Magnetic resonance imaging based finite element modelling of the proximal femur: a short-term in vivo precision study.

Proximal femoral fractures are a serious life-threatening injury with high morbidity and mortality. Magnetic resonance (MR) imaging has potential to non-invasively assess proximal femoral bone strength in vivo through usage of finite element (FE) modelling (a technique referred to as MR-FE). To precisely assess bone strength, knowledge of measurement error associated with different MR-FE outcomes is needed. The objective of this study was to characterize the short-term in vivo precision errors of MR-FE outcomes (e.g., stress, strain, failure loads) of the proximal femur for fall and stance loading configurations using 13 participants (5 males and 8 females; median age: 27 years, range: 21-68), each scanned 3 times. MR-FE models were generated, and mean von Mises stress and strain as well as principal stress and strain were calculated for 3 regions of interest. Similarly, we calculated the failure loads to cause 5% of contiguous elements to fail according to the von Mises yield, Brittle Coulomb-Mohr, normal principal, and Hoffman stress and strain criteria. Precision (root-mean squared coefficient of variation) of the MR-FE outcomes ranged from 3.3% to 11.8% for stress and strain-based mechanical outcomes, and 5.8% to 9.0% for failure loads. These results provide evidence that MR-FE outcomes are a promising non-invasive technique for monitoring femoral strength in vivo.

Four-Corner Arthrodesis with a Dorsal Locking PEEK Plate: A Retrospective Case Series.

Background Four-corner arthrodesis (4CA) can be performed with a variety of methods. To our knowledge, fewer than 125 cases of 4CA with a locking polyether ether ketone (PEEK) plate have been reported, necessitating further study. Purpose The purpose of this study was to evaluate the radiographic union rate and clinical outcomes in a series of patients who received 4CA with a locking PEEK plate. Methods We re-examined 39 wrists in 37 patients at a mean follow-up of 50 months (median: 52 months, range: 6-128). Patients completed the Quick Disabilities of the Arm, Shoulder, and Hand (QuickDASH), Patient-Rated Wrist Evaluation (PRWE), and participated in measurements of grip strength and range of motion. Anteroposterior, lateral, and oblique radiographs of the operative wrist were examined for union, screw breakage and/or loosening, and lunate change. Results The mean QuickDASH score was 24.4 and the mean PRWE score was 26.5. Mean grip strength was 29.2 kg or 84% of the nonoperative hand. Mean flexion, extension, radial deviation, and ulnar deviation were : 37.2, 28.9, 14.1, and 17.4 degrees, respectively. Eighty-seven percent of wrists achieved union; 8% had nonunion; and5% had indeterminate union. There were seven cases of screw breakage and seven cases of screw loosening (as defined by lucency or bony resorption surrounding screws). Twenty-three percent of wrists required reoperation (four total wrist arthrodesis and five reoperations for other reasons). Conclusion 4CA with a locking PEEK plate has clinical and radiographic outcomes similar to other methods. We observed a high rate of hardware complications. It is unclear whether this implant offers a clear advantage over other methods of fixation used in 4CA. Type of Study/Level of Evidence Level IV, therapeutic study.

Correlation between superior humeral head migration and proximal long head of biceps tendon pathology in patients with and without rotator cuff tears using magnetic resonance imaging and radiography.

