Magnetisation transfer parameters and stroke outcome.

Our aim was to evaluate the association between magnetisation transfer imaging (MTI) parameters measured 30 to 45 days after a cerebrovascular insult and post-stroke functional outcome at the same time. MTI offers the opportunity to depict subtle microstructural changes in infarcted areas. The clinical significance of the heterogeneity of brain damage within ischaemic stroke lesions is unknown. We prospectively included 58 patients with acute middle cerebral artery stroke. Diffusion-weighted imaging was performed within 12 hours after onset and the final infarct was documented by MRI with fluid-attenuated inversion recovery (FLAIR) and MTI at 30 to 45 days follow-up. We evaluated the association between MTI histogram parameters and the clinical outcome assessed by dichotomised (threshold >2) modified rankin scale (mRS) using multivariable logistic regression models adjusted on baseline characteristics. In multivariable analyses, stroke outcome was mostly driven by initial National Institutes of Health Stroke Scale (odds ratio [OR]=1.23; 95% confidence interval [CI]=1.07-1.41; p<0.01) while after adjustment of initial stroke severity magnetisation transfer ratio peak position was the only MRI parameter associated with functional status at 30 to 45 days post-stroke (OR=0.86; 95% CI=0.75-0.98; p=0.02); lower peak position values associated with higher mRS. Conversely, stroke volume measured on FLAIR sequence was not associated with stroke prognosis (p=0.87). The intensity of microstructural changes within the infarct core measured at 30 to 45 days follow-up is independently associated with the functional status evaluated at the same time. MTI and related parameters could be used as surrogate markers of treatment response in stroke clinical trials.

Whole-body MRI with diffusion-weighted sequences compared with 18 FDG PET-CT, CT and superficial lymph node ultrasonography in the staging of advanced cutaneous melanoma: a prospective study.

OBJECTIVES: The aim of our study was to compare the diagnostic performances of non-radiating whole-body magnetic resonance imaging (wbMRI), either volumetric, with Volumetric interpolated breath-hold examination (VIBE) or metabolic, with diffusion-weighted sequences (wbMRI), with classical irradiating techniques such as PET-CT, CT and with lymph node ultrasonography (US) for the staging of advanced melanoma. PATIENTS AND METHODS: Thirty-seven melanoma AJCC stage IV patients were prospectively included. All images were independently interpreted without prior knowledge of the results of studies performed with concurrent techniques, and all imaging techniques were scheduled within a mean interval of 7 days. The overall and site-specific diagnosis performances of each imaging modality were studied, as well as the interest of combined MRI VIBE and diffusion sequences. RESULTS: The number of visceral or lymph node metastases spotted was, respectively, 218, with 125 metastases for wbMRI, 191/103 for PET-CT, 209/115 for CT and 33/13 for lymph node US. No statistically significant difference (P < 0.05) of overall diagnostic performances between wbMRI (Se 84%, Sp 87.1%, PPV 89.8%, NPV 80.2%) and PET-CT (Se 79.8%, Sp 93.1%, PPV 93.2%, NPV 79.4%) was observed. No statistically significant difference was found between wbMRI and PET-CT with two channels for CT with respect to different metastatic sites. Compared with the CT, wbMRI had significantly better overall specificity (P = 0.0011) and PPV (P = 0.02). For lung exploration, sensitivity of wbMRI (51.6%) was inferior to CT (71.4%). To detect superficial metastatic lymph nodes, wbMRI and US both showed high diagnostic accuracy with no statistically significant difference. Intra-observer agreement was almost perfect for all imaging modalities considering the overall staging. Inter-observer agreement for wbMRI and diffusion alone was almost perfect except for bone and lymphatic sites. Overall diagnostic performance of diffusion alone was significantly inferior to those of combined VIBE and diffusion sequences. CONCLUSIONS: Whole-body MRI, using diffusion weighted sequences, was a reliable non-radiating imaging for staging of melanoma and offers the same diagnostic performances than combined CT, PET-CT and lymph node US.

Results of the PERFORM magnetic resonance imaging study.

