MRI of lumbar and sacral plexus nerve sheath tumours

Perianal pain as a presentation of lumbosacral neurofibroma: a case report

Rectal and perianal pain is a common problem. Most people have experienced it at least once in their lifetime. It usually manifests as mild discomfort, but sometimes the pain can be so severe that it is incapacitating. A 59-year-old woman admitted with a 2-year history of paroxysmal perianal pain underwent a full work-up including proctoscopy, sigmoidoscopy, full colonoscopy, and barium enema that were unremarkable. Lumbosacral magnetic resonance imaging with and without gadolinium showed an intradural-extramedullary lesion at the level of L5. The pathologic diagnosis was a neurofibroma. She underwent surgery, and after a few weeks she felt well and medication was no longer needed for her paroxysmal pain. Although one should consider the usual causes of colorectal pain such as hemorrhoids, anal fissure, proctalgia fugax, and chronic perianal pain syndrome, we should keep in mind that some referral pain may mimic local pathologies and should be evaluated properly.

Pelvic radiculopathies, lumbosacral plexopathies, and neuropathies in oncologic disease: a multidisciplinary approach to a diagnostic challenge

The purpose of this article is to familiarize the reader with the anatomy of the major pelvic nerves and the clinical features of associated lumbosacral plexopathies. To demonstrate this we illustrate several cases of malignant lumbosacral plexopathy on computed tomography, magnetic resonance imaging, and positron emission tomography/computed tomography. A new lumbosacral plexopathy in a patient with a prior history of abdominal or pelvic malignancy is usually of malignant etiology. Biopsies may be required to definitively differentiate tumour from posttreatment fibrosis, and in cases of inconclusive sampling or where biopsies are not possible, follow-up imaging may be necessary. In view of the complexity of clinical findings often confounded by a history of prior surgery and/or radiotherapy, a multidisciplinary approach between oncologists, neurologists, and radiologists is often required for what can be a diagnostic challenge.

Causes of lumbosacral plexopathy

The lumbosacral plexus represents the nerve supply to the lower back, pelvis and legs. This review will focus on diseases and disorders affecting the pathway as demonstrated by magnetic resonance imaging (MRI) and computed tomography (CT). We stress the need to review the lumbosacral plexus in patients with non-specific symptoms such as back, hip, pelvic pain, and in those who present with sciatica unaccompanied by demonstrable intervertebral disc prolapse. We illustrate that the imaging appearances may be non-specific and re-inforce the importance of the clinical history and the use of tissue sampling to achieve an accurate diagnosis.

The spine

Computed tomography (CT) and magnetic resonance imaging (MRI) are becoming increasingly accessible in veterinary medicine. Because of their ability to image the bony spine and spinal cord noninvasively and with exceptional detail, these techniques have revolutionized the way spinal disorders are diagnosed in both people and animals. Although the veterinary literature on this topic is limited, interpretation of CT and MR images of the spine are facilitated by the similarity of human and animal disease processes. This article provides an overview of imaging strategies, normal anatomy, and the CT and MRI features of degenerative, infectious, neoplastic, and vascular diseases of the spine.

MR imaging differentiation of benign and malignant peripheral nerve sheath tumors: use of the target sign

BACKGROUND

T2-weighted MR imaging of soft tissue tumors of neural origin may show round lesions with a central hypointensity and a hyperintense rim resembling a target. We define the "target sign" as a mass consisting of a solitary target, or a multicompartmental mass in which the largest component consists of multiple targets.

OBJECTIVE

The objective of this study was to determine whether the target sign can differentiate benign neurofibromas and their malignant counterparts, malignant peripheral nerve sheath tumors. Materials and methods. Preoperative T2-weighted MR images of 23 neurofibromas or malignant peripheral nerve sheath tumors were retrospectively reviewed in 16 patients, aged 3 weeks to 20 years (median 15 years), without knowledge of the pathologic diagnosis. The presence or absence of a target sign was noted.

RESULTS

The target sign was seen in all 12 neurofibromas and 1 of the 11 malignant peripheral nerve sheath tumors. Statistical analysis showed good differentiation of benign and malignant tumors using this sign (chi = 0.91).

CONCLUSION

The target sign on T2-weighted MR imaging is helpful in differentiating neurofibromas from malignant peripheral nerve sheath tumors.

Magnetic resonance neurography of peripheral nerve lesions in the lower extremity

OBJECTIVE

We describe the clinical application and utility of high-resolution magnetic resonance neurography (MRN) techniques to image the normal fascicular structure of peripheral nerves and its distortion by mass lesions or trauma in the lower extremity.

METHODS

MRN images were obtained using a standard 1.5 Tesla magnet and custom built phased-array coils. Patients were imaged using T1-weighted spin echo without and with gadolinium, T2-weighted fast spin echo with fat peripheral nerve tumors (three neurofibromas and one schwannoma), two with intraneural cysts, and three with traumatic peripheral nerve lesions. Six patients with peripheral nerve mass lesions underwent surgery, thereby allowing MRN images to be correlated with intraoperative and pathological findings.

RESULTS

Preoperative MRN accurately imaged the normal fascicular anatomy of peripheral nerves and precisely depicted its relation to tumor and cystic lesions. Increased signal on T2-weighted fast spin-echo and short tau inversion recovery fast spin-echo pulse sequences was seen in the peripheral nerve fascicles of patients with clinical and electrodiagnostic evidence of nerve injury.

CONCLUSION

MRN proved useful in the preoperative evaluation and planning of surgery in patients with peripheral nerve lesions.

Ganglioneuroma: computed tomography and magnetic resonance features

12 patients who had histological proven ganglioneuromas were investigated by computed tomography (CT) and magnetic resonance (MR) imaging. CT scans (n = 11), conventional spin-echo MR images (n = 10) and dynamic MR images (n = 5) were acquired. All lesions showed a well defined, oval shape. Five lesions (42%) showed calcification which was punctate in four and coarse in one on CT. CT attenuation was predominantly low in three of 10 (30%) and intermediate in the remaining seven (70%). In all lesions MR signals were mainly of low intensity on T1 weighted images (T1WI) and of high intensity on T2 weighted images (T2WI). Dynamic MR studies in five cases showed a lack of early enhancement but gradual increasing enhancement. One case had a ganglioneuroblastoma component which showed soft-tissue density and coarse calcifications on CT scans, MR images with intermediate intensity on T1WI and T2WI and early enhancement and little washout on dynamic MR images. In conclusion, ganglioneuroma typically shows punctate calcification and low attenuation on CT and marked hyperintensity on T2WI with gradual increasing enhancement on dynamic MR images. If a ganglioneuroma has atypical CT and MR features, coexistence of a malignant component should be considered.