“…Although non-enhanced CT is known to be reliable for detection of moderate steatosis, detection on contrast-enhanced studies is limited due to variations in contrast bolus and scan timing, cardiac output, and other factors [ 6 , 8 – 11 ]. A specific examination and threshold HU could help to identify hepatic steatosis earlier and direct patients to appropriate care.…”
Section: Discussionmentioning
confidence: 99%
“…In order to compare DECT-based measurements with conventional measurements, an identical analysis was performed using the LSAD. Test characteristics (sensitivity, specificity) for diagnosing hepatic steatosis were also determined using the optimal VNC HU cut-off values as determined by ROC analysis, as well as the commonly used cut-off for LSAD of greater than − 20 HU [ 6 , 8 , 10 , 12 , 13 ]. Finally, a subgroup analysis was performed by individually evaluating examinations of each scanner type (split-beam DECT and dual-source DECT) with regard to our primary research question, which was the correlation of VNC values to MR PDFF values.…”
Section: Methodsmentioning
confidence: 99%
“…Therefore, quantitative and reliable CT-based techniques have the potential to have broad impact on patient care. When performed without intravenous contrast, CT attenuation < 48 HU is specific for mild and moderate steatosis [ 8 – 10 ]. However, contrast-enhanced CT (CECT) is more commonly performed in routine practice for a variety of clinical indications.…”
Section: Introductionmentioning
confidence: 99%
“…The presence of contrast within the liver and differences in contrast bolus timing alters hepatic attenuation and reduces the specificity of contrast-enhanced CT for hepatic steatosis [ 6 , 11 ]. Although a liver-spleen attenuation difference on CECT greater than 20 HU is specific for moderate steatosis (> 30%), specificity is much lower for mild steatosis [ 6 , 8 , 10 , 12 , 13 ]. Additionally, the presence of other materials in the liver, such as iron, may also lead to underestimation of hepatic steatosis [ 5 ].…”
Purpose
Determine whether liver attenuation measured on dual-energy CT (DECT) virtual non-contrast examinations predicts the presence of fatty liver.
Methods
Single-institution retrospective review from 2016 to 2020 found patients with DECT and proton density fat fraction MRI (MRI PDFF) within 30 days. MRI PDFF was the reference standard for determining hepatic steatosis. Attenuation measurements from VNC and mixed 120 kVp-like images were compared to MRI PDFF in the right and left lobes. Performance of VNC was compared to measurement of the liver-spleen attenuation difference (LSAD).
Results
128 patients were included (69 men, 59 women) with mean age 51.6 years (range 14–98 years). > 90% of patients received CT and MRI in the emergency department or as inpatients. Median interval between DECT and MRI PDFF was 2 days (range 0–28 days). Prevalence of fatty liver using the reference standard (MRI PDFF > 6%) was 24%. Pearson correlation coefficient between VNC and MRI- DFF was -0.64 (right) and -0.68 (left, both p < 0.0001). For LSAD, correlation was − 0.43 in both lobes (p < 0.0001). Considering MRI PDFF > 6% as diagnostic of steatosis, area under the receiver operator characteristic curve (AUC) was 0.834 and 0.872 in the right and left hepatic lobes, with an optimal threshold of 54.8 HU (right) and 52.5 HU (left), yielding sensitivity/specificity of 57%/93.9% (right) and 67.9%/90% (left). For LSAD, AUC was 0.808 (right) and 0.767 (left) with optimal sensitivity/specificity of 93.3%/57.1% (right) and 78.6%/68% (left).
Conclusion
Attenuation measured at VNC CT was moderately correlated with liver fat content and had > 90% specificity for diagnosis of fatty liver.
