A new method to evaluate the elastic modulus of cortical bone by using a combined computed tomography and finite element approach

This study attempted to estimate the elastic modulus of cortical specimens directly from the computed tomography (CT) number (CT). Cubic specimens of fresh bovine femora were tested under compressive loading. The corresponding three-dimensional mesh models of these specimens were established with the aid of CT images. The elastic modulus of each element was determined using the following transfer formula: E=A×(CT)^B. The A and B were determined by matching the simulation results with the experimental force-displacement curves. An optimization approach was used to match the entire specimen sets between simulations and experiments. The results indicated that the elastic modulus of cortical bone can be effectively estimated using a power relationship (E=1.26×10⁻³×(CT)^1.93) directly from the CT number. This procedure eliminates the need to determine the bone density, and therefore reduces the computational time required to define mechanical properties in finite element methods.     

Symphysis pubis distance in adults: a retrospective computed tomography study

Background In this retrospective study, symphysis pubis (SP) distance was measured by transverse computed tomography scans. The relation between the SP distance and age, gender, number of birth and body-mass index was studied. Methods Symphysis pubis joint distances were evaluated for the patients who had undergone abdominal or pelvic computed tomography examination for other medical reasons between the dates of March and May 2007. Anterior, middle, and posterior SP joint distances were measured at transverse planes. Normal joint width in women and men was determined. The relation between obtained values, and age, gender, number of birth, as well as body-mass index was studied. Results Symphysis pubis narrows at anterior concurrently with ageing (r = −0.115; P = 0.007). Narrowing, though less, is also observed at posterior (r = −1.50 P = 0.000); however, middle part does not change (r = 0.030; P = 0.489). Number of birth and body-mass index values do not affect SP width. The widths measured at anterior and middle of the SP were significantly higher in women (P = 0.010 and P = 0.002). Conclusions Osteoarthritic changes develop in SP with ageing. However, osteoarthritis in SP, was found to be clinically and radiologically different from that in other symphyseal joints, as SP hardly ever moves, and vertically processing interpubic disc combines pelvis girdle with counterforces, and is supported by very strong ligaments and muscles. Anterior and middle part of the SP joint is wider in women, because fibrocartilaginous disc is too thick to provide the mobility. An erratum to this article can be found at     

Rotation of the cervical spinal column: a computed tomography in vivo study

Summary The functional anatomy of the spinal column has mainly been studied in the cadaver. The aim of our study was to determine in vivo the normal axial rotation of the cervical column using computed tomography (CT). Sixty subjects, divided into decades from 20 to 80 years of age were studied. The CT protocol comprised an axial cut at the level of the skull base (C0) and at each vertebral level in the neck, in the neutral position (with the nasal septum vertical) and during rotation of the head. To reduce the exposure to irradiation the subjects were divided into two groups: 40 were studied from C0 to the fifth cervical vertebra (C5) with unilateral rotation at C0 of 10°, 20° and 40° (20 rotations to the left and 20 to the right), and 20 subjects were studied from C0 to the first thoracic vertebra (T1) with a maximum rotation at C0 to left and right. The angular position of a vertebra was defined as the anteroposterior axis with reference in the neutral position to the axis of C0, and in rotation was related to its original axis. At each vertebral level the mean angle of rotation and its standard deviation were calculated (n=30) for the successive intermediate and maximum rotations at C0 level. The rotation of the cervical spine took place mainly at two levels: 58% between C1 and C2 and 24% between C3 and C6. The pairs of vertebrae C0/C1 and C2/C3 provided functional couples where the rotation was minimal. Rotation of the lower cervical spine occurred very early. The percentage of rotation with respect to C0 of each cervical vertebra was constant during the successive rotations. The neutral positions of the vertebrae below the atlas were variable. The findings on rotation to left and to right were comparable. This study determined in vivo the distribution of rotation at each vertebral level of the cervical spine during partial and maximum rotation of the skull base. It facilitates the application of CT to the examination of disorders affecting the rotation of the cervical spinal column.

