Hypoxic ischaemic brain injury

In evaluation of hypoxic ischaemic brain injury,
1. Diffusion weighted images are more sensitive than MR spectroscopy in acute setting
2. Most of the germinal matrix haemorrhage occur within 24 hours of birth
3. Cerberal cortex is more often involved in hypoxic injuries than deep grey structures in neonates and pre-term babies
4. Normal appearance on diffusion weighted images by the end of first week of hypoxic insult indicates reversal of hypoxic insults
5. Germinal matrix haemorrhage extending into ventricles is graded as IV

Answers: F, T, F, F, F

Notes: Diffusion weighted images are more sensitive than T1 and T2 weighted images, but MR spectroscopy is more sensitive than diffusion weighted images. MRS shows increased lactate in the deep gray matter, parieto-occipital region, and watershed zones as early as 2-8 hours. Germinal matrix haemorrhage is more often seen in pre-term babies born weighing less than 2000g and majority of the bleeds occur within 24 hours of birth. Deep grey structures are more often involved than cerebral cortex in both neonates and pre-term babies. Thalami, anterior vermis and dorsal brainstem are more frequently involved in pre-term babies, where as in full term neonates basal ganglia are more often involved. Diffusion-weighted images, although sensitive in diagnosing hypoxic damage, but they often underestimate the extent of the injury. Diffusion-weighted images also tend to normalise by end of the 1st week, but do not imply reversal hypoxic insult (pseuonormalization). Germinal matrix haemorrhages are graded into: Gr1 – subependymal haemorrhage without or minimal intraventiruclar bleed; gr 2 – germinal matrix and intraventricular haemorrhage without ventricular dilatation; gr 3 – gr 2 + ventricular dilatation; gr 4 – periventricular parenchymal haemorrhagic infarct

Reference: Huang BY et al. Hypoxic-Ischemic Brain Injury: Imaging Findings from Birth to Adulthood. RadioGraphics 2008;28:417-439

CNS complications in paediatric oncology

Regarding CNS complications in paediatric oncology patients,

1. Intratumoral hemorrhage is most often seen with osteosarcoma metastases.
2. Children with Wilm's tumour are at high risk of reversible posterior encephalopathy.
3. L-Asparginase, which is used in treating ALL, is associated with sinus venous thrombosis.
4. Aspergillus is the most common lethal fungal infection.
5. The dissemination of tumore via CSG occurs more frequently in paediatric age than in adults.

Answers: T, T, T, T, T

Notes:
Sarcomas are most commonly associated with intratumoral bleed in brain and osteosarcoma is the most common sarcoma to matastasize to brain in paediatric age group. Reversible posterior encephalopathy is seen in children with elevated blood pressure (on steroids), Wilm's tumor and the children on Cyclosporin-A. L-Asperginase is associated with sinus venous thrombosis. Methotrexate is associated with reversible perventricular white matter signal abnormality. Aspergillus is the most common lethal fungal infection and usually appear as intermediate signal on T2 and PD sequences; they may not show enhancement, because of lack if inflammatory response.

Reference:
Chu WCW et al. Imaging findgins of paediatric oncology patients presenting with acute neurological symptoms. Clinical radiology (2003) 58:589-603

Tuberculosis

Regarding tuberculosis,

1. Radiographic evidence of hilar lymphadenopathy is more common in adults than in children
2. Cavitation is hallmark of post-primary TB
3. In TB meningitis, abnormal meningeal enhancement is more often seen in the basal cisterns
4. In spinal TB, calcification of abscess is characteristic
5. Calcification is seen more than 50% of renal TB

Answers: F, T, T, T, T

Notes: Radiographic evidence of lymphadenopathy is more common in children (96%) than in adults (46%) and more often seen in the right hilar and right paratracheal location. Cavitation is hallmark of post-primary TB, where as lymphadenopathy is rare (5%). Calcification of abscess is highly specific of TB spine. In renal TB, calcification is seen in more than 50% and the other findings include calcyceal deformity and papillary necrosis.

Reference: Burrill J et al. Tuberculosis: A Radiologic Review. RadioGraphics 2007;27:1255-1273