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Biomedical subjects

I Anno

Publications and source records attributed to I Anno.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Secondary signs of anterior cruciate ligament tear at MR imaging].

The value of secondary signs of anterior cruciate ligament (ACL) tear was evaluated MR images of 47 knees, 15 with normal, 6 with acutely torn and 26 with chronically torn ACLs confirmed at arthroscopy, were reviewed. Lateral and medial anterior tibial translocations (ATT), posterior cruciate ligament (PCL) bowing ratio and depth of lateral femoral notch (LFN) were measured. The degrees of lateral and medial ATTs and the PCL bowing ratio of the chronically torn ACLs were significantly higher than those of normal ACLs. With cutoff values of 5-mm lateral ATT, 2.5-mm medial ATT and 0.35-PCL bowing ratio, torn ligaments were distinguished from intact ligaments with accuracies of over 80%. Depth of LFN was less sensitive and less accurate. All knees with lateral ATT of 6.4 mm, medial ATT of 3.5 mm, PCL bowing ratio of 0.43 and LFN depth of 1.5 mm or more had torn ACLs. Higher correlations were revealed between lateral ATT and medial ATT, and also between lateral ATT and PCL bowing ratio. Combined criteria of lateral ATT and PCL bowing ratio indicated the highest diagnostic value as a reliable secondary sign of torn ACLs.

Adolescent↗
PubMed1995

[MR imaging features of chronically torn anterior cruciate ligament].

Magnetic resonance (MR) images of 40 knee joints with arthroscopically proved chronic anterior cruciate ligament (ACL) tears were retrospectively evaluated. MRI demonstrated various features of chronic ACL tears: 19 knees revealed with no identifiable ligamentous structure, and 21 had residual ligamentous structures. These pseudoligaments, 14 discontinuous bands and seven continuous bands with elongation, were residual torn ligamentous fibers and/or synovial tissues. All the discontinuous bands were disrupted from the femoral attachment and were likely to traverse the lower intercondylar space. Six disrupted ligaments were attached to the lateral aspect of the posterior cruciate ligament (PCL). Coronal T2-weighted gradient echo images showed better delineation of the disrupted femoral attachment and adhesion to the PCL. A chronic ACL tear with minimal elongation or with PCL attachment at a higher position may occasionally be difficult to distinguish from an intact ligament.

Adolescent↗
PubMed1995

Magnetization transfer contrast on gradient echo MR imaging of the temporomandibular joint.

Thirty-nine temporomandibular joints (TMJ) from 20 patients with suspected internal derangements were imaged by a 1.5 T MR imager. The on-resonance binomial magnetization transfer contrast (MTC) pulse was applied to gradient echo images with a dual receiver coil (9 s/section). With the use of an opening device, a series of sequential images were obtained at increments of mouth opening and closing. The tissue signal intensities with (Ms) and without (Mo) MTC were measured and subjective image analysis was performed. Compared with the standard images, MTC technique provided selective signal suppression of disks. The average of Ms/Mo ratio of the disks (0.56) was lower than that of the retrodiskal pad (0.79) and of the effusion (0.89). With MTC technique, fluid conspicuity was superior to standard image. However, no significant superiority was found in disk definition subjectivity.

Adolescent↗
PubMed1994

Changes in magnetic resonance images in human skeletal muscle after eccentric exercise.

To investigate the time-course of changes in transverse relaxation time (T2) and cross-sectional area (CSA) of the quadriceps muscle after a single session of eccentric exercise, magnetic resonance imaging was performed on six healthy male volunteers before and at 0, 7, 15, 20, 30 and 60 min and 12, 24, 36, 48, 72 and 168 h after exercise. Although there was almost no muscle soreness immediately after exercise, it started to increase 1 day after, peaking 1-2 days after the exercise (P < 0.01). Immediately after exercise, T2 increased significantly in the rectus femoris, vastus lateralis and intermedius muscles (P < 0.05) and decreased quickly continuing until 60 min after exercise. At and after the 12th h, a significant increase was perceived again in the T2 values of the vastus lateralis and intermedius muscles (P < 0.01) [maximum 9.3 (SEM 2.8)% and 10.9 (SEM 2.2)%, respectively]. The maximal values were exhibited at 24-36 h after exercise. In contrast, the rectus femoris muscle showed no delayed-stage increase. Also, in CSA, an increase after 12 h was observed in addition to the one immediately after exercise in the vastus lateralis, intermedius and medialis and quadriceps muscles as a whole (P < 0.01), reaching the maximal values at 12-24 h after exercise. The plasma creatine kinase activity remained unchanged up to 24 h after and then increased significantly 48 h after exercise (P < 0.05). Beginning 12 h after exercise, the subjects whose T2 and CSA increased less than the others displayed a faster decrease in muscle soreness.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Acute change of exercised muscle using magnetization transfer contrast MR imaging.

