Diagnostic Benefit of High b-Value Computed Diffusion-Weighted Imaging in Patients with Hepatic Metastasis.

Aaron Schindler,Daniel Seehofer,Hans Surup,Hans-Jonas Meyer,Maxime Ablefoni,Constantin Ehrengut,Timm Denecke

doi:10.3390/jcm10225289

Abstract

Diffusion-weighted imaging (DWI) has rapidly become an essential tool for the detection of malignant liver lesions. The aim of this study was to investigate the usefulness of high b-value computed DWI (c-DWI) in comparison to standard DWI in patients with hepatic metastases. In total, 92 patients with histopathologic confirmed primary tumors with hepatic metastasis were retrospectively analyzed by two readers. DWI was obtained with b-values of 50, 400 and 800 or 1000 s/mm2 on a 1.5 T magnetic resonance imaging (MRI) scanner. C-DWI was calculated with a monoexponential model with high b-values of 1000, 2000, 3000, 4000 and 5000 s/mm2. All c-DWI images with high b-values were compared to the acquired DWI sequence at a b-value of 800 or 1000 s/mm2 in terms of volume, lesion detectability and image quality. In the group of a b-value of 800 from a b-value of 2000 s/mm2, hepatic lesion sizes were significantly smaller than on acquired DWI (metastases lesion sizes b = 800 vs. b 2000 s/mm2: mean 25 cm3 (range 10–60 cm3) vs. mean 17.5 cm3 (range 5–35 cm3), p < 0.01). In the second group at a high b-value of 1500 s/mm2, liver metastases were larger than on c-DWI at higher b-values (b = 1500 vs. b 2000 s/mm2, mean 10 cm3 (range 4–24 cm3) vs. mean 9 cm3 (range 5–19 cm3), p < 0.01). In both groups, there was a clear reduction in lesion detectability at b = 2000 s/mm2, with hepatic metastases being less visible compared to c-DWI images at b = 1500 s/mm2 in at least 80% of all patients. Image quality dropped significantly starting from c-DWI at b = 3000 s/mm2. In both groups, almost all high b-values images at b = 4000 s/mm2 and 5000 s/mm2 were not diagnostic due to poor image quality. High c-DWI b-values up to b = 1500 s/mm2 offer comparable detectability for hepatic metastases compared to standard DWI. Higher b-value images over 2000 s/mm2 lead to a noticeable reduction in imaging quality, which could hamper diagnosis.

Highlights

The most common malignant liver lesions are hepatic metastases, resulting in the most common indication for liver imaging [1]
High c-Diffusion-weighted imaging (DWI) b-values up to b = 1500 s/mm2 offer comparable detectability for hepatic metastases compared to standard DWI
The present study investigated the possible benefit of high b-values computed DWI (c-DWI) in the diagnosis of hepatic metastasis

Summary

Introduction

The most common malignant liver lesions are hepatic metastases, resulting in the most common indication for liver imaging [1]. The most sensitive MRI sequences for metastasis detection are diffusion-weighted imaging (DWI) and hepatobiliary phase (HP) images after intravenous application from a liver-specific contrast agent. Indicative features such as peripheral ring enhancement, diffusion restriction, and hypointensity on HP are typically seen in hepatic metastases [4,5,6]. Malignant tumors have higher cellularity, with resulting diffusion restriction detected by DWI [3,10]. DWI plays an essential role in tumor detection and characterization based on the high contrast between the lesion and surrounding tissue [11]. DWI can be prone to image artifacts such as blurring or ghosting artifacts [5]

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Conclusion