Background: The biomechanical role of the proximal long head of the biceps tendon (PLHB) in glenohumeral joint stability remains controversial. This retrospective study aims to correlate between humeral head migration and PLHB pathology in patients with and without rotator cuff tendon tears using imaging. Methods: Seventy-nine patients who underwent 3T magnetic resonance imaging of the shoulder were retrospectively reviewed. Imaging findings were documented by a fellowship-trained musculoskeletal radiologist. PLHB tendon diameter change, contour irregularity, and signal intensity change were assessed. Rotator cuff status was given a binary assignment of intact vs. torn. Radiographs were used for measurement of the acromiohumeral distance and a cutoff value of 7 mm was set as a lower limit of normal. Results: In the cohort of 79 shoulders, 41.8% (33/79) of patients had intact PLHB tendon and rotator cuff, 26.6% (21/79) demonstrated isolated PLHB tendon pathology, 13.9% (11/79) demonstrated isolated rotator cuff tears, and 17.7% (14/79) demonstrated concomitant PLHB tendon pathology and rotator cuff tears. Acromiohumeral distance was preserved in 97.0% (32/33) of patients with intact PLHB tendon and rotator cuff, 28.6% (6/21) of patients with isolated PLHB tendon pathology, 81.8% (9/11) of patients with isolated rotator cuff tears, and 14.3% (2/14) of patients with concomitant PLHB tendon pathology and rotator cuff tears (P < .0001). Conclusion: Results of this study have shown that a statistical correlation was present between superior humeral head migration and PLHB tendon pathology with or without rotator cuff tears, compared to rotator cuff pathology alone. Findings suggest that intact PLHB tendon plays an important role in glenohumeral stability.

Presentation at the Canadian Association of Radiologists Annual General Meeting Is Associated With Higher Likelihood of Publication of Canadian Radiology Resident Research Day Presentations.

Objective: Determine how many radiology resident research day projects are presented at the Canadian Association of Radiologists Annual Scientific Meeting (CAR ASM) and if presentation at the CAR ASM is associated with increased rates of publication. Methods: A database of radiology resident presentations from 2012 to 2017 research days at seven Canadian radiology programs was utilized. Each presenting resident was searched for in 2011-2019 CAR ASM books of abstracts to identify all CAR ASM presentations both related to and separate from their research day projects. These presentations were matched with resident research day presentations and their publication status. Descriptive statistical analysis and calculation of relative risk (RR) between publication of research day projects and presentation at CAR was performed. Results: 208 residents presented 288 projects at internal research days. 93 of the 208 residents had a total of 195 presentations at CAR (mean .94 +/- 1.91 SD). 36 of the 288 (13%) research day projects were presented at a CAR ASM, of which 18/36 (50%) were published. 83 of the 252 (32%) research day projects not presented at CAR were published. CAR ASM presentation of a research day project was associated with an increased rate of publication (RR 1.537 P=.0396). There was no significant association between research day project publication and unrelated CAR ASM presentations (P=.275). Most research day projects both presented at CAR ASM and published (56%) were in the Canadian Association of Radiologists Journal. Conclusion: CAR ASM presentation of research day projects is associated with an increased rate of publication.

Is Call Karma Real? Resident After-Hours On-Call Imaging at the University of Saskatchewan: An Assessment of Call Volumes Including Inter-Resident Variability.

PURPOSE: Quantify resident caseload during call and determine if there are consistent differences in call volumes for individuals or resident subgroups. METHODS: Accession codes for after-hours computed tomography (CT) cases dictated by residents between July 1, 2012 and January 9, 2017 were reviewed. Case volumes by patient visits and body regions scanned were determined and categorized according to time period, year, and individual resident. Mean shift Relative Value Units (RVUs) were calculated by year. Descriptive statistics, linear mixed modeling, and linear regression determined mean values, differences between residents, associations between independent variables and outcomes, and changes over time. Consistent differences between residents were assessed as a measure of good or bad luck / karma on call. RESULTS: During this time there were 23,032 patients and 30,766 anatomic regions scanned during 1,652 call shifts among 32 residents. Over the whole period, there were on average 10.6 patients and 14.3 body regions scanned on weekday shifts and 22.3 patients and 29.4 body regions scanned during weekend shifts. Annually, the mean number of patients, body regions, and RVUs scanned per shift increased by an average of 0.2 (1%), 0.4 (2%), and 1.2 (5%) (all p < 0.05) respectively in regression models. There was variability in call experiences, but only 1 resident had a disproportionate number of higher volume calls and fewer lower volume shifts than expected. CONCLUSIONS: Annual increases in scan volumes were modest. Although residents' experiences varied, little of this was attributable to consistent personal differences, including luck or call karma.

