Keiko Nakayama

Syringomyelia associated with adhesive spinal arachnoiditis: MRI

Abstract We reviewed the MRI of seven patients with syringomyelia associated with surgically proven adhesive spinal arachnoiditis to describe clinical and MRI findings in this condition. Using 0.5, 1.0 or 1.5 tesla units, we obtained sagittal T1- and T2-weighted spin-echo and axial T1-weighted images. Additional sagittal T2-weighted images were obtained without using motion-artefact suppression. Contrast medium was given intravenously to five patients. The syrinx cavities were thoracic in five cases, cervicothoracic in one, and extended from C4 to L1 in one. No Chiari malformation or craniovertebral junction anomaly was demonstrated. Meningeal thickening was seen on T2-weighted sagittal images only in one case. Cord deformity due to adhesion or displacement due to an associated arachnoid cyst was seen in all cases best demonstrated on axial images. Focal blurring of the syrinx wall on axial images was seen in six patients. Flow voids were seen in the syrinx fluid in all cases on T2-weighted images obtained without motion-artefact suppression. No abnormal contrast enhancement was demonstrated.

Retrospective review: Usefulness of a number of imaging modalities including CT, MRI, technetium-99m pertechnetate scintigraphy, gallium-67 scintigraphy and F-18-FDG PET in the differentiation of benign from malignant parotid masses

ObjectiveThe aim of this study is to evaluate an imaging approach using computed tomography (CT), magnetic resonance imaging (MRI), technetium-99m pertechnetate scintigraphy (99mTc pertechnetate scintigraphy), gallium-67 scintigraphy (67Ga scintigraphy) and fluorine-18 fluorodeoxyglucose positron emission tomography (18F-FDG PET).Material and MethodsWe reviewed retrospectively 59 patients with parotid masses. CT, MRI,67Ga scintigraphy,99mTc pertechnetate scintigraphy, and18F-FDG PET were performed.ResultsAll of the benign tumors had smooth margins on CT and MRI. Patients with inflammatory lesions and malignant lesions showed well-defined margins or ill-defined margins. All Warthins tumors showed high technetium accumulation. Many of malignant tumors showed high FDG accumulation. Both pleomorphic adenomas and Warthins tumors showed high accumulation in some cases on18F-FDG PET. Among 15 patients with pleomorphic adenoma, 14 patients showed marked hyperintensity relative to CSF on T2-weighted images and partial enhancement on contrast-enhanced T1-weighted images. Combination of several imaging modarity offered usefulness of differential diagnosis for parotid masses.ConclusionAn efficient combination of imaging methods may be helpul for achieve the correct diagnosis.

Neurofibromatosis Type 1 and Type 2: review of the central nervous system and related structures

Although computed tomography (CT) provides a major imaging advance over conventional radiography and tomography in examining the whole body, the development of magnetic resonance (MR) imaging has proven to be an even greater breakthrough in diagnostic medical imaging. The anatomic detail demonstrated in a MR image is a representation of at least three physical properties of static-tissue: proton density, and T1 and T2 relaxation times. Intrinsic differences in proton density and, in particular, in proton relaxation times of tissues allow excellent image contrast between various normal structures and high sensitivity in detecting pathological states. This article discusses imaging features of neurofibromatosis, with particular emphasis on the potential of MR imaging.

Glucocorticoid treatment of brain tumor patients: changes of apparent diffusion coefficient values measured by MR diffusion imaging

Glucocorticoids (GCC) generally are administered to patients with brain tumors to relieve neurological symptoms by decreasing the water content in a peritumoral zone of edema. We hypothesized that diffusion imaging and apparent diffusion coefficient (ADC) values could detect subtle changes of water content in brain tumors and in peritumoral edema after GCC therapy. The study consisted of 13 patients with intra-axial brain tumor, and ADC was measured in the tumor, within peritumoral edema, and in normal white matter remote from the tumor before and after GCC therapy. ADC also was measured in normal white matter in four control patients with no intracranial disease who were treated with GCC for other indications. Conventional MR images showed no visually evident interval change in tumor size or the extent of peritumoral edema in any subject after GCC therapy, which nonetheless resulted in a decrease in mean ADC of 7.0% in tumors (P<0.05), 1.8% in peritumoral edema (P>0.05, not significant) and 5.8% in normal white matter (P<0.05). In patients with no intracranial disease, GCC therapy decreased mean ADC in white matter by 5.4% (P<0.05). ADC measurement can demonstrate subtle changes in the brain after GCC therapy that cannot be observed by conventional MR imaging. Measurement of ADC proved to be a sensitive means of assessing the effect of GCC therapy, even in the absence of visually discernible changes in conventional MR images.