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Anatomie in vivo de la rotation de la colonne cervicale: étude tomodensitométrique

Résumé L'anatomie fonctionnelle de la colonne cervicale a principalement été établie in vitro sur cadavre. Notre étude avait pour but de déterminer in vivo, par utilisation de la tomodensitométrie (TDM), les normes fonctionnelles de la rotation axiale de la colonne cervicale. 60 témoins répartis en décades de 20 à 60 ans et au delà ont été explorés. Le protocole TDM comportait une coupe axiale sur la base du crâne (C0) et sur chaque étage vertébral cervical, en position neutre (septum nasal vertical) et au cours de rotations de la tête. Afin d'obtenir une irradiation faible les sujets étaient répartis en deux groupes : 40 sujets étaient explorés de C0 à C5 pour une rotation unilatérale de C0 à 10°, 20° et 40° (20 rotations droites et gauches), 20 sujets étaient explorés de C0 à T1 pour une rotation maximale de C0 à droite et à gauche. La position angulaire d'une vertèbre était définie par son axe antéro-postérieur rapporté, en position neutre à l'axe de C0, et en rotation à son axe initial. A chaque étage vertébral, l'angle moyen de rotation, et sa déviation standard, étaient calculés (n>30) pour les rotations séquentielles et maximales de C0. La rotation de la colonne cervicale s'effectuait principalement à 2 niveaux; 58 % entre C1 et C2 et 24 % entre C3 et C6. Les doublets vertébraux C0/C1 et C2/C3 formaient des couples fonctionnels. La rotation de la colonne cervicale inférieure était très précoce. Le pourcentage de rotation, par rapport à C0, de chaque vertèbre cervicale était constant au cours des rotations séquentielles. La position neutre des vertèbres sous-atloïdiennes était variable. Les résultats en rotations droite et gauche étaient comparables. Cette étude détermine in vivo la répartition de la rotation axiale de la colonne cervicale à chaque segment vertébral pour des rotations séquentielles et maximales de la base du crâne. Elle permet l'application de cette technique TDM à l'exploration de la pathologie de la rotation de la colonne cervicale.

     

Tumor segmentation from computed tomography image data using a probabilistic pixel selection approach

Automatic segmentation of tumors is a complicated and difficult process as most tumors are rarely clearly delineated from healthy tissues. A new method for probabilistic segmentation to efficiently segment tumors within CT data and to improve the use of digital medical data in diagnosis has been developed. Image data are first enhanced by manually setting the appropriate window center and width, and if needed a sharpening or noise removal filter is applied. To initialize the segmentation process, a user places a seed point within the object of interest and defines a search region for segmentation. Based on the pixels' spatial and intensity properties, a probabilistic selection criterion is used to extract pixels with a high probability of belonging to the object. To facilitate the segmentation of multiple slices, an automatic seed selection algorithm was developed to keep the seeds in the object as its shape and/or location changes between consecutive slices. The seed selection algorithm performs a greedy search by searching for pixels with matching intensity close to the location of the original seed point. A total of ten CT datasets were used as test cases, each with varying difficulty in terms of automatic segmentation. Five test cases had mean false positive error rates less than 10%, and four test cases had mean false negative error rates less than 10% when compared to manual segmentation of those tumors by radiologists.     

Intraobserver and interobserver reliability of radial torsion angle measurements by a new and alternative method with computed tomography

OBJECTIVE:

To evaluate the intraobserver and interobserver reliability of radial torsion angle measurement using computed tomography.

METHODS:

Twelve pairs of cadaver radii and 116 forearms from 58 healthy volunteers were evaluated using axial computed tomography sections measured at the level of the bicipital tuberosity and the subchondral region of the radius. During digital imaging, the angle was formed by two lines, one diametrically perpendicular to the radial tubercle and the other tangential to the volar rim of the distal joint surface. Measurements were performed twice each by three observers.