Incidence Rates of Surgery After Knee MRI: Association According to Referring Physician Type and Patient's Age and Sex.

BACKGROUND: The utility of magnetic resonance imaging (MRI) in the primary care setting is uncertain, with a perception that there is less likelihood for surgery after MRI ordered by general practitioners (GPs) when compared with orthopaedic surgeons and sports medicine physicians. Additionally, the influence of patient age and sex on subsequent surgical intervention is currently unknown. PURPOSE/HYPOTHESIS: The purpose of this study was to compare surgical incidence after MRI referrals by orthopaedic surgeons, GPs, and sports medicine physicians, including a subset analysis for GP patients based on type of approval given by the radiologist. The authors also wanted to explore the association of age and sex on subsequent surgical intervention. They hypothesized that surgical incidence after MRI ordered by orthopaedic surgeons and sports medicine physicians would be higher than after MRI ordered by GPs. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: Knee MRI referrals by the 3 physician cohorts during May to December 2017 were assessed. For GP patients, the types of approval or recommendation from a radiologist were categorized. Subsequent surgical intervention status was then compared among referral groups up to 2 years after MRI. Associations of age and sex with surgical occurrence were also assessed. Chi-square test, analysis of variance, and univariate/multivariable logistic regression were used for statistical analysis. RESULTS: Overall, 407 referrals were evaluated (GP, n = 173; orthopaedic, n = 176; sports medicine, n = 58). Surgical incidence was not significantly higher for orthopaedic and sports medicine than GP referrals at 3 months (10%, 3%, and 6%, respectively; P = .23), 6 months (20%, 17%, and 15%; P = .49), and 2 years (30%, 35%, and 24%; P = .25). Surgical incidence for GP patients was higher after discussion with a radiologist or when evaluating specific pathology on prior imaging versus less defined reasons (30.4% vs 15.7%, respectively; P = .03). Surgical incidence was lower for older patients (11% vs 31% for >60 years vs all other age groups combined; P = .002), and women were less likely to undergo surgery than men (22% vs 35%, respectively; P = .008). CONCLUSION: Surgical incidence after MRI was likely appropriately lower for older patients. Lower incidence for female patients is of uncertain cause and warrants further study.

Proximal femoral epiphyseal spurs and their association with acetabular labral tears on MRI in symptomatic patients.

OBJECTIVE: Femoral epiphyseal spurs are developmental projections that form at the edge of the physis. Although considered incidental, their association with acetabular labral tears has never been examined. Our aim was to assess the prevalence of femoral epiphyseal spurs in symptomatic patients with mechanical hip pain and explore if they are associated with labral tears on MRI. MATERIALS AND METHODS: Hip MRI scans performed on a Siemens 3 T MRI using femoroacetabular impingement protocol were retrospectively reviewed. All patients were referred by orthopaedic surgeons for mechanical hip pain. Two musculoskeletal radiologists blinded to initial reports evaluated MRI images for the presence of an epiphyseal spur and acetabular labral changes. A consensus was achieved on all cases by the two readers. The association between epiphyseal spurs and labral changes was assessed using Fisher's exact test. RESULTS: A total of 115 patients (178 hip MRI scans) were reviewed; the mean age was 28.8 years (SD 7.1). There were 52 females (45.2%) and 63 males (54.8%). There were 115 hips with labral tears (64.6%). Fourteen hips (7.8%) in ten patients (8.7%) demonstrated epiphyseal spurs and all of them showed labral tears (100%). There was statistically significant association between epiphyseal spurs and labral tears on MRI (p value = 0.0024). CONCLUSION: Femoral epiphyseal spurs were observed in 8.7% of our defined patient population, and all patients with epiphyseal spurs demonstrated labral tears. Epiphyseal spurs should be documented on imaging reports due to their potential association with labral tears. Future research is needed to further delineate and guide management of these entities.

