High-resolution Computed Tomography Data Research Articles

Abstract P2-05-01: A Comparative Study of 18F-Fluoride PET/CT and Whole-Body High Resolution CT (HRCT) for the Detection of Bone Metastases in Patients with Advanced Breast Cancer

Abstract Background: Bone scintigraphy (BS) have been shown to be of value in detecting bone metastases several months before conventional radiography, whereas computed tomography (HRCT) and magnetic resonance imaging (MRI) can reveal more metastases in the spine than conventional BS. 18F-Fluoride PET has been shown to be more accurate than BS for the detection bone lesions in different malignancies and has been suggested as an alternative to BS. Recent studies have shown that integrated 18F-Fluoride-PET/CT is both sensitive and specific for detection of lytic and sclerotic lesions and is superior to 18F-Fluoride PET. The aim of our study is to evaluate the diagnostic accuracy of 18F-Fluoride-PET/CT in comparison to HRCT for the detection of bone metastases in breast cancer patients. Material and methods: The study involved 39 patients with breast cancer with known bone metastases or at high risk for its presence. All patients presented indications for skeletal surveys. Imaging was performed on an integrated PET/CT system. All PET scans were acquired in 2D mode and were reconstructed using an iterative reconstruction algorithm; diagnostic HRCT data of PET/CT were acquired for detecting bone lesions and were used for attenuation correction. PET acquisition started 60 min after intravenous injection of 370-550 MBq 18F-labelled NaF and included 10-12 bed positions. The interpretation of PET/CT and High resolution CT studies was made as a consensus reading of two nuclear medicine physicians and a radiologist who had access to clinical, as well as previous radiological imaging information. 12 months follow-up based on previous and/or following imaging studies was considered the gold standard. Results: Overall 671 bone lesions were detected in our analysis including both PET/CT and CT results. Of these lesions 530 malignant, 32 equivocal and 109 benign were classified by consensus reading. 18F-Fluoride PET/CT detected 491 bone metastases, 114 (23%) of which without any clear morphological changes on CT. HRCT detected 416 bone metastases, 39 (9.3%) of which without any 18F-fluoride uptake. The overall sensitivity and specificity was 90% and 91% for 18F-Fluoride-PET/CT and 79 and 93% for HRCT, respectively. In a patients based analysis both 18F-Fluoride-PET/CT and HRCT identified the same number of patients with bone metastases (27 of 39). Conclusions: Our data show a high agreement (71% of lesions and 100% of the patients) between 18F-Fluoride-PET/CT and HRCT for bone metastases detection. However integrated analysis of 18F-Fluoride-PET/HRCT has the best diagnostic option to evaluate bone involvement in breast cancer, and 18F-Fluoride-PET/CT seems to have the highest sensitivity. Follow-up is ongoing to assess the prognostic/predictive value of 18F-Fluoride-PET/CT. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P2-05-01.

Analysis of correlation between congenital auricular deformities and middle ear malformations

To explore the potential value of knowing the relationship between congenital auricular deformities and middle ear malformations. A total of 86 patients with congenital auricular deformities and middle ear malformations, including 51 males and 35 females, were admitted from January 2008 to December 2009 to the Eye Ear Nose and Throat Hospital of Fudan University. Fifty-eight patients had unilateral deformities (R:L = 34:24), while 28 were bilateral. One hundred and fourteen ears with congenital auricular deformities were included. High-resolution CT (HRCT) data was obtained from each patient. The auricular deformities were classified into three grades using the Marx H classification system. The modified Jahrsdoerfer grading system was used to score the malformations using HRCT data. The correlation between the grades of auricular deformities and scores of middle ear malformations was analyzed using Spearman rank correlation analysis. The Marx H grades of congenital auricular deformities were 12 patients with grade I, 25 patients with grade II and 77 patients with grade III, while their corresponding Jahrsdoerfer scores were 7.8 ± 2.4, 6.8 ± 2.6 and 6.0 ± 2.8, respectively. The statistical analysis suggested a trend of negative correlation between the Marx H grades of auricular deformities and the Jahrsdoerfer scores of middle ear malformations (r = -0.2386, P = 0.0106). There was a trend to a negative correlation between congenital auricular deformities and middle ear malformations.

