Added value of diffusion‐weighted imaging in the MRI assessment of perilesional tumor recurrence after chemoembolization of hepatocellular carcinomas

Abstract

Purpose: To investigate the additional value of diffusionweighted imaging (DWI) in the MRI assessment of perilesionally recurrent hepatocellular carcinomas (HCCs) after transcatheter arterial chemoembolization (TACE). Materials and Methods:For gadopentetate dimeglumineenhanced multiphasic dynamic images with precontrast T1-and T2-weighted images of 23 patients treated with TACE, two radiologists independently sorted the confidence levels for the presence of a viable tumor in the vicinity of the treated lesions into five grades. In another session, images from DWI (b factor ϭ 50, 400, and 800 s/mm 2 ) were added to the previously reviewed images and the same radiologists sorted the confidence levels.Results: A total of 26 lesions (0.7-3.5 cm) from 16 patients were confirmed to be perilesional recurrences of HCC. The area under the receiver operating characteristic curve (A z ) for the second interpretation session (0.826) was not significantly different (P ϭ 0.299) from that of the first session (0.859). The overall sensitivity was increased from 85% to 92%, but the specificity decreased from 65% to 50% after adding DWI. Conclusion:The addition of DWI has the potential to improve sensitivity, but not the overall diagnostic accuracy, in the assessment of perilesional recurrence of HCCs after chemoembolization. DUE TO THE LIMITED curative surgical indications aside from liver transplantation, transcatheter arterial chemoembolization (TACE) is widely performed for the curative or palliative treatment of hepatocellular carcinoma (HCC) in a cirrhotic liver. In the majority of cases, however, the tumors are not completely necrotized and the incidence of recurrence after TACE is still high (1-3). To prevent further complications and advanced stages of the disease with an unfavorable prognosis, it is critical that follow-up imaging studies focus on early recognition of intralesional viable tumors or localized recurrences.Dynamic CT with a precontrast scan and multiphasic post-contrast-enhanced imaging is generally used as a follow-up imaging modality of choice after TACE, based on the radio-opacity of the iodized oil that selectively accumulates in the tumor. However, due to partial volume or beam-hardening artifact, the high attenuation density of the iodized oil can limit the accuracy of CT in depicting a small viable tumor portion in or adjacent to the lesion (4 -6). To avoid the interference of accumulated iodized oil, Doppler ultrasonography or dynamic MRI has been used as an alternative to dynamic CT (7-11); however, inherent ultrasonic attenuation or T1-weighted hyperintensity of hemorrhagic-necrotic changes still affects the correct interpretation of contrast-enhanced viable tumor tissue.Meanwhile, diffusion-weighted imaging (DWI) has been applied to body MRI including liver imaging for the assessment of focal lesions according to restricted water diffusion and low apparent diffusion coefficient (ADC) values for malignant lesions, including HCCs. There have been several studies on the decrease of signal intensity...

Unresectable Hepatocellular Carcinoma: MR Imaging after Intraarterial Therapy. Part II. Response Stratification Using Volumetric Functional Criteria after Intraarterial Therapy

“…Specifically, an increase in ADC values was proposed as a noninvasive measurement of tumor necrosis after treatment (14,35,36). The tumor ADC value may substantially change as early as 1-2 weeks after therapy (37).…”

APASL and AASLD Consensus Guidelines on Imaging Diagnosis of Hepatocellular Carcinoma: A Review

“…It improves MR detection of HCCs, particularly in lesions smaller than 2 cm [85], with sensitivities of 84–98% compared to 76–85% for multiphasic MRI alone [86–88]. Potentially, objective measurement of the apparent diffusion coefficient (ADC) may allow for distinction between the different tumour grades [89, 90].…”

“…It can be combined with SPIO-enhanced MRI, raising sensitivity from 66% to 70%, while maintaining high specificity of 98% [91]. DW MRI also shows potential for assessment of treatment response to local ablative therapies [88, 92]. Its role in the diagnostic algorithm is not certain at this point, although, given the promising results and its ease of implementation in routine clinical practice (due to fast acquisition times, no needs for additional hardware and ease of interpretation), incorporation into future guidelines is anticipated.…”

Prognostication and response assessment in liver and pancreatic tumors: The new imaging

“…Mannelli et al [91] did not report differences between conventional MRI sequences and DWI for the assessment of post-TACE necrosis, although enhancement decrease on MRI subtraction images was more significantly correlated with pathological findings than ADC increase. Although quantitative analysis of diffusion restriction appears to be of value in assessing response to TACE, visual analysis seems to be less accurate: Goshima et al [92] reported that DW images were significantly less sensitive than contrast-enhanced images in detecting residual/recurrent tumor after TACE, and Yu et al [93] reported that the addition of DW images to contrastenhanced images reduced specificity and diagnostic accuracy in detecting perilesional recurrence. Probably, the presence of treatment-induced granulation tissue is the cause of DWI false positives.…”