Research on Research: Publication of Projects Presented at Medical Imaging Research Days Across Canada.

OBJECTIVE: Twenty-one previous studies have shown a mean presentation to publication conversion rates at radiology conferences of 26%. There have been no prior studies on publication of medical imaging residency research presentations. Our objective was to determine how many medical imaging resident research projects presented at internal program research days across Canada go on to publication. METHODS: A list of unique medical imaging resident research presentations given at program research days during the 2012-2013 to 2016-2017 academic years was generated via e-mail contact of programs or review of publicly available data on program websites. Unique resident presentations were identified and publications associated with these presentations were sought via database and Internet searching. The number of publications, publishing journals, and time to publication was determined. RESULTS: Data from 32 research days at 7 programs were assessed. A total of 287 resident presentations were identified. Of these 287 presentations, 99 had associated publications (34% presentation to publication conversation rate), with variation in presentation numbers and publication conversion rates between schools. These 99 presentations were associated with a total of 118 publications in a total of 57 different journals. Time from presentation to publication was calculable for 109 of the 118 articles. Fifteen (14%) were published before research day and 94 (86%) were published after research day with a mean time to publication of 12.3 ± 13.6 months for all articles. CONCLUSIONS: Thirty-four percent of resident research presentations at Canadian medical imaging program research days go on to publication.

Endoclip Magnetic Resonance Imaging Screening: A Local Practice Review.

PURPOSE: Not all endoscopically placed clips (endoclips) are magnetic resonance imaging (MRI) compatible. At many institutions, endoclip screening is part of the pre-MRI screening process. Our objective is to determine the contribution of each step of this endoclip screening protocol in determining a patient's endoclip status at our institution. METHODS: A retrospective review of patients' endoscopic histories on general MRI screening forms for patients scanned during a 40-day period was performed to assess the percentage of patients that require endoclip screening at our institution. Following this, a prospective evaluation of 614 patients' endoclip screening determined the percentage of these patients ultimately exposed to each step in the protocol (exposure), and the percentage of patients whose endoclip status was determined with reasonable certainty by each step (determination). RESULTS: Exposure and determination values for each step were calculated as follows (exposure, determination): verbal interview (100%, 86%), review of past available imaging (14%, 36%), review of endoscopy report (9%, 57%), and new abdominal radiograph (4%, 96%), or CT (0.2%, 100%) for evaluation of potential endoclips. Only 1 patient did not receive MRI because of screening (in situ gastrointestinal endoclip identified). CONCLUSIONS: Verbal interview is invaluable to endoclip screening, clearing 86% of patients with minimal monetary and time investment. Conversely, the limited availability of endoscopy reports and relevant past imaging somewhat restricts the determination rates of these. New imaging (radiograph or computed tomography) is required <5% of the time, and although costly and associated with patient irradiation, has excellent determination rates (above 96%) when needed.

Endoscopic Clip MRI Screening: A Canada-Wide Policy Survey.

OBJECTIVE: Not all endoscopically placed clips are MRI compatible, so screening for endoscopic clips before MRI is recommended. The purpose of this study was to assess endoscopic clip screening practices at Canadian MRI centers, including number of centers that screen, specific screening methods, perceived safety of endoscopic clip models, and practices for dealing with confirmed gastrointestinal endoscopic clips. MATERIALS AND METHODS: A bilingual online survey was distributed to Canadian MRI centers to assess site demographics, endoscopic clip screening practices, safety considerations for different endoscopic clip models, protocols for dealing with patients with endoscopic clips, and the perceived value of screening. One year later, a secondary survey was distributed to the original participants to assess for changes made to screening policy after the initial survey and to assess awareness of any complications arising from the presence of endoscopic clips during MRI. RESULTS: Sixty-seven MRI centers completed the survey (55% response rate). Sixteen centers (24%) did not specifically screen for endoscopic clips, five because they were not aware that endoscopic clips may not be safe for MRI. Fifty-one centers (76%) did screen for endoscopic clips. At least 23% of screeners misclassified the safety of one or more MRI-unsafe clips. As many as 36% of screeners may perform MRI on patients with confirmed gastrointestinal endoscopic clips; 16% reschedule for more than 6 weeks after endoscopy; and 18% limit the field strength to 1.5 T, the safety of which is uncertain. CONCLUSION: Many Canadians are undergoing MRI without screening for endoscopic clips. Although the risks of MRI to patients with endoscopic clips is unclear, the misclassification of some endoscopic clip models and inconsistent protocols for dealing with confirmed endoscopic clips call for further research and unified evidence-based endoscopic clip screening standards.

