scholarly journals A New Automated Way to Measure Polyethylene Wear in THA Using a High Resolution CT Scanner: Method and Analysis

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Gerald Q. Maguire Jr. ◽  
Marilyn E. Noz ◽  
Henrik Olivecrona ◽  
Michael P. Zeleznik ◽  
Lars Weidenhielm
Keyword(s):  
Computed Tomography ◽  
Femoral Component ◽  
Polyethylene Wear ◽  
Human Interaction ◽  
Ct Scanner ◽  
Acetabular Cup ◽  
Computed Tomography Imaging ◽  
The Mean ◽  
Active Patients ◽  
Ct Volume

As the most advantageous total hip arthroplasty (THA) operation is the first, timely replacement of only the liner is socially and economically important because the utilization of THA is increasing as younger and more active patients are receiving implants and they are living longer. Automatic algorithms were developed to infer liner wear by estimating the separation between the acetabular cup and femoral component head given a computed tomography (CT) volume. Two series of CT volumes of a hip phantom were acquired with the femoral component head placed at 14 different positions relative to the acetabular cup. The mean and standard deviation (SD) of the diameter of the acetabular cup and femoral component head, in addition to the range of error in the expected wear values and the repeatability of all the measurements, were calculated. The algorithms resulted in a mean (±SD) for the diameter of the acetabular cup of 54.21 (±0.011) mm and for the femoral component head of 22.09 (±0.02) mm. The wear error was ±0.1 mm and the repeatability was 0.077 mm. This approach is applicable clinically as it utilizes readily available computed tomography imaging systems and requires only five minutes of human interaction.

scholarly journals Comparison of the Hounsfield Unit Values Obtained From Cone-Beam Computed Tomography (CBCT) and Multidetector Computed Tomography (MDCT) Images for Different Bone Densities

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Atefeh Khavid ◽  
Mojgan Sametzadeh ◽  
Mostafa Godiny ◽  
Mohammad Mehdi Moarrefpour
Keyword(s):  
Computed Tomography ◽  
Cone Beam Computed Tomography ◽  
Pearson Correlation ◽  
Hounsfield Unit ◽  
Cone Beam ◽  
Ct Scanner ◽  
Significance Level ◽  
Dental Practitioners ◽  
Significant Difference ◽  
The Mean

Background and objective: In recent years, cone-beam computed tomography (CBCT) has become a key diagnostic tool in dentistry. CBCT can provide 3D images of the maxillofacial area to help dental practitioners in diagnosis and treatment, especially implant placement and treatment of pathogenic lesions. This study aimed to compare the Hounsfield Unit (HU) values obtained from CBCT images for bones of different densities with the corresponding HU values from MDCT images. Materials and methods: cube-shaped bone blocks of identical size were cut from the middle section of the cow ribs and femur area such that they had a layer of cortical bone in their buccal, lingual, and top surfaces and trabecular bone in the middle. MDCT scans were performed using a Somatom Sensation Ct Scanner. After determining HU from the results of these scans, nine suitable specimens from different ranges of HU were chosen for comparison. HU of the CBCT images was computed by the dedicated software of the CBCT machine. Finally, HU values obtained from MDCT and CBCT were compared. Data analysis was performed using SPSS version 25 at the 0.05 significance level. Results: The results showed a statistically significant difference between the mean HU from MDCT images and the mean HU from CBCT images (P<0.05). For similar specimens, CBCT produced higher mean HU values than MDCT. The Pearson correlation test detected a significant direct relationship between the HU values of specimens in MDCT and CBCT (P<0.05). Conclusion: For the tools and software used in this study, there was no significant difference between the HU values obtained from MDCT and CBCT, but the mean HU obtained from CBCT was higher than that from MDCT.

scholarly journals Incidental Findings Diagnosed during Preprocedural Evaluation of TAVR

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Levent Sahiner ◽  
Cem Coteli ◽  
Ahmet Kivrak ◽  
Yusuf Ziya Sener ◽  
Serkan Asil ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Therapeutic Option ◽  
Computed Tomography Imaging ◽  
Transcatheter Aortic Valve ◽  
High Surgical Risk ◽  
Complex Procedure ◽  
Cardiology Clinic ◽  
Extensive Information ◽  
The Mean ◽  
Adult Hospital

