Biomedical subjects

H Isoda

Publications and source records attributed to H Isoda.

At least 73 records · Page 4Linked to original sources

PubMedDate not supplied

Squamous cell carcinoma arising in a mature teratoma with metastasis to the urinary bladder.

We describe a patient with squamous cell carcinoma arising in a mature teratoma. Magnetic resonance (MR) images revealed a solid lobulated mass attached to the ovarian cyst containing a fat-fluid level. The solid component with extension into pelvic fat showed as hypointensity on T2-weighted MR images with good enhancement. A metastatic tumor to the urinary bladder was also demonstrated.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Multiple myeloma: short T2 on MR imaging.

We describe a rare case of multiple myeloma with marked hypointense areas on both T1- and T2-weighted images. Amyloid deposition and calcification were not found histologically. Hypointensity on T2-weighted images may be caused by distributed free radicals produced by significant macrophages.

Back Pain↗

PubMedDate not supplied

MR angiography of thoracic outlet syndrome.

Thoracic outlet syndrome is a disorder caused by neurovascular compression of the brachial nerve plexus and the subclavian artery or vein by bones and muscles. We report the MR angiographic findings of a patient with thoracic outlet syndrome.

Adult↗

PubMedDate not supplied

MRI of intracranial neurovascular compression.

Twelve patients with clinical indications of intracranial neurovascular compression (6, hemifacial spasm; 4, trigeminal neuralgia; 2, vertigo and tinnitus) were studied by MRI. Axial 1 mm thick slices were obtained in a 1.5 T unit using a three-dimensional (3D) fast low angle shot data set of 32 contiguous slices. The data were post-processed with multiplanar reconstruction algorithms to obtain oblique sagittal (along the long axis of a nerve) images or coronal images with a slice thickness of 0.8 mm. The MR angiographic images were also obtained from the same 3D data set with maximum intensity projection algorithms. The MR studies showed that 9 of 12 patients had neurovascular compression caused by one or two arteries. These findings were verified at surgery. In two of the remaining three patients, MRI failed to delineate the affected nerves compressed by a vein in one, and a previously applied prosthesis in the other. In the last patient no neurovascular compression was found by MRI or at surgery.

Aged↗

PubMedDate not supplied

MRI of postoperative maxillary cysts.

OBJECTIVE: The purpose of this study is to review the MR characteristics of postoperative maxillary cysts (POMC). MATERIALS AND METHODS: The MR findings in 24 patients with 38 surgically confirmed POMC were retrospectively reviewed. RESULTS: Of 32 cysts detected by MRI, 31 cysts (96.9%) were well demarcated. Nineteen cysts (59.4%) were smooth and the others (40.6%) were irregular. Thirty cysts (93.8%) had signal intensities ranging from that of muscle to that of subcutaneous fat on T1-weighted imaging. On T2-weighted imaging 16 homogeneous (50.0% and 5 inhomogeneous (15.6%) cysts showed signal intensities equal to or higher than subcutaneous fat. The peripheral rims of 11 ring-like cysts (34.4%) also showed signal intensities equal to or higher than subcutaneous fat on T2-weighted imaging. Nine patients (37.5%) had multiple cysts. Their characteristic high signal intensities or ring-like patterns on T2-weighted imaging and well-demarcated margins enabled them to be discriminated from other tumors of the maxillary sinus, such as carcinoma. CONCLUSION: MR imaging is useful for diagnosis of POMC.

Female↗

PubMedDate not supplied

Effects of meal intake on the flow velocity in the superior mesenteric artery: evaluation with 2D phase mapping MRI.

OBJECTIVE: Reliable results in MR flow measurements have been reported in humans. The current study was performed to evaluate the effects of a meal intake on the flow velocities in the superior mesenteric artery (SMA) and aorta by using 2D phase-mapping MRI. MATERIALS AND METHODS: A constant flow phantom generating 0-150 cm/s of flow velocities was constructed to evaluate the accuracy of MR flow measurements. Eleven healthy volunteers underwent serial MRI once before and three times after a mixed meal intake (700 kcal). RESULTS: Reliable MR flow measurements were validated in the constant flow phantom. In the healthy volunteers, the SMA and aorta had triphasic flow velocity waveforms in one cardiac cycle. Ingestion of a mixed meal increased flow velocities in the SMA. Peak velocities were observed at 20 min after the meal. The aortic flow velocities were unaffected by the meal. CONCLUSION: A 2D phase-mapping MR technique is feasible to evaluate the SMA and aortic flow velocities. Evaluation of the flow velocities in the SMA may contribute to understanding intestinal as well as hepatic conditions in humans.

Adult↗

PubMedDate not supplied

Torsion of the wandering spleen: CT and angiographic appearance.