RESULTS:

In cadaveric bones, the mean radial torsion angle was 1.48° (‐6° ‐ 9°) on the right and 1.62° (‐6° ‐ 8°) on the left, with a mean difference between the right and left sides of 1.61° (0° ‐ 8°). In volunteers, the mean radial torsion angle was 3.00° (‐17° ‐ 17°) on the right and 2.91° (‐16°‐ 15°) on the left, with a mean difference between the sides of 1.58° (0° ‐ 7°). There was no significant difference between each side. The interobserver correlation coefficient for the cadaver radii measurements was 0.88 (0.72 ‐ 0.96) and 0.81 (0.58 ‐ 0.93) for the right and left radius, respectively, while for the volunteers, the difference was 0.84 (0.77 – 0.90) and 0.83 (0.75 – 0.89), respectively. Intraobserver reliability was high.

CONCLUSION:

The described method is reproducible and applicable even when the radial tubercle has a rounded contour.     

Epiphysial ossification centres in iliosacral joints: anatomy and computed tomography

Summary Bilateral apparently bony structures of different forms and sizes located in the inferior and superior ventral parts of the sacroiliac joints were observed on axial CT images of the pelvic region of juvenile patients. No other pathological changes were noted in the sacroiliac joints of these individuals. In one patient the bony structures could also be seen on a conventional plain radiograph. We also examined 3 juvenile autopsy specimens of this joint using radiology, CT, macroscopical evaluation and histology. In two of them, structures could be detected on the CT scans which were similar to those observed in the young patients. Macroscopic investigations revealed the structures to be secondary ossification centres located in the articular cartilage of the lateral part of the os sacrum at the levels of the first and third sacral segments. According to older anatomical literature, these epiphysial ossification centres contribute to the auricular surface of the lateral part of the os sacrum and the free lateral surface of the inferior sacral parts. They can be observed between the ages of 12 and 25 years and begin to synostose with the lateral part around the age of 18 years. In macerated juvenile specimens of the bony pelvis, free ossicles were not detectable in the region of the sacroiliac joints. Histological peculiarities of the ossification process observed are discussed. These physiologically occurring ossification centres are to be differentiated from pathological alterations appearing as bony or bone-like structures on CT scans.

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Points d'ossification épiphysaire des articulations sacro-iliaques : étude anatomique et tomodensitométrique

Résumé Des formations osseuses apparemment bilatérales, de formes et tailles différentes, localisées dans les parties antéro-supérieures et inférieures des articulations sacroiliaques, ont été observées sur les images de coupes axiales de la région pelvienne chez des patients jeunes. Aucune autre modification pathologique n'a été notée au niveau des articulations sacro-iliaques de ces individus. Chez l'un des patients, les structures osseuses pouvaient aussi être observées sur les radiographies standard. Nous avons aussi étudié cette articulation chez 3 sujets anatomiques juvéniles, par la radiographie, la TDM, l'étude macroscopique et histologique. Chez deux d'entre eux des formations osseuses semblables à celles observées chez les patients jeunes pouvaient être détectées sur les coupes TDM. Les recherches macroscopiques ont montré que ces structures étaient des points d'ossification secondaires localisés dans le cartilage articulaire de la partie latérale du sacrum en regard du 1er et du 3e segments sacrés. Si l'on se réfère à une littérature anatomique plus ancienne, ces points d'ossification épiphysaires contribuent à la surface auriculaire de la partie latérale du sacrum et à la surface libre latérale des parties caudales du sacrum. Ils peuvent être observés entre 12 et 25 ans et commencent à fusionner avec les parties latérales aux environs de la 18e année. Sur les bassins osseux provenant de pièces juvéniles conservées, les ossicules libres n'ont pas pu être décelés dans la région des articulations sacroiliaques. Les particularités histologiques du processus d'ossification observé sont discutés. Ces points d'ossification physiologiques doivent être distingués des altérations pathologiques apparaissant au scanner comme des structures osseuses ou assimilées.

