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Computed Tomography Imaging of Medpor: Graph-Cut Algorithm and Its Accuracy.

J Craniofac Surg. 2012 May 4;

Authors: Liu XJ, Chen L, Song W, Guo CB, Yu GY

Abstract
ABSTRACT: Porous polyethylene has become a popular alloplastic material for maxillofacial reconstruction. Despite its benefits, this material is radiolucent on conventional radiography. Computed tomography of traditional graphic segmentation based on gray levels was reported by a few authors, but the accuracy has not been described. The aim of this study was to image this material using segmentation based on Graph-cut algorithm. Another object was to compare accuracy of 2 algorithms. Between 2005 and 2010, 15 patients (12 females) participated in the study. Computed tomography was used for image acquisition. Graphic segmentation based on gray level involved use of the software OsiriX. Stroke-based specification for user interaction and Graph-cut segmentation involved a self-developed module. The accuracy of both segmentation algorithms was tested by comparing the volume of reconstructed Medpor with the actual volume measured by the draining method during surgery. Twenty-seven comparisons of the computed and actual volumes were gained. Linear regression was done between reconstructed and real volume. For the volume of Graph-cut algorithm, the regression equation was T = -0.19425 + 1.02692S; the difference between the population intercept and zero was not significant (t = -0.83, P = 0.4172). For the volume of gray-level algorithm, the regression equation was T = -1.15282 + 1.14101S; the difference between the population intercept and zero was significant (t = -3.04, P = 0.0055).These results demonstrated porous polyethylene can be well defined by computed tomography segmentation with Graph-cut and gray-level algorithms. Graph-cut algorithm has a better accuracy compared with that of gray-level algorithm.

PMID: 22565895 [PubMed - as supplied by publisher]

The iPad Tablet Computer for Mobile On-Call Radiology Diagnosis? Auditing Discrepancy in CT and MRI Reporting.

J Digit Imaging. 2012 May 5;

Authors: John S, Poh AC, Lim TC, Chan EH, Chong LR

Abstract
Tablet computers such as the iPad, which have a large format, improved graphic display resolution and a touch screen interface, may have an advantage compared to existing mobile devices such as smartphones and laptops for viewing radiological images. We assessed their potential for emergency radiology teleconsultation by reviewing multi-image CT and MRI studies on iPad tablet computers compared to Picture Archival and Communication Systems (PACS) workstations. Annonymised DICOM images of 79 CT and nine MRI studies comprising a range of common on-call conditions, reported on full-featured diagnostic PACS workstation by one Reporting Radiologist, were transferred from PACS to three iPad tablet computers running OsiriX HD v 2.02 DICOM software and viewed independently by three reviewing radiologists. Structured documentation was made of major findings (primary diagnosis or other clinically important findings), minor findings (incidental findings), and user feedback. Two hundred and sixty four readings (88 studies read by three reviewing radiologists) were compared, with 3.4 % (nine of 264) major discrepancies and 5.6 % (15 of 264) minor discrepancies. All reviewing radiologists reported favorable user experience but noted issues with software stability and limitations of image manipulation tools. Our results suggest that emergency conditions commonly encountered on CT and MRI can be diagnosed using tablet computers with good agreement with dedicated PACS workstations. Shortcomings in software and application design should be addressed if the potential of tablet computers for mobile teleradiology is to be fully realized.

PMID: 22562174 [PubMed - as supplied by publisher]

Comparison of femoral tunnel length between transportal and retrograde reaming outside-in techniques in anterior cruciate ligament reconstruction.

Knee Surg Sports Traumatol Arthrosc. 2012 May 3;

