[A case of hypertrophic pachymeningitis].
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Dura Mater↗
Biomedical subjects
N Hirabuki
Publications and source records attributed to N Hirabuki.
Angiomyolipoma of the liver with least amount of fat component: imaging features of CT, MR, and angiography.
We report two cases of angiomyolipoma of the liver, where small amounts of fat on computed tomography, magnetic resonance imaging, and angiography made distinguishing this tumor from other hypervascular tumors difficult. Recognizing the imaging features of no capsule, hypervascularity of the tumor including the fat component, and early venous drainage may be helpful for correctly diagnosing angiomyolipoma of the liver.
Adipose Tissue↗
Computed tomographic myelography characteristics of spinal cord atrophy in juvenile muscular atrophy of the upper extremity.
Although atrophy of the lower cervical and upper thoracic cord in juvenile muscular atrophy of distal upper extremity has been reported, the atrophic patterns of the cord, especially in the transverse section, have not been studied extensively. The aim of this study is to clarify the atrophic patterns of the cord by CT myelography (CTM) and to discuss the pathogenesis of cord atrophy. Sixteen patients with juvenile muscular atrophy of distal upper extremity were examined by CTM. Atrophy of the lower cervical and upper thoracic cord, consistent with the segmental weakness, was seen in all patients. Flattening of the ventral convexity was a characteristic atrophic pattern of the cord. Bilateral cord atrophy was commonly observed; eight of 12 patients with unilateral clinical form and all four patients with bilateral form showed bilateral cord atrophy with dominance on the clinical side. There was no correlation between the degree of cord atrophy and duration of symptoms. Flattening of the ventral convexity, associated with purely motor disturbances, reflects selective atrophy of the anterior horns in the cord, which is attributable to chronic ischemia. Cord atrophy proved to precede clinical manifestations. The characteristic atrophy of the cord provides useful information to confirm the diagnosis without long-term observation.
Adolescent↗
On-off study of manganese administration to adult patients undergoing home parenteral nutrition: new indices of in vivo manganese level.
BACKGROUND: Recently, there have been reports that magnetic resonance imaging (MRI) reveals high-intensity T1-weighted images (HI) in the basal ganglia (especially in the globus pallidus) of patients receiving total parenteral nutrition (TPN). This finding is presumably due to excess administration of manganese. We investigated the reversibility and reproducibility of these changes by means of an on-off manganese administration study. We also investigated the temporal relationships between the intensity of T1-weighted images (MRI intensity) and the whole-blood and plasma manganese concentrations to evaluate the potential for the MRI intensity to serve as an index of the in vivo manganese level. METHODS: Eleven adult patients undergoing home parenteral nutrition received TPN solutions containing manganese (0 or 20 micromol/d) according to an on-off design. The whole-blood and plasma manganese concentrations were determined at the same time the brain MRI was performed. RESULTS: Both the whole-blood manganese concentration and the MRI intensity in the globus pallidus changed in response to the administration and withdrawal of manganese. It took at least 5 months for HI to disappear when manganese was withdrawn, and this change was reversible and reproducible. The whole-blood manganese concentration showed strong correlations with both the MRI intensity and the T1 value (r = 0.7693, -0.7011). The MRI intensity and the T1 value showed a strong correlation (r = -0.9051). CONCLUSIONS: The whole-blood manganese concentration, the MRI intensity in the globus pallidus and the T1 value, an objective index of the MRI intensity, may be useful indices of the manganese level in the body.
Adult↗
Asymmetric appearance of intracranial vessels on routine spin-echo MR images: a pulse sequence-dependent phenomenon.
PURPOSE: To determine the cause of right to left signal intensity differences arising from intracranial vessels during routine spin-echo axial MR imaging of the head. METHODS AND RESULTS: Using a normal imaging sequence in which the default directions of the frequency and phase axes were horizontal and vertical, respectively, differences in signal intensity arising from the vertebral arteries were observed in a healthy subject. With the exchange of the frequency and phase axes relative to the normal sequence, no signal intensity differences between the vertebral arteries were recognized. Other pulse sequence modifications, ie, the use of motion-compensating gradients and the reversed polarity of the frequency-encoding gradient, also resulted in variable appearances of the vertebral arteries, indicating that the right-to-left signal asymmetry of the vertebral arteries observed on the normal spin-echo image results from a pulse sequence dependent phenomenon. CONCLUSIONS: Frequency-encoding and slice-selection gradients both produce motion-induced phase shifts. These phase shifts depend on the angle between the direction of flow and that of the effective vector sum of these gradients. The asymmetric appearance of the vertebral arteries during normal spin-echo imaging was found to result from the angle dependence of motion-induced phase shifts. Awareness of this artifactual phenomenon is important to avoid confusing it with conditions such as stenosis/occlusion, dissection, or slow flow.
Artifacts↗
Neuromas and meningiomas: evaluation of early enhancement with dynamic MR imaging.
PURPOSE: To investigate the role of dynamic MR imaging in the differentiation of neuromas and meningiomas. METHODS: Eleven patients with neuromas and 15 patients with meningiomas underwent dynamic contrast-enhanced MR imaging using a short TE FLASH sequence and a bolus injection of Gd-DTPA. RESULTS: There was no significant difference between these tumors in the signal-enhancement increment at the late phase, which corresponds to the signal-enhancement increment between pre- and postcontrast images in conventional spin-echo imaging. However, the signal enhancement at the vascular phase, ie, the phase where the first passage of Gd-DTPA was recognized both in the arteries and veins, was approximately four times as high in meningiomas as in neuromas. The difference was statistically significant. Furthermore, meningiomas had a wider range of early signal enhancement than did neuromas, reflecting the histologic varieties: two angioblastic meningiomas had the highest values, and three fibroblastic the lowest values comparable with those of neuromas, while meningiomas with other subtypes had intermediate values. CONCLUSIONS: The results of this study indicate that the evaluation of early enhancement with dynamic MR imaging is helpful in the differentiation of neuromas and meningiomas, and possibly in the crude prediction of pathologic subtypes of meningiomas.
Contrast Media↗