Apparent diffusion coefficient normalization of normal liver

Abstract

Apparent diffusion coefficient (ADC) measurement in diffusion-weighted imaging (DWI) has been reported to be a helpful biomarker for detection and characterization of lesion. In view of the importance of ADC measurement reproducibility, the aim of this study was to probe the variability of the healthy hepatic ADC values measured at 3 MR scanners from different vendors and with different field strengths, and to investigate the reproducibility of normalized ADC (nADC) value with the spleen as the reference organ. Thirty enrolled healthy volunteers received DWI with GE 1.5T, Siemens 1.5T, and Philips 3.0T magnetic resonance (MR) systems on liver and spleen (session 1) and were imaged again after 10 to 14 days using only GE 1.5T MR and Philips 3.0T MR systems (session 2). Interscan agreement and reproducibility of ADC measurements of liver and the calculated nADC values (ADCliver/ADCspleen) were statistically evaluated between 2 sessions. In session 1, ADC and nADC values of liver were evaluated for the scanner-related variability by 2-way analysis of variance and intraclass correlation coefficients (ICCs). Coefficients of variation (CVs) of ADCs and nADCs of liver were calculated for both 1.5 and 3.0-T MR system. Interscan agreement and reproducibility of ADC measurements of liver and related nADCs between 2 sessions were found to be satisfactory with ICC values of 0.773 to 0.905. In session 1, the liver nADCs obtained from different scanners were consistent (P = 0.112) without any significant difference in multiple comparison (P = 0.117 to >0.99) by using 2-way analysis of variance with post-hoc analysis of Bonferroni method, although the liver ADCs varied significantly (P < 0.001). nADCs measured by 3 scanners were in good interscanner agreements with ICCs of 0.685 to 0.776. The mean CV of nADCs of both 1.5T MR scanners (9.6%) was similar to that of 3.0T MR scanner (8.9%). ADCs measured at 3 MR scanners with different field strengths and vendors could not be compared directly. Normalization of ADCs, however, may provide better reproducibility by overcoming these potential issues.

Reproducibility of intravoxel incoherent motion of liver on a 3.0T scanner: free-breathing and respiratory-triggered sequences acquired with different numbers of excitations

“…Moreover, a lack of standardisation of IVIM technique and significant variance in calculated parameters among studies thus far precludes application of this method for routine MR liver imaging for application as an eligible biomarker. In addition, IVIM-derived parameters, similarly to ADC values, are possibly both vendor and field strength dependent (1.5T vs. 3.0T) [19,20]. Among many factors that may influence DWI calculations are echo time, gradient amplitude, and separation of diffusion gradient [20].…”

“…In addition, IVIM-derived parameters, similarly to ADC values, are possibly both vendor and field strength dependent (1.5T vs. 3.0T) [19,20]. Among many factors that may influence DWI calculations are echo time, gradient amplitude, and separation of diffusion gradient [20]. Accurate calculation of IVIM parameters from a 3.0T MR scanner requires high SNR for all acquired b values.…”

Diffusion weighted MRI as an early predictor of tumor response to hypofractionated stereotactic boost for prostate cancer

“… 25 the liver nADCs obtained from three different scanners (1.5 and 3 T) were consistent although the liver ADCs varied significantly (p < 0.001). ADC measured at different scanners with different field strengths could not be compared directly but nADC may provide better reproducibility by overcoming these potential issues 25 . The influence of delineation deviations on nADC results are beyond the scope of this study.…”

Objective value on Apparent diffusion coefficient (ADC) map to categorize the intensity of diffusion-weighted imaging (DWI) restriction for prostate cancer detection on multiparametric prostate MRI

“…There are some factors described that can affect the ADC measurements, such as b values, respiration conditions, field strength, vendor and other technical parameters ( 21 ). On the other hand, Sadinski et al demonstrated, comparing ADC maps between two consecutive scans of same patient, that the reproducibility of ADC measurements in prostate is reasonable, suggesting that quantitative values obtained in DWI-MRI of prostate cancer are reproducible ( 22 ).…”

“…Our study found similar values on ADC map for positive and negative prostate cancer biopsies (0.81 mm2 / sec and 1.08 mm2 / sec for reader 1, and 0.84 mm2 / sec and 1.09 mm2 / sec for reader 2, respectively), compared to literature, that ranges from 0.74 mm2 / sec (SD 0.15) to 0.80 mm 2 / sec (SD 0.25) for positive prostate cancer biopsies and 1.35 mm 2 / sec (SD 0.31) to 1.48 mm2 / sec (SD 0.29) for negative biopsies ( 18 , 19 ), corroborating that ADC map value can be reproducible. Also, it has been already shown that using a parameter to normalize the ADC measurement (as the normal parenchyma or muscle), the ADC value can be reproducible among different scanners ( 21 ).…”