We evaluated the acute changes in exercised muscle using magnetization transfer contrast (MTC) MR imaging with a short repetition time sequence. Ten volunteers performed supine ankle dorsiflexion exercise. MTC gradient-recalled echo (GRE) images were obtained before and after exercise at 1.5 T. The effect of MTC was assessed by dividing the signal intensity on MTC GRE images by that on conventional GRE images (M(s)/M0). The signal intensity, M(s)/M0 and cross-sectional area of exercised muscle were all greater at 1-2 min after exercise than immediately after exercise. We propose that this additional increase in these parameters after exercise was due to physiological reflow or hyperemia. Since the M(s)/M0 showed a good correlation with free water content in exercised muscle, this ratio may provide a quantitative variable for evaluating dynamic change of water-macromolecule interaction in skeletal muscle.

Adipose Tissue↗
PubMed1993

[Magnetization transfer contrast imaging of the skeletal muscle in gradient recalled echo sequence].

The human midcalf muscle images were obtained using gradient recalled echo (GRE) sequence with and without magnetization transfer contrast (MTC) sequence. A significant decrease of relative signal intensity was observed in muscle with off-resonance irradiation. The percentage increase of signal intensity after dorsiflexion exercises was 55.6% and 29.0% for MTC-GRE and GRE sequence, respectively. MTC technique might be useful in improving contrast between many tissues as well as muscles.

Adult↗
PubMed1993

Demonstration of the deposition of hemosiderin in the kidneys of patients with paroxysmal nocturnal hemoglobinuria by magnetic resonance imaging.

Hemosiderinuria caused by intravascular hemolysis is a characteristic clinical feature of an acquired hemolytic disorder, paroxysmal nocturnal hemoglobinuria (PNH). We examined the deposition of hemosiderin (iron) in the kidneys of 6 patients with PNH using magnetic resonance imaging (MRI). Three patients with autoimmune hemolytic anemia (AIHA), a hemolytic disorder showing extravascular hemolysis, served as controls. In five of the six patients with PNH, a characteristic T2-weighted MRI of the kidneys, suggesting the deposition of iron (hemosiderin) predominantly in the renal cortex, was obtained. Hemosiderin-deposition was not revealed in the kidneys of any of the patients with AIHA. We conclude that MRI is a sensitive means of detecting hemosiderin deposited in the renal cortex of patients with PNH and that this feature is considerably specific for diseases showing intravascular hemolysis, as represented by PNH.

Aged↗
PubMed1992

Rapid T1 estimation using tagged magnetization-prepared gradient-echo MR imaging.

A technique for estimation of the longitudinal relaxation time of a large homogeneous object with an acquisition time of 4 s or less was developed by combining spatially selective rf tagging pulses with a T1-weighted magnetization-prepared gradient-echo sequence. Multiple 5-mm-wide tagged areas are laid orthogonal to the imaging section of interest. The contrast between each tag and the untagged regions differs because each tag is produced at a different time. The T1 value is determined from the nulling time at which tagged and untagged areas have no contrast.

Adipose Tissue↗
PubMed1991

Tears of cruciate ligaments and menisci: evaluation with cine MR imaging.

A cine magnetic resonance (MR) imaging technique, involving the acquisition of kinematic sagittal images during knee movement, was used to evaluate 52 symptomatic knee joints. Results were compared with those obtained by means of static three-dimensional (3D) MR imaging. Twenty-seven of the 28 anterior cruciate ligament (ACL) tears and 22 of 24 normal ligaments were correctly identified at cine MR imaging for a sensitivity of 96% and a specificity of 92%. Static 3D MR imaging yielded a sensitivity of 71% and a specificity of 88%. All four posterior cruciate ligament tears were identified at cine and 3D MR imaging. For meniscal tears, cine MR imaging yielded a sensitivity of 48% and a specificity of 96%; the sensitivity and specificity for 3D MR imaging were 71% and 96%, respectively. Cine MR imaging proved to be more useful than static MR imaging in assessing the tightness of cruciate ligaments, especially of those that were partially torn, and in assessing the movement of meniscal-free fragments. The increased information obtained with cine MR imaging may warrant continued investigation and clinical application.

Adult↗
PubMed1990

Effect of strength training on the relationship between magnetic resonance relaxation time and muscle fibre composition.

The effect of muscle hypertrophy on the relationship between magnetic resonance (MR) relaxation time and muscle fibre composition was investigated. Relaxation time and muscle fibre composition were measured in five subjects before and after a 20-week period of strength training. Muscle fibre composition in all subjects exhibited a significant shift to a predominance of fast-twitch (FT) fibres as a result of 20-week strength training (% area FT fibres: mean values from 49.8%, SD 17.9% to 57%, SD 5.6%; P less than 0.05). Longitudinal relaxation time (T1) and transverse relaxation time (T2) were prolonged significantly after strength training (T1 mean values from 334.9 ms, SD 13.6 to 359.0 ms, SD 9.0, P less than 0.001; T2 from 27.5 ms, SD 0.9 to 30.8 ms, SD 2.3, P less than 0.05). A constant relationship was observed in changes caused by strength training in muscle fibre composition (% area FT) and relaxation time, with a high correlation obtained between both parameters. These results indicate that MR relaxation time can be used for non-invasive estimation of muscle fibre composition.

