Demonstration of Scolex in Calcified Cysticercus Lesion using Gradient Echo with or without Corrected Phase Imaging and its Clinical Implications

AIM: This study was performed to determine the magnetic resonance imaging (MRI) sequence that was best suited to demonstrate the scolex in a calcified lesion and to seek the explanation for the appearance of a negative phase in a calcified scolex on corrected gradient refocused echo (GRE) phase imaging. MATERIALS AND METHODS: Forty-nine patients with single/multiple computed tomography (CT) documented homogeneous calcified lesions and/or calcified scolices in cysts were studied with conventional spin echo and corrected GRE phase imaging. Calcium and different paramagnetic substances from cysticerci scolices of a sample of infected swine muscle were quantified. RESULTS: The scolex could be demonstrated in 29/39 patients with single calcified lesion. GRE imaging with an echo time of 35 ms was the only sequence that demonstrated scolex in all these 29 cases. 15/29 patients with a single calcified lesion, in all 10 patients with multiple calcified lesions and infected swine muscle with multiple cysts and calcified scolex, corrected GRE phase imaging showed negative phase in all these scolices. Estimation of minerals from the calcified scolices from the swine muscle showed by spectroscopic techniques 41.2% of the total mineral contents as paramagnetic substances. CONCLUSION: We conclude that GRE imaging is the imaging method of choice for demonstration of the scolex in a CT calcified lesion. The negative phase on corrected GRE phase imaging is due to the presence of large amount of paramagnetic substances. Chawla, S. et al. (2002). Clinical Radiology57, 826–834.