DTI in der Diagnostik der zervikalen Myelopathie

Zusammenfassung

Die degenerative zervikale Myelopathie (DCM) ist die häufigste Form der Rückenmarksaffektion im Erwachsenenalter. Die zugrundeliegenden pathophysiologischen Veränderungen sind komplex und eine operative Therapie ist in aller Regel spätestens dann notwendig, wenn relevante klinische Symptome einer stenosebedingten Rückenmarkskompression vorliegen. Für die Planung der Operation ist eine akkurate bildgebende Diagnostik essenziell. Diese soll dabei helfen, die zur klinischen Symptomatik beitragenden Wirbelsäulensegmente zu identifizieren.

Die konventionelle Magnetresonanztomografie (MRT) ist das heutzutage am häufigsten angewendete bildgebende Verfahren bei DCM, da sich v. a. T2-gewichtete MRT-Sequenzen hervorragend für die morphologische Beurteilung der Rückenmarkskompression und die Identifikation einer Myelomalazie („Myelopathiezeichen“) eignen. Insbesondere bei multisegmentalen degenerativen Veränderungen kann die Grenze der diagnostischen Aussagekraft des MRTs jedoch schnell erreicht werden.

Die Diffusion Tensor Bildgebung (diffusion tensor imaging, DTI) ist eine auf der MRT basierende, neuartige Untersuchungsmodalität, die auf der Messung der Diffusionseffekte von Wassermolekülen auf zellulärer Ebene basiert und eine Beurteilung der Integrität der weißen Rückenmarkssubstanz ermöglicht. Die beiden wichtigsten DTI-Größen, FA (fraktionelle Anisotropie) und ADC (apparent diffusion coefficient), stellen Surrogatparameter für das Ausmaß der strukturellen Myelonschädigung dar und zeigen Unterschiede zwischen DCM-Patienten und gesunden Probanden. Ein Vorteil dieser Technik könnte in einer sensitiven und frühen Detektion einer Rückenmarksschädigung liegen, zudem ist die Nutzung als prognostischer Marker oder bei der Operationsplanung denkbar.

Unser Artikel beschäftigt sich mit den Einsatzmöglichkeiten des DTI bei der zervikalen Myelopathie und gibt einen Ausblick auf mögliche zukünftige Entwicklungen.

Abstract

Degenerative cervical myelopathy (DCM) represents the most common spinal cord disorder in adults. The underlying pathophysiology is complex and surgery is usually recommended when patients develop clinical signs of spinal cord compression. Accurate imaging is crucial for planning of surgical decompression to keep the surgical trauma as minimal as possible without leaving stenotic levels contributing to myelopathy untreated.

Conventional magnetic resonance imaging (MRI) is the most widely used imaging modality for DCM evaluation, since especially T2-weighted sequences allow for morphological assessment of both compression of and signal changes within the spinal cord. However, conventional MRI is limited when it comes to precise grading of stenosis severity, extent of spinal cord compression and assessment of microstructural damage, particularly in multilevel pathologies.

Diffusion tensor imaging (DTI) is a relatively new MRI-based imaging modality that allows for assessment of white matter integrity by measuring diffusion effects of water molecules. The main DTI indices, fractional anisotropy (FA) and apparent diffusion coefficient (ADC), are surrogate measures for the degree of structural impairment of the spinal cord and show differences between healthy controls and DCM patients. The potential advantage of DTI is to show impairment of spinal cord integrity very sensitively and at an early stage of the disease. Additionally, DTI indices can perspectively be used to predict surgical outcome and might also be helpful in surgical planning.

We illustrate the diagnostic potential of DTI for DCM assessment and give an outlook on future developments.

Schlüsselwörter

Diffusion Tensor Imaging - zervikale Myelopathie - Prädiktor - Operation

Keywords

Diffusion Tensor Imaging - cervical myelopathy - predictive factor - surgery

Publication History

Article published online:
29 October 2020

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