Automatic detection of osteoporotic vertebral fractures in routine thoracic and abdominal MDCT

Objectives

To develop a prototype algorithm for automatic spine segmentation in MDCT images and use it to automatically detect osteoporotic vertebral fractures.

Methods

Cross-sectional routine thoracic and abdominal MDCT images of 71 patients including 8 males and 9 females with 25 osteoporotic vertebral fractures and longitudinal MDCT images of 9 patients with 18 incidental fractures in the follow-up MDCT were retrospectively selected. The spine segmentation algorithm localised and identified the vertebrae T5-L5. Each vertebra was automatically segmented by using corresponding vertebra surface shape models that were adapted to the original images. Anterior, middle, and posterior height of each vertebra was automatically determined; the anterior-posterior ratio (APR) and middle-posterior ratio (MPR) were computed. As the gold standard, radiologists graded vertebral fractures from T5 to L5 according to the Genant classification in consensus.

Results

Using ROC analysis to differentiate vertebrae without versus with prevalent fracture, AUC values of 0.84 and 0.83 were obtained for APR and MPR, respectively (p?<?0.001). Longitudinal changes in APR and MPR were significantly different between vertebrae without versus with incidental fracture (ΔAPR: -8.5 %?±?8.6 % versus -1.6 %?±?4.2 %, p?=?0.002; ΔMPR: -11.4 %?±?7.7 % versus -1.2 %?±?1.6 %, p?<?0.001).

Conclusions

This prototype algorithm may support radiologists in reporting currently underdiagnosed osteoporotic vertebral fractures so that appropriate therapy can be initiated.

Key points

? This spine segmentation algorithm automatically localised, identified, and segmented the vertebrae in MDCT images. ? Osteoporotic vertebral fractures could be automatically detected using this prototype algorithm. ? The prototype algorithm helps radiologists to report underdiagnosed osteoporotic vertebral fractures.     

Incidental vertebral fractures on multidetector CT images of the chest: prevalence and recognition

AIM: To investigate the prevalence, demographics, fracture site, and the rate of vertebral fracture recognition by radiologists on multidetector computed tomography (MDCT) images of the chest. METHOD: The images of 200 consecutive patients who underwent a MDCT examination of the chest over a 4-month period were reviewed. The thoracic spine, viewed using bone windows in sagittal reformats, was reviewed in consensus by three radiologists. Vertebral fractures were assessed using a validated semi-quantitative method. RESULTS: The mean age was 61 years (range 18-92 years); 48% were female. There were 70 (35%) fractures, of which 51 (73%) were mild grade 1 fractures, 13 (19%) moderate grade 2 fractures, and six (9%) severe grade 3 fractures. Fractures commonly affected patients above the age of 50. The most common site was in the lower thoracic region (53%). The overall recognition rate on the radiologists' reports was 6 (9%). CONCLUSIONS: One in three patients who underwent MDCT of the chest had vertebral fractures. There is significant underreporting of these fractures, and the importance of fracture identification should be emphasized to avoid under-diagnosis.     

Volume-rendered multidetector CT angiography: noninvasive follow-up of patients treated with renal artery stents

OBJECTIVE: The purpose of our study was to evaluate the role of multidetector CT (MDCT) angiography with volume rendering for estimating the patency of renal artery stents. SUBJECTS AND METHODS: In 16 patients, 16 renal artery stents were evaluated with MDCT renal angiography and digital subtraction angiography (DSA). CT data were evaluated using multiplanar volume reformations and the volume-rendering algorithm with three different volume-rendered parameter settings (low-to-high, high-to-low, and high-low-high opacity transfer functions: VR(LH), VR(HL), and VR(VE), respectively). Targeted images of each stent were rendered in paraaxial and paracoronal planes and were interactively interpreted. The overall restenosis severity was measured on postprocessed paraaxial and paracoronal images and compared with that obtained on DSA using linear regression analysis. Image quality and lumen delineation on rendered images were also compared using Wilcoxon's signed rank test. RESULTS: Eight restenoses were identified on DSA. Correlations between restenosis severity measured with DSA and those measured with MDCT were significant (p < 0.001). Volume rendering with VR(HL) allowed the best correlation with DSA (reviewer 1, r(2) = 0.86; reviewer 2, r(2) = 0.94) and was significantly better than multiplanar volume reformations (p = 0.028). Overall image quality was high with all rendering techniques and with no significant differences (p > 0.59, for all comparisons). Stent lumen was well delineated with volume-rendering modalities; however, VR(HL) was significantly better than VR(LH) (p = 0.033). CONCLUSION: Volume-rendered MDCT angiography enabled high-quality three-dimensional reproducible evaluation of the patency of implanted renal artery stents. Volume rendering with VR(HL) achieved the best performance.     

