Evaluation of the normal-to-diseased apparent diffusion coefficient ratio as an indicator of prostate cancer aggressiveness

Abstract

BackgroundWe tested the feasibility of a simple method for assessment of prostate cancer (PCa) aggressiveness using diffusion-weighted magnetic resonance imaging (MRI) to calculate apparent diffusion coefficient (ADC) ratios between prostate cancer and healthy prostatic tissue.MethodsThe requirement for institutional review board approval was waived. A set of 20 standardized core transperineal saturation biopsy specimens served as the reference standard for placement of regions of interest on ADC maps in tumorous and normal prostatic tissue of 22 men with PCa (median Gleason score: 7; range, 6–9). A total of 128 positive sectors were included for evaluation. Two diagnostic ratios were computed between tumor ADCs and normal sector ADCs: the ADC peripheral ratio (the ratio between tumor ADC and normal peripheral zone tissue, ADC-PR), and the ADC central ratio (the ratio between tumor ADC and normal central zone tissue, ADC-CR). The performance of the two ratios in detecting high-risk tumor foci (Gleason 8 and 9) was assessed using the area under the receiver operating characteristic curve (AUC).ResultsBoth ADC ratios presented significantly lower values in high-risk tumors (0.48 ± 0.13 for ADC-CR and 0.40 ± 0.09 for ADC-PR) compared with low-risk tumors (0.66 ± 0.17 for ADC-CR and 0.54 ± 0.09 for ADC-PR) (p < 0.001) and had better diagnostic performance (ADC-CR AUC = 0.77, sensitivity = 82.2%, specificity = 66.7% and ADC-PR AUC = 0.90, sensitivity = 93.7%, specificity = 80%) than stand-alone tumor ADCs (AUC of 0.75, sensitivity = 72.7%, specificity = 70.6%) for identifying high-risk lesions.ConclusionsThe ADC ratio as an intrapatient-normalized diagnostic tool may be better in detecting high-grade lesions compared with analysis based on tumor ADCs alone, and may reduce the rate of biopsies.

Comparison of PI-RADS 2, ADC histogram-derived parameters, and their combination for the diagnosis of peripheral zone prostate cancer

“…In PI-RADS V2, diffusion-weighted MRI (DWI) is the sequence that characterizes most lesions located in the peripheral zone, and it is scored based on the subjective assessment of high b-value images and apparent diffusion coefficient (ADC) map. Yet, ADC values have been reported to demonstrate an inverse correlation with Gleason scores [12][13][14][15]. While ADC values are most commonly assessed as the mean value on a single slice [12][13][14]16], several parameters, including the median [13,16], 10th [12][13][14]16], 25th [13], and 75th [16] histogram-derived percentiles of ADC, as well as the normalized ratio [15], have also been used to predict Gleason scores.…”

“…While ADC values are most commonly assessed as the mean value on a single slice [12][13][14]16], several parameters, including the median [13,16], 10th [12][13][14]16], 25th [13], and 75th [16] histogram-derived percentiles of ADC, as well as the normalized ratio [15], have also been used to predict Gleason scores. More elaborate tools, such as volumetric analysis [13] and mathematical models [12][13][14][15][16][17][18], have also been tested to predict tumor aggressiveness. While some of these studies have investigated the use of ADC values in the context of of the first version of PI-RADS, little is known about how these may improve PI-RADS V2.…”

Multiparametric MRI of the prostate: diagnostic performance and interreader agreement of two scoring systems

“…As shown in [19][20][21][22][23][24] Although not part of the DWI scoring criteria of PI-RADS v. 2, the use of an ADC threshold of 750-900 3 10 26 mm 2 s 21 is described in its publication as a possible adjunct feature that correlates with clinically significant cancers, 16 and ADC value cut-off utilized by the UCSF scale is within this range. The mean ADC value of a lesion was measured on the ADC map, utilizing a region of interest that was drawn to occupy approximately 75% of its diameter.…”

“…The scanning protocol included T 2 weighted imaging (T2WI), DWI and DCE MRI. DWI was acquired with b-values of 0 and 1000 s 21 mm 22 and with an inline reconstruction of apparent diffusion coefficient (ADC) map. DCE MRI of the prostate was performed following administration of 0.1 mmol of gadopentetate dimeglumine (Magnevist®; Bayer HealthCare Pharmaceuticals, Montville, NJ) per kilogram of body weight followed by a 20 ml saline flush at a rate of 3 ml s…”

Diffusion Weighted Magnetic Resonance Imaging for the Classification of Focal Liver Lesions as Benign or Malignant

“…As far as we know, our paper is the first to use the ADC ratio for discriminating between benign and malignant lesions in liver pathology. Previously, the ADC ratio was proved to be a good diagnostic tool for malignancy in prostatic cancers [38]. On the other hand, the ADC value is less prone to variations between readers.…”