Cluster analysis of BOLD fMRI time series in tumors to study the heterogeneity of hemodynamic response to treatment

• Published in: Magnetic resonance in medicine Vol. 49; no. 6; pp. 985 - 990
• Main Authors: Baudelet, Christine, Gallez, Bernard
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.06.2003; Williams & Wilkins
• Subjects: Animals; Biological and medical sciences; BOLD; Calcium Channel Blockers - pharmacology; Cluster Analysis; Data Interpretation, Statistical; Fibrosarcoma - blood supply; Fibrosarcoma - physiopathology; Flunarizine - pharmacology; Hindlimb; K-means; Magnetic Resonance Imaging; Male; Medical sciences; Mice; MRI; oxygen; Oxygen Consumption - drug effects; Regional Blood Flow - drug effects; tumor; K-means; BOLD; cluster analysis; MRI; oxygen; tumor
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.10468

BOLD‐contrast functional MRI (fMRI) has been used to assess the evolution of tumor oxygenation and blood flow after treatment. The aim of this study was to evaluate K‐means‐based cluster analysis as a exploratory, data‐driven method. The advantage of this approach is that it can be used to extract information without the need for prior knowledge concerning the hemodynamic response function. Two data sets were acquired to illustrate different types of BOLD fMRI response inside tumors: the first set following a respiratory challenge with carbogen, and the second after pharmacological modulation of tumor blood flow using flunarizine. To improve the efficiency of the clustering, a power density spectrum analysis was first used to isolate voxels for which signal changes did not originate from noise or linear drift. The technique presented here can be used to assess hemodynamic response to treatment, and especially to display areas of the tumor with heterogeneous responses. Magn Reson Med 49:985–990, 2003. © 2003 Wiley‐Liss, Inc.