螺旋 CT 容积扫描方法诊断胸廓骨及肋骨骨折的价值探讨

目的：探讨螺旋CT容积扫描诊断胸廓骨骨折的临床价值。方法笔者回顾性分析2011年1月～2014年6月拟诊断为胸廓骨及肋骨骨折患者80例的临床资料,男性49例,女性31例;年龄22～76岁,平均（40．2±2．3）岁。均具有完整X线片、3D图像和CT轴位扫描图像资料,并对X线、3D图像和CT轴位扫描图像的诊断结果进行对比分析。结果排除可疑骨折,以CT轴位扫描图像作为金标准,X线诊断的灵敏度为61．54％,特异度为66．67％;3D容积重建（ VR）诊断的灵敏度为98．59％,特异度为87．50％。结论螺旋CT可快速确诊胸廓骨及肋骨骨折,容积扫描中的容积再现法（ VR）、最大密度投影法（ MIP）和多平面重组法（ MPR）技术能较好显示细微骨折,在解剖空间结构上有较强优势。     

Overcoming population differences for dental age estimation in adults through pulp/tooth volume calculations: a pilot study

ABSTRACT

The aim of this pilot study is to explore the possibility of developing a method for dental age estimation in adults, regardless of their nationality or ethnic background, by reconstructing only a fraction of the tooth, generating linear regression models and an equation for age estimation. Eighty-one anonymized cone beam computed tomography images obtained from two different population groups were used. Only sex and age information was known. One group had a Latin-American background (Colombian individuals aged 23 to 71 years) and the other had an Asian background (Malaysian individuals aged 15 to 58 years) The analysed tooth was the maxillary canine, on which was done automatic volume reconstruction of the cervical third of root and root canal. Sample analysis showed that the ages were unequally distributed in the two groups, but by combining them a more equal age distribution was obtained. The correlation coefficient between pulp/pulp+tooth volume ratio increased when data from individuals of both populations were included in the same statistical analysis (R ² = 0.42). It has been established that methods for age estimation must be population specific. This study presents an analysis including data from individuals that are ethnically different and geographically separated, obtaining promising results.     

正常儿童椎体骨髓转换过程中磁共振信号强度的变化

目的:分析椎体骨髓磁共振T1WI信号强度比值(SIR)与年龄、性别的关系,探讨正常儿童椎体骨髓转换的发生规律.方法:回顾性分析105例正常儿童的脊柱磁共振T1加权序列图像,同时选择血液系统疾病患儿共32例作为病例组对照研究.采用GE 0.2T Profile Gold永磁型开放式磁共振扫描仪行脊柱矢状面SE T1WI扫描.测定椎体磁共振SIR,并对所获得的数据与年龄、性别的关系及正常组和病例组间的比较进行统计学处理.结果:椎体SIR值与年龄变化的关系研究表明,颈椎、腰椎骨髓SIR值与年龄呈正相关,统计学具有显著性意义(P＜0.01),而胸椎骨髓SIR值则与年龄无显著相关性(P=0.06);无论是颈椎、胸椎还是腰椎的SIR值与性别均无显著相关性(P＞0.05);病例组患儿椎体T1信号强度较正常组儿童明显减低,各年龄组病例与正常组间的SIR值差异均具有显著性意义(P＜0.01).结论:儿童年龄段(0～17岁)颈椎和腰椎骨髓转换发生较早,5岁后的骨髓信号较前发生明显增高,而且血液系统疾病患者椎体骨髓T1信号较正常显著减低.因此,利用SIR定量测定法对弥漫性骨髓疾病具有更高的敏感性.     

Imaging findings of hepatic focal nodular hyperplasia in men and women: are they really different?

Purpose

This study was undertaken to compare the imaging findings of focal nodular hyperplasia (FNH) in men and women, as seen on multidetector computed tomography (MDCT), magnetic resonance imaging (MRI) and contrast-enhanced ultrasound (CEUS).

