Recurrent vertebral hydatid disease: Spectrum of MR imaging features

Introduction: This study aimed to describe a spectrum of magnetic resonance (MR) imaging findings in a case series of four patients with recurrent vertebral hydatid disease (HD). Methods: Four patients with recurrent spinal HD, who were studied with MR imaging at 1.5T or 0.5T MR units, were encountered during a ten-year period. All patients had a history of repeated spinal surgery for hydatid resection. Results: HD involving the lumbar spine was found in two patients, the thoracolumbar spine in one patient and the lumbosacral in one patient. Skip lesions were seen in one patient. All patients had extensive involvement of the extradural space, soft tissues of the back and posterior vertebral elements. HD involving the vertebral body, intervertebral disk and iliopsoas muscles were noted in three, two and three patients, respectively. Bone and extradural hydatids were typically small, and appeared hypointense on T1-weighted images, with a mildly enhancing rim on post-contrast T1-weighted images. Sacral hydatid was an expansile multicystic process. Muscle hydatids were large, surrounded by a gadolinium-enhancing rim and assumed a variety of patterns - either multilocular or a nonspecifc inhomogenous cystic or dumbbell confguration. Conclusion: MR imaging is a valuable diagnostic tool for follow-up of patients with vertebral HD. Recurrent HD is characterised by extensive involvement of soft tissues of the back and extradural space. Extension into the intervertebral disk and iliopsoas muscles and skip lesions in the extradural space are not uncommon.