Small (<20 mm) enhancing hepatic nodules seen on arterial phase MR imaging of the cirrhotic liver:: Clinical implications

OBJECTIVE. To determine the significance in patients with cirrhosis of small (<20 mm) hepatic nodules that show no hyperintensity on T2-weighted MR images but that enhance during arterial phase MR imaging, we reviewed the cases of patients with such nodules. MATERIALS AND METHODS. Our review of radiology reports yielded 68 nodules in 40 patients with cirrhosis that showed no hyperintensity on T2-weighted MR images but had rapid enhancement during arterial phase MR imaging after administration of a gadolinium contrast agent. Thirty-four patients (60 nodules) had multiple follow-up MR imaging examinations (range of length of follow-up, 1-72 months average length of follow-up, 15 months 2 weeks). The final diagnosis of the nodule was determined by pathology reports or after at least 2 years of follow-up to ensure nodule stability and, therefore, benignity. Two radiologists independently reviewed MR images of the nodules, noting the size, signal intensity on T1 or T2-weighted images, and homogeneity of contrast enhancement. RESULTS. Nine (13%) of the 68 nodules were hepatocellular carcinomas (HCCs). The size of nodules on the first MR examination was between 4 and 20 mm (mean size, 9.5 mm). No significant correlation between the diagnosis of HCC and nodule signal intensity (p = 0.48) or contrast enhancement homogeneity (p = 0,56) on first MR examination was found. Positive predictive value (PPV) and negative predictive value (NPV) for diagnosing HCC the basis of nodule growth were 100% and 98%, respectively. For diagnosing HCC on the basis of a change in nodule signal intensity, the PPV was 60% and the NPV was 91%. For diagnosing HCC on the basis of a change of enhancement homogeneity, the PPV was 63%, the NPV was 94%. CONCLUSION. A finding of growth in small, early-enhancing nodules in patients cirrhosis is highly predictive of HCC. When small nodules are observed on a single examination, close follow-up of the patient appears appropriate.