SCLERODERMA SYSTEMATICA WITH INTERSTITIAL LUNG LESION: COMPARATIVE CLINICAL CHARACTERISTICSWITH PATIENTS WITHOUT LUNG LESION

Система комплексной поддержки и сопровождения научного журнала Elpub позволяет запустить двуязычный сайт журнала со встроенной системой электронной редакции в соответствии с лучшими издательскими практиками, а так же предусматривает техническую и методическую поддержку со стороны специалистов НЭИКОН.

Clinical and HRCT screening of heavily asbestos-exposed workers

To characterize asbestosis today and to clarify the indications for high-resolution computed tomography (HRCT) in the surveillance of heavily exposed workers. Six hundred and twenty-seven workers were screened and HRCT findings were classified and divided in two groups: pulmonary fibrosis (n = 86) and no fibrosis (n = 541). Most (65/86 = 76%) of the detected fibrosis cases were mild. The magnitude of asbestos exposure showed an unexpected inverse relation with fibrosis. In multivariate analyses, age, forced expiratory volume in 1 s/forced vital capacity ratio, and poor diffusing capacity were associated with HRCT fibrosis, but asbestos exposure was not. Asbestosis seems to be characterized by mild fibrosis today even in heavily exposed workers. To avoid radiation exposure in HRCT, age and lung function data may be used only to a limited extent to select imaging candidates. Selection and recollection biases may distort the relation between asbestos exposure and fibrosis.

From high-resolution CT data to finite element models: development of an integrated modular framework

New ideas for the extraction of finite element (FE) models from high-resolution computed tomography datasets are presented. The multi-step approach starts with a 3D region-growing algorithm in order to extract the outer voxel based iso-surface. This information is used to compute a voxel model of the cortical shell. The next step provides triangulated surfaces of the outer bone contour. Three-dimensional deformable models using a gradient vector flow and a multi-level mesh resampling are used. These meshes are self-regularising and of high quality. A further step contains a new self correcting cortical shell thickness evaluation algorithm, which results in topological conform smooth inner and outer compact bone iso-surface meshes. Such iso-surfaces can be used for numerically efficient FE models, which are of bio-mechanical and clinical importance. Details of the approach are described and applications with respect to a human proximal femur and vertebral body are shown.

A comparison of enhanced continuum FE with micro FE models of human vertebral bodies

Continuum finite element (FE) models are standard tools for determination of biomechanical properties of bones and bone-implant systems. This study investigates the accuracy of an enhanced continuum FE model by taking μ FE as the gold standard. The enhanced continuum models account for trabecular bone morphology (density and fabric) as well as for an anatomically correct cortical shell. Vertebral body slice models are extracted from high-resolution CT images using an algorithm proposed in [Pahr and Zysset, 2008b. From high-resolution CT data to FE models: development of an integrated modular framework. Computer Methods in Biomechanics and Biomedical Engineering, in press.]. Three different models are generated: the proposed enhanced density-fabric-based model with a subject-specific cortex and two classical isotropic density-only models, with and without explicit modeling of the cortical shell. The material property errors of the used morphology-elasticity relationship are minimized by using elasticity tensors from 60 cubical μ FE models which are cropped from the trabecular centrums of the investigated vertebral bodies. Two different boundary conditions—kinematic [ Van Rietbergen et al., 1995. A new method to determine trabecular bone elastic properties and loading using micromechanical FE models. Journal of Biomechanics 28 (1), 69–81] and mixed [Pahr, D.H., Zysset, P.K., 2008a. Influence of boundary conditions on computed apparent elastic properties of cancellous bone. Biomechanics and Modeling in Mechanobiology 7, 463–476.]—are used in these FE models. After removal of the endplates, compressive and antero–posterior shear loading is applied on the investigated vertebral bodies. Individual error sources are studied in more detail by loading also the trabecular centrum (removed shell) and the cortical shell alone. It is found that the cortex-only models need a correction of the shell thickness when transforming from a voxel to a smooth description. The trabecular centrum alone gives too stiff and too soft a response using material calibration with kinematic and mixed boundary conditions, respectively. A comparison of the whole vertebral body stiffnesses shows that an orthotropic cancellous bone material calibrated with kinematic boundary conditions corresponds best with μ FE . Taken together, the proposed enhanced homogenized surface-based FE model is structurally more accurate than density-only models.

