Three-dimensional Volumetric Reconstruction Research Articles

The influence of age on greater sciatic notch morphology: testing the Walker method in an Australian population.

Sex estimation is an integral aspect of a forensic biological profile. The pelvis, being the most dimorphic part of the skeleton, has been studied in considerable detail relative to morphological and metric variation. However, empirical data on the effect of age on pelvic morphology relative to sex-specific morphological variation is limited, especially in regard to the estimation of skeletal sex. This study assesses whether there are age-related differences in the distribution of the Walker (2005) morphological scores for the greater sciatic notch (GSN) in an Australian population. Three-dimensional volumetric reconstructions derived from multi-detector computed tomography (MDCT) scans of 567 pelves of 258 females and 309 males aged 18 to 96years were scored following Walker (2005). Differences in score distributions and means by sex and age group were tested using Pearson's chi-squared test and ANOVA, respectively. The accuracy of sex estimates derived from logistic regression equations was explored using leave-one-out cross-validation. Significant differences were found in score distribution and means among age groups in females, but not in males. There was a tendency toward higher scores in older females. The overall sex estimation accuracy was 87.5%. When comparing age groups 18-49 and 70 + years, estimation accuracy decreased in females (99% vs. 91%), while the opposite was found for males (79% vs. 87%). These findings suggest that age affects GSN morphology. Higher mean scores in older females imply that, on average, the GSN becomes narrower with increasing age. It is thus recommended due consideration of estimated age when assessing sex based on the GSN in unidentified human remains.

A Putative Erythroid Synapse Linking Developing Erythroblasts and Macrophages in Erythroblastic Islands

An estimated 25% of the global population suffer from anemia, a major cause being deficient erythropoiesis. Mammalian erythropoiesis in the adult occurs primarily in the bone marrow (BM), with the spleen being an active site of extramedullary erythropoiesis during anemic stress. Here, we examine regulators of the anemic stress response using an unbiased transcriptomic approach to compare FACS-sorted splenic Ter-119+ erythroid precursors, from untreated mice or phenylhydrazine (PHZ)-treated mice exhibiting chemically-induced anemia. Transcriptomic analyses revealed unexpected expression of a broad range of immune markers in untreated mouse splenic erythroid cells, most which were conspicuously diminished in expression during PHZ-induced anemic stress. These surface antigens, previously unreported on erythroid cells, include markers of B lymphocytes (CD22, CD74), T lymphocytes (CD2, CD3ε) and leukocytes including CD11a/LFA-1, CD45, CD48, CD53, as well as the homing receptors L-selectin and PSGL-1. Immunophenotyping confirmed expression of these immune markers on a subpopulation of steady state BM and splenic erythroid precursors, with a significant reduction in immune marker-expressing erythroid cells seen in the spleen during anemic stress. Erythropoiesis is governed by a close relationship between erythroid precursors and central macrophages in multicellular clusters termed erythroblastic islands (EBIs). Confocal microscopy demonstrated localization of the immune markers CD2, CD3ε, CD11a and PSGL-1 on Ter-119+ mouse erythroid precursors with frequent clustering of markers seen at intercellular contact points where erythroid cells interact with the central EBI macrophage. PHZ-treated mice exhibited a significantly reduced frequency of EBIs in both the BM and spleen compared to control mice. PHZ-treated mice also demonstrated downregulated Interferon Regulatory Factor-8 (Irf8) transcripts on transcriptomic analysis of splenic erythroid precursors. Irf8-deficient mice have been reported to have a profoundly reduced erythroid compartment. There are also reports that Irf8 may be a regulator of macrophage morphology. We therefore studied Irf8-deficient mice to evaluate whether Irf8 has a role in EBI-regulation. BM analysis of Irf8-deficient mice showed a reduced frequency of EBI-like structures compared to wildtype (WT) mice. Scanning electron micrographs revealed that Irf8-/- macrophages are smaller with fewer erythroid precursors attached compared to WT macrophages. Irf8-/- EBIs harbored no identifiable reticulocytes in contrast to WT EBIs. EBI rosette reconstitution assays demonstrated that Irf8-/- erythroid precursors were unable to bind to WT or Irf8-/- macrophages, whereas Irf8-/- macrophages could interact with WT erythroid cells. Immunophenotyping of Irf8-/- erythroid precursors revealed that immune marker expression (CD2, CD38, CD43, CD45, PSGL-1) was significantly lower compared to WT counterparts. These data suggest that Irf8 may regulate both macrophage morphology and erythroid cell surface phenotype influencing erythropoiesis. The newly uncovered immune markers expressed by erythroid cells are also involved in formation of immunological synapses between lymphocytes and macrophages. This led us to question whether an analogous synapse-like structure may exist in EBIs. Serial block face scanning electron microscopy (SBF-SEM) was used to assess EBI morphology at the nanometer scale. SBF-SEM micrographs show erythroblasts extending pseudopods towards the macrophage for attachment. Three-dimensional volumetric reconstruction of SBF-SEM micrographs revealed en face spatial topologies present on the surface of EBI central macrophages similar to those seen in immunological synapses. Our findings suggest that immune markers, possibly mediated by Irf8, may function to form synaptic-like interactions between erythroid cells and macrophages that result in EBIs - an "erythroid synapse". Failure in forming these interactions may result in alterations in EBI formation with potential downstream impacts on erythropoiesis. Improved understanding of how EBIs form and function may aid in the development of therapeutic agents to combat anemia.

