Optimization of 3-dimensional imaging of the breast region with 3-dimensional laser scanners

The anatomic conditions of the female breast require imaging the breast region 3-dimensionally in a normal standing position for quality assurance and for surgery planning or surgery simulation. The goal of this work was to optimize the imaging technology for the mammary region with a 3-dimensional (3D) laser scanner, to evaluate the precision and accuracy of the method, and to allow optimum data reproducibility. Avoiding the influence of biotic factors, such as mobility, we tested the most favorable imaging technology on dummy models for scanner-related factors such as the scanner position in comparison with the torso and the number of scanners and single shots. The influence of different factors of the breast region, such as different breast shapes or premarking of anatomic landmarks, was also first investigated on dummies. The findings from the dummy models were then compared with investigations on test persons, and the accuracy of measurements on the virtual models was compared with a coincidence analysis of the manually measured values. The best precision and accuracy of breast region measurements were achieved when landmarks were marked before taking the shots and when shots at 30 degrees left and 30 degrees right, relative to the sagittal line, were taken with 2 connected scanners mounted with a +10-degree upward angle. However, the precision of the measurements on test persons was significantly lower than those measured on dummies. Our findings show that the correct settings for 3D imaging of the breast region with a laser scanner can achieve an acceptable degree of accuracy and reproducibility.     

应用新型三维扫描技术建立单侧唇裂修复术评价方法的研究

目的：利用三维扫描仪（Three Dimensional Sensing System,3DSS）结合逆向工程软件建立一种新型单侧唇裂修复手术效果的评价方法。方法：利用3DSS对单侧唇裂（III度）患儿进行面部扫描,获得患儿术前及术后面部形态数据,将其导入逆向工程软件Geomagic Studio 10.0中进行重建并进行数据测量。结果：该方法能快速、准确地完成患儿面部形态的重建,并可以在软件中完成面部标志点的标定、既定标志点间距离的测量,并以此为基础建立一种新型评价单侧唇裂修复术后效果的方法。结论：利用三维扫描仪结合逆向工程软件可以建立一种评价单侧唇裂修复手术效果的方法,且该方法客观、准确、可操作性好,值得推广。     

Virtual neuroendoscopy, a comparative magnetic resonance and anatomical study.

We evaluated the usefulness and reliability of intraventricular virtual neuroendoscopy based on a comparative anatomical study. Virtual intraventricular endoscopic images were calculated from 3D magnetic resonance images in five anatomic specimens. Contiguous 1.2 mm slices of the specimen heads were acquired at a 1.5 T MR scanner using a 3D-gradient echo sequence. The images were then transferred to an independent 3D-workstation (Sun Spark 20). After scanning the specimen heads, real endoscopy within the cerebral ventricles of these brains was performed with a standard rod lens system. Comparison between real and virtual endoscopic views of the intraventricular topography was based on the same anatomical reference and landmarks. Acquisition of MR data and virtual image post-processing have been possible in all specimens. The virtual endoscopic images of the ventricles were comparable to the intraventricular views obtained by a standard rod lens system. Virtual intraventricular neuroendoscopy can be employed for planning and simulating neuroendoscopic procedures. It enables the neurosurgeon to simulate the endoscopic procedure within the cerebral ventricles on the basis of the patient's individual anatomy prior to surgery.     

Photogrammetric Facial Analysis of Attractive Korean Entertainers

Background  The authors have developed a new digital photogrammetric method of facial analysis known as balanced angular and proportional analysis (BAPA). Using BAPA, the authors analyzed the faces of attractive Korean entertainers. Methods  The BAPA approach involves 28 landmarks and 14 measurements (10 proportional and 4 angular measures). Standardized mean angular values of famous entertainers are referred to as recommended aesthetic mean angles (RAMA) and the mean proportional values as the recommended aesthetic mean proportions (RAMP). In this study, 30 frontal views of famous Korean entertainers (15 men and 15 women) were collected from Internet Web pages, and the data analyzed using V-ceph. A t test (with the significance level set at a p value of 0.05) was performed to analyze male versus female comparisons. Results  Significant between-group differences (p < 0.05) were found for P-lower face, P-eye height, P-lip, P-interangle, and the mandibular contour in the frontal views. Famous Korean female entertainers differ from famous male entertainers. The women have a shorter lower face, larger eyes, smaller lips, and a more slender and oval shape of the mandibular soft tissue contour. Conclusions  The authors insist that facial analysis should take into consideration racial, ethnic, and gender differences. The BAPA approach is a new practical and simple method for photogrammetric facial analysis. Using the authors’ method, more advanced and automated computer systems for analyzing human faces may be developed.     