Introduction. Transcatheter aortic valve replacement is an important therapeutic option for aortic stenosis (AS) patients who have high surgical risk. TAVR is a complex procedure. Proper preparation of the patient is of significant importance for the final success and affects the morbidity and mortality of the TAVR directly. Pre-TAVR computed tomography is one of the corner stones of these preparation steps, and many patients get some incidental diagnoses. Materials and Methods. In this trial, we have investigated 155 patients who had underwent TAVR between February 2013 and March 2017 at Hacettepe University Adult Hospital Cardiology Clinic. Results. Total number of incidental diagnoses was 541, and 451 of them were the first diagnoses. Total number of cardiovascular findings and noncardiovascular findings was 369 and 172, respectively. The most common cardiovascular finding is atherosclerotic heart disease (139, 89.6%). The most common noncardiovascular finding is pulmonary nodule (41, 26.4%). 143 of 155 patients had at least one incidental diagnosis after the reassessment, and 33 different diagnoses were identified with computed tomography. The mean STS-PROM was 8.38% (range 2.8% to 23%), and the mean STS-PROM was calculated 9.4% (range 3.6% to 23%) after the reassessment of computed tomography. Conclusion. Preprocedural evaluation is one of the most important steps in TAVR. Computed tomography imaging provides extensive information, not only for procedure planning. Our findings emphasize that computed tomography has a crucial role for the preprocedural evaluation of TAVR candidates.

Eye Lens Dose in Cranial Computed Tomography with Reference to the Technical Development of CT Scanners

1986 ◽  
Vol 27 (5) ◽  
pp. 599-606 ◽  
Author(s):  
U. Moström ◽  
C. Ytterbergh ◽  
K. Bergström
Keyword(s):  
Computed Tomography ◽  
Spatial Distribution ◽  
Technical Development ◽  
Cranial Computed Tomography ◽  
Eye Lens ◽  
Ct Scanner ◽  
Cranial Ct ◽  
Eye Lens Dose ◽  
Patient Groups ◽  
The Mean

The continuous technical development of cranial CT and the accumulation of clinical experience with this method, have resulted in the use of an increasing number of scan protocols for different clinical situations. An investigation was undertaken to find out how this change has influenced the dose delivered to the patient. The eye lens dose was measured at CT examinations in 245 patients, with appropriate scan protocols, and also at corresponding examinations in an anthropomorphic head phantom. One CT scanner of early (EMI CT 1010) and one of modern design (Siemens Somatom DR2) were investigated. The range of the eye lens dose was wide, namely 4 to 206 mGy for EMI CT 1010 and 6 to 124 mGy for Somatom DR2. In patient groups with comparable scan protocols the mean eye lens dose was higher with the Somatom DR2, mostly on account of a different spatial distribution of the dose in the scan plane. The dose varied less with this scanner, however, mainly because of the possibilities for more accurate positioning.

scholarly journals Computed tomography is not necessary to assess rotation of the femoral component in navigation-assisted total knee replacement

2016 ◽  
Vol 44 (6) ◽  
pp. 1314-1322 ◽  
Author(s):  
Daniel Hernández-Vaquero ◽  
Alfonso Noriega-Fernandez ◽  
Ivan Perez-Coto ◽  
Manuel A. Sandoval García ◽  
Andres A. Sierra-Pereira ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Total Knee Replacement ◽  
Femoral Component ◽  
Knee Replacement ◽  
Transepicondylar Axis ◽  
Component Rotation ◽  
Preoperative Ct ◽  
Total Knee ◽  
The Mean ◽  
Ct Data

Objective To demonstrate that postoperative computed tomography (CT) is not needed if navigation is used to determine the rotational position of the femoral component during total knee replacement (TKR). Methods Preoperative CT, navigational, and postoperative CT data of 70 TKR procedures were analysed. The correlation between the rotational angulation of the femur measured by CT and that measured by perioperative navigation was examined. The correlation between the femoral component rotation determined by navigation and that determined by CT was also assessed. Results The mean femoral rotation determined by navigation was 2.64° ± 4.34°, while that shown by CT was 6.43° ± 1.65°. Postoperative rotation of the femoral component shown by CT was 3.09° ± 2.71°, which was closely correlated with the angle obtained through the intraoperative transepicondylar axis by navigation (Pearson’s R = 0.930). Conclusions Navigation can be used to collect the preoperative, intraoperative, and postoperative data and final position of the TKR. The rotation of the femoral component can be determined using navigation without the need for CT.