Pentalogy of Cantrell.

Pentalogy of Cantrell.

Three-dimensional polygonal muscle modelling and line of action estimation in living and extinct taxa

Biomechanical models and simulations of musculoskeletal function rely on accurate muscle parameters, such as muscle masses and lines of action, to estimate force production potential and moment arms. These parameters are often obtained through destructive techniques (i.e., dissection) in living taxa, frequently hindering the measurement of other relevant parameters from a single individual, thus making it necessary to combine multiple specimens and/or sources. Estimating these parameters in extinct taxa is even more challenging as soft tissues are rarely preserved in fossil taxa and the skeletal remains contain relatively little information about the size or exact path of a muscle. Here we describe a new protocol that facilitates the estimation of missing muscle parameters (i.e., muscle volume and path) for extant and extinct taxa. We created three-dimensional volumetric reconstructions for the hindlimb muscles of the extant Nile crocodile and extinct stem-archosaur Euparkeria, and the shoulder muscles of an extant gorilla to demonstrate the broad applicability of this methodology across living and extinct animal clades. Additionally, our method can be combined with surface geometry data digitally captured during dissection, thus facilitating downstream analyses. We evaluated the estimated muscle masses against physical measurements to test their accuracy in estimating missing parameters. Our estimated muscle masses generally compare favourably with segmented iodine-stained muscles and almost all fall within or close to the range of observed muscle masses, thus indicating that our estimates are reliable and the resulting lines of action calculated sufficiently accurately. This method has potential for diverse applications in evolutionary morphology and biomechanics.

In vivo human gracilis whole-muscle passive stress-sarcomere strain relationship.

We measured the passive mechanical properties of intact, living human gracilis muscles (n=11 individuals, 10 male and 1 female, age: 33±12 years, mass: 89±23 kg, height: 177±8 cm). Measurements were performed in patients undergoing surgery for free-functioning myocutaneous tissue transfer of the gracilis muscle to restore elbow flexion after brachial plexus injury. Whole-muscle force of the gracilis tendon was measured in four joint configurations (JC1-JC4) with a buckle force transducer placed at the distal tendon. Sarcomere length was also measured by biopsy from the proximal gracilis muscle. After the muscle was removed, a three-dimensional volumetric reconstruction of the muscle was created via photogrammetry. Muscle length from JC1 to JC4 increased by 3.3±1.0, 7.7±1.2, 10.5±1.3 and 13.4±1.2 cm, respectively, corresponding to 15%, 34%, 46% and 59% muscle fiber strain, respectively. Muscle volume and an average optimal fiber length of 23.1±0.7 cm yielded an average muscle physiological cross-sectional area of 6.8±0.7cm2 which is approximately 3 times that measured previously from cadaveric specimens. Absolute passive tension increased from 0.90±0.21N in JC1 to 16.50±2.64N in JC4. As expected, sarcomere length also increased from 3.24±0.08 µm at JC1 to 3.63±0.07 µm at JC4, which are on the descending limb of the human sarcomere length-tension curve. Peak passive muscle stress was 27.8±5.5 kPa in JC4 and muscle modulus ranged from 44.8 MPa in JC1 to 125.7 MPa in JC4. Comparison with other mammalian species indicates that human muscle passive mechanical properties are more similar to rodent muscle than to rabbit muscle. These data provide direct measurements of whole-human muscle passive mechanical properties that can be used in modeling studies and for understanding comparative passive mechanical properties among mammalian muscles.

