Role of diffusion-weighted imaging in response prediction and evaluation after high dose rate brachytherapy in patients with colorectal liver metastases

BACKGROUND

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.

PATIENTS AND METHODS

In this retrospective, observational cohort study, we included 19 patients with 18 responding metastases (R-Mets; follow-up at least one year) and 11 non-responding metastases (NR-Mets; local tumor recurrence within one year) who were treated with high-dose-rate brachytherapy (HDR-BT) and underwent pre- and post-interventional MRI. DWI (qualitatively, mean apparent diffusion coefficient [ADCmean], ADCmin, intraindividual change of ADCmean and ADCmin) were evaluated and compared between pre-interventional MRI, first follow-up after 3 months and second follow-up at the time of the local tumor recurrence (in NR-Mets, mean: 284 ± 122 d) or after 12 months (in R-Mets, mean: 387+/-64 d). Sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) for detection of local tumor recurrence were calculated on second follow up, evaluating (1) DWI images only, and (2) DWI with Gd-enhanced T1-weighted images on hepatobiliary phase (contrast-enhanced [CE] T1-weight [T1w] hepatobiliary phase [hb]).

RESULTS

ADCmean significantly increased 3 months after HDR-BT in both groups (R-Mets: 1.48 ± 0.44 and NR-Mets: 1.49 ± 0.19 x 10-3 mm2;/s, p < 0.0001 and p = 0.01), however, intraindividual change of ADCmean (175% vs.127%, p = 0.03) and ADCmin values (0.44 ± 0.24 to 0.82 ± 0.58 x 10-3 mm2/s) significantly increased only in R-Mets (p < 0.0001 and p < 0.001). ADCmin was significant higher in R-Mets compared to NR-Mets on first follow-up (p = 0.04). Sensitivity (1 vs. 0.72), specificity (0.94 vs. 0.72), PPV (0.91 vs. 0.61) and NPV (1 vs. 0.81) could be improved by combining DWI with CE T1w hb compared to DWI only.

CONCLUSIONS

DW-MRI seems to be helpful in the qualitative and quantitative evaluation of treatment response after HDR-BT of colorectal metastases in the liver.

Clinical Significance of Intraluminal Contrast Enhancement in Patients with Spontaneous Cervical Artery Dissection: A Black-Blood MRI Study

Purpose Recent studies have suggested that intraluminal thrombi show contrast enhancement on carotid black-blood T1w MRI. The aim of this study was to evaluate the significance of intraluminal contrast enhancement (iCE) regarding symptom status in patients with spontaneous cervical artery dissection (sCAD). Methods 33 consecutive patients (19 men) with sCAD received a brain MRI (DIFF, T2w, T2*w, FLAIR) and a multi-sequence 3T-MRI with fat-saturated high-resolution black-blood T1w-sequences pre- and post-contrast, contrast-enhanced MR angiography and TOF images of carotid and vertebral arteries. Presence/absence of iCE, vessel occlusion and vessel wall hematoma (hyperintense in T1w pre-contrast) were analysed by two radiologists in consensus decision. Results 44 of 132 analysed vessels had a vessel wall hematoma, consistent with sCAD. In 17 of 44 dissected vessels an acute ischemic stroke was found. 16 of 17 (94.1 %) vessels ipsilateral to ischemic stroke demonstrated iCE, compared to 9 of 44 (20.4 %) dissected vessels without stroke (P< 0.001). The presence/absence of iCE resulted in a sensitivity, specificity, positive and negative predictive value and accuracy for ischemic stroke of 0.94, 0.67, 0.64, 0.95, and 0.77, respectively, and an odds ratio of 32.0. Conclusion iCE, which is suggestive of intraluminal thrombus formation, is strongly correlated with ischemic symptoms in patients with sCAD. Key points  · Intraluminal contrast enhancement is associated with cerebral ischemia in corresponding vessel territories in patients with cervical artery dissection.. · Our results suggest that intraluminal contrast enhancement represents intraluminal thrombus formation.. · Black-blood imaging might be useful to identify those patients with cervical artery dissection at higher risk for initial or recurrent stroke.. Citation Format · Coppenrath E, Lenz O, Sommer N et al. Clinical Significance of Intraluminal Contrast Enhancement in Patients with Spontaneous Cervical Artery Dissection: A Black-Blood MRI Study. Fortschr Röntgenstr 2017; 189: 624 - 631.