     

Carpal bone maturation during childhood and adolescence: Assessment by quantitative computed tomography

The aim of our study was to measure the volume of each carpal bone during childhood and adolescence by image processing from computed tomography (CT) scans, and to analyze the relationship between the eight carpal bones. Thirteen CT scans were performed in nine normal prepubertal, peripubertal and post-pubertal children, six boys and three girls, aged 5-14 years. Each scan was processed in order to extract the carpal bones. The volume was computed for each bone. There was a significant correlation between carpal bone volume and age (0.55 < r < 0.79), and a very strong correlation between the volume of a given carpal bone and the volume of all the others, whatever the age (0.87 < r < 0.99, p < 0.01). Image processing is a potentially useful method for assessing bone maturation. The constant ratio between carpal bone volumes indicates that these bones interact with each other in wrist bone maturation     

Three-dimensional motion patterns of the carpal bones: an in vivo study using three-dimensional computed tomography and clinical applications

A three-dimensional (3D) CT technique was developed to analyze in vivo segmental carpal kinematics. Transverse CT data of the distal forearm, carpals and proximal metacarpals was acquired and 3D reconstructed in various wrist positions. Carpal kinematics were analyzed in two groups of 20 asymptomatic volunteers, one group in neutral position, flexion and extension (45°), and the other group in neutral position, radial (15°) and ulnar deviation (30°). Qualitative analysis included the 3D study of carpal anatomy, and comparison of carpal bone position between the different sets of data obtained. Carpal bone motion was quantified using rigid body and finite helical axis concepts. The results, although agreeing in principle with previous findings, showed important individual variations in carpal bone motion. Clinical applications were conducted in a series of 25 patients with various wrist disorders. There was no significant difference between the injured wrist and the heterolateral, asymptomatic wrist, but there was a significant difference between asymptomatic volunteers and both the injured wrist and heterolateral wrist of patients. In particular, scaphoid motion was altered bilaterally in our patient group, suggesting the existence of anatomic and/or kinematic factors predisposing to certain carpal pathologies. This hypothesis needs to be confirmed and refined.     

Subaortic left brachiocephalic vein: computed tomography and magnetic resonance angiography findings

A case of anomalous (subaortic) position of the left brachiocephalic vein was incidentally detected on computed tomography images. Magnetic resonance angiography was performed to demonstrate the relationship of this vessel with other vascular structures. The anomalous vein was formed by the union of the left internal jugular and left subclavian veins. This vein passed downward along the left lateral side of the aortic arch, entered the aorticopulmonary window, descended in the mediastinum between the ascending aorta and the trachea and joined with the right brachiocephalic vein to form the superior vena cava. No cardiac anomalies accompanied the subaortic left brachiocephalic vein in the present case. We present the computed tomography and magnetic resonance angiography findings of this rare anomalous vein.

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Electronic Supplementary Material The french version of this article is available in the form of electronic supplementary material and can be obtained by using the Springer Link server located at .

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Veine brachiocéphalique gauche sous-aortique. Constatations en tomodensitométrie et en angiographie par résonance magnétique

Résumé Un cas de position anormale sous-aortique de la veine brachiocéphalique gauche a été détecté accidentellement au cours d'un scanner. L'angiographie par résonance magnétique a été réalisée pour montrer les rapports de ce vaisseaux avec les autres structures vasculaires. La veine anormale était formée par l'union des veines jugulaire interne et subclavière gauches. La veine se dirigeait vers le bas le long du côté gauche de l'arc de l'aorte, traversait la fenêtre aorto-pulmonaire, descendait dans le médiastin entre l'aorte ascendante et la trachée et rejoignait la veine brachio-céphalique droite pour former la veine cave supérieure. Aucune autre anomalie cardiaque n'accompagnait la veine brachiocéphalique gauche sous-aortique dans le cas présenté. Nous présentons les données tomodensitométriques et d'angiographie par résonance magnétique concernant cette rare veine anormale.