The role of radiology in the quantification of digital ulnar deviation in rheumatoid arthritis patients.

BACKGROUND: Rheumatoid arthritis (RA) is a common inflammatory polyarthritis, which causes functional digital ulnar deviation (UD). Radiographic and magnetic resonance imaging (MRI) assessment of the hands is essential in RA, but its role in the quantification of UD remains unclear. PURPOSE: To compare UD measurements in RA patients between clinical goniometric assessments versus standardized radiographs and MRI. METHODS: Fifteen RA patients with clinically apparent UD and 11 RA patients without UD underwent a rheumatological examination prior to recruitment to this study. Goniometric measurements for UD at the metacarpophalangeal (MCP) joints were performed by an occupational therapist (OT). Standardized hand radiographs, and MRI studies of the dominant hand using 3T MRI scanner with 16 channel hand/wrist coil were evaluated. Angulation measurements for radiographs and MRI were performed independently by two experienced musculoskeletal radiologists who were blinded to the rheumatologist's, occupational therapist's and each other's assessments. RESULTS: Inter-observer correlation between radiologists was >0.97 for both radiographic and MRI measurements. Correlation between OT goniometric measurements and the imaging-based measurements was limited at 0.496 for radiographs and 0.317 for MRI. Correlation between imaging modalities was 0.513. Compared to OT measurements, radiographic and MRI study measurements significantly underestimate the angulation in RA patients with UD (P < 0.001). CONCLUSIONS: The results of this study demonstrated discordance between radiological and goniometric measurements of digital ulnar angulation at the MCP joints in RA patients. Although imaging plays a key role in understanding structural damage and disease activity in RA, it should be emphasized that radiological measurements underrate joint malalignment.

Knowing the Enemy: Health Care Provider Knowledge of Computed Tomography Radiation Dose and Associated Risks.

BACKGROUND: There is ionizing radiation and associated risk from many medical imaging examinations, especially computed tomography (CT). Unfortunately, health care providers often have limited knowledge regarding radiation dose levels and potential risk. RESEARCH OBJECTIVES: To assess knowledge of dose levels and risk among referring physicians, imaging technologists, and radiologists in Saskatoon, Saskatchewan, and to identify potential differences between and within those groups. MATERIALS AND METHODS: A survey was designed and administered to health care professionals. RESULTS: A total of 308 of 328 surveys were completed (91% response rate). Overall 73% of physicians, 97% of radiologists, and 76% of technologists correctly believed that there is a risk for cancer from an abdomen-pelvic CT scan. Although only 18% of physicians, 28% of radiologists, and 22% of technologists selected the most appropriate estimate of abdominal-pelvic CT dose in terms of chest x-ray equivalents, this is similar to other reported studies. Physicians and technologists who use CT were more likely to select the correct dose than those who do not. Most respondents (91% of physicians, 100% of radiologists, and 100% of technologists) felt that pregnant patients should always be informed about radiation dose as a risk. Although frequency of discussing risk decreased with increasing patient age, technologists were more likely to discuss risk at any age. A total of 93% of respondents expressed interest in receiving dose feedback from medical imaging procedures. CONCLUSIONS: Radiologists and technologists generally showed better knowledge than referring physicians. Among physicians and technologists, knowledge was better in those who use CT than those who do not.

