PurposeTo evaluate the effect of tube current on the pseudo-enhancement of renal cyst by simulating the phantom model of simple renal cyst.Materials and Methods 10% glucose and iodine solution with a certain concentration was used to simulate the renal parenchymal background concentration in plain scan, moderate enhancement and maximum enhancement respectively. The diameters of the cysts were 6 mm, 10 mm and 15 mm, respectively, and the cysts were divided into three groups according to different tube current: 119 mAs (group A), 178 mAs (group B) and 297 mAs (group C) while the tube voltage were all 120 kV. Whether pseudo-enhancement exists in cyst under different conditions was determined using an increase of CT value of 10 HU as the critical value. Results In group A, there was pseudo enhancement at the 240 HU background, and it was most significant with the diameter of 6 mm, which was 21 HU. In group B, pseudo-enhancement occurred in cysts with diameter of both 10 mm and 6 mm under the background of 180 HU and 240 HU, moreover, the biggest difference was 20.4 HU and it occurred in cyst with diameter of 6 mm under the background of 240 HU. In group C, pseudo-enhancement only occurred in cyst with diameter of 6 mm under the condition of 125 HU and 240 HU background concentration. Background concentration (F=17.587, P<0.01) and cyst diameter (F=4.214,P<0.05) had greater impact on cyst pseudo-enhancement, the higher the background concentration and smaller the diameter, more significantly the pseudo-enhancement would occur. With the increase of the tube current, the CT volume dose index increased, and the pseudo enhancement value was smaller, but there was no obvious regularity of pseudo-enhancement occurrence rate in cysts with different background concentration and diameter in each group.Conclusion The increase of tube current cannot completely eliminate cyst pseudo-enhancement. High background concentration and small diameter cyst are important factors in pseudo-enhancement. However, increasing the tube current can reduce the probability of occurrence of pseudo-enhancement to some extent. For those with heavier body weight, it might be necessary to increase the tube current to improve image quality and reduce the occurrence of renal cyst pseudo-enhancement.

PurposeSmart neuro attenuation correlation (SNAC) is a new method of calculated attention correction. This paper aims to evaluate the impact of SNAC on the quality and standardized uptake value of brain imaging with PET/CT.Materials and Methods Fifty-eight patients who underwent systematic scan with18F-FDG PET/CT were analyzed retrospectively. CT attenuation correlation (CTAC) and SNAC brain PET images were reconstructed respectively. All images were analyzed by visual assessment and Scenium software and the results of the two methods were compared with regard to image contrast, homogeneity and mean SUV at different cerebral regions. Moreover, the correlation of the mean SUV of the two methods was further analyzed.Results There was no significant visual difference of contrast and uniformity between SNAC and CTAC. The Scenium analysis shows that the contrast of SNAC images were slightly higher than that of CTAC, but the difference were not statistically significant (4.19±1.11vs. 4.08±1.03,t=0.764,P>0.05). The uniformity of SNAC images were slightly lower than that of CTAC (1.00vs. 0.83). The mean SUV at various brain regions measured by SNAC was greater than that by CTAC, but both were significantly correlated (r=0.978,P<0.01), and the linear regression analysis also demonstrated that the results were consistent (R2=0.959). Compared with that measured by CTAC, the average percentage difference of SUV measured by SNAC was 8.45±4.71, but it varied greatly at 10 brain regions (-8.56-27.93). The analysis of variance presented significant differences in the average percentage difference of SUV at different brain regions (F=119.084,P<0.01), while the average percentage difference at the outer slices was greater than that at the central slices. Conclusion No significant difference exists in image quality between SNAC and CTAC. Although the mean SUV at different brain regions measured by SNAC may increase by various degrees, it is significantly associated with the results measured by CTAC. Moreover, SNAC simplifies the process of examination and reduces radiation dose, which is beneficial to patients as a qualitative method.

