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The aim of the study was to assess the role of diffusion-weighted imaging (DWI) to evaluate treatment response in patients with liver metastases of colorectal cancer.

Background: To compare Gd-ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and 99mTc-labelled mebrofenin hepatobiliary scintigraphy (HBS) as imaging-based liver function tests after unilateral radioembolisation (RE) in patients with primary or secondary liver malignancies. Methods: Twenty-three patients with primary or secondary liver malignancies who underwent Gd-EOB-DTPA-enhanced MRI within a prospective study (REVoluTion) were evaluated. REVoluTion was a prospective open-label, non-randomised, therapy-optimising study of patients undergoing right-sided or sequential RE for contralateral liver hypertrophy at a single centre in Germany. MRI and hepatobiliary scintigraphy were performed before RE (baseline) and 6 weeks after (follow-up). This exploratory subanalysis compared liver enhancement on hepatobiliary phase MRI normalised to the spleen (liver-to-spleen ratio (LSR)) and the muscle (liver-to-muscle ratio (LMR)) with mebrofenin uptake on HBS for the total liver (TL) and separately for the right (RLL) and left liver lobe (LLL). Results: Mebrofenin uptake at baseline and follow-up each correlated significantly with LSR and LMR on MRI for TL (≤ 0.013) and RLL (≤ 0.049). Regarding the LLL, mebrofenin uptake correlated significantly with LMR (baseline, p = 0.013; follow-up, p = 0.004), whereas with LSR, a borderline significant correlation was only seen at follow-up (p = 0.051; p = 0.046). Conclusion: LSRs and LMR correlate with mebrofenin uptake in HBS. This study indicates that Gd-EOB-DTPA-enhanced MRI and 99mTc-labelled mebrofenin HBS may equally be used to assess an increase in contralateral liver lobe function after right-sided RE. Relevance statement: MRI may be a convenient and reliable method for assessing the future liver remnant facilitating treatment planning and monitoring of patients after RE-induced hypertrophy induction. Key points: • Both MRI and HBS can assess liver function after RE. • Liver enhancement on MRI correlates with mebrofenin uptake on HBS. • MRI might be a convenient alternative for estimating future liver remnants after hypertrophy induction. [ABSTRACT FROM AUTHOR]

Background: High-dose-rate computed tomography (CT)-guided brachytherapy (HDR-BT) has shown promising results in patients with hepatocellular carcinoma (HCC). While growing evidence shows clear limitations of mRECIST, diffusion-weighted imaging (DWI) has relevant potential in improving the response assessment. Purpose: To assess whether DWI allows evaluation of short- and long-term tumor response in patients with HCC after HDR-BT. Material and Methods: A total of 22 patients with 11 non-responding HCCs (NR-HCC; local tumor recurrence within two years) and 24 responding HCCs (R-HCC; follow-up at least two years) were included in this retrospective bi-center study. HCCs were treated with HDR-BT and patients underwent pre- and post-interventional magnetic resonance imaging (MRI). Analyses of DWI were evaluated and compared between pre-interventional MRI, 1.follow-up after 3 months and 2.follow-up at the time of the local tumor recurrence (in NR-HCC) or after 12 months (in R-HCC). Results: ADCmean of R-HCC increased significantly after HDR-BT on the first and second follow-up (ADCmean: 0.87 ± 0.18 × 10−3 mm2/s [pre-interventional]: 1.14 ± 0.23 × 10−3 mm2/s [1. post-interventional]; 1.42 ± 0.32 × 10−3 mm2/s [2. post-interventional]; P < 0.001). ADCmean of NR-HCC did not show a significant increase from pre-intervention to 1. post-interventional MRI (ADCmean: 0.85 ± 0.24 × 10−3 mm2/s and 1.00 ± 0.30 × 10−3 mm2/s, respectively; P = 0.131). ADCmean increase was significant between pre-intervention and 2. follow-up (ADCmean: 1.03 ± 0.19 × 10−3 mm2/s; P = 0.018). There was no significant increase of ADCmean between the first and second follow-up. There was, however, a significant increase of ADCmin after 12 months (ADCmin: 0.87 ± 0.29 × 10−3 mm2/s) compared to pre-interventional MRI and first follow-up (P < 0.005) only in R-HCC. Conclusion: The tumor response after CT-guided HDR-BT was associated with a significantly higher increase in ADCmean and ADCmin in short- and long-term follow-up. [ABSTRACT FROM AUTHOR]

