Assessment of hepatic sinusoidal obstruction syndrome with intravoxel incoherent motion diffusion-weighted imaging: An experimental study in a rat model

Gadoxetic acid-enhanced magnetic resonance imaging in the assessment of hepatic sinusoidal obstruction syndrome in a mouse model

BACKGROUND

Neoadjuvant chemotherapy can cause hepatic sinusoidal obstruction syndrome (SOS) in patients with colorectal cancer liver metastases and increases postoperative morbidity and mortality.

AIM

To evaluate T1 mapping based on gadoxetic acid-enhanced magnetic resonance imaging (MRI) for diagnosis of hepatic SOS induced by monocrotaline.

METHODS

Twenty-four mice were divided into control (n = 10) and experimental (n = 14) groups. The experimental groups were injected with monocrotaline 2 or 6 days before MRI. MRI parameters were: T1 relaxation time before enhancement; T1 relaxation time 20 minutes after enhancement (T1post); a reduction in T1 relaxation time (△T1%); and first enhancement slope percentage of the liver parenchyma (ESP). Albumin and bilirubin score was determined. Histological results served as a reference. Liver parenchyma samples from the control and experimental groups were analyzed by western blotting, and organic anion transporter polypeptide 1 (OATP1) was measured.

RESULTS

T1post, △T1%, and ESP of the liver parenchyma were significantly different between two groups (all P < 0.001) and significantly correlated with the total histological score of hepatic SOS (r = -0.70, 0.68 and 0.79; P < 0.001). △T1% and ESP were positively correlated with OATP1 levels (r = 0.82, 0.85; P < 0.001), whereas T1post had a negative correlation with OATP1 levels (r = -0.83; P < 0.001).

CONCLUSION

T1 mapping based on gadoxetic acid-enhanced MRI may be useful for diagnosis of hepatic SOS, and MRI parameters were associated with OATP1 levels.

Application of Intravoxel Incoherent Motion in Clinical Liver Imaging: A Literature Review

Intravoxel incoherent motion (IVIM) modeling is a widely used double-exponential model for describing diffusion-weighted imaging (DWI) signal, with a slow component related to pure molecular diffusion and a fast component associated with microcirculatory perfusion, which compensates for the limitations of traditional DWI. IVIM is a noninvasive technique for obtaining liver pathological information and characterizing liver lesions, and has potential applications in the initial diagnosis and treatment monitoring of liver diseases. Recent studies have demonstrated that IVIM-derived parameters are useful for evaluating liver lesions, including nonalcoholic fatty liver disease (NAFLD), liver fibrosis and liver tumors. However, the results are not stable. Therefore, it is necessary to summarize the current applications of IVIM in liver disease research, identify existing shortcomings, and point out the future development direction. In this review, we searched for studies related to hepatic IVIM-DWI applications over the past two decades in the PubMed database. We first introduce the fundamental principles and influential factors of IVIM, and then discuss its application in NAFLD, liver fibrosis, and focal hepatic lesions. It has been found that IVIM is still unstable in ensuring the robustness and reproducibility of measurements in the assessment of liver fibrosis grade and liver tumors differentiation, due to inconsistent and substantial overlap in the range of IVIM-derived parameters for different fibrotic stages. In the end, the future direction of IVIM-DWI in the assessment of liver diseases is discussed, emphasizing the need for further research on the stability of IVIM-derived parameters, particularly perfusion-related parameters, in order to promote the clinical practice of IVIM-DWI. LEVEL OF EVIDENCE: 5 TECHNICAL EFFICACY: Stage 3.

Repeatability and reproducibility comparisons of liver IVIM imaging with free-breathing or respiratory-triggered sequences