Radiological errors in the Canadian Journal of Emergency Medicine.

OBJECTIVES: To systematically evaluate the accuracy of text descriptions and labeling of radiologic images published in the Canadian Journal of Emergency Medicine (CJEM). Error detection by radiologists and emergency physicians and the clinical significance and educational value of these errors were assessed. Errors were also correlated with radiologist involvement in publication and imaging modality. METHODS: Thirty-three issues of CJEM were examined from January 2003 to May 2008. Electronic copies of all radiologic images published were obtained with their caption and description from the text. Identifying information was removed to present images in an anonymous fashion. Images were presented to two radiologists who, working in consensus, critically appraised each image and accompanying text. Images were then presented to two emergency department physicians who, working in consensus, critically appraised each image and accompanying text. All images with errors detected by either radiology or emergency physicians were then discussed to determine if errors would have affected clinical management or educational value. The emergency physicians also identified "underlabeled" images where it was felt that further labeling would enhance their educational value. RESULTS: Forty-five articles with 82 images were obtained. At least one error was observed in 18 (40%) articles and 20 (24%) images. Two errors were present in three images, resulting in 23 errors. Of the 23 errors, 17 were image description errors and 6 were labeling errors. Five errors were detected by both radiology and emergency physicians, whereas 15 were detected only by radiologists and 3 were detected only by emergency physicians. Of these errors, 12 (52%) were rated as potentially affecting both clinical management and educational value, 5 (22%) as only affecting educational value, and 6 (26%) as nonsignificant. Radiologists were involved in six articles, including 12 images that contained no errors. There was no official radiologist involvement in 39 articles, including 70 images, 18 (26%) of which contained errors. In addition, 26 images were identified by emergency physicians as potentially benefiting from enhanced labeling to improve educational value. CONCLUSIONS: Radiologic images published in the CJEM are generally of high quality; however, 23 errors were found in 82 images, 18 (78%) of which were rated as potentially affecting clinical management, educational value, or both. Radiologist involvement in the publication process may be of assistance as no errors were seen in articles that included radiologists as authors.

Fetal shielding combined with state of the art CT dose reduction strategies during maternal chest CT.

PURPOSE: Custom bismuth-antimony shields were previously shown to reduce fetal dose by 53% on an 8DR (detector row) CT scanner without dynamic adaptive section collimation (DASC), automatic tube current modulation (ATCM) or adaptive statistical iterative reconstruction (ASiR). The purpose of this study is to compare the effective maternal and average fetal organ dose reduction both with and without bismuth-antimony shields on a 64DR CT scanner using DASC, ATCM and ASiR during maternal CTPA. MATERIALS AND METHODS: A phantom with gravid prosthesis and a bismuth-antimony shield were used. Thermoluminescent dosimeters (TLDs) measured fetal radiation dose. The average fetal organ dose and effective maternal dose were determined using 100 kVp, scanning from the lung apices to the diaphragm utilizing DASC, ATCM and ASiR on a 64DR CT scanner with and without shielding in the first and third trimester. Isolated assessment of DASC was done via comparing a new 8DR scan without DASC to a similar scan on the 64DR with DASC. RESULTS: Average third trimester unshielded fetal dose was reduced from 0.22 mGy ± 0.02 on the 8DR to 0.13 mGy ± 0.03 with the conservative 64DR protocol that included 30% ASiR, DASC and ATCM (42% reduction, P<0.01). Use of a shield further reduced average third trimester fetal dose to 0.04 mGy ± 0.01 (69% reduction, P<0.01). The average fetal organ dose reduction attributable to DASC alone was modest (6% reduction from 0.17 mGy ± 0.02 to 0.16 mGy ± 0.02, P=0.014). First trimester fetal organ dose on the 8DR protocol was 0.07 mGy ± 0.03. This was reduced to 0.05 mGy ± 0.03 on the 64DR protocol without shielding (30% reduction, P=0.009). Shields further reduced this dose to below accurately detectable levels. Effective maternal dose was reduced from 4.0 mSv on the 8DR to 2.5 mSv on the 64DR scanner using the conservative protocol (38% dose reduction). CONCLUSION: ASiR, ATCM and DASC combined significantly reduce effective maternal and fetal organ dose during CTPA. Shields continue to be an effective means of fetal dose reduction.