To improve the precision of image registration based on corner detection, a relative position function between multiple points to determine matching points accurately. First the corners in images are detected using Harris detector, and clustering method is used to eliminate most wrong matches after coarse screening. Then the proposed relative position function is used as a criterion of precise matching. Finally the image registration process is accomplished by affine transformation. Results show that the proposed algorithm is more effective and accurate than conventional registration algorithm.

As a new neuroimaging method, functional magnetic resonance (fMRI) with its importance of data processing has been widely recognized by neurology and cognitive psychology. Focusing on the realignment section in fMRI image preprocessing, this paper comprehensively describes the registration principle of SPM, an internationally-known software package which is specially designed for cerebral function imaging. An improved registration method is presented which effectively increases the accuracy. In addition, choosing the ratio of SSD and NMI as the registration measure can compensate for the limitation of using single measurement, which improves the robustness and reliability of the registration process. Experimental results prove the feasibility of this method.

Purpose To evaluate ultrasonography in diagnosis of high recurrence risk gastrointestinal stromal tumors (GIST) by retrospective studying the ultrasound (US) imaging features of GITS. Materials and Methods US features of 72 GIST cases confirmed histopathologically were retrospectively studied. The tumor size, shape, boundary, echogenicity and blood flow of GITS were observed and compared with the results of histopathology. Results Of all the 72 tumors, 34 were originated in the stomach, 14 in the intestine, 2 in the colon, 8 in the rectum, 9 in the mesentery, 1 in the posterior peritoneum, 1 in the omentum and 3 huge masses of non definite origin. There were 7 cases with very low recurrence risk, 14 cases with low risk, 11 cases with intermediate risk and 40 cases with high risk. High recurrence risk group showed no statistical difference in heterogeneous hypoechoes and blood flow (P>0.05), but showed significantly higher rates in following US features:size larger than 5.0 cm, irregular shape, obscure boundary and cyst-solid echogenecity (P<0.001), which showed the sensitivity of 95.0% (32/40), 72.5% (29/40), 25.0% (10/40), and 55.0% (22/40), respectively; and the specificity of 59.4% (19/32), 81.3% (26/32), 90.6% (29/32), and 87.5% (28/32), respectively. Conclusion US can serve as a mean of screening GIST. The recurrence risk can be evaluated based on the tumor size, shape, boundary and echogenecity to guide clinical decisions and prognosis evaluation.

Purpose To detect the distribution of cerebral microbleeds (CMB) in patients with hypertension and evaluate its related risk factors in order to reduce long-term risk of cerebral hemorrhage in large areas. Materials and Methods A consecutive 110 patients of hypertension and 50 patients of non-hypertension in the departments of cardiovascular medicine and neurology were enrolled. All the patients underwent T2 star weighted angiography (SWAN) sequence scan of head. The location and quantity of CMB and other related information of patients were recorded. The distribution of CMB in patients with hypertension and correlation between CMB and age, sex, level of hypertension, duration of time, hemoglobin, platelets, smoking, diabetes, hyperlipidemia were also analyzed. Results A total of 472 CMB were detected in the hypertension group, of which 212 CMB (44.9%) were found in deep brain, 149 (31.6%) were in cortical and subcortical region, 111 (23.5%) under the tentorium. The highest distribution of CMB was in thalamus (98, 20.8%), followed by basal ganglia (78, 16.5%), temporal lobe (64, 13.6%) and brainstem (62, 13.1%). The univariate analysis showed that CMB group had significantly higher rate of hypertension and diabetes than that without CMB and the average age in CMB group was also higher (P<0.05). The results of multivariate analysis showed that age and hypertension were independent risk factors for CMB. In hypertension group, there was statistically significant difference in the incidence of CMB between patients aged 45 and older and those aged under 45 (P<0.05);the differences were significant between the patients with hypertension duration time less than 5 years, those with hypertension duration time 5 to 10 years and those over 10 years (P<0.05);the differences also existed between the patients with hypertension at class I and those patients with hypertension at class II and III (P<0.05). The quantity of CMB in patients with hypertension was correlated with duration time (P<0.05), but not correlated with age and the severity of hypertension (P>0.05). Conclusion Hypertension and age are independent risk factors for CMB. Patients aged 45 and older, with more than 5 years duration of hypertension, or with hypertension at class II and III, should be paid more attention in clinic. If necessary, magnetic resonance examination is suggested to be used, in order to reduce long-term risk of cerebral hemorrhage.

