Respiratory gated diffusion-weighted imaging of the liver: value of apparent diffusion coefficient measurements in the differentiation between most commonly encountered benign and malignant focal liver lesions

Abstract

The purpose of this study was to measure apparent diffusion coefficient values of normal liver parenchyma and focal liver lesions utilizing a respiratory gated diffusion sequence with multiple b-values and to investigate whether apparent diffusion coefficient (ADC) measurements may be utilized to characterize and differentiate between malignant and benign focal hepatic lesions. Thirty-eight consecutive patients underwent MRI of the liver including diffusion-weighted imaging (DWI). A single-shot echo planar imaging sequence was applied in coronal orientation with multiple b-values (0, 50, 500, 1,000 s/mm2) and respiratory gating. ADC values were recorded on corresponding maps utilizing region of interest measurements in patients with benign (group A), malignant (group B) focal lesions and liver parenchyma (group C). Statistical analysis was applied to check whether differences in mean ADC values were significant (p<0.05). No focal lesions were detected in 11 patients, with a mean ADC value (CI 95%) of liver parenchyma 1.25x10(-3) mm2/s (1.21x10(-3) mm2/s-1.29x10(-3) mm2/s). Differences in mean ADC of liver parenchyma between group A and B were not significant (p=0.054, 1.30x10(-3) mm2/s and 1.31x10(-3) mm2/s, respectively). Mean ADC value (95% CI) of 22 benign lesions found in 18 patients was 2.55x10(-3) mm2/s (2.35x10(-3) mm2/s-2.74x10(-3) mm2/s), while the mean ADC value (95% CI) of 16 malignant lesions recorded in 9 patients was 1.04x10(-3) mm2/s (0.9x10(-3) mm2/s-1.17x10(-3) mm2/s). The difference between mean ADC values of benign and malignant focal lesions was statistically significant (p<0.0001). Respiratory gated diffusion-weighted imaging in the liver is technically feasible. Apparent diffusion coefficient measurements can be useful in differentiating malignant from benign focal liver lesions.

Diffusion‐weighted imaging of the liver: Comparison of navigator triggered and breathhold acquisitions

“…Gourtsoyianni et al (29) assessed the accuracy of ADC obtained with non navigator echo respiratory triggered SS EPI DWI sequence (n ϭ 38) for characterization of liver lesions, and found sensitivity and specificity of 100% for diagnosis of malignancy using lesion ADC Ͻ 1.26 ϫ 10 Ϫ3 mm 2 /s, similar to our reported sensitivity and specificity. Bruegel et al (15,16) used the same MR system used in our study and a similar PACE DWI sequence to detect and characterize liver lesions.…”

“…There are several recent reports on the use of respiratory triggered acquisitions for liver DWI (15,16,[28][29][30][31]. However, only two studies have specifically compared different diffusion acquisition schemes for liver imaging (28,30).…”

“…Respiratory triggering is another method that can be proposed to improve image quality of DWI. Respiratory triggering is a technique that attempts to avoid motion artifacts prospectively by using respiratory signals to synchronize the image acquisition with the patient's breathing cycle and by acquiring the imaging data during the relative quite end expiration phase (28,29,38,(55)(56)(57)(58)(59).…”

“…SS EPI sequences are very fast, however, suffer from limited image quality, mostly related to limited signal to noise ratio (SNR) especially at higher b-values, and limited spatial resolution, which constitute an obstacle for its widespread use in clinical practice. Techniques such as parallel imaging (25,26) and pulse triggering (27) have been proposed to improve SS EPI image quality and precision of ADC measurement.There are several recent reports on the use of respiratory triggered acquisitions for liver DWI (15,16,[28][29][30][31]. However, only two studies have specifically compared different diffusion acquisition schemes for liver imaging (28,30).…”

Interobserver and intraobserver variability of the apparent diffusion coefficient in treated malignant hepatic lesions on a 3.0T machine: Measurements in the whole lesion versus in the area with the most restricted diffusion

“…It has been established that focal lesions of the liver can be evaluated qualitatively by means of DWI and the apparent diffusion coefficient (ADC). For example, a very cellular lesion like a hepatocellular carcinoma will demonstrate restricted diffusion (5,6), as the swollen tumoral cells will keep water molecules in the intracellular compartment (7).…”