Generation of virtual monoenergetic images at 40 keV of the upper abdomen and image quality evaluation based on generative adversarial networks.

BACKGROUND: Abdominal CT scans are vital for diagnosing abdominal diseases but have limitations in tissue analysis and soft tissue detection. Dual-energy CT (DECT) can improve these issues by offering low keV virtual monoenergetic images (VMI), enhancing lesion detection and tissue characterization. However, its cost limits widespread use. PURPOSE: To develop a model that converts conventional images (CI) into generative virtual monoenergetic images at 40 keV (Gen-VMI40keV) of the upper abdomen CT scan. METHODS: Totally 444 patients who underwent upper abdominal spectral contrast-enhanced CT were enrolled and assigned to the training and validation datasets (7:3). Then, 40-keV portal-vein virtual monoenergetic (VMI40keV) and CI, generated from spectral CT scans, served as target and source images. These images were employed to build and train a CI-VMI40keV model. Indexes such as Mean Absolute Error (MAE), Peak Signal-to-Noise Ratio (PSNR), and Structural Similarity (SSIM) were utilized to determine the best generator mode. An additional 198 cases were divided into three test groups, including Group 1 (58 cases with visible abnormalities), Group 2 (40 cases with hepatocellular carcinoma [HCC]) and Group 3 (100 cases from a publicly available HCC dataset). Both subjective and objective evaluations were performed. Comparisons, correlation analyses and Bland-Altman plot analyses were performed. RESULTS: The 192nd iteration produced the best generator mode (lower MAE and highest PSNR and SSIM). In the Test groups (1 and 2), both VMI40keV and Gen-VMI40keV significantly improved CT values, as well as SNR and CNR, for all organs compared to CI. Significant positive correlations for objective indexes were found between Gen-VMI40keV and VMI40keV in various organs and lesions. Bland-Altman analysis showed that the differences between both imaging types mostly fell within the 95% confidence interval. Pearson's and Spearman's correlation coefficients for objective scores between Gen-VMI40keV and VMI40keV in Groups 1 and 2 ranged from 0.645 to 0.980. In Group 3, Gen-VMI40keV yielded significantly higher CT values for HCC (220.5HU vs. 109.1HU) and liver (220.0HU vs. 112.8HU) compared to CI (p < 0.01). The CNR for HCC/liver was also significantly higher in Gen-VMI40keV (2.0 vs. 1.2) than in CI (p < 0.01). Additionally, Gen-VMI40keV was subjectively evaluated to have a higher image quality compared to CI. CONCLUSION: CI-VMI40keV model can generate Gen-VMI40keV from conventional CT scan, closely resembling VMI40keV.

Preliminary application of 3.0 T magnetic resonance chemical exchange saturation transfer imaging in brain metastasis of lung cancer.

BACKGROUND: Lung cancer brain metastases are very common and one of the common causes of treatment failure. We aimed to examine the clinical use of chemical exchange saturation transfer (CEST) technology in the evaluation of brain metastases for lung cancer diagnosis and prognosis. METHODS: We included26 cases of lung cancer brain metastases, 15 cases of gliomas, and 20 cases with normal tests. The magnetization transfer ratio (MTR;3.5 ppm) image from the GRE-EPI-CEST sequence was analyzed using the ASSET technique and APT technology. The MTR values were measured in the lesion-parenchymal, edema, and non-focus regions, and the MTR image was compared with the conventional MRI. ANOVA and t-test were used for statistical analysis. RESULTS: The lesion-parenchymal, edema, and non-focus areas in the metastatic-tumor-group were red-yellow, yellow-green, and green-blue, and the MTR values were 3.29 ± 1.14%,1.28 ± 0.36%,and 1.26 ± 0.31%, respectively. However, in the glioma-group, the corresponding areas were red, red-yellow, and green-blue, and the MTR values were 6.29 ± 1.58%, 2.87 ± 0.65%, and 1.03 ± 0.30%, respectively. The MTR values of the corresponding areas in the normal-group were 1.07 ± 0.22%,1.04 ± 0.23%, and 1.06 ± 0.24%, respectively. Traditional MR images are in black-white contrast and no metabolic information is displayed. The MTRvalues of the three regions were significantly different among the three groups. The values were also significantly different between the parenchymal and edema areas in the metastatic-tumor-group. There were significant differences in the MTR values between the non-lesion and edema regions, but there was no significant difference between the edema and non-focus areas. In the glioma-group, there were significant differences in the MTR values between the parenchymal and edema areas, between the parenchymal and non-focus areas, and between the edema and non-focus areas. CONCLUSIONS: CEST reflects the protein metabolism; therefore, early diagnosis of brain metastases and assessment of the prognosis can be achieved using molecular imaging.