For liver intravoxel incoherent motion (IVIM) data acquisition, respiratory-triggering (RT) MRI is commonly used, and there are strong motivations to shorten the scan duration. For the same scan duration, more b values or higher numbers of excitations can be allowed for free-breathing (FB) imaging than for RT. We studied whether FB can be used to replace RT when careful IVIM image acquisition and image processing are conducted. MRI data of 22 healthy participants were acquired using a 3.0 T scanner. Diffusion imaging was based on a single-shot spin-echo-type echo-planar sequence and 16 b values of 0, 2, 4, 7, 10, 15, 20, 30, 46, 60, 72, 100, 150, 200, 400, and 600 s/mm2 . Each subject attended two scan sessions with an interval of 10-20 days. For each scan session, a subject was scanned twice, first with RT and then with FB. The mean image acquisition time was 5.4 min for FB and 10.8 min for RT. IVIM parameters were calculated with bi-exponential model segmented fitting with a threshold b value of 60 s/mm2 , and fitting started from b = 2 s/mm2 . There was no statistically significant difference between IVIM parameters measured with FB imaging or RT imaging. Perfusion fraction ICC (intraclass correlation coefficient) for FB imaging and RT imaging in the same scan session was 0.824. For perfusion fraction, wSD (within-subject standard deviation), BA (Bland-Altman) difference, BA 95% limit, and ICC were 0.022, 0.0001, -0.0635~0.0637, and 0.687 for FB and 0.031, 0.0122, -0.0723~0.0967, and 0.611 for RT. For Dslow (×10-3  s/mm2 ), wSD, BA difference, BA 95% limit, and ICC were 0.057, 0.0268, -0.1258~0.1793, and 0.471 for FB and 0.073, -0.0078, -0.2170-0.2014, and <0.4 for RT. The Dfast coefficient of variation was 0.20 for FB imaging and 0.28 for RT imaging. All reproducibility indicators slightly favored FB imaging.

Hepatic sinusoidal obstruction syndrome/veno-occlusive disease after hematopoietic cell transplantation: historical and current considerations in Korea

Hepatic sinusoidal obstruction syndrome/veno-occlusive disease (SOS/VOD) is a rare but severe complication of hematopoietic cell transplantation (HCT) showing high mortality. Multiple risk factors for SOS/VOD were identified, but it is often confused with other hepatic complications due to nonspecific clinical features. Therefore, diagnostic and severity criteria have been revised several times. The European Society of Blood and Marrow Transplantation suggested a new guideline that excludes the standard duration of development within 21 days, emphasizes late-onset SOS/VOD, and suggests the importance of Doppler ultrasonography. The severity criteria were further subdivided for guidance to begin active treatment using defibrotide which was approved in Korea since 2016. In a phase 3 trial, defibrotide had superior 100-day survival, compared to best available treatments (38.2% vs. 25.0%). Although several studies of SOS/VOD in Korean patients have been performed after the implementation of HCT, most involved small number of pediatric patients. Recently, the Korean Society of Blood and Marrow Transplantation investigated the incidence of SOS/VOD in the Korean population, and several influential studies of adult patients were published. Here, we summarize recent issues regarding the mechanism, diagnosis, severity criteria, prevention, and treatments of SOS/VOD in Korean patients, as well as recent analyses of nationwide incidence.

T1 Mapping on Gd-EOB-DTPA-Enhanced MRI for the Prediction of Oxaliplatin-Induced Liver Injury in a Mouse Model

BACKGROUND

Oxaliplatin-induced liver injury (OILI) not only impairs hepatic regeneration but also increases postoperative morbidity and mortality. Therefore, noninvasive, accurate, and early diagnosis of OILI is mandatory.

PURPOSE

To evaluate the potential of T₁ mapping on gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI for assessing OILI in a mouse model.

STUDY TYPE

Case control, animal model.

ANIMAL MODEL

Thirty oxaliplatin-treated mice and 10 control mice were included.

FIELD STRENGTH

Volumetric interpolated breath-hold examination sequence: 3T scanner with a phased-array animal 8-channel coil. T₁ mapping before and at hepatobiliary phase (HBP) after injection of Gd-EOB-DTPA were undertaken.

ASSESSMENT

T₁ relaxation times of the liver parenchyma were measured and the reduction rate (ΔT₁ %) was calculated. Histological findings were used as a standard reference.

STATISTICAL TESTS

The Kruskal-Wallis test with pairwise comparisons using the Mann-Whitney U-test were applied to compare the parameters across groups. Spearman's rank correlation test and receiver operating characteristics (ROC) analyses were performed. Areas under the curves (AUCs) were compared using the DeLong method.