Authors: Kim JG, Wang JH, Ahn JH, Kim HJ, Lim HC

Abstract
PURPOSE: To evaluate the accuracy of intraoperative femoral tunnel length measurement and to compare this between the transportal (TP) and outside-in (OI) techniques for double-bundle (DB) anterior cruciate ligament (ACL) reconstruction. METHODS: Eighty patients underwent a DB ACL reconstruction using either the TP or the OI technique. The participants were randomized to either a TP group (I, 40 cases) or a OI group (II, 40 cases). The intraoperatively measured femoral tunnel length was recorded, and the postoperative femoral tunnel length was measured using computed tomography with OsiriX(®) imaging software. RESULTS: The mean femoral tunnel lengths measured intraoperatively in Group II (38.9 ± 3.0 mm for anteromedial [AM], 39.3 ± 3.4 mm for posterolateral [PL]) were significantly longer than those of Group I (34.8 ± 2.7 mm for AM, 36.0 ± 3.2 mm for PL) (P < 0.001). The mean AM femoral tunnel length measured postoperatively in Group II (33.3 ± 3.8 mm) was significantly longer than that in Group I (31.1 ± 2.9 mm) (P = 0.006). The mean intraoperatively measured femoral tunnel length was significantly longer than that measured postoperatively in Groups I and II (P < 0.001). CONCLUSION: After anatomic DB ACL reconstruction, the femoral tunnel length of the OI technique measured intraoperatively (AM/PL) and postoperatively (AM) was longer than those of the TP technique. The femoral tunnel length measured intraoperatively was longer than that measured postoperatively in both TP and OI technique. This study may help surgeons to measure femoral tunnel length accurately in anatomic DB ACL reconstruction with suspensory fixation device. LEVEL OF EVIDENCE: Prospective randomized controlled trial, Level I.

PMID: 22552615 [PubMed - as supplied by publisher]

Console-Integrated Stereoscopic OsiriX 3D Volume-Rendered Images for da Vinci Colorectal Robotic Surgery.

Surg Innov. 2012 May 1;

Authors: Volonté F, Pugin F, Buchs NC, Spaltenstein J, Hagen M, Ratib O, Morel P

Abstract
The increased distance between surgeon and surgical field is a significant problem in laparoscopic surgery. Robotic surgery, although providing advantages for the operator, increases this gap by completely removing force feedback. Enhancement with visual tools can therefore be beneficial. The goal of this preliminary work was to create a custom plugin for OsiriX to display volume-rendered images in the da Vinci surgeon's console. The TilePro multi-input display made the generated stereoscopic pairs appear to have depth. Tumor position, vascular supply, spatial location, and relationship between organs appear directly within the surgeon's field of view. This study presents a case of totally robotic right colectomy for cancer using this new technology. Sight diversion was no longer necessary. Depth perception was subjectively perceived as profitable. Total immersion in the operative field helped compensate for the lack of tactile feedback specific to robotic intervention. This innovative tool is a step forward toward augmented-reality robot-assisted surgery.

PMID: 22549904 [PubMed - as supplied by publisher]

Anatomical parameters of subaxial percutaneous transfacet screw fixation based on the analysis of 50 computed tomography scans.

J Neurosurg Spine. 2012 Apr 20;

Authors: Milchteim C, Yu WD, Ho A, O'Brien JR

Abstract
Object Cervical transfacet screw placement has been described in the literature. Although the technique shows promise for percutaneous application, parameters for screw placement have not been well delineated. This study used reconstructed CT scans with imaging software to assess the feasibility of percutaneous transfacet screw placement, analyzing potential entry angles, transfacet lengths, and sex differences at each subaxial level. Methods Fifty consecutive cervical CT scans (obtained in 26 males and 24 females [mean age 41.5 years]) were reformatted using OsiriX software, and transfacet lengths, entry angles, and potential occipital clearance were analyzed at all subaxial levels. Statistical analyses were used to determine the differences, if any, between transfacet lengths, entry angle, and occipital clearance across individual cervical levels. Repeatability was quantified by calculating the intraclass correlation coefficient and Cohen kappa value. Results A total of 200 transfacet lengths and 200 entry angles in 50 patients were analyzed. The mean transfacet lengths were 17.9 ± 2.6, 17.6 ± 3.2, 16.3 ± 3.6, and 13.1 ± 2.2 mm at C3-4, C4-5, C5-6, and C6-7, respectively, with mean entry angles at 52.7° ± 7.8°, 56.5° ± 8.0°, 55.0° ± 8.8°, and 53.0° ± 8.7°, respectively. Analysis of variance revealed a significant difference between the mean transfacet lengths, while post hoc analysis revealed significantly larger transfacet lengths in the upper 2 cervical levels (C3-4 and C4-5) than in the lower 2 cervical levels (C5-6 and C6-7). Analysis of variance demonstrated no significant difference between the entry angles. Males had significantly larger transfacet lengths at C5-6 (17.4 vs 15.1 mm) and C6-7 (13.7 vs 12.4 mm) than females. The occiput would have blocked percutaneous screw placement in 86%, 78%, 54%, and 20% of the cases at C3-4, C4-5, C5-6, and C6-7, respectively. Transfacet lengths may accommodate longer screws in the upper cervical spine, but potential screw sizes decrease in the lower subaxial levels. A transfacet entry angle of approximately 50° or greater was associated with a higher incidence of occipital clearance. Additionally, the occiput may pose a significant obstruction to percutaneous transfacet fixation in upper subaxial levels. Interrater reliability was poor for screw angle and length measurements, but was satisfactory in intrarater analysis in 6 of 8 measurements. There was moderate to good agreement of occipital clearance in all but one measurement. Conclusions Cervical transfacet screw placement is possible from C-3 to C-7. Because occipital clearance can be difficult at C3-4 and C6-7, the use of curved or flexible instruments may be necessary to obtain the appropriate screw trajectory. Screw lengths varied with spinal level and the sex of the patient.

