Increasing the accuracy of volume and ADC delineation for heterogeneous tumor on diffusion-weighted MRI: Correlation with PET/CT

Nan Jie Gong, Chun Sing Wong, Yiu Ching Chu, Hua Guo, Bingsheng Huang, Queenie Chan

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Purpose To improve the accuracy of volume and apparent diffusion coefficient (ADC) measurements in diffusion-weighted magnetic resonance imaging (MRI), we proposed a method based on thresholding both the b0 images and the ADC maps. Methods and Materials In 21 heterogeneous lesions from patients with metastatic gastrointestinal stromal tumors (GIST), gross lesion were manually contoured, and corresponding volumes and ADCs were denoted as gross tumor volume (GTV) and gross ADC (ADCg), respectively. Using a k-means clustering algorithm, the probable high-cellularity tumor tissues were selected based on b0 images and ADC maps. ADC and volume of the tissues selected using the proposed method were denoted as thresholded ADC (ADCthr) and high-cellularity tumor volume (HCTV), respectively. The metabolic tumor volume (MTV) in positron emission tomography (PET)/computed tomography (CT) was measured using 40% maximum standard uptake value (SUVmax) as the lower threshold, and corresponding mean SUV (SUVmean) was also measured. Results HCTV had excellent concordance with MTV according to Pearson's correlation (r=0.984, P<.001) and linear regression (slope = 1.085, intercept = -4.731). In contrast, GTV overestimated the volume and differed significantly from MTV (P=.005). ADCthr correlated significantly and strongly with SUVmean (r=-0.807, P<.001) and SUVmax (r=-0.843, P<.001); both were stronger than those of ADCg. Conclusions The proposed lesion-adaptive semiautomatic method can help segment high-cellularity tissues that match hypermetabolic tissues in PET/CT and enables more accurate volume and ADC delineation on diffusion-weighted MR images of GIST.

Original languageEnglish
Pages (from-to)407-413
Number of pages7
JournalInternational Journal of Radiation Oncology Biology Physics
Volume87
Issue number2
DOIs
StatePublished - 1 Oct 2013
Externally publishedYes

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