Table of Contents
Perspectives
Review Article
Health Care Reform Vignette
Practice Perspectives
General Contents
Commentary
- Early Biomarkers from Conventional and Delayed-Contrast MRI to Predict the Response to Bevacizumab in Recurrent High-Grade Gliomas
Twenty-four patients with recurrent high-grade gliomas were scanned before and during bevacizumab treatment with standard and delayed-contrast MRI. The mean change in lesion volumes of responders (overall survival, >1 year) and nonresponders (overall survival, <1 year) was evaluated. Treatment-response-assessment maps (TRAMs) were calculated by subtracting conventional T1WI (acquired a few minutes postcontrast) from delayed T1WI (acquired with a delay of >1 hour postcontrast). These maps depict the spatial distribution of contrast accumulation and clearance. At progression, the increase in lesion volumes in delayed-contrast MR imaging was 37.5% higher than the increase in conventional T1WI. The authors conclude that the benefit of standard and delayed-contrast MRI for assessing and predicting the response to bevacizumab was demonstrated and that the increased sensitivity of delayed-contrast MRI reflects its potential contribution to the management of bevacizumab-treated patients with recurrent HGG.
- Comparison of CTA- and DSA-Based Collateral Flow Assessment in Patients with Anterior Circulation Stroke
The authors set out to determine the agreement between collateral flow assessment on CTA and DSA and their respective associations with clinical outcome. They used patient data that was randomized in MR CLEAN with middle cerebral artery occlusion and both baseline CTA images and complete DSA runs. Collateral flow on CTA and DSA was graded 0 (absent) to 3 (good).Of 45 patients with evaluable imaging data, collateral flow was graded on CTA as 0, 1, 2, 3 for 3, 10, 20, and 12 patients, respectively, and on DSA for 12, 17, 10, and 6 patients, respectively. The adjusted odds ratio for favorable outcome on mRS was 2.27 and 1.29 for CTA and DSA, respectively. The relationship between the dichotomized collateral score and mRS 0–2 was significant for CTA, but not for DSA. They conclude that the commonly applied collateral flow assessment on CTA and DSA showed large differences and that these techniques are not interchangeable. CTA was significantly associated with mRS at 90 days, whereas DSA was not.
- Mechanical Thrombectomy in Patients with Acute Ischemic Stroke and Lower NIHSS Scores: Recanalization Rates, Periprocedural Complications, and Clinical Outcome
This is a retrospective analysis of 484 patients in a prospectively collected stroke data base. The inclusion criteria were anterior circulation ischemic stroke treated with mechanical thrombectomy at a single institution between September 2010 and October 2015 with an NIHSS score of ≤8. The purpose was to assess the clinical and interventional data in patients treated with mechanical thrombectomy in case of ischemic stroke with mild-to-moderate symptoms (n = 33). Recanalization (TICI 2b–3) was achieved in 26 (78.7%) patients. Two cases of symptomatic intracranial hemorrhage occurred. Favorable (mRS 0–2) and moderate (mRS 0–3) clinical 90-day outcome was achieved in 63.6% and 90.9% of patients, respectively. The authors conclude that the clinical outcome of patients undergoing mechanical thrombectomy for acute ischemic mild stroke due to large-vessel occlusion is predominately favorable, even in a prolonged time window.
- Vitamin D and Vulnerable Carotid Plaque
Angiotensin II stimulates intraplaque hemorrhage in animal models, and the angiotensin system is highly regulated by vitamin D. The authors' purpose was to determine whether low vitamin D levels predict carotid intraplaque hemorrhage (IPH). In this cross-sectional study, 65 patients with carotid disease underwent carotid MR imaging and blood draw. Systemic clinical confounders and local lumen imaging markers were recorded. They performed multivariable Poisson regression by using generalized estimating equations to account for up to 2 carotid arteries per patient and backward elimination of confounders. The authors found that low vitamin D levels (<30 ng/mL) were a significant predictor of MRI-detected IPH, along with plaque thickness. They conclude that vitamin D insufficiency was associated with both the presence and volume of carotid IPH in patients with carotid atherosclerosis and that these results link low vitamin D levels with plaque vulnerability.
- Imaging Features of Malignant Lacrimal Sac and Nasolacrimal Duct Tumors
This case series presents 18 patients with primary and secondary malignant lacrimal sac and nasolacrimal duct tumors and their pattern of tumor spread. Squamous cell carcinoma was the most common histology and, in 15/18 patients tumor involved both the lacrimal sac and duct at the time of diagnosis. In 11/16 patients on CT, the nasolacrimal bony canal was smoothly expanded without erosive changes. Tumor was not observed solely within the nasolacrimal duct in any patient. Only 1 patient presented with nodal metastasis and there was no intracranial tumor extension or perineural tumor spread. The authors conclude that malignant lacrimal sac and nasolacrimal duct tumors tend to expand the nasolacrimal bony canal, rather than erode it. CT was superior to MR imaging in characterizing expansion versus erosion of the nasolacrimal bony canal.
- Cervical Spinal Cord DTI Is Improved by Reduced FOV with Specific Balance between the Number of Diffusion Gradient Directions and Averages
The authors evaluated multiple parameters of reduced-FOV DTI to optimize image quality. Fifteen healthy individuals underwent cervical spinal cord 3T MRI, including an anatomic 3D Multi-Echo Recombined Gradient Echo, high-resolution full-FOV DTI with a NEX of 3 and 20 diffusion gradient directions, and 5 sets of reduced-FOV DTIs differently balanced in terms of NEX/number of diffusion gradient directions. Qualitatively, reduced-FOV DTI sequences with a NEX of >5 were significantly better rated than the full-FOV DTI and the reduced-FOV DTI with low NEX (N=3) and a high number of diffusion gradient directions (D=20). Quantitatively, the best trade-off was reached by the reduced-FOV DTI with a NEX of 9 and 9 diffusion gradient directions. They conclude that the best compromise was obtained with a NEX of 9 and 9 diffusion gradient directions, which emphasizes the need for increasing the NEX at the expense of the number of diffusion gradient directions for spinal cord DTI, unlike brain imaging.
