Identification of Characteristic Findings by Abdominal Magnetic Resonance Imaging in Acute Intestinal Graft Versus Host Disease
Authors: Klein Stefan A. , Budjan Johannes , Heidenreich Daniela , Attenberger Ulrike , Kreil Sebastian , Schönberg Stefan , Hofmann Wolf-Karsten , Michaely Henrik J. 
Published: October 2019

Abstract
Abstract 4170

Introduction:
Acute graft versus host disease (aGvHD) of the gastrointestinal (GI) tract is a severe complication after allogeneic stem cell transplantation (SCT). Major differential diagnoses are infections, drug toxicity and residual effects of the conditioning. Since an early immunosuppressive treatment of aGvHD is essential a rapid and reliable differentiation between aGvHD and infections is necessary. For the first time this study describes systematically magnetic resonance imaging (MRI) findings in intestinal aGvHD.

Methods:
42 consecutive patients scheduled for allogeneic SCT were included. Prior to conditioning patients underwent as baseline investigation abdominal MRI on a whole-body 3T MR-scanner (Magnetom Skyra, Siemens) with TrueForm technology to minimize B1-inhomogeneities in the abdomen. The sequence protocol included axial and coronal T2 weighted sequences, an axial diffusion weighted sequence and a three-dimensional dynamic T1 weighted, contrast enhanced sequence. The T1 weighted sequence was performed prior application of contrast agent (0.1 mmol Gd-DOTA per kg, Guerbet) and repeated up to five minutes after the contrast injection. Per protocol all patients with severe GI-tract symptoms or with signs of skin aGvHD received a second MRI immediately after onset of clinical symptoms. In addition, all patients with severe GI tract symptoms received endoscopic examination of the upper GI-tract and colon for macroscopic and histological investigation. MRI findings of patients with histologically proven intestinal aGvHD (GvHD group) were compared with the results from patients with isolated aGvHD of the skin or non-GvHD related GI-tract symptoms (control group). Results of both groups were compared with baseline data.

Results:
Out of 42 transplanted patients eight (GvHD group) suffered from histologically proven intestinal aGvHD (median age: 60 years; underlying diseases: AML (4), MDS (2), CLL (1), multiple myeloma (1), median time after transplantation at MRI: 40 days). Seven patients were included in the control group (isolated skin aGvHD (3), CMV colitis (1), diarrhea without specific diagnosis (3), median age: 46 years; underlying diseases: AML (5), CML (1), ALL (1), median time after transplantation at MRI: 55 days). In all eight GvHD group patients unique MRI findings were detected: Diffuse ascites was present. Gut involvement presented as long-segment (>20cm) often discontinuous bowel wall thickening with profound submucosal edema of the affected bowel segments. The bowel wall was significantly thickened in patients with intestinal aGvHD in comparison with control group patients as well as with baseline data (mean large bowel wall thickness: baseline 0.35mm [range 0.27 – 0.47mm], GvHD group 0.90mm [range 0.78 – 1.12mm, p<0.001], control group 0.36mm [range 0.24 – 0.51mm]; mean small bowel wall thickness: baseline 0.38mm [range 0.22 – 0.47mm], GvHD group 0.79mm [range 0.65 – 1.11mm, p<0.001], control group 0.34mm [range 0.29 – 0.54mm]. A mucosal diffusion restriction was seen in all patients of the GvHD group. The perfusion of the bowel spared the submucosa while demonstrating strong mucosal hyperemia: In the T1 sequence two minutes after gadolinium injection a two-fold enhancement was detectable in the bowel wall of the control group as well as in unaffected bowel segments of patients with intestinal aGvHD. In contrast, the mean enhancement was 2.8-fold in small bowel wall segments affected by aGvHD.

Conclusions:
In intestinal aGvHD a characteristic MR-appearance with long-segment affection of the bowel concomitant with marked bowel wall edema, restricted mucosal diffusion, mucosal hyperemia and ascites was detected. This unique MRI pattern might facilitate an early and non-invasive diagnosis of intestinal aGvHD and exclusion of major differential diagnoses.

Disclosures:
No relevant conflicts of interest to declare.