Retrospective study of BRAFV600E mutation and CT features of papillary thyroid carcinoma.

Objective: This study aimed to examine the correlation between BRAFV600E status and computed tomography (CT) imaging characteristics in papillary thyroid carcinoma (PTC) and determine if suspicious CT imaging features could predict BRAFV600E status. Methods: This retrospective study included patients with pathologically confirmed PTC at the Department of Thyroid Surgery of Zhongshan Hospital, Xiamen University, between July 2020 and June 2022. We compared the clinicopathologic factors and CT findings of nodules with and without the mutation, and the multiple logistical regression test was used to determine independent parameters of the BRAFV600E mutation. Results: This study included 381 patients with PTC, among them, BRAFV600E mutation was detected in 314 patients (82.4%). Multivariate logistic regression analysis showed that gender (OR = 0.542, 95% CI [0.296-0.993], P = 0.047) and shape (OR = 0.510, 95% CI [0.275-0.944], P = 0.032) were associated with BRAFV600E mutation. Conclusions: Compared to BRAFV600E mutation-negative, BRAFV600E-positive PTC lesions were more likely to be found in female patients and were characterized by irregular shape. However, the CT imaging finding is not enough to predict BRAFV600E status, but an indication.

Altered functional brain networks in coronary heart disease: independent component analysis and graph theoretical analysis.

Coronary heart disease (CHD) confers a high risk of cognitive and mental impairments in patients. This study aimed to explore the association of CHD with functional connectivity and topological properties of brain networks. A total of 27 patients with CHD and 44 healthy controls (HCs) participated in this study and underwent a resting-state functional magnetic resonance imaging (rs-fMRI) scan. Intra- and internetwork functional connectivity alterations were explored using independent component analysis in CHD patients. Furthermore, graph theoretical analysis was adopted to assess abnormalities in small-world properties and network efficiency metrics of brain networks. Compared to HCs, CHD patients exhibited increased functional connectivity between the posterior default mode network and posterior visual network, as well as decreased functional connectivity between the left frontoparietal network and auditory network. In terms of graph theoretical analysis, small-world network topology was identified in both CHD patients and HCs. Furthermore, the nodal local efficiency of the left putamen was significantly decreased in CHD patients compared to HCs. This study revealed alterations in brain functional connectivity and topological properties in CHD patients, shedding light on the potential neurological mechanism underlying cognitive and mental impairments in these patients and suggesting unexplored connections between CHD and higher order cognitive processing.

Intrinsic brain abnormalities in chronic rhinosinusitis associated with mood and cognitive function.

