Huyen Thanh Nguyen PhD, Presenter: Nothing to Disclose

Kamal S. Pohar MD, Abstract Co-Author: Nothing to Disclose

Amir Mortazavi MD, Abstract Co-Author: Nothing to Disclose

Zarine Ketul Shah MD, Abstract Co-Author: Nothing to Disclose

Debra Zynger MD, Abstract Co-Author: Nothing to Disclose

Michael Vinzenz Knopp MD, PhD, Abstract Co-Author: Nothing to Disclose

Guang Jia PhD, Abstract Co-Author: Nothing to Disclose

Daniel James Clark MS, Abstract Co-Author: Nothing to Disclose

Xiangyu Yang PhD, Abstract Co-Author: Nothing to Disclose

To evaluate the microcirculatory characteristics of papillary bladder cancer stalks detectable on MR images using pharmacokinetic parameters of dynamic contrast-enhanced (DCE) imaging.

Fifty patients with cystoscopy-proven bladder cancer were included in this study. All patients were scanned on a 3T MRI system (Achieva, Philips Healthcare) using a 32-channel phased-array surface coil. T2-weighted (T2W) MRI was performed prior to DCE-MRI. DCE-MRI data were processed on in-house IDL-based software to estimate two pharmacokinetic parameters (Amp, amplitude of signal enhancement and kep, the exchange rate between plasma and interstitial space). With a pre-determined number of three clusters, k-means clustering of the two parameters was performed on the tumors with a stalk shown on either T2W or DCE images to quantitatively and visually assess the microcirculatory properties of bladder cancer stalks.  

7 out of 50 patients had a bladder tumor with a pedicle shown at the base of the tumor on either T2W or DCE images. Compared to the rest of a tumor, the tumor’s stalk showed a delayed signal enhancement on DCE images (Figure 1). Using k-means clustering of the two pharmacokinetic parameters, a bladder tumor was segmented into three clusters with different microcirculatory characteristics: cluster 1 contained voxels of low Amp (low micro-vascularity) and low kep (low permeability); cluster 2 had voxels of high Amp and low kep; and cluster 3 consisted of high Amp and low kep voxels. On cluster color maps, the stalk at the base of a tumor was composed of a majority of tissues with low Amp and low kep. Quantitatively, the volume fraction of cluster 1 in a stalk were 89±8 (%) while that of clusters 2 and 3 were 6±5 (%), 5±5 (%).

Quantitative and visual assessment with DCE-MRI pharmacokinetic parameters showed that the stalk in a bladder tumor was mainly consisted of tissues with low micro-vascularity (low Amp) and low permeability (low kep).

The visualization of bladder tumor’s stalk has been shown to be critical to the determination of stage T1 or lower in bladder cancer, which remains a challenge in bladder cancer staging. This study provides insight into the imaging characteristics that will improve diagnostic readability.

Nguyen, H, Pohar, K, Mortazavi, A, Shah, Z, Zynger, D, Knopp, M, Jia, G, Clark, D, Yang, X, Assessment of Microcirculatory Characteristics in Bladder Cancer Stalks Using Pharmacokinetic Mapped DCE-MRI.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14003645.html