Resting-State BOLD MRI for Perfusion and Ischemia.

Advanced imaging techniques including computed tomography (CT) angiography, CT perfusion, magnetic resonance (MR) angiography, MR with diffusion- and perfusion-weighted imaging, and, more recently, resting-state BOLD (Blood Oxygen Level Dependent) functional MRI (rs-fMRI) are increasingly used to evaluate patients with acute ischemic stroke. Advanced imaging allows for identification of patients with ischemic stroke and determination of the size of infarcted and potentially salvageable tissue, all of which yield crucial information for proper stroke management. The addition of rs-fMRI for ischemia adds information at the microvascular level, thereby improving the understanding of pathophysiologic mechanisms of impaired cerebral perfusion and tissue oxygenation beyond the known concepts at the macrovascular level. As such, it may further delineate functional and dysfunctional neuronal networks, guide stroke interventions, and improve prognosis and monitoring of patient outcomes.

Trends in lumbar puncture over 2 decades: a dramatic shift to radiology.

OBJECTIVE: The purpose of this study is to evaluate national trends in lumbar puncture (LP) procedures and the relative roles of specialty groups providing this service. MATERIALS AND METHODS: Aggregated claims data for LPs were extracted from Medicare Physician Supplier Procedure Summary master files annually from 1991 through 2011. LP procedure volumes by specialty group and place of service were studied. RESULTS: Between 1991 and 2011, the overall numbers of LP procedures increased, with a slight increase in diagnostic LP procedures (90,460 vs 90,785) and a marked increase in therapeutic LP procedures (2868 vs 6461) in Medicare fee-for-service beneficiaries. Although radiologists performed 11.3% (n = 10,533) of all LP procedures in 1991, they performed 46.6% (n = 45,338) in 2011. For diagnostic LPs, radiology (11.4% [n = 10,272] in 1991 and 48.0% [n = 43,601] in 2011) now exceeds emergency medicine, neurosciences, and all others as the dominant provider group. For therapeutic LP procedures, radiology now performs the second greatest number of LP procedures (9.0% [n = 261] in 1991 and 26.9% [n = 1737] in 2011). Although volumes remain small (< 10% of all procedures), midlevel practitioners have experienced over 100-fold growth for most services. The inpatient hospital setting remains the dominant site of service (71,385 in 1991 vs 44,817 in 2011: -37%), followed by procedures performed in the emergency department (297 in 1991 vs 26,117 in 2011: 8794%). CONCLUSION: Over the last 2 decades, LP procedures on Medicare beneficiaries have increased, with radiology now the dominant overall provider. Although this trend may have relatively negative financial implications for radiology practices in current fee-for-service payment models, it has the potential to cement radiology's more central position through direct involvement in patient care in emerging accountable care organizations.

Biphasic blood pool contrast agent-enhanced whole-body MR angiography for treatment planning in patients with significant arterial stenosis.

OBJECTIVE: To prospectively evaluate diagnostic accuracy of first pass and combined first pass and steady state high-spatial-resolution whole-body magnetic resonance (MR) angiography with a blood pool contrast agent for quantification of arterial stenosis in different vascular territories. MATERIALS AND METHODS: After Institutional Review Board approval and informed consent, 50 patients with known 50% or greater stenosis in at least one vascular territory; as shown by the standard-of-reference (14 digital subtraction angiographies, 4 computed tomographies, 32 ultrasound examinations), were included. The patients underwent MR angiography at 1.5 Tesla, using a standardized nonbody-weight-adapted i.v. bolus injection of 11 mL gadofosveset trisodium. First pass imaging with 4 different table positions in a whole-body MR scanner (MAGNETOM Avanto, Siemens Healthcare), using individual circulation time determined by a test bolus, was performed. Steady state imaging was performed using an isometric spatial resolution of 1.0 mm. Image quality was rated. Each vascular segment in MR angiography was evaluated by 2 independent and blinded reviewers and the stenosis degree was compared with the preferred standard-of-reference, using a 5-point scale. Differences between first pass and combined MR angiography were assessed with a 95% confidence interval (CI) by applying the adjusted modified chi(2) test. Changes in therapy based on the whole-body examination strategy were evaluated. RESULTS: The number of nondiagnostic territories was 24 of 197 (12.2%) for first pass MR angiography and decreased to 3 of 197 (1.5%) after addition of steady state MR angiography. The diagnostic accuracy for quantification of arterial stenosis in combined MR angiography (94.7%; 95% CI: 92.4-97.1) was superior to first pass MR angiography (81.7%; 95% CI: 73.7-89.8; statistically significant). Patient management was changed in 12 of 49 patients, in 7 of 12 patients the change was applied to an additional lesion detected by the whole-body examination strategy. CONCLUSION: The quantification and detection of arterial stenosis is improved by the steady state high-resolution gadofosveset trisodium-enhanced MR angiography. Additional lesions detected by whole-body examination strategy or differences in stenosis quantification may lead to changes in therapy.

First-pass whole-body magnetic resonance angiography (MRA) using the blood-pool contrast medium gadofosveset trisodium: comparison to gadopentetate dimeglumine.

OBJECTIVES: To evaluate gadofosveset trisodium for first-pass magnetic resonance angiography (MRA) in the setting of whole-body MRA (WB-MRA). MATERIALS AND METHODS: Forty patients were examined using either 10 mL gadofosveset trisodium (n = 20) or 30 mL gadopentetate dimeglumine (n = 20), followed by arterial-phase imaging of 4 consecutive anatomic regions. Signal intensity was measured in 2 vessels per region. Relative contrast values (RC) were calculated. Arterial contrast, venous overlay, and image quality were rated by 2 radiologists. The Mann-Whitney U test was used to test for significance. RESULTS: Compared with gadopentetate dimeglumine, gadofosveset trisodium enhanced imaging revealed higher RC values in 2 vessel regions, with the differences being significant in 3 of 4 vessel segments. Gadofosveset trisodium revealed lower RC values in 2 regions with significant differences in 2 segments. Qualitative evaluation revealed higher ratings for gadofosveset trisodium regarding all 3 criteria with significant differences in 2 regions. CONCLUSIONS: Gadofosveset trisodium serves well for first-pass imaging in WB-MRA.