Page 12 - Read Online

Page 4 of 16 de Santis et al. Hepatoma Res 2019;5:1 I http://dx.doi.org/10.20517/2394-5079.2018.65

[20]
lower negative likelihood ratio than MDCT . However, the authors do not believe there is enough evidence
to provide definitive recommendation for systematic use of gadoxetate-enhanced MRI or extracellular
contrast-enhanced MRI over MDCT. In fact, in clinical practice, beyond the diagnostic yield, many other
factors may guide the choice between modalities, such as the presence of ascites, the patient’s inability to
hold his or her breath, the severity of cirrhosis and/or a significant hepatic iron overload, and the presence of
contraindications to the use of contrast agents.

LIVER IMAGING REPORTING AND DATA SYSTEM
The application of the guidelines in real life is often penalized by the lack of uniform terminology in
reporting and by the excessive variation in the interpretation of the exams causing the impossibility of
comparing examinations performed in different centers and/or at different times. Liver Imaging Reporting
[21]
and Data System® (LI-RADS®) was created to standardize the reporting and data collection of MDCT and
MRI for HCC. This method of categorizing liver findings for patients with risk factors for developing HCC
allows the radiology community to: (1) apply consistent terminology; (2) reduce imaging interpretation
variability and errors; (3) Enhance communication with referring clinicians; and (4) facilitate quality
assurance and research.

LI-RADS, was originally released by the American College of Radiology in 2011, and since then revised
four times. The system was created to be applied to MDCT and MRI in the context of hepatic diseases at
high risk of developing malignant lesions, such as cirrhosis, chronic hepatitis B or history of current or
prior HCC. They permit better communication between radiologists and physicians, clearly differentiating
between lesions definitively benign (LR1, i.e., LI-RADS 1), probably benign (LR2), with intermediate
probability of being malignant (LR3), with high probability of being malignant but not necessarily HCC
(LR-M), probably HCC (LR4), and definitively HCC (LR5). The final version of LI-RADS has been published
[22]
online on the American College of Radiology (ACR) website . The assignment to specific categories is
obtained considering certain “major features”: (1) arterial phase hyperenhancement; (2) size of the lesion; (3)
portal venous phase wash-out; (4) “enhancing capsule” in portal venous/delayed/transitional phases; and (5)
speed of growth over a threshold. The “enhancing capsule” is a smooth, uniform, sharp border around the
lesion, clearly thicker than the fibrous layers of the background regenerative cirrhotic nodules. The threshold
of growth means an increase in size of a mass by a minimum of 5 mm associated with: ≥ 50% increase in
size in ≤ 6 months, ≥ 100% increase in size in > 6 months or a previously unseen nodule on MDCT/MRI,
now ≥ 10 mm, in ≤ 24 months. These “major criteria” must be combined as shown below to ascertain the
final category [Figure 1]. The use of “ancillary criteria” is at the discretion of the radiologist, and allows for
recategorization [Figure 2]. In fact, one ancillary feature favoring malignancy, allows for upgrading by one
category to LR-4 (but can never be used to upgrade to LR-5); on the contrary, one ancillary criterion favoring
benignity warrants downgrading by one category; the coexistence of one criterion favoring benignity and
another favoring malignity does not modify the current category.

LI-RADS are also applicable in judging the response to treatment: even if there is no description of
treatment-specific features, some general indications are given to carry out the categorization, as illustrated
in Table 1.

Regarding the category “LR-TR viable”, when the tissue has a thick irregular aspect, the measurement is
made by taking the longest diameter of the enhancing area, without traversing the non-enhancing area;
when it has a mass like aspect (and possibly more than one mass), the biggest enhancing area is to be
measured, by taking its longest diameter.

Compared to other systems for radiological evaluation of hepatic lesions, LI-RADS has introduced an
important innovation that is a program of follow-up for each radiological category. Specifically, benign