Spatial Resolution Fidelity Comparison Between Energy Integrating and Deep Silicon Photon Counting CT: Implications for Pulmonary Imaging.

PURPOSE: We investigated spatial resolution loss away from isocenter for a prototype deep silicon photon-counting detector (PCD) CT scanner and compare with a clinical energy-integrating detector (EID) CT scanner. MATERIALS AND METHODS: We performed three scans on a wire phantom at four positions (isocenter, 6.7, 11.8, and 17.1 cm off isocenter). The acquisition modes were 120 kV EID CT, 120 kV high-definition (HD) EID CT, and 120 kV PCD CT. HD mode used double the projection view angles per rotation as the "regular" EID scan mode. The diameter of the wire was calculated by taking the full width of half max (FWHM) of a profile drawn over the radial and azimuthal directions of the wire. Change in wire diameter appearance was assessed by calculating the ratio of the radial and azimuthal diameter relative to isocenter. t tests were used to make pairwise comparisons of the wire diameter ratio with each acquisition and mean ratios' difference from unity. RESULTS: Deep silicon PCD CT had statistically smaller (P<0.05) changes in diameter ratio for both radial and azimuthal directions compared with both regular and HD EID modes and was not statistically different from unity (P<0.05). Maximum increases in FWMH relative to isocenter were 36%, 12%, and 1% for regular EID, HD EID, and deep silicon PCD, respectively. CONCLUSION: Deep silicon PCD CT exhibits less change in spatial resolution in both the radial and azimuthal directions compared with EID CT.

Sonographic evaluation of the association between calcific tendinopathy and rotator cuff tear: a case-controlled comparison.

OBJECTIVES: To compare the incidence of rotator cuff (RC) tears on shoulder ultrasounds of patients with RC calcific tendinopathy (CaT) to that of a control group without CaT. METHOD: In this retrospective case-control study, 50 shoulder ultrasounds of patients with CaT were compared independently by 2 musculoskeletal radiologists to 50 patients from a control group without CaT to catalog the number and type of RC tears. RC tears in the CaT group were further characterized based on location, into tears in the specific tendon(s) containing calcium versus all tendon tears. RESULTS: RC tears were diagnosed in 38% (19/50) of the control group (16 full-thickness) as compared to 22% (11/50) with CaT (6 full-thickness). The fewer full-thickness tears in the CaT group (12%, 6 of 50) compared to that in the control group (32%, 16 of 50) was statistically significant (P = 0.016, odds ratio 0.29). Only 7 of the 11 tears in the CaT group were in a calcium-containing tendon (3 full-thickness). The fewer calcium-containing tendon tears compared to tears in the control group was also statistically significant (P = 0.006, odds ratio 0.27). Furthermore, the fewer full-thickness calcium-containing tendon tears (6%, 3/50) compared to full-thickness tears in the control group (32%, 16/50) were yet more statistically significant (P = 0.001, odds ratio 0.14). CONCLUSIONS: In patients with shoulder pain and CaT, we observed a decreased number of RC tears and especially calcium-containing tendon tears, as compared to similar demographic patients with shoulder pain but without CaT. Key Points • Patients with rotator cuff calcific tendinopathy have few rotator cuff tears, especially full-thickness tears, compared to a control group without calcific tendinopathy. • The tendons containing the calcium hydroxyapatite deposition were the least likely to have a rotator cuff tear. • Future studies could evaluate if calcium hydroxyapatite deposition provides a protective mechanism against rotator cuff tears. • Musculoskeletal ultrasound is more sensitive than MRI in the evaluation of rotator cuff calcific tendinopathy.

CT analysis of anatomical distribution of melorheostosis challenges the sclerotome hypothesis.

Melorheostosis (MEL) is a rare disease of high bone mass with patchy skeletal distribution affecting the long bones. We recently reported somatic mosaic mutations in MAP2K1 in 8 of 15 patients with the disease. The unique anatomic distribution of melorheostosis is of great interest. The disease remains limited to medial or lateral side of the extremity with proximo-distal progression. This pattern of distribution has historically been attributed to sclerotomes (area of bone which is innervated by a single spinal nerve level). In a further analysis of our study on MEL, 30 recruited patients underwent whole body CT scans to characterize the anatomic distribution of the disease. Two radiologists independently reviewed these scans and compared it to the proposed map of sclerotomes. We found that the disease distribution conformed to the distribution of a single sclerotome in only 5 patients (17%). In another 12 patients, the lesions spanned parts of contiguous sclerotomes but did not involve the entire extent of the sclerotomes. Our findings raise concerns about the sclerotomal hypothesis being the definitive explanation for the pattern of anatomic distribution in MEL. We believe that the disease distribution can be explained by clonal proliferation of a mutated skeletal progenitor cell along the limb axis. Studies in mice models on clonal proliferation in limb buds mimic the patterns seen in melorheostosis. We also support this hypothesis by the dorso-ventral confinement of melorheostotic lesion in a patient with low allele frequency of MAP2K1-positive osteoblasts and low skeletal burden of the disease. This suggests that the mutation occurred after the formation of dorso-ventral plane. Further studies on limb development are needed to better understand the etiology, pathophysiology and pattern of disease distribution in all patients with MEL.

