Biomedical subjects

F Mihara

Publications and source records attributed to F Mihara.

64 records · Page 4Linked to original sources

PubMedDate not supplied

Tracheobronchial calcification in members of a fixed population sample.

In a review of the chest radiographs of 1152 consecutively examined subjects, 10 cases (0.87%) of extensive tracheobronchial calcification were identified. In addition, 51 subjects having this coded diagnosis were identified among 11,758 members of a fixed population sample. Sixty of these 61 subjects were women. Tracheobronchial calcification usually appeared after the age of 60. The subjects' clinical and other radiologic diagnoses were reviewed and tracheobronchial calcification appeared to have no clinical significance. Histologic findings in autopsied cases showed the calcifications and ossifications to be in the cartilaginous rings themselves. However, the reason for the overwhelming prevalence of this entity in women remains to be resolved.

Adolescent↗

PubMedDate not supplied

Non-enhancing supratentorial malignant astrocytomas: MR features and possible mechanisms.

To clarify the MR features of supratentorial malignant astrocytic gliomas that did not exhibit contrast enhancement of MR imaging, six MR parameters were evaluated in two glioblastomas and six anaplastic astrocytomas. Moderate to marked edema, mass effect, and moderate tumor heterogeneity were noted in all cases. Hemorrhage was absent in all cases. Border definition and cyst formation or necrosis were not consistent among the tumors. Histological examination demonstrated significant vascular proliferation in two cases, and mild to moderate proliferation in six. Non-enhancing malignant astrocytic gliomas are a diagnostic challenge. Analyzing perifocal edema and heterogeneity of each mass probably provides clues for a proper diagnosis.

Adolescent↗

PubMedDate not supplied

MR imaging of adult supratentorial astrocytomas: an attempt of semi-automatic grading.

Using multiple regression analysis, six MR parameters were correlated with three histological grades among 43 proven adult supratentorial astrocytic gliomas to ascertain important MR parameters and their optimal contributions. Analysis revealed that two parameters, border definition and tumor hemorrhage, were unreliable. Using the remaining four parameters an equation was derived: Tumor grade = 0.32 (ring enhancement) +0.29 (degree of contrast enhancement) +0.13 (heterogeneity) +0.12 (edema) +0.41. Ring enhancement was the most reliable predictor of tumor grade, followed by degree of contrast enhancement. The maximum accuracies of the "semi-automatic" approach using this equation for predicting low-grade astrocytomas, anaplastic astrocytomas, and glioblastoma multiforme were 91%, 83%, and 88%, respectively. Although "semi-automatic" grading provided relatively high accuracy, possible sampling errors and some atypical cases reduced such accuracy.

Adult↗

PubMedDate not supplied

Contrast-enhanced gradient-echo MR imaging of the head and neck: experimental and clinical assessment.

To clarify the enhancement pattern of gradient-echo (GE) MR imaging, phantom experiments and 24 clinical examinations of the head and neck region were performed. Both long repetition time (TR) GE and short TR GE pulse sequences demonstrated an enhancement pattern similar to T1-weighted spin-echo imaging in phantom experiments, although the signal intensity of water and gadopentetate dimeglumine (Gd) solution was higher and the signal intensity of fat was lower with the GE technique. In clinical examinations, contrast-enhanced GE imaging was beneficial for tumors within fatty tissue, and for tumors with calcification or other magnetic susceptibility difference.

Contrast Media↗

PubMedDate not supplied

Non-T1-weighted spin-echo MR imaging with contrast material: experimental and preliminary clinical assessment.

To clarify the role of contrast-enhanced non-T1-weighted spin-echo (SE) MR imaging, phantom experiments and 20 clinical examinations were conducted. All of the SE pulse sequences demonstrated enhancement on gadopentetate dimeglumine solution phantoms. Enhancement effect was also observed on proton density-weighted and T2-weighted images in tumors. This property might be better recognized and utilized in selecting pulse sequences in routine MR examinations.

Adipose Tissue↗

PubMedDate not supplied

Intracranial metastasis of renal cell carcinoma: MR imaging.