Background: Chronic rhinosinusitis (CRS) poses a risk for developing emotional and cognitive disorders. However, the neural evidence for this association is largely unclear. Resting-state functional magnetic resonance imaging (rs-fMRI) analysis can demonstrate abnormal brain activity and functional connectivity and contribute to explaining the potential pathophysiology of CRS-related mood and cognitive alterations. Methods: Chronic rhinosinusitis patients (CRS, n = 26) and gender- and age-matched healthy control subjects (HCs, n = 38) underwent resting-state functional MRI scanning. The amplitude of low-frequency fluctuations (ALFF) was calculated to observe the intrinsic brain activity. The brain region with altered ALFF was further selected as the seed for functional connectivity (FC) analysis. Correlation analysis was performed between the ALFF/FC and clinical parameters in CRS patients. Results: Compared with HCs, CRS patients exhibited significantly increased ALFF in the left orbital superior frontal cortex and reduced connectivity in the right precuneus using the orbital superior frontal cortex as the seed region. The magnitude of the orbital superior frontal cortex increased with inflammation severity. In addition, ALFF values in the orbital superior frontal cortex were positively correlated with the hospital anxiety and depression scale (HADS) scores. The ROC curves of altered brain regions indicated great accuracy in distinguishing between CRS patients and HCs. Conclusion: In this study, patients with CRS showed increased neural activity in the orbital superior frontal cortex, a critical region in emotional regulation, and this region also indicated hypoconnectivity to the precuneus with a central role in modulating cognition. This study provided preliminary insights into the potential neural mechanism related to mood and cognitive dysfunctions in CRS patients.

Clinical application and technique of 64-slice spiral CT subtraction angiography in head and neck.

BACKGROUND: To discuss the technique of 64-slice spiral CT subtraction angiography (64-SCTSA) in head and neck, and evaluate its clinical application. PATIENTS AND METHODS: 84 patients suspected of head-neck vascular diseases were examined with 64-SCTSA. The examination techniques, image quality and clinical application were retrospectively analyzed, and the diagnoses of 64-SCTSA were compared with those of surgery or DSA. RESULTS: Eighty-four subjects were successfully examined with 64-SCTSA, whose scanning and imaging parameters are effective. Image quality was excellent in 51 cases (60.7 %), good in 29 (34.5 %) and acceptable in 4 (4.8 %). In the 84 subjects, 79 cases were found abnormal in blood vessel (58 in head and 21 in neck), of which 57 were confirmed by surgical operation or digital subtraction angiography (DSA). CONCLUSIONS: 64-SCTSA is a feasible technique with satisfactory image quality and has the advantages of showing the lesions of vasculature without shelter from bone. It can improve the diagnostic accuracy in head-neck vascular diseases.

Looking for the Genes Related to Lung Cancer From Nasal Epithelial Cells by Network and Pathway Analysis.

Previous studies have indicated that the airway epithelia of lung cancer-associated injury can extend to the nose and it was associated with abnormal gene expression. The aim of this study was to find the possible lung cancer-related genes from the nasal epithelium as bio-markers for lung cancer detection. WGCNA was performed to calculate the module-trait correlations of lung cancer based on the public microarray dataset, and their data were processed by statistics of RMA and t-test. Four specific modules associated with clinical features of lung cancer were constructed, including blue, brown, yellow, and light blue. Of which blue or brown module showed strong connection to genetic connectivity. From the brown module, it was found that HCK, NCF1, TLR8, EMR3, CSF2RB, and DYSF are the hub genes, and from the blue module, it was found that SPEF2, ANKFN1, HYDIN, DNAH5, C12orf55, and CCDC113 are the pivotal genes corresponding to the grade. These genes can be taken as the bio-markers to develop a noninvasive method of diagnosing early lung cancer.

Aberrant Spontaneous Brain Activity in Coronary Heart Disease Using Fractional Amplitude of Low-Frequency Fluctuations: A Preliminary Resting-State Functional MRI Study.

