| Objective:Evaluating the effect on normal structures and image quality of low-dose chest MSCT;Comparing of low and conventional dose MSCT of displaying lesions characters including nodules or masses ,diffuse lesions and central airway lesions and of difference of reconstructive imaging quality;assessing the utility of low-dose MSCT for CT-guided biopsies; Then sdudying the application value of low-dose chest MSCT in clinical work.Materials and methods:Low-dose chest MSCT was performed in 256 patients of2003.10.10-2004.1.13 in which 172 cases can be adopted,including 60 health examination cases,42 cases with nodule or mass,38 patients suspected diffuse disease,32 patients with central airway lesion and 10 patients undergong CT-guided chest biopsies.All patients were scanned on a Mx8000 4 CT scanner.For comparison study,all whole lung scanning adopted 2.5mm collimation,p=l .25 and 120 Kv.All conditions were identical except the tube current in two dosage scanning.According to literature, most authors think images scanned with 50mAs cannot affect the detection of nodules.50 mAs was used in all low-dose scanning.Health examination patients were grouped randomly.The single-number group was perfomed low-dose scanning and the even-number group was perfomed routine-dose scanning. 7.5 mm,5mm low-dose and 5mm conventional-dose images were reconstructed indivisually.All other patients were performed low-dose plain whole lung scanning. Additional thin axis scans with low- and conventional-dose were obtainned at the level of the lesion when nodule or mass was detected. Conventional-dose scans were performed after administration of intravenous contrast materials in patients detected nodule or mass firstly. 5mm of the two dose and 7.5mm of the low-dose images were reconstructed using standard resolution.And VR images of the two dose were reconstructed using standard and high resolution separately. In suspected diffuse disease cases, additional high resolution thin axi scans of low- and conventional-dose were performed at the level of typic lesion.Conventional-dose scans were performed after administrations of intravenous contrast materials in some patients .7.5mm of two dose image were reconstructed using standard resolution.Patients with central airway lesions were scanned with two mAs. SSD and VR images were obtained with standard and high resolution algorithm. Seven images of the same region were obtained at setting between 15 and 220mAs in patients undergong CT-guided chest biopsies.172 patients were selected removing the ones cannot hold breath and not including 7 doses images during CT-guided chest biopsies. Image quality was evaluated in health examination patients;the influence on lung disease was valued according to nodule or mass,diffuse lesionand central airway lesion,repeat scans were performed with different mAs in patients undergong CT-guided chest biopsies ,and then the fit dosage was evalued. All images were evaluated by two or more radiologists with certain experience and results were analysed statistically. Statistics analysis was performed in all imaging evaluation results.(l)health examination cases:.The display of bronchi in two dose image was compared.Three levels of aortic arch,tracheal carina and low pulmonary vein were selected ,in order to compare the difference of two dose MSCT in imaging quality of lung and mediastinum window and displaying of normal structures .(2) nodule or mass : Comparing the difference in form,size ..density of nodule or mass of two dose 5mm image,thin image , and 7.5mm low-dose image.The influence on VR image quality of different dose and algorithm. (3 ) diffuse lesion: Comparing the displaying of the lesion kind,range,distribution and character of two dosages standard-resolution images.The difference of two dose high-resolution thin images in lesion character was compared too. (4) central airway lesion : Comparing SSD and VR imaging quality and bronchi manifestion and inspection of central airway lesion of central airway . (5) CT-guided chest biopsie: Comparing the i...
|
PDF Full Text Request