Purpose Central nervous system (CNS) hemangiopericytoma (HPC) is rare in clinic and prone to misdiagnosis. This paper aims to improve the diagnostic accuracy of CNS HPC by analyzing the MRI and CT features. Materials and Methods CT and MRI appearances and pathologic features of 14 cases with surgery and pathology proved CNS HPC were analyzed retrospectively. Results There were intracranial and intraspinal lesions in 12 and 2 cases respectively. 5 cases were lobular, 4 cases irregular, and 5 cases were round or oval in shapes. On CT scan, 2 intracranial lesions showed slight hyperdensity and were avidly enhanced following contrast injection. On T1WI, 11 cases showed isointensity compared with brain white matter;on T2WI, 10 cases showed isointensity compared with brain gray matter. Marked heterogeneous enhancement was shown in 7 cases. Necrosis and cystic changes were seen in 6 cases. Flow-void sign was seen in 9 cases;9 cases were attached to meninges through narrow base. Dural tail sign was observed in 4 cases. Bone erosion was seen in 4 cases. In 5 cases with DWI scan, isointensity was shown in 4 cases and slight hyperintensity in 1 case. The density and signals in 2 cervical spine lesions were uniform with homogenous enhancement;expansive bone swelling in 1 case. Conclusion CNS HPC shows hyperdensity on CT. They present equal signal compared with white matter on T1WI and equal signal compared with grey matter on T2WI, with some void signal of vessel, and isointense on diffusion weighted images. Tumor invades adjacent skull with rare dural tail sign.

Purpose To evaluate the left ventricular regional diastolic function in coronary heart disease (CHD) patients without regional wall motion abnormality by real-time three-dimensional speckle tracking imaging (RT3D-STI) to investigate the value of RT3D-STI in the diagnosis of early CHD. Materials and Methods 140 CHD patients with 420 coronary artery main branches were enrolled and divided into 4 groups according to the results of coronary angiography (CAG): normal group (101 coronary artery branches without stenosis), mild stenosis group (112 coronary artery branches with stenosis<50%), moderate stenosis group (95 coronary artery branches with stenosis 50%-75%) and sever stenosis group (112 coronary artery branches with stenosis>75%). Three dimensional full volume images were collected through the chest, and the corresponding strain imaging diastolic index (SI-DI) of each direction was calculated, their value for the diagnosis of coronary artery disease was analyzed. Results The longitudinal, area and radial SI-DI of mild coronary artery stenosis group were lower than those of normal group (P<0.05);the longitudinal, area, radial and circumferential SI-DI of moderate coronary artery stenosis group were lower than normal group (P<0.05) and the area, longitudinal and circumferential SI-DI were lower than those of the mild stenosis group (P<0.05);the longitudinal, area, radial and circumferential SI-DI were all lower than those of normal and mild stenosis group (P<0.05), and the area, longitudinal and radial SI-DI were all lower than the moderate stenosis group (P<0.05). ROC curve showed that the sensitivity of longitudinal SI-DI (84.0%) was highest, while the specificity of area SI-DI (78.9%) was the highest. Conclusion RT3D-STI has important significance for early detection and diagnosis of CHD, regional diastolic function decrease of the coronary artery supply area occurs earlier than systolic function reduction, and diastolic function is more sensitive for myocardial ischemia, as a result, SI-DI is able to reflect the stenosis degree of coronary artery in a certain extent.

