Performance measures in neuroradiology

A systematic review and critical appraisal of quality measures for the emergency care of acute ischemic stroke

Acute stroke is an important focus of quality improvement efforts. There are many organizations involved in quality measurement for acute stroke, and a complex landscape of quality measures exists. Our objective is to describe and evaluate existing US quality measures for the emergency care of acute ischemic stroke patients in the emergency department (ED) setting. We performed a systematic review of the literature to identify the existing quality measures for the emergency care of acute ischemic stroke. We then convened a panel of experts to appraise how well the measures satisfy the American College of Cardiology/American Heart Association (ACC/AHA) criteria for performance measure development (strength of the underlying evidence, clinical importance, magnitude of the relationship between performance and outcome, and cost-effectiveness). We identified 7 quality measures relevant to the emergency care of acute ischemic stroke that fall into 4 main categories: brain imaging, thrombolytic administration, dysphagia screening, and mortality. Three of the 7 measures met all 4 of the ACC/AHA evaluation criteria: brain imaging within 24 hours, thrombolytic therapy within 3 hours of symptom onset, and thrombolytic therapy within 60 minutes of hospital arrival. Measures not satisfying all evaluation criteria were brain imaging report within 45 minutes, consideration for thrombolytic therapy, dysphagia screening, and mortality rate. There remains room for improvement in the development and use of measures that reflect high-quality emergency care of acute ischemic stroke patients in the United States.

Quality of extracranial carotid evaluation with 256-section CT

BACKGROUND AND PURPOSE

To date, no systematic evaluation of image quality has been performed on the 256-section multidetector CT scanner for extracranial carotid evaluations. We evaluated image quality, patient dose, and examination time and compared these parameters with a 64-section multidetector CT.

MATERIALS AND METHODS

We reviewed extracranial CTA scans obtained on a 256-detector CT scanner in 50 consecutive patients. Image quality was analyzed for artifacts and vessel contrast opacification from the aortic arch to the skull base, dose to patient, and scan time. Results were compared with a control group of 50 patients imaged on a 64-section CT scanner. A Fisher exact test was used to analyze both groups with respect to vessel contrast opacification and presence of artifacts, and a Student t test was used to assess differences in patient dose between the 2 groups.

RESULTS

Quantitative and qualitative evaluations revealed >95% acceptable vessel opacification at all levels measured on the 256-section scanner. Scan time was improved (4 seconds on 256-channel). There were fewer artifacts related to metallic streak on the 256-channel CTA study, and DLP was lower on the 256-channel CTA (113.9 versus 159.8 mGy).

CONCLUSIONS

The 256-channel CTA imaging protocol for carotid arteries yielded similar vessel contrast opacification compared with the 64-channel CTA but with fewer metallic artifacts, a modest decrease in scan time, similar image quality, and a statistically significant reduction in radiation dose of 10%.

Performance measures, efficiency, productivity

The paradox of the increased use of imaging without obvious evidence of improved health outcomes has led to calls for payment based on value rather than volume. Measurement of radiologists' performance is a key component of the measurement of value. The paradigm shift occurring in radiology and health care as a whole may seem daunting to the radiologist with the clamor for increasing accountability from payers and patients alike. However, it is through powerful tools such as performance measures in radiology and their accompanying incentive-based payment systems that practices can be improved and confidence of patients restored.

Sixty-four-section multidetector CT angiography of carotid arteries: a systematic analysis of image quality and artifacts

BACKGROUND AND PURPOSE

Sixty-four-section CT scanners have recently been introduced for vascular imaging. Before such scanners reach widespread use, scanning protocol should be optimized and image quality assessed. The goals of this study were to systematically measure image quality and determine the prevalence of various types of artifacts produced by a 64-section scanner.

MATERIALS AND METHODS

We retrospectively reviewed CT angiography (CTA) scans obtained on a 64-section CT scanner in 100 consecutive patients presenting to the emergency department during a 2-month period with a suspected acute cerebrovascular event. We evaluated scan quality by using 2 different methods: First, we quantitatively assessed arterial opacification by measuring attenuation values in 9 arterial segments from the aortic arch to the distal cervical internal carotid artery, by using a threshold of 150 HU as an indicator of good opacification. Second, we assessed image contrast between arteries and veins by measuring attenuation within venous segments and recording the number of artery-vein-segment pairs in which the attenuation difference was <or=50 HU. In addition, we recorded the prevalence of the following artifacts: metallic hardware streak, contrast material streak from slow-flowing contrast material in adjacent large veins, streak artifacts from shoulders, contrast material reflux into veins of the neck, motion artifacts, and artifacts causing misrepresentation of flow dynamics simulating arterial dissection or occlusion. These results were compared with those of a historical control group of 113 patients from our institution who were imaged with the same technical parameters on a 16-section CT scanner.

RESULTS

The quantitative assessment of arterial opacification showed that 854 of 885 analyzed arterial segments (96.5%) had good opacification (ie, attenuation values >150 HU). Image contrast between artery and vein segments was also good, with 714 of 763 analyzable segment pairs (85.6%) having >50 HU difference. Artifacts obscuring arterial evaluation included streak from contrast material in the subclavian/brachiocephalic vein (32% of patients), attenuation of the x-ray beam between the shoulders (28%), beam-hardening from metallic hardware (26%), and contrast material reflux into neck veins (16%). The most clinically relevant artifacts were flow artifacts, mimicking dissection or vascular occlusion; they were seen in 14% of patients and likely are related to the rapid data acquisition for CTA on 64-section scanners (compared with the circulation of contrast material in the cervical arteries). None of the patients in our historical control group who underwent 16-section CT had flow artifacts on their CTA studies; the incidence of the other types of artifacts in this group was similar to that in patients imaged with 64-section CT.

CONCLUSIONS

The 64-section CTA imaging protocol for carotid arteries yields high-quality studies in >95% of cases.