A Novel Fluoroscopic Approach to Assessing Patient Positioning in Total Hip Arthroplasty: Accuracy and the Influence of Body Mass Index
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Accurate prosthetic cup placement is important in total hip arthroplasty (THA) and can be influenced by patient positioning. This study aims to assess the accuracy of patient positioning prior to THA, describe a new technique of assessment, and evaluate the influence of body mass index (BMI) on positioning error.A consecutive series of 37 patients undergoing unilateral THA were investigated. After patient positioning in lateral decubitus, a lateral fluoroscopic image through the table was taken. The C-arm of the image intensifier was manipulated in 2 planes (coronal, transverse) until a perfect lateral view of the pelvis was obtained, defined as when the native acetabulae were superimposed. Degrees of positioning error in the 2 planes were recorded, along with patient BMI.There were 6 patients (16%) positioned within 2° of true lateral in both planes. A further 21 patients (57%) had an error of 5° or more in at least 1 plane. Mean absolute positioning error was 3.0° (SD 2.2°; range 0°-9°) and 3.0° (SD 3.2°; range 0°-13°) in the transverse and coronal planes respectively. Pelvic adduction in the coronal plane was 4.5 fold more likely than abduction (49% vs. 11%). Correlation was shown between patient BMI and the combined error in the 2 planes (R = 0.48, p = 0.001).Fluoroscopic positioning assessment prior to THA demonstrates that significant malpositioning is common and more likely with increasing BMI. This technique may be particularly useful for patients with a BMI of >30 kg m-2.Radiation awareness has been advocated as a method of decreasing radiation exposure. For fluoroscopy, one indicator of radiation use is fluoroscopy time. We retrospectively reviewed fluoroscopy times on voiding cystourethrography (VCUG) studies performed at a major pediatric center, comparing the average fluoroscopy time of examinations with the fluoroscopy time documented in the report to the average time of those without documentation.A database search of records for the period between June 1, 2002, and March 31, 2009, identified all VCUG examinations and their recorded fluoroscopy time in the radiology information system. Those examinations in which the fluoroscopy time was documented in the radiologist's report were also identified. Average fluoroscopy times were calculated for three groups: all VCUG examinations, examinations without the fluoroscopy time documented in the dictated report, and examinations including the fluoroscopy time in the dictated report.Over the 7-year study period, 10,594 VCUG examinations were performed. The average fluoroscopy time was 47 seconds for all examinations, 50 seconds for examinations without fluoroscopy time reported (n = 8484), and 32 seconds for examinations with fluoroscopy time reported (n = 1979). There was a statistically significant difference between examinations with and without fluoroscopy time reported by the radiologist (p < 0.0001). A decreasing trend in average fluoroscopy time for all VCUG examinations was identified over time (average fluoroscopy time: 65 seconds for 2002-2003 vs 29 seconds for 2008-2009). Radiologists also increasingly reported fluoroscopy time over time (fluoroscopy time reported in 1% of reports in 2002-2003 vs 82% in 2008-2009).Radiologist reporting of fluoroscopy time correlates with a decrease in fluoroscopy time, a surrogate indicator of radiation dose. Our findings suggest that the radiologist's documentation of fluoroscopy time in the report is part of a radiation awareness strategy leading to decreased fluoroscopy times.
Cystourethrography
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Abstract Background Although the relatively high incidence of coronal fractures in the supracondylar–intercondylar fractures is well established, little is currently known about the morphology of those fractures. Herein, we characterized the coronal fractures in AO/OTA type 33-C3 and assessed their differences with Busch–Hoffa fractures (33-B3). Methods We retrospectively collected 61 cases of AO/OTA type 33-B or C fractures with coronal plane fragments and generated three-dimensional fracture maps of those with coronal fractures based on CT imaging and measured angle α (the angle between the coronal fracture and the posterior condyle axis in the axis plane) and angle β (the angle between the coronal fracture and the posterior femoral cortex in the sagittal plane). Results Thirty-three cases (32%) of AO/OTA type 33-C fractures contained coronal fragments. Most of them were type 33-C3 fractures. Angles α and β for type 33-C3 were significantly smaller than for type B3 at the lateral condyle, while the angles at the medial condyle were not significantly different. The fracture maps showed that the coronal fractures and the articular comminution area were more anterior in type 33-C3. Conclusions The incidence of coronal fractures was 32% and 67% in AO/OTA types 33-C and 33-C3, respectively. Our findings suggest that coronal fractures differed between both types, emphasizing the potential need for different treatment approaches.
