Synopsis

As a non-invasive imaging technique for detecting and staging liver fibrosis, MR Elastography (MRE) is highly sensitive and specific. Conventional 2D liver GREMRE is very effective, and only takes about 1-2 minutes with multiple breath-holds (11-16 seconds, each). However, shorter acquisition times and fewer breath-holds are always desired for these examinations, especially when patients have difficulty holding their breath. In this study, we developed an 11-second hepatic MRE protocol based on SE-EPIMRE sequence, which was performed in a single breath-hold comfortably; the repeatability of repeated MRE scans was also assessed.

INTRODUCTION

As a non-invasive imaging technique for detecting and staging liver fibrosis, MR Elastography (MRE) is highly sensitive and specific (both rates: 85%-100%), using liver biopsy as a reference method ¹. Conventional 2D liver GREMRE is very effective, and only takes about 1-2 minutes with multiple breath-holds (11-16 seconds, each) ². However, shorter acquisition times and fewer breath-holds are always desired for these examinations, especially when patients have difficulty holding their breath. We have recently developed an 11-second hepatic MRE protocol based on SE-EPIMRE sequence, which requires only a single 11 second breath-hold.

Liver fibrosis is a common consequence of all liver injuries caused by hepatitis viruses (B, C), alcohol use, and/or other etiologies, and is one of the major causes of death in HIV infected people ^3-5. We tested the 11-second hepatic MRE protocol in a clinical study to determine liver fibrosis progression in HIV infected patients who use or do not use cocaine. The purpose was to evaluate the efficacy of this 11-second MRE protocol. Our hypothesis is that this protocol can be comfortably completed within one breath-hold, and that liver stiffness measurements are highly reproducible when MRE is repeated.

METHODS

11-second MRE protocol: The prototype SE-EPIMRE acquisition (11 seconds) was scanned 4 times (very-short-term test-retest) with the following major parameters: TR=1000 ms, TE = 47 or 40 ms corresponding to fractional motion encoding gradient = 100% or 80%, FOV = 42 cm, slice thickness/spacing = 6 mm/7.2mm, acquisition matrix = 100×100. Between the first two (TE = 47, 40ms) and last two MREs (TE = 47, 40ms). In addition, a VIBE Q-DIXON (5 echoes) sequence (16 seconds) was scanned for liver fat-water-ratio evaluation with the following major imaging parameters: TR = 9ms, FOV = 42/37cm, slice thickness = 3 mm, acquisition matrix = 160×140. Patients were in head-first supine position; all the scans were performed at the end of expiration on a MAGNETOM Prisma 3T scanner (Siemens Healthineers, Erlangen, Germany).

Patients: The 11-second MRE protocol was tested in the Miami Adult Studies on HIV (MASH) patients ^6,7, who are HIV-infected, HIV/HCV co-infected, HCV-mono-infected, or HIV/HCV/HBV un-infected. More than 40% MASH patients use cocaine. This study has been approved by IRB at FIU. This abstract only reports the first 11 patients; additional patients are undergoing MREs and will be analyzed as the study moves forward.

Reproducibility of MRE: intra-class correlation and Bland-Altman were analyzed between stiffness measurements with all 4 MREs by using JMP 12 Pro (Cary, NC).

RESULTS

All 11 patients completed the 11-sec MRE protocol within one breath-hold, comfortably. Fig. 1 shows examples of the 11-sec MRE images. Mean liver stiffness ranged from 1.97 kPa to 3.55 kPa. The Bland-Altman shows that the mean difference between any two MREs ranged from 0.01 to 0.09 kPa (Fig. 2). The intra-class correlation was 0.95 (1.0 means measurements were identical) among the four MREs. Fig. 3 shows examples of the fat and water images collected by using VIBE Q-Dixon. The fat-water-ratio ranged from 1% to 9%.

CONCLUSION

Acknowledgements

References

1. Huwart L, Sempoux C, Vicaut E, et al. Magnetic resonance elastography for the noninvasive staging of liver fibrosis. Gastroenterology. 2008;135(1):32-40.

2. Venkatesh SK, Ehman RL. Magnetic resonance elastography of liver. Magnetic resonance imaging clinics of North America. 2014;22(3):433-446.

3. Smith C, Sabin CA, Lundgren JD, et al. Factors associated with specific causes of death amongst HIV-positive individuals in the D:A:D Study. AIDS. 2010;24(10):1537-1548.

4. van der Helm J, Geskus R, Sabin C, et al. Effect of HCV infection on cause-specific mortality after HIV seroconversion, before and after 1997. Gastroenterology. 2013;144(4):751-760 e752.

5. Adih WK, Selik RM, Hu X. Trends in Diseases Reported on US Death Certificates That Mentioned HIV Infection, 1996-2006. Journal of the International Association of Physicians in AIDS Care. 2011;10(1):5-11.

6. Baum MK, Jayaweera DT, Duan R, et al. Quality of life, symptomatology and healthcare utilization in HIV/HCV co-infected drug users in Miami. Journal of addictive diseases. 2008;27(2):37-48.

7. Campa A, Martinez SS, Sherman KE, et al. Cocaine Use and Liver Disease are Associated with All-Cause Mortality in the Miami Adult Studies in HIV (MASH) Cohort. J Drug Abuse. 2016;2(4).