PMID: 22519926 [PubMed - as supplied by publisher]

Effects of Abdominal Fat Distribution Parameters on Severity of Acute Pancreatitis.

World J Surg. 2012 Apr 11;

Authors: O'Leary DP, O'Neill D, McLaughlin P, O'Neill S, Myers E, Maher MM, Redmond HP

Abstract
BACKGROUND: Obesity is a well-established risk factor for acute pancreatitis. Increased visceral fat has been shown to exacerbate the pro-inflammatory milieu experienced by patients. This study aimed to investigate the relationship between the severity of acute pancreatitis and abdominal fat distribution parameters measured on computed tomography (CT) scan. METHODS: Consecutive patients admitted to Cork University Hospital with acute pancreatitis between January 2005 and December 2010 were evaluated for inclusion in the study. An open source image analysis software (Osirix, v 3.9) was used to calculate individual abdominal fat distribution parameters from CT scans by segmentation of abdominal tissues. RESULTS: A total of 214 patients were admitted with pancreatitis between January 2005 and December 2010. Sixty-two of these patients underwent a CT scan and were thus eligible for inclusion. Visceral fat volume was the volumetric fat parameter that had the most significant association with severe acute pancreatitis (P = 0.003). There was a significant association between visceral fat volume and subsequent development of systemic complications of severe acute pancreatitis (P = 0.003). There was a strong association between mortality and visceral fat volume (P = 0.019). Multivariate regression analysis, adjusted for gender, did not identify any individual abdominal fat distribution index as an independent risk factor for severe acute pancreatitis. CONCLUSIONS: Overall, estimation of abdominal fat distribution parameters from CT scans performed on patients with acute pancreatitis indicates a strong association between visceral fat, severe acute pancreatitis, and the subsequent development of systemic complications. These data suggest that visceral fat volume should be incorporated into future predictive scoring systems.

PMID: 22491816 [PubMed - as supplied by publisher]

The new era of radiology teaching files.

AJR Am J Roentgenol. 2012 Apr;198(4):773-6

Authors: Rojas CA, Jawad H, Chung JH

Abstract
OBJECTIVE: In this article, we describe how we constructed a radiology teaching file that simulates real-life scenarios and discuss some of the advantages it affords. CONCLUSION: Using OsiriX imaging software and iWork Pages, we have created a HIPAA-compliant interstitial lung disease radiology teaching resource that allows the user to navigate through the complete dataset of images for each patient. Integrated within the file is a navigation tool that allows the user to access the patient's clinical report, imaging reports, pulmonary function tests, and pathology report simultaneously. To our knowledge, this is the first teaching file of its kind.

PMID: 22451540 [PubMed - in process]

Is Femoral Tunnel Length Correlated With the Intercondylar Notch and Femoral Condyle Geometry After Double-Bundle Anterior Cruciate Ligament Reconstruction Using the Transportal Technique? An In Vivo Computed Tomography Analysis.