Materials and methods

Two radiologists reviewed 195 imaging studies (17 MDCT, 81 MRI and 97 CEUS examinations) pertaining to 111 FNHs (mean size 3 cm) in 91 patients (mean age 39 years). For each lesion, the readers assessed size, location, echogenicity, attenuation, or signal intensity in comparison with adjacent liver parenchyma on both unenhanced and postcontrast images.

Results

Eighty-nine FNHs (mean size 3.1 cm) were observed in 73 women (mean age 37.9 years) and 22 FNHs (mean size 2.7 cm) in 18 men (mean age 41.2 years). No statistically significant differences were found between men and women in terms of age, FNH lesions per patient (1.22 and 1.21, respectively), size, baseline and enhancement pattern on MRI, CEUS and MDCT (p < 0.05). A central scar in FNHs was depicted in 4/18 (22.2 %) men and 16/63 (25.4 %) women on MRI (p < 0.05), and in 1/2 (50 %) men and 7/15 (46.7 %) women on MDCT (p < 0.05), whereas a spoke-wheel pattern, central scar, and/or feeding vessel were seen in 5/17 (29.4 %) men and 22/80 (27.5 %) women on CEUS (p < 0.05).

Conclusions

Our results did not show any differences in imaging features, age of occurrence and size of FNH between men and women.     

Z-plate在治疗胸腰椎骨折和肿瘤中的应用

目的 :介绍和评估Z -plate在治疗胸腰椎骨折和肿瘤中的作用和价值。方法 :对 15例陈旧性胸腰椎骨折和 1例胸椎肿瘤伴椎管内神经前方受压的患者行椎管侧前方减压、Z -plate内固定术 ,观察术前、术后神经损伤ASIA分级。结果 :随访时间 3～ 18个月 ,平均 9. 2月。ASIA分级 :术前A 3例 ,B 4例 ,C 5例 ,D 4例 ;术后A 1例 ,C 3例 ,D 5例 ,E 7例。结论 :该系统具有稳定性好 ,使用方便、安全 ,内固定材料生物相容性良好 ,术后MRI、CT检查不产生干扰 ,适用于胸腰椎前路减压需要重建脊柱稳定性的治疗     

多层螺旋CT后处理技术在胸腰椎爆裂性骨折诊断中的应用价值

目的:探讨多层螺旋CT后处理技术在胸腰椎爆裂性骨折诊断中的应用价值.方法:43例,48个椎体胸腰椎爆裂性骨折患者行MSCT扫描后,将原始图像进行多平面重组(MPR)、最大密度投影(MIP)、容积再现法(VRT)成像等后处理,分析各图像显示骨折情况的能力,并与手术结果对照.结果:MSCT各种后处理技术联合应用能够准确显示...     

Performance trends in 3000 m open-water age group swimmers from 25 to 89 years competing in the FINA World Championships from 1992 to 2014

We investigated trends in participation, performance and sex difference in performance in 3000 m freestyle in age groups swimmers (25–29 to 85–89 years) competing in the Fédération Internationale de Natation World Masters Championships between 1992 and 2014. During this period, participation increased in women and men. Women and men improved race times across years in all age groups. Women were slower in age groups 25–29 to 70–74 years. In age groups 75–79 and 85–89 years, however, race times were similar for both women and men. Sex difference in performance remained unchanged across years. In summary, performance improved across years in all age groups, men were faster than women up to the age group 70–74 years and women were not able to reduce the sex difference in performance to men across years. For athletes and coaches, an increase in participation and a continuous improvement in performance can be expected in these age group athletes.     

Quantification of the timing of anterior fontanelle closure in a Western Australian population

Closure of the anterior fontanelle is generally accepted to occur within the first two years of life. However, statistical quantification of the precise timing of closure in a Western Australian population has not been explored. The current study examined MDCT scans of 68 individuals between birth and 3.91 years to assess the timing of anterior fontanelle closure. Using OsiriX, the scans are viewed in axial and multi-planar reconstructed (MPR) images and three-dimensional volume rendered reconstructions. Anterior fontanelle fusion status was quantified using two methods: calculating anterior fontanelle area and by taking the oblique linear distances of the open fontanelle. The single greatest proportion of fusion was shown to occur in the first year of life, by which stage only 47.19% of the fontanelle remains unfused (on average by area). There was only one individual demonstrating complete fusion before 1 year of age (0.86 years) with no single individual presenting an open fontanelle beyond 2.4 years of age. The current study outlines statistically quantitated data that facilitates forensic age estimation (either macroscopic or radiographic) specific to Australian individuals from the perinate to early childhood life stages.     