PurposePifrrmann scoring based on T2WI can only evaluate intervertebral disc qualitatively and is easily affected by the surrounding environment and imaging parameters. The present study attempted to make a quantificational study on lumbar intervertebral disc degeneration by using MR T2 mapping sequence so as to improve its diagnosis.Materials and Methods Sagittal T1FSE, sagittal and axial T2FSE, sagittal T2 mapping sequence were performed on 265 lumbar intervertebral discs from 53 subjects. The MR imaging was analyzed and all the discs were classified according to Pifrrmann scoring. T2 relaxation time of the discs was calculated and statistical analysis was conducted on its correlation.Results Among the 265 discs, 5 (1.9%) were scored as Pfirrmann I, 153 (57.7%) were scored as Pfirrmann II, 86 (32.3%) were scored as Pfirrmann III, 20 (7.5%) were scored as Pfirrmann IV, 1 (0.38%) were scored as Pifrrmann V. The average anterior annulus T2 values showed no difference between every Pfirrmann grade (P>0.05), while the difference of average posterior annulus T2 values was significant between groups (P<0.05). The relaxation time of anterior annulus was signiifcantly shorter than that of posterior annulus in the discs of Pifrrmann II-IV, whilst the reverse occurred in the discs of Pifrrmann I (P<0.05). The differences of the relaxation time of nucleus pulposus T2 values were signiifcant between groups of Pifrrmann grade I to IV (P<0.05). The T2 relaxation time of each partition of nucleus pulposus (ROI2/ROI3, ROI3/ROI4, ROI2/ROI4) was signiifcantly correlated (r=0.86, 0.76 and 0.63,P<0.05), the T2 relaxation time of anterior annulus and posterior annulus had no correlation (r=0.09, P<0.05), and the nucleus pulposus T2 values and Pfirrmann grade were negatively correlated (r=-0.78,P<0.05).Conclusion MR T2 mapping can quantitatively evaluate the T2 relaxation time of lumbar intervertebral discs, and is signiifcantly correlated with Pifrrmann grades.

PurposeTo investigate the physical characteristics of the lumbar bone marrow fat content by analyzing the correlation of the lumbar bone marrow fat content with age, gender, body mass index (BMI) and waist circumference. It may be helpful to deepen the understanding the occurrence regularity of osteoporosis. Materials and Methods A total of 144 subjects were recruited including both healthy volunteers and the patients with chronic low back pain. The height, weight and waist circumference were measured, and the body mass index was calculated. All the subjects took spectroscopy sequence at the third lumber vertebra with single-voxel point resolved spectroscopy (PRESS) method. Lipid (1.3 ppm) to water (4.67 ppm) ratio (LWR) and lipid fractions (FF%) were measured. LWR and FF% of L3 were compared among the patients with different gender, age, BMI and waist circumference. The correlation of LWR and FF% of L3 and age were analyzed.Results The LWR and FF% of L3 showed no signiifcant difference between the male and female (t=-0.267 and-0.993,P>0.05). There was statistical difference of LWR and FF% among the different age groups (F=3.723 and 5.478,P<0.05). LWR and FF% of female in 61-70 year-old group showed signiifcant higher than that in 20-30, 31-40, 41-50 and 51-60 year-old group (P<0.05). FF% of L3 in 20-30 year-old female group showed signiifcant lower than that in >70 year-old group (P<0.05). LWR of L3 for both male and female in 60-70 year-old group also showed signiifcant higher than that in 20-30, 31-40, 41-50 and 51-60 year-old group (P<0.05). FF% for both male and female in 20-30 year-old group showed signiifcant lower than that in 31-40, 41-50, 51-60, 61-70 and>70 year-old group (P<0.05). FF% of 61-70 year-old group was signiifcant different from that in 31-40, 41-50, 51-60 year-old group (P<0.05). The LWR and FF% of L3 showed no signiifcant difference between the different BMI groups and waist circumference groups (P>0.05). Age was positive correlated with FF% of L3 (r=0.321,P<0.05).Conclusion The lumbar bone marrow fat content is correlated with age, but is not correlated with gender, BMI and waist circumference.