Arthroscopy. 2012 Mar 13;

Authors: Wang JH, Kim JG, Ahn JH, Lim HC, Hoshino Y, Fu FH

Abstract
PURPOSE: To analyze femoral tunnel geometry using computed tomography (CT) imaging and evaluate the anatomic factors affecting femoral tunnel length after anterior cruciate ligament (ACL) reconstruction by the transportal technique. METHODS: Twenty-nine patients underwent an anatomic double-bundle ACL reconstruction with a femoral tunnel drill by the transportal technique. CT imaging with OsiriX software (version 3.8; Pixmeo, Geneva, Switzerland) was used to measure femoral tunnel length (anteromedial [AM], posterolateral [PL], and central), femoral tunnel divergent angle, and femoral condyle size and intercondylar notch size parameters. Correlations between femoral tunnel length and femoral condyle size and intercondylar notch size parameters were analyzed. RESULTS: The mean AM, PL, and central femoral tunnel lengths were 33.3 ± 3.9 mm, 33.6 ± 3.6 mm, and 34.3 ± 3.2 mm, respectively. A femoral tunnel length of less than 30 mm developed in 7 cases (24.1%) in the AM aspect and 4 cases (13.8%) in the PL aspect. The mean femoral tunnel divergent angle was 14.4° ± 4.1°. A positive correlation was found between AM, not PL or central, femoral tunnel length and medial femoral condyle anteroposterior (AP) distance (P = .01, r = 0.46), lateral femoral condyle AP distance (P = .01, r = 0.43), medial-to-lateral epicondylar distance (P = .03, r = 0.39), middle notch width (P = .009, r = 0.47), notch height (P = .001, r = 0.57), and notch area (P < .001, r = 0.58). CONCLUSIONS: After double-bundle ACL reconstruction with the transportal technique through the accessory anteromedial portal, the AM and PL femoral tunnels showed mean tunnel length greater than 30 mm and a divergent angle. However, a femoral tunnel length of less than 30 mm developed in some cases. AM femoral tunnel length was correlated with femoral condyle size (medial femoral condyle AP distance, lateral femoral condyle AP distance, and medial-to-lateral epicondylar distance) and intercondylar notch size (notch width, notch height, and notch area). LEVEL OF EVIDENCE: Level IV, therapeutic case series.

PMID: 22421566 [PubMed - as supplied by publisher]

Quantitative Paraspinal Muscle Measurements: Inter-Software Reliability and Agreement Using OsiriX and ImageJ.

Phys Ther. 2012 Mar 8;

Authors: Fortin M, Battié MC

Abstract
BackgroundVariations in paraspinal muscle cross-sectional area (CSA) and composition, particularly of multifidus, have been of interest with respect to risk of, and recovery from, low back pain problems. Several studies have reported on the reliability of such muscle measurements using various protocols and image analysis programs. However, there is neither a standard protocol for tissue segmentation nor an investigation reporting on reliability or agreement of measurements using different software.ObjectiveTo provide a detailed muscle measurement protocol and determine the reliability and agreement of associated paraspinal muscle composition measurements obtained with two commonly used image analysis programs, OsiriX and ImageJ.DesignA measurement reliability study. METHODS:/b>Lumbar magnetic resonance images (MRI) of 30 subjects were randomly selected from a cohort of patients with various low back conditions. Muscle CSA and composition measurements were acquired from axial T2-weighted magnetic resonance images of the multifidus, erector spinae, and the two muscles combined at L4-L5 and S1 for each subject. All measurements were repeated twice using each software program, at least 5 days apart. The assessor was blinded to all earlier measurements. RESULTS: /b>The intra-rater reliability and standard error of measurement (SEM) were comparable for most measurements obtained using OsiriX or ImageJ, with reliability coefficients (ICCs) measurements varying between 0.77-0.99 for OsiriX and 0.78-0.99 for ImageJ. There was similarly excellent agreement between muscle composition measurements using the two software applications (inter-software ICCs=0.81-0.99).LimitationsThe high degree of inter-software measurement reliability may not generalize to protocols using other commercial or custom software. CONCLUSION:/b>The proposed method to investigate paraspinal muscle CSA, composition and side-to-side asymmetry was highly reliable, with excellent agreement between the two employed software programs.

