T2-Weighted MRI following TCPC: Fontan Patients with Type-4 Classification of the Thoracic Lymphatic Channels Show a Lower Exercise Capacity

Background: T2-weighted MRI has been recently introduced into noninvasive diagnosis of lymphatic abnormalities. According to Biko et al (Radiology 2019), patients with single ventricle physiology and greater extension and distribution of lymphatic channels in the chest and neck (type 4) showed worse outcomes on T2-weighted MRI after completion of Fontan circulation. In this study, we tried to find out if clinical and laboratory parameters are associated with type-4 abnormalities following TCPC.

Method: We prospectively examined 33 patients (22.2 years ± 8.1) after TCPC (follow-up: 17.1 years ± 8.3, mean ± SD) with a heavily T2-weighted MRI sequence on a 3.0 T scanner (MAGNETOM PrismaFit, Siemens Healthcare). Examinations in coronal orientation were performed with respiratory gating; slice thickness, 0.6 mm; TR, 2,400 ms; TE, 692 ms; FoV, 460 mm (covering thoracic and abdominal regions); and scan time (09:26–24:14 minutes) after a solid meal and a cup of pineapple juice. The findings of the lymphatic classification were correlated with parameters obtained at the annual routine check-up. Laboratory values are given in median, as in Q1/Q3. Statistical analysis was performed using two-sided U-test and Chi-square test.

Results: Eight patients (group 1) showed either unilateral or bilateral type-4 lymphatic abnormalities. Twenty-five patients (group 2) presented lower grade anomalies (types 1–3). In treadmill examination group, two reached level 7.1 ± 1.3 versus 5.4 ± 1.6 in group 1 (p = 0.006) and a distance of 731 ± 182 vs. 492 ± 181 m (p = 0.006) (mean ± SD). In the laboratory examinations, group 2 showed lower levels of NTproBNP (108; 53/193 vs. 212; 92/775 ng/L, p = 0.09), significantly lower levels of GOT (21; 16/28 vs. 32; 26/53 U/L, p = 0,004), and GPT (31; 25/37 vs. 42; 33/47, p = 0,036) as compared with group 1. Stool calprotectin was significantly lower in group 2 (24; 24/33 vs. 104 59/189 µg/g in group 1, p = 0.001). There were no significant differences in total protein, IgG, lymphocytes, or platelets. A history of ascites showed 5/8 patients in group 1 versus 4/25 patients in group 2 (p = 0.02), PLE occurred in 4/8 patient in group 1 versus 1/25 patients in group 2 (p = 0.008).

Conclusion: In the median term follow-up after TCPC, patients with lymphatic abnormalities type 4 show a lower exercise capacity and an increased rate of symptoms of imminent Fontan failure such as ascites and PLE. Further studies are required to determine the timing of evolution of these changes and their association with hemodynamic and morphologic parameters.

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Artikel online veröffentlicht:
12. Februar 2022