| Zugriffsnummer | 43258 |
| Dokumenttyp | Zeitschriftenartikel |
| Peer Review | mit Peer Review |
| Sprache | Englisch |
| Titel | High resolution time-of-flight MR-angiography at 7 T exploiting VERSE saturation, compressed sensing and segmentation |
| Autor(in); Institution |
Meixner, C.; Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Liebig, P.; Siemens Healthcare GmbH, Erlangen, GERMANY; Max Schaldach-Stiftungsprofessur für Biomedizinische Technik (MSBT), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Speier, P.; Siemens Healthcare GmbH, Erlangen, GERMANY
Forman, C.; Siemens Healthcare GmbH, Erlangen, GERMANY
Hensel, B.; Max Schaldach-Stiftungsprofessur für Biomedizinische Technik (MSBT), Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Schmidt, M.; Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Saake, M.; Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Uder, M.; Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Doerfler, A.; Department of Neuroradiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
Heidemann, R.; Siemens Healthcare GmbH, Erlangen, GERMANY
Schmitter, Sebastian; 8.1, Biomedizinische Magnetresonanz, PTB-Berlin
Nagel, A.; Institute of Radiology, University Hospital Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY; Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, GERMANY; Institute of Medical Physics, Friedrich-Alexander Universität Erlangen-Nürnberg (FAU), Erlangen, GERMANY
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| Quelle/Jahr | Magnetic Resonance Imaging: 63 (2019), 11, 193 - 204 |
| ISSN | 0730-725X (PRINT) ; 1873-5894 (ONLINE) |
| DOI | |
| Verlag | Amsterdam [u.a.]: Elsevier |
| Freie Schlagworte | 7 Tesla ; Compressed sensing ; MR-angiography ; Time-of-flight ; Ultra-high field ; VERSE |
| Zusammenfassung | BACKGROUND: 3D Time-of-Flight (TOF) MR-angiography (MRA) substantially benefits from ultra-high magnetic field strengths (≥7 T) due to increased Signal-to-Noise ratio and improved contrast. However, high-resolution TOF-MRA usually requires long acquisition times. In addition, specific absorption rate constraints limit the choice of optimal pulse sequence parameters, especially if venous saturation is employed. PURPOSE: To implement and evaluate an arterial TOF-MRA for accelerated high-resolution angiography at ultra-high magnetic field strength. FIELD STRENGTHS/SEQUENCE: 7 T modified gradient-echo TOF sequence including venous saturation using Variable-Rate Selective Excitation (VERSE), Compressed Sensing (CS) and sparse application of saturation pulses, called segmentation, were included for acceleration. ASSESSMENT: To analyze the acceleration techniques all volunteers were examined with the same protocols. CS with different sampling patterns and regularization factors as well as segmentation were applied for acceleration. For comparison, conventional acceleration techniques were applied (GRAPPA PAT 3 and Partial Fourier (6/8 in slice/phase encoding)). Images were co-registered and 40 mm thick transversal maximum intensity projections were created to calculate the relative number of vessels. To analyze the visibility of small vessels, the lenticulostriate arteries (LSA) were examined. This was done via multiscale vessel enhancement filtering in a VOI and quantification via Fiji ImageJ as well as qualitatively evaluation by two radiologists. Additionally, the venous/arterial vessel-to-background ratios (vVBR/aVBR) were calculated for chosen protocols. RESULTS: For the acceleration of a high resolution TOF-MRA (0.31 mm isotropic), under-sampling of 9.6 showed aliasing artifacts, whereas 7.2 showed no aliasing. The regularization factor R had a strong impact on the image quality according to smoothing (R = 0.01 to R = 0.005) and noise (R = 0.0005 to R = 0.00005). With the alternating sampling patterns it was shown that the k-space center should not be under-sampled too much. Additionally segmentation could be verified to be feasible for stronger acceleration with sufficient venous suppression. CONCLUSION: The combination of several independent techniques (VERSE, CS with acceleration factor 7.2, R = 0.001, Poisson disc radius of 80%, 3 segments) enables the application of high-resolution (0.31 mm isotropic) TOF-MRA with venous saturation at 7 T in clinical time settings (TA ≈ 5 min) and within the SAR limits. |
| Themenbereich der Metrologie | Metrologie in der Medizin |
Zitierung
Meixner, C., Liebig, P., Speier, P., Forman, C., Hensel, B., Schmidt, M., Saake, M., Uder, M., Doerfler, A., Heidemann, R., Schmitter, S., & Nagel, A. (2019). High resolution time-of-flight MR-angiography at 7 T exploiting VERSE saturation, compressed sensing and segmentation. Magnetic Resonance Imaging, 63(11), 193–204. https://doi.org/10.1016/j.mri.2019.08.014