Anthropometric 3D-body scanning in idiopathic scoliosis

PURPOSE: A new, non-invasive method of 3D-measurement is presented which allows the spatial recording of the entire body surface in scoliotic deformities. The application of the system is examined to raise automatically anthropometric data of patients with scoliosis. METHOD: 32 patients with idiopathic scoliosis were examined (average age 15.3 years, 25 girls and 7 boys, Cobb angles between 11 and 72 degrees). The whole body recording is carried out with a 3D laser scanner. During the measuring process the patient is standing in a frame. Within the measuring time of 15 seconds the body surface is registered by lasers and four cameras. The measured values are converted to a digital 3D model. The resolution is up to 1 mm. On the digital 3D model an automatic calculation of defined anthropometric parameters were carried out. Each patient was measured twice. RESULTS: In all patients a virtual 3D model with a high surface accuracy was obtained. Was the model the typical body asymmetries in scoliotic deformities were visible. The automatic calculation shows a mean deviation of the second measurements between 0.23 and 0.71 cm. The reproducibility depended on the type of the measured parameters. CONCLUSIONS: The laser scanning system allows a rapid, touchless and accurate 3D measurement of the whole body in scoliotic deformities. To determine anthropometric parameters the reproducibility of the automatic calculation is sufficient in most parameters.     

Functional topography of the low postcentral area

OBJECT: The goal of this study was to establish a reliable method for identification of face and tongue sensory function in the lower central area. METHODS: All positron emission tomography (PET) clinical activation studies performed over a 3-year period at the Montreal Neurological Institute and Hospital were evaluated by coregistering the PET images with three-dimensional reconstructions of magnetic resonance images obtained in the same patients. In addition to stereotactic coordinates and measurements based on distance from the sylvian fissure, gyral and sulcal landmarks were analyzed to determine their reliability in localizing the sensory areas of the tongue and lower face. The convolutional anatomy of the central area is an important guide to the identification of function. The sensory area of the tongue is recognized as a triangular region at the base of the postcentral gyrus; the sensory area of the lower face resides in the narrowed portion of the postcentral gyrus, immediately above the tongue area. CONCLUSIONS: Cortical landmarks such as the substrata of tongue and face sensory impressions are more reliable guides than stereotactic coordinates or measurements for localizing function.     

Computer assisted pelvic surgery: registration based on a modified external fixator.

A fundamental step in Computer Assisted Surgery (CAS) is the registration, when the preoperative virtual data and the corresponding operative anatomy of the region of interest are merged. To provide exact landmarks for anatomical registration, a tubular external fixator was modified. Two intact pelvic bones (one artificial foam pelvis and one cadaver specimen) were used for the experimental setup. Registration was carried out using a standardized protocol for anatomy-based registration in the control group; anatomical registration was achieved using a modified external fixator in the study group. This external fixator had titanium fiducials wedged into the fixator carbon tubes serving as landmarks for paired-point registration. The tubes were used for surface registration. The standard anterior pelvis fixator assembly was augmented with additional bilateral tubes oriented towards the posterior, enabling registration of the sacroiliac areas. The accuracy of registration was checked by "reversed verification", where the examiner used only the screen display to control the virtual position of the pointer tip in relation to selected landmarks. By virtual matching, the real distance was measured with a digital caliper. We defined the verification as "accurate" when the residual distance was less than 1 mm; "acceptable" when it was between 1 mm and 2 mm; and "insufficient" when it exceeded 2 mm. The paired T-test with significance levels of p < 0.05 was used for statistical analysis. The anatomical registration based on the external fixator landmarks was statistically as accurate as that obtained using anatomical landmarks on the pelvic bone. This study concludes that the external fixator, a conventional tool in the management of acute traumatic pelvic instability, can also be useful for landmark registration in CAS.     

