Diffusion-weighted MRI (DWI) for assessment of response to high-dose-rate CT-guided brachytherapy (HDR-BT) of hepatocellular carcinoma.

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.

Economic evaluation of 18F-FDG PET/CT, MRI and CE-CT in selection of colorectal liver metastases eligible for ablation - A cost-effectiveness analysis.

OBJECTIVES: Colorectal cancers (CRC) are among the world's most prevailing cancer entities. In a third of all cases, the patients have already developed distant metastases - mainly in the liver - at the time of detection. Colorectal liver metastases (CRLM) can be treated by surgical resection or, as is possible in most cases, by percutaneous ablation. For selecting the liver metastases eligible for radiofrequency ablation (RFA) or microwave ablation (MWA), the common imaging modalities are magnetic resonance imaging (MRI), positron emission tomography/computed tomography (PET/CT), and contrast-enhanced computed tomography (CE-CT). This study aims to evaluate those imaging modalities for selecting liver lesions eligible for ablation according to their long-term cost-effectiveness. MATERIALS AND METHODS: A Markov model was applied, calculating quality-adjusted life years (QALYs) and accumulative costs for every diagnostic strategy, according to predefined input parameters obtained from published research. Further, sensitivity analyses were executed to prove the certainty of the calculations by running Monte-Carlo simulations with 30,000 reiterations. The Willingness-to-pay (WTP) is at $ 100,000. All calculations are based on the U.S. healthcare system. RESULTS: CE-CT caused cumulative costs of $ 31,940.98 and 8,99 QALYs, whereas MRI caused $ 32,070.83 and 9,01 QALYs. PET/CT caused cumulative costs of $ 33,013.21 and 8,99 QALYs. CONCLUSION: In conclusion, according to our analysis, MRI is the most cost-effective strategy for detecting liver metastases eligible for ablation and therefore should be seen as the gold standard.

Treatment Assessment of pNET and NELM after Everolimus by Quantitative MRI Parameters.

Assessment of treatment response to targeted therapies such as everolimus is difficult, especially in slow-growing tumors such as NETs. In this retrospective study, 17 patients with pancreatic neuroendocrine tumors (pNETs) and hepatic metastases (NELMs) (42 target lesions) who received everolimus were analyzed. Intralesional signal intensities (SI) of non-contrast T1w, T2w and DCE imaging, and apparent diffusion coefficients (ADCmean and ADCmin) of DWI, were measured on baseline and first follow-up MRI after everolimus initiation. Response assessment was categorized according to progression-free survival (PFS), with responders (R) showing a PFS of ≥11 months. ADCmin of NELMs decreased in Rs whereas it increased in non-responders (NR). Percentual changes of ADCmin and ADCmean differed significantly between response groups (p < 0.03). By contrast, ADC of the pNETs tended to increase in Rs, while there was no change in NRs. Tumor-to-liver (T/L) ratio of T1 SI of NELMs increased in Rs and decreased in NRs, and percentual changes differed significantly between response groups (p < 0.02). T1 SI of the pNETs tended to decrease in Rs and increase in Ns. The quotient of pretherapeutic and posttherapeutic ADCmin values (DADCmin) and length of everolimus treatment showed significant association with PFS in univariable Cox analysis. In conclusion, quantitative MRI, especially DWI, seems to allow treatment assessment of pNETs with NELMs under everolimus. Interestingly, the responding NELMs showed decreasing ADC values, and there might be an opposite effect on ADC and T1 SI between NELMs and pNETs.

Diagnostic Workup for Patients with Solid Renal Masses: A Cost-Effectiveness Analysis.

BACKGROUND: For patients with solid renal masses, a precise differentiation between malignant and benign tumors is crucial for forward treatment management. Even though MRI and CT are often deemed as the gold standard in the diagnosis of solid renal masses, CEUS may also offer very high sensitivity in detection. The aim of this study therefore was to evaluate the effectiveness of CEUS from an economical point of view. METHODS: A decision-making model based on a Markov model assessed expenses and utilities (in QALYs) associated with CEUS, MRI and CT. The utilized parameters were acquired from published research. Further, a Monte Carlo simulation-based deterministic sensitivity analysis of utilized variables with 30,000 repetitions was executed. The willingness-to-pay (WTP) is at USD 100,000/QALY. RESULTS: In the baseline, CT caused overall expenses of USD 10,285.58 and an efficacy of 11.95 QALYs, whereas MRI caused overall expenses of USD 7407.70 and an efficacy of 12.25. Further, CEUS caused overall expenses of USD 5539.78, with an efficacy of 12.44. Consequently, CT and MRI were dominated by CEUS, and CEUS remained cost-effective in the sensitivity analyses. CONCLUSIONS: CEUS should be considered as a cost-effective imaging strategy for the initial diagnostic workup and assessment of solid renal masses compared to CT and MRI.

Apparent diffusion coefficients (ADC) in response assessment of transarterial radioembolization (TARE) for liver metastases of neuroendocrine tumors (NET): a feasibility study.

