Research Focus

Dual Energy CT: two tubes using two different x-ray spectra rotate around the patient.
© dkfz.de

This division focuses on dual energy CT (DECT) in oncology. „Dual Source Dual Energy CT“ is a promising development in CT technology using two x-ray spectra. Based on the different atomic numbers of soft tissues and contrast agent and the associated spectral properties, a material differentiation is possible without increasing radiation dose, which enables multiple clinical benefits.

DECT for improved detection of melanoma metastases

Iodine map based on dual energy CT (right): compared to conventional CT (Left), diagnosis of muscle metastases is improved.
© dkfz.de

Contact: Dr. med. Dipl.-Phys. Monika Uhrig

In oncology, DECT improves detection of metastases. Iodine maps based on spectral dual energy CT reconstructions visualize enhancing lesions. Especially melanoma metastases in musculature profit from iodine maps. (The study „Improved Detection of Melanoma Metastases Using Iodine Maps from Dual Energy CT“ has been awarded by the Trainee Research Award 2015 of the Radiological Society of North America RSNA.)

 

Iodine map based on dual energy CT (right): compared to conventional CT (Left), diagnosis of muscle metastases is improved

Fig3a: Iodine map from DECT: the arrow indicates a melanoma metastasis with central necrosis and periperal contrast enhancement. Fig3b: Quantification of iodine improves monitoring of targeted therapies. Therapy responder show decreased iodine uptake in follow up (FU) examinations.
© dkfz.de

Contact: Dr. med. Dipl.-Phys. Monika Uhrig

Furthermore, DECT improves therapy monitoring of targeted therapies, where measuring size can be insufficient. DECT provides quantification of iodinated contrast agent uptake, objectively documenting in a single number the absolute amount of iodine in a lesion and avoiding a preceding unenhanced scan. In contrast to density measurements, iodine quantification is not influenced by tissue modifications such as necrosis and hemorrhage, which can alter attenuation in CT and mimic reduced or increased contrast agent uptake. Iodine uptake could be a new parameter directly related to vital and vascularized tumor tissue.

DECT histogram analysis in therapy monitoring of targeted therapies

Fig4: Histogram analyses of melanoma metastasis, based on spectral examinations with dual energy CT. responder to targeted therapies show a typical pattern with decreased mean value, maximum and standard deviation.
© dkfz.de

Contact: Dr. med. Dipl.-Phys. Monika Uhrig

The absolute amount of the quantified contrast medium uptake can be investigated further, focusing on finding a typical pattern of contrast medium distribution under targeted therapy. This is realized by performing histogram analysis of iodine maps based on DECT data. Responder to targeted therapies show significantly decreased values for mean, maximum and standard deviation of histograms.

DECT for diagnosis of pulmonary embolism

Fig5: Pulmonary lung embolus on iodine map (left): the thrombus (arrow) is highlighted red. On the right the corresponding conventional CT.
© dkfz.de

Contact: Dr. med. Dipl.-Phys. Monika Uhrig

Furthermore, diagnosis of pulmonary arterial emboli can be supported by providing vessel reconstructions and highlighting thrombi. This is of clinical interest in oncology regarding that malignancy is the strongest predictor for venous thromboembolism.

References

Uhrig M, Simons D, Bonekamp D, Schlemmer HP. Improved detection of melanoma metastases by iodine maps from dual energy CT. Eur J Radiol. 2017 May;90:27-33. doi: 10.1016/j.ejrad.2017.02.024. Epub 2017 Feb 17. PubMed PMID: 28583644.

Uhrig M, Simons D, Kachelrieß M, Pisana F, Kuchenbecker S, Schlemmer HP.Advanced abdominal imaging with dual energy CT is feasible without increasing radiation dose. Cancer Imaging. 2016 Jun 21;16(1):15. doi: 10.1186/s40644-016-0073-5. PubMed PMID: 27329159; PubMed Central PMCID: PMC4915171.

Uhrig M, Simons D, Ganten MK, Hassel JC, Schlemmer HP. Histogram analysis of iodine maps from dual energy computed tomography for monitoring targeted therapy of melanoma patients. Future Oncol. 2015;11(4):591-606. doi: 10.2217/fon.14.265. PubMed PMID: 25686115.

Uhrig M, Sedlmair M, Schlemmer HP, Hassel JC, Ganten M. Monitoring targeted therapy using dual-energy CT: semi-automatic RECIST plus supplementary functional information by quantifying iodine uptake of melanoma metastases. Cancer Imaging. 2013 Jul 22;13(3):306-13. doi: 10.1102/1470-7330.2013.0031. PubMed PMID: 23876444; PubMed Central PMCID: PMC3719051.

Uhrig M, Hassel JC, Schlemmer HP, Ganten MK. Therapy response assessment in metastatic melanoma patients treated with a BRAF inhibitor: adapted Choi criteria can reflect early therapy response better than does RECIST. Acad Radiol. 2013 Apr;20(4):423-9. doi: 10.1016/j.acra.2012.09.029. PubMed PMID: 23498982.

Links

 

Former projects:

„Radiology infrastructure for non-radiologists: building a mobile and cost-effective DICOM viewing based forensic-radiologic network“

D Simons, I Reicht, M Uhrig, M Fangerau, K Yen, H Schlemmer

DOI: 10.1055/s-0035-1550791

https://www.thieme-connect.com/products/ejournals/abstract/10.1055/s-0035-1550791

Uhrig, M., Thieke, C., Alonso, F., Küfer, K., Monz, M., Scherrer, A. and Oelfke, U. (2005), SU-FF-T-112: First Evaluation of a New Multicriteria Optimization Tool-Investigation of Pareto-Surfaces for IMRT Prostate Plans. Med. Phys., 32: 1975. doi:10.1118/1.1997783

http://onlinelibrary.wiley.com/doi/10.1118/1.1997783/full

Craft, D., Bortfeld, T., Halabi, T., Martin, B. and Uhrig, M. (2005), SU-FF-T-116: Multicriteria IMRT Planning with Equivalent Uniform Dose (EUD) Objectives: Tumor Dose Homogeneity vs. Critical Structure Sparing. Med. Phys., 32: 1976. doi:10.1118/1.1997787

http://onlinelibrary.wiley.com/doi/10.1118/1.1997787/full

 

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