Refine
Has Fulltext
- yes (13)
Is part of the Bibliography
- yes (13)
Document Type
- Journal article (13)
Language
- English (13) (remove)
Keywords
- MRI (3)
- data acquisition (2)
- magnetic resonance imaging (2)
- rotator cuff (2)
- shoulder surgery (2)
- 1H-Magnetic resonance spectroscopy (1H-MRS) (1)
- 3 T (1)
- Cystic fibrosis (1)
- Dixon (1)
- Exercise capacity (1)
- Extracellular volume (1)
- L-arginine (1)
- Lung disease, (1)
- MOLLI (1)
- MRI spectroscopy (1)
- Medizin (1)
- Muscle function (1)
- Muscle power (1)
- NMR relaxation (1)
- Phosphorylation (1)
- SASHA (1)
- ShMOLLI (1)
- T1 mapping (1)
- VIBE (1)
- algorithms (1)
- breath-hold (1)
- cardiac (1)
- central nervous system (1)
- cerebrospinal fluid (1)
- classification (1)
- clinical application (1)
- cold pressor test (1)
- density (1)
- echo planar imaging (1)
- endothelium (1)
- fatty degeneration (1)
- free‐breathing (1)
- functional magnetic resonance imaging (1)
- gadoxetic acid (1)
- gender (1)
- goutallier (1)
- gradient impulse response function (1)
- gradient system respose (1)
- gradient system trasfer function (1)
- imaging techniques (1)
- lung (1)
- magnetic resonance (1)
- matched filters (1)
- metabolism (1)
- myocardial perfusion (1)
- myocardium (1)
- relaxation (physics) (1)
- relaxation time (1)
- self‐gated (1)
- signal filtering (1)
- smoking (1)
- spectroscopy (1)
- standard (1)
- statistical data (1)
- temperature dependency (1)
- thermal variation (1)
- triglycerides (1)
- ultrasound (1)
- wave‐CAIPI (1)
Institute
- Institut für diagnostische und interventionelle Radiologie (Institut für Röntgendiagnostik) (12)
- Deutsches Zentrum für Herzinsuffizienz (DZHI) (3)
- Kinderklinik und Poliklinik (2)
- Klinik und Poliklinik für Strahlentherapie (2)
- Klinik und Poliklinik für Unfall-, Hand-, Plastische und Wiederherstellungschirurgie (Chirurgische Klinik II) (2)
- Medizinische Klinik und Poliklinik I (2)
- Klinik und Poliklinik für Nuklearmedizin (1)
Mapping the longitudinal relaxation time \(T_1\) has widespread applications in clinical MRI as it promises a quantitative comparison of tissue properties across subjects and scanners. Due to the long scan times of conventional methods, however, the use of quantitative MRI in clinical routine is still very limited. In this work, an acceleration of Inversion-Recovery Look-Locker (IR-LL) \(T_1\) mapping is presented. A model-based algorithm is used to iteratively enforce an exponential relaxation model to a highly undersampled radially acquired IR-LL dataset obtained after the application of a single global inversion pulse. Using the proposed technique, a \(T_1\) map of a single slice with 1.6mm in-plane resolution and 4mm slice thickness can be reconstructed from data acquired in only 6s. A time-consuming segmented IR experiment was used as gold standard for \(T_1\) mapping in this work. In the subsequent validation study, the model-based reconstruction of a single-inversion IR-LL dataset exhibited a \(T_1\) difference of less than 2.6% compared to the segmented IR-LL reference in a phantom consisting of vials with \(T_1\) values between 200ms and 3000ms. In vivo, the \(T_1\) difference was smaller than 5.5% in WM and GM of seven healthy volunteers. Additionally, the \(T_1\) values are comparable to standard literature values. Despite the high acceleration, all model-based reconstructions were of a visual quality comparable to fully sampled references. Finally, the reproducibility of the \(T_1\) mapping method was demonstrated in repeated acquisitions. In conclusion, the presented approach represents a promising way for fast and accurate \(T_1\) mapping using radial IR-LL acquisitions without the need of any segmentation.
Functional magnetic resonance imaging (fMRI) has become a powerful and influential method to non-invasively study neuronal brain activity. For this purpose, the blood oxygenation level-dependent (BOLD) effect is most widely used. T2* weighted echo planar imaging (EPI) is BOLD sensitive and the prevailing fMRI acquisition technique. Here, we present an alternative to its standard Cartesian recordings, i.e. k-space density weighted EPI, which is expected to increase the signal-to-noise ratio in fMRI data. Based on in vitro and in vivo pilot measurements, we show that fMRI by k-space density weighted EPI is feasible and that this new acquisition technique in fact boosted spatial and temporal SNR as well as the detection of local fMRI activations. Spatial resolution, spatial response function and echo time were identical for density weighted and conventional Cartesian EPI. The signal-to-noise ratio gain of density weighting can improve activation detection and has the potential to further increase the sensitivity of fMRI investigations.
Background: MRI has become the mainstay of diagnostic imaging in paediatric rheumatology for lesion detection, differential diagnosis and therapy surveillance. MR imaging of synovitis, in particular, is indispensable for early diagnosis and follow-up in arthritis patients. We used diffusion-weighted MRI (DWI) as a new imaging modality in comparison to standard MRI sequences to study bone marrow oedema, soft-tissue oedema and synovitis in paediatric patients. Methods: A total of 52 patients (mean age 11 ± 5 years) with bone marrow oedema (n = 31), soft-tissue oedema (n = 20) and synovitis (n = 15) were examined with transversal diffusion-weighted single-shot echoplanar imaging in addition to standard MR sequences (T2W TIRM, T1W pre- and post-contrast). Diffusion-weighted images were used for lesion detection and apparent diffusion coefficient (ADC, unit × 10-3 mm2/s) values were measured with ROI technique on ADC maps. Results: In 50 of 52 patients, DWI delineated the lesion of interest corresponding to pathological signal increase on standard sequences. Mean ADC was 1.60 ± 0.14 (range 1.38 - 1.99) in osseous lesions, 1.72 ± 0.31 (range 1.43 - 2.56) in soft tissue oedema and 2.82 ± 0.24 (range 2.47 - 3.18) for joint effusion (ANOVA p<0.001). No significant difference in mean ADC was seen for inflammatory vs. non-inflammatory lesions. Relative signal intensity of oedema was similar for DWI and T2W TIRM. DWI visualised synovial restricted diffusion with a mean ADC of 2.12 ± 0.45 in 12 of 15 patients with synovitis. Conclusions: Diffusion-weighted MRI reliably visualises osseous and soft tissue oedema, as compared to standard sequences. DWI of synovitis is feasible in large joints and presents a novel approach to contrast-free imaging of synovitis. Whole-body DWI for chronic non-bacterial osteomyelitis should be evaluated in future studies.