Dynamic Contrast-Enhanced MRI in Head-and-Neck Cancer: The Impact of Region of Interest Selection on the Intra- and Interpatient Variability of Pharmacokinetic Parameters

• Published in: International journal of radiation oncology, biology, physics Vol. 82; no. 3; pp. e345 - e350
• Main Authors: Craciunescu, Oana I., Ph.D, Yoo, David S., M.D., Ph.D, Cleland, Esi, M.S, Muradyan, Naira, Ph.D, Carroll, Madeline D., M.S.A, MacFall, James R., Ph.D, Barboriak, Daniel P., M.D, Brizel, David M., M.D
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2012
• Subjects: Angiogenesis Inhibitors - therapeutic use; Antibodies, Monoclonal, Humanized - therapeutic use; Area Under Curve; Bevacizumab; Chemoradiotherapy - methods; Cisplatin - therapeutic use; Contrast Media - pharmacokinetics; DCE-MRI; DISPERSIONS; Erlotinib Hydrochloride; Gadolinium DTPA - pharmacokinetics; HEAD; Head and neck cancer; Head and Neck Neoplasms - blood supply; Head and Neck Neoplasms - metabolism; Head and Neck Neoplasms - pathology; Head and Neck Neoplasms - therapy; Hematology, Oncology and Palliative Medicine; Humans; Image Enhancement - methods; LYMPH NODES; Lymphatic Metastasis; Magnetic Resonance Imaging - methods; Microcirculation; Molecular Targeted Therapy - methods; NECK; NEOPLASMS; NMR IMAGING; North Carolina; PATIENTS; Pharmacokinetic analysis; PHYSIOLOGY; Quinazolines - therapeutic use; Radiology; RADIOLOGY AND NUCLEAR MEDICINE; RADIOTHERAPY; ROI; TRANSFER FUNCTIONS; North Carolina; Head and neck cancer; DCE-MRI; ROI; Pharmacokinetic analysis
• ISSN: 0360-3016; 1879-355X
• DOI: 10.1016/j.ijrobp.2011.05.059

Purpose Dynamic contrast–enhanced (DCE) MRI-extracted parameters measure tumor microvascular physiology and are usually calculated from an intratumor region of interest (ROI). Optimal ROI delineation is not established. The valid clinical use of DCE-MRI requires that the variation for any given parameter measured within a tumor be less than that observed between tumors in different patients. This work evaluates the impact of tumor ROI selection on the assessment of intra- and interpatient variability. Method and Materials Head and neck cancer patients received initial targeted therapy (TT) treatment with erlotinib and/or bevacizumab, followed by radiotherapy and concurrent cisplatin with synchronous TT. DCE-MRI data from Baseline and the end of the TT regimen (Lead-In) were analyzed to generate the vascular transfer function (Ktrans ), the extracellular volume fraction (ve ), and the initial area under the concentration time curve (iAUC1 min ). Four ROI sampling strategies were used: whole tumor or lymph node (Whole), the slice containing the most enhancing voxels (SliceMax), three slices centered in SliceMax (Partial), and the 5% most enhancing contiguous voxels within SliceMax (95Max). The average coefficient of variation (aCV) was calculated to establish intrapatient variability among ROI sets and interpatient variability for each ROI type. The average ratio between each intrapatient CV and the interpatient CV was calculated (aRCV). Results Baseline primary/nodes aRCVs for different ROIs not including 95Max were, for all three MR parameters, in the range of 0.14–0.24, with Lead-In values between 0.09 and 0.2, meaning a low intrapatient vs. interpatient variation. For 95Max, intrapatient CVs approximated interpatient CVs, meaning similar data dispersion and higher aRCVs (0.6–1.27 for baseline) and 0.54–0.95 for Lead-In. Conclusion Distinction between different patient’s primary tumors and/or nodes cannot be made using 95Max ROIs. The other three strategies are viable and equivalent for using DCE-MRI to measure head and neck cancer physiology.