Flexible Assemblies of Electrocapacitive Volume Tomographic Sensors for Gauging Fuel of Spacecraft

Gauging propellant fuel of spacecraft in outer space has been an issue, because their liquid fuels tend to float, slosh, adhere to the tank walls, and form bubbles under low-gravity conditions. For this reason, conventional fuel gauging techniques may not be an accurate way of gauging the fuel in space. In this paper, we report a flexible monolithic printed assembly of electrocapacitive volume tomography sensors, which can reconstruct the three-dimensional shape of the propellant fuel and promise to overcome the deficiencies of conventional fuel-gauging techniques. A commercial printer was used to transfer the patterns of the electrocapacitive volume tomography sensors and electric connections onto a flexible laminated copper. Feasibility of the three-dimensional volumetric reconstruction on water and a heat-transfer fluid showed that the National Institute of Standards and Technology’s flexible electrocapacitive volume tomography sensor system could successfully sense the changes in electrocapacitance due to the presence of these liquids. Based on those measured electrocapacitive volume tomography data, the three-dimensional shape of the fluid was reconstructed and matched with the real one used during laboratory testing.

109. Radiographic predictors of indirect neural decompression in minimally invasive transpsoas lateral interbody fusion

BACKGROUND CONTEXT An advantage of lateral interbody fusion (LLIF) surgery is the resultant indirect decompression of the neural elements that occurs with disc height restoration, restoration of spinal alignment and ligamentotaxis. The degree to which indirect decompression of the spinal canal occurs varies patient to patient, and there remains no method for effectively predicting which patients will or will not respond. PURPOSE In this study, we identify pre- and postoperative predictive factors of radiographic indirect decompression of the central spinal canal. The goal is to help surgeons ascertain which patients best respond to indirect decompression in the setting of lateral interbody fusion. STUDY DESIGN/SETTING This is a retrospective evaluation of a prospectively and consecutively collected cohort of patients treated for degenerative etiologies at a single institution. PATIENT SAMPLE Patients were included if they received a minimally invasive lateral transpsoas interbody fusion by a single surgeon at our institution. Patients were treated for degenerative etiologies. OUTCOME MEASURES A retrospective evaluation of prospectively collected consecutive patients treated with LLIF surgery treated at a single institution without subsequent direct decompression was performed. Pre- and postoperative MRI imaging was used to grade canal stenosis and three-dimensional volumetric reconstructions were used to measure changes in the central canal area (CCA). METHODS Multivariate regression was used to identify predictive variables that correlated with increases in CCA. Independent assessments of canal measurements were made by a blinded board-certified neuroradiologist and a spine surgeon. RESULTS Sixty-six patients with 110 levels were treated with a mean age of 68 years. Forty-six levels (42%) were treated for DDD, 36 levels (33%) for spondylolisthesis, 11 levels (10%) for adjacent segment disease and 17 levels (15%) for deformity. Preoperatively, 19 patients had moderate (29%) and 18 had severe stenosis (27%) with the remainder having mild or no stenosis. Of these 37 patients, only 4 remained severe, 4 were moderate and the rest (78%) improved to mild or no stenosis. CCA increased 41% from a mean of 1.09 to 1.55 cm2 (p 0.05). Multivariate evaluation of predictive variables identified that preoperative anterolisthesis (p=0.002), the presence of vacuum disc phenomenon (p=0.049) and preoperative segmental lordosis (p=0.009) were independently associated with percentage increase in CCA. Age, body mass index, side of approach, pedicle screw fixation, facet grading score, presence of facet effusions, preoperative anterior and posterior disc heights, implant distance from the posterior aspect of the vertebral body and implant height all were not associated (p>0.05). CONCLUSIONS LLIF successfully achieves indirect decompression of the CCA radiographically with a mean change of 41%. Preoperative anterolisthesis on standing films, the presence of vacuum disc phenomenon on computed tomography and preoperative segmental lordosis were independently predictive factors for the percentage increase in CCA that can be achieved. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs.