BACKGROUND: In patients with hepatic neuroendocrine tumors (NETs) locoregional therapies such as transarterial radioembolization (TARE) are increasingly applied. Response evaluation remains challenging and previous studies assessing response with diffusion-weighted imaging (DWI) have been inconclusive. PURPOSE: To perform a feasibility study to evaluate if response assessment with quantitative apparent diffusion coefficient (ADC) in patients with liver metastases of NETs after TARE will be possible. MATERIAL AND METHODS: Retrospectively, 43 patients with 120 target lesions who obtained abdominal magnetic resonance imaging (MRI) with DWI 39±28 days before and 74±46 days after TARE were included. Intralesional ADC (ADCmin, ADCmax, and ADCmean) were measured for a maximum number of three lesions per patient on baseline and post-interventional DWI. Tumor response was categorized according to RECIST 1.1 and mRECIST. RESULTS: TARE resulted in partial remission (PR) in 23% (63%), in stable disease (SD) in 73% (23%), in progressive disease (PD) in 5% (7%) and in complete response (CR) in 0% (1%) according to RECIST 1.1 (mRECIST, respectively). ADC values increased significantly (P<0.005) after TARE in the PR group whereas there was no significant change in the PD group. Post-therapeutic ADC values of SD lesions increased significantly when evaluated by RECIST 1.1 but not if evaluated by mRECIST. Percentual changes of ADCmean values were slightly higher for responders compared to non-responders (P<0.05). CONCLUSION: ADC values seem to represent an additional marker for treatment response evaluation after TARE in patients with secondary hepatic NET. A conclusive study seems feasible though patient-based evaluation and overall survival and progression free survival as alternate primary endpoints should be considered.

68Ga-DOTATATE PET/CT and MRI with Diffusion-Weighted Imaging (DWI) in Short- and Long-Term Assessment of Tumor Response of Neuroendocrine Liver Metastases (NELM) Following Transarterial Radioembolization (TARE).

The aim of this study was to evaluate the role of SUV and ADC in assessing early response in patients with NELM following TARE. Thirty-two patients with pre- and postinterventional MRI with DWI and 68Ga-DOTATATE PET/CT were included. ADC and SUV of three target lesions and of tumor-free spleen and liver tissue were determined on baseline and first follow-up imaging, and tumor to spleen (T/S) and tumor to liver (T/L) ratios were calculated. Response was assessed by RECIST 1.1 and mRECIST on first follow-up, and long-term response was defined as hepatic progression-free survival (HPFS) over 6, 12, and <24 months. In responders, intralesional ADC values increased and SUV decreased significantly regardless of standard of reference for response assessment (mRECIST/RECIST/HPFS > 6/12/24 m). Using ROC analysis, ΔSUV T/S ratio (max/max) and ΔSUV T/L ratio (max/mean) were found to be the best and most robust metrics to correlate with longer HPFS and were superior to ΔADC. ΔT/S ratio (max/max) < 23% was identified as an optimal cut-off to discriminate patients with longer HPFS (30.2 m vs. 13.4 m; p = 0.0002). In conclusion, early percentage changes in SUV tumor-to-organ ratios on first follow-up seem to represent a prognostic marker for longer HPFS and may help in assessing therapeutic strategies.

The role of diffusion-weighted MRI in assessment of inflammatory bowel disease.

AIM: To evaluate the role of diffusion-weighted MRI (DW-MRI) in detecting and differentiating acute from chronic bowel inflammation in patients with Crohn's disease (CD). MATERIALS AND METHODS: MR-enteroclysis examinations with DW-MRI were reviewed from 24 patients with histologically proven CD. Segments of bowel were evaluated for acute and chronic inflammation in three different reviews of the MRI images: T2w alone, T2w + DWI, and T2w + CET1w. Mean ADC values of normal bowel segments, as well as bowel segments with acute and chronic inflammation were calculated and compared. Analyses of receiver-operating characteristic (ROC) curve were performed. RESULTS: Hundred and forty four bowel segments in total were reviewed. Inflammation was present in 45 segments. Acute inflammation was present in 31 segments, chronic inflammation in 14. 98 bowel segments showed no inflammatory activity. Sensitivity and specificity for differentiation between normal and inflamed bowel segments was 0.6, 0.67, and 0.80 on T2w, T2w + DWI, and T2w + CET1w datasets, respectively. Specificities for differentiation between normal and inflamed bowel segments were 0.96, 0.96, and 0.98. Sensitivities for differentiation between acute and chronically inflamed bowel segments were 0.85, 0.91, and 0.96, and specificities were 0.88, 0.89, and 1.0, respectively. The mean ADC value of normal bowel (2.18 ± 0.37 × 10(-3) mm(2)/s) was statistically significantly greater than the mean value of inflamed bowel segments (p < 0.001). The mean ADC value of acutely inflamed bowel segments was statistically significantly lower than that of chronically inflamed bowel segments (1.09 ± 0.18 × 10(-3) vs. 1.55 ± 0.21 × 10(-3) mm(2)/s) (p < 0.001). Estimated area under the ROC curve for the diagnosis of acute vs. chronic inflammation was 0.950. A threshold of ADC value of 1.41 × 10(-3) mm(2)/s was optimal for calculation of sensitivity and specificity. CONCLUSION: DW-MRI improves detection and differentiation of acute vs. chronic inflammatory changes of the bowel in patients with CD compared to T2w-images alone.