OBJECTIVE: To seek CT and angiographic appearances that characterize torsion of the wandering spleen. MATERIALS AND METHODS: The CT and angiographic findings of two cases of preoperatively diagnosed torsion of the wandering spleen were reviewed, and the findings were closely compared with intraoperative and histopathological findings. RESULTS: Characteristic CT appearance seemed to be a whirled appearance formed at the medial side of the displaced spleen. The angiographic finding that was characteristic of the disease was a tapered and abruptly twisted distal splenic artery. CONCLUSION: These findings were useful in making the early and correct diagnosis of this rare but fulminant condition.

Adolescent↗

PubMedDate not supplied

Clinical evaluation of pulmonary 3D time-of-flight MRA with breath holding using contrast media.

OBJECTIVE: Our goal was to evaluate the clinical utility of pulmonary 3D TOF MRA using a contrast medium and breath holding. MATERIALS AND METHODS: To determine an optimal imaging time in a pilot study, 30 sequential axial images were obtained for each of 18 patients by using a turbo fast low angle shot sequence immediately after a bolus injection of 5 ml Gd-DTPA. MRA consisted of five sequential MR scans performed using a 3D fast imaging with steady-state precession sequence on 13 patients. The imaging start time after a bolus injection of 10 ml Gd-DTPA was determined from the results of the pilot study. We hoped that the acquisition of the center of k-space of the first MRA was matched to the period of maximum effect of the first pass bolus for the pulmonary arteries. RESULTS: In a pilot study on average, pulmonary artery signal intensities were relatively high from 10.4 to 20.7 s after the contrast medium injection. The MR angiograms obtained at the optimal time were superior to those that followed. All pulmonary trunks and the right and left main pulmonary arteries were accurately recognized. MRA had a sensitivity of 80.0%, a specificity of 95.0%, and an accuracy of 94.5% for the detection of segmental artery stenosis or occlusion. Abnormal vessels were visualized in both patients with pulmonary sequestration. CONCLUSION: Pulmonary 3D TOF MRA using breath holding and a contrast medium is useful in demonstrating proximal pulmonary vasculature and pulmonary sequestration.

Adult↗

PubMedDate not supplied

Case report. Antenatal diagnosis of chorioangioma of the placenta: MR features.

We report a case of chorioangioma of the placenta, in which MR findings were useful in establishing the antenatal diagnosis. Polyhydramnios and a placental tumor that was 5 cm in size were visualized. The tumor had relatively high signal intensities on proton density imaging and T2-weighted imaging and showed partially high intensity signal rims on T1-weighted imaging, especially when using a breath-holding technique. Magnetic resonance imaging has an important role in detection and diagnosis of these lesions, particularly the larger tumors, so that appropriate steps can be taken to deal with the complications that may accompany this tumor.

Adult↗

PubMedDate not supplied

Pseudodynamic imaging of the temporomandibular joint: SE versus GE sequences.

Pseudodynamic MR imaging of the temporomandibular joints (TMJs) has been used for the evaluation of the functional aspects of the TMJs. To evaluate the value of T1-weighted spin-echo (SE) and gradient-echo (GE) techniques, both techniques were performed in 9 asymptomatic (mean 25.7 years, 22-23 years), and 25 symptomatic (mean 44.9 years, 20-71 years) subjects with signs and symptoms of internal derangement or osteoarthrosis of the TMJs. The imaging time for the SE (180 ms/15 ms/110 degrees; repetition time/echo time/flip angle) and GE (fast low angle shot; FLASH, 90 ms/12 ms/40 degrees) sequences was 27 and 28 s, respectively. In asymptomatic and symptomatic subjects, the confidence of the identification of the meniscal position was better on SE than GE images (3.6 +/- 0.6 vs. 2.9 +/- 0.9, p < 0.01, 3.2 +/- 0.8 vs. 2.8 +/- 0.8, p < 0.05), respectively and the sizes of the menisci were bigger on SE than GE images. The delineation of the condylar cortex was better on GE than SE images. For pseudodynamic imaging display of the TMJs, the SE images might be better than GE images to provide the stable recognition of the menisci.

Adult↗

PubMedDate not supplied

MRI of dumbbell-shaped spinal tumors.