Three-Dimensional Volumetric Renal Reconstruction Based on Geometrical Coefficients.

The article presents an innovative method of 3D computer tomography (CT) image reconstruction of kidney. Diagnosis based on CT scanning allows to obtain projections of multi-dimensional object, made from different directions in order to create cross-sectional (2D) slices. Standard techniques for identifying kidneys in CT images analyze each 2D slice separately. It causes different reconstruction accuracy for the same object at its different heights. This is the main problem of a machine-learning systems. Reconstruction error of end-slices of the kidney model is often greater than the error of the kidney's middle part. The main idea of the technique presented in this paper is to analyze the largest coherent 3D spatial-areas. This technique allows to increase the accuracy of kidney detection as well as to decrease the FP (false positive) error. An additional advantage of the developed algorithm is the possibility of obtaining a precise model representing the 3D view of an entire kidney.

The Tail of the Late Jurassic Sauropod Giraffatitan brancai: Digital Reconstruction of Its Epaxial and Hypaxial Musculature, and Implications for Tail Biomechanics

Dinosaur locomotion and biomechanics, especially of their pelvic girdles and hind limbs, have been analysed in numerous studies. However, detailed volumetric musculoskeletal models of their tails are rarely developed. Here, we present the first detailed three-dimensional volumetric reconstruction of the caudal epaxial and hypaxial musculature of the Late Jurassic sauropod Giraffatitan brancai, and highlight the importance and necessity of 3D modelling in musculoskeletal reconstructions. The tail of this basal macronarian is relatively short compared to diplodocids and other coexisting macronarians. The centre of mass lies well in front of the hind limbs, which support only ca. half the body weight. Still, our reconstruction suggests a total weight for the entire tail of ca. 2500 kg. We conclude that the hypaxial and hind limb muscles (more specifically the M. caudofemoralis longus and its counterpart the M. ilioischiocaudalis) in Giraffatitan were well developed and robustly built, compensating for the shorter length of the M. caufodemoralis longus, the main hind limb retractor muscle, in comparison with other sauropods. Our methodology allows a better-constrained reconstruction of muscle volumes and masses, in extinct taxa, and thus force and weight distributions, throughout the tail, than non-volumetric approaches.

Three-Dimensional CT Morphometric Image Analysis of the Clivus and Sphenoid Sinus in Chiari Malformation Type I.

This study evaluated three-dimensional (3D) volumetric image reconstructions to identify morphological differences of the clivus and sphenoid sinus on computed tomography (CT) scans of Chiari malformation type I (CMI) and control subjects. Axial CT imagesof adult females for 30 CMI subjects and 30 age and body mass index (BMI) matched controls were used for this retrospective study. 3D volumetric reconstructions were created from the bone windows of axial data following image registration for position and orientation correction of the head. The volume, surface area, linear dimensions and spatial position in the x, y, and z-axes were computed separately for the clivus and the sphenoid sinus for each subject. Eleven parameters were found to be significantly different between CMI subjects compared to controls. Most notably, clivus volume was reduced by 31% on average in CMI subjects. In contrast, we found that the sphenoid sinus volume was 38% greater on average in CMI subjects. Moreover, clivus length, height, width, and thickness were 3.7, 2.8, 3.0 and 9.4mm reduced, respectively, in CMI subjects. This is the first study to demonstrate cephalometric differences in the 3D morphology of the clivus and sphenoid sinus between CMI subjects and controls.

