Division „Spectral Computed Tomography - Dual Energy and Photon-Counting CT in Oncological Imaging” (Dr. med. Dipl.-Phys. Monika Uhrig)
- Research Focus
- Spectral computed tomography for improved detection of melanoma metastases
- Spectral computed tomography in theraphy monitoring of targeted therapies
- Spectral computed tomography histogram analysis in therapy monitoring of targeted therapies
- Spectral computed tomography for diagnosis of pulmonary embolism
Research Focus
Fig 1a: Multienergy CT with photon-counting detectors Fig1b: Dual Energy CT: two tubes using two different x-ray spectra rotate around the patient.
© dkfz.de
This division focuses on spectral computed tomography in oncology. This includes dual-as well as multienergy CT. „Dual Source Dual Energy CT“ (DECT) is a promising development in CT technology using two x-ray spectra of two rotating x-ray sources. Multienergy CT can be realized by innovative photon-counting detectors, allowing counting single photons and measuring their energy. Based on the different atomic numbers of soft tissues and contrast agent and the associated spectral properties, dual- and multienergy CT enables a material differentiation and ultra-high spatial resolution.
Spectral computed tomography 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.)
Spectral computed tomography in theraphy monitoring of targeted therapies
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.
Spectral computed tomography 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.
Spectral computed tomography 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