Staging des Rektumkarzinoms mit Hilfe diffusionsgewichteter MRT-Sequenzen - Erste Ergebnisse der StaRdusT-Studie
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Philipps-Universität Marburg
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Abstract
This study shows primary results from the StaRdust-Study – Staging Rectal cancer with diffusion weighted MRI. The aim of this study was to evaluate the performance of diffusion weighted MRI (DWI) for the staging of rectal cancer, especially the detection and differentiation between benign and malignant lymph nodes in patients with primary rectal cancer.
Seventeen patients underwent 1.5T MRI (± neoadjuvant therapy) followed by surgery and histological examination of the resected specimen. Imaging con-sisted of T1- and T2- weighted MRI according to the MERCURY study protocol and additional DWI (b0, 500, 800). Two independent readers analyzed the sig-nal intensity of the primary tumor and each lymph node on DWI. The mean ap-parent diffusion coefficient (ADC) on the corresponding ADC-Map was meas-ured. The mean ADC values were compared between the subgroups based on the status on neoadjuvant therapy (+/- neoadjuvant therapy), MRI parameters (T-/N-/M-stage) and histological parameters (positive/negative lymph node sta-tus, differentiation grade).
Mean tumor ADCs differ significantly between the subgroups with negative and positive lymph node status (1.134 ± 0.2 x 10-3 mm2/s vs 1.241 ± 0.2 x 10-3 mm2/s; p = 0.001). There were no significantly different ADCs between sub-groups based on T-stage, M-stage, +/- neoadjuvant therapy and histological differentiation grade, although lower ADCs were associated with a more ag-gressive tumor profile (positive lymph node status, T3-4 stage, M1 stage). Mean lymph node ADCs differ significantly between groups with and without neoadju-vant therapy (0.773 ± 0.4 x 10-3 mm2/s vs 1.292 ± 0.5 x 10-3 mm2/s; p = 0.025). The group without neoadjuvant therapy showed significantly higher ADCs for metastases than benign lymph nodes (0.958 ± 0.4 x 10-3 mm2/s vs 0.786 ± 0.3 x 10-3 mm2/s; p = 0.017). In the group with neoadjuvant therapy, metastases showed significantly lower ADCs than benign lymph nodes (0.731 ± 0.3 x 10-3 mm2/s vs 1.067 ± 0.4 x 10-3 mm2/s; p = 0.004). With an ADC cut off value of 1.3 x 10-3 mm2/s and 0.5 x 10-3 mm2/s the DWI showed a sensitivi-ty/specificity/PPV/NPV of 100%/75%/75%/100% and 100%/75%/50%/100% respectively in the subgroups without and with neoadjuvant therapy for the de-tection of malignant lymph nodes. Using only the signal intensity the DWI achieved a sensitivity/specificity/PPV/NPV of 100%/0%/29%/0% respectively for the whole study population. There was no significant difference in mean lymph node ADCs based on T-stage, M-stage or histological differentiation grade.
In conclusion, a lower mean tumor ADC seems to be related to a more aggres-sive tumor profile. For patients without neoadjuvant therapy, high ADCs in met-astatic lymph nodes seem to be related to necrosis. After neoadjuvant therapy, low ADCs could reflect cell swelling, fibrosis or viable tumor growth depending on the timing of MRI after therapy onset. Benign lymph nodes can reach high ADCs and a big diameter as well. This seems to reflect unspecific reactive changes like interstitial edema. ADC measurement improves diagnostic preci-sion for the detection of lymph node metastases with DWI compared to signal intensity alone. Because of significant overlap in the ADC values between be-nign and malignant lymph nodes, DWI should be combined with T2w-MRI for lymph node staging.
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Dates
Created: 2015Issued: 2015-02-23
Faculty
Medizin
Publisher
Philipps-Universität Marburg
Language
ger
Data types
DoctoralThesis
Keywords
MRIMRTKolorektales KarzinomRektumkarzinomDWIrectal carcinomadiffusiondiffusion weighted imagingcolorectal carcinoma
DFG-subjects
KernspintomographieMastdarmkrebsDiffusionDickdarmkrebs
DDC-Numbers
610
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Funk, Annika Barbara (1068359463): Staging des Rektumkarzinoms mit Hilfe diffusionsgewichteter MRT-Sequenzen - Erste Ergebnisse der StaRdusT-Studie. : Philipps-Universität Marburg 2015-02-23. DOI: https://doi.org/10.17192/z2015.0136.
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This item has been published with the following license: In Copyright