Hip resurfacing with a highly cross-linked polyethylene acetabular liner and a titanium nitride-coated femoral component

2018 ◽  
Vol 28 (4) ◽  
pp. 422-428 ◽  
Author(s):  
James W Pritchett
Keyword(s):  
Titanium Nitride ◽  
Femoral Component ◽  
Acetabular Component ◽  
Polyethylene Wear ◽  
Hip Resurfacing ◽  
Harris Hip Score ◽  
Kaplan Meier ◽  
Joint Biomechanics ◽  
Cementless Femoral Component ◽  
The Mean

Aims: This study evaluated a specific hip resurfacing system to determine the: (1) function and complications, (2) implant survivorship, (3) acetabular bone conservation and joint biomechanics and (4) osteolysis and polyethylene wear. Methods: I performed 234 resurfacing procedures (192 patients) using a two-piece titanium acetabular component with a 4 mm highly cross-linked polyethylene liner and a cementless titanium nitride-coated titanium femoral component. Function was assessed with Harris Hip, WOMAC, SF-12, and UCLA scores. Radiography and CT scans were used to evaluate bone retention, component position, joint biomechanics, and osteolysis. Retrieved polyethylene liners were analyzed for wear. Results: Median follow-up was 8 years and patients averaged 48 years of age at surgery. The mean Harris Hip Score was 96 and all scores improved significantly. Kaplan-Meier survivorship was 97%. The mean medial acetabular thickness was 9 mm postoperatively versus 14 mm preoperatively ( p = 0.019). Femoral bone conservation (head:neck ratio) was 1.36 postoperatively versus 1.42 preoperatively ( p = 0.02). There was no polyethylene wear through or osteolysis. Eight polyethylene retrievals had a mean wear of 0.05 mm/yr. Conclusions: Resurfacing with a highly cross-linked polyethylene acetabular component and a titanium nitride-coated titanium cementless femoral component is a reliable and bone-conserving procedure at mid-term.

scholarly journals Positional Differences of the Mandibular Canal in Relation to Permanent Mandibular First Molars with Eruption Disturbances in Children

Children ◽  
2020 ◽  
Vol 7 (11) ◽  
pp. 206
Author(s):  
Eungyung Lee ◽  
Taesung Jeong ◽  
Jonghyun Shin
Keyword(s):  
Computed Tomography ◽  
Retrospective Study ◽  
Mandibular Canal ◽  
Normal Group ◽  
Cone Beam ◽  
Computed Tomography Imaging ◽  
Cross Sectional ◽  
Tomography Imaging ◽  
Inferior Margin ◽  
The Mean

Eruption disturbances in permanent mandibular first molars (PM1s) are uncommon. This retrospective study aimed to investigate differences in the position of the mandibular canal in relation to PM1s, with or without, eruption disturbances. Panoramic and cross-sectional views were reconstructed from cone-beam computed tomography imaging of children with PM1 eruption disturbances. Distances from the most inferior margin of the mandible to the center of the mandibular canal (M–C) and from the outer margin of the lingual cortex to the center of the mandibular canal (L–C) were measured for normally erupted PM1s (normal group) and for PM1s with eruption disturbances (ED group) and compared using independent t-tests. The mean M–C was significantly shorter in the ED group (4.86 ± 1.07 mm) than in the normal group (6.56 ± 1.06 mm) (p < 0.05). The mean L–C was also significantly shorter in the ED group (2.74 ± 0.74 mm) than in the normal group (3.09 ± 0.71 mm) (p < 0.05). This study demonstrated that the mandibular canal tended to be positioned more inferiorly in relation to PM1s with eruption disturbances than normally erupted PM1s in children. Clinicians should be aware of this positional deviation when managing children with PM1 eruption disturbances.

