Biomedical subjects
Publications and source records attributed to Shigeru Ehara.
For staging of bone tumors, TNM and Enneking's systems are used with some differences. Magnetic resonance imaging is particularly useful for defining the extent of high-grade tumors, including transcortical and intertrabecular infiltration and periosteal extension. The concepts of compartment and curative surgical margins are important for bone tumor staging.
An 76-year-old man with an indolent soft tissue mass on the volar aspect of the left elbow was referred to our institution with a diagnosis of a soft tissue tumor. He had a history of lung tuberculosis since the age of 30. The mass was adjacent to the biceps brachi tendon. It demonstrated homogeneous low-signal intensity on T1-weighted magnetic resonance (MR) images and heterogeneous relatively high signal intensity with scattered low and high signal intensity areas on T2-weighted MR images. An excision was performed after needle biopsy with presumptive diagnosis of bicipitoradial bursitis. The histological specimen revealed an epithelioid cell granuloma with central necrosis. While the occurrence of tuberculous bicipitoradial bursitis has never been reported, this case demonstrates that it can be considered to be among the causes of a cystic lesion around the elbow joint.
We carried out an investigation to identify neuromelanin-containing noradrenergic and dopaminergic neurons in the locus ceruleus and substantia nigra pars compacta of healthy volunteers and patients with Parkinson's disease using a newly developed magnetic resonance imaging technique that can demonstrate neuromelanin-related contrast. The high-resolution neuromelanin images obtained by a 3-T scanner revealed high signal areas in the brain stem and these corresponded well with the location of the locus ceruleus and substantia nigra pars compacta in gross specimens. In Parkinson's disease patients, the signal intensity in the locus ceruleus and substantia nigra pars compacta was greatly reduced, suggesting depletion of neuromelanin-containing neurons. We conclude that neuromelanin magnetic resonance imaging can be used for direct visualization of the locus ceruleus and substantia nigra pars compacta, and may help in detecting pathological changes in Parkinson's disease and related disorders.
PURPOSE: For implantation of a catheter-port system for hepatic arterial infusion chemotherapy, catheterization via the femoral artery is occasionally difficult. The purpose of this study was to determine the usefulness of a J-type long sheath, which facilitates difficult trans-femoral catheterization. MATERIALS AND METHODS: We applied this technique to 15 patients for difficult trans-femoral catheterization for catheter-port system placement. RESULTS: We successfully implanted a catheter-port system in all patients using this technique without significant complications. CONCLUSION: We emphasize that our new technique using a J-type long sheath seems to be a reasonable option when trans-femoral catheterization is difficult.
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We present the clinical outcome of five patients who had reconstruction of large osseous defects in the iliosacral region after excision of aggressive bone tumors using pedicled-or free-vascularized iliac bone grafts. Surgical margin, incidence of recurrence and metastasis, patient survival, time to bone union, and postoperative function were evaluated. Limb-salvage surgery resulted in wide excisions in two patients with giant-cell tumors of bone and chordoma, respectively, a marginal excision in one patient with a schwannoma, and intralesional excisions to preserve nerve roots in two patients with giant-cell tumors. There was no recurrence at final followup in any of the patients. Bone union required an average of 5.4 months. The postoperative functional results were excellent in all patients except for the patient with a chordoma. In one of the patients with a giant-cell tumor, the screws and rod were removed partially because of skin necrosis in the instrumentation area. This technique is considered a good alternative for reconstruction of a large osseous defect in the pelvis because graft harvest is relatively simple and rapid, especially if a pedicled iliac bone transfer is performed.
It is very important to assess the artery of Adamkiewicz before repair of the thoracoabdominal or descending thoracic aorta. Several studies have demonstrated the feasibility and advantages of noninvasive assessment of the artery of Adamkiewicz with magnetic resonance (MR) angiography and multi-detector row computed tomographic (CT) angiography. Recent advances in MR angiography and CT angiography have led to changes in the detectability of this artery. In the present study, both MR angiography and CT angiography were performed without complications for preoperative evaluation of 30 patients who underwent repair of the thoracoabdominal or descending thoracic aorta. MR angiography provided detection rates as high as 93% and 80% with the morphologic "hairpin turn" criterion and the anatomic "continuity" criterion, respectively. Sixteen-detector row CT angiography provided detection rates as high as 83% and 60%, respectively. Use of both MR angiography and CT angiography provided higher detection rates of 97% and 90%, respectively. The collateral pathways were depicted in seven cases (23%). MR angiography is superior for depiction of the artery of Adamkiewicz, especially when it arises from the false lumen of a dissecting aneurysm. CT angiography has a wide field of view and allows depiction of significant collateral pathways associated with the internal thoracic artery and intercostal arteries.
