ARRS 2022 Abstracts

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1858. Variable Size of Metastatic Liver Lesions on Dual Contrast MRI
Authors * Denotes Presenting Author
  1. Ruben Ngnitewe Massa *; University of Wisconsin Madison
  2. Frederick Kelcz; University of Wisconsin Madison
  3. Andrew Wentland; University of Wisconsin Madison
Objective:
Magnetic resonance imaging (MRI) is a commonly performed and highly accurate imaging technique for the detection of metastatic disease to the liver. Gadolinium-based contrast agents are used to improve the detection of metastatic disease. Prior studies have shown that the combined use of a contrast agent with hepatobiliary clearance, such as gadoxetate disodium (Eovist, Bayer), with a predominantly extracellular agent, such as gadobenate dimeglumine (MultiHance; Bracco), can aid in the detection of hepatic metastases. This technique relies on first injecting gadoxetate disodium, waiting until there is hepatobiliary clearance, and then injecting gadobenate dimeglumine to homogenize the signal intensity across the liver while the agent is within the vessels. Such dual contrast studies improve diagnostic accuracy, particularly for small lesions. Anecdotally, we noticed that the measured size of liver lesions can vary depending on whether the measurements were performed on hepatobiliary phase images or on images acquired following the injection of both contrast agents. The purpose of this study was to formally investigate the apparent change in size of lesions based on measurements obtained on hepatobiliary phase images versus dual contrast images.

Materials and Methods:
This was a retrospective chart review study approved by the local Institutional Review Board. A total of 21 patients (mean ± SD age, 57±11 years; 10 men and 11 women) were identified. Inclusion criteria were having a dual contrast liver MRI and having metastatic colorectal carcinoma to the liver with at least one lesion less than 2 cm. Individual lesions were treated independently. A total of 35 lesions were identified. Measurements of lesion size were performed with in-house software, which automatically computes maximum lesion size based on a 90% drop in signal intensity at the lesion edge. Measurements were performed on both hepatobiliary phase images as well as dual contrast images. A paired student’s T-test (p < 0.05) was performed to compare the measurements between the two sets of images.

Results:
The mean difference, and the mean percent difference, between measurements performed on hepatobiliary and dual contrast phase images were 0.4 ± 0.5 mm (mean ± SD; range: -0.6 to 2.2 mm) and 3.9 ± 5.2% (mean ± SD; range: -4.7 to 16%), respectively . Measurements of metastatic lesion size were significantly larger on hepatobiliary phase images than measurements performed on dual contrast images (p = 7 x 10 -5). .

Conclusion:
Metastatic colorectal carcinoma lesions to the liver measure significantly larger on hepatobiliary phase images compared to dual contrast images. Dual contrast images are ideally suited for the detection of metastatic lesions, but hepatobiliary phase images should be used for comparing lesion size over time.