Test of age-related variation in the craniometry of the adult human foramen magnum region: implications for sex determination methods

Sex differences in the foramen magnum region of the cranial base have been identified with varying rates of success. Recent publications demonstrate a continuing strong interest in metric analysis of the foramen magnum region for sex determination despite the generally low expression of cranial base sexual dimorphism. It is important to identify possible age effects on skull base morphometric variables as most reported discriminant analyses use pooled-age samples without assessing the influence of aging on sexual dimorphism. This study examined 135 adult cranial bases (69 males and 66 females) from the St. Bride’s documented skeletal collection in London. Traditional craniometric measurements were recorded and the effect of age on sexual dimorphism of this anatomical region was tested using a variety of statistical analyses including MANOVA and discriminant function analysis. Age-dependent discriminant functions for <50 and >50 years of age were developed and compared. The cross-validated results showed that the <50 years function determined the sex of 69.1 % correctly while the >50 years function achieved 81.3 % correct predictions. However, the high sex biases of these functions (14.4 % and ?17.5 %) severely limit their practical application. A pooled-age discriminant function permitted 71.9 % correct prediction with a sex bias of only ?1.7 %. The statistical analyses also showed no significant age effect on any of the variables, suggesting that a separation by age is not necessary for the development of sex determination methods.     

Multidetector CT of the spine in multiple myeloma: comparison with MR imaging and radiography

OBJECTIVE: The purpose of this study was to compare multidetector CT (MDCT) of the thoracic and lumbar segments of the spine with MR imaging and conventional radiography for bone lesion detection and for evaluating the risk of vertebral fracture in multiple myeloma. SUBJECTS AND METHODS: Eighteen patients with multiple myeloma stage III (according to the criteria of Durie and Salmon) underwent MDCT, conventional radiography, and MR imaging of the lumbar and thoracic spine. MDCT was performed using a standard protocol with no contrast material. Source images were reconstructed using an effective slice thickness of 3 mm with an overlapping reconstruction increment (0.8 mm). Secondary coronal and sagittal multiplanar reformations were exclusively used for establishing the diagnosis. Findings were compared with those of MR imaging and conventional radiography. RESULTS: In all patients, coronal and sagittal multiplanar reformations depicted the extent of osseous destruction and provided detailed information about osseous infiltration and potential bone instability. Compared with conventional radiography, an additional 24 affected vertebrae, 15 additional vertebral fractures, and six vertebrae at further risk of fracture were detected on MDCT. Compared with MR imaging, three additional endangered vertebrae were detected on MDCT. MR imaging alone would have lead to an understaging of five (27.8%) of 18 patients. Using combined radiography and MR imaging, disease in three (16.7%) of 18 patients would have been understaged. CONCLUSION: MDCT seems to be preferable to conventional radiography in evaluating bone destruction in multiple myeloma. In combination with MR imaging, detailed information for staging these tumors is obtained. For the initial staging in patients with multiple myeloma, MDCT in combination with MR imaging seems to be the method of choice.     

Dual-energy CT in vertebral compression fractures: performance of visual and quantitative analysis for bone marrow edema demonstration with comparison to MRI

Objective

To prospectively evaluate the performance of virtual non-calcium (VNC) dual-energy CT (DECT) images for the demonstration of trauma-related abnormal marrow attenuation in collapsed and non-collapsed vertebral compression fractures (VCF) with MRI as a reference standard.

Materials and methods

Twenty patients presenting with non-tumoral VCF were consecutively and prospectively included in this IRB-approved study, and underwent MRI and DECT of the spine. MR examination served as a reference standard. Two independent readers visually evaluated all vertebrae for abnormal marrow attenuation (“CT edema”) on VNC DECT images; specificity, sensitivity, predictive values, intra and inter-observer agreements were calculated. A last reader performed a quantitative evaluation of CT numbers; cut-off values were calculated using ROC analysis.

