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Background and purpose Intracranial aneurysms are a known but rare complication of radiotherapy (RT). We reviewed the angiographic and clinical outcomes of intracranial aneurysms following RT in patients with nasopharyngeal carcinoma (NPC), a malignancy endemic in Hong Kong. Materials and methods The clinical, angiographic and laboratory data was collected for nine NPC patients harboring fifteen intracranial aneurysms following RT, diagnosed between 1st January 2000 and 31st December 2012. Results The median age at aneurysm diagnosis was 56 years with a male predilection (67%). The median latent period to diagnosis was nine years (0.3–30). Eight patients (89%) presented with aneurysmal subarachnoid hemorrhage. Nine aneurysms were located at the anterior circulation, and 14 were saccular in morphology. Of the treated aneurysms, eight underwent endovascular intervention and two were surgically clipped. Within a year, 50% of the treated aneurysms had recurred. Poor neurological outcome was noted. At two-year follow-up, the median score for modified Rankin score and Glasgow Outcome score was 5 and 2 respectively. The two-year mortality rate of patients with treated ruptured intracranial aneurysms was 50%. Conclusion Compared to previous studies, our irradiated NPC patients had higher mortality and morbidity rates after aneurysm rupture and a higher angiographic recurrence rate following treatment. Greater vigilance is required in the detection of post-treatment recurrence of these aneurysms due to the higher risk of rupture. The authors recommend dedicated screening of intracranial aneurysms by active surveillance in routine CT protocols or the addition of three-dimensional time-of-flight magnetic resonance angiography in MR protocols.

Objective : Several modalities are available for volumetric measurement of the intracranial aneurysm. We discuss the challenges involved in manual segmentation, and analyze the application of alternative methods using automatic segmentation and geometric formulae in measurement of aneurysm volumes and coil packing density. Methods : The volumes and morphology of 38 aneurysms treated with endovascular coiling at a single center were measured using three-dimensional rotational angiography (3DRA) reconstruction software using automatic segmentation. Aneurysm volumes were also calculated from their height, width, depth, size of neck, and assumed shape in 3DRA images using simple geometric formulae. The aneurysm volumes were dichotomized as "small" or "large" using the median volume of the studied population (54 mm3 ) measured by automatic segmentation as the cut-off value for further statistical analysis. Results : A greater proportion of aneurysms were categorized as being "small" when geometric formulae were applied. The median aneurysm volumes obtained were 54.5 mm3 by 3DRA software, and 30.6 mm 3 using mathematical equations. An underestimation of aneurysm volume with a resultant overestimation in the calculated coil packing density (p = 0.002) was observed. Conclusion : Caution must be exercised in the application of simple geometric formulae in the management of intracranial aneurysms as volumes may potentially be underestimated and packing densities falsely elevated. Future research should focus on validation of automatic segmentation in volumetric measurement and improving its accuracy to enhance its application in clinical practice.