基于X线的颅面部软组织三维重建及测量分析研究

目的：利用头颅定位X线片实现颅面部软组织的三维重建及测量。方法：同期分次摄取侧位、45°位和正位头颅定位X线片。利用侧位和45°位X线片上相匹配的外加金属标志点,获得颅面部软组织的三维信息,进行颅面部软组织形态的三维重建。在所建面部三维模型基础之上选8个解剖标志点,进行10项测量,并与人群的正常值进行比较研究。结果：利用侧位和45°位的两张X线片,对颅面部软组织实现三维重建。建立了颅面部软组织的三维测量系统,测量结果同正常值相比较,除面宽和下颌宽有较大的差异外,测量值都具有很好的同一性,面部比例指数除去面宽和下颌角宽的影响大多数都有较好的一致性。结论：本系统基于头颅定位X线片实现颅面部软组织的三维重建和测量,为面部畸形的诊断,正颌手术的定量化手术设计,术后疗效评价提供新的技术方法。     

Surface landmarks of the facial nerve trunk: a prospective measurement study

Background: Facial nerve identification and preservation is the key to safe parotidectomy in most clinical situations. Traditional approaches to the main trunk have depended solely on internal landmarks but localization may further be enhanced if data are avail­able on its position with reference to neighbouring external features. Methods: Prospective measurements were taken on a series of parotidectomy patients intraoperatively. Using that spot on the main trunk 10 mm proximal to its bifurcation as the reference point, the depth from the skin and its cranio‐caudal distance from the summit of the tragus were measured. Results: Thirty‐three patients were included, whose body mass index showed that they had average body build. The reference point nerve was 23.6 mm (SD = 5.1 mm) from the skin surface, and 18.8 mm (SD = 6.0 mm) caudal to the tragus. Conclusion: Measurements relating to the siting of the facial nerve trunk were obtained live at operation. This information should be helpful in the initial mobilization of the parotid gland from its posterior relations and in facilitating the classical internal landmarks in the 3‐D localization of the main trunk, thereby allowing quicker and safer parotidectomy.     

基于网络的面部畸形患者三维数据库的建立

目的 通过三维扫描仪采集30例面部畸形患者的三维面部数据,建立基于网络的数据库,以期为临床治疗提供依据.方法 采用三维扫描仪获取患者面部各点的空间信息,并通过逆向工程软件对获得的三维点云数据进行曲面重建,构建三维模型.数据库系统包括患者的基本信息、疾病信息和手术信息.网络访问系统采用Java语言编写.结果 数据库各模块之间链接可靠,基于网络的查询系统方便准确,因而具有数据挖掘功能.图像分析系统提供的患者面部三维模型的显示,可以在线交互式地对模型进行观察.结论 所建立的数据库和网络系统符合整形外科的专业要求,可用于临床治疗以及科研教学.     

Comparison of Facial Proportions and Anthropometric Norms Among Turkish Young Adults With Different Face Types

Background This study aimed to determine the prevalence of three different face types among Turkish young adults based on facial indices, to assess and compare the vertical and horizontal dimensions for each type, and to establish anthropometric norms for Turkish adults. Methods A total of 173 healthy young adults (83 females and 90 males) 17 to 25 years of age were examined. Using anthropometric landmarks, 8 horizontal and 10 vertical direct measurements were made with a millimetric compass. Results Using facial indices, 59 of the 173 subjects were classified as euryprosopic, 49 as mesoprosopic, and 65 as leptoproposic. In the total evaluation of both groups, all the parameters were higher in the males except forehead heights 1 and 2. A comparison of face types in females and males separately showed no significant differences between the parameters. Conclusions The data presented in this study may help plastic surgeons and orthodontists objectively determine the relationships between facial structures for different face types. Additionally, the facial anthropometric norms derived from this study may be useful in the treatment of Turkish patients.     

Soft tissue facial volumes and shape in skeletal Class III patients before and after orthognathic surgery treatment.

