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14. Untersuchung der regionalen Abhängigkeit des zerebralen Sauerstoffumsatzes und neuronaler Aktivität in gesunden Probanden durch dynamische 17O Magnetresonanztomografie bei 7-Tesla

Author

Ebersberger, L, additional, Platt, T, additional, Franke, V, additional, Nagel, A, additional, Umathum, R, additional, Schlemmer, H, additional, Bachert, P, additional, Ladd, M, additional, Korzowski, A, additional, Niesporek, S, additional, and Paech, D, additional

Published
2020
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15. Chemical exchange saturation transfer (CEST) signal intensity at 7T MRI of WHO IV° gliomas is dependent on the anatomic location

Author

Dreher, C., Oberhollenzer, J., Meissner, J., Windschuh, J., Scheunke, P., Regnery, S., Sahm, F., Bickelhaupt , S., Bendszus , M., Wick, W., Unterberg, A., Zaiss, M., Bachert, P., Ladd, M., Schlemmer, H., Radbruch, A., and Paech, D.

Abstract

Background Chemical exchange saturation transfer (CEST) is a novel MRI technique applied to brain tumor patients. Purpose To investigate the anatomic location dependence of CEST MRI obtained at 7T and histopathological/molecular parameters in WHO IV° glioma patients. Study Type Analytic prospective study. Population Twenty‐one patients with newly diagnosed WHO IV° gliomas were studied prior to surgery; 11 healthy volunteers were investigated. Field Strength/Sequence Conventional MRI (contrast‐enhanced, T2w and diffusion‐weighted imaging) at 3T and T2w and CEST MRI at 7T was performed for patients and both patients and volunteers. Assessment Mean CEST signal intensities (nuclear‐Overhauser‐enhancement [NOE], amide‐proton‐transfer [APT], downfield NOE‐suppressed APT [dns‐APT]), ADC values, and histopathological/molecular parameters were evaluated with regard to hemisphere location and contact with the subventricular zone. CEST signal intensities of cerebral tissue of healthy volunteers were evaluated with regard to hemisphere discrimination. Statistical Tests Spearman correlation, Mann–Whitney U‐test, Wilcoxon signed‐rank‐test, Fisher's exact test, and area under the receiver operating curve. Results Maximum APT and dns‐APT signal intensities were significantly different in right vs. left hemisphere gliomas (P = 0.037 and P = 0.007), but not in right vs. left hemisphere cerebral tissue of healthy subjects (P = 0.062‐0.859). Mean ADC values were significantly decreased in right vs. left hemisphere gliomas (P = 0.044). Mean NOE signal intensity did not differ significantly between gliomas of either hemisphere (P = 0.820), but in case of subventricular zone contact (P = 0.047). A significant correlation was observed between APT and dns‐APT and ADC signal intensities (rs = –0.627, P = 0.004 and rs = –0.534, P = 0.019), but not between NOE and ADC (rs = –0.341, P = 0.154). Histopathological/molecular parameters were not significantly different concerning the tumor location (P = 0.104–1.000, P = 0.286–0.696). Data Conclusion APT, dns‐APT, and ADC were inversely correlated and depended on the gliomas' hemisphere location. NOE showed significant dependence on subventricular zone contact. Location dependency of APT‐ and NOE‐mediated CEST effects should be considered in clinical investigations of CEST MRI.

Published
2019

22. Relaxation-compensated amide proton transfer (APT) MRI is a predictor of survival and progression in high-grade glioma patients

Author

Paech, D, additional, Dreher, C, additional, Regnery, S, additional, Meissner, J, additional, Goerke, S, additional, Windschuh, J, additional, Deike-Hofmann, K, additional, Bickelhaupt, S, additional, Radburch, A, additional, Zaiss, M, additional, Unterberg, A, additional, Wick, W, additional, Bendszus, M, additional, Bachert, P, additional, Ladd, M, additional, and Schlemmer, H, additional

Published
2019
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30. „Chemical exchange saturation transfer" (CEST): Magnetresonanztomographie in der onkologischen Diagnostik.

Author

von Knebel Doeberitz, N., Maksimovic, S., Loi, L., and Paech, D.

Abstract

Copyright of Der Radiologe is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Published
2021
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33. What remains after transient global amnesia (TGA)? An ultra‐high field 7 T magnetic resonance imaging study of the hippocampus.

Author

Paech, D., Kuder, T. A., Roßmanith, C., Griebe, M., Eisele, P., Platten, M., Ladd, M. E., Schlemmer, H. ‐P., Gass, A., and Szabo, K.