The purpose of this study was to evaluate the magnetic resonance (MR) findings of intracranial metastatic tumors of renal cell carcinomas (RCCs). MR images of seven patients with intracranial metastases of RCCs were retrospectively reviewed. Each of the seven patients had a single lesion, including five supratentorial intraparenchymal lesions, one 4th ventricular lesion, and one pituitary lesion. Intra- and/or peritumoral flow voids were observed in five of the seven lesions. The signal intensities of the tumors were not specific. All lesions showed gadolinium enhancement, including solid (3), nearly solid (2), and ring enhancement (2). We concluded that intra- and/or peritumoral flow void is a relatively characteristic MR finding of intracranial metastases of RCCs.

Aged↗

PubMedDate not supplied

Spinal epidural venous plexus: its MR enhancement patterns and their clinical significance.

OBJECTIVE: Evaluation of the clinical utility of enhancement of the spinal epidural venous plexus (SEVP) on postcontrast MR imaging. MATERIALS AND METHODS: The SEVP on pre- and postcontrast T1-weighted sagittal and axial MR images were evaluated in 188 patients whose MR findings were abnormal (positive group), in 223 patients with normal MR (negative group), and in 35 volunteers. The enhancement patterns of the SEVP were graded 1 to 4 according to their degree of dilation. These three groups were compared and analyzed. RESULTS: Epidural and intradural lesions in the positive group showed higher grades of epidural vein enhancement compared with the negative group (p = 0.01). Epidural abscesses and epidural metastases frequently showed moderate to marked dilatation of the SEVP. Degenerative disk disease with stenosis of the spinal canal exhibited more localized patterns of dilation. Most intradural lesions with cord swelling demonstrated dilation of the SEVP. Visualization of the SEVP did not differ statistically between bone and soft tissue lesions in the positive group and the negative group (p = 0.13). Evaluation of follow-up examinations showed that changes in SEVP grades were indicative of changes in disease. CONCLUSION: SEVP enhancement patterns assist in the evaluation of disease in the spinal canal and will help to differentiate normal from pathological conditions.

Abscess↗

PubMedDate not supplied

Intra-arterial digital subtraction angiography with extra-large fields using a computed radiography system in evaluating peripheral vascular disease.

The authors evaluated the usefulness of intra-arterial digital subtraction angiography (DSA) with extra-large field sizes using a computed radiography (CR) system in evaluating peripheral vascular disease (PVD). Intra-arterial DSA using CR was performed in 55 patients with suspected PVD. A 4 F catheter was advanced into the abdominal aorta via the transbrachial approach and 90 ml of contrast medium was injected during six exposures using a long leg changer mounting a total of 18 imaging plates on six surfaces. Visualization of the superficial femoral and popliteal arteries was judged as diagnostic in all cases. The abdominal aorta, iliac arteries, and subtrifurcation were also visualized in most cases, but visualization was suboptimal in some cases. As a complication, median nerve palsy occurred in one case. This technique is thought to be a useful method for evaluating PVD because of the advantages of a large field of view and wide exposure latitude, in spite of its relatively long processing time.

Aged↗

PubMedDate not supplied

Dural non-cavernous sinus arteriovenous fistulas symptomatically simulating spontaneous carotid-cavernous fistulas: an analysis of angiographic findings.

The sites of fistulas and patterns of venous drainage in 34 consecutive cases of dural AVFs manifesting symptoms suggesting CCFs were retrospectively analyzed to determine the frequency of dural AVFs in sites other than the cavernous sinus and to ascertain their causative mechanisms. In five cases (15%), dural AVFs were demonstrated in sites other than the cavernous sinus. Among four, retrograde venous flow due to occlusion of the outflow tract or a rapid-flow shunt resulted in filling of the superior ophthalmic vein. A rapid-flow dural AVF in the anterior cranial fossa showed no occlusive changes in the sinuses, and increased pressure in the cavernous sinus was thought to be responsible for the symptoms. Embolization was effective for relief of the symptoms. Symptoms mimicking CCFs can be seen in dural AVFs in sites other than the cavernous sinus with retrograde venous drainage or with a rapid-flow shunt, conditions which are not as rare as previously believed.

Adult↗

PubMedDate not supplied

Intracranial penetrating injuries via the optic canal.

Two cases of intracranial penetration of a plastic or wooden chopstick via the optic canal are described. CT scans showed the chopsticks as linear hypodense structures in the suprasellar cistern contiguous with the optic canal. In one case, MR imaging was performed, which clearly depicted the foreign body and adjacent brain structures. Although they are extremely rare, transorbital intracranial penetrating injuries via the optic canal require physicians' awareness.

Brain Injuries↗