Blood oxygen level–dependent functional magnetic resonance imaging can evaluate the efficiency of transcatheter arterial chemoembolization in hepatocellular carcinoma

Evaluating the diagnostic significance of the R2* value on 3.0T MRI for assessing the severity of warm hepatic ischemia-reperfusion injury

BACKGROUND

Magnetic resonance imaging (MRI) may be a non-invasive tool for managing warm hepatic ischemia-reperfusion injury (WHIRI).

PURPOSE

We aimed to evaluate the diagnostic utility of the R2* values derived from 3.0T blood oxygen level-dependent (BOLD) MRI in assessing the severity of WHIRI.

METHODS

Fifty healthy adult New Zealand white rabbits were randomly divided into 5 groups with 10 rabbits in each. The experimental groups (40 rabbits) underwent clamping of the hepatic artery and the portal vein for 10, 20, 30, or 40 min, followed by 6 h of reperfusion to induce WHIRI. The other 10 rabbits comprised the normal control group. All animals were underwent conventional 3.0 T and BOLD MRI. Animals were euthanized and the serum levels of biochemical indicators were determined. Correlations between R2* values, biochemical indicators, and WHIRI staging were assessed using Spearman's rank correlation coefficient. The diagnostic efficacy of R2* values was evaluated using ROC curves.

RESULTS

R2* values increased gradually with prolonged warm ischemia with significant differences across groups (F = 133.25, P < 0.05). A strong positive correlation was detected between R2* values and WHIRI staging (r = 0.878, P = 0.000). Biochemical indicators (ALT, AST, LDH, MDA, and MPO) increased significantly, while SOD levels decreased with prolonged warm ischemia (P < 0.05). R2* values exhibited a strong positive correlation with biochemical indicators (r > 0.495) and a negative correlation with SOD levels (r=-0.658). The diagnostic efficacy of the R2* values was highest for predicting WHIRI above stage S4 (AUC = 1.000).

CONCLUSION

R2* values on BOLD MRI provide a sensitive and accurate method for assessing WHIRI. The diagnostic efficacy of the R2* values was the best for predicting WHIRI above stage S4.

Photoacoustic monitoring of oxygenation changes induced by therapeutic ultrasound in murine hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is a highly vascular solid tumor. We have previously shown that ultrasound (US) therapy significantly reduces tumor vascularity. This study monitors US-induced changes in tumor oxygenation on murine HCC by photoacoustic imaging (PAI). Oxygen saturation and total hemoglobin were assessed by PAI before and after US treatments performed at different intensities of continuous wave (CW) bursts and pulsed wave (PW) bursts US. PAI revealed significant reduction both in HCC oxygen saturation and in total hemoglobin, proportional to the US intensity. Both CW bursts US (1.6 W/cm2) and the PW bursts US (0.8 W/cm2) significantly reduced HCC oxygen saturation and total hemoglobin which continued to diminish with time following the US treatment. The effects of US therapy were confirmed by power Doppler and histological examination of the hemorrhage in tumors. By each measure, the changes observed in US-treated HCC were more prevalent than those in sham-treated tumors and were statistically significant. In conclusion, the results show that US is an effective vascular-targeting therapy for HCC. The changes in oxygenation induced by the US treatment can be noninvasively monitored longitudinally by PAI without the use of exogenous image-enhancing agents. The combined use of PAI and the therapeutic US has potential for image-guided vascular therapy for HCC.