Variation in use of head computed tomography by emergency physicians

ObjectiveVariation in emergency department head computed tomography (CT) use in patients with atraumatic headaches between hospitals is being measured nationwide. However, the magnitude of interphysician variation within a hospital is currently unknown. We hypothesized that there was significant variation in the rates of physician head CT use, both overall and for patients diagnosed with atraumatic headaches.MethodsThis cross-sectional study was conducted in the emergency department of a large urban academic hospital, and institutional review board approval was obtained. All emergency department visits from 2009 were analyzed, and the primary outcome measure was whether or not head CT was performed. Logistic regression was used to control for patient, physician, and visit characteristics potentially associated with head CT ordering. The degree of interphysician variability was tested, both before and after controlling for these variables.ResultsOf 55,286 emergency department patient encounters, 4919 (8.9%) involved head CT examinations. Unadjusted head CT ordering rates per physician ranged from 4.4% to 16.9% overall and from 15.2% to 61.7% in patients diagnosed with atraumatic headaches, with both rates varying significantly between physicians. Two-fold variation in head CT ordering overall (6.5%-13.5%) and approximately 3-fold variation in head CT ordering for atraumatic headaches (21.2%-60.1%) persisted even after controlling for pertinent variables.ConclusionEmergency physicians vary significantly in their use of head CT both overall and in patients with atraumatic headaches. Further studies are needed to identify strategies to reduce interphysician variation in head CT use.     

Assessing neurotoxicity from the low-dose radiation component of radiosurgery using magnetic resonance spectroscopy

The aim of the study was to determine if biochemical changes indicative of injury, assessed using magnetic resonance spectroscopic imaging (SI), are observed after stereotactic radiosurgery (SRS). The study included patients who underwent SI immediately before and 1, 30, and 90 days following SRS. Short TE spectra (TR/TE 1000/35 ms) were acquired at the SRS isocenter with a 2D PRESS-CSI sequence on a single 1.5 T scanner. The SRS isodose lines were overlaid on the magnetic resonance imaging slice utilized for SI data acquisition. N-Acetyl aspartate (NAA)/creatine (Cr) and choline (Cho)/Cr ratios were computed for multiple voxels located between the 25 and 50 cGy isodose lines (low dose) and the 200 and 350 cGy isodose lines (medium dose). An analysis of variance and paired t-tests compared metabolite levels at different time points. Twelve patients were enrolled, although 3 were excluded secondary to poor spectral data quality or deviations from the prescribed SI protocol. The median number of voxels analyzed from the low- and medium-dose region was 7 and 4, respectively. No significant changes in metabolite peak height ratios over time were seen in the low-dose region, for either NAA/Cr (P = .89) or Cho/Cr (P = .85). There was no difference in Cho/Cr peak height ratios in the medium-dose region (P = .62). There was an increase in the NAA/Cr peak height ratio in the medium-dose region between day −1 and day +30 (P = .003), followed by a decline to baseline between days +30 and +90 (P = .03). We did not observe a significant decline in NAA/Cr or change in Cho/Cr peak heights in uninvolved brain parenchyma after SRS.