Molecular Imaging Insight - May 2008 - (Page 19) The site also uses the Biograph 64 TruePoint for 4D PET imaging. It’s not uncommon for lung cancer patients to present with inflammatory tissue around the malignant nodule. “It’s a challenge to determine which tissue is malignant and which is inflamed. 4D PET outlines the tumor very well, and 4D CT outlines the tumor very well, allowing us to discriminate malignant and benign tissue and appropriately focus the dose.” PET/CT has proven useful in the treatment of locally advanced lung cancer. “It’s difficult to image these patients with conventional PET scans. But PET/CT images reveal the metabolic activity in highly active lymph modes and the precise movement of the primary lung mass,” says Forbes. The scanner delivers a new level of diagnostic accuracy, which, in turn, provides physicians the data needed to more appropriately inform treatment decisions. That is, some patients who initially appeared to be surgical or radiation candidates may be spared from treatments that are not likely to be effective. Another patient population that benefits from PET/CT imaging is esophageal cancer patients. Despite the advances of the last year, Forbes anticipates further improvements over the next year. Siemens new High-Definition PET•CT will improve resolution to 2 mm, providing a means to analyze tiny nodules detected on screening CT studies. “The new [corresponding] software should improve treatment as well by allowing us to better correlate the physiologic uptake of the tumor and its geometric shape on CT studies,” explains Forbes. Other advances could take the form of new tracers. Hypoxic indicators could point to regions where cancer is likely to recur. Looking ahead Maastro Clinic aims to use the Biograph 40 TruePoint PET•CT scanner and TrueD software as a springboard to deliver further improvements in radiation therapy. It plans a host of new trials and protocols this year. Radiation oncologists have known that tumors are heterogeneous for decades; however, until recently, they did not have a tool to differentiate various regions of a tumor. Now, Maastro Clinic intends to tap into the Biograph 40 TruePoint PET•CT and TrueD software to redefine radiation therapy and monitor response to treatment. The latest version of syngo TrueD incorporates deformable registration. “Deformable registration is an amazing technology for advancing assessment of therapy response. It enables us to identify patterns of recurrence within the tumor. Long term, this information will allow us to predict before treatment the risk of tumor relapse for each voxel and give a higher radiation dose to the tumor voxel having a higher risk of local relapse. The concept of ‘pattern of relapse within the tumor’ will revolutionize the approach evaluating tumor response,” explains Lambin. Similarly, Maastro Clinic is using Biograph 40 TruePoint PET•CT during treatment and three months post-treatment in lung and head and neck cancer patients to look at the “metabolic response,” a surrogate endpoint highly correlated to survival and to look at the pattern of relapse within the tumor (van Baardwijck et al, 2007). Finally, Maastro Clinic and Siemens are collaborating on the development of new biomarkers that could answer sophisticated questions about the phenotype of the tumors, or the “tumor passport.” “New agents could determine whether or not a tumor is hypoxic, rapidly proliferating or susceptible to specific receptors. Ultimately, information provided by PET/CT could help physicians adapt treatment, the type of radiation and the type of drug, to each specific patient,” sums Lambin. This will increase the complexity of the decision process dramatically. It will be crucial to have decision support systems to facilitate decisionmaking based on rational arguments and on patient wishes about the best treatment for each patient. An example of such initiative is “Remind CS,” a decision support software for lung cancer, under development in the Image Knowledge Management division of Siemens. Stay tuned. Clinical Studies: References sorted by most recent time of publication Orban de Xivry J, Janssens G, Bosmans G, De Craene M, Dekker A, Buijsen J, van Baardwijk A, De Ruysscher D, Macq B, Lambin P. Tumour delineation and cumulative dose computation in radiotherapy based on deformable registration of respiratory correlated CT images of lung cancer patients. Radiother Oncol. 2007 Oct 11. Bosmans G, van Baardwijk A, Dekker A, Ollers M, Wanders S, Boersma L, Lambin P, De Ruysscher D. Trends in Nodal Volumes and Motion During Radiotherapy for Patients with Stage III Non-Small-Cell Lung Cancer. Int J Radiat Oncol Biol Phys. 2007 Nov 7. Baardwijk van A, Bosmans G, Dekker A, van Kroonenburgh M, Boersma L, Wanders S, Öllers M, Houben R, Minken A, Lambin P, de Ruysscher D. Time trends in the maximal uptake of FDG on PET scan during thoracic radiotherapy. A prospective study in locally advanced non-small cell lung cancer (NSCLC) patients. Radiother Oncol 2007 Feb;82(2):145-52. Baardwijk van A, Bosmans G, Boersma L, Buijsen J, Wanders S, Hochstenbag M, Suylen van RJ, Dekker A, Dehing-Oberije C, Houben R, Bentzen SM, Kroonenburgh van M, Lambin P, and Ruysscher MolecularImaging.net de D. PET-CT based auto-contouring in non-small cell lung cancer correlates with pathology and reduces interobserver variability in the delineation of the primary tumor and involved nodes. Int J Radiat Oncol Biol Phys. 2007 Jul 1;68(3):771-8. Van Baardwijk A, Dooms C, van Suylen RJ, Verbeken E, Hochstenbag M, Dehing-Oberije C, Rupa D, Pastorekova S, Stroobants S, Buell U, Lambin P, Vansteenkiste J, de Ruysscher D. The maximum uptake of (18)F-deoxyglucose on positron emission tomography scan correlates with survival, hypoxia inducible factor-1alpha and GLUT-1 in non-small cell lung cancer. Eur J Cancer. 2007 Jun;43(9):1392-8. Bosmans G, Buijsen J, Dekker A, Velders M, Boersma L, de Ruysscher D, Minken A, Lambin P. An “in silico” clinical trial comparing free breathing, slow and respiration correlated computed tomography in lung cancer patients. Radiother Oncol. 81 (2006) 73-80. Bosmans G, van Baardwijk A, Dekker A, Ollers M, Boersma L, Minken A, Lambin P, De Ruysscher D. Intra-patient variability of tumor volume and tumor motion during conventionally fractionated radiotherapy for locally advanced non-small-cell lung cancer: a prospective clinical study. Int J Radiat Oncol Biol Phys. 2006 Nov 1;66(3):748-53. De Ruysscher D, Bremer RH, Koppe F, Wanders S, van Haren E, Hochstenbag M, Geeraedts W, Pitz C, Simons J, ten Velde G, Dohmen J, Snoep G, Boersma L, Verschueren T, van Baardwijk A, Dehing C, Pijls M, Minken A, Lambin P. Omission of elective node irradiation on basis of CT-scans in patients with limited disease small cell lung cancer: a phase II trial. Radiother Oncol. 2006 Sep;80(3):307-12. van Baardwijk A, Baumert BG, Bosmans G, van Kroonenburgh M, Stroobants S, Gregoire V, Lambin P, De Ruysscher D. The current status of FDG-PET in tumour volume definition in radiotherapy treatment planning. Cancer Treat Rev. 2006 Jun;32(4):245-60. De Ruysscher D, Wanders S, Van Haren E, Hochstenbag M, Geeraedts W, Utama I, Simons J, Dohmen J, Rhami A, Buell U, Thimister P, Snoep G, Boersma L, Verschueren T, Van Baardwijk A, Minken A, Bentzen SM, Lambin Ph. Selective mediastinal node irradiation on basis of the FDG-PET scan in patients with non-small cell lung cancer: A prospective clinical study. Int. J. Radiation Oncology Biol. Phys., Vol. 62, No. 4, pp. 988-994, 2005. May 2008 | Molecular Imaging Insight 1 http://MolecularImaging.net
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