Intraoperative Computed Tomography for Registration of Stereotactic Frame in Frame-Based Deep Brain Stimulation

2020 ◽  
Author(s):  
Michael R Jones ◽  
Archit B Baskaran ◽  
Mark J Nolt ◽  
Joshua M Rosenow
Keyword(s):  
Computed Tomography ◽  
Deep Brain Stimulation ◽  
Electrode Placement ◽  
Absolute Difference ◽  
Ct Scanner ◽  
Intraoperative Ct ◽  
Stereotactic Frame ◽  
The Mean ◽  
Conventional Ct ◽  
Deep Brain

Abstract BACKGROUND Deep brain stimulation (DBS) electrode placement utilizing a frame-based technique requires registration of the stereotactic frame with computed tomography (CT) or magnetic resonance (MR) imaging. This traditionally has been accomplished with a conventional CT scanner. In recent years, intraoperative CT has become more prevalent. OBJECTIVE To compare the coordinates obtained with intraoperative CT and conventional CT for registration of the stereotactic frame for DBS. METHODS Patients undergoing DBS electrode placement between 2015 and 2017, who underwent both conventional and intraoperative CT for registration of the stereotactic frame, were included for analysis. The coordinates for the stereotactic target, anterior commissure, and posterior commissure for each CT method were recorded. The mean, maximum, minimum, and standard deviation of the absolute difference for each of the paired coordinates was calculated. Paired t-tests were performed to test for statistical significance of the difference. The directional difference as well as the vector error between the paired coordinates was also calculated. RESULTS The mean absolute difference between conventional and intraoperative CT for the coordinate pairs was less than 0.279 mm or 0.211 degrees for all coordinate pairs analyzed. This was not statistically significant for any of the coordinate pairs. Moreover, the maximum absolute difference between all coordinate pairs was 1.04 mm. CONCLUSION Intraoperative CT imaging provides stereotactic frame registration coordinates that are similar to those obtained by a standard CT scanner. This may save time and hospital resources by obviating the need for the patient to go to the radiology department for a CT scan.

scholarly journals Using a Somatosensory Controller to Assess Body Size for Size-Specific Dose Estimates in Computed Tomography

2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
Jay Wu ◽  
Ruo-Ping Han ◽  
Yan-Lin Liu
Keyword(s):  
Computed Tomography ◽  
Body Size ◽  
Low Cost ◽  
Microsoft Kinect ◽  
Depth Image ◽  
Effective Diameter ◽  
Dose Estimation ◽  
Ct Scanner ◽  
The Mean ◽  
Anterior Posterior

Computed tomography (CT) has been widely used in the healthcare environment. Presently, the radiation dose in CT is determined using the size-specific dose estimate (SSDE). Accurate assessment of individual’s body size is essential for dose estimation. In this study, we integrated a somatosensory controller with a CT scanner to measure patient’s anterior-posterior diameter (APD) and lateral diameter (LATD) and calculate the corresponding effective diameter (ED). A total of 108 individuals with an average age of 38.6 years were enrolled in this study. Microsoft Kinect was used to acquire the depth image of subjects. A grayscale-to-surface height conversion curve was created using acrylic sheets for APD estimation. The APD, LATD, and ED were measured and compared with the results obtained using F ruler and CT images. The mean absolute differences for APD, LATD, and ED between Kinect and F ruler measurements were 5.2%, 1.3%, and 2.5%, respectively, while those between Kinect and CT measurements were 8.8%, 2.6%, and 5.0%, respectively. Kinect can replace CT or F ruler for real-time body size measurements. The use of the somatosensory controller has the advantages of simple, low cost, no radiation, and automatic calculation. It can accurately estimate patient’s APD, LATD, and ED for SSDE.

scholarly journals An accelerometer-based navigation system provides acetabular cup orientation accuracy comparable to that of computed tomography-based navigation during total hip arthroplasty in the supine position

