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Marasco et al. Hepatoma Res 2020;6:32 I http://dx.doi.org/10.20517/2394-5079.2019.54 Page 9 of 17

in liver disease. Cirrhotic patients often develop protein-energy malnutrition (PEM), as a result of poor
dietary intake, malabsorption, increased intestinal protein loss, decreased hepatic protein synthesis,
abnormal substrate utilization and hypermetabolism [122] . Malnutrition in liver disease is also associated with
worse outcomes, increased complications and mortality [123,124] , and leads to a high prevalence of secondary
sarcopenia [125] .

2
Muscular mass can be evaluated by CT, using different methods such as calculating the area (cm ) and
density of the psoas muscle at the level of the third lumbar vertebrae, or calculating the ratio between the
muscular surface area (external and internal oblique, transverse, psoas and paravertebral muscles) and the
square of height [126] .

Recent studies have investigated the effect of sarcopenia on the morbidity of patients undergoing liver
surgery, both in cases of colon cancer metastases and of HCC. They have shown that sarcopenia is an
independent risk factor for increased post-operative morbidity [120,121,127-129] . Indeed, sarcopenia is associated
with a lower functional liver reserve; therefore, the average RLV of sarcopenic patients is statistically and
significantly less than that of non-sarcopenic patients [130] . Obese patients can also be sarcopenic if they have
[131]
increased fatty mass (BMI ≥ 30) but a loss of muscular mass . Peng et al. [121] showed that sarcopenic obesity
multiplied the risk of major complications five-fold after hepatectomy in patients with liver metastases.

In addition, on CT, is possible to calculate the intra-muscular adipose tissue content (IMAC) at the level
of L3 (i.e., IMAC = CT attenuation value of the multifidus muscles [HU]/CT attenuation value of the
subcutaneous fat [HU]). A recent paper demonstrated that muscle steatosis is associated with significantly
lower overall survival and recurrence-free survival, and it is an independent risk factor for increased major
post-operative complications in patients undergoing hepatectomy for HCC. Moreover, patients with high
IMAC are older and have a higher mass index [132] .

Another comorbidity parameter that can be evaluated with pre-operative CT scan is the bone mineral
density (BMD), which is classically defined as a “T-score”, evaluated by dual X-ray absorptiometry (DXA) of
[67]
the spine or hip. Of note, BMD has a significant negative correlation with age, especially in female patients .
Sharma et al. [133] reported BMD by measuring the CT attenuation of the trabecular bone of the eleventh
thoracic vertebral body and found that BMD < 160HU was an independent predictor of post-liver transplant
mortality in HCC patients. Miyachi et al. [134] demonstrated however, that low BMD (< 160 HU) has a strong
correlation with a poor outcome post-hepatectomy only for male patients. Thus, it is possible to utilize peri-
operative imaging parameters to assess the future liver remnant and the remnant liver volume, which are
strictly correlated with the risk of PHLF; other imaging parameters associated with both the elderly and
the health status of the patient, such as the presence of sarcopenia and low bone mineral density, are also
associated with PHLF.

Magnetic resonance imaging
Both CT and magnetic resonance imaging (MRI) show excellent accuracy and quantification of hepatic
volume [106] . Volumetry assessment by MRI is preferable to be performed on the hepato-biliary phase (HBP,
about 30 min after hepatospecific contrast agent injection). Diffusion Weighted Imaging (DWI) measures the
apparent diffusion coefficient (ADC) of water, a parameter that is dependent on tissue structure [135] . Several
reports suggest a lower ADC value in cirrhosis than in normal livers [136,137] , probably due to the restricted
-3
water diffusion in fibrotic tissue. Chuang et al. [114] reported that pre-operative liver ADC values ≤ 1.34 × 10
significantly predicted PHLF in patients undergoing hepatectomy.

The administration of hepato-specific contrast agents can help the radiologist and the clinician to evaluate the
liver’s reserve function and thus, predicts the occurrence of PHLF. Gadolinium, Gd-EOB-DTPA is a hepato-