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 nonspecific inhomogenous cystic or dumbbell configuration. 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.

Primary seminal vesicle hydatidosis with exophytic component.

We report a rare case of primary seminal vesicle hydatidosis in a 47-year-old male with symptoms of pain on micturition. Computed tomography examination revealed a smooth bordered, multilocular mass-like lesion with fine septations abutting the left seminal vesicle, suggestive of hydatidosis. Pathological study of surgically excised specimen showed hydatidosis of seminal vesicle with large exophytic growth.

Unusually located osteoid osteomas.

The files of 12 patients (aged 12-33 years) with an equal number of surgically proven osteoid osteomas (OOs) were reviewed in attempt to find a diagnostic algorithm in cases of unusually located OOs. Plain radiography (PR) and thin collimation computed tomography (CT) had been performed in all patients, while bone scintigraphy (BS) had been performed in eight and magnetic resonance imaging (MRI) in two. The OOs were located at juxta- or intra-articular sites, except for one located at the left neck of the L4 vertebra. The diagnosis based on the MRI examinations was synovitis. BS showed increased accumulation of the radioisotope at the site of the lesions, without the 'double density' sign. PR showed the nidus of OO in only six patients, whereas CT located the nidus in all patients. In conclusion, we believe that when an OO is clinically suspected at an unusual location, CT should be performed in all cases, even when a lesion is depicted by PR and BS, because CT will not only locate the nidus but will also provide a precise anatomy of the area around the nidus and help in therapeutic decision making and surgical planning. MRI can be misleading and must not be used in the initial assessment of a possible osteoid osteoma.