Abstract

Background: Dynamic contrast-enhanced magnetic resonance imaging (DCE-MR) is becoming a widely accepted complementary method for diagnosing cancers. This technique is useful to predict and monitor the tumor response to the therapy, but it takes a longer scanning time and may not be readily available in some places. The use of dynamic contrast-enhanced ultrasound (DCE-US) is a new functional technique enabling a quantitative assessment of solid tumor perfusion in adults. Its usefulness in pediatric patients had not been determined.

Objective: To compare DCE-US curve parameters with different curve patterns of DCE-MR and assess if it can achieve the same purpose as in DCE-MR; and to explore the potential role and benefits of DCE-US in the diagnosis and treatment monitoring of pediatric extra-cranial tumors.

Methods: Children with suspected extra-cranial solid tumors, including newly diagnosed or follow-up cases of confirmed tumors, were recruited. DCE-MR was performed, and enhancement curves were plotted and categorized into type 1, 2 and 3 curves. DCE-US was then performed afterwards. Their enhancement curves and parameters were compared. The change in DCE-MR curve patterns, tumor size, predicted tumor activities and DCE-US parameters were correlated with histologic sections of the resected specimens or PET-CT in follow-up cases.

Results: There were total 26 studies, involving 17 patients (M=9, F=8) with average age 4.8 years old (range: 1-19 years old). Average scanning time was 15 minutes in DCE-US and 30-45 minutes in DCE-MR. DCE-US curve parameters correlated significantly with cases with type 3 DCE-MR curve, which had a larger slope of increase and peak intensity. For follow-up cases (n=6), DCE-MR curves changed from type 3 curve to type 1 or 2 curves in 4 cases, and there was no change in curve pattern in 2 cases. All tumors decreased in size after treatment. The slope of increase and peak intensity for DCE-US curves showed strong positive correlation with tumor size (R= 0.52 and R = 0.56). Time to peak for DCE-US curves showed strong negative correlation with tumor size (R=-0.73). DCE-MR predicted tumor activities were correlated closely with pathology or PET-CT findings (accuracy = 83.3%). DCE-US showed an increase in half-time (100%), wash-in time (83.3%) and time to peak (83.3%) in post-treatment cases, which were correlated closely with pathology or PET-CT findings.

Conclusion: US contrast is safe and easy to use in children. DCE-US curve parameters showed statistically significant correlation with type 3 DCE-MR curve, suggesting that they might have comparable utility in aggressive malignant tumors. Serial DCE-US, which has a shorter scanning time and easily available, may have a role in the monitoring of treatment response of pediatric extra-cranial tumor, resulting in more potential benefits for pediatric patients.

Keywords: Dynamic contrast; Dynamic contrast ultrasound; Extracranial tumor; Children; Pediatric