2019 ◽  
Author(s):  
Tomonori Tetsunaga ◽  
Kazuki Yamada ◽  
Tomoko Tetsunaga ◽  
Tomoaki Sanki ◽  
Yoshi Kawamura ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Total Hip Arthroplasty ◽  
Hip Arthroplasty ◽  
Supine Position ◽  
Polyethylene Wear ◽  
Anterolateral Approach ◽  
Navigation Systems ◽  
Acetabular Cup ◽  
Total Hip ◽  
Significant Difference

Abstract Background: Inadequate acetabular component orientation is associated with postoperative impingement, dislocation, and accelerated polyethylene wear. Computed tomography (CT)-based navigation systems provide accuracy for total hip arthroplasty (THA) but are not available in all facilities. Accelerometer-based navigation systems are inexpensive, but their accuracy remains undetermined. This study compares the accuracy of cup orientation in THA using CT-based and accelerometer-based navigation systems. Methods: This retrospective study included 35 consecutive patients (11 males, 24 females; mean age, 65 years) who underwent primary cementless THA via an anterolateral approach in the supine position. Both CT-based and accelerometer-based navigation systems were used simultaneously. The accuracy of cup orientation was compared between the two systems using postoperative CT. Results: The accuracy of cup inclination was 2.7° ± 2.0° in the CT-based group and 3.3° ± 2.4° in the accelerometer-based group. The accuracy of cup anteversion was 2.8° ± 2.6° in the CT-based group and 3.4° ± 2.2° in the accelerometer-based group. No significant difference was observed in cup inclination ( p = 0.29) or cup anteversion ( p = 0.34) between CT-based and accelerometer-based navigation. Conclusions: The accuracy of cup positioning did not differ significantly between CT-based and accelerometer-based navigation systems.

Computed Tomography-Based Patient-Specific Instrumentation Loses Accuracy with Significant Varus Preoperative Misalignment

2020 ◽  
Author(s):  
Vicente Jesús León-Muñoz ◽  
Mirian López-López ◽  
Alonso José Lisón-Almagro ◽  
Francisco Martínez-Martínez ◽  
Fernando Santonja-Medina
Keyword(s):  
Computed Tomography ◽  
Deformity Correction ◽  
Patient Specific ◽  
Control Group ◽  
X Rays ◽  
Varus Alignment ◽  
Patient Specific Instrumentation ◽  
Conventional Instrumentation ◽  
The Mean ◽  
Valgus Alignment

AbstractPatient-specific instrumentation (PSI) has been introduced to simplify and make total knee arthroplasty (TKA) surgery more precise, effective, and efficient. We performed this study to determine whether the postoperative coronal alignment is related to preoperative deformity when computed tomography (CT)-based PSI is used for TKA surgery, and how the PSI approach compares with deformity correction obtained with conventional instrumentation. We analyzed pre-and post-operative full length standing hip-knee-ankle (HKA) X-rays of the lower limb in both groups using a convention > 180 degrees for valgus alignment and < 180 degrees for varus alignment. For the PSI group, the mean (± SD) pre-operative HKA angle was 172.09 degrees varus (± 6.69 degrees) with a maximum varus alignment of 21.5 degrees (HKA 158.5) and a maximum valgus alignment of 14.0 degrees. The mean post-operative HKA was 179.43 degrees varus (± 2.32 degrees) with a maximum varus alignment of seven degrees and a maximum valgus alignment of six degrees. There has been a weak correlation among the values of the pre- and postoperative HKA angle. The adjusted odds ratio (aOR) of postoperative alignment outside the range of 180 ± 3 degrees was significantly higher with a preoperative varus misalignment of 15 degrees or more (aOR: 4.18; 95% confidence interval: 1.35–12.96; p = 0.013). In the control group (conventional instrumentation), this loss of accuracy occurs with preoperative misalignment of 10 degrees. Preoperative misalignment below 15 degrees appears to present minimal influence on postoperative alignment when a CT-based PSI system is used. The CT-based PSI tends to lose accuracy with preoperative varus misalignment over 15 degrees.

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