MR imaging of a case of a dumbbell-shaped spinal schwannoma with intramedullary and intradural-extramedullary components

Abstract We present here a case of intramedullary- and extramedullary-intradural, dumbbell-shaped schwannoma that developed in the upper thoracic cord in a middle-aged man. Before surgery, the tumor was clearly revealed as a mass with two components, intramedullary and extramedullary, on MRI, and it could be useful for operation. We discuss the possible pathogenesis of this tumor.

The "botryoid sign": a characteristic feature of rhabdomyosarcomas in the head and neck.

Abstract We investigated nine patients with rhabomyosarcoma in the head and neck (6–53 years of age), using CT and MRI. The tumours originated in the paranasal sinuses (3), cheek (2), soft palate (1), orbit (1), sternocostoclavicular muscle (1) and parapharyngeal space (1). The histological subtype was embryonal in five, alveolar in three and pleomorphic in one case. The tumours enhanced markedly and heterogeneous on CT and MRI. The masses were isointense or gave slightly higher signal than surrounding muscles on T1- and heterogeneously high signal on T2-weighted images. In four tumours, multiple ring enhancement resembling bunches of grapes. This appears to be characteristic of rhabdomyosarcoma and probably reflects a component of botryoid-type rhabdomyosarcoma in which mucoid-rich stroma is covered with a thin layer of tumour cells. We have named this imaging feature the “botryoid sign”.

Supratentorial convexity leptomeningeal schwannoma: Case report

OBJECTIVE AND IMPORTANCE Leptomeningeal schwannomas are very rare; to our knowledge, only one case has been previously reported. The possible histogenesis and differential diagnosis of intracranial schwannomas not related to cranial nerves are discussed. CLINICAL PRESENTATION A 53-year-old man presented with a sudden onset of seizures. Computed tomographic scans revealed a small hypodense mass in the peripheral aspect of the left frontal lobe. The mass was hypointense on T1-weighted and hyperintense on T2-weighted magnetic resonance imaging scans, with ring enhancement after contrast medium administration. INTERVENTION A craniotomy was performed for total removal of the tumor, revealing a well-demarcated, firm, spherical tumor beneath the dura. The tumor was easily separated from the brain. Histologically, the tumor was observed to be within the subarachnoid space, intimately attached to the pia mater. The adjacent brain tissue and dura mater were free of tumor cells. The histological diagnosis was schwannoma. CONCLUSION Computed tomographic and magnetic resonance imaging findings in our case were consistent with those for a schwannoma, although the subarachnoid space is an extremely rare location for schwannomas. We emphasize that schwannomas may arise in the subarachnoid space.

False-positive magnetic resonance imaging skeletal survey in a patient with sporadic hypophosphatemic osteomalacia

Oncogenic osteomalacia (OOM) is a rare disease characterized by renal phosphate wasting and osteomalacia [1]. More than 100 patients have been reported to have rickets and/or osteomalacia induced by various types of tumors [2]. As clinical symptoms associated with hypophosphatemia or osteomalacia improved or completely disappeared on removal of the tumors, an unknown phosphaturic factor was believed to play an important role in the development of OOM [3–6]. Detection of the responsible tumor has great importance; however, there has been no standard method. Magnetic resonance (MR) imaging is reported to be a useful method for the diagnosis of bone and soft tissue tumors. Many groups successfully discover the lesion of the responsible tumor by MR imaging [7–10]. Especially, MR imaging was the only technique to point out the responsible tumor in some cases because plain roentgenograms and X-ray computed tomography (CT) did not contribute to finding the tumors [7,8]. After successful removal of these tumors, the biochemical abnormalities such as hypophosphatemia were normalized, indicating that the tumors were responsible for the disease. We describe herein a case of false-positive MR imaging of a responsible tumor inducing osteomalacia, and discuss the limitations of diagnosis by MR imaging. Case report