Increased Delay Between Gadolinium Chelate Administration and T1-Weighted Magnetic Resonance Imaging Acquisition Increases Contrast-Enhancing Tumor Volumes and T1 Intensities in Brain Tumor Patients

Objectives The aim of this study was to evaluate the impact of delayed T1-weighted (T1-w) MRI acquisition after gadolinium chelate administration on brain tumor volumes and T1-w intensities. Materials and Methods Fifty-five patients with histologically confirmed, contrast-enhancing intra-axial brain tumors were analyzed in this prospective test-retest study. Patients underwent 2 consecutive 3 T MRI scans (separated by a 1-minute break) during routine follow-up with contrast-enhanced T1 (ceT1-w), T2, and FLAIR acquisition. Macrocyclic gadolinium chelate–based contrast agent was only administered before the first ceT1-w acquisition; median latency to ceT1-w acquisition was 6.72 minutes (IQR, 6.53–6.92) in the first and 16.27 minutes (IQR, 15.49–17.26) in the second scan. Changes in tumor volumes and relative ceT1-w intensities between the 2 acquisitions were quantitatively assessed following semiautomated tumor segmentation (separately for contrast-enhancement [CE], necrosis [NEC], and nonenhancing [NE] tumor). Results Semiautomatically segmented CE tumor volumes were significantly larger in the second acquisition (median +32% [1.2 cm3]; IQR, 16%–62%; P

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