BACKGROUND: To obtain the best surgical results in orthognathic surgery, treatment planning and the evaluation of results should be performed on measurable three-dimensional reproductions of the face of the patients, and compared to reference subjects. METHODS: Seven women aged 18-35 years, all with a skeletal Class III and mandibular asymmetry, were assessed both before (on average, 2 months) and after (on average, 10.7 months) surgical intervention (mandibular reduction by sagittal split osteotomy and LeFort I maxillary advancement). The three-dimensional coordinates of 50 soft tissue facial landmarks (face, eyes, nose, mouth and lips, ears) were collected with a noninvasive, electromagnetic digitizer; facial volumes were estimated, and compared to reference values collected in 87 healthy women of the same age and ethnic group. Inter-individual modifications in facial shape were also assessed. RESULTS: Before surgery the patients had smaller faces than the reference women, with larger lower lips and noses. A large within-group variability was found. Surgical treatment significantly reduced total facial volume and mandibular volume, increased total and upper lip volumes (Student's t test, p<0.05), and made all values more homogenous within the group. Shape differences were significantly larger before than after surgery. On average, right side gonion was the landmark that moved the most, closely followed by menton, while the tragi and ala nasi moved the least. The three-dimensional approach used in this study enabled quantitative evaluation of the final soft tissue results of surgery, without submitting the patients to invasive procedures.     

BoneMorphing versus freehand localization of anatomical landmarks: consequences for the reproducibility of implant positioning in total knee arthroplasty.

OBJECTIVE: This study analyzed the influence of the acquisition method in image-free computer-assisted total knee arthroplasty (CAS-TKA), and the reproducibility of implant planning using BoneMorphing, a 3D morphometric model obtained by a 3D-to-3D elastic registration of statistical models to sparse point clouds acquired directly on the bone surface with a pointer. MATERIALS AND METHODS: Five surgeons (one expert, four trainees) each performed a CAS-TKA hybrid protocol based on morphometric models and landmarks on a cadaveric knee 10 times. In addition, several additional landmarks were digitized during each acquisition. The reproducibility of the implant positioning and sizing, as determined by an implant planning algorithm with morphometric models, was compared to direct digitization accuracy. RESULTS: Femoral and tibial implant positioning parameters with the hybrid protocol resulted in intra-surgeon standard deviations (SDs) of less than+/-1.4 degrees for rotation and 1.9 mm for translation for all surgeons in all directions except for tibial axial rotation (the only parameter determined by a digitized landmark and not recomputed in the 3D model). The variability in individual landmark digitization varied from 2 to 5 mm SD for certain landmarks, with ranges of 15-25 mm across all surgeons. The comparison study showed an improvement in femoral rotation reproducibility with the morphometric model when using the posterior condylar axis. Tibial implant reproducibility for each method was comparable, with the morphometric model giving better results in well-digitized areas such as the tibial plateau. CONCLUSION: A CAS-TKA protocol based on a deformed statistical model offers reproducible implant positioning. Some landmarks, such as distal condyles, show sufficient reproducibility in the direction of interest, while others, such as the anterior tibial tubercle, can lead to hazardous implant positioning. This should be taken into consideration when designing a CAS-TKA system with bony landmarks. In areas where a sufficient number of points have been digitized with good coverage, such as on the distal and posterior femoral condyles or the tibial plateau areas, the information derived from the 3D model is more accurate and reproducible than that derived from digitization. Good training and a guiding user interface are essential to guarantee coverage quality.     

Placement of pedicle screws in the human cadaveric cervical spine: comparative accuracy of three techniques

