Bhaskar Bhattacharyya1 , Amit Kumar Das2 , Arijit Roy3 , Aprateem Mukherjee4 , Tapan Dhibar5 , Kiran Sankar Saha6 , Amitabha Chattopadhyay7
BACKGROUND Chordomas are tumours presumed to originate from the remnants of embryonic notochord. They present a diagnostic challenge as they can occur in any region within the craniospinal axis and are rare with an incidence of less than 0.1 / 100,000 per year. Imaging is required for their evaluation and magnetic resonance imaging (MRI) is the imaging modality of choice due to excellent soft tissue resolution, multiplanar imaging capabilities and precise anatomical delineation. METHODS MRI scans of 10 patients, who had proven chordomas histologically, were evaluated retrospectively in the Department of Radiodiagnosis, Bangur Institute of Neurosciences from July 2012 to June 2018. Patients without histological proof of chordomas and those lost to follow-up were not included in the study. Clinical information such as age, sex, presenting symptoms were noted. Imaging parameters assessed included tumour location, bone destruction, extraspinal soft tissue component, spinal canal and neural foramina encroachment, arterial encasement, signal intensity, morphology and enhancement pattern by MRI. All the cases were scanned in a 1.5 Tesla MRI machine. Intravenous contrast were used in all cases. RESULTS Of the 10 cases, 7 were male and 3 were female. There were 7 cases of sacrococcygeal chordomas and 3 cases of clival chordomas. The tumours appeared as multilobulated masses with bone destruction. All sacrococcygeal lesions involved more than one vertebral segment with extraspinal soft tissue component encroaching the pelvic cavity and showed cystic spaces containing hypointense septae. All 3 cases of clival chordomas showed compression of the pons and basilar artery. In one case there was compression of optic chiasma with displacement of internal carotid arteries laterally. On T1 weighted imaging, the chordomas were isointense in 4 and hypointense in 6 cases. These tumours were hyperintense in T2WI in 8 and intermediate to high in signal intensity in 2 cases. All demonstrated heterogenous enhancement on contrast with moderate enhancement in 8 patients and mild enhancement in 2 cases. CONCLUSIONS Chordomas are rare tumours that can occur anywhere in the craniospinal axis. MRI is the modality of choice for imaging of chordomas. Characteristic findings in MRI include low to intermediate signal intensity on T1w images and high signal intensity on T2w images. Sacral chordomas have T2 hyperintense cystic masses with hypointense septa. Enhancement is heterogenous ranging from mild to moderate. MRI is invaluable for a pre-operative diagnosis, delineation of tumour extent and as roadmap for surgery and radiotherapy.
