Radiology Abstract Pathology affecting the suprasellar cis- tern is varied in paediatric neuroradi- ology practice. Although MRI is the imaging modality of choice for lesions of the suprasellar cistern, abnormali- ties can be detected on CT with knowledge of the normal anatomy and a sound approach to the possible pathological entities. We present our approach to pathology affecting the suprasellar cistern and highlight this using various cases seen at our institu- tion in the recent past. Introduction In modern radiology practice it is accepted that the suprasellar and sell- ar regions are best imaged using MRI.1 However, in both the First and Third- World, obtaining an MRI scan is often difficult due to the constraints of cost and availability. CT is fairly ubiquitous in modern times and is often the first imaging modality used in paediatric patients requiring neuroradiological evaluation. Pathology is often subtle on CT compared with MRI and care- ful review of images by the radiologist is necessary to make accurate diag- noses. The suprasellar cistern is an area that warrants review as it can be involved in a number of pathological processes. Our approach to pathology affect- ing the suprasellar cistern is based on the normal anatomical structures adjacent to and within it (Table I). Fig. 1 Normal suprasellar cistern on con- trast-enhanced CT showing the char- acteristic pentagonal shape.2 The ves- sels comprising the circle of Willis are clearly seen. Note the optic chiasm (long black arrow) and the contrast- enhancing normal infundibular stalk posterior to the chiasm (white arrow). 16 SA JOURNAL OF RADIOLOGY • February 2005 PICTORIAL REVIEW The paediatric suprasellar cistern as an important CT review area V Dahya MB BCh, FCRad (Diag) SA S Andronikou MB BCh, FCRad (Diag) SA, FRCR Department of Radiology University of Cape Town and Red Cross Children’s Hospital Table I. Relations and contents of suprasellar cistern and the more common paediatric pathological entities Structure Pathology Relations Inferior: pituitary gland/sella • Craniopharyngioma/ Rathke cleft cyst (embryological rests along vestigeal craniopharygeal duct) • Pituitary adenoma (rare) Superior: hypothalamus • Hamartoma • Glioma Anterior: gyrus rectus • Granuloma • Glioma Posterior: pons • Glioma Lateral: medial temporal lobes • Uncal herniation Contents Circle of Willis • Aneurysms Meninges • Inflammatory, infective or neoplastic thickening / nodularity Optic chiasm • Glioma Infundibulum/stalk • Langerhans cell histiocytosis • Germ cell tumour • Metastases Radiology 2/24/05 4:50 PM Page 16 Fig. 2 Normal suprasellar cistern seen on contrast-enhanced CT showing the normal hypothalamus within it (black arrow). Fig. 3 Craniopharyngiomas in two sepa- rate patients on contrast-enhanced CT with dense calcification within the suprasellar cistern. Solid (thin black arrow) and cystic (open black arrow) components are present in (b), with hydrocephalus. Fig. 4 A more subtle craniopharyngioma with peripheral rim calicification (white arrow) seen pre-contrast administration (a). Rim enhancement is seen post-contrast (white arrow) (b). Note that the bulk of the tumour is isodense to grey-matter. Fig. 5 Post-contrast CT showing a tuber- cinerium hamartoma. Note the non- enhancing subtle abnormality (white arrow). The child presented with gelastic seizures. Fig. 6 A pontine glioma encroaching on the posterior suprasellar cistern on contrast-enhanced CT. Note the non- enhancement of the tumour. Partial PICTORIAL REVIEW 17 SA JOURNAL OF RADIOLOGY • February 2005 Fig. 1. Fig. 2. Fig. 3a. Fig. 3b. Fig. 4a. Fig. 4b. Radiology 2/24/05 4:50 PM Page 17 18 SA JOURNAL OF RADIOLOGY • February 2005 encasement of the basilar artery (open black arrow) is an important clue to detection.3 Fig. 7 Haemorrhage from a suprasellar aneurysm on: (i) non-contrast CT and the aneurysm viewed from above on: (ii) SSD (shaded-surface display) CT angiogram of the circle of Willis (open white arrow). Fig. 8 A meningeal granuloma within the suprasellar cistern (white arrows) pre (a) and post (b) contrast. Intense post-contrast ring-enhancement is present. Microbiological studies con- firmed the diagnosis of tuberculosis. Fig. 9 A patient with confirmed tubercu- lous meningitis with intense meningeal enhancement within the suprasellar cistern (white arrow) and bilateral extension into the Sylvian fissures and the ambient-wing cisterns bilaterally. Note the complicating hydrocephalus. Fig. 10 Post-contrast CT showing a typi- cal homogeneously enhancing optic chiasm glioma (white arrow). The patient has neurofibromatosis Type One. Fig. 11 A germ-cell tumour with hyper- density of the tumour and calcifica- tion (open black arrow) pre-contrast PICTORIAL REVIEW Fig. 5. Fig. 6. Fig. 7a. Fig. 7b. Fig. 8a. Fig. 8b. Radiology 2/24/05 4:50 PM Page 18 (a) and strong enhancement post- contrast administration (b). Hydro- cephalus is also present. Fig. 12 A patient with proven tuberculous meningitis with thickening and enhancement of the infundibular stalk4 (open black arrows). Similar findings can be noted with Langer- hans-cell histiocytosis.5 Of note is that this patient did not have diabetes insipidus, which commonly occurs with infundibular stalk lesions.6 References 1. Connor SEJ, Penney CC. MRI in the differential diagnosis of a sellar mass. Clin Radiol 2003; 58: 20-31. 2. Kuuliala J. The normal suprasellar subarach- noid space in computed tomography. Clin Radiol 1980; 31: 155-159. 3. Naidich P, Zimmerman RA. Primary brain tumours in children. Semin Roentgenol 1984; 19: 100-114. 4. Manelfe C, Louvet JP. Computed tomography in diabetes insipidus. J Comput Assist Tomogr 1979; 3: 306-309. 5. Schmitt S, Wichmann W, Martin E, Zachmann M, Schoenle EJ. Pituitary stalk thickening with diabetes insipidus preceding typical manifesta- tions of Langerhans cell histiocytosis in chil- dren. Eur J Paediatr 1993; 152: 399-401. 6. Andronikou S, Furlan G, Fieggen AG, Wilmhurst J. Two unusual causes of pituitary stalk thickening in children without clinical fea- tures of diabetes insipidus. Pediatr Radiol 2003; 33: 499-502. PICTORIAL REVIEW 19 SA JOURNAL OF RADIOLOGY • February 2005 Fig. 9. Fig. 10. Fig. 11a. Fig. 11b. Fig. 12a. Fig. 12b. Radiology 2/24/05 4:50 PM Page 19