FIG 2. Axial T2-weighted (T2W), T1-weighted Gd-enhanced (T1W Gd), hemodynamic (rCBV), and diffusion (ADC) MR images and selected proton MR spectra (1–5) from a multivoxel spectroscopic data set in a 6-month-old male infant with a choroid plexus carcinoma. The lesion contains a large central area of low or normal signal intensity on the T2-weighted image, and it has inhomogeneous intense enhancement on the T1-weighted Gd-enhanced image, with nonenhancing areas that represent necrotic and/or cystic degeneration. The rCBV image shows increased perfusion (bright regions) in the areas of enhancement, whereas the corresponding areas on the ADC image appear hypointense. Selected proton MR spectra (1–4) show high Cho peaks, which are believed to correspond to areas of viable tumor. MR spectra 1 and 2 correspond to areas of low or normal signal intensity on the T2-weighted image that do not enhance on the T1-weighted; theses areas appear hypointense on both rCBV and ADC images. MR spectra 3 and 4 correspond to hypointense areas on the T2-weighted image that enhance; these appear hyperintense and hypointense on rCBV and ADC images. MR spectrum 5 shows only a high lipid (L) value, which is thought to indicate necrosis; this finding corresponds to a hypointense region on the T2-weighted image that does not enhance on the T1-weighted Gd-enhanced and rCBV images and appears hyperintense on the ADC image. High lipid values are also shown on MR spectra 3 and 4, in addition to high Cho values; this pattern indicates a mixture of viable tumor and necrosis. The Figure illustrates a positive relationship between Cho and rCBV values and an inverse relationship between Cho and ADC values. It shows that Cho (or active tumor) was detected in enhancing regions of the tumor and beyond.