CASE REPORT Value of MRI in paediatric closed head injury Savvas Andronikou MB BCh, FCRad (SA), FRCR (Land) Rudolf Boeddinghaus MBChB Chris J Weiman MB ChB, FCRad (SA) Department of Paediatric Radiology Red Cross Children's Hospital Cape Town Abstract Children (and less commonly adults) with a low level of conciousness fol- lowing acute head injury who have a normal CT sean are often assumed to have diffuse axonal injury of the brain. MRI may be appropriate in the sub- acute setting as it may demonstrate findings highly suggestive of such injury, as well as other findings not identified on CT. These findings may aid clinicians in determining progno- sis. We demonstrate typical findings on various MR sequences using an index case. A 2-year-old boy presented with a depressed level of consciousness (GCS 8/11) following a motor vehicle acci- dent. The CT scan performed within 6 hours showed only a small sub- arachnoid haemorrhage, with intra- ventricular extension. He remained comatose, and MRI was performed after 5 days. The T2-weighted images (Figs la and lb) showed high signal intensity in the splenium of the cor- pus callosum, at the insular grey- white interface on the left, in both temp oro-occipital regions and in the right thalamus. It also demonstrated small bifrontal subdural collections, larger on the left. Diffusion-weighted images (Fig. 2a) demonstrated increased signal (restricted diffusion) in all of the same sites, except the right thalamus. On long- TR gradient-echo (Fig. 2b), the right thalamus showed marked hypointensity in keeping with blood breakdown products. On the basis of these findings, diffuse axonal lllJury, non-haernorrhagic cortical contusions, small bifrontal subdural collections and a right thalamic haemorrhage were diagnosed. None of these was evident at CT. The patient's level of consciousness improved gradually, but he had resid- ual right hemiparesis. Shearing injuries are common in infants and young children, because the unmyelinated brain is less rigid and the subarachnoid spaces are large.I In the subacute phase, MR imaging is more sensitive than CT in detecting traumatic brain injury, such as diffuse axonal injury (DAl), non- haemorrhagic cortical contusions, haemorrhage and surface collee- tions." In DAl, T2-hyperintensity is found in typical locations (the corpus callosum, particularly the splenium and posterior body, the dorsolateral rostral brainstem, and hemispheric grey-white interfaces).' Gradient-echo images are particularly helpful in demonstrating small petechial haem- Figs 1a and b. Conventional T2-weighted imaging. (a) S~g/ttal ,,:"2W ~RI demonstrates focal high-signal les/on In the splemum of the corpus callosum (arrow) and diffuse high Signal intensity throughout the body of the corpus callosum (arrowheads). The sagittal is superior to the axial plane in showing corpus callosum abnormalities. These features are characteristic of DAl. (b) Axial T2W MRI shows ill-defined bi/ateral OCCipi- to-temporal high-signal cortical lesions (arrows) In keeping with non-haemorrhagic contusions. They were not evident on CT. 38 SA JOURNAL OF RADIOLOGY. February 2003 CASE REPORT Figs 2a and b. Special MR techniques. (a) Diffusion-weighted image demonstrates high signal over the cor- pus callosum (star) and at the left insular grey-white interface (arrowheads) in keeping with cytotoxic oede- ma. These locations are characteristic of DAl. (b) Long- TR gradient echo axial image clearly demonstrates the low signal of blood breakdown products in the right thalamus (arrow). Also demonstrated are bilateral frontal subdural col/eetions (arrowheads) that were not shown on CT. orrhages associated with DAl, with signal blooming, due to magnetic sus- ceptibility effects," Diffusion-weight- ed MR! has a role to play in distin- guishing cytotoxic oedema (in DAl) from vasa genic oedema (brain swelling).' In our patient, all the above sequences showed abnormalities, which were not evident at CT. MR! is an important prognostic tool in pae- diatric head injury. References l. Barkovich AT.Pediatric Neuronnaging. 3rd ed. Philadelphia: Lippincot Williams and Wilkins, 2000: 234-236. 2. Woodcock RT,Davis PC, Hopkins KL. Imaging of head trauma in infancy and childhood. Sernin Ultrasound CT MR 2001; 22 (2): 162- 182. 3. Kampf! A, Franz G, Aichner F, et al. The persis- tent vegetative state after closed head injury: clinical and magnetic resonance imaging find- ings in 42 patients. J Neurosurg 1998; 88: 809- 8l6. 39 SA JOURNAL OF RADIOLOGY • February 2003