Trend Toward High-Volume Hospitals and the Influence on Complications in Knee and Hip Arthroplasty.

BACKGROUND: Hospitals in which a high volume of arthroplasty procedures are performed have been observed to have better outcomes. As the number of arthroplasties has increased, it is not known whether surgical cases have shifted to high-volume hospitals. In this study, we examined the change in the volume of arthroplasties to provide a contemporary definition of "high-volume" centers, quantified surgical volume that shifted to high-volume centers, and investigated the resulting effect on complications. METHODS: Data from the National (Nationwide) Inpatient Sample (2000 to 2012) were used to quantify trends in total hip arthroplasty (THA) and total knee arthroplasty (TKA) volume. Elective primary THAs and TKAs were identified and grouped by hospital by utilizing the hospital identifier, which indicates the geographic location of the hospital. County geographic and population data were obtained from the U.S. Census, and the distances between hospitals and the centroids of counties were calculated. Risk-standardized surgical complication rates for hospitals (2009 to 2012) were obtained from Medicare Hospital Compare and grouped by hospital volume. RESULTS: From 2000 to 2012, there was a marked increase in the number of hospitals that performed a combined volume of ≥400 elective primary THAs and TKAs. The number of elective primary TKAs and THAs performed annually increased from 343,000 to 851,000. In 2012, 65.5% of the arthroplasties were performed in high-volume hospitals (≥400 arthroplasties annually), and 26.6% of the arthroplasties were performed in very high-volume hospitals (≥1,000 procedures annually). The proportion of arthroplasties performed in low-volume hospitals (<100 arthroplasties annually) shrank from 17.9% to 5.4%. Very high-volume hospitals had the lowest complication rates (2.745 per 100; 95% confidence interval [CI], 2.56 to 2.93), and low-volume hospitals had the highest complication rates (3.610 per 100; 95% CI, 3.58 to 3.64; p < 0.0001) (odds ratio, 1.327; 95% CI, 1.26 to 1.40). Our analysis showed that 81.9% of the U.S. population lived within 50 miles of a high-volume hospital. CONCLUSIONS: Arthroplasty patients are electing to have their procedures at higher-volume hospitals in the United States. Each successively higher hospital volume category manifested a lower complication rate.

Scoring the SF-36 in Orthopaedics: A Brief Guide.

The Short Form-36 (SF-36) is the most widely used health-related quality-of-life measure in research to date. There are currently two sources for the SF-36 and scoring instructions: licensing them from Optum, Inc., or obtaining them from publicly available documentation from the RAND Corporation. The SF-36 yields eight scale scores and two summary scores. The physical component summary (PCS) and mental component summary (MCS) scores were derived using an orthogonal-factor analytic model that forced the PCS and MCS to be uncorrelated, and it has been shown to contribute to an inflation of the MCS in patients with substantial physical disability. Oblique scoring can reduce this inflation of the MCS in orthopaedic studies. Spreadsheets to score the SF-36, along with a copy of the questionnaire, are provided.

Trends in Media Reports, Oral Bisphosphonate Prescriptions, and Hip Fractures 1996-2012: An Ecological Analysis.

Bisphosphonates are effective for the treatment of osteoporosis despite recent reports of safety concerns such as atypical femur fracture. We conducted an ecological analysis of relevant media reports, oral bisphosphonate use, and fracture outcomes in the United States. Trends in media reports and public interest of bisphosphonates were quantified using data from Google Trends. Data from the Medical Expenditure Panel Survey (MEPS) and the National Inpatient Sample (NIS) were used to estimate the trends in oral bisphosphonate use among patients aged 55 years and older and hospitalizations for intertrochanteric and subtrochanteric fractures, respectively. These trends in the prevalence of oral bisphosphonate use and the age-adjusted incidence rate of intertrochanteric and subtrochanteric fractures were examined from 1996 to 2012. A series of spikes in Internet search activity for alendronate (Fosamax) occurred between 2006 and 2010 immediately following media reports of safety concerns. Oral bisphosphonate use declined by greater than 50% between 2008 and 2012 (p < 0.001) after increasing use for more than a decade. The decline was more common in patients with lower education levels. Intertrochanteric hip fractures declined from 1996 through 2006 (p < 0.001) and continued to decline from 2008 to 2012 (p < 0.05). Subtrochanteric and diaphyseal fractures showed a steady and significant increase from 2002 to 2011 (p < 0.05). However, the incidence decreased from a peak of 30.5 per 100,000 in 2011 to 26.7 per 100,000 in 2012. The plateauing and subsequent decline in oral bisphosphonate use since 2006 coincided with reports of safety concerns of bisphosphonates, despite the fact that U.S. Food and Drug Administration (FDA) and American Society of Bone and Mineral Research (ASBMR) reports did not recommend any safety restrictions on their use. This decline in oral bisphosphonate use was followed by the decline in the incidence of subtrochanteric and diaphyseal fractures.