Prediction and monitoring of treatment effect using T1-weighted dynamic contrast-enhanced magnetic resonance imaging in colorectal liver metastases: Potential of whole tumour ROI and selective ROI analysis

Purpose

To evaluate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for prediction and early monitoring of treatment in colorectal liver metastases.

Materials and methods

Ten patients were included. Baseline and follow-up DCE-MRI examinations were evaluated by whole tumour and selected ROI placements calculating Kep-values. Selective ROIs, concentric-like and hot spot, were drawn on early arterial phase images. Monitoring of treatment was performed comparing RECIST1.1 criteria with whole tumour and selected ROI placement. To evaluate treatment effect between responders and non-responders, independent samples t-test was used on Kep-values.

Results

In each patient largest lesion was evaluated totalling 10 target lesions. At baseline, for whole tumour ROI placements mean Kep-values in responders were significantly higher than mean Kep-values in non-responders (t = 7.481, p < 0.001). Selective ROI placement comparison of mean Kep-values at baseline and after 6 weeks of treatment (first follow-up measurement) showed significant decrease in responding patients (t = 4.706, p = 0.003) whereas increase in Kep-values in non-responding patients was not statistically significant.

Conclusion

This preliminary study shows that baseline Kep for whole tumour ROI is a predictor for treatment outcome. Decrease of Kep using selective ROIs allows early identification of response after 6 weeks of treatment.     

Evaluation of true diffusion, perfusion factor, and apparent diffusion coefficient in non-necrotic liver metastases and uncomplicated liver hemangiomas using black-blood echo planar imaging

Purpose

To assess the added value of true diffusion (D), perfusion factor (f) and apparent diffusion coefficient at low b-values (ADC_low) for differentiation between liver metastases and hemangiomas based on respiratory-triggered high-resolution Black-Blood Single-Shot SpinEcho Echo Planar Imaging (BB SS SE-EPI).

Materials and methods

Twenty-five patients suspected for malignant colorectal liver lesions were included in this study. A total of 106 lesions were examined. Different b-value images were compared for lesion conspicuity, image quality and artifacts using rank order statistic (RIDIT) and Student's t-test. D, f, and ADC_low values were calculated. Pearson correlation coefficient is used for comparison of interobserver variability.

Results

Best lesion conspicuity (p < 0.05) was achieved with BB SS SE-EPI (b = 0 and 10 s/mm²); best image quality (p < 0.05) with b = 10 s/mm². Image artifacts were lowest (p < 0.05) with b = 0 s/mm². Over the whole sample, D in metastases (D_met) was significantly (p < 0.05) lower than D in hemangiomas (D_hem); f and ADC_low of metastases (f_met, respectively, ADC_low met) were significantly (p < 0.05) higher than f and ADC_low of hemangiomas (f_hem, respectively, ADC_low hem). All Pearson correlations were statistically significant at a 0.01 level.

Conclusions

This preliminary study shows the potential of BB SS SE-EPI as a useful technique to aid in differentiating between liver metastasis and hemangioma. The calculation of D, f and ADC_low provides useful additional information for differentiating metastases from hemangiomas.     

Comparison of MRI (including SS SE-EPI and SPIO-enhanced MRI) and FDG-PET/CT for the detection of colorectal liver metastases

Fluoro-18-deoxyglucose positron emission tomography computed tomography (FDG-PET/CT) and magnetic resonance imaging (MRI), including unenhanced single-shot spin-echo echo planar imaging (SS SE-EPI) and small paramagnetic iron oxide (SPIO) enhancement, were compared prospectively for detecting colorectal liver metastases. Twenty-four consecutive patients suspected for metastases underwent MRI and FDG-PET/CT. Fourteen patients (58%) had previously received chemotherapy, including seven patients whose chemotherapy was still continuing to within 1 month of the PET/CT study. The mean interval between PET/CT and MRI was 10.2 ± 5.2 days. Histopathology (n = 18) or follow-up imaging (n = 6) were used as reference. Seventy-seven metastases were detected. In nine patients, MRI and PET/CT gave concordant results. Sensitivities for unenhanced SS SE-EPI, MRI without SS SE-EPI and FDG-PET/CT were, respectively, 100% (p = 9 × 10⁻¹⁰ vs PET, p = 8 × 10⁻³ vs MRI without SS SE-EPI), 90% (p = 2 × 10⁻⁷ vs PET) and 60%. PET/CT sensitivity dropped significantly with decreasing size, from 100% in lesions larger than 20 mm (identical to MRI), over 54% in lesions between 10 and 20 mm (p = 3 × 10⁵ versus unenhanced SS SE-EPI), to 32% in lesions under 10 mm (p = 6 × 10⁻⁵ versus unenhanced SS SE-EPI). Positive predictive value of PET was 100% (identical to MRI). MRI, particularly unenhanced SS SE-EPI, has good sensitivity and positive predictive value for detecting liver metastases from colorectal carcinoma. Its sensitivity is better than that of FDG-PET/CT, especially for small lesions.     

Congenital intrahepatic porto-systemic shunt.

An asymptomatic case of intrahepatic shunt between a portal and hepatic vein is presented. Ultrasound examination combined with Doppler sonography showed a communication between a dilated portal vein and a hepatic vein. Computed tomography and angiography confirmed the findings. Porto-hepatic venous shunting is very rare and has previously been reported in association with cirrhosis. The vascular malformation we present is believed to be a congenital anomaly, as no signs of cirrhosis or trauma were found.     