Pleural plaques and asbestosis: dose- and time-response relationships based on HRCT data

Most studies on asbestos-related diseases are based on chest radiographs, and dose-response relationships are still controversial. The aim of this study was to describe the most relevant parameters of asbestos exposure linked to pleural plaques and asbestosis diagnosed by high-resolution computed tomography (HRCT). A large screening programme including systematic HRCT examinations was organised from 2003 to 2005 in France for formerly asbestos-exposed workers. The time since first exposure (TSFE), level, duration and cumulative exposure to asbestos were used in adjusted unconditional logistic regression to model the relationships of the two diseases. Analysis of a population of 5,545 subjects demonstrated that TSFE (p<0.0001) and cumulative exposure (p = 0.02) (or level, depending on the models used), were independently associated with the frequency of pleural plaques. Only cumulative exposure (p<0.0001) or level of exposure (p = 0.02) were significantly associated with asbestosis. All trend tests were significant for these parameters. To date and to our knowledge, this study is the largest programme based on HRCT for the screening of asbestos-exposed subjects. Both time-response and dose-response relationships were demonstrated for pleural plaques, while only dose-response relationships were demonstrated for asbestosis. These parameters must be included in the definition of high-risk populations for HRCT-based screening programmes.

A Descriptive Study of Non-Cystic Fibrosis Bronchiectasis in a Pediatric Population from Central and Southern Italy

Background: Non-cystic fibrosis (CF) bronchiectasis is now identified more often than in the past. Objectives: It was the aim of this study to assess the high-resolution computed tomography (HRCT) localization and extent of bronchiectasis and to determine whether asthma status, atopy and bronchiectasis distribution are associated with the etiology of bronchiectasis. Methods: We retrospectively analyzed clinical, laboratory, functional and HRCT data of 105 children with non-CF bronchiectasis at 2 tertiary respiratory units in Italy. Forty cases had bronchiectasis associated with ongoing underlying conditions, namely primary ciliary dyskinesia, primary immunodeficiency or aspiration. Results: Age at the onset of chronic cough/wheeze and at the first X-ray-documented pneumonia as well as atopy prevalence were lower in patients with ongoing underlying conditions than in those without (p = 0.049, p = 0.003 and p = 0.0008, respectively). In most cases, bronchiectasis was multilobar, and a mean of 2.5 lobes were involved. The right side was more often involved than the left (88 vs. 70%; p = 0.002), and the upper lobes were relatively spared (p < 0.000001). Right lung involvement and multilobar disease were more prevalent in children younger than 2 years at first pneumonia (p < 0.05). Conclusions: Clinical information combined with laboratory data provides additional insights into the characteristics of non-CF bronchiectasis in a large population of Italian children. This study highlights the need for longitudinal evaluations, also using HRCT, of severe and non-resolving pneumonia in children.

SU‐GG‐I‐96: Improvements for Fully Automatic Lung Segmentation From RT Planning Scans