PMID: 22403091 [PubMed - as supplied by publisher]

The application of traditional and geometric morphometric analyses for forensic quantification of sexual dimorphism: preliminary investigations in a Western Australian population.

Int J Legal Med. 2012 Mar 8;

Authors: Franklin D, Cardini A, Flavel A, Kuliukas A

Abstract
A current limitation of forensic practice in Western Australia is a lack of contemporary population-specific standards for biological profiling; this directly relates to the unavailability of documented human skeletal collections. With rapidly advancing technology, however, it is now possible to acquire accurate skeletal measurements from 3D scans contained in medical databases. The purpose of the present study, therefore, is to explore the accuracy of using cranial form to predict sex in adult Australians. Both traditional and geometric morphometric methods are applied to data derived from 3D landmarks acquired in CT-reconstructed crania. The sample comprises multi-detector computed tomography scans of 200 adult individuals; following 3D volume rendering, 46 anatomical landmarks are acquired using OsiriX (version 3.9). Centroid size and shape (first 20 PCs of the Procrustes coordinates) and the inter-landmark (ILD) distances between all possible pairs of landmarks are then calculated. Sex classification effectiveness of the 3D multivariate descriptors of size and shape and selected ILD measurements are assessed and compared; robustness of findings is explored using resampling statistics. Cranial shape and size and the ILD measurements are sexually dimorphic and explain 3.2 to 54.3 % of sample variance; sex classification accuracy is 83.5-88.0 %. Sex estimation using 3D shape appears to have some advantages compared to approaches using size measurements. We have, however, identified a simple and biologically meaningful single non-traditional linear measurement (glabella-zygion) that classifies Western Australian individuals according to sex with a high degree of expected accuracy (87.5-88 %).

PMID: 22399102 [PubMed - as supplied by publisher]

Stability of voxel values from cone-beam computed tomography for dental use in evaluating bone mineral content.

Clin Oral Implants Res. 2012 Feb 10;

Authors: Nomura Y, Watanabe H, Shirotsu K, Honda E, Sumi Y, Kurabayshi T

Abstract
OBJECTIVES: The objective of this study was to investigate the stability of voxel values from cone-beam CT (CBCT) using a flat panel detector in changing surrounding circumstances mimicking clinical situations. MATERIALS AND METHODS: Seven hydroxyapatite (HA) rods (0, 40, 80, 120, 160, 199, and 239 mg Ca/cm(3) ) were set in a 16 cm diameter water phantom and scanned with CBCT (FineCube) and also with multislice CT (MSCT) used as reference. The voxel values from CBCT were measured by the obtained images with OsiriX software (http://www.osirix-viewer.com), and compared with the CT numbers from MSCT. We examined the correlation between the voxel values and the HA contents, the variance of voxel values, and the influence of changing surrounding circumstances on the voxel values. RESULTS: The voxel values from CBCT were different from the CT numbers from MSCT, but there was a linear Pearson correlation between the voxel values and the HA contents. The voxel values were greatly influenced when the samples were scanned surrounded in air. However, the voxel values were not affected significantly in the existence of materials simulating oral hard tissues and/or a metal core post. CONCLUSIONS: There was a linear correlation between the voxel values of CBCT and the contents of HA rod samples. Our study indicated that it might be possible to evaluate bone mineral content(BMC) from the voxel values of CBCT for dental implant treatment.

PMID: 22320314 [PubMed - as supplied by publisher]

Subendocardial contractile impairment in chronic ischemic myocardium: assessment by strain analysis of 3T tagged CMR.

J Cardiovasc Magn Reson. 2012 Feb 2;14(1):14

Authors: Nagao M, Hatakenaka M, Matsuo Y, Kamitani T, Higuchi K, Shikata F, Nagashima M, Mochizuki T, Honda H