STUDY DESIGN: This investigation was conducted in two parts. In the first part, a morphometric analysis of critical cervical pedicle dimensions were measured to create guidelines for cervical pedicle screw fixation based on posterior cervical topography. In the second part of the study, a human cadaver model was used to assess the accuracy and safety of transpedicular screw placement in the subaxial spine using three different surgical techniques: 1) using surface landmarks established in the first part of the study, 2) using supplemental visual and tactile cues provided by performing laminoforaminotomies, and 3) using a computer-assisted surgical guidance system. OBJECTIVE: To assess the accuracy of transpedicular screw placement in the cervical spine using three surgical techniques. SUMMARY OF BACKGROUND DATA: A three-column fixation device implanted to secure an unstable cervical spine can be a valuable tool with a biomechanical advantage in the spine surgeon's armamentarium. Despite this advantage, concerns over surgical neurovascular complications have surfaced. Cadaver-based morphometric measurements used to guide the surgeon in the placement of a pedicle screw show significant variability, raising legitimate concerns as to whether transpedicular fixation can be applied safely. METHODS: Precise measurements of 14 human cadaveric cervical spines were made by two independent examiners of pedicle dimensions, angulation, and offset relative to the lateral mass boundaries. On the basis of this analysis, guidelines for pedicle screw placement relative to posterior cervical topography were derived. In the second part of the study, 12 human cadaveric cervical spines were instrumented with 3.5-mm screws placed in the pedicles C3-C7 according to one of three techniques. Cortical integrity and neurovascular injury were then assessed by obtaining postoperative computed tomography scans (1-mm cuts) of each specimen. Cortical breaches were classified into critical or noncritical breaches. RESULTS: Linear measurements of pedicle dimensions had a wide range of values with only fair interobservercorrelation. Angular measurements showed similarangulation in the transverse plane (40 degrees ) at each level. With respect to the sagittal plane, both C3 and C4 pedicles were oriented superiorly relative to the axis of the lateral mass, whereas the C6 and C7 pedicles were oriented inferiorly. The dorsal entry point of the pedicle on the lateral mass defined by transverse and sagittal offset had similar mean values with wide ranges, although there often was excellent correlation between observers. There were no significant interlevel, right/left, or male/female differences noted with respect to offset. Using one of three techniques, 120 pedicles were instrumented. In group 1 (morphometric data): 12.5% of the screws were placed entirely within the pedicle; 21.9% had a noncritical breach; and 65. 5% had a critical breach. In group 2 (laminoforaminotomy), 45% of the screws were within the pedicle; 15.4% had a noncritical breach; and 39.6% had a critical breach. In group 3 (computer-assisted surgical guidance system), 76% of the screws were entirely within the pedicle; 13.4% had a noncritical breach; and 10.6% had a critical breach. Regardless of the technique used, the vertebral artery was the structure most likely to be injured. CONCLUSIONS: On the basis of the morphometric data, guidelines for cervical spine pedicle screw placement at each subaxial level were derived. Although a statistical analysis of cadaveric morphometric data obtained from the cervical spine could provide guidelines for transpedicular screw placement based on topographic landmarks, sufficient variation exists to preclude safe instrumentation without additional anatomic data. Insufficient correlation between different surgeons' assessments of surface landmarks attests to the inadequacy of screw insertion techniques in the cervical spine based on such specific topographic guide     

Preoperative anthropometric analysis of the cleft child's face: a comparison between groups

This study examines the facial surfaces of different groups of cleft babies aged up to eleven months, prior to any corrective surgery, with the aim of identifying and assessing differences in their facial morphology. Measurements of standard anthropometric landmarks were made on plaster casts taken pre-operatively of the faces of babies presenting for surgical correction of lip and palate deformities. Periorbital and mid face measurements show no difference between control and cleft groups. The nasal base is shown to be wider in infants with cleft lip on both cleft and non-cleft sides. Upper lip measurements indicate shortening, lateral deviation and superolateral rotation. A diagrammatic model is proposed to illustrate facial anatomy in control and cleft individuals. Modifications to the technique are proposed. Further study in this field is suggested, in order to produce a comprehensive database of facial morphological changes in the cleft and non-cleft populations both pre-operatively and over time, with a view to producing a potential redefinition of the cleft syndrome based on anthropometric principles.     

Intra- and extra-articular planes of reference for use in total hip arthroplasty: a preliminary study

Purpose

Acetabular component malalignment in total hip arthroplasty can lead to potential complications such as dislocation, component impingement and excessive wear. Computer-assisted orthopaedic surgery systems generally use the anterior pelvic plane (APP). Our aim was to investigate the reliability of anatomical landmarks accessible during surgery and to define new potential planes of reference.

Methods

Three types of palpations were performed: virtual, on dry bones and on two cadaveric specimens. Four landmarks were selected, the reproducibility of their positioning ranging from 0.9 to 2.3 mm. We then defined five planes and tested them during palpations on two cadaveric specimens.

Results

Two planes produced a mean orientation error of 5.0° [standard deviation (SD 3.3°)] and 5.6° (SD 2.7°).

Conclusions

Even if further studies are needed to test the reliability of such planes on a larger scale in vivo during surgery, these results demonstrated the feasibility of defining a new plane of reference as an alternative to the APP.     