Abstract Backround Hepatic radiation toxicity restricts irradiation of liver malignancies. Better knowledge of hepatic tolerance dose is favourable to gain higher safety and to optimize radiation regimes in radiotherapy of the liver. In this study we sought to determine the hepatic tolerance dose to small volume single fraction high dose rate irradiation. Materials and methods 23 liver metastases were treated by CT-guided interstitial brachytherapy. MRI was performed 3 days, 6, 12 and 24 weeks after therapy. MR-sequences were conducted with T1-w GRE enhanced by hepatocyte-targeted Gd-EOB-DTPA. All MRI data sets were merged with 3D-dosimetry data. The reviewer indicated the border of hypointensity on T1-w images (loss of hepatocyte function) or hyperintensity on T2-w images (edema). Based on the volume data, a dose-volume-histogram was calculated. We estimated the threshold dose for edema or function loss as the D90, i.e. the dose achieved in at least 90% of the pseudolesion volume. Results At six weeks post brachytherapy, the hepatocyte function loss reached its maximum extending to the former 9.4Gy isosurface in median (i.e., ≥9.4Gy dose exposure led to hepatocyte dysfunction). After 12 and 24 weeks, the dysfunctional volume had decreased significantly to a median of 11.4Gy and 14Gy isosurface, respectively, as a result of repair mechanisms. Development of edema was maximal at six weeks post brachytherapy (9.2Gy isosurface in median), and regeneration led to a decrease of the isosurface to a median of 11.3Gy between 6 and 12 weeks. The dose exposure leading to hepatocyte dysfunction was not significantly different from the dose provoking edema. Conclusion Hepatic injury peaked 6 weeks after small volume irradiation. Ongoing repair was observed up to 6 months. Individual dose sensitivity may differ as demonstrated by a relatively high standard deviation of threshold values in our own as well as all other published data.

Objective: Image-guided high-dose-rate interstitial brachytherapy (iBT) with iridium-192 is an effective treatment option for patients with liver malignancies. Little is known about long-term radiation effects on the bile duct system when central hepatic structures are exposed to iBT. This retrospective analysis investigates the occurrence of posthepatic cholestasis (PHC) and associated complications in patients undergoing iBT.Materials and Methods: We identified patients who underwent iBT of hepatic malignancies and had point doses of ≥1 Gy to central bile duct structures. Patients with known bile duct-related diseases or prior bile duct manipulation were excluded.Results: 102 patients were retrospectively included. Twenty-two patients (22%) developed morphologic PHC after a median of 17 (3-54) months; 18 of them were treated using percutaneous transhepatic cholangiopancreatography drainage or endoscopic retrograde cholangiopancreatography. The median point dose was 24.8 (4.4-80) Gy in patients with PHC versus 14.2 (1.8-61.7) Gy in those without PHC (p = 0.028). A dose of 20.8 Gy (biological effective dose, BED3/10 = 165/64.1 Gy) was identified to be the optimal cutoff dose (p = 0.028; 59% sensitivity, 24% specificity). Abscess/cholangitis was more common in patients with PHC compared to those without (4 of 22 vs. 2 of 80; p = 0.029). Median survival did not differ between patients with and without PHC (43 vs. 36 months; p = 0.571).Conclusion: iBT of liver malignancies located near the hilum can cause PHC when the central bile ducts are exposed to high point doses. Given the long latency and absence of impact of iBT-induced PHC on median survival, the rate of cholestasis and complications seen in our patients appears to be acceptable. [ABSTRACT FROM AUTHOR]