Image quality and diagnostic performance of free-breathing diffusion-weighted imaging for hepatocellular carcinoma

Abstract

AIMTo retrospectively evaluate the diagnostic performance of free-breathing diffusion-weighted imaging (FB-DWI) with modified imaging parameter settings for detecting hepatocellular carcinomas (HCCs).METHODSFifty-one patients at risk for HCC were scanned with both FB-DWI and respiratory-triggered DWI with the navigator echo respiratory-triggering technique (RT-DWI). Qualitatively, the sharpness of the liver contour, the image noise and the chemical shift artifacts on each DWI with b-values of 1000 s/mm2 were independently evaluated by three radiologists using 4-point scoring. We compared the image quality scores of each observer between the two DWI methods, using the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma and lesion-to-nonlesion contrast-to-noise ratios (CNRs) after measuring the signal intensity on each DWI with a b-factor of 1000 s/mm2. The average SNRs and CNRs between the two DWI methods were compared by the paired t-test. The detectability of HCC on each DWI was also analyzed by three radiologists. The detectability provided by the two DWI methods was compared using McNemar’s test.RESULTSFor all observers, the averaged image quality scores of FB-DWI were: Sharpness of the liver contour [observer (Obs)-1, 3.08 ± 0.81; Obs-2, 2.98 ± 0.73; Obs-3, 3.54 ± 0.75], those of the distortion (Obs-1, 2.94 ± 0.50; Obs-2, 2.71 ± 0.70; Obs-3, 3.27 ± 0.53), and the chemical shift artifacts (Obs-1, 3.38 ± 0.60; Obs-2, 3.15 ± 1.07; Obs-3, 3.21 ± 0.85). The averaged image quality scores of RT-DWI were: Sharpness of the liver contour (Obs-1, 2.33 ± 0.65; Obs-2, 2.37 ± 0.74; Obs-3, 2.75 ± 0.81), distortion (Obs-1, 2.81 ± 0.56; Obs-2, 2.25 ± 0.74; Obs-3, 2.96 ± 0.71), and the chemical shift artifacts (Obs-1, 2.92 ± 0.59; Obs-2, 2.21 ± 0.85; Obs-3, 2.77 ± 1.08). All image quality scores of FB-DWI were significantly higher than those of RT-DWI (P < 0.05). The average SNR of the normal liver parenchyma by FB-DWI (11.0 ± 4.8) was not significantly different from that shown by RT-DWI (11.0 ± 5.0); nor were the lesion-to-nonlesion CNRs significantly different (FB-DWI, 21.4 ± 17.7; RT-DWI, 20.1 ± 15.1). For all three observers, the detectability of FB-DWI (Obs-1, 43.6%; Obs-2, 53.6%; and Obs-3, 45.0%) was significantly higher than that of RT-DWI (Obs-1, 29.1%; Obs-2, 43.6%; and Obs-3, 34.5%) (P < 0.05).CONCLUSIONFB-DWI showed better image quality and higher detectability of HCC compared to RT-DWI, without significantly reducing the SNRs of the liver parenchyma and lesion-to-nonlesion CNRs.

Recent advances in non-invasive magnetic resonance imaging assessment of hepatocellular carcinoma

“…Although several DW imaging sequences can be applied to evaluate the liver, the single shot spin-echo (SE) echo-planar technique is the most frequently used in combination with fat suppression. Recent studies[ 68 ] compared free breathing (FB) vs respiratory triggered (RT) DWI for detecting HCC, using a 3 T scanner, a 32-channel torso-cardiac phased-array coil, and dual-source parallel radiofrequency excitation and transmission technology. They concluded that FB-DWI provided better image quality and showed higher detectability of HCCs in patients with chronic liver disease compared to RT-DWI, without significantly reducing the SNR of the normal liver parenchyma or the lesion-to-non lesion CNR.…”

Modulating Diffusion-Weighted Magnetic Resonance Imaging for Screening in Oncologic Tertiary Prevention

“…Regarding the upper abdominal region, breathing is considered to be an influencing factor, but Takayama et al 35,36 could show good results by the use of free-breathing DWI compared with respiratory-triggered DWI. Consequently, both s-DWI and opt-DWI were performed under free-breathing conditions, leading to good image quality in both sequences.…”

A Recent Short Review in Non-Invasive Magnetic Resonance Imaging on Assessment of HCC Stages: MRI Findings and Pathological Diagnosis

“…The same thing happens when the tissue has many small cells within the lesion, and HCC is known to have many small cells compared with normal hepatocytes. Therefore, the cells number in HCC is higher than the normal liver cells [15] . Thus, the diffusion of water is restricted, and this could be indicated by the low value of Apparent diffusion coefficient (ADC) [16] which is considered as post-processing of DWI sequences [15] .…”

“…Therefore, the cells number in HCC is higher than the normal liver cells [15] . Thus, the diffusion of water is restricted, and this could be indicated by the low value of Apparent diffusion coefficient (ADC) [16] which is considered as post-processing of DWI sequences [15] . Therefore, the diffusion restriction indicates the signal intensity of a tumour which is higher compared with the surrounding parenchyma, and the b-value (expressed in seconds per millimeter square) DW MR images would be high [17] , Also, the restriction of diffusion in malignant tumours is higher than the benign lesions [18] .…”

“…The apparent diffusion coefficient (ADC) measurement helps to provide additional information about morphological characteristics, analysing the structure, quantitative index of diffusion characteristics, and tissue components [18,19] . And can be calculated by using two different values of b-value (one value is low, and the other is intermediate or high) [15] . The sensitivity and specificity of ADC are reached…”