ABSTRACT
Dynamic contrast-enhanced MR imaging (DCE-MRI) may act as a biomarker for successful cancer therapy. Simple, reproducible techniques may widen this application. This paper demonstrates a single slice imaging technique. The image acquisition is performed in less than 500 ms making it relatively insensitive to respiratory motion. Data from phantom studies and a reproducibility study in solid human tumours are presented. The reproducibility study showed a coefficient of variation (CoV) of 19.1% for K(trans) and 15.8% for the initial area under the contrast enhancement curve (IAUC). This was improved to 16 and 13.9% if tumours of diameter less than 3 cm were excluded. The individual repeatability (the range within which individual measurements are expected to fall) was 30.6% for K(trans) and 26.5% for IAUC for tumours greater than 3 cm diameter. This approach to DCE-MRI image acquisition can be performed with standard clinical scanners, and data analysis is straightforward. For treatment trials with 10 patients in a cohort, the CoV implies that the method would be sensitive to a treatment effect of greater than 18%. The individual repeatability is well inside the 40% change shown to be important in clinical studies using this DCE-MRI technique.
Subject(s)
Angiogenesis Inhibitors/therapeutic use , Colorectal Neoplasms/diagnosis , Liver Neoplasms/diagnosis , Lung Neoplasms/diagnosis , Magnetic Resonance Imaging/methods , Phthalazines/therapeutic use , Pyridines/therapeutic use , Receptors, Vascular Endothelial Growth Factor/antagonists & inhibitors , Area Under Curve , Colorectal Neoplasms/drug therapy , Colorectal Neoplasms/pathology , Contrast Media , Drug Monitoring , Humans , Image Processing, Computer-Assisted , Liver Neoplasms/drug therapy , Liver Neoplasms/secondary , Lung Neoplasms/drug therapy , Lung Neoplasms/secondary , Phantoms, Imaging , Reproducibility of ResultsABSTRACT
Simulator radiographs taken as a record of breast radiotherapy planning often show ill defined breast tissue margins because exposure parameters are set to optimize visualization of the chest wall rather than the bulk of the breast. This creates difficulties when using simulator images as reference images in verification by comparing with either portal film or images from an electronic portal imaging device. Our aim was to improve breast images taken at simulation without changing exposure parameters that have been optimized for visualization of the chest wall. This has been achieved via an external filter to be used when taking radiographs with the treatment simulator. The filter is made of stainless steel coated with tin and is shaped to maintain acceptable imaging of the chest wall by covering only the section of field anterior to the chest wall. Radiographs of breast simulations using the filter have been accepted as satisfactory by both clinicians and radiographers. The filter is now in routine clinical use for breast and chest wall treatment simulation.