Purpose: Segmentation of pulmonary X‐ray computed tomography (CT) images is a primordial step to most pulmonary image analysis applications. Many approaches have been presented in the past mainly focusing on lung extraction from high resolution CT data. Looking towards RT planning one has often to deal with low image quality, artifacts and pathological changes of the anatomy. We present a fully automatic method for delineation of the lungs and the trachea in three‐dimensional RT planning scans for thorax and breast patients. Method and Materials: The method consists of several steps. First, lung region is extracted automatically computing an optimal threshold method. Then, the trachea is separated from the lungs by fast marching. Next left and right lungs are separated in each slice by computing a minimal path in the area where separation is suspected from the information of the neighboring slices. Finally the 3D segmentations of the left and right lungs are refined running the random walker algorithm with foreground and background seeds automatically calculated from the intensity‐based pre‐segmentation. Results: Processing time is below one minute and does not require any user input. Several 3D CT Datasets from different patients were used to evaluate the methods. The algorithms can segment the trachea and separate the left and right lung. In comparison to previous publications stability could be improved. Still in some cases result are not satisfying, e.g. trachea segmentation reaches into the lungs and lesions or emphysema are not included in the lung segmentations. Conclusion: The presented algorithm allows for fully automatic lung segmentation. One major improvement could be to employ a shape model as recently published by other groups as a shape‐constrained segmentation method could help to overcome the observed problems with exclusion of pathologies.

Computed Tomography Findings in Acute Exacerbation of Idiopathic Pulmonary Fibrosis

The serial computed tomography findings and prognosis of the acute exacerbation of idiopathic pulmonary fibrosis (IPF) are not yet well defined in a larger number of cases. To evaluate the parenchymal abnormalities and prognosis using high-resolution computed tomography (HRCT) in acute exacerbation of IPF. The study consisted of clinical, laboratory, and HRCT data before and at the time of acute exacerbation in 64 episodes of 58 patients with IPF. A semiquantitative analysis of overall extent of parenchymal abnormalities, extent of alveolar opacity (ground-glass attenuation and consolidation), and extent of fibrotic opacity (reticulation and honeycombing) on CT was performed by two chest radiologists. The newly appeared parenchymal abnormalities were also classified into three patterns: peripheral, multifocal, and diffuse. In all patients, HRCT scans taken at the exacerbation showed typical signs of IPF and newly developing alveolar opacity. They included 34 patients of peripheral pattern, 8 of multifocal pattern, and 16 of diffuse pattern. Twenty-five patients died and 33 survived after the initial exacerbation. Worse survival was associated with patients with diffuse type compared with patients with multifocal and peripheral type. The CT patterns and overall CT extent were associated with an increased hazard of death after adjusting for age, sex, smoking, baseline diffusion capacity for carbon monoxide, baseline FVC, and disease extent on CT. On multivariate analysis, the strongest correlations were observed between CT patterns (combined diffuse and multifocal versus peripheral) and survival (odds ratio, 4.629; 95% confidence interval, 1.900-11.278; P = 0.001). HRCT extent and patterns are predictive of survival in acute exacerbation of IPF.

Mathematical analysis of DICOM CT datasets: Can endograft sizing be automated for complex anatomy?

To validate the use of a novel mathematical algorithm applied to digital imaging and communication in medicine (DICOM) computed tomography (CT) data to automate the generation of complex endovascular graft planning. An algorithm was developed enabling the creation of patient-specific mathematical model based upon DICOM CT data to allow for detailed efficient geometric analysis with repeatable results. This algorithm was applied to high resolution DICOM CT datasets of 15 patients, selected at random from 350 patients with aneurysms involving the visceral arteries. The longitudinal and rotational relationships of the visceral vessels were determined by the algorithm. For comparison purposes, the same measurements were acquired manually using centerline of flow software by a blinded investigator. The distance between the renal arteries, and location of the renal origins calculated with each method were then compared. Automated results were readily created for all 15 randomly selected patients. The measured versus calculated mean inter-renal artery distances were exceptionally close, differing by a mean of only 1.3 mm with a maximal range of 3.0 mm. The rotational position of the renal origins differed by only 10.5 degrees of arc (21 clock-face minutes) on average and by 32.5 degrees in the worst case. The generation of an automated mathematical model to represent complex aortic geometry is feasible and reproducible in the context of high-resolution CT data. This process has been validated in 15 patients, where results corresponded with manual measurements that were used to successfully implant customized devices that accommodate the imaged vessels. Additional attributes include the expression of the 3D aorta in a compact form (on the order of kilobytes) for purposes of data storage, transfer, and other manipulations. The construct of mathematical representation of patient specific anatomy from CT data is both feasible and applicable, allowing for automated endograft device design even in the setting of markedly tortuous anatomy where the repair must incorporate major aortic branches. The process has been validated in 15 patients, where results corresponded with manual measurements that were used to successfully implant customized devices that accommodate the imaged vessels. The application of this technology must now be studied in a prospective manner and incorporated into a system users may readily apply to patients undergoing evaluation. Additional attributes of a mathematical representation of the arterial tree include the 3D expression from a very compact set of parameters (on the order of kilobytes) for purposes of data storage, transfer, and other manipulations.