     

Nanoparticulate carrier containing water-insoluble iodinated oil as a multifunctional contrast agent for computed tomography imaging

Contrast-enhanced computed tomography (CT) imaging is a valuable and routine strategy for the clinical diagnosis of various diseases. However, all current CT contrast agents are liquids, so they flow through the blood vessels and disappear very quickly by extravasation. If it were possible to make a blood-compatible particulate contrast agent, we could highlight a particular tissue by either passive or active targeting. In this work, Pluronic F127 and a naturally iodinated compound, Lipiodol, were used to form radiopaque nanoreservoir structures. The resultant nanoparticles have a stable structure at high concentrations, sufficient X-ray absorption, a safety profile similar to or better than that of Iopromide, and a longer circulation time than commercial iodinated preparations. The utility of the resultant radiopaque nanoparticles as a contrast agent was tested using micro-SPECT/CT imaging in vivo. Together with the very good solubility of hydrophobic drugs (e.g., Taxol) in Lipiodol, these results suggest the possibility that these particulate structures and their bioconjugates could become functional CT contrast agents that could deliver therapeutic agents to a particular tissue.     

Measurements of maxillary sinus volume and dimensions by computed tomography scan for gender determination

IntroductionHumans are sexually dimorphic. Identification of remnants of skeletal and decomposing parts of human is one of the most difficult skills in forensic medicine. Forensic anthropologists often receive an incomplete skeleton, which are recovered fragmented but some bones are often recovered intact e.g. maxilla. However, typical identification methods may be inconclusive, especially when certain extreme post-mortem changes have developed.The aim of this study is to compare the size and volume of the maxillary sinus between males and females by CT Scan for gender determination.Methods102 cases (61 males & 41 females) were studied from Gwalior region. The sinus measurements were taken from series of CT Head images on DICOM viewing software using inbuilt electronic caliper. Independent sample t-test & discriminant function analysis were done using Graph pad prism & Word Excel Sheet windows 2007 version.ResultsThe dimensions & volume of the maxillary sinus of male was found to be larger than those of female & this difference was statistically significant (p < 0.05) for sinus AP & Volume. 65.16% of males & 68.9% of females were sexed correctly & the overall percentage for sexing maxillary sinuses correctly was 67.03% & sinus AP was the best discriminant parameter with an overall accuracy of 69.81%.DiscussionWe can conclude that CT measurements of maxillary sinus dimensions & volume may be useful for identification of gender in forensic anthropology to some extent when other methods are inconclusive.     

Diabetes mellitus and brain atrophy: A computed tomography study in an elderly population

Previous studies have suggested that noninsulin dependent diabetes mellitus (NIDDM) could lead to learning and memory deficits. We studied cognitive performance and computed tomography (CT) findings of the brain in elderly subjects with drug treated NIDDM (n = 12), with diet treated NIDDM (n = 13), and in nondiabetic individuals (ND, n = 59). The cognitive performance (orientation and uptodate knowledge, praxic functions, understanding of speech, expressive speech, memory, general reasoning) did not differ between the groups. The drug treated diabetics had more pronounced central temporal atrophy compared to that in the ND subjects as evidenced by wider right temporal horn (ANCOVA adjusted for age, p = 0.011). The drug treated diabetics (all women) also had wider frontal horns than did the ND women. The CT measures of diet treated diabetics were comparable with those of the ND group. The fasting glucose level was positively correlated with the width of the right temporal horn but not with other CT measures in diabetic subjects. The results suggest that NIDDM and poor glucose control may carry a risk for accelarated brain atrophy in the elderly.     