Graphical abstract
“…Although non-enhanced CT is known to be reliable for detection of moderate steatosis, detection on contrast-enhanced studies is limited due to variations in contrast bolus and scan timing, cardiac output, and other factors [ 6 , 8 – 11 ]. A specific examination and threshold HU could help to identify hepatic steatosis earlier and direct patients to appropriate care.…”
Section: Discussionmentioning
confidence: 99%
“…In order to compare DECT-based measurements with conventional measurements, an identical analysis was performed using the LSAD. Test characteristics (sensitivity, specificity) for diagnosing hepatic steatosis were also determined using the optimal VNC HU cut-off values as determined by ROC analysis, as well as the commonly used cut-off for LSAD of greater than − 20 HU [ 6 , 8 , 10 , 12 , 13 ]. Finally, a subgroup analysis was performed by individually evaluating examinations of each scanner type (split-beam DECT and dual-source DECT) with regard to our primary research question, which was the correlation of VNC values to MR PDFF values.…”
Section: Methodsmentioning
confidence: 99%
“…Therefore, quantitative and reliable CT-based techniques have the potential to have broad impact on patient care. When performed without intravenous contrast, CT attenuation < 48 HU is specific for mild and moderate steatosis [ 8 – 10 ]. However, contrast-enhanced CT (CECT) is more commonly performed in routine practice for a variety of clinical indications.…”
Section: Introductionmentioning
confidence: 99%
“…The presence of contrast within the liver and differences in contrast bolus timing alters hepatic attenuation and reduces the specificity of contrast-enhanced CT for hepatic steatosis [ 6 , 11 ]. Although a liver-spleen attenuation difference on CECT greater than 20 HU is specific for moderate steatosis (> 30%), specificity is much lower for mild steatosis [ 6 , 8 , 10 , 12 , 13 ]. Additionally, the presence of other materials in the liver, such as iron, may also lead to underestimation of hepatic steatosis [ 5 ].…”
Purpose
Determine whether liver attenuation measured on dual-energy CT (DECT) virtual non-contrast examinations predicts the presence of fatty liver.
Methods
Single-institution retrospective review from 2016 to 2020 found patients with DECT and proton density fat fraction MRI (MRI PDFF) within 30 days. MRI PDFF was the reference standard for determining hepatic steatosis. Attenuation measurements from VNC and mixed 120 kVp-like images were compared to MRI PDFF in the right and left lobes. Performance of VNC was compared to measurement of the liver-spleen attenuation difference (LSAD).
Results
128 patients were included (69 men, 59 women) with mean age 51.6 years (range 14–98 years). > 90% of patients received CT and MRI in the emergency department or as inpatients. Median interval between DECT and MRI PDFF was 2 days (range 0–28 days). Prevalence of fatty liver using the reference standard (MRI PDFF > 6%) was 24%. Pearson correlation coefficient between VNC and MRI- DFF was -0.64 (right) and -0.68 (left, both p < 0.0001). For LSAD, correlation was − 0.43 in both lobes (p < 0.0001). Considering MRI PDFF > 6% as diagnostic of steatosis, area under the receiver operator characteristic curve (AUC) was 0.834 and 0.872 in the right and left hepatic lobes, with an optimal threshold of 54.8 HU (right) and 52.5 HU (left), yielding sensitivity/specificity of 57%/93.9% (right) and 67.9%/90% (left). For LSAD, AUC was 0.808 (right) and 0.767 (left) with optimal sensitivity/specificity of 93.3%/57.1% (right) and 78.6%/68% (left).
Conclusion
Attenuation measured at VNC CT was moderately correlated with liver fat content and had > 90% specificity for diagnosis of fatty liver.
Graphical abstract
“…Among all these techniques, liver surface nodularity is most likely to be adopted soon given the promising results reported, rapid image processing, absence of requirement for patient fasting or for additional hardware, very low technical failure rate, and vendor-neutral results which allow applicability with all CT scanners already available. We anticipate that some of these tools will be integrated into CT workstations or PACS systems to provide multiparametric quantitative assessment of liver parenchyma [ 50 ]. Fig.…”
Over the past two decades, the epidemiology of chronic liver disease has changed with an increase in the prevalence of nonalcoholic fatty liver disease in parallel to the advent of curative treatments for hepatitis C. Recent developments provided new tools for diagnosis and monitoring of liver diseases based on ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), as applied for assessing steatosis, fibrosis, and focal lesions. This narrative review aims to discuss the emerging approaches for qualitative and quantitative liver imaging, focusing on those expected to become adopted in clinical practice in the next 5 to 10 years. While radiomics is an emerging tool for many of these applications, dedicated techniques have been investigated for US (controlled attenuation parameter, backscatter coefficient, elastography methods such as point shear wave elastography [pSWE] and transient elastography [TE], novel Doppler techniques, and three-dimensional contrast-enhanced ultrasound [3D-CEUS]), CT (dual-energy, spectral photon counting, extracellular volume fraction, perfusion, and surface nodularity), and MRI (proton density fat fraction [PDFF], elastography [MRE], contrast enhancement index, relative enhancement, T1 mapping on the hepatobiliary phase, perfusion). Concurrently, the advent of abbreviated MRI protocols will help fulfill an increasing number of examination requests in an era of healthcare resource constraints.
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