Modeling Real-Time 3-D Lung Deformations for Medical Visualization

In this paper, we propose a physics-based and physiology-based approach for modeling real-time deformations of 3-D high-resolution polygonal lung models obtained from high-resolution computed tomography (HRCT) images of normal human subjects. The physics-based deformation operator is nonsymmetric, which accounts for the heterogeneous elastic properties of the lung tissue and spatial-dynamic flow properties of the air. An iterative approach is used to estimate the deformation with the deformation operator initialized based on the regional alveolar expandability, a key physiology-based parameter. The force applied on each surface node is based on the airflow pattern inside the lungs, which is known to be based on the orientation of the human subject. The validation of lung dynamics is done by resimulating the lung deformation and comparing it with HRCT data and computing force applied on each node derived from a 4-D HRCT dataset of a normal human subject using the proposed deformation operator and verifying its gradient with the orientation.

2007 Annual Meeting of the National Lung Cancer Partnership: A Summary of Meeting Highlights

This report presents highlights from The National Lung Cancer Partnership's Annual Meeting, held in June 2007 in Chicago. It discusses recent refinements in the histologic, genetic, and epigenetic subtyping of lung cancers and suggests reasons why certain therapies benefit only a subset of lung cancer patients. It also describes new molecular data about the subtype-specific differences in drug resistance among bronchioloalveolar-associated non-small cell lung cancers and discusses strategies to avoid or tackle specific drug-resistant tumors. Finally, it describes new findings about epigenetic differences-specifically in DNA hypermethylation-among lung tumors, including some male/female differences, which may prove useful as biomarkers for diagnosis, prognosis, and prediction of response to treatments.

The skull of the round Island boa, Casarea dussumieri Schlegel, based on high‐resolution X‐ray computed tomography

The skull of the rare bolyeriid snake Casarea dussumieri is described in detail based on high-resolution X-ray CT data. Bolyeriids are unique in their possession of a separate suborbital ossification and a maxilla subdivided into two movably jointed parts, which may be the result of paedomorphic truncation of the development of the maxilla from multiple ossification centers. Comparison of the skull of C. dussumieri to that of larger booids suggests additional paedomorphic features including reduction of the dorsal lamina of the nasal and prefrontal and reduction of their contacts with the frontal, limited posterior extent of the posterior free process of the supratemporal, and reduction of the coronoid and splenial. The observations herein do not resolve competing phylogenetic hypotheses based on morphology, which either place tropidophiids as the sister-taxon of bolyeriids, Acrochordus and colubroids, or place bolyeriids as the sister-taxon of the other three. But these observations provide no support whatsoever for the heterodox placement of tropidophiids at the base of alethinophidian snakes, as obtained recently with molecular data.

Acute Exacerbation (Acute Lung Injury of Unknown Cause) in UIP and Other Forms of Fibrotic Interstitial Pneumonias