Increasing lateral tibial slope: is there an association with articular cartilage changes in the knee?

PURPOSE: The geometry of the lateral tibial slope (LTS) plays an important role in the overall biomechanics of the knee. Through this study, we aim to assess the impact of LTS on cartilage degeneration in the knee. MATERIALS AND METHODS: A retrospective analysis of 93 knee MRI scans (1.5 T or 3 T) for patients aged 20-45 years with no history of trauma or knee surgery, and absence of internal derangement. The LTS was calculated using the circle method. Chondropathy was graded from 0 (normal) to 3 (severe). Linear regression analysis was used for statistical analysis (p < 0.05). RESULTS: In our cohort of patients, a statistically significant association was seen between increasing LTS and worsening cartilage degenerative changes in the medial patellar articular surface and the lateral tibial articular surface (p < 0.05). There was no statistically significant association between increasing LTS and worsening chondropathy of the lateral patellar, medial trochlea, lateral trochlea, medial femoral, lateral femoral, and medial tibial articular surfaces. CONCLUSIONS: Our results show a statistically significant association between increasing LTS and worsening cartilage degenerative changes in the medial patella and the lateral tibial plateau. We speculate that increased LTS may result in increased femoral glide over the lateral tibial plateau with subsequent increased external rotation of the femur predisposing to patellofemoral articular changes. Future arthroscopic studies are needed to further confirm our findings.

Comparison of short-term in vivo precision of bone density and microarchitecture at the distal radius and tibia between postmenopausal women and young adults.

The purpose was to assess whether precision of bone properties derived via the use of high-resolution peripheral quantitative computed tomography (HR-pQCT) differs between postmenopausal women and young adults. Using HR-pQCT, we scanned the distal radius and tibia at 2 time points in 34 postmenopausal women (74 ± 7 years) and 30 young adults (mean age ± SD: 27 ± 9 years). Standard protocols were used to acquire bone area, density, and microarchitectural properties. We calculated coefficients of variation (CV; percentage CV and percentage CV of the root mean square) and 95% limits of agreement (95% LOA) to assess precision errors. The 95% LOA is the magnitude of individual change needed to be observed to ensure that a real change has occurred. Multiple Mann-Whitney U-tests (with the use of Bonferroni correction for multiple comparisons) were used to compare percentage CV between the 2 groups. Significance was set to p < 0.004. All standard outcome variables were not significantly different between the groups. The 95% LOA confirmed that the measurement bias between the groups did not differ. These results suggest that short-term precision errors in HR-pQCT-derived bone outcomes are similar between postmenopausal women and young adults.

Case study: chronic recurrent multifocal osteomyelitis in the femoral diaphysis of a young female.

Chronic recurrent multifocal osteomyelitis (CRMO) is relatively uncommon. Even though the name suggests it is the result of infection, this is not likely the case. Instead it is more likely the result of genetic, autoimmune, or autoinflammatory causes. Although CRMO has a benign course and responds well to anti-inflammatory medications, it can have a very aggressive clinical and imaging presentation overlapping with infectious osteomyelitis and malignancy. Therefore, radiologists and clinicians need to be aware of its clinical and imaging presentation to avoid morbidity associated with more aggressive treatment. We present the case of a ten-year-old female with CRMO as a solitary expansile-mixed lytic and sclerotic lesion in the distal femoral diaphysis. The diaphyseal location and mixed lytic and sclerotic appearance are less common and have an aggressive imaging appearance. We also review the pathophysiology, imaging findings, and therapeutic approach to this uncommon but clinically important condition.

Changing radiation dose from diagnostic computed tomography examinations in Saskatchewan.