Subjects
*MAGNETIC resonance imaging, *DIAGNOSTIC imaging, *DIFFUSION magnetic resonance imaging, *AMNESIA
Abstract

Background and purpose: The aim was to study whether ultra‐high field 7 T magnetic resonance imaging (MRI) can demonstrate chronic focal defects in the hippocampus corresponding to the former acute diffusion‐weighted imaging (DWI) lesions and to assess chronic T2‐hyperintense hippocampal lesion load in transient global amnesia (TGA) patients. Methods: Follow‐up of 7 T MRI of the hippocampus was performed in 13 patients with documented hippocampal DWI lesions (detected via 3 T MRI) after acute TGA. The location of the DWI lesions was transformed to 7 T T2 images after data co‐registration. Additionally, the T2‐hyperintense lesion load was estimated in each patient and compared with that of 13 healthy controls. Results: Magnetic resonance imaging (7 T) was performed after a median of 4 months. No structural abnormality at the site of the previous TGA lesion was observed in any case. None of the controls showed DWI lesions. There was no significant difference between patients and controls concerning the number (P = 0.67) or volume (P = 0.45) of T2‐hyperintense hippocampal lesions. Conclusions: Diffusion‐weighted imaging lesions in patients with TGA do not provoke any visible sequelae and do not result in hippocampal cavities. The occurrence of incidental hippocampal T2 lesions after TGA is not more frequent than in controls. [ABSTRACT FROM AUTHOR]

Published
2020
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35. T1ρ-gewichtete dynamische Glukose-verstärkte Magnetresonanztomografie bei Glioblastompatienten

Author

Paech, D, additional, Schuenke, P, additional, Koehler, C, additional, Windschuh, J, additional, Mundiyanapurath, S, additional, Bickelhaupt, S, additional, Bonekamp, D, additional, Bäumer, P, additional, Bachert, P, additional, Ladd, M, additional, Bendszus, M, additional, Wick, W, additional, Unterberg, A, additional, Schlemmer, H, additional, Zaiss, M, additional, and Radbruch, A, additional

Published
2018
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48. Adiabatically prepared spin-lock approach for T1ρ-based dynamic glucose enhanced MRI at ultrahigh fields

Author

Schuenke P, Koehler C, Korzowski A, Windschuh J, Bachert P, Me, Ladd, Sibu Mundiyanapurath, Paech D, Bickelhaupt S, Bonekamp D, Hp, Schlemmer, Radbruch A, and Zaiss M

Abstract

Purpose Chemical exchange sensitive spin-lock and related techniques allow to observe the uptake of administered D-glucose in vivo. The exchange-weighting increases with the magnetic field strength, but inhomogeneities in the radiofrequency (RF) field at ultrahigh field whole-body scanners lead to artifacts in conventional spin-lock experiments. Thus, our aim was the development of an adiabatically prepared T1ρ-based imaging sequence applicable to studies of glucose metabolism in tumor patients at ultrahigh field strengths. Methods An adiabatically prepared on-resonant spin-lock approach was realized at a 7 Tesla whole-body scanner and compared with conventional spin-lock. The insensitivity to RF field inhomogeneities as well as the chemical exchange sensitivity of the approach was investigated in simulations, model solutions and in the human brain. Results The suggested spin-lock approach was shown to be feasible for in vivo application at ultrahigh field whole-body scanners and showed substantially improved image quality compared with conventional spin-lock. The sensitivity of the presented method to glucose was verified in model solutions and a glucose contrast was observed in a glioblastoma patient after intravenous administration of glucose solution. Conclusion An adiabatically prepared spin-lock preparation was presented that enables a homogeneous and chemical exchange sensitive T1ρ-based imaging at ultra-high field whole-body scanners, e.g., for T1ρ-based dynamic glucose enhanced MRI.

50. A systematic review of the clinical effectiveness of 64-slice or higher computed tomography angiography as an alternative to invasive coronary angiography in the investigation of suspected coronary artery disease

Author

Weston Adèle R and Paech Daniel C

Subjects
Diseases of the circulatory (Cardiovascular) system, RC666-701
Abstract

Abstract Background This systematic review summarized recent evidence pertaining to the clinical effectiveness of 64-slice or higher computed tomography angiography (CTA) in patients with suspected coronary artery disease (CAD). If CTA proves to be a successful diagnostic performance measure, it could prevent the use of invasive diagnostic procedures in some patients. This would provide multiple health and cost benefits, particularly for under resourced areas where invasive coronary angiography is not always available. Methods A systematic method of literature searching and selection was employed with searches limited to December 2006 to March 2009. Included studies were quality assessed using National Health and Medical Research Council (NHMRC) diagnostic levels of evidence and a modified Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool. Individual and pooled diagnostic performance measures were calculated using standard meta-analytic techniques at the patient, vessel and segment level. A positive result was defined as greater than or equal to 50% stenosis. Results Twenty-eight studies were included in the systematic review examining 3,674 patients. The primary meta-analysis at the patient-level indicated a sensitivity of 98.2% and specificity of 81.6%. The median (range) positive predictive value (PPV) was 90.5% (76%-100%) and negative predictive value (NPV) 99.0% (83%-100%). In all vessels, the pooled sensitivity was 94.9%, specificity 89.5%, and median (range) PPV 75.0% (53%-95%) and NPV 99.0% (93%-100%). At the individual artery level, overall diagnostic accuracy appeared to be slightly higher in the left main coronary artery and slightly lower in the left anterior descending and circumflex artery. In all segments, the sensitivity was 91.3%, specificity 94.0% and median (range) PPV 69.0% (44%-86%) and NPV 99.0% (98%-100%). Conclusions The high sensitivity indicates that CTA can effectively identify the majority of patients with significant coronary artery stenosis. The high NPV at the patient, vessel and segment level establishes CTA as an effective non-invasive alternative to invasive coronary angiography (ICA) for the exclusion of stenosis.

Published
2011
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