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Biomedical subjects

M Mitomo

Publications and source records attributed to M Mitomo.

At least 19 recordsLinked to original sources
PubMed1992

Pseudoenhancement of intervertebral disc herniation.

Two patients with intervertebral disc herniation appeared to demonstrate abnormally diffuse and intense enhancement of the disc after intravenous administration of gadolinium-DTPA for MRI. Surgery disclosed a dilated epidural venous plexus in one and vascular granulation tissue in the other, associated with the herniated disc material. The mechanism of this "pseudoenhancement" of the disc appears to be a partial volume effect of disc material and the adjacent veins or granulation tissue. Pseudoenhancement of a herniated disc should be included in the differential diagnosis of a diffusely enhancing epidural mass.

Aged↗
PubMed1992

Follow-up MRI in dural arteriovenous malformations involving the cavernous sinus: emphasis on detection of venous thrombosis.

Six patients with a dural arteriovenous malformation (dural AVM) involving the cavernous sinus were followed up with magnetic resonance imaging in order to assess change in the lesions. Spin-echo (SE) imaging of three patients in whom the AVM appeared to have closed at least 1 month earlier (two of them spontaneously, and one after external carotid artery embolization) showed neither apparent flow void in the involved cavernous sinus nor evidence of venous thrombosis. SE images of the other three patients who had not been cured by external carotid artery embolization (two of whom were examined within a week of treatment), detected persisting arteriovenous shunts, including high-flow cortical venous drainage, seen as flow void. Two-dimensional time-of-flight MR angiography (2D TOF MRA) was performed simultaneously in three patients. Whereas shunting blood and the normal cavernous sinus were of high intensity, presumed thrombosed cavernous sinuses were isointense with stationary brain tissue. SE imaging can confirm the resolution of arteriovenous shunts, but poorly delineates very acute and chronic thrombosis of the draining veins. In contrast, 2D TOF MRA directly demonstrates flowing blood, permitting the diagnosis of venous thrombosis; it should be included in follow-up of a dural AVM involving the cavernous sinus when venous thrombosis is suspected.

Adult↗
PubMed1992

MR diagnosis of meniscal tears of the knee: value of axial three-dimensional Fourier transformation GRASS images.

Axial MR images of 40 knees in 37 patients with clinically suspected meniscal tears were obtained by using a three-dimensional (3-D) Fourier transform, gradient-refocused acquisition in the steady state (GRASS) pulse sequence. All knees also were examined in both coronal and sagittal planes with a two-dimensional (2-D) Fourier transform, spin-echo pulse sequence for T1-weighted images and a multiplanar GRASS pulse sequence for T2*-weighted images (conventional 2-D pulse sequences). Arthroscopic confirmation was available in all cases and was used as the gold standard. In these 40 knees, 32 of 33 meniscal tears and 45 of 47 normal menisci were correctly identified with axial 3-D imaging, yielding a sensitivity of 97% and specificity of 96%. Conversely, the sensitivity was 82% and the specificity was 100% for the 2-D technique in the diagnosis of meniscal tears. A combination of both techniques yielded 100% sensitivity, 100% specificity, and 100% accuracy in the evaluation of the menisci. Seven discrepancies between the findings of the two techniques were found in the evaluation of 33 arthroscopically proved torn menisci; six of the seven represented false-negative 2-D images and one was a false-negative axial 3-D image. Of 47 normal menisci, only two false-positives occurred with axial 3-D imaging and none with 2-D imaging. Despite the lack of a statistically significant difference, these preliminary findings suggest that the sensitivity in the diagnosis of meniscal tears can be improved by adding thin-sliced axial images with the 3-D GRASS pulse sequence to conventional 2-D imaging.

Adolescent↗
PubMed1991

[Three-dimensional axial volume acquisition on meniscal lesions of the knee].

Axial three-dimensional volume scans obtained by magnetic resonance (MR) imaging were used to evaluate meniscal lesions of the knee in 28 knees of 26 cases. Axial 0.7 mm thin-sliced images with volume scan outlined the overall meniscal appearance for the first time. Axial volume scan was essential to the diagnosis of discoid lateral meniscus because only it could depict the characteristic elongated appearance of discoid lateral meniscus. Radial meniscal tears were depicted only by this technique: conventional sagittal and coronal views could not detect this type of meniscal tear. Volume scan could detect the precise extent of lesions with horizontal meniscal tears and meniscal degeneration. These MR findings obtained by axial volume scans were confirmed by arthroscopy in all cases. We concluded that volume scans were extremely useful in the evaluation of meniscal lesions because they offered axial views that provided much information on menisci located horizontally in the knee.

Adolescent↗
PubMed1991

[MRI of discoid lateral meniscus].

