Evaluation of DISORDER: Retrospective Image Motion Correction for Volumetric Brain MRI in a Pediatric Setting

BACKGROUND AND PURPOSE

Head motion causes image degradation in brain MR imaging examinations, negatively impacting image quality, especially in pediatric populations. Here, we used a retrospective motion correction technique in children and assessed image quality improvement for 3D MR imaging acquisitions.

MATERIALS AND METHODS

We prospectively acquired brain MR imaging at 3T using 3D sequences, T1-weighted MPRAGE, T2-weighted TSE, and FLAIR in 32 unsedated children, including 7 with epilepsy (age range, 2-18 years). We implemented a novel motion correction technique through a modification of k-space data acquisition: Distributed and Incoherent Sample Orders for Reconstruction Deblurring by using Encoding Redundancy (DISORDER). For each participant and technique, we obtained 3 reconstructions as acquired (Aq), after DISORDER motion correction (Di), and Di with additional outlier rejection (DiOut). We analyzed 288 images quantitatively, measuring 2 objective no-reference image quality metrics: gradient entropy (GE) and MPRAGE white matter (WM) homogeneity. As a qualitative metric, we presented blinded and randomized images to 2 expert neuroradiologists who scored them for clinical readability.

RESULTS

Both image quality metrics improved after motion correction for all modalities, and improvement correlated with the amount of intrascan motion. Neuroradiologists also considered the motion corrected images as of higher quality (Wilcoxon z = -3.164 for MPRAGE; z = -2.066 for TSE; z = -2.645 for FLAIR; all P < .05).

CONCLUSIONS

Retrospective image motion correction with DISORDER increased image quality both from an objective and qualitative perspective. In 75% of sessions, at least 1 sequence was improved by this approach, indicating the benefit of this technique in unsedated children for both clinical and research environments.

Blood biomarker modulation with dasatinib (D) and cetuximab (C) in patients (pts) with advanced solid malignancies

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Background: Src is implicated in the resistance to epidermal growth factor receptor (EGFR) inhibitors. We studied biomarkers in the context of a phase I clinical trial of D, a small molecule inhibitor of several kinases, including Src, and C, a chimeric IgG1 monoclonal anti-EGFR antibody (Esteve et al. ASCO 2008; A14668). Methods: Plasma levels of EGFR, amphiregulin (AR), transforming growth factor-α (TGF-α), COX-2 and hepatocyte growth factor (HGF) were measured using a multiplex enzyme-linked immunosorbant assay (Searchlight TM) at day 0 and day 15. Blood mononuclear cell pSrc/Src levels were measured by Odyssey western blotting at day 0 (no C) and day 15 (with C) prior to and 2, 4, 8 and 24 hours after D. Clinical results were tested for association with biomarkers. The same biomarkers were also measured in plasma collected through an Early Detection Research Network- (EDRN-) sponsored effort from 22 squamous cell carcinoma of the head and neck (SCCHN) pts and 32 cancer-free matched controls. Results: 25 pts had baseline levels, 16 with paired samples. At day 15, EGFR plasma levels significantly decreased (p < 0.001), while AR (p < 0.001) and TGF-α (p < 0.001) significantly increased compared to pretreatment levels. HGF and COX 2 plasma levels did not change with treatment. Pre-daily D pSrc levels on day 0 and day 15 did not differ. pSrc levels decreased from pre-daily D levels by 8 hours post-D at day 0 (p = 0.036, n = 21) and day 15 (p = 0.027, n = 13) and returned to pre-D levels by 24 hours. In 17 pts evaluable for response, only low baseline levels of TGF-α were associated with an increased likelihood of disease control (p = 0.020). Elevated HGF at baseline was seen in treatment pts and SCCHN control pts compared to cancer-free controls (p = 0.006 and p = 0.001, respectively). Otherwise, there was no significant difference in plasma biomarker levels compared to the matched EDRN. Conclusions: D and C significantly decreased plasma levels of EGFR and increased EGFR ligands (AR and TGF-α). Similar data has been shown in vitro, suggesting that C binding to EGFR leads to fewer available receptors for ligand binding. pSrc transiently decreased after D dosing. We will evaluate C plus D and validate these biomarkers in a planned phase II trial in SCCHN.

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