PURPOSE: Follow-up study to observe if provincial mean effective radiation dose for head, chest, and abdomen-pelvis (AP) computed tomographies (CTs) remained stable or changed since the initial 2006 survey. METHODS: Data were collected in July 2008 from Saskatchewan's 13 diagnostic CT scanners of 3358 CT examinations. These data included the number of scan phases and projected dose length product (DLP). Technologists compared projected DLP with 2006 reference data before scanning. Projected DLP was converted to effective dose (ED) for each head, chest, and AP CT. The total dose that the patients received with scans of multiple body parts at the same visit also was determined. RESULTS: The mean (± SD) provincial ED was 3.4 ± 1.6 mSv for 1023 head scans (2.7 ± 1.6 mSv in 2006), 9.6 ± 4.8 mSv for 588 chest scans (11.3 ± 8.9 mSv in 2006), and 16.1 ± 9.9 mSv for 983 AP scans (15.5 ± 10.0 mSv in 2006). Single-phase multidetector row CT ED decreased by 31% for chest scans (9.5 ± 3.9 mSv vs 13.7 ± 9.7 mSv in 2006) and 17% for AP scans (13.9 ± 6.0 mSv vs 16.8 ± 10.6 mSv in 2006) and increased by 19% for head scans (3.2 ± 1.2 mSv vs 2.7 ± 1.5 mSv in 2006). The total patient dose was highest (33.8 ± 10.1 mSv) for the 20 patients who received head, neck, chest, and AP scans during a single visit. Because of increased utilisation and the increased CT head dose, Saskatchewan per capital radiation dose from CT increased by 21% between 2006 and 2008 (1.14 vs 1.38 mSv/person per year). CONCLUSION: Significant dose and variation reduction was seen for single-phase CT chest and AP examinations between 2006 and 2008, whereas CT head dose increased over the same interval. These changes, combined with increased utilisation, resulted in per capita increase in radiation dose from CT between the 2 studies.

Lead versus bismuth-antimony shield for fetal dose reduction at different gestational ages at CT pulmonary angiography.

PURPOSE: To compare the effective fetal dose reduction at different stages of gestation during maternal computed tomographic (CT) pulmonary angiography by using traditional lead apron and bismuth-antimony shields combined with limited z-axis and tube current. MATERIALS AND METHODS: Phantom with gravid prosthesis, 0.5-mm lead, and two grades of bismuth-antimony shield was used. Thermoluminescent dosimeters (TLDs) measured radiation in the first- to third-trimester uterus. Fetal dose was determined for each gestation by using 100 kVp to the costophrenic angles (CPAs) with and without shielding for a total of 12 scans. Eight third-trimester scans were used to compare shields using 120 kVp to CPAs versus those using 100 kVp to the diaphragm. RESULTS: Average fetal dose increased with gestation with use of 100 kVp to CPAs, from 0.11 mGy in first trimester to 0.50 mGy in third trimester. Average third-trimester unshielded fetal dose was reduced from 0.82 mGy by using 120 kVp to CPAs to 0.17 mGy (79%, P < .001) by using 100 kVp to the diaphragm. Lead apron reduced dose more than either of the bismuth-antimony shields (72%-79% vs 57%-81%) with use of 100 kVp to CPAs. Shields reduced the dose by 73% (lead), 62% (90% attenuation bismuth-antimony), and 72% (95% attenuation bismuth-antimony) (P < .01) at 120 kVp to CPAs. No significant difference between shields was demonstrated with 100 kVp to the diaphragm (P < .01). Maternal dose was 8.13 mSv at 120 kVp to CPAs, 4.90 mSv at 100 kVp to CPAs, and 4.02 mSv at 100 kVp to the diaphragm. CONCLUSION: Reducing voltage and limiting z-axis is more effective than shields at reducing fetal dose. Shielding improves reduction with no significant difference between lead and bismuth-antimony shields when conservative scanning parameters are observed.