Objective: This study is aimed at exploring the spontaneous brain activity changes by measuring the fractional amplitude of low-frequency fluctuations (fALFF) and their relationship with clinical characteristics in patients with coronary heart disease (CHD). Methods: Coronary heart disease patients (n = 25) and age, gender, and education level-matched control subjects (controls, n = 35) were included. The grey matter volume (GMV) and fALFF values were calculated to assess the difference in brain structure and function between the two groups, respectively. Correlation analyses between the fALFF values and clinical characteristics were further assessed in CHD patients. In addition, receiver operating characteristic (ROC) curves were conducted to access the diagnostic ability of the fALFF method. Results: There was no significant difference in GMV between the CHD and control groups. Compared with the control group, patients with CHD showed significantly decreased fALFF in the left precentral/postcentral gyrus and increased fALFF in the right inferior cerebellum. Patients with a history of myocardial infarction (MI) showed significantly decreased fALFF values of the right inferior cerebellum than patients without MI. There was no significant correlation between the fALFF values in specific brain regions and disease duration. Furthermore, the ROC curves of abnormal brain regions showed the perfect accuracy of the fALFF value in distinguishing between CHD patients and controls. Conclusion: CHD demonstrated aberrant neural activity in specific brain regions mainly related to sensorimotor networks and pain processing, which may contribute to understanding the underlying neurological mechanism of CHD.

Echocardiography and 64-multislice computed tomography angiography in diagnosing coronary artery fistula.

BACKGROUND/PURPOSES: There are various types of coronary artery fistula (CAF) with complex shapes; therefore, it is important to obtain a correct diagnosis and to understand its relations to the adjacent structures before surgery. This study evaluated echocardiography and 64-multislice computed tomography (64-MSCT) angiography in diagnosing CAF. METHODS: Sixteen patients with CAF, confirmed by surgical operation or digital subtraction angiography, were examined by echocardiography. Five of them were further examined by 64-MSCT angiography for detailed anatomical information before surgery. The imaging data for echocardiography and 64-MSCT angiography were analyzed retrospectively. RESULTS: Among the 16 patients, 12 were correctly diagnosed by echocardiography, of whom five were confirmed by 64-MSCT angiography. Four cases missed diagnosis by echocardiography, and one of these was correctly diagnosed by 64-MSCT. Seventeen fistulae were found, of which, two appeared in one patient. Ten fistulae originated from the left coronary artery and seven from the right. The draining site was the right heart in eight, pulmonary artery in five, left heart in three and aorta in one. CONCLUSION: Echocardiography can act as the routine examination of CAF, and 64-MSCT angiography can provide more detailed anatomical and pathological information for surgery than echocardiography.

Three-dimensional CT study on the anatomy of vertebral artery at atlantoaxial and intracranial segment.

BACKGROUND: The atlantoaxial and intracranial segments of vertebral artery (V(3-4)) are winding around their peripheral structures. Their panorama is not easy to be observed in surgery. CT angiography (CTA) shows some advantages in this aspect. So, the aim of this study is to reveal the three-dimensional (3D) anatomy related to V(3-4) and prepare ground for clinical diagnosis and treatment. METHODS: Ninety-eight cases without the pathologies of V(3-4) were selected from the head-neck CTA examination. All the 3D images were formed with multiplanar reconstruction, volume rendering and volume rendering together with separating, fusing, opacifying and false-coloring. On the 3D images, the courses and branch of V(3-4) were observed and measured, as well as their peripheral venous vascular plexus (VVP). RESULTS: V(3-4) with typical five curves was found in 85 cases and with variations in 13. The left V(3-4) is larger than right (P < 0.05). The branch shown on the 3D image is the posterior inferior cerebellar artery at V(4), at most two on either side. VVP are at the back of the atlantoaxial joints and around the V(3), each on either side. There is no significant difference in size and shape between left and right (P > 0.05). CONCLUSIONS: The anatomy and variations of V(3-4) can be clearly and directly shown by 3DCTA. The understanding of vertebral artery and bony structures around there can provide anatomic basis for surgery and radiological diagnosis.

Imaging anatomy and variation of vertebral artery and bone structure at craniocervical junction.

