Monitoring of Tumor Microcirculation during Fractionated Radiation Therapy in Patients with Rectal Carcinoma: Preliminary Results and Implications for Therapy

Abstract

Dynamic T1 mapping provides a suitable tool for monitoring tumor microcirculation during chemoirradiation and offers the potential for individual optimization of therapeutic procedures. Furthermore, these results indicate that the PI map may serve as a prognostic factor.

Noninvasive monitoring of radiotherapy-induced microvascular changes using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) in a colorectal tumor model

“…Large, single RT doses disrupt the endothelial lining and cause a short-term increase in endothelial permeability. Smaller or fractionated doses, however, tend to decrease vascular permeability or cause no (30). They calculated a perfusion index from the shape of the arterial and tumor tissue curves and found this value to be significantly increased up to 2 weeks after the start of chemoradiation.…”

MR in oncology drug development

“…In general, these studies have shown that there is a progressive decrease in MR parameters such as enhancement or K trans which is associated with a decrease in tumor size following chemotherapy and that an increase or no change in such parameters is seen in those patients with progressive disease (40,41). Other studies have reported similar effects following radiotherapy in rectal and cervix cancers (42)(43)(44)(45) and androgen deprivation in prostate cancer (46). The reasons for these changes in DCE-MRI with a wide variety of different anti-cancer therapies might be because a proportion of their antitumor efficacy is due to direct effects on the vasculature, or that tumor cell kill results in a subsequent change in the tumor microcirculation.…”

Dynamic T1 mapping predicts outcome of chemoradiation therapy in primary rectal carcinoma: Sequence implementation and data analysis

“…Details of inclusion criteria and therapy protocols are described elsewhere (7). In short, to minimize factors influencing microcirculatory parameters, a homogenous patient group was examined with respect to tumor type, stage, grading, and treatment.…”

“…The quantification of concentration-time curves is, thereby, based on the widely used assumption of a linear relationship between changes in longitudinal relaxation rate, R 1 ϭ 1/T 1 , and CA concentration, which has recently been demonstrated (4). The T 1 -mapping technique has already been successfully used to assess microcirculatory changes in primary rectal carcinoma during combined chemoradiation therapy (7); therapy outcome could be predicted based on pretherapy examinations (8). For these studies, a prolonged bolus injection of the CA was utilized and a simple data analysis scheme was applied using the so-called PI value, calculated as the initial slope of the tissue CA concentration-time curve divided by the maximum of the arterial CA concentration.…”