ULTRASOUND EXAMINATION POSSIBILITIES IN ADENOMYOSIS DIAGNOSTICS IN PATIENTS WITH REPRODUCTIVE LOSS

Aim.The research was designed to study the possibilities of ultrasound examination with Color Doppler imaging (CDI) and three-dimensional volumetric reconstruction (3D) in the diagnostics of adenomyosis of minimal prevalence in patients with unspecified infertility and reproductive losses at the early stages of gestation.Materials and methods.40 patients with unspecified infertility and early pregnancy loss (the main group) and 35 healthy patients (the control group) were examined in the course of the study. All patients underwent small pelvic ultrasound in В / CDI / 3D-modes with an assessment of the junctional zone (JZ) on days 5-7 and 18-22 of the menstrual cycle (MC).Results.In the main group, there was a discrepancy between the structure of the endometrium and the phase of the cycle at 5-7 days of the MC, a decrease in vascularization of the JZ at 18-22 days of the MC, a local increase in blood flow in the endometrium in phases 1 and 2 of the MC; the fuzziness of the junctional zone, an increase in min and max thickness of the junctional zone, the difference between them, as well as the ratio of max thickness of the junctional zone to the thickness of the uterus wall regardless of the phase of the MC (p = 0.005; 0.0001; 0.005; 0.03; 0.0004; 0, 0001; 0.0001; 0.0001; 0.0001 respectively).Conclusion.Ultrasonography with the CDI and 3D reconstruction allows us to identify a high-risk group by the presence of a minimal prevalence of adenomyosis in the patients with unspecified infertility and reproductive losses at the early stages of gestation.

Usefulness of preoperative three-dimensional volumetric analysis of carotid body tumors.

The Shamblin classification is the commonest method to predict complications and outcomes during carotid body tumor (CBT) resection. The aim of this study is to describe the utility of the three-dimensional volumetric reconstruction (3DVR) analysis of the CBT and its relationship with postoperative outcomes. Preoperative computed tomography angiography (CTA) was obtained to perform 3DVR of the CBT. Imaging data were analyzed and correlated with surgical outcomes: estimated blood loss (EBL), surgical time (ST), and hospital length of stay (HLOS). The Pearson test was used to determine the correlation between volume and postoperative outcomes. Fifty-seven patients were studied, 13 had Shamblin type I tumors with a mean 3DVR of 7.69cm3 (standard deviation [SD 8.27]), 21 were type II with a mean 3DVR of 15.57cm3 (SD 8.40), and 23 were type III with a mean 3DVR of 30.58cm3 (SD 20.16). EBL mean was 559milliliters (mL) (standard error [SE] 80.44), the mean ST of resection was 202min (SD 67), and the mean HLOS was 5.8days (SD 3.23). The Pearson test showed a correlation of r = 0.69 (p < 0.0001) between 3DVR and EBL, a r = 0.4 (p = 0.05) was obtained between 3DVR and ST, and finally, a r = 0.3 (p = 0.05) between 3DVR and HLOS was obtained. The preoperative 3DVR determination of CBTs allows to analyze possible predictors of surgical outcomes. We found a positive correlation between the 3DVR volume and EBL. Further research is necessary to validate this method in the evaluation of these rare neoplasms.

X-ray microtomography system for small and light samples using a flat panel detector.

A low-cost system able to perform microtomography of samples such as teeth, insects, or other small materials and low atomic numbers is presented. For this, a small flat panel type sensor was used. The process of characterization of the detector is detailed, as well as its main characteristics. The electromechanical control and the software used are also described. The advantages, some limitations, and comparisons with commercial systems are presented along with some three-dimensional volumetric reconstruction of different materials that served as samples during the development of the system.

Relationship between Lung Volume and Pulmonary Function in Patients With Adolescent Idiopathic Scoliosis: Computed Tomographic-based 3-Dimensional Volumetric Reconstruction of Lung Parenchyma.