The objective of this article is to display the vertebral artery and bone structure at the craniocervical junction (CJVA and C(0-1-2)) with three-dimensional CT angiography (3DCTA) and identify their anatomic features and variations. Eighty-eight subjects without pathology of vertebral artery (VA) and C(0-1-2) were selected from head-neck CTA examination. 3D images were formed with volume rendering (VR) and multiplanar reconstruction (MPR). On the 3D images, CJVA and C(0-1-2) were measured, and their variations were observed. CJVA goes along C(0-1-2) with five curves, of which three curves are visibly away from C(0-1-2), one is 0.0-8.3 mm away at the second curve with 0.0-11.2 mm in width, another is 0.0-9.2 mm away at the fourth with 2.8-14.8 mm and the other is 0.0-6.2 mm away at the fifth. Statistical comparisons show that there is no significant difference in the measurements between left and right, and that the curves become smaller and farther away from C(0-1-2) with the increase of age. CJVA is not equal in size, with the biggest in the fourth curve and the smallest in the fifth. Statistical comparison shows the left CJVA is larger than the right in the fifth curve. Variations were found on CJVA in 16 cases and on C(1) in 12 cases. The anatomy and variations of CJVA and C(0-1-2) are complicated. It is of vital significance to identify their anatomic features in clinical practice.

Clinical significance of articulating facet displacement of lateral atlantoaxial joint on 3D CT in diagnosing atlantoaxial subluxation.

BACKGROUND/PURPOSE: To improve the recognition of articulating facet displacement of lateral atlantoaxial joint (AFDLAJ), and to evaluate the significance of AFDLAJ in diagnosing atlantoaxial subluxation. METHODS: The three-dimensional computed tomography (3D CT) imaging findings of 54 patients with atlantoaxial subluxation were retrospectively analyzed, and the imaging features of AFDLAJ were discussed. All the patients were examined in neutral position, and 25 in an additional rotary position. 3D images of the atlantoaxial joints were obtained by surface shade display and volume rendering. The diagnostic results of 3D CT, routine CT and X-ray were compared. RESULTS: All the 54 patients with atlantoaxial subluxation were correctly diagnosed by 3D CT with no suspicious or missed diagnoses, including 38 cases of rotatory subluxation, 11 of anterior subluxation and five of posterior subluxation. AFDLAJ was found in all the 54 patients in neutral position, with the extent of subluxation between 2.0 mm and 9.0 mm. Among the 25 cases in rotary position, rotational fixation was found in 10 cases and rotational asymmetry in 15. The diagnostic accuracy of 3D CT was higher than that of X-ray or routine CT. CONCLUSION: Once AFDLAJ appears in neutral position and rotational fixation or asymmetry in rotary position, atlantoaxial subluxation can be ascertained, as well as the type and extent of subluxation, and fake subluxation due to the heads rotation or normal lateralized odontoid can be excluded. AFDLAJ is a vital direct sign in diagnosing atlantoaxial subluxation.

Clinical value of CT three-dimensional imaging in diagnosing gastrointestinal tract diseases.

AIM: To discuss the clinical value of CT three-dimensional (3-D) imaging in diagnosing gastrointestinal tract diseases. METHODS: Three-D imaging findings of 52 patients were retrospectively analyzed. Three-D imaging methods included shaded surface display (SSD), volume rendering (VR), virtual endoscopy (VE) and multiplanar reformatting (MPR). The diagnosis results of CT 3-D were evaluated by comparison with those of endoscopy and/or surgical finding. RESULTS: Fifty-two patients with gastrointestinal tract diseases were diagnosed by CT 3-D imaging, of whom 50 cases were correctly diagnosed and 2 were misdiagnosed. There were 33 cases of gastric diseases (27 with carcinoma, 5 with peptic ulcer and 1 with leiomyoma) and 19 large intestinal diseases (10 with colon carcinoma, 2 with carcinoma of the rectum, 5 with colon polypus and 2 with tuberculosis of the ileocecal junction). Twenty-two cases with prominent lesions (9 with subsequent hollow lesions), 20 with stenosis of cavity (8 with concomitant prominent lesions) and 10 with hollow lesions (5 with concomitant prominent lesions) were shown in 3-D images. The minimal lesion shown was 1.0 cm x 0.8 cm x 0.5 cm. CONCLUSION: CT 3-D imaging, a non-invasive examination without pain, can display clearly and directly the lesions of gastrointestinal tract with accurate location and high diagnosis accuracy. It is an important complementary technique to endoscopy.

