1 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2018.

ObjectCerebrospinal fluid (CSF) T 2 mapping can potentially be used to investigate CSF composition. A previously proposed CSF T 2–mapping method reported a T 2 difference between peripheral and ventricular CSF, and suggested that this reflected different CSF compositions. We studied the performance of this method at 7 T and evaluated the influence of partial volume and B 1 and B 0 inhomogeneity.Materials and methods T 2-preparation-based CSF T 2-mapping was performed in seven healthy volunteers at 7 and 3 T, and was compared with a single echo spin-echo sequence with various echo times. The influence of partial volume was assessed by our analyzing the longest echo times only. B 1 and B 0 maps were acquired. B 1 and B 0 dependency of the sequences was tested with a phantom.Results T 2,CSF was shorter at 7 T compared with 3 T. At 3 T, but not at 7 T, peripheral T 2,CSF was significantly shorter than ventricular T 2,CSF. Partial volume contributed to this T 2 difference, but could not fully explain it. B 1 and B 0 inhomogeneity had only a very limited effect. T 2,CSF did not depend on the voxel size, probably because of the used method to select of the regions of interest.ConclusionCSF T 2 mapping is feasible at 7 T. The shorter peripheral T 2,CSF is likely a combined effect of partial volume and CSF composition.Electronic supplementary materialThe online version of this article (doi:10.1007/s10334-017-0659-3) contains supplementary material, which is available to authorized users.

ObjectivesTo assess whether volumetric cerebrospinal fluid (CSF) MRI can be used as a surrogate for brain atrophy assessment and to evaluate how the T2 of the CSF relates to brain atrophy.MethodsTwenty-eight subjects [mean age 64 (sd 2) years] were included; T1-weighted and CSF MRI were performed. The first echo data of the CSF MRI sequence was used to obtain intracranial volume, CSF partial volume was measured voxel-wise to obtain CSF volume (VCSF) and the T2 of CSF (T2,CSF) was calculated. The correlation between VCSF / T2,CSF and brain atrophy scores [global cortical atrophy (GCA) and medial temporal lobe atrophy (MTA)] was evaluated.ResultsRelative total, peripheral subarachnoidal, and ventricular VCSF increased significantly with increased scores on the GCA and MTA (R = 0.83, 0.78 and 0.78 and R = 0.72, 0.62 and 0.86). Total, peripheral subarachnoidal, and ventricular T2 of the CSF increased significantly with higher scores on the GCA and MTA (R = 0.72, 0.70 and 0.49 and R = 0.60, 0.57 and 0.41).ConclusionA fast, fully automated CSF MRI volumetric sequence is an alternative for qualitative atrophy scales. The T2 of the CSF is related to brain atrophy and could thus be a marker of neurodegenerative disease.Key points• A 1:11 min CSF MRI volumetric sequence can evaluate brain atrophy.• CSF MRI provides accurate atrophy assessment without partial volume effects.• CSF MRI data can be processed quickly without user interaction.• The measured T2of the CSF is related to brain atrophy.Electronic supplementary materialThe online version of this article (doi:10.1007/s00330-015-3932-8) contains supplementary material, which is available to authorized users.

Nonrigid registrations of pre‐ and postradiotherapy (RT) PET/CT scans of NSCLC patients were performed with different algorithms and validated tracking internal landmarks. Dice overlap ratios (DR) of high FDG‐uptake areas in registered PET/CT scans were then calculated to study patterns of relapse. For 22 patients, pre‐ and post‐RT PET/CT scans were registered first rigidly and then nonrigidly. For three patients, two types (based on Demons or Morphons) of nonrigid registration algorithms each with four different parameter settings were applied and assessed using landmark validation. The two best performing methods were tested on all patients, who were then classified into three groups: large (Group 1), minor (Group 2) or insufficient improvement (Group 3) of registration accuracy. For Group 1 and 2, DRs between high FDG‐uptake areas in pre‐ and post‐RT PET scans were determined. Distances between corresponding landmarks on deformed pre‐RT and post‐RT scans decreased for all registration methods. Differences between Demons and Morphons methods were smaller than 1 mm. For Group 1, landmark distance decreased from 9.5 ± 2.1 mm to 3.8 ± 1.2 mm (mean ± 1 SD, p < 0.001), and for Group 3 from 13.6 ± 3.2 mm to 8.0 ± 2.2 mm (p.15em=.15em0.02). No significant change was observed for Group 2 where distances decreased from 5.6 ± 1.3 mm to 4.5 ± 1.1 mm (p.15em=.15em0.02). DRs of high FDG‐uptake areas improved significantly after nonrigid registration for most patients in Group 1. Landmark validation of nonrigid registration methods for follow‐up CT imaging in NSCLC is necessary. Nonrigid registration significantly improves matching between pre‐ and post‐RT CT scans for a subset of patients, although not in all patients. Hence, the quality of the registration needs to be assessed for each patient individually. Successful nonrigid registration increased the overlap between pre‐ and post‐RT high FDG‐uptake regions.PACS number: 87.57.Q‐, 87.57.C‐, 87.57.N‐, 87.57.‐s, 87.55.‐x, 87.55.D‐, 87.55.dh, 87.57.uk, 87.57.nj