Dynamics of angiogenesis and cellularity in rabbit VX2 tumors using contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging

Abstract

A number of studies have demonstrated that dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) may be used to evaluate microvessel density (MVD), and may quantitatively reflect tumor angiogenesis. To investigate the dynamics, including angiogenesis and tumor cellularity, of rabbit VX2 tumors during the 4 weeks following tumor implantation, the present study used DCE-MRI combined with diffusion-weighted imaging (DWI) to scan the tumors at 3 days, and then at 1, 2, 3 and 4-week intervals, following tumor implantation. The dynamics, volume transfer coefficient (Ktrans) and apparent diffusion coefficient (ADC) of the tumor parenchyma were analyzed. Furthermore, the associations between Ktrans and MVD at 4 weeks after tumor implantation were analyzed. Tumor Ktrans was positively correlated with MVD at 4 weeks (r=0.674, P<0.001). Following tumor implantation, the tumor Ktrans level rose for 2 weeks and then began to decline, reaching its lowest point at 4 weeks (P<0.001). ADC values at 1 week were higher than at 3 days, but declined thereafter (P<0.001). Tumor necrosis appeared by 1 week after tumor implantation. The necrosis degree of tumor was gradually increased from the occurrence of necrosis within the 4-week time span of the present study (1 vs. 2 weeks, P=0.008; 2 vs. 3 weeks, P<0.001; 3 vs. 4 weeks, P<0.001). The present study identified that tumor angiogenesis is a dynamic process that serves a function in tumor growth, and that DCE-MRI may reflect tumor parenchymal MVD and be useful in evaluating angiogenesis.

Treatment Effect of a Vascular-Disrupting Agent Dynamically Monitored by DWI: An Animal Experimental Study

“…is may be due to the ischemia and necrosis in VX2 tumors, which lead to an increase in the mean ADC values of the entire tumor in the control group at a later stage of the experiment and also concealed the decrease in the ADC value of the solid component of the tumor caused by tumor cell hyperplasia. Li et al [26] found that the degree of necrosis in the rabbit VX2 tumor gradually increased since the occurrence of necrosis within the 4-week time span of their study, proving that VX2 tumors are prone to ischemia and necrosis.…”

Multiplex fluorescent immunohistochemistry quantitatively analyses microvascular density (MVD) and the roles of TGF-β signalling in orchestrating angiogenesis in colorectal cancer

“…Angiogenesis is regulated by multiple growth factors, including VEGF, PDGF, and FGF ( 4 , 5 ). Microvascular density (MVD) is considered the ‘gold standard’ for measuring tumour angiogenesis ( 6 ). Many studies have shown that MVD could have potential value as a prognostic biomarker of tumours ( 7 ).…”

To see or not to see — what renders prostate cancer visible?

“…There are many reasons to think that tumours that we 'see' might be more aggressive compared to those we cannot -over and above issues relating to tumour volume (a proxy for the number of tumour cells present). The observation that a given tumour can exhibit a strong signal on the dynamic contrast enhanced (DCE) T1-gadolinium sequence implies the establishment of an abnormal, tumour-mediated blood supply that may well be a condition for further proliferation (6). The presence of a low apparent diffusion coefficient (ADC) tends to be associated with greater cell density -a status that is conferred by a tendency towards anaplasia and invasion resulting in a re-modelling of tissue microstructure.…”