Modeling of internal carotid artery aneurysm and blood flow simulation.

BACKGROUND: The rupture of aneurysm is quite common in the clinics, and is hazardous to patients. Its occurrence is considered to be related to the hemodynamic abnormalities. OBJECTIVE: To construct the model of internal carotid artery aneurysm (ICA-A), and have a simulation of blood flow. METHODS: Based on the CTA data from spiral CT scan, the ICA-A model was constructed, and the types of blood flow, wall shear stress (WSS), Von Mises stress (VMS) and pressure were simulated and calculated. RESULTS: ICA-A model has been built and shape is the same morphology as CT 3D-image. In the whole cardiac cycle, the blood flow of aneurysm body is swirl, its velocity is slower than that of aneurysm neck; the maximum deformation, wall shear stress, pressure and von mises stress of aneurysm wall is at the neck, the minimum is at the top. The highest value appeared at 0.52 s in the cardiac cycle of 0.74 s, the lowest is at 0.21 s. CONCLUSIONS: It is effective and practical to construct the model of ICA-A base on CTA data. Blood flow simulation of ICA-A will provide new basis for the study on the occurrence and development of aneurysm.

Application of CT 3D reconstruction in diagnosing atlantoaxial subluxation.

OBJECTIVE: To evaluate and compare the diagnostic value in atlantoaxial subluxation by CT three-dimensional (3D) reconstruction. METHODS: 3D reconstruction findings of 41 patients with atlantoaxial subluxation were retrospectively analyzed, and comparisons were made among images of transverse section, multiplanar reformorting (MPR), surface shade display (SSD), maximum intensity project (MIP), and volume rendering (VR). RESULTS: Of 41 patients with atlantoaxial subluxation, 31 belonged to rotary dislocation, 5 antedislocation, and 5 hind dislocation. All the cases showed the dislocated joint panel of atlantoaxial articulation. Fifteen cases showed deviation of the odontoid process and 8 cases widened distance between the dens and anterior arch of the atlas. The dislocated joint panel of atlantoaxial articulation was more clearly seen with SSD-3D imaging than any other methods. CONCLUSIONS: Atlantoaxial subluxation can well be diagnosed by CT 3D reconstruction, in which SSD-3D imaging is optimal.

Magnetic resonance imaging of disc space infection revisited: temporal changes.

BACKGROUND: Magnetic resonance imaging (MRI) has advantages in showing pathologic changes of disc space infection, which is important in clinical treatment. The purpose of this study was to describe the MRI findings of disc space infections in relation to chronicity. METHODS: MRI of 60 patients from January 1, 2002 to April 30, 2012 in Ottawa Hospital were retrospectively evaluated by two radiologists blindly. All patients had histological confirmation, with 55 having microbiological confirmation as well. These patients were divided into acute (n = 18), subacute (n = 21) and chronic (n = 21) based on histological findings. The following potential signs of MRI finding were assessed: marrow edema, endplate erosions, disk fluid and height change, paraspinal mass, epidural collection, facet fluid and enhancement in the marrow, disc, paraspinal mass, and epidural involvement. Statistical analysis consisted of t- or F-tests and chi-square test. RESULTS: In the 60 patients, 83 infected discs (single disc in 45 patients, 2-4 discs in 15 patients) were found, including 22 discs in the acute group, 30 discs in the subacute group, and 31 discs in the chronic group. There was a significant difference in the extent of marrow edema between the acute, subacute and chronic groups (P < 0.05), with a gradually increasing extent from acute to chronic. The extent of endplate erosions increased with chronicity, but was not statistically significant. There were significant differences in the disc fluid, epidural collection, and disc enhancement among the acute, subacute and chronic groups, as well as the facet fluid between acute and chronic groups (P < 0.05). There were no significant differences in the present probability of disc height loss, paraspinal mass, and marrow enhancement among the three groups (P > 0.05). CONCLUSIONS: From acute to chronic infections, the extent of marrow edema and endplate erosions appeared to gradually increase. Epidural collections and facet fluid are most frequently found in the acute group, while disc fluid and disc enhancement are more common in the chronic patients.