Results

In the visual analysis, VNC DECT images had an overall sensitivity of 84 %, specificity of 97 %, and accuracy of 95 %, intra- and inter-observer agreements ranged from k?=?0.74 to k?=?0.90. CT numbers were significantly different between vertebrae with edema on MR and those without (p?<?0.0001). Cut-off values provided sensitivity of 85 % (77 %) and specificity of 82 % (74 %) for “CT edema” on thoracic (lumbar) vertebrae.

Conclusions

VNC DECT images allowed an accurate demonstration of trauma-related abnormal attenuation in VCF, revealing the acute nature of the fracture, on both visual and quantitative evaluation.     

Minimal aortic injury of the thoracic aorta: imaging appearances and outcome

The aim of this study is to describe the frequency, computed tomographic angiography (CTA) imaging appearance, management, and outcome of patients who present with minimal thoracic aortic injury. This retrospective study was Institutional Review Board-approved. Eighty-one patients with blunt traumatic aortic injuries (BTAI) were identified between 2004 and 2008, comprising 23 patients with minimal aortic injury (MAI) (mean age, 43.2 years ±18.2 years; 12 males and 11 females) and 58 patients with non-minimal aortic injury (mean age, 42.6 years ±22.7 years). CTA imaging was reviewed for each patient to differentiate those with MAI from those with non-MAI BTAI. Inclusion criteria for MAI on CTA were: post-traumatic abnormality of the internal contour of the aorta wall projecting into the lumen, intimal flap, intraluminal filling defect, intramural hematoma, and no evidence of an abnormality to the external contour of the aorta. Relevant follow-up imaging for MAI patients was also reviewed for resolution, stability, or progression of the vascular injury. The electronic medical record of each patient was reviewed and mechanism of injury, injury severity score, associated injuries, type and date of management, outcome, and days from injury to last medical consultation. Minimal aortic injury represented 28.4 % of all BTAI over the study period. Mean injury severity score (37.1), age (43.2 years), and gender did not differ significantly between MAI and non-MAI types of BTAI. Most MAI occurred in the descending thoracic aorta (16/23, 69 %). Without operative or endovascular repair, there was no death or complication due to MAI. One death occurred secondary to MAI (4.4 %) in a patient who underwent endovascular repair and surgical bypass, compared with an overall mortality rate of 8.6 % in the non-MAI BTAI group (p?=?0.508). The most common CT appearance of MAI was a rounded or triangular intra-luminal aortic filling detect (18/23 patients, 78 %). In a mean of 466 days of clinical follow-up, no complications were observed in survivors treated without endovascular repair or operation. Minimal aortic injury is identified by multi-detector row CT in more than a quarter of cases of BTAI and has a low mortality. Conservative management is associated with an excellent outcome.     

Initial experience with single-source dual-energy CT abdominal angiography and comparison with single-energy CT angiography: image quality, enhancement, diagnosis and radiation dose

Objectives

To assess image quality of virtual monochromatic spectral (VMS) images, compared to single-energy (SE) CT, and to evaluate the feasibility of material density imaging in abdominal aortic disease.

Methods

In this retrospective study, single-source (ss) dual-energy (DE) CT of the aorto-iliac system in 35 patients (32 male, mean age 76.5 years) was compared to SE-CT. By post-processing the data from ssDECT, VMS images at different energies and material density water (WD) images were generated. The image quality parameters were rated on 5-point scales. The aorto-iliac attenuation and contrast-to-noise ratio (CNR) were recorded. Quality of WD images was compared to true unenhanced (TNE) images. Radiation dose was recorded and statistical analysis was performed.

Results

Image quality and noise were better at 70 keV (P?<?0.01). Renal artery branch visualisation was better at 50 keV (P?<?0.005). Attenuation and CNR were higher at 50 and 70 keV (P?<?0.0001). The WD images had diagnostic quality but higher noise than TNE images (P?<?0.0001). Radiation dose was lower using single-phase ssDECT compared to dual-phase SE-CT (P?<?0.0001).

Conclusion

70-keV images from ssDECT provide higher contrast enhancement and improved image quality for aorto-iliac CT when compared to SE-CT at 120 kVp. WD images are an effective substitute for TNE images with a potential for dose reduction.