Adult↗
PubMed1990

Mitochondrial encephalomyopathy (MELAS) with mental disorder. CT, MRI and SPECT findings.

A case of mitochondrial encephalomyopathy (MELAS) with mental disorder is reported. The SPECT study using 123I-iodoamphetamine (IMP) and MRI study revealed abnormality in the left parieto-occipital areas without abnormality in the brain CT or brain scintigram. These findings suggest a localized dysfunction of the brain capillary endothelium in association with the cerebral involvement of mitochondrial encephalomyopathy.

Acidosis, Lactic↗
PubMed1990

Moving knee joint: technique for kinematic MR imaging.

A system for magnetic resonance imaging of the knee joint during movement was developed by using a gating system and cine acquisition. The technique was used in 10 subjects: five with no history of knee pain or injury and five with tears of the anterior cruciate ligament. The normal ligaments and menisci appeared as low-intensity structures against intermediate-intensity hyaline cartilage. The ligament tears appeared discontinuous and faint against the background of the to-and-fro moving joint fluid.

Adult↗
PubMed1990

New trend of cardiac imaging--intravenous coronary arteriography by synchrotron radiation.

Synchrotron radiation is a broadspectrum intense X-ray beam. Selected X-ray wavelength was obtained by Bragg reflex. That is a monochromatic beam, which has a high spatial resolution, and has a K-edge discontinuity in attenuation coefficient, which, by energy subtraction, contributes to improve time resolution. An attempt to apply this method to intravenous coronary arteriography was performed in 7 anesthetized dogs. The beam was obtained by synchrotron radiation from accumulation ring, was reflected by silicon crystal, and was detected by 7 inch image intensifier system. Two-dimensional real time images were recorded on video tape. Phantom experiment was also performed. In dogs, coronary arteries were clearly distinguished by synchrotron radiation, especially at real time by video system. Phantom experiment suggested that coronary arteries could be visualized even over the visualized left ventricle. In conclusion, synchrotron radiation using two-dimensional real time images is expected to be useful in intravenous coronary arteriography in man.

Animals↗
PubMed1990

[MR imaging of the arm].

Thirty arms of healthy adults were studied with MR imaging using surface coil. Fine structures of the arm, such as muscular bundles, small vessels and nerves were clearly demonstrated. Deep fascia dividing muscular bundles appeared as high intensity on T1-weighed image due to fat deposition beneath the fascia. Aponeurosis is also flat sheet of densely arranged collagen fibers. With rather thicker layer of collagen fibers than fascia, aponeurosis appeared as low intensity sheet that was frequently demonstrated on MR images of the extremities.

Adult↗
PubMed1989

A case of multiple arteriovenous malformations and diffuse venous abnormalities with facial port-wine stain.

A case of left facial port-wine stain with right hemiparesis is reported. Radiologically, two arteriovenous malformations (AVM) and diffuse venous abnormalities were observed in the left hemisphere. AVM were seen in the basal ganglia. One was fed by a perforating artery from the MCA and drained into the superior petrosal sinus, and the other was fed by a perforating artery from the basilar artery and drained through the vein of Rosenthal into an extremely dilated vein of Galen. Venous abnormalities were obstruction and a decrease in the superficial cortical veins, as well as the formation of collateral veins in both the cortex and white matter. This case resembles Sturge-Weber syndrome (SWS), but there were no signs of leptomeningeal angiomatosis or venous angioma. We have been unable to find any case reports on SWS with AVM or AVM with diffuse venous abnormalities. We discuss the differences between our case and SWS.

Basal Ganglia↗
PubMed1989

[MRI and ultrasonography of cavernous hemangioma of the liver].

The frequency of detection of hemangioma has increased with the improvements of ultrasonography. Sonography detected 24 lesions out of 30 (80%), and 28 lesions out of 30 (93%) by MRI. MRI is superior to ultrasonography in detection rate. In T2 weighted spin echo image, most of the hepatic hemangiomas show moderately or markedly higher intensity than the liver and mildly higher or the same intensity as that of the spleen. MRI will play an important role in determination of necessity of further invasive diagnostic methods such as angiography or biopsy.

Adult↗
PubMed1989

[Quantitative evaluations of left ventricular function obtained by electrocardiographically-gated magnetic resonance imaging].

Using electrocardiographically-gated magnetic resonance imaging, regional cardiac function was evaluated in 12 normal volunteers and in 10 cases of old myocardial infarction. The optimal short axis of the left ventricle was selected at the chordae tendineae level. The left ventricle was divided into 12 segments using a computer-aided system, and percentile shortening fraction (%SF) and percentile wall thickening (%WT) were calculated in each segment by the fixed coordinate method. In the normal volunteers, heterogeneity of both %FS and %WT was observed, ranging from 25 +/- 13% and 37 +/- 13%, respectively in the septal segment, to 49 +/- 13% and 60 +/- 21%, respectively in the posterior segment. In the cases of myocardial infarction, decreased %FS and %WT were detected at the affected regions. The abnormal regions revealed by %WT tended to be narrower than those revealed by %FS. Thus the MR technique at the optimal axis may be useful for quantitative evaluations of regional cardiac function.

Adult↗