The PERFORM MRI Project was an ancillary study of the PERFORM trial. Its aim was to investigate the potential effects of terutroban in patients with atherothrombotic disorders, in comparison to aspirin, on the evolution of magnetic resonance imaging (MRI) lesions after a recent ischemic stroke or transient ischemic attack (TIA). The change in both hypointense and hyperintense lesions on the fluid attenuated inversion recovery (FLAIR) sequence, in the total brain volume and in the hippocampal volume from baseline (M1) to the final visit (M24) was assessed as well as the number of emergent microbleeds. A total of 748 patients had their MRI examination validated both at M1 and M24 during the study. At baseline, the volume of hypointense and hyperintense lesions on FLAIR images, the total brain volume, the hippocampal volume and the number of patients with microbleeds did not differ between the two groups. During follow-up, the mean volumetric increase of lesions hypointense or hyperintense on FLAIR images (from 5 to 8 %), the mean reduction of total brain volume (−0.4 %) and of hippocampal volume (−4 %), did not differ between the two treatment arms. The same parameters analysed ipsilateral to the ischaemic lesion did not differ either between the two groups. In the terutroban group, 16.3 % of patients presented with emergent microbleeds, 10.7 % in the aspirin group; this difference was not significant. In the PERFORM study, the progression of FLAIR lesions, of cerebral or hippocampal atrophy and of microbleeds did not differ between patients treated by terutroban and those treated by aspirin.

Final cerebral infarct volume is predictable by MR imaging at 1 week.

BACKGROUND AND PURPOSE: Stroke volume, an increasingly used end point in phase II trials, is considered stationary at least 30 days after the ictus. We investigated whether information conveyed by MR imaging measurements of the "final" infarct volume could be assessed as early as the subacute stage (days 3-6), rather than waiting for the chronic stage (days 30-45). MATERIALS AND METHODS: Ninety-five patients with middle cerebral artery stroke prospectively included in a multicenter study underwent MR imaging during the first 12 hours (MR imaging-1), between days 3 and 6 (MR imaging-2), and between days 30 and 45 (MR imaging-3). We first investigated the relationship between subacute (FLAIR-2) and chronic volumes (FLAIR-3), by using a linear regression model. We then tested the relationship between FLAIR volumes (either FLAIR-2 or FLAIR-3) and functional disability, measured by the mRS at the time of MR imaging-3, by using logistic regression. The performances of the models were assessed by using the AUC in ROC. RESULTS: A linear association between log FLAIR-2 and log FLAIR-3 volumes was observed. The proportion of FLAIR-3 variation, explained by FLAIR-2, was high (R(2) = 81%), without a covariate that improved this percentage. Both FLAIR-2 and FLAIR-3 were independent predictors of mRS (OR, 0.79 and 0.73; 95% CI, 0.64-0.97 and 0.56-0.96; P = .026 and .023). The performances of the models for the association between either FLAIR volume and mRS did not differ (AUC = 0.897 for FLAIR-2 and 0.888 for FLAIR-3). CONCLUSIONS: Stroke damage may be assessed by a subacute volume because subacute volume predicts the "true" final volume and provides the same clinical prognosis.

Design, data management, and population baseline characteristics of the PERFORM magnetic resonance imaging project.

Quantitative information from magnetic resonance imaging (MRI) may substantiate clinical findings and provide additional insight into the mechanism of clinical interventions in therapeutic stroke trials. The PERFORM study is exploring the efficacy of terutroban versus aspirin for secondary prevention in patients with a history of ischemic stroke. We report on the design of an exploratory longitudinal MRI follow-up study that was performed in a subgroup of the PERFORM trial. An international multi-centre longitudinal follow-up MRI study was designed for different MR systems employing safety and efficacy readouts: new T2 lesions, new DWI lesions, whole brain volume change, hippocampal volume change, changes in tissue microstructure as depicted by mean diffusivity and fractional anisotropy, vessel patency on MR angiography, and the presence of and development of new microbleeds. A total of 1,056 patients (men and women ≥ 55 years) were included. The data analysis included 3D reformation, image registration of different contrasts, tissue segmentation, and automated lesion detection. This large international multi-centre study demonstrates how new MRI readouts can be used to provide key information on the evolution of cerebral tissue lesions and within the macrovasculature after atherothrombotic stroke in a large sample of patients.