Dual Energy Spectral CT of Focal Liver Lesions in Advanced Cirrhosis: Early Experience William P. Shuman MD, FACR University of Washington SCBTMR Annual Course Washington DC, October 23-26, 2011
Conflict of Interest Statement I administer a grant from GE Healthcare which supports clinical investigations in body CT No support for equipment or salaries
Model for End-stage Liver Disease MELD Score (6 40 points) Mayo Clinic 2000 Used to stratify patients waiting for liver transplant by medical urgency Based on lab data creatinine, tot. bilirubin, ratio
Model for End-stage Liver Disease MELD Score (6-40) No exception for stage 1 HCC (< 2cm) Exception for patients with stage T2 HCC Granted 24 extra points Goal: Waiting time for HCC = non-hcc Drop-out rates equal
UCSF-Expanded MELD Criteria Now (2010) includes Stage 3a by CT imaging criteria - hypervascular lesion in patients with end stage liver disease: Single lesion < 2 cm 6.5 cm 2-3 lesions each 4.5 cm total lesion diameter 8 cm No macrovascular invasion on CT Pomfret EA, Liver Transpl 2010; 16:262
Single Energy CT Early detection of small lesions is imperfect MR sensitivity outperforms CT by 10 15% Characterization of small lesions into cyst versus small tumor is difficult HU unreliable due to partial volume
Dual Energy: Potential Liver Applications Enhance the subtle lesion Tumor versus cyst Eliminate unenhanced phase Focal fat, Iron deposition Response to Y-90
Dual Energy Liver CT: History First published in 1980, Brit. Med. J. R.W.G. Chapman and Gram Bydder Dual Energy CT for liver iron content in hemochromatosis EMI 5005 140 and 110 kvp 20 seconds per slice CT estimates of iron content correlated closely with chemical analysis of biopsies
Dual Energy Liver CT: 2008 R. Nelson, MDCT, Las Vegas, 5/15/08
Dual Energy Liver CT: 2009 80 kvp 140 kvp D. Marin et al, Radiology, 2009
Dual Energy: The Big Questions Might late-arterial stage dual energy CT in patients with end stage liver disease improve hypervascular lesion (HCC) - Conspicuity of individual lesions Number of lesions detected Accuracy of measurements Characterization of lesions (washout)
DECT of Hypervasc. Liver Lesions 40 patients with HCC, 135 lesions (2011) 80 kvp 140 Averaged Mean # lesions 3.37 1.43 2.57 Total # lesions 135 57 103 HU (ave) 119 78 92 CNR 6.4 4.7 6.9 Image Quality poor fair excellent Altenbernd A, et al, Eur Radiology 2011 21: 738
Dual- vs. Single- Energy CT: Dose University of Washington experience: GE HD 750 with GSI CT of liver Single: ACTM NI=36, ASIR 40% DE GSI: ACTM NI=25, ASIR 30% (Fixed) Dual energy runs 15% higher dose than our routine clinical scanning (NI = 36) But user variable ASIR % coming
kev 140-40
Dual Energy Spectral Imaging: HCC Water only Iodine only
Dual Energy Spectral Imaging: HCC 70 kev
Dual Energy Spectral Imaging: HCC 40 kev 130 kev
Dual Energy Spectral Imaging: HCC 40 kev 60 kev
Dual Energy Spectral Imaging: HCC Water Only Iodine Only
Dual Energy Spectral Imaging: HCC 40 kev 110 kev
Dual Energy Spectral Imaging: HCC 40 kev 80 kev
40 kev 67 kev 50 kev 77 kev
Spectral GSI and Portal Venography 30 patients with portal hypertension 140 monochromatic plus polychromatic image sets Objective CNR and subjective image quality Optimal CNR at 51 kev 100% higher contrast than 120 kvp but 30% more noise Subjective image quality scores statistically best at 51 kev Zhao et al, Euro J. Radiol, 2011
51 kev 120 kvp Zhao et al, Euro J Radiol 2011
kev vs. CNR of Iodine : 51 kev Portal Vein (Zhao, EJR) Hypervasc. Liver Lesion (Mitsumori)
40 kev 51 kev 70 kev 77 kev
Hypodense Liver Lesions: Met vs. Cyst GSI Projection Based Dual Energy Hypodense Liver Lesions Santamaria-Pang, Hara, et al, Proc SPIE, 2010
Liver Fat Distribution and Quantification GSI Projection Based Dual Energy Kriston, Silva, Sahani, et al, SPIE 2010
Conclusion Dual energy spectral CT images of the liver show promise for improving focal lesion detection and characterization in cirrhosis. Impact on lesion staging - research Optimal kev may improve sensitivity May lead to earlier tumor detection May improve characterization of lesions