · min-1 · 100 g-1,the sensitivity and specificity of predicting HT were 95.5％ and 86.7％ respectively.The ASPECTS was lower in HT group than in the control group (P＜0.01),and ASPECTS was higher in HI group than in PH group (P＜0.01).The differences in PCT results in affected side between the HI group and PH group was not significant.Conclusions The significantly increased PS value can be a reference in predicting HT risk and guiding thrombolytic therapy.

Purpose:To discuss the MRI features and differential diagnosis of hemangioblastomas in the central nervous system.Materials and Methods: The MRI features of 22 patients with hemangioblastomas confirmed histopathologically were analyzed retrospectively.Results: In this group there were 50 lesions in 22 patients.Multiple lesions were revealed in 5 cases.The lesions located in the cerebellar hemisphere and vermis ( n = 40),medulla oblongata and spinal cord ( n.= 9 ),cerebral hemisphere ( n = 1).Among the 50 lesions,12 appeared as a large cyst with mural nodule,36 as a solid mass,2 as a simple cyst.Of large cyst with mural nodule lesions,the content of the cyst was hy-pointense signal on T1WI,and hyperintense signal on T2WI.The mural nodules were slightly hypointense signal or isointense signal on Tl WI,and hyperintense signal on T2WI.The solid masses were isointense signal on Tl WI,slightly hyperintense signal and hyperintense signal on T2WI.On contrast enhanced scans,all mural nodules and solid tumors were showed marked homogeneous enhancement.On PWI the mural nodules and solid tumors were demonstrated marked hyperperfusion.Conclusion:Hemangioblastomas have distinctive manifestation,MRI enhanced scans and PWI play an important role in the diagnosis and differential diagnosis of hemangioblastomas.

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 assess the clinical value of MSCT in diagnosing the overcrowding of osteal posterior cranial fossa (PCF) in adults.Methods MSCT images of a cohort of 52 adult patients with foramen magnum osteal malformation confirmed by surgery (diseased group), and 100 healthy adults (control group) were retrospectively reviewed.Images post-processing techniques included multi-planer reformation (MPR) and volume rendering (VR).The posterior cranial fossa volume (PCFV), posterior cranial fossa height (PCFH), clivus length (CL), clivus gradient (CG), supraocciput length (SL), and anteroposterior diameter of the foramen magnum (FMD) were measured on sagittal images in 52 patients and 100 normal adults.Independent-sample student's t test was used to compare the differences between patients and normal adults.Results The results of PCFV, PCFH, CL, SL,FMD and CG, male of control group were (168.2 ±12.3) cm~3, (38.2 ±1.2), (47.1 ±2.8), (41.1 ±1.8), (36.6 ±4.9) mm, (51.5±3.6)°, female of control group were (157.5 ±10.2) cm~3, (36.5 ±1.4), (46.2 ±2.2), (39.7 ±1.3), (35.2 ±3.8), (49.6±3.1)° ;diseased group were (128.7 ±11.7) cm~3, (30.6 ±1.9), (36.2 ±1.4), (37.3 ±0.9), (33.9 ±3.5)mm, (44.5 ±2.8)° .There was significant sex difference in PCFV, PCFH, CL, SL and CG in control group (t =4.70, 6.44, 4.84, 4.43 and 2.81 respectively, P<0.01), but FMD was not significant(t=1.97,P>0.05); the results of PCFV, PCFH, CL, CG and SL were significant different between diseased group and male of control group (t=16.62, 24.04, 25.01, 14.17 and 10.99 respectively,P<0.01) ; the results of PCFV, PCFH, CL, CG and SL were significant different between diseased group and female of control group (t=13.23, 17.80, 27.50, 11.67 and 8.73 respectively,P<0.01) ;but there were no significant differences of FMD between diseased group and control group, both male and female (t=2.96,2.07, P> 0.05).Conclusions The overcrowding of PCF can be accurately measured by MCST.As a routine preoperative examination, MSCT is helpful in the therapeutic selection and the anatomic and pathologic study of PCF.

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.