Normal central zone, DCE-MRI useful in identifying prostate cancer

The normal central zone demonstrates either type one or two enhancement time curves on dynamic contrast-enhanced (DCE)-MRI, potentially allowing for differentiation between the central zone and prostate cancer (PCa), according to a study published in the May issue of Academic Radiology.

The prostate is divided into three glandular zones for management of prostate cancer: the transition zone (TZ), central zone (CZ) and peripheral zone (PZ). Accountable for 25 percent of total prostate volume, the central zone is often mistaken for the transition zone on MRI.

“Unfortunately, T2-weighted and diffusion-weighted MR image features of normal CZ overlap with the features of PCa, and thus CZ can be an important pitfall which mimics PCa, especially at the posterior base, where the prostate is comprised mostly of CZ,” wrote lead author Barry G. Hansford, MD, of the University of Chicago Medicine, and colleagues.

DCE-MRI serves as a possible solution for this issue, though little data exist regarding the technology’s characteristics of the CZ. The authors aimed to determine the detection rate of normal CZ based on described MRI features and to describe the qualitative DCE-MRI characteristics of normal CZ.

The study included 59 patients with prostate cancer who underwent endorectal MRI before prostatectomy. Two readers reviewed T2-weighted images and apparent diffusion coefficient maps that identified normal CZ. Two readers then drew bilateral central zone regions of interest on DCE-MRI in consensus and independently recorded enhancement curve types as type 1 (progressive), type 2 (plateau) and type 3 (wash-out). Normal CZ identification rates and enhancement curve type were recorded and compared for each reviewer.

CZ was identified in 92 to 93 percent of patients on T2-weighted images and 78 percent to 88 percent on apparent diffusion coefficient maps without significant difference between identification rates. The readers rated all central zones as either curve type one or curve type two. There was no statistically significant difference between the two radiologists and inter-reader agreement was κ = 0.37.

“Our study shows that the normal CZ demonstrates either type one or type two enhancement time curves on DCE-MRI, which can be potentially used to differentiate the CZ from PCa,” wrote the authors. “Given the absence of type three enhancement time curves in the normal CZ in our study, our findings suggest that qualitative DCE-MRI analysis can be a valuable tool in distinguishing between normal CZ and PCa.”