Chunlan YANG, Juan CAO, Longping LIU, Shoujun XU
Objective To analyze the imaging features of pediatric diffuse midline glioma H3K27M variant (DMG-A). Methods The data of 22 children with DMG-A admitted to our hospital from February 2019 to October 2023 were retrospectively analyzed. Preoperative CT scan was performed in 12 cases (11 cases simultaneously with MRI). The images were independently read by two experienced pediatric imaging diagnostic doctors with over 10 years of working experience. Observed the lesion location, shape, size, density/signal characteristics of the solid part, signal intensity, restricted diffusion and MRS Manifestations, intratumoral calcification, hemorrhage and necrosis/cystic changes, enhancement features, whether there are blood vessels passing through the tumor, peritumoral edema, adjacent and secondary changes of the tumor, whether there is distant metastasis, and the metastatic site, etc. Results CT examinations were conducted in 10 cases. The brainstem lesions were mostly low/slightly low density shadows (9 cases), followed by equal or slightly high density shadows (1 case each). It is manifested as thickening of the brainstem, mostly centered on the pons, and partially involving the medulla oblongata, midbrain, cerebellar peduncle and cerebellar hemispheres. The thalamic lesion was a mass-like, uneven, slightly high-density shadow (1 case), extending towards the cisterns and the right side of the midbrain. MRI examination was conducted in 21 cases. The brainstem lesions were characterized by significant thickening and enlargement of the brainstem, with the pons being the most prominent. The main signal shadows were low on T1WI and slightly high on T2WI/FLAIR (15 cases). DWI could have diffuse limitation (9 cases), or no diffuse limitation (5 cases), and another case had no DWI examination. The lesions mostly surrounded the basilar artery (14 cases). Thalamic lesions were manifested as an increase in thalamic volume (6 cases), mainly low signal shadows on T1WI (5 cases), followed by isosignal shadows (1 case), and slightly high signal shadows on T2WI/FLAIR. DWI may have diffuse limitation (4 cases) or no limitation (2 cases). It partially affects the cerebellum, midbrain and other parts downward. After enhancement, most cases presented with obvious nodular, flower-shaped and patchy enhancement (13 cases), and could also show mild heterogeneous enhancement and no obvious enhancement (3 cases each). Additionally, 2 cases had no MRI enhancement examination. Nine cases underwent MRS Examination. The main manifestations were elevated Cho and Cr peaks, decreased NAA peak, and elevated Cho+Cr/NAA. Conclusion Although the imaging manifestations of DMG-A in children are varied, they still have certain characteristics. A comprehensive analysis of the age of occurrence, location of onset, whether the diffusion is limited, and the way and extent of intensification is helpful to improve the imaging diagnosis and differential diagnosis of the disease.