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Objective: Although most musculoskeletal MRI examinations are interpreted by radiologists, some nonradiologists provide interpretations as well. We aimed to study day of week (weekday vs weekend), site of service, and patient complexity differences between radiologists and nonradiologists interpreting lower extremity MRI examinations on Medicare beneficiaries., Materials and Methods: Using fee-for-service carrier claims for a 5% sample of Medicare beneficiaries nationally from 2012 through 2014, we identified all lower extremity joint MRI examinations. Services were classified by physician specialty, day of week, and site of service. Charlson comorbidity index (CCI) values were calculated for all patients. Chi-square statistical testing was performed., Results: Of all 125,800 billed lower extremity joint MRI examinations, 118,295 (94.0%) were performed on weekdays and 7505 (6.0%) on weekends. Of the weekday examinations, radiologists interpreted 85,991 (83.3%) and nonradiologists 17,260 (16.7%). Of the weekend examinations, radiologists interpreted 6212 (92.8%) and nonradiologists 485 (7.2%). Of examinations performed in inpatient hospital and emergency department settings, radiologists interpreted 6499 (99.2%) and nonradiologists 51 (0.8%). Of the examinations on the most clinically complex patients (CCI ≥ 3), radiologists interpreted 4228 (90.2%) and nonradiologists 461 (9.8%). All interspecialty differences were statistically significant (p < 0.001)., Conclusion: In the Medicare population, radiologists interpret most lower extremity joint MRI examinations. Compared with nonradiologists, radiologists disproportionately provide services on weekends, in the highest acuity settings, and on the most clinically complex patients. To promote patient access and minimize disparities, future pay-for-performance metrics should consider temporal, acuity, and complexity parameters.

Objective: Endovascular stenting is a safe, effective treatment of hepatic artery stenosis after liver transplant, but no detailed evaluation has been completed of changes in ultrasound monitoring parameters after stenting. This study aims to improve poststenting surveillance by delineating the expected postoperative findings., Materials and Methods: Thirty-one stent procedures were performed at our institution for hepatic artery stenosis after liver transplant between October 2010 and October 2012. Of these, 28 (90%) were technically successful, of which 23 met the minimum follow-up time (76 days, defined by the earliest diagnosed restenosis). These patients were followed with serial ultrasound, per the following schedule: within 1 week of stenting, 3 months after stenting, 6 months after stenting, and every 6 months thereafter; additional, unscheduled examinations were frequently performed when indicated on the basis of deterioration of clinical and laboratory status. Follow-up examinations (mean, 268 days total follow-up) were compared with prestenting examinations to evaluate changes in peak systolic velocity (PSV), resistive index (RI), and tardus-parvus waveforms. Data were analyzed to determine a normal range for postprocedure values and time course of change in values., Results: Of the 23 patients, six experienced restenosis. In all patients, mean PSV decreased by 124 cm/s, and mean RI increased by 0.13 within 48 hours after stenting. PSV differed between patency and restenosis groups only at more than 90 days after stenting (mean PSV, 234 and 400 cm/s, respectively), with PSV above 300 cm/s serving as a high-sensitivity threshold for the determination of restenosis. Prestenting RI of below 0.40 had a strong correlation with restenosis. Poststenting RI differed between patency and restenosis groups only at more than 48 hours after stenting, with RI of below 0.55 having a strong correlation with restenosis. Tardus-parvus waveform resolution was often delayed well beyond 48 hours after stenting, and time to tardus-parvus waveform resolution had no correlation with patency or restenosis., Conclusion: Ultrasound is convenient and useful to follow stents in hepatic artery stenosis after liver transplant. Prestenting hemodynamics can have value in predicting restenosis. Diagnosis of restenosis can be made with RI and PSV, whereas resolution time of tardus-parvus waveform is of less concern. These parameters can guide which patients require closer monitoring and aggressive treatment.