Retrospective. We determined values for the volume of right lung (Vr), left lung (Vl), total lung volume (Vt), and left/right lung volume ratio (Vl/Vr), allowing comparison between those data measured and those of age-matched controls. To find whether lung volume correlates with preoperative pulmonary function. To our knowledge, no study on relationship between computed tomographic (CT) scans determined lung volume and pulmonary function test (PFT) in scoliosis have been published. All examinations with PFT (31 cases) were identified. Three-dimensional volumetric reconstruction of lung parenchyma was performed on existing preoperative CT scans for 26 idiopathic scoliosis patients. Vl, Vr, Vt, Vl/Vr, and absolute value of right volume minus left volume (|Vr-Vl|) were calculated and correlated with PFTs. To determine if significant difference of preoperative lung volume exists between idiopathic scoliosis patients and controls. Linear regression models, using 3-dimensional lung volume parameters as predictors for vital capacity (VC), forced vital capacity (FVC), and total lung capacity (TLC), were created. Vt was positively correlated with VC, FVC, forced expiratory volume in 1 second (FEV1), TLC, predicted value for FVC (FVC%), predicted value for FEV1 (FEV1%), predicted value for TLC (TLC%), and predicted value for maximal ventilator volume (MVV%) (P<0.05); |Vr-Vl| was not correlated with ventilation parameters (P>0.05); Diffusion parameters were not correlated with CT-reconstructed lung volume parameters (P>0.05); male and female adolescent idiopathic scoliosis patients had less Vt, Vr, and Vl compared with those of age-matched controls (P<0.05). Vt was positively correlated with VC, FVC, FEV1, TLC, FVC%, FEV1%, TLC%, and MVV%. Vt, Vr, and Vl of adolescent idiopathic scoliosis patients were less than those of age-matched controls.

Quantitative Evaluation of Adult Subglottic Stenosis Using Intraoperative Long-range Optical Coherence Tomography.

To determine the feasibility of long-range optical coherence tomography (LR-OCT) as a tool to intraoperatively image and measure the subglottis and trachea during suspension microlaryngoscopy before and after endoscopic treatment of subglottic stenosis (SGS). Long-range optical coherence tomography of the adult subglottis and trachea was performed during suspension microlaryngoscopy before and after endoscopic treatment for SGS. The anteroposterior and transverse diameters, cross-sectional area (CSA), distance from the vocal cords, and length of the SGS were measured using a MATLAB software. Pre-intervention and postintervention airway dimensions were compared. Three-dimensional volumetric airway reconstructions were generated using medical image processing software (MIMICS). Intraoperative LR-OCT imaging was performed in 3 patients undergoing endoscopic management of SGS. Statistically significant differences in mean anteroposterior diameter (P < .01), transverse diameter (P < .001), and CSA (P < .001) were noted between pre-intervention and postintervention data. Three-dimensional airway models were viewed in cross-sectional format and via virtual "fly through" bronchoscopy. This is the first report of intraoperative LR-OCT of the subglottic and tracheal airway before and after surgical management of SGS in humans. Long-range optical coherence tomography offers a practical means to measure the dimensions of SGS and acquire objective data on the response to endoscopic treatment of SGS.

Perspectivas futuras na tomografia de coerência óptica

The rapid development of optical coherence tomography (OCT) and its ophthalmic applications has resulted in new systems that vary in performance and functionality providing in vivo three-dimensional volumetric reconstructions of both anterior and posterior segments of the human eye within unimaginable speed. Newer swept source OCT systems have made it possible to achieve OCT acquisition speeds of several million A-scans/s. Another direction of OCT development includes the introduction of adaptive optics to imaging of the posterior segment of the eye that allows correction of the eye’s static and dynamic aberrations, resulting in the achievement of volumetric cellular resolution retinal imaging. The purpose of this article is to present the various aspects of the development of OCT technology within the context of its ophthalmic applications, as well as, the impact of functional OCT.

Total anomalous connection of pulmonary veins to the portal vein. Value of multislice angiotomography. Report on three cases

Objective: Present tomographic data from the patients with emphasis on structural characteristics. Material and method: Retrospective study of three patients in whom the four pulmonary veins connected to the portal vein. This malformation is one of the varieties of total anomalous connection of pulmonary veins. In any of them, the pulmonary veins do not connect to the left atrium and blood from the lung reaches the right atrium directly or through its tributary systems. In such cases, arterialized pulmonary blood and systemic venous blood mix at the site of the anomalous connection and a short circuit is formed from the right atrium to the left atrium through an interauricular communication, allowing patients to survive. Total anomalous connection of pulmonary veins accounts for between 0.4 and 2.0% of congenital heart diseases: it occurs in 6.8 of every 100,000 individuals. It is diagnosed in 68% of patients in neonatal stage, which reflects the severity of the condition. The infracardiac variety of total anomalous connection of pulmonary veins accounts for between 15 and 26% if all its varieties. Multislice angiotomography allows us to view the blood vessels and adjacent organs under consideration and obtain high-definition anatomic information. In the patients in this study, total anomalous connection of pulmonary veins to the portal vein was viewed with three-dimensional volumetric tomographic reconstructions and their correlation with ultrasonography studies.