Improved focal liver lesion detection: comparison of single-shot spin-echo echo-planar and superparamagnetic iron oxide (SPIO)-enhanced MRI

PURPOSE: To prospectively compare single-shot spin-echo echo-planar imaging (SSSE-EPI) using b = 0, 10, 150, and 400 seconds/mm(2) with standard MRI techniques after intravenous super paramagnetic iron oxide (SPIO) in the detection and characterization of focal liver lesions with focus on small (<10 mm) focal liver lesions. MATERIALS AND METHODS: A total of 25 patients suspected for colorectal liver metastases were included. Number of detected lesions was evaluated. Image quality was compared between SSSE-EPI sequence and post-SPIO (fat-suppressed T1-weighted [T1w] gradient echo [GE], T2-weighted [T2w] turbo spin echo [TSE] and T2* GE) sequences using rank order statistic (RIDIT). Lesion characterization was performed for SSSE-EPI and for all remaining sequences pre- and post-SPIO. Reference standard comprised surgery, biopsy, and/or follow-up. RESULTS: Reference standard demonstrated 25 hemangiomas and 70 metastases. Best lesion detection respectively best image quality (P < 0.05) was achieved with SSSE-EPI (b = 10 seconds/mm(2)) post-SPIO T1w GE and T2w turbo spin echo. Lesion characterization using all sequences pre- and post-SPIO performed best for lesion characterization compared with SSSE-EPI. CONCLUSION: This preliminary study shows the potential of SSSE-EPI as a stand-alone sequence for the detection of liver hemangiomas and metastases when compared with SPIO-enhanced imaging. Sequences pre- and post-SPIO are needed for qualitative lesion characterization.     

Erythromycin-induced hepatitis: simulator of malignancy

A 67-year-old patient was admitted with a 2-week history of epigastric discomfort that began after an episode of upper respiratory tract infection treated with erythromycin. Results of liver function tests were abnormal. Abdominal ultrasound (US) and computed tomography showed multiple, poorly demarcated irregular lesions in both hepatic lobes, suggestive of diffuse metastatic invasion. Histologic examination of the biopsy specimen revealed drug-induced hepatitis. Ten weeks after withdrawal of the erythromycin, US showed complete resolution of the hyperechogenic liver lesions.     

Perfusion maps of the whole liver based on high temporal and spatial resolution contrast-enhanced MRI (4D THRIVE): Feasibility and initial results in focal liver lesions

Purpose

To prospectively evaluate a new imaging sequence (4D THRIVE) for whole liver perfusion in high temporal and spatial resolution. Feasibility of parametric mapping and its potential for characterizing focal liver lesions (FLLs) are investigated.

Materials and methods

Fifteen patients suspected for colorectal liver metastases (LMs) were included. Parametric maps were evaluated qualitatively (ring-enhancement and lesion heterogeneity) and compared to three-phased contrast-enhanced MRI. Quantitative analysis was based on average perfusion values of entire FLLs. Reference standard comprised surgery with histopathology or follow-up imaging. Fisher's exact test was used for qualitative and Kruskal-Wallis test for quantitative analysis.

Results

In total 29 LMs, 17 hemangiomas and 4 focal nodular hyperplasias were evaluated. FLLs could be differentiated by qualitative assessment of parametric maps respectively three-phased contrast-enhanced MRI (Fisher's p < 0.001 for comparisons between LMs and hemangiomas and LMs and FNHs for both ring-enhancement and lesion heterogeneity) rather than by quantitative analysis of parametric maps (Chi-square for Kep = 0.33 (p = 0.847) and Chi-square for Kel = 1.35 (p = 0.509)).

Conclusion

This preliminary study shows potential of 4D THRIVE for whole liver imaging enabling calculation of parametric maps. Qualitative rather than quantitative analysis was accurate for differentiating malignant and benign FLLs.     

Focal liver lesion detection and characterization: comparison of non-contrast enhanced and SPIO-enhanced diffusion-weighted single-shot spin echo echo planar and turbo spin echo T2-weighted imaging

Purpose

To compare lesion conspicuity and image quality between single-shot spin echo echo planar imaging (SS SE-EPI) before, immediately and 5 min after intravenous (IV) injection of superparamagnetic iron oxide (SPIO) for detecting and characterizing focal liver lesions (FLLs).

Materials and methods

Twenty-five patients suspected for colorectal liver metastases were prospectively included. Lesion detection and characterization were compared between all SS SE-EPI and T2-weighted turbo spin echo (T2w TSE) sets (two-sided Fisher’s exact test). Image quality and lesion conspicuity were compared for SS SE-EPI sets using rank order statistic (RIDIT). Reference standard comprised of surgery, biopsy and/or follow-up.

Results

Reference standard demonstrated 18 benign and 43 malignant FLLs. Best lesion detection (p < 0.05) was achieved with non-contrast-enhanced SS SE-EPI. Lesion characterization was best using all T2w TSE sequences. Best image quality and lesion conspicuity (p < 0.05) was achieved with non-contrast-enhanced SS SE-EPI.

Conclusion

Non-contrast-enhanced SS SE-EPI was best for lesion detection. SS SE-EPI sequences were not useful for lesion characterization (differentiation between benign and malignant lesions). Unenhanced SS SE-EPI did not allow differentiation especially as many benign FLLs were hyperintense on the highest b-value images. Combining unenhanced and SPIO-enhanced SS SE-EPI performed better but still was not clinically useful due to variable degree of uptake and vascular pooling of SPIO for (especially) benign FLLs. T2w TSE with SPIO-enhancement was needed for characterization.     

Chronic focal fibrosing pancreatitis: detection by MRI.

The study of a 70-year-old woman with fibrosing pancreatitis, an uncommon variety of chronic pancreatitis, presenting as a discrete solid mass in the head of the pancreas, is reported. CT and US were non-diagnostic while ERCP and MR detected a focal anomaly. This case report stresses the sensitivity of MR in some pancreatic pathologies.