Multiparametric Magnetic Resonance Enterography for the Diagnosis and Staging of Intestinal Acute Graft-Versus-Host Disease after Allogeneic Hematopoietic Stem Cell Transplantation

Background: Intestinal Acute graft-versus-host disease (i-aGVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HSCT). The clinical diagnosis of i-aGVHD is usually based on symptoms and CT findings but a definite diagnosis is made by endoscopic biopsies. To date, there are few data on the use of magnetic resonance enterography (MRE) in this setting. We hereby investigated the value of MRE in the diagnosis of i-aGVHD. Methods: A retrospective observational study was carried out on 35 patients (16 men, 19 women; age 9-69 years) with hematologic malignancies who underwent a MRE for a suspect of i-aGvHD according to the Glucksberg criteria between 2015 and 2017. MRE examinations were performed with a 1.5 Tesla scanner (Siemens, MagnetomAvanto), equipped with 16-channels phased-array coils. We used a protocol including axial and coronal T2-weighted Half Fourier Acquisition Single Shot Turbo Spin Echo sequences, with and without fat saturation; T2 weighted axial and coronal TrueFISP sequences; DWI (Diffusion Weighted Imaging) sequences with b- values of 0, 500 and 1000; axial and coronal T1 weighted VIBE sequences, before and 70 seconds after the intravenous administration of contrast media (0.1 mmol gadolinium per kilogram of body weight, Gd-DOTA, Dotarem®, Guerbet, Aulnays-sous-Bois, France). In adult patients without contraindications, a 10 ml IV dose of hyoscine butylbromide was administered before contrast injection, in order to reduce motion artefacts. To evaluate the presence and severity of the disease, the following parameters were assessed and qualitatively scored for all intestinal segments (from stomach to rectum): a) MRI inflammation-activity including mural T2 signal (oedema), mesenteric T2 signal (oedema), gadolinium wall enhancement on T1 (vascularity), DWI signal (inflammation); b) morphologic parameters of activity and severity, including maximum wall thickness, increased number and/or size of local mesenteric lymph nodes, comb sign (mesenteric vessels dilation), presence of peritoneal effusion. Results: Out of 35 patients, 21 had a definite histologic diagnosis of i-aGVHD while in the remaining 14 patients i-aGVHD was excluded. The above MRE parameters were observed in 19 out of 21(90.5%) patients with a definite diagnosis of i-aGVHD and in none of the 14 patients in which a diagnosis of i-aGVHD was excluded. A stratified mucosal wall enhancement after gadolinium injection was found in 90% of patients. Parietal enhancement was associated with high-grade oedema of mesenteric fat tissue and comb sign in 76% of cases. In 52.4% of cases, mesenteric lymph nodes were not found. Free intra-peritoneal fluid was observed in 57.2% of patients. The most commonly involved intestinal segments were distal ileum (85.7%), mean ileum (66.6%) and proximal ileum (57.1%), followed by ascending colon and sigmoid equally (38%). Spearman's test showed a statistically significant correlation between clinical stage of i- aGVHD and mural T2 signal, number of involved intestinal segments, wall thickness, T1 enhancement, peritoneal effusion (p < .001). Conclusions: In our experience MRE parameters showed a good correlation with a definite i- aGVHD diagnosed and with the stage of disease. Therefore, in patients with a clinical suspect of i-aGVHD MRE examination may be considered in order to replace endoscopic biopsy to confirm the diagnosis.