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We report a case of stress fracture of the clavicle associated with sternocostoclavicular hyperostosis. A 60-year-old man sustained a stress fracture of the right clavicle with no history of trauma. On radiography, hyperostosis of the anterior chest wall and ankylosis of the sternoclavicular joint were evident in addition to the fracture. Fracture healing was uneventful after 2.5 months. Ankylosis of the sternoclavicular joint may have caused increased stress at the midshaft of the clavicle by daily activity or minor trauma. Such a fracture is a rare complication of sternocostoclavicular hyperostosis.
We report a 16-month-old boy with human herpes virus-6 (HHV-6) encephalopathy showing transient abnormalities of the cerebral white matter on magnetic resonance imaging. Diffusion-weighted imaging (DWI) demonstrated diffuse high signal intensity in the bilateral cerebral white matter areas. The signal changes on DWI subsequently resolved, and cerebral atrophy resulted. The transient decrease in the cerebral white matter diffusivity seen in the present case may reflect axonal involvement secondary to the glial or neuronal damage in HHV-6 encephalopathy.
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PURPOSE: To investigate the difference in enhancement effects and relaxivities of the gadolinium chelate at 1.5 and 3 Tesla (T) and to elucidate the contribution of the high magnetic field to contrast enhancement in spin-echo (SE) and gradient-echo (GRE) images. METHODS: Phantoms containing water with or without gadopentetate dimeglumine (Gd-DTPA) at different concentrations were scanned using 1.5T and 3T MRI scanners of the same manufacturer and under the same temperature conditions and scanning parameters. Relaxivities of gadolinium, R1 and R2, were estimated from serial T1 and T2 values of the phantoms using linear regression. Contrast enhancement ratios in SE and GRE T1-weighted images were compared at 1.5 and 3T. RESULTS: The R1 and R2 of Gd-DTPA at 1.5 and 3T were 4.79 and 5.14, and 4.50 and 5.09, respectively. Although the relaxivities at 3T were slightly lower than those at 1.5T, the contrast enhancement ratio improved in both SE and GRE images as a result of T1 prolongation of the water at 3T. CONCLUSION: The decrease in relaxivities of the Gd-DTPA at 3T appears to be so small that T1 prolongation of the water improves contrast enhancement, suggesting a potential clinical advantage in administration of Gd-DTPA at high field strength.
Intraoral neurilemmoma is rare (only 1%), and the most common form is a unilobular tumor on the dorsum of the tongue in the patients in the 2nd and 3rd decades of life. Herein we describe the case of intraoral neurilemmoma in a 9-year-old girl complaining only of a sore throat. She had an exophytic multilobulated mass on the base of the tongue. MR imaging demonstrates the extension of the tumor and helps in the differential diagnosis. The signal intensity of the tumor is similar to that of neurilemmomas in the other sites.
A 73-year-old woman with liver metastasis underwent implantation of an infusion catheter-port system for hepatic arterial infusion chemotherapy. She developed multiple infarctions caused by disseminated intravascular coagulation (DIC) due to liver metastases. The hypercoagulability syndrome associated with cancer (known as Trousseau's syndrome) is considered a cause of cerebral infarction. Among the complications of the implantation of an infusion catheter-port system, Trousseau's syndrome may be one of the causes.
We investigated hippocampal substructure in the rat, cat, dog, and human by means of magnetic resonance imaging to elucidate phylogenetic differences in longitudinal organization. Multidirectional high-resolution images obtained with a 3 T scanner revealed that the dorsal part of the hippocampus was well developed in the rat, cat, and dog brain, and was homologous to the hippocampal tail, a poorly-developed posterior part, in the human. We conclude that the dorsal hippocampus of laboratory animals corresponds to the hippocampal tail in the human brain, which is considered to be hypoplastic and of less importance clinically than more anterior regions. These data may help in understanding phylogenetic, and in correlating results from animal experiments with clinical findings on the functions and pathologies of the human hippocampus.