RESULTS

Histologically, mice were classified as normal (n = 10), hepatocellular degeneration without fibrosis (n = 16), and hepatocellular degeneration with fibrosis (n = 14). HBP T₁ relaxation time increased with the severity of OILI (rho = 0.60, P < 0.05), and ΔT₁ % decreased with the severity of OILI (rho = -0.78, P < 0.05). AUC was 0.92 for ΔT₁ % in differentiating hepatocellular degeneration without fibrosis from normal liver, but HBP T₁ relaxation time could not distinguish them (P = 0.09). AUCs were 0.96 and 0.95 for HBP T₁ relaxation time, and 0.90 and 0.84 for ΔT₁ % in discriminating OILI with fibrosis from normal liver and OILI without fibrosis.

DATA CONCLUSION

HBP T₁ relaxation time and ΔT₁ % of Gd-EOB-DTPA enhanced MRI was useful for assessing OILI. ΔT₁ % may be more sensitive than HBP T₁ relaxation time in detecting early stage of liver injury.

LEVEL OF EVIDENCE

2.

TECHNICAL EFFICACY STAGE

5.

Progress of intravoxel incoherent motion diffusion-weighted imaging in liver diseases

Traditional magnetic resonance (MR) diffusion-weighted imaging (DWI) uses a single exponential model to obtain the apparent diffusion coefficient to quantitatively reflect the diffusion motion of water molecules in living tissues, but it is affected by blood perfusion. Intravoxel incoherent motion (IVIM)-DWI utilizes a double-exponential model to obtain information on pure water molecule diffusion and microcirculatory perfusion-related diffusion, which compensates for the insufficiency of traditional DWI. In recent years, research on the application of IVIM-DWI in the diagnosis and treatment of hepatic diseases has gradually increased and has achieved considerable progress. This study mainly reviews the basic principles of IVIM-DWI and related research progress in the diagnosis and treatment of hepatic diseases.

Editorial for "Non-Gaussian Diffusion Models and T1rho Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in Rats"

LEVEL OF EVIDENCE

5 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:1122-1123.

Non-Gaussian Diffusion Models and T1 rho Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in Rats

BACKGROUND

Non-Gaussian diffusion models and T₁ rho quantification may reflect the changes in tissue heterogeneity in hepatic sinusoidal obstruction syndrome (SOS).

PURPOSE

To investigate the feasibility of diffusion kurtosis imaging (DKI), stretched exponential model (SEM), and T₁ rho quantification in detecting and staging SOS in a monocrotaline (MCT)-induced rat model.

STUDY TYPE

Animal study.

POPULATION

Thirty male Sprague-Dawley rats gavaged with MCT to induce hepatic SOS and six male rats without any intervention.

FIELD STRENGTH/SEQUENCE

3.0T, DWI with five b-values (0-2000 s/mm² ) and T₁ rho with five spin lock times (1-60 msec).

ASSESSMENT

MRI was performed 1 day before and 1, 3, 5, 7, and 10 days after MCT administration. The corrected apparent diffusion coefficient (D_app ), kurtosis coefficient (K_app ), distributed diffusion coefficient (DDC), and intravoxel water molecular diffusion heterogeneity (α) were calculated from the corresponding non-Gaussian diffusion model. The T₁ rho value was calculated using a monoexponential model. Specimens obtained from the six timepoints were categorized into normal liver (n = 6), early-stage (n = 16), and late-stage (n = 14) SOS in accordance with the pathological score.

STATISTICAL TESTS

Parametric statistical methods and receiver operating characteristic (ROC) curves were employed to determine diagnostic accuracy.

RESULTS

The D_app , K_app , DDC, α, and T₁ rho values were correlated with pathological score with r values of -0.821, 0.726, -0.828, -0.739, and 0.714 (all P < 0.001), respectively. DKI (combined D_app and K_app ) and SEM (combined DDC and α) were better than T₁ rho for staging SOS. The areas under the ROC curve of DKI, SEM, and T₁ rho for differentiating normal liver and early-stage SOS were 0.97, 1.00, and 0.79, whereas those of DKI, SEM, and T₁ rho for differentiating early-stage and late-stage SOS were 1.00, 0.97, and 0.92, respectively.

DATA CONCLUSION

DKI, SEM, and T₁ rho may be helpful in staging SOS.

LEVEL OF EVIDENCE

2 TECHNICAL EFFICACY STAGE: 2 J. Magn. Reson. Imaging 2020;52:1110-1121.