New aspects of breast volume measurement using 3-dimensional surface imaging

Precise and objective calculation of breast volume is helpful to evaluate the aesthetic result of breast surgery, but traditional methods are unsatisfactory. Three-dimensional (3D) scanning of the body surface allows reproducible and objective assessment of the complex breast region but requires further investigation before clinical application. The main goal of this study was to investigate the precision and accuracy of breast volume measurement using 3D body scanning. Five independent observers standardized the 3D scanning method using 2 dummy models (n = 200) and examined its applicability with 6 test subjects and 10 clinical patients (n = 2220). Breast volume measurements obtained with the 3D-scanner technology were compared with reference measurements obtained from test subjects through nuclear magnetic resonance imaging. The mean deviation of the breast volume measurements of 1 test subject by all observers, expressed as percentage of volume, was 2.86 +/- 0.98, significantly higher than the deviation for the dummy models, 1.65 +/- 0.42 (P < 0.001). With respect to all clinical patients, the mean measurement precision obtained preoperatively was less precise than that obtained postoperatively (3.31 +/- 1.02 versus 1.66 +/- 0.49, respectively). Interobserver differences in measurement precision were not statistically significant. The mean breast volumes obtained by nuclear magnetic resonance imaging (441.42 +/- 137.05 mL) and 3D scanning (452.51 +/- 141.88 mL) significantly correlated (r = 0.995, P < 0.001). Breast volume measurement with 3D surface imaging represents a sufficiently precise and accurate method to guarantee objective and exact recording.     

Surface structure of retrieved ICLH femoral cups

We characterized the surface structure of 21 retrieved femoral ICLH cups, as an indirect measure of surface damage, with an optical scanner specially developed for surface roughness measurements. 3 unused cups were measured and served as controls. The mean insertion time was 10 (5-15) years. 5 areas on each cup were measured, 1 on the top and 4 at the edge. The mean value of 3 different, commonly used, surface roughness parameters was calculated for the edge measurements. We found no correlation between the surface topography and clinical patient data such as age, body-weight, head-shaft angle, implantation time and wear of the polyethylene socket.     

Electrophysiological correlates of rapid spatial orienting towards fearful faces

We investigated the spatio-temporal dynamic of attentional bias towards fearful faces. Twelve participants performed a covert spatial orienting task while recording visual event-related brain potentials (VEPs). Each trial consisted of a pair of faces (one emotional and one neutral) briefly presented in the upper visual field, followed by a unilateral bar presented at the location of one of the faces. Participants had to judge the orientation of the bar. Comparing VEPs to bars shown at the location of an emotional (valid) versus neutral (invalid) face revealed an early effect of spatial validity: the lateral occipital P1 component (approximately 130 ms post-stimulus) was selectively increased when a bar replaced a fearful face compared to when the same bar replaced a neutral face. This effect was not found with upright happy faces or inverted fearful faces. A similar amplification of P1 has previously been observed in electrophysiological studies of spatial attention using non-emotional cues. In a behavioural control experiment, participants were also better at discriminating the orientation of the bar when it replaced a fearful rather than a neutral face. In addition, VEPs time-locked to the face-pair onset revealed a C1 component (approximately 90 ms) that was greater for fearful than happy faces. Source localization (LORETA) confirmed an extrastriate origin of the P1 response showing a spatial validity effect, and a striate origin of the C1 response showing an emotional valence effect. These data suggest that activity in primary visual cortex might be enhanced by fear cues as early as 90 ms post-stimulus, and that such effects might result in a subsequent facilitation of sensory processing for a stimulus appearing at the same location. These results provide evidence for neural mechanisms allowing rapid, exogenous spatial orienting of attention towards fear stimuli.     

Contribution of X-ray computed tomography in the evaluation of kidney performance

X-ray computer assisted tomography scanner is an imaging method based on the use of X-ray attenuation in tissue. This attenuation is proportional to the density of the tissue (without or after contrast media injection) in each pixel image of the image. Spiral scanner, the electron beam computed tomography (EBCT) scanner and multidetector computed tomography scanner allow renal anatomical measurements, such as cortical and medullary volume, but also the measurement of renal functional parameters, such as regional renal perfusion, renal blood flow and glomerular filtration rate. These functional parameters are extracted from the modeling of the kinetics of the contrast media concentration in the vascular space and the renal tissue, using two main mathematical models (the gamma variate model and the Patlak model). Renal functional imaging allows measuring quantitative parameters on each kidney separately, in a non-invasive manner, providing significant opportunities in nephrology, both for experimental and clinical studies. However, this method uses contrast media that may alter renal function, thus limiting its use in patients with chronic renal failure. Moreover, the increase irradiation delivered to the patient with multi detector computed tomography (MDCT) should be considered.