Key Points

? Multi-detector computed tomography (MDCT) angiography is now a routine procedure. ? Single-source dual-energy CT (ssDECT) can provide simultaneous data with different kilovoltages. ? 70 keV images showed better image quality than conventional single-energy (SE) CT. ? 70 keV images exhibited less image noise in comparison to SE-CT.     

A novel method to estimate adult age from the lumbar vertebral body using 3D PMCT images in Japanese

This study evaluated the age-related changes in the vertebral body using 3D Postmortem CT (PMCT) images and proposed an alternative age estimation formula. The PMCT images of 200 deceased individuals aged 25 to 99 years (126 males, 74 females) were retrospectively reviewed and included in the study. Using the open-source software ITK-SNAP and MeshLab, a 3D surface mesh of the fourth lumbar vertebral body (L4) and its convex hull models were created from the PMCT data. Using their inbuilt tools, volumes (in mm3) of the L4 surface mesh and convex hull models were subsequently computed. We derived VD, defined as the difference in volumes between the convex hull and L4 surface mesh normalized by L4 mesh volume, and VR, defined as the ratio of L4 mesh volume to convex hull volume based on individual L4. Correlation and regression analyses were performed between VD, VR, and chronological age. A statistically significant positive correlation (P < 0.001) between chronological age and VD, (r_s = 0.764, males; r_s = 0.725, females), and a significant negative correlation between chronological age and VR (r_s = -0.764, males; r_s = -0.725, females) was obtained in both sexes. The lowest standard error of the estimate was demonstrated by the VR at 11.9 years and 12.5 years for males and females, respectively. As such, their regression models to estimate adult age were Age = 248.9–2.5VR years, males; Age = 258.1–2.5VR years, females. These regression equations may be useful for estimating age in Japanese adults in forensic settings.     

CT angiography of thoracic outlet syndrome: evaluation of imaging protocols for the detection of arterial stenosis

PURPOSE: The purpose of this work was to evaluate the results of cross-sectional imaging and multiplanar and 3D reconstructions for the detection of thoracic outlet arterial stenosis on CT angiograms. METHOD: Eighty-two patients were prospectively evaluated with CT angiography: in the neutral position and after postural maneuver (164 acquisitions); with contralateral injection of a 24% (Group 1; n = 68) or 30% (Group 2; n = 96) contrast agent; and reconstruction of four sets of images from each acquisition, that is, transverse CT scans, sagittal reformations, and 3D [shaded surface displays (SSD) and volume-rendered (VR)] images. A total of 656 sets of images were blindly and independently interpreted by three readers of variable experience. A consensus interpretation of the four sets of images of each acquisition was used as a standard of reference. RESULTS: The number of examinations coded with an excellent degree of arterial enhancement was significantly higher in Group 2 than in Group 1 [68 (71%) vs. 35 (51%); p < 0.001]. The sensitivity and specificity for detection of arterial stenosis were 67 and 96% for transverse CT scans, 69 and 94% for sagittal reformations, 71 and 99% for 3D-SSDs, and 95 and 100% for VR images. Compared with the standard of reference, a concordant scoring of arterial stenosis severity was found in 54% of transverse CT scans, 84% of sagittal reformations, 78% of 3D-SSDs, and 91% of VR images. Underestimation of stenosis was found in 43% of transverse CT scans and 10% of sagittal reformations; overestimation of stenosis was more frequent on 3D-SSDs (16%) than on VR images (7%). The reader's experience was marked for the interpretation of cross-sectional images but did not influence the interpretation of 3D images. CONCLUSION: Thoracic outlet arterial compression is best depicted with the injection of a 30% contrast agent and reconstruction of VR images.     

翼腭窝的CT三维成像

目的：探讨CT三维成像评价翼腭窝解剖结构的价值。材料和方法：使用Philips Mx8000型多层CT检查仪对5个成人头颅标本进行准直1mm或0．5mm的容积采集，并将数据输入配套Mxview工作站（SGI02）进行三维重建处理，包括容积显示（VR）和三维正交多平面重建（MPR）。鼻腔内侧壁相关结构进行测量并与标本测量进行对比。结果：CT三维正交多平面重建图像可以十分清楚地显示翼腭窝结构及其6个通路结构，VR可以清楚、准确地显示鼻腔内侧壁结构，并均可以获得准确测量。结论：CT容积采集结合合理的三维重建可以直观、立体地显示翼腭窝解剖及其相关通连结构。