Three-dimensional temporal bone reconstruction from histological sections.

To produce a high-resolution, three-dimensional temporal bone model from serial sections, using a personal computer. Digital images were acquired from histological sections of the temporal bone. Image registration, segmentation and three-dimensional volumetric reconstruction were performed using a personal computer. The model was assessed for anatomical accuracy and interactivity by otologists. An accurate, high-resolution, three-dimensional model of the temporal bone was produced, containing structures relevant to otological surgery. The facial nerve, labyrinth, internal carotid artery, jugular bulb and all of the ossicles were seen (including the stapes footplate), together with the internal and external auditory meati. Some projections also showed the chorda tympani nerve. A high-resolution, three-dimensional computer model of the complete temporal bone was produced using a personal computer. Because of the increasing difficulty in procuring cadaveric bones, this model could be a useful adjunct for training.

Intramuscular Technique for Gluteal Augmentation

New surgical techniques for gluteal augmentation have improved final results. It is estimated that more than 35,000 patients have undergone augmentation gluteoplasty using implants. The authors sought to determine and quantify the presence of muscle atrophy, and to evaluate implant positioning using the intramuscular technique. Twenty-three female patients were selected prospectively for this study and underwent intramuscular gluteal augmentation using gluteal implants of a round or oval base. Computed tomographic scanning and three-dimensional volumetric reconstruction were used to investigate muscle atrophy and implant position, with comparison of the results between the preoperative scan and scans obtained 3, 6, and 12 months after surgery. Three-dimensional reconstruction and volumetric analysis showed muscular atrophy. After 12 months of follow-up, 34 gluteal muscles (17 patients) were analyzed, with 4.3 percent atrophy remaining on the right side and 2.6 percent on the left side. Twenty-three patients were studied regarding position (46 gluteal implants). All oval base implants introduced in a vertical direction (seven patients) turned to an oblique direction, following the direction of muscle fibers by 3 months after surgery. Two patients showed rotation of the implant. The presence of a gluteal implant caused muscle atrophy. However, it did not lead to clinical or physical limitations. It is not important whether the implants are positioned vertically or obliquely, provided that they are symmetric. The technique proved to be safe in maintaining the intramuscular position of the implant, with good satisfaction for the patients. Therapeutic, IV.

Results and error analysis of a reference voxel normalization method for neutron computed tomography partial volume voxel water quantification

Although water quantification using neutron imaging has been successfully applied to water distribution studies of hydrogen-powered fuel cells, the technique produces two-dimensional images, which makes it difficult to determine the exact “depth” inside of an object where an imaged mass of water is located. In contrast, neutron computed tomography (NCT) is an imaging technique that generates a three-dimensional volumetric reconstruction of an object’s interior geometry, allowing determination of a structure’s exact spatial location. In a reconstruction, determination of the fractional water masses present in partial volume voxels is required for an accurate quantification. Such a NCT partial volume voxel water quantification technique has been developed at The Pennsylvania State University Radiation Science and Engineering Center (RSEC). Several approaches with water-filled cylindrical aluminum samples were used to test the technique: MCNP simulations, samples 30mm from the detector, and samples 140mm from the detector. Quantification results were within 0.2% of the theoretical for the MCNP simulations and within 2% for the samples 30mm from the detector. Significant error, as large as 47%, was seen with the samples 140mm from the detector. Geometric un-sharpness was determined to be the dominant source of this error. Comparisons between capturing a full set of projections, called true-CT, and a single projection that is duplicated to approximate a full set, called pseudo-CT, were also performed. Results showed pseudo-CT well approximated true-CT, within 1%, for a sample with geometry simple enough that its attenuation map was the same for every viewing angle.