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Abstract Objectives : To investigate whether pulsed fluoroscopy reduces a patient's exposure compared with the exposure owing to conventional (continuous) fluoroscopy, we simulated the skin radiation doses of patients at cardiac catheterization facilities with various X‐ray systems used in fluoroscopically guided intervention procedures. Background : Although many reports have noted that “pulsed fluoroscopy” provides important further reductions in radiation exposure, it has been determined that when comparing dose rates between different vendor systems, “pulsed fluoroscopy” does not reduce patients' exposure as compared with “conventional fluoroscopy”. Methods : We examined 13 X‐ray systems; 10 used pulsed fluoroscopy and three used conventional fluoroscopy. The entrance surface doses with fluoroscopy were compared for the 13 X‐ray systems by using acrylic plates (20‐cm thick) and a skin dose monitor. The X‐ray conditions used in the measurements were those normally used in the facilities performing percutaneous coronary intervention. Results : The average surface dose for systems from three different vendors producing conventional fluoroscopy systems was 23.93 ± 2.77 mGy/min vs. an average surface dose of 22.52 ± 4.50 mGy/min from five vendors of pulsed fluoroscopy systems (25, 30, and 50 pulses/sec) ( P = 0.646). The average entrance surface dose was significantly ( P < 0.0001) higher with conventional fluoroscopy and pulsed fluoroscopy at 25, 30, and 50 pulses/sec (23.05 ± 3.78 mGy/min) than with pulsed fluoroscopy at 15 pulses/sec (13.86 ± 3.22 mGy/min). Conclusions : Pulsed fluoroscopy did not in itself reduce radiation exposure. In general, the use of pulsed fluoroscopy at a pulse rate lower than 25 pulses/sec should reduce the skin dose in fluoroscopically guided intervention procedures. Nevertheless, some X‐ray systems are not designed to reduce the dose rate as the number of pulses per second is decreased. Physicians should be aware of the entrance surface dose of the X‐ray system that they use for cardiac IVR. © 2006 Wiley‐Liss, Inc.
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Objective To study the value of single row spiral CT in multi-aspect scanning in patients with traumatic wrist joint.Methods A total of 76 patients with wrist trauma underwent conventional X-ray and spiral CT(including transverse plane,coronal plane and sagittal plane)examinations.Different azimuth imaging data acquired in all patients were compared.Results A total of 98 fractures and 10 dislocations were found.There were significant differences on the detection rates between X-ray and transverse plane,coronal plane and sagittal plane(χ2=4.248,9.960,14.430;P=0.035,0.002,0.000).There were no significant differences on the detection rates between transverse plane and coronal plane,between transverse plane and sagittal plane(χ2=3.070,P=0.251;χ2=1.260,P=1.030).Conclusion Different scanning azimuth could supplement each other,improve the accuracy of diagnosis,and provide a more comprehensive imaging basis for clinical diagnosis.
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Cardiac Ablation
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In Brief Study Design. Experimental and analytical study of transverse plane pelvic rotation. Objectives. To determine how pelvic rotation projected onto the transverse plane relates to coronal plane anatomic landmark location. Summary of Background Data. Current spine deformity instrumentation may be used to apply transverse plane loads to the spine that may be transmitted to regions not included in the instrumentation, including the pelvis. Methods. An anatomically correct, sawbones model of an adult female pelvis was marked with lead shot at prominent radiographic landmarks, rotated at different angles in the sagittal, transverse, and coronal planes, and left/right (L/R) ratios of the medial-lateral distances between similar landmarks determined. An analytical equation was also derived to determine the degree of rotation in the transverse plane, using medial-lateral and anterior-posterior distances between same landmarks. Results. The L/R ratio for the coronal plane distance between the inferior ilium at the sacro iliac joint (SI) and anterior superior iliac spine (ASIS), the SI-ASIS measurement, proved the most reliable of the four ratios studied to determine the extent of pelvic rotation in the transverse plane. Assuming the pelvis is symmetric, the most important factor is location of the compared landmarks. A long distance between the landmarks in both the coronal and transverse plane and a large angle between the line joining the two landmarks and the coronal plane of the pelvis, as viewed in the transverse plane, are best. Transverse plane pelvic rotation up to 20° is accurately reflected nearly linearly by L/R SI-ASIS ratios. Conclusions. Bony pelvis landmarks visible on coronal plane radiographs can be used to estimate transverse plane pelvic rotation, but precise conversion to degrees rotation requires additional information on specific patient pelvic morphology. Transverse plane pelvic rotation can be estimated using a left/right ratio of distances between readily identifiable medial and lateral radiographic landmarks visible on a coronal plane radiograph. More precise quantification requires determination of the transverse plane orientation of these medial and lateral landmarks.