Three-dimensional CT angiography study on the relations between the vertebral artery and atlantoaxial joint.

BACKGROUND: The vertebral artery (VA) and atlantoaxial joint (AAJ), with complicated structures, are located in the depths of the head-neck boundary area, the regional anatomy of which cannot be shown globally and directly. This study aims to evaluate three-dimensional CT angiography (3DCTA) in displaying the AAJ, atlantoaxial segment of the vertebral artery (ASVA) and the identification of their interrelations. METHODS: Sixty-eight subjects without pathology of the ASVA and AAJ were selected from head-neck CTA examination. All the 3D images were formed with volume rendering (VR) together with techniques of separating, fusing, opacifying and false-coloring (SFOF). On the 3D images, the ASVA and AAJ were observed, and their interrelations were measured. RESULTS: All the 3DCTA images were of high quality and up to our requirements. They could clearly and directly show the ASVA, ascending along the AAJ. There were 5 curves in the course of the ASVA, of which 2 curves were away from the atlantoaxial joint, one in the 2nd curve of 0.0 mm - 5.4 mm, the other in the 4th of 2.6 mm - 9.2 mm. There was no significant difference in the measurements between left and right (P > 0.05). The curved parts of the ASVA slightly expanded, with the biggest diameter of 5.6 mm in the 4th curve. Statistical comparison shows that the left ASVA is larger than the right (P < 0.05). Variations of the ASVA were found in 8 cases and of the AAJ in 12. CONCLUSIONS: 3DCTA can globally and directly demonstrate the structures of the AAJ, ASVA and their interrelations. The 3D imaging data make up and enrich the research contents of regional anatomy and lay the foundation for related study and applications.

Three-dimensional CT study on normal anatomical features of atlanto-axial joints.

It has long been a research hotspot to diagnose atlanto-axial disorder by observing the shape and motions of atlanto-axial joints. The basis for correlative studies is to ascertain the normal anatomic features of atlanto-axial joints. In our study, 33 normal subjects were examined for atlanto-axial joints, by three-dimensional CT (3D-CT) in functional positions (neutral, left and right rotary position). The contraposition between superior and inferior articular facets of lateral atlanto-axial joints (AFLAJ), including its shape and type, the width of rotational facets displacement (RFD), head's rotational angle (HRA) and rotational angle at C(1-2) (RAC(1-2)) were observed and measured on 3D-CT images. In neutral position, a complete contraposition of AFLAJ was found in 25 subjects as well as a basic contraposition in 8. In rotary position, the width of RFD was between 6.16 and 8.68 mm, the angle of HRA was between 30.2 degrees and 45.8 degrees , and RAC(1-2) between 26.7 degrees and 38.9 degrees . There is no significant difference in RFD, HRA or RAC(1-2) (P > 0.05) in between levorotatory and dextrogyrate orientation, and there is a positive correlation between RFD and RAC(1-2) (r = 0.5078, P < 0.05). Our study results show that the contraposition of AFLAJ can be clearly displayed by 3D-CT, and complete or basic contraposition in neutral position and symmetry RFD, HRA and RAC(1-2) in rotary position, are the normal anatomic features of atlanto-axial joints.