Distinguishing benign from malignant liver tumours

Abstract

Liver masses are very common and most are benign. It is therefore important to avoid unnecessary interventions for benign lesions, while at the same time ensuring accurate diagnosis of hepatic malignancies. Many cancer patients, like the general population, have incidental benign liver lesions. In planning treatment for cancer patients, it is critical to avoid inappropriate treatment decisions based on misdiagnosis of a benign lesion as a metastasis or primary liver malignancy. This article describes the salient imaging features of the common benign liver masses and outlines a general approach to distinguishing between benign and malignant hepatic lesions.

Figure 1

Hemangioma. Unenhanced T2-weighted MR image (A) shows a large hyperintense hepatic mass. Gadolinium enhanced T1-weighted image (B) demonstrates the characteristic nodular enhancement at the periphery of the lesion. Reprinted with permission from Lee et al.^[132].

Figure 2

Focal nodular hyperplasia. Contrast-enhanced, arterial phase sagittal CT image (A) shows a well-defined homogeneously enhancing hypervascular mass at the inferior edge of the right lobe of the liver. Note the non-enhancing central scar. A sagittal maximum intensity projection (MIP) image (B) demonstrates early drainage of the mass into a large hepatic vein (arrowheads). An off axis coronal MIP image (C) demonstrates that the mass has two large draining veins (arrows).

Figure 3

Focal nodular hyperplasia. Unenhanced T1-weighted MR image (A) shows a nearly isointense hepatic mass (arrows) that contains a hypointense central scar. On a T2-weighted image (B) the mass is isointense, & the scar is hyperintense. Arterial phase gadolinium-enhanced image (C) demonstrates marked enhancement of the mass, except for the central scar and fibrous septa radiating from the scar. Portal venous phase image (D) shows rapid contrast enhancement washout of the lesion, which is now isointense with liver parenchyma. On a delayed postcontrast image (E) the mass remains isointense, but the central scar now is hyperintense.

Figure 4

Focal nodular hyperplasia. Arterial phase gadolinium-BOPTA enhanced image (A) demonstrates an intensely enhancing mass in segment 8 of the liver. Note the non-enhancing linear central scar. The mass is isointense on unenhanced T1-weighted (B) and T2-weighted (C) images. Portal venous phase image (D) shows rapid contrast enhancement washout of the lesion, which is now isointense with liver parenchyma. One hour delay image (E) demonstrates persistent enhancement of the mass, which is now hyperintense relative to the normal hepatic parenchyma.

Figure 5

Hepatocellular carcinoma. Arterial phase contrast-enhanced transaxial (A) and coronal (B) CT images shows a large exophytic hypervascular hepatic mass (arrow) that contains a large central scar. Arterial phase gadolinium-BOPTA enhanced MR image (C) shows similar findings. One hour delay image (D) after gadolinium-BOPTA administration demonstrates lack of enhancement of the mass. Note enhancement of the normal hepatic parenchyma (arrows).

Figure 6

Ruptured hepatocellular adenoma. Precontrast CT image (A) shows a large heterogeneous mass (arrows) near the dome of the liver. Central areas of hyperattenuation represent hemorrhage. Note the high attenuation perihepatic blood. Contrast-enhanced image (B) shows enhancement of the peripheral intact portion of the mass (black arrowheads). The hemorrhagic portion of the mass does not enhance. Note loss of integrity of the liver capsule anterolaterally. Coronal volume rendered image (C) shows the peripherally enhancing mass, ruptured liver capsule, and perihepatic blood (white arrowheads). Reprinted with permission from Lee et al.^[132].

Figure 7

Hepatocellular adenoma. In-phase T1-weighted spoiled gradient-echo MR image (A) shows a large isointense hepatic mass (M). Out-of-phase image (B) shows diffuse decrease in signal intensity within the mass due to the presence of intracellular lipid. Reprinted with permission from Lee et al.^[132].

Figure 8

Metastatic colon carcinoma. T1-weighted arterial phase gadolinium-enhanced MR image (A) shows a heterogeneously enhancing mass (arrow) in the right lobe of the liver. On an equilibrium phase image (B) the periphery of the lesion, which demonstrated enhancement during the arterial phase, is now less intense than the center of the lesion. This phenomenon is termed ‘peripheral washout’.