INTERESTING IMAGES Vein of Galen aneurysmal formation Case report A three-year-old child presented with delayed developmental mile- stones and seizures. On examination the head circumference was below the l O" percentile. There was no cardiac failure or bruit. PCorr FFRad C Sanyika FCRad D Royston FFflad Department of Radiology, Wentwortil Hospital & University of Natal Discussion This patient has cerebral atrophy with evidence of chronic cerebral is- chaemia resulting from the vascular steal and cerebral venous hyperten- sion. This is the chronic phase of the disorder where endovascular occlu- sion of the fistula is unlikely to im- prove symptoms. Figure te and b: CT scan pre· and post-contrast injections, demonstrated global cerebral atrophy with focal parenchymal calcification and a large central draining vein with serpiginous vessels suggesting a Vein of Galen aneurysmal malformation (VGAM) 16 SA JOURNAL OF RADIOLOGY· August 1998 Figure 2a and b: T2 weighted MR and time of flight MR confirms a central promesencephalic draining vein with a fistula arising from the anterior and posterior choroidal arteries In VGAM, the large draining vein, the promesencephalic vein, is the embryonic precursor to the Vein of Galen. I The feeding arteries are the choroidal vessels and subependymal vessels from the posterior Circle of Willis. This disorder must be differ- entiated from the Vein of Galen mal- formation, in which the Vein of Galen is well-formed.! to page 17 Vein of Galen aneurysmal forrriat iori from page 16 a common presen- tation. In the infant, presentation with macrocrania and hydrocephalus are more common. These are due to venous congestion and / or thrombo- sis. In the child de- layed developmen- tal milestones andFigure 3: Carotid angiogram confirms the fistula and draining vein of a VGAM The natural history of VGAM is variable. In the neonatal period, car- diac failure as a result of the fistula is convulsions are common, arising from the subependymal atrophy and chronic venous ischaemia.! The treatment in the neonatal pe- riod is endovascular occlusion of the fistula. From an arterial approach, the occlusion is achieved with glue and coils. A venous approach through the torcula is possible with coil occlusion, but is less favoured. References 1. Raybaud ,Strother C, Haid J. Aneurysms of the vein of Galen: embryonic considerations and anatomical features relating to the pathogenesis of the malformation. Neuroradiology 1989; 31: 109-128 2. Lasjaunis P. Vein of Galen Malformation. In: Vaswlar Diseases in Neonates, Tnfants, and Children. Publisher Springer Verlag Berlin, 1997, p 67-202 Primary hydatidosis of the thyroid gland: a case report from page 14 centre the incidence of carcinoma in patients with solitary nodules is 70%,5 compared to 17% found by McCall et al.6 We feel that the reason for this discrepancy is that at our centre we analyze the scan during both dynamic and static phases. The lesion is con- sidered malignant if a photopenic area seen on static images shows perfusion during the dynamic phase of the study. The lesion is considered benign if a photopenic area on static image shows no vascularity during the perfusion phase of the investigation. Our case displayed benign features on scintigraphy as shown on Figure 1. Evidence of diminished function in a Tc-99m scan is an indication for FNA of a nodule. Aspiration cytology showed multiple calcified bodies and very few cells, with groups of scolices resembling Echinococcus granulosus. . Should ultrasound have been performed, the potential problem of spillage could have been avoided. Ul- trasound may confirm the diagnosis of hydatid disease by demonstration of a 'cyst within a cyst' or other features.' After the left thyroid lobectomy, histological examination revealed a parasite membrane with a degener- ated germinal layer. Many degener- ated scolices and hooklets were seen with extensive dystrophic calcifica- tion. The surrounding thyroid tissue was severely inflamed with many for- eign body giant cells being seen, thus allowing a diagnosis to be made. In conclusion although our results were satisfactory,we hope that this rare case of primary hydatidosis of the thy- roid will prove useful to justify routine use of ultrasound in the evaluation of thyroid nodules, especially where a cystic lesion is suspected. With surgery still the treatment of choice, we believe that scintigraphy combined with ultra- sound prior to FNA will make the 17 SAJOURNAL OF RADIOLOGY. August 1998 surgeon aware of this possibility so as to follow the special therapeutic policy necessary to avoid dangerous spillage of the parasite. References 1. Moreno GE, Rico SP, Martinez B, et al. Results of surgical treatm nt of h patic hydatidosis: current therapeutic modifications. World] Surg 1991: 15: 254. 2. Karavias D, Vagianos C, Bouboulis N, Rathosis S, Androulakis J. Improved techniques in the surgical treatment of hepatic hydatidosis. Surg Gynaecol Obstet 1992; 174: 176. 4. Prousaltdis J, Tzardinoglou K, Sgouradis L, Katsohis C, Aletras H. Uncommon sites of hydatid disease. World] Surg 1998; 22: 17-22. 5. Rojeski MT, Gharib H. Nodular thyroid disease: evaluation and management. N Eng] Med 1985; 313:413-417. 6. Mageza RB. The role of dynamic phase pertechnetate scanning in thyroid malignant disease. South African] Surg 1994; 32: 91-93. 7. McCall A, Jarosz H, Lawr nee AM, Paloyan E. The incidence of thyroid carcinoma in solitary cold nodules and multinodular goitres. Surgery 198~lOO: 1128-1131.