We retrospectively reviewed the MR examinations of 10 patients (17 knees) with surgically documented discoid lateral meniscus of the knee joint. As MRI of the knee is being used more often, the criteria for diagnosis of this entity with MRI need to be established. We tried to define MRI criteria for the detection of discoid menisci by performing numerical measurements of MR images on a display screen. The transverse diameter of the midbody of a discoid lateral meniscus averaged 21.9 mm (normal control: 8.6 mm), and its proportion to the transverse width of the tibia averaged 29.4% (normal control: 12.0%). The measurable difference in height between the discoid and the medial meniscus was negligible. The number of sagittal sections on which the anterior and posterior horns connected varied from two to five in cases of discoid lateral meniscus, and from zero to two in normal controls. Among these parameters, the transverse diameter and its proportion of the transverse width of the tibia proved to be the most reliable. We concluded that a discoid meniscus is indicated if a transverse diameter of a lateral meniscus exceeds 15 mm (proportion to the tibia: 20%).

Adolescent↗
PubMed1991

[A three-dimensional gradient refocussed 3D volume imaging of discoid lateral meniscus].

An axial 3D volume scan with MRI was applied to the evaluation of discoid lateral meniscus of the knee. By 0.7 mm-thick thin-sliced and gapless images with volume scan, characteristically elongated appearance of discoid lateral meniscus was clearly depicted. These MR findings completely accorded with those on arthroscopy. Our conclusion is that an axial 3D volume scan was essential to the diagnosis of discoid lateral meniscus.

Adolescent↗
PubMed1991

Nerve root avulsion of birth palsy: comparison of myelography with CT myelography and somatosensory evoked potential.

Findings at myelography and computed tomographic (CT) myelography were reviewed in 21 patients (22 limbs) with birth palsy; nerve root shadows were the focus of this study. Myelography demonstrated 51 completely avulsed roots (78%) and 14 incompletely avulsed roots (22%). A traumatic meningocele was detected at 38 roots on myelograms and 51 roots on CT myelograms. Thirteen avulsed roots (eight completely and five incompletely avulsed roots) (20%) were not associated with a meningocele. In nine patients who underwent brachial plexus exploration, myelographic findings were compared with root somatosensory evoked potential (SEP). SEP was not induced at 22 of 25 completely avulsed roots and was induced at all seven incompletely avulsed roots. Myelography and SEP were consistent in 29 of 32 roots (91%). It is concluded that myelography is indispensable for preoperative evaluation of cervical nerve root avulsion of birth palsy, because CT myelography is not sensitive to nerve root avulsion without a traumatic meningocele, and SEP cannot enable one to discriminate incomplete avulsion from intact roots.

Brachial Plexus↗
PubMed1991

A frameless, armless navigational system for computer-assisted neurosurgery. Technical note.

A computer-assisted neurosurgical navigational system has been developed which displays intraoperative manipulation on the preoperative computerized tomography (CT) scans or magnetic resonance (MR) images. The system consists of a three-dimensional digitizer, a personal computer, and an image-processing unit. Utilizing recently developed magnetic field modulation technology, the three-dimensional digitizer determines the spatial position and orientation angles of the resin probe, triangle-shaped pointer, or suction tube with a small attached magnetic field sensor. Four fiducial markers on the scalp were used to translate the spatial data of the probe onto the preoperative CT scans or MR images of the patient. With this frameless, armless navigational system, CT or MR-imaging stereotaxy can be applied to conventional open neurosurgery without limiting the operative field or interfering with the surgical procedures.

Adult↗
PubMed1991

[Computer assisted neurosurgery: development of a frameless and armless navigation system (CNS navigator)].

We have developed a computer assisted neurosurgical navigation system, which displays the point of ongoing surgical manipulation on the CT or MR images. The system utilizes magnetic field modulation technology for the detection of the 3 dimensional position and orientation angles of the probe, a resin pointer or suction tube with a small magnetic field sensor. Four fiducial markers on the scalp were used to translate the spatial data of the probe onto the CT/MRI images. This frameless and armless navigator with a spatial accuracy of 4mm, introduces CT/MRI-stereotaxy to conventional open neurosurgery without limiting the operative field or interfering with surgical procedures.

Adult↗
PubMed1990

[Myelography for nerve root avulsion in birth palsy].

Myelography and CT myelography (CTM) were reviewed in 18 cases of birth palsy with clinically suspected avulsion injury. Root-somatosensory evoked potential (root-SEP) was also reviewed for myelographic evaluation of the nerve root avulsion in birth palsy. Root-SEP is not induced in case of avulsed nerve roots, but is induced in case of both normal and incompletely avulsed roots. Myelography demonstrated 58 abnormal nerve roots in 18 cases (19 limbs); 45 (78%) complete and 13 (22%) incomplete nerve root avulsions. Each of complete and incomplete avulsions was defined as total absence and partial presence of rootlets on myelography, respectively. Traumatic meningoceles were detected at 46 roots (79%) on myelography and/or CTM; 35 roots on myelography and 45 roots on CTM. CTM could not detect only a very small meningocele at one root. At 11 roots CTM was superior to myelography in delineating a meningocele because CTM is sensitive to a poorly enhanced meningocele. CTM, however, could not diagnose nerve root avulsions so accurately as myelography, since myelography detected 12 (7 completely and 5 incompletely) avulsed roots without meningocele, whereas CTM could not delineate the nerve roots clearly. Thus, myelography is indispensable to evaluate nerve root avulsions without meningocele. Root-SEP was examined in 9 patients who underwent brachial plexus exploration. SEP was negative at 22/25 roots with complete avulsion and was positive at 7/7 roots with myelographically incomplete avulsion, regardless of presence or absence of any traumatic meningocele.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1990