Volume variation of mastoid pneumatization in different age groups: a study by three-dimensional reconstruction based on computed tomography images

Although there have been some reports that measured the size of mastoid pneumatization, only a few studies have reported the age-related variations in the mastoid air cell system using three-dimensional (3D) reconstruction techniques of computed tomography (CT) images. We performed a retrospective, cross-sectional study. A 3D reconstruction based on CT images was performed on 199 ears of 102 patients (age range 6–84 years) without otologic disease by a surface-rendering algorithm. The results showed that mastoid pneumatization continued to grow until the third decade. Thereafter, it declined slowly, and then rapidly after the seventh decade. No statistically significant difference was found between male and female or between right and left sides. There was a significant difference between the larger and smaller sides of individuals. The volume measurement technique based on the 3D reconstruction technique reported here is widely available, highly accurate and easy to perform.     

Bone tunnel change develops within two weeks of double-bundle anterior cruciate ligament reconstruction using hamstring autograft: A comparison of different postoperative immobilization periods using computed tomography

Background

The purpose of this study was to evaluate bone tunnel changes following anterior cruciate ligament (ACL) reconstruction during the early postoperative period using computed tomography (CT), and to understand the impact of postoperative immobilization on these changes.

Positron emission tomography alone,positron emission tomography-computed tomography and computed tomography in diagnosing recurrent cervical carcinoma: a systematic review and meta-analysis

Introduction

The aim of the study was to assess systematically the accuracies of positron emission tomography (PET), PET/computed tomography (CT), and CT in diagnosing recurrent cervical cancer.

Material and methods

We searched for articles published from January 1980 to June 2013 using the following inclusion criteria: articles were reported in English; the use of PET, interpreted with or without the use of CT; use of CT to detect recurrent cervical cancer; and histopathologic analysis and/or close clinical and imaging follow-up for at least 6 months. We extracted data to calculate sensitivity, specificity, summary receiver operating characteristic curves, and the area under the receiver operating characteristic curve (AUC) as well as test for heterogeneity.

Results

In 23 included studies, PET had the highest pooled specificity at 92% (95% CI: 90–94), whereas PET/CT had the highest pooled sensitivity at 94% (95% CI: 90–97). The area under the curve (AUC) of PET alone, PET/CT, and CT were 0.9594, 0.9508, and 0.9363, respectively. Results of the pairwise comparison between each modality show that the specificity of PET was higher than that of PET/CT (p < 0.05). The difference in the pooled sensitivities and AUC of PET alone and PET/CT showed no statistical significance. No evidence of publication bias was found. However, evidence of heterogeneity was observed.

Conclusions

The PET/CT may be a useful supplement to current surveillance techniques, particularly for patients with negative CT imaging. However, in terms of diagnostic accuracy, interpreted CT images may have limited additional value to PET in detecting recurrent cervical cancer.     

Prevalence and correlates of patient-centred preparatory information provision to computed tomography and magnetic resonance imaging outpatients: A cross-sectional study

Objective

Responsiveness to information preferences is key to high-quality, patient-centred care. This study examined the top ten preparatory information items not delivered in accordance with medical imaging outpatients’ preferences, and patient characteristics associated with reporting a greater number of unmet information preferences.

Development of a method to quantitatively monitor the effect of inhibition of nitric oxide synthase on tumour vascular activity using dynamic contrast-enhanced computed tomography

This study was undertaken to develop a method to quantitatively monitor the effect of inhibition of nitric oxide synthase (NOS) on tumour vascular activity using dynamic contrast-enhanced computed tomography (DCE-CT). The DCE-CT studies were performed in 13 anaesthetized rats bearing tumours. To investigate the effect of NOS inhibition, N-nitro-L-arginine (L-NNA) was intravenously administered in eight rats, while only the vehicle was administered in five rats. The contrast enhancement (CE) images were generated by subtracting the CT images before and after the administration of contrast agent. The tumour blood volume (TBV) images were also generated. The CE significantly decreased after L-NNA administration, while there were no significant changes when only the vehicle was administered. There was a good correlation between CE and TBV, suggesting that CE mainly reflects TBV. In conclusion, the present method appears to be useful for monitoring the effect of NOS inhibition on tumour vascular activity.