Hepatocellular Carcinoma and Diffusion-Weighted MRI: Detection and Evaluation of Treatment Response

Abstract

Differentiating between cancerous tissue and healthy liver parenchyma could represent a challenge with the only conventional Magnetic Resonance (MR) imaging. Diffusion weighted imaging (DWI) exploits different tissue characteristics to conventional Magnetic Resonance Imaging (MRI) sequences that enhance hepatocellular carcinoma (HCC) detection, characterization, and post-treatment evaluation. Detection of HCC is improved by DWI, infact this technology increases conspicuity of lesions that might otherwise not be identified due to obscuration by adjacent vessels or due to low contrast between the lesion and background liver. It is important to remember that DWI combined with contrast-enhanced MRI has higher sensitivity than DWI alone, and that some patients are not eligible for use of contrast on CT and MRI; in these patients DWI has a prominent role. MRI has advanced beyond structural anatomic imaging to now showing pathophysiologic processes. DWI is a promising way to characterize lesions utilizing the inherent contrast within the liver and has the benefit of not requiring contrast injection. DWI improves detection and characterization of HCC. Proposed clinical uses for DWI include: assessing prognosis, predicting response, monitoring response to therapy, and distinguishing tumor recurrence from treatment effect. Ideally, DWI will help risk stratify patients and will participate in prognostic modeling.

State of the art in magnetic resonance imaging of hepatocellular carcinoma

“…Studies investigating the utility of DWI have demonstrated promising results for assessing prognosis, predicting response, distinguishing tumor from treatment effect, and monitoring response to therapy in patients with HCC. 18 , 19 , 20 , 21 , 22 ,…”

“…Regenerative nodules may present accumulation of iron which results in low signal intensity on T1-and T2-weighted imaging. 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ,…”

“… 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , cHCC-CC may appear hypointense on T1WI and iso to hyperintense on T2WI with or without central hypointense focus, which represents a central cholangiocarcinoma or fibrotic component. 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , On dynamic imaging, early ring enhancement with centripetal progression or heterogeneous early enhancement with partial washout are possible p...…”

Diffusion-weighted imaging of hepatocellular carcinoma before and after transarterial chemoembolization: role in survival prediction and response evaluation

“…The diffusion restriction, which can be quantified into an apparent diffusion coefficient (ADC), is therefore a way of non-invasively measuring the cellularity of (tumor) tissue. Prior studies have found an inverse correlation between ADC value and histological tumor grade and microvascular invasion [8][9][10][11]. Kamel et al first demonstrated the feasibility of DWI for response assessment after TACE by showing that an increased tumoral ADC at 4-6 weeks after TACE corresponded to radiological and histological response [12,13].…”

MR with Gd-EOB-DTPA in assessment of liver nodules in cirrhotic patients

“…Moreover, OATP8 expression level reduces prior to complete neoangiogenesis[ 12 ] and the use of hepatospecific contrast media in MRI is considered a “new” HCC diagnostic tools that allows either to increase sensitivities for detection of HCC of all sizes[ 13 ] or would make it possible to identify preneoplastic lesions, such as HGDNs[ 14 ]. Furthermore, MRI offers additional imaging sequences that can be helpful in nodule characterization, including T2-weighted imaging (T2-WI) and diffusion-weighted imaging (DWI), which provides information on cellularity and has shown additional value to gadolinium-enhanced MRI by increasing the detection rate of HCC[ 15 ]. However, precise differentiation of preneoplastic lesions remain uncertain to date.…”