Octavia Bane PhD, Presenter: Nothing to Disclose

Cecilia Besa MD, Abstract Co-Author: Nothing to Disclose

Niels Oesingmann PhD, Abstract Co-Author: Employee, Siemens AG

Hadrien Dyvorne PhD, Abstract Co-Author: Nothing to Disclose

Guido Hugo Jajamovich PhD, Abstract Co-Author: Nothing to Disclose

Bachir Taouli MD, Abstract Co-Author: Research Grant, General Electric Company Consultant, Bayer AG

Blood oxygen level dependent (BOLD) MRI measures R2* (1/T2*) of tissues, which depends on blood flow, hematocrit, and oxygen saturation of hemoglobin. This initial study quantifies baseline R2* and changes after oxygen (O2) and carbogen (CB) respiratory challenges in patients with hepatocellular carcinoma (HCC) at 1.5T and 3T.

Fat-suppressed 2D multiecho GRE sequence was acquired on the upper abdomen (at 1.5T using 5 or 12 TE’s, and 7 TE’s at 3T) in 8 healthy volunteers and 22 patients with HCC, in multiple breath-holds room air and after 10 min. of respiratory challenge. 8 subjects underwent test-retest exams. Mean R2* values at baseline, after challenges, as well as ΔR2* (%)=100x(R2*baseline-R2*gas)/R2*baseline were calculated for HCCs, liver parenchyma and muscle. A paired t-test was used to compare baseline to gas challenges R2*.

The intrasubject test-retest mean coefficients of variation for R2* measurements for air, O2 and CB for liver, HCC and muscle was <15% at 1.5T, and < 35% at 3T. There were no significant difference between liver and muscle R2* at baseline and after gas challenges. In the 30 HCCs assessed (mean size 5.8 cm, range 1-17 cm), there was no significant difference in R2* after O2 (p=0.076) or CB (p=0.1815). At 1.5T, 7 HCCs had R2* decrease post O2 (mean ΔR2*= 13%), 7 showed an increase (ΔR2*= -5.3 %), and 8 were non-responders (ΔR2*=2.1 %) (Figure). With CB at 1.5T, R2* decreased in 5 HCCs (mean ΔR2*= 15.8 %), increased in 9 (mean ΔR2*= -12.3 %), and showed no response in 1 (ΔR2*= 0.7%). At 3T, 4/8 HCCs showed a decrease in R2* with O2 (mean ΔR2* = 18 %), 3 were non-responders and 1 showed an increase (ΔR2*=-17.5%). 2 out of 3 lesions showed an increase in R2* with CB (mean ΔR2* = -25.3 %), with the same behavior reproduced at both platforms in the same HCC assessed twice (ΔR2*= -9.96% at 3T and -8.8% at 1.5T).

As shown previously, we did not observe significant change in R2* of the liver or muscle with hyperoxic challenge. HCCs demonstrated variable response to O2 and CB, which may be secondary to vascularity and hypoxia, and should be correlated to pathologic findings in this ongoing study.

R2* is a potential non-invasive biomarker of tumor hypoxia and vascularity, which has been shown to correlate with tumor invasiveness, progression and radioresistance in carcinomas.

Bane, O, Besa, C, Oesingmann, N, Dyvorne, H, Jajamovich, G, Taouli, B, Feasibility and Reproducibility of R2* Measurements under Oxygen and Carbogen Challenge in Healthy Volunteers and Patients with Hepatocellular Carcinoma at 1.5 T and 3T.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14045664.html