Imaging tumour angiogenesis

Abstract

The development of neovasculature via angiogenesis is a vital component of many normal physiological processes and a number of disease states. Neovascularisation is critical for the growth of malignant tumours and for the development and survival of metastases. Recently, the potential of non-invasive imaging for the functional characterisation of neovasculature has become realised. In this review we describe the process of tumour angiogenesis for radiologists and present a summary of the most available computed tomography/magnetic resonance imaging techniques that can depict the functional vascular status of human tumours.

Figure 1

CT and T1-weighted images of the liver in a patient with metastatic colorectal cancer. The MRI scans (top row) were acquired before and 36 s after 0.1 mol kg body weight of Gd-DTPA contrast medium. The CT images (bottom row) were acquired before and 35 s after 50 ml of iodinated contrast medium (300 mg I ml). These represent the standard doses of contrast medium used for T1-weighted DCE-MRI and functional CT. The CT images are acquired at 80 kV, which is optimal for demonstrating contrast medium uptake. Note that, even when these technical factors are taken into account, the signal to noise ratio for MRI is better than for CT. Corresponding parametric maps derived from the dynamic data are shown together with the quantification method that has been used.

Figure 2

Typical DSC-MRI study in a patient with breast cancer. Gd-DTPA contrast medium (0.2 mmol kg body weight) was administered after the 10th baseline data point acquisition. Images were acquired every 2 s. The first pass susceptibility effects cause marked darkening of the tumour with little alteration of the fibro-glandular breast parenchymal tissue. The recirculation phase is not well appreciated. The signal intensity fails to return to baseline because of marked leakage of contrast medium out of the vascular space.

Figure 3

Typical T1-weighted DCE-MRI study in the same patient shown in Fig. 2. Gd-DTPA contrast medium (0.1 mmol kg body weight) was administered after the 4th baseline data point acquisition. Images were acquired every 12 s. Marked early enhancement of the breast tumour is seen with washout. The pattern of enhancement is in marked contrast to that observed in Fig. 2.