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Study Design. Cadaveric in vitro computed tomography (CT) imaging study. Objective. To examine minimum pedicle diameter from transverse and coronal CT reconstructions of thoracolumbar spine specimens and compare their degree of disparity, if any. Pedicle angulation in coronal and transverse planes was measured and their contribution to the disparity in minimum pedicle diameter was assessed. Summary of Background Data. Spinal minimum pedicle diameter can be obtained from both transverse and coronal CT reconstructions; however, the degree of disparity in these measurements has not been described previously. Angulation of the pedicle in transverse and coronal planes may contribute to a disparity in minimum pedicle diameter acquired from reconstructions. This also has not been described previously. This study examined whether the disparity could be predicted by spinal level, as pedicle angulations vary in both coronal and transverse planes. Methods. Five thoracolumbar specimens (T1-L5, age 48–59 yrs, male) were CT scanned utilizing clinical protocols. Minimum pedicle diameters and pedicle angulations were acquired in transverse and coronal reconstructions. Disparities between minimum pedicle diameters were measured and the correlation between this disparity and spinal level was characterized. Results. A significant difference ( P < 0.001) in minimum pedicle diameter existed between measures from coronal and transverse reconstructions. There was a significant correlation ( P < 0.001) between the difference in minimal pedicle diameter and the transverse pedicle angle as well as the coronal pedicle angle. Conclusion. An overestimation of minimum pedicle diameter in the transverse reconstruction occurs when the coronal pedicle angulation increases, and in the coronal reconstruction when the transverse pedicle angulation increases. Therefore, pedicle angle should be determined using both coronal and transverse reconstructions and utilized to reduce the risk of overestimation of the true pedicle diameter. Level of Evidence: NA
Transverse diameter
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Although percutaneous fixation with iliosacral screws has been shown to be a safe and reproducible method for sacroiliac dislocation and sacral fractures, it is a technically demanding technique, and one of its contraindications is sacral anatomical variations and dysmorphism. The incidence and pattern of S1 and S2 anatomical variations were evaluated in 61 patients (35 women and 26 men) using magnetic resonance imaging of the sacrum in an attempt to explore the possible existence of groups of individuals in whom percutaneous sacroiliac fixation is difficult due to local anatomy. S1 and S2 dimensions in both the transverse and coronal planes were recorded and evaluated. In each individual, S1 and S2 dimensions both in the coronal and transverse planes were proportional, with S2 dimensions being 80% of those of S1 on average. Patients were separated into 4 groups based on the S1 and S2 body size and the asymmetry of dimensions in the transverse and coronal planes. In 48 patients (78.6%), dimensions in both planes were symmetrical despite the varying size of the S1 and S2 body. In 2 patients (3.3%) there was a combination of large transverse plane and small coronal plane dimensions, with large S1 and S2 body size. In 9 patients (14.8%), coronal plane dimensions were disproportionately smaller compared to those of the transverse plane, with a varying size of S1 and S2 body making effective sacroiliac screw insertion a difficult task. Thus, a preoperative imaging study, preferably computed tomography scan, of S1 and S2 body size and coronal plane dimensions and an intraoperative fluoroscopic control of S1 and S2 dimensions on the coronal plane are suggested for safe sacroiliac screw fixation.
Sacroiliac joint
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The purpose of this study was to determine if pulsed fluoroscopy reduces radiation exposure to pediatric patients undergoing conventional fluoroscopy. Four hundred one consecutive patients were nonrandomly divided into pulsed fluoroscopy and conventional fluoroscopy study groups. Two control groups were also assembled: 474 patients evaluated with conventional fluoroscopy before the study and 138 patients evaluated with pulsed fluoroscopy after the study. We found no difference in fluoroscopy times across the groups. Although the number of digital spot films was slightly higher for the pulsed fluoroscopy study group than for the conventional fluoroscopy study group, we found no difference in the number of digital spot films for the pulsed fluoroscopy study group and for the conventional fluoroscopy control group. Furthermore, the difference in the number of digital spot films was also insignificant for the pulsed fluoroscopy control group and the conventional fluoroscopy study group. The radiation exposure in the pulsed fluoroscopy study group was 50% lower (mean, 0.6 R) than in the conventional fluoroscopy study group. When using pulsed fluoroscopy in the 7.5 pulses-per-second mode, we were able to reduce radiation exposure by 75% of that from conventional fluoroscopy. Pulsed fluoroscopy reduces fluoroscopic radiation exposure to pediatric patients undergoing conventional fluoroscopy. Despite minor image degradation, pulsed fluoroscopy is the technique of choice at our institution.
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