Table of Contents
Perspectives
General Contents
- Multimodal CT Imaging: Time to Treatment and Outcomes in the IMS III Trial
The authors explored the effect of multimodal imaging (CT perfusion and/or CT angiography) versus noncontrast CT alone on time to treatment and outcomes in the IMS III trial. Of 656 subjects enrolled in the trial, 90 (13.7%) received CTP and CTA, 216 (32.9%) received CTA (without CTP), and 342 (52.1%) received NCCT alone. Median times from stroke onset to IV tPA in the CTP+CTA, CTA, and NCCT groups were 120.5 vs 117.5 vs 120 minutes, respectively. They conclude that the use of CTA (with or without CTP) did not delay IV tPA or endovascular therapy compared with NCCT in the IMS III trial.
- T1 Signal-Intensity Increase in the Dentate Nucleus after Multiple Exposures to Gadodiamide: Intraindividual Comparison between 2 Commonly Used Sequences
The authors performed intraindividual qualitative and quantitative comparison between T1-weighted spin-echo and 3D MPRAGE images in 18 patients who had multiple exposures to gadodiamide. Differences in signal between the 2 sequences for both baseline and last examination dentate nucleus/middle cerebellar peduncle ratios were statistically significant. They conclude that T1-weighted spin-echo and MPRAGE sequences cannot be used interchangeably for qualitative or quantitative signal intensity analysis of the dentate nucleus in patients who received gadodiamide.
- Improved Leakage Correction for Single-Echo Dynamic Susceptibility Contrast Perfusion MRI Estimates of Relative Cerebral Blood Volume in High-Grade Gliomas by Accounting for Bidirectional Contrast Agent Exchange
The authors' hypothesis is that incorporating bidirectional contrast agent transport into the DSC MR imaging signal model will improve rCBV estimates in brain tumors. A unidirectional contrast agent extravasation model (Boxerman-Weisskoff) was compared with a bidirectional contrast agent exchange model. For both models, they compared the goodness of fit with the parent leakage-contaminated relaxation rate curves and the difference between modeled interstitial relaxation rate curves and dynamic contrast-enhanced MR imaging in 21 patients with glioblastoma. The authors conclude that the bidirectional model more accurately corrects for the T1 or T2* enhancement arising from contrast agent extravasation due to blood-brain barrier disruption in high-grade gliomas by incorporating interstitial washout rates into the DSC MR imaging relaxation rate model.
- Cortical Perfusion Alteration in Normal-Appearing Gray Matter Is Most Sensitive to Disease Progression in Relapsing-Remitting Multiple Sclerosis
Bookend perfusion was used to quantify parameters in normal-appearing and lesional tissue at different relapsing-remitting MS stages in 39 patients and 19 age-matched healthy controls. Perfusion parameters such as CBF, CBV, and MTT were compared along with cognitive performance. White matter lesion but not cortical lesion perfusion was significantly reduced in cognitively impaired patients with relapsing-remitting MS versus unimpaired patients with relapsing-remitting MS. Perfusion reduction with disease progression was greater in normal-appearing gray matter and normal-appearing white matter compared with cortical lesions and white matter lesions. The authors conclude that the greatest changes are present within NAGM and NAWM, necessitating absolute rather than relative lesion perfusion measurement.
- Electrophysiologic Validation of Diffusion Tensor Imaging Tractography during Deep Brain Stimulation Surgery
Eleven patients underwent subthalamic nucleus deep brain stimulation. DTI and high-resolution T1- and T2-weighted MRI were performed at 3T. The electrode positions and current amplitudes that elicited corticospinal tract effects during the operation were studied to determine relative corticospinal tract distance. The mean intraoperative electrophysiologic corticospinal tract distance was 3.0 mm +/- 0.6 mm; the mean image-derived corticospinal tract distance (DTI fiber tractography) was 3.0 mm +/- 1.3 mm. DTI fiber tractography depicted the medial corticospinal border in concordance with electrophysiology under 2 different conditions and modeling approaches. Under both conditions, the electrophysiologic measurements were clearly related to the DTI fiber tractography.
- Evaluation of Focal Cervical Spinal Cord Lesions in Multiple Sclerosis: Comparison of White Matter–Suppressed T1 Inversion Recovery Sequence versus Conventional STIR and Proton Density–Weighted Turbo Spin-Echo Sequences
The authors performed a retrospective blinded analysis of cervical cord MR imaging examinations of 50 patients with MS. In each patient, 2 neuroradiologists measured the number of focal lesions and overall lesion conspicuity in the STIR/proton density–weighted TSE and WM-suppressed T1 inversion recovery sequence groups. Substantial interreader agreement was noted on the WM-suppressed T1 inversion recovery sequence compared with STIR/proton density–weighted TSE. Average lesion conspicuity was better on the WM-suppressed T1 inversion recovery sequence. Additionally, spurious lesions were more common on STIR/proton density–weighted TSE than on the WM-suppressed T1 inversion recovery sequence. They conclude that the WM-suppressed T1 inversion recovery sequence could potentially be substituted for either STIR or proton density–weighted TSE sequences in routine clinical protocols.