Abstract
ABSTRACT: BACKGROUND: The purpose of this study was to quantify myocardial strain on the subendocardial and epicardial layers of the left ventricle (LV) using tagged MRI and to investigate the transmural degree of contractile impairment in the chronic ischemic myocardium. METHODS: 3T tagged MR imaging was performed at rest in 12 patients with severe coronary artery disease who had been scheduled for coronary artery bypass grafting. Circumferential strain (C-strain) at end-systole on subendocardial and epicardial layers was measured using the short-axis tagged images of the LV and available software (Intag; Osirix). The myocardial segment was divided into stenotic and non-stenotic segments by invasive coronary angiography, and ischemic and non-ischemic segments by stress myocardial perfusion scintigraphy. The difference in C-strain between the two groups was analyzed using the Mann-Whitney U-test. The diagnostic capability of C-strain was analyzed using receiver operating characteristics analysis. RESULTS: The absolute subendocardial C-strain was significantly lower for stenotic (-7.5+/-12.6 %) than non-stenotic segment (-18.8+/-10.2 %, p <0.0001). There was no difference in epicardial C-strain between the two groups. Use of cutoff thresholds for subendocardial C-strain differentiated stenotic segments from non-stenotic segments with a sensitivity of 77%, a specificity of 70%, and areas under the curve (AUC) of 0.76. The absolute subendocardial C-strain was significantly lower for ischemic (-6.7+/-13.1%) than non-ischemic segments (-21.6+/-7.0%, p<0.0001). The absolute epicardial C-strain was also significantly lower for ischemic (-5.1+/-7.8%) than non-ischemic segments (-9.6+/-9.1%, p<0.05). Use of cutoff thresholds for subendocardial C-strain differentiated ischemic segments from non-ischemic segments with sensitivities of 86%, specificities of 84%, and AUC of 0.86. CONCLUSIONS: Analysis of tagged MRI can non-invasively demonstrate predominate impairment of subendocardial strain in the chronic ischemic myocardium at rest.

PMID: 22300290 [PubMed - as supplied by publisher]

Volume changes in aortic true and false lumen after the "PETTICOAT" procedure for type B aortic dissection.

J Vasc Surg. 2012 Jan 27;

Authors: Melissano G, Bertoglio L, Rinaldi E, Civilini E, Tshomba Y, Kahlberg A, Agricola E, Chiesa R

Abstract
BACKGROUND: The PETTICOAT (Provisional ExTension to Induce COmplete ATtachment) technique may be employed during endovascular treatment of type B aortic dissection (TBD) using self-expandable bare stents distal to the covered stent graft placed over the proximal entry tear. The aim of this study is to evaluate the volume changes of the true (TL) and false lumen (FL) on computed tomography (CT) scans. METHODS: Since 2005, 25 selected patients received endovascular treatment for complicated TBD with the PETTICOAT technique employing the Zenith Dissection Endovascular System (William Cook Europe, Bjaerverskov, Denmark). Indications to the use of the PETTICOAT technique were the evidence of clinical manifest dynamic malperfusion in five cases (20%) and/or radiologic evidence of TL collapse in 20 cases (80%). Five patients were treated within 2 weeks from onset, 13 patients between 2 weeks and 3 months, and seven patients over 3 months after the initial acute event. The volumetric analysis of the changes of TL and FL obtained from CT scan performed before endovascular treatment of TBD, postoperatively and yearly thereafter were analyzed using the OsiriX software v 3.9 (Pixmeo sarl, Bernex, Switzerland). RESULTS: Initial clinical (30 days) and midterm clinical success was observed in 21 cases (84%) and in 23 cases (92%), respectively. The volumes of the aortic TL and FL were evaluated at 30 days and midterm follow-up (mean, 38 ± 17 months). The following TL volumes were recorded: baseline 84 ± 29 cm(3), postoperative 167 ± 31 cm(3)(+98%), 1 year 193 ± 46 cm(3)(+131%), and 2 years 216 ± 54 cm(3)(+140%). The following FL volumes were recorded: baseline 332 ± 86 cm(3), postoperative 286 ± 85 cm(3)(-14%), 1 year 233 ± 81 cm(3)(-30%), and 2 years 248 ± 112 cm(3)(-32%). Progressive remodeling of the TL was recorded over time in both thoracic and abdominal segments with shrinkage of the FL mainly in the thoracic segment. CONCLUSIONS: These data provide insight into potential therapeutic benefit of the PETTICOAT technique. A significant immediate increase in TL could be achieved with resolution of all cases of dynamic malperfusion and TL collapse. A different behavior of volumes in the thoracic and abdominal segments was observed.

PMID: 22285874 [PubMed - as supplied by publisher]