External carotid artery embolization of dural arteriovenous malformations involving the cavernous sinus. Outcome and role of venous thrombosis.

Nine patients with dural arteriovenous malformations (AVMs) in the region of the cavernous sinus were treated by means of external carotid artery (ECA) embolization using polyvinyl alcohol. All AVMs received vascular supply from both the ECA and the internal carotid artery. Seven cases were clinically cured after embolization, while 2 cases with cortical venous drainage and high flow through the shunt were not completely cured. Venous thrombosis was observed in 5 cases before and in 9 after embolization. In 6 cases the drainage pattern changed owing to venous thrombosis. Complete thrombosis of the cavernous sinus was found on a follow-up angiography in 2 cases. Formation of venous thrombosis and occlusion of feeding arteries are crucial factors for success of ECA embolization. Dural AVMs with cortical venous drainage and high flow cannot be relieved by ECA embolization alone owing to difficulty in obtaining thrombosis of the veins.

Adult↗
PubMed1989

[A case of tracheopathia osteoplastica].

A case of tracheopathia osteoplatica in a 43-year-old man, detected incidentally at the upper gastrointestinal examination was reported. The examination showed a long segment esophageal compression from a paraesophageal lesion. CT was effective to demonstrate the typical narrowing and wall thickening of the trachea, and to demonstrate that the esophageal compression was caused by the deformed trachea.

Adult↗
PubMed1989

[Evaluation of CT myelography and conventional myelography for avulsion injury of nerve root--18 cases of birth palsy].

CT myelography (CTM) and conventional myelography were reviewed in 18 cases of birth palsy with clinically suspected avulsion injury. A traumatic meningocele was detected in 45 roots by CTM, and in 35 roots by myelography. CTM misinterpreted only one root with a very small meningocele. CTM was superior to myelography in delineating a traumatic meningocele, because CTM is sensitive to a poorly enhanced meningocele. On the other hand, CTM missed 9 avulsed roots without a meningocele. By myelography, these 9 roots were diagnosed as 6 roots of complete avulsion injury and 3 roots of incomplete avulsion. Myelography is indispensable in evaluating nerve root avulsion.

Child↗
PubMed1989

[Current status of radiation therapy in the treatment of malignant glioma:].

The patients of malignant glioma mostly consisting of anaplastic astrocytoma (AA) and glioblastoma (GM) were surveyed at the Committee for Compiling the Manual of Radiotherapy in the Treatment of Brain Tumors, organized by Japanese Association for Radiotherapy Research. Total 286 patients were treated at ten institutes during the period from January 1985 through December 1987. Numbers of cases with AA and GM were 130 and 156, respectively. Concerning the treatment volume, the medium field (50-100 cm2) was applied to 127 patients (37.4%) and the whole brain to 25 one (7.4%). The total dose was given by the range from 56 Gy to 65 Gy in 158 patients (47.6%). One-year survival ratio of AA and GM were 60-75% and 40-65%, respectively. For obtaining the improvement of local control rate, it is considered that the beam focusing onto the target lesion and the sufficient removal of the tumor are necessary and essential.

Astrocytoma↗
PubMed1989

[Adverse reactions and intracranial contrast medium after myelography].

Correlation between adverse reactions and intracranial contrast media after myelography was studied. Myelography was carried out for 12 cases with metrizamide and 14 with iotrolan. In all patients, cranial CT scans were performed 18 approximately 22 hours after myelography. CT attenuation value of subarachnoid cistern was higher than the gray matter in 12 cases and lower in 14 cases. Six cases suffered from adverse reactions, but only 1 case belongs to the higher group. No correlation between adverse reactions and residual amount of contrast medium on CT was recognized.

Adult↗
PubMed1988

MR imaging of dural arteriovenous malformations with ocular signs.

Four patients with dural arteriovenous malformation (AVMs) draining into the cavernous sinus, who presented ophthalmic manifestations, were studied by magnetic resonance (MR) imaging. In all patients signal decrease in the involved cavernous sinus was demonstrated in coronal spin-echo (SE) imaging. It is attributable to rapid venous flow in the sinus, and this "high velocity signal loss" is a fairly pathognomonic finding in this condition. We stress the validity of MR imaging in the primary diagnosis of dural AVMs with ophthalmic symptoms.

Arteriovenous Malformations↗