Acute exacerbation of usual interstitial pneumonia (UIP) is a condition in which patients with UIP, and occasionally other forms of fibrotic interstitial lung disease, develop rapid respiratory failure, accompanied by extensive radiologic infiltrates. The pathologic features of this condition are ill-defined in the literature and the outcome is unclear. We report 12 such patients, 9 with underlying UIP, 2 with underlying fibrotic nonspecific interstitial pneumonia, and 1 with underlying chronic hypersensitivity pneumonitis, who underwent surgical lung biopsy for diagnosis. High-resolution computed tomography data were available in 11 cases and showed the presence of extensive bilateral ground-glass opacities, sometimes accompanied by focal consolidation, superimposed on underlying fibrosis. Three microscopic patterns of acute lung injury were seen: diffuse alveolar damage (DAD), organizing pneumonia (OP), and a pattern of numerous very large fibroblast foci superimposed on underlying fibrosis. After the biopsy, all patients were treated with steroids, in some instances accompanied by cyclophosphamide or azathioprine. Ten patients survived the acute episode and were discharged with survival times of 1 to 11 months; of these cases, 6 showed a pattern of OP or OP plus extensive fibroblast foci; 2 a pattern of extensive fibroblast foci only; and 2 a pattern of DAD. Both patients who died had histologic DAD. We conclude that acute exacerbation of UIP and other fibrotic lung diseases produces a variety of pathologic patterns on biopsy, and that patients with OP or extensive fibroblast foci as the acute pattern seem to do better than those with DAD. Our data also imply that survival (of the acute episode) may be better than the literature suggests.

Arrhythmias in Adult Patients With Congenital Heart Disease

By the time patients with congenital heart disease (CHD) reach adolescence and early adulthood, rhythm status has often become an active issue, if not the central issue, in their cardiac management. For some, arrhythmias are intrinsic to the structural malformation itself, as is the case with Wolff-Parkinson-White syndrome in the setting of Ebstein’s anomaly, or atrioventricular (AV) block in the setting of “congenitally corrected” transposition of the great arteries (L-TGA). For most other CHD patients, arrhythmias represent an acquired condition related to the unique myocardial substrate created by surgical scars in conjunction with cyanosis and abnormal pressure/volume loads of long duration. This review will attempt to address the major rhythm difficulties faced by adults with CHD, concentrating on electrophysiological features that distinguish CHD from more conventional forms of adult heart disease. A listing of specific arrhythmias and commonly associated congenital defects is provided in Table 1 to serve as an outline for the discussion. View this table: TABLE 1. Specific Arrhythmias and Associated Defects in Adults With Congenital Heart Disease As of 2001, there were estimated to be 800 000 adults with CHD living in the United States,1 a number that has grown steadily as more survivors of childhood surgery reach maturity. Of these, roughly 45% are considered to have mild forms of CHD (eg, atrial septal defect, valvar pulmonary stenosis), 40% are classified as having moderate disease (eg, tetralogy of Fallot, Ebstein’s anomaly), and 15% are considered to have complex disease (eg, single ventricle, transposition of the great arteries). Although arrhythmias can develop within any of the 3 subgroups, the incidence is highest for patients in the moderate and severe categories. Tetralogy of Fallot is an instructive example of moderate CHD with a large arrhythmia burden. As many as one third of patients with repaired tetralogy develop symptomatic atrial tachycardias by …

VOXEL-MAN TempoSurg A Virtual Reality Temporal Bone Surgery Simulator

Objectives: There is a growing demand for the development of virtual reality surgical simulators. Due to the complex surgical anatomy of the skull base and midface such a simulator has very special requirements concerning accuracy of visualization, cutting process and haptic force feedback. Methods: The anatomical 3D-model of the VOXEL-MAN TempoSurg simulator was derived from high resolution CT-data of actual human temporal bones. Key point of this model is the high resolution of the haptic and the visual rendering. The model can be deformed using different cutting tools. Shutter glasses give the impression of a three-dimensional preparation . A corresponding navigation tool allows controlling the drilling process within the 3 planes. Results: Many of the most demanding challenges of a virtual surgical simulator (position of surgeon, choice of temporal bones, opportunity to work with patient cases, degrees-of-freedom, and working with alternative instruments) have already been accomplished. Conclusions: The VOXEL-MAN TempoSurg simulator allows unlimited, standardized and time-as well as cost-saving training for OR-readiness in temporal bone surgery . The training effect can be augmented using the DICOM CT-files of actual patient cases.

Is HRCT the best way to diagnose idiopathic interstitial fibrosis?

