Rationale and Objectives
Evaluate qualitative dynamic contrast-enhanced magnetic resonance imaging (MRI) characteristics of normal central zone based on recently described central zone MRI features.
Materials and Methods
Institutional review board–approved, Health Insurance Portability and Accountability Act compliant study, 59 patients with prostate cancer, histopathology proven to not involve central zone or prostate base, underwent endorectal MRI before prostatectomy. Two readers independently reviewed T2-weighted images and apparent diffusion coefficient (ADC) maps identifying normal central zone based on low signal intensity and location. Next, two readers drew bilateral central zone regions of interest on dynamic contrast-enhanced magnetic resonance images in consensus and independently recorded enhancement curve types as type 1 (progressive), type 2 (plateau), and type 3 (wash-out). Identification rates of normal central zone and enhancement curve type were recorded and compared for each reviewer. The institutional review board waiver was approved and granted 05/2010.
Results
Central zone identified in 92%–93% of patients on T2-weighted images and 78%–88% on ADC maps without significant difference between identification rates ( P = .63 and P = .15 and inter-reader agreement (κ) is 0.64 and 0.29, for T2-weighted images and ADC maps, respectively). All central zones were rated either curve type 1 or curve type 2 by both radiologists. No statistically significant difference between the two radiologists ( P = .19) and inter-reader agreement was κ = 0.37.
Conclusions
Normal central zone demonstrates either type 1 (progressive) or type 2 (plateau) enhancement curves on dynamic contrast-enhanced MRI that can be potentially useful to differentiate central zone from prostate cancer that classically demonstrates a type 3 (wash-out) enhancement curve.
McNeal’s model of prostate anatomy is now over a quarter century old and widely accepted by pathologists, urologists, and radiologists who are involved in the management of prostate cancer (PCa) . According to McNeal, the prostate can be divided into three glandular zones (peripheral zone [PZ], transition zone [TZ], and central zone [CZ]) and one nonglandular zone (anterior fibromuscular stroma) based on histology, anatomic location, and embryologic features . TZ refers to the bilateral regions in the mid to base of the gland, which form two bulges on either side of the urethra that extend superiorly, anteriorly, and laterally from the verumontanum. The CZ is a flattened conical structure located posterior to the TZ and surrounds the ejaculatory ducts ( Fig 1 ). Embryologically, CZ derives from the Wolffian duct whereas TZ is a derivative of the urogenital sinus .
Open full size image
Figure 1
Coronal prostate diagram adapted from McNeal’s model of prostate anatomy demonstrating the conical-shaped CZ extending from the base of the prostate to the level of the verumontanum. CZ, central zone; DU, distal urethra; E, ejaculatory duct; PZ, peripheral zone; V = verumontanum.
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Materials and methods
Study Patients
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MRI Protocols
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MRI Analysis
Analysis of T2-weighted images and ADC maps
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DCE-MRI Analysis
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Statistical Analysis
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Results
Identification of Normal CZ on T2-weighted Images and ADC Maps
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Table 1
CZ Identification Rates on T2-weighted Images and on ADC Maps
Modality Radiologist CZ Detection Rate (%) [95% Confidence Interval] T2-weighted A 93 (55/59) [84%–98%] B 92 (54/59) [81%–97%] ADC map A 88 (52/59) [77%–95%] B 78 (46/59) [65%–88%]
ADC, apparent diffusion coefficient; CZ, central zone.
Table 2
Agreement in CZ Identification on T2-weighted Images between the Two Radiologists
Radiologist B Identified Not Total A Identified 53 2 55 Not 1 3 4 Total 54 5 59
CZ, central zone.
Table 3
Agreement in CZ Identification on ADC Maps between the Two Radiologists
Radiologist B Identified Not Total A Identified 43 9 52 Not 3 4 7 Total 46 13 59
ADC, apparent diffusion coefficient; CZ, central zone.
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DCE-MRI Analysis
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Table 4
Agreement in DCE Time Curve Analysis between the Two Radiologists
Radiologist B Type 1 Type 2 Type 3 Total A Type 1 10 14 0 24 Type 2 7 73 0 80 Type 3 0 0 0 0 Total 17 87 0 104
DCE, dynamic contrast-enhanced.
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Discussion
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Appendix
GE Healthcare Unit Protocol
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Philips Healthcare Unit Protocol
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