High-resolution computed tomography (HRCT) has been the major advance in the diagnosis of idiopathic interstitial pneumonias in the last two decades. In diffuse lung diseases, HRCT now has a central role in routine diagnostic evaluation, and a major impact on the utility of other diagnostic tests, especially bronchoalveolar lavage and surgical lung biopsy. Numerous published studies have evaluated the accuracy of HRCT. The clinical information was not always utilized to generate a noninvasive diagnosis, however. Despite failure to identify idiopathic pulmonary fibrosis on HRCT in a significant minority of cases, given compatible clinical data, characteristic HRCT appearances justify noninvasive diagnosis in most patients. The limitations of the published studies highlight importance of integrating HRCT data with baseline clinical information and, in selected cases, histopathologic findings. When HRCT and clinical findings are both typical of an individual diffuse lung disease, i.e. 'pathognomonic', it is generally appropriate to institute management based on a confident noninvasive diagnosis. When clinical and HRCT data are divergent, or when HRCT features are 'indeterminate', however, histologic evaluation continues to play an essential role. Integration of histology with radiologic and clinical data is the best way to formulate the final diagnosis in these cases.

CT volumetry of the skeletal tissues

Computed tomography (CT) is an important and widely used modality in the diagnosis and treatment of various cancers. In the field of molecular radiotherapy, the use of spongiosa volume (combined tissues of the bone marrow and bone trabeculae) has been suggested as a means to improve the patient-specificity of bone marrow dose estimates. The noninvasive estimation of an organ volume comes with some degree of error or variation from the true organ volume. The present study explores the ability to obtain estimates of spongiosa volume or its surrogate via manual image segmentation. The variation among different segmentation raters was explored and found not to be statistically significant (p value >0.05). Accuracy was assessed by having several raters manually segment a polyvinyl chloride (PVC) pipe with known volumes. Segmentation of the outer region of the PVC pipe resulted in mean percent errors as great as 15% while segmentation of the pipe's inner region resulted in mean percent errors within approximately 5%. Differences between volumes estimated with the high-resolution CT data set (typical of ex vivo skeletal scans) and the low-resolution CT data set (typical of in vivo skeletal scans) were also explored using both patient CT images and a PVC pipe phantom. While a statistically significant difference (p value <0.002) between the high-resolution and low-resolution data sets was observed with excised femoral heads obtained following total hip arthroplasty, the mean difference between high-resolution and low-resolution data sets was found to be only 1.24 and 2.18 cm3 for spongiosa and cortical bone, respectively. With respect to differences observed with the PVC pipe, the variation between the high-resolution and low-resolution mean percent errors was a high as approximately 20% for the outer region volume estimates and only as high as approximately 6% for the inner region volume estimates. The findings from this study suggest that manual segmentation is a reasonably accurate and reliable means for the in vivo estimation of spongiosa volume. This work also provides a foundation for future studies where spongiosa volumes are estimated by various raters in more comprehensive CT data

Predicting Basal Cochlear Length for Electric-Acoustic Stimulation

To assess the feasibility and accuracy of predicting electrode insertion depth necessary in cochlear implantations for electric-acoustic stimulation by means of preoperative high-resolution computed tomography (HRCT). Human temporal bone study with evaluation of cochlear dimensions. Tertiary care medical center. Eight fresh human temporal bones were scanned, and basal cochlear structures were reconstructed and measured. Standard cochlear implantations with a free-fitting array were performed, and the bones then underwent histologic analysis using a technique that allows sectioning of undecalcified bones. After embedding, all bones underwent conventional radiologic analysis with further insertion measurements. Preimplantation HRCT data were compared with radiologic and histologic data. Preimplantation HRCT-based measurements correlated very well with postimplantation radiologic data. A mean failure of 0.3 mm was found. Mean values for the first 360 degrees ranged from 18.8 to 22.0 mm. Preimplantation HRCT-based prediction of cochlear implant insertion depths is both feasible and accurate. It is especially useful when aiming for hearing preservation, where insertion depths of 360 degrees are necessary.