PURPOSE: The purpose of our study is to review the clinical features and MR findings in patients with dumbbell-shaped spinal tumors that affect the intervertebral foramen. METHOD: Two radiologists retrospectively evaluated a total of 19 tumors from the period 1989-1994 that exhibited dumbbell configuration. These included 11 benign tumors, including 9 neurogenic ones, and 8 malignant tumors. RESULTS: The time between onset of symptoms and admission was shorter in patients with malignant tumors (mean 3.9 months) than in patients with benign tumors (mean 41.1 months). There was a statistically significant difference (p < 0.05) in the short/long axis ratios (minimum tumor diameter divided by maximum tumor diameter) in the vertebral canal components between benign and malignant tumors. All malignant tumors in this study were extradural and paraspinal type (p < 0.05). Most benign tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05). Many neurogenic tumors had regular margins and enlarged intervertebral foramina, while most malignant ones had irregular margins (p < 0.05> Many neurogenic tumors had cystic lesions (77.8%) and a string-of-beads structure (44.4%). Those tumors that surrounded the thecal sac in the vertebral canal and whose adjacent vertebral bodies had abnormal signal intensities were infiltrating and malignant. CONCLUSION: There are many kinds of dumbbell-shaped spinal tumors other than neurogenic ones. MRI is useful in diagnosing dumbbell-shaped spinal tumors, especially those of neurogenic origin, and aids in distinguishing benign from malignant tumors.

Adolescent↗

PubMedDate not supplied

MRA of intracranial aneurysm models: a comparison of contrast-enhanced three-dimensional MRA with time-of-flight MRA.

PURPOSE: The purpose of our study was to compare contrast-enhanced 3D MR angiography (MRA) using ultrafast spoiled gradient-recalled acquisition in the steady state (SPGR) with 2D and 3D time-of-flight (TOF) MRA for visualization of intracranial lateral saccular aneurysm models. METHOD: We used lateral saccular aneurysm models with a height of 10 mm and neck sizes of 2.5 and 10 mm. Imaging was performed using a 1.5 T MR system with a head coil. Contrast-enhanced 3D MR angiograms were obtained using 3D ultrafast SPGR sequence with and without the MR Smartprep technique. Two-dimensional and 3D TOF MR angiograms were also obtained. RESULTS: Contrast-enhanced multiphase 3D MR angiograms taken every 5 s after injection of contrast medium proved superior to the other MRA techniques for delineating lateral saccular aneurysm models. Contrast-enhanced 3D MRA images taken with inadequate delay after MR Smartprep trigger showed poor visualization of the aneurysm model. CONCLUSION: Use of contrast-enhanced multiphase 3D MRA with ultrafast SPGR with shorter TR and TE resulted in clear images of the lateral saccular aneurysm model.

Contrast Media↗

PubMedDate not supplied

BOLD contrast on a 3 T magnet: detectability of the motor areas.

To predict the potential and the limitations of functional MRI (fMRI) with a very high field magnet, the detectability and reproducibility of activation were evaluated by comparing the activation induced by a sequential finger movement task at 1.5 T with that at 3 T. The detectability of the premotor area, supplementary motor area (SMA), and ipsilateral sensorimotor area (SM1) showed significant improvement at 3 T. On the other hand, the detectability of contralateral SM1 was not significantly different between 1.5 and 3 T. The degree of activation was proportional to task demand in the ipsilateral SM1 and SMA, whereas that in the contralateral SM1 and SMA was not. FMRI with a 3 T magnet has greater potential for detection of neuronal activation as a functional network. These observations indicated that task demand and static magnetic field strength should be considered in interpretation of fMRI data for clinical usage.

Adult↗

PubMedDate not supplied

Enhancement of thermoradiotherapy by glucose administration for superficial malignant tumours.

The effect of hyperglycemia on the thermoradiotherapy of superficial malignant tumours was investigated. Glucose administration alone (500 ml of 10% glucose by intravenous drip infusion) reduced the tumour blood flow, when measured by laser Doppler flowmetry, to 66.1% of the baseline level at 30 minutes after the beginning of glucose infusion. Forty patients received glucose in tandem during the hyperthermia and radiotherapy (group A), and 38 patients received thermoradiotherapy alone (group B). The mean Tave (the average temperature of all intratumoural sensors) in group A was 43.4 +/- 1.1 degrees C while that in group B was 42.5 +/- 1.2 degrees C, i.e., glucose administrations significantly increased the tumour temperature (p < 0.01). In group A, complete tumour response (CR) was observed in 12 patients (30.0%), partial response (PR) in 25 patients (62.5%) and no response (NR) in three patients (7.5%). In group B, seven (18.4%), 20 (52.7%) and 11 (28.9%) patients showed CR, PR and NR, respectively. The tumour response rates were significantly different between two treatment groups (p < 0.05). The frequency of side effects of hyperthermia in groups A and B were 22.5 and 21.1%, respectively. This study suggests that hyperglycemia enhances the effectiveness of thermoradiotherapy.

Adult↗

PubMedDate not supplied

Construction of a laser transmission photo-scanner: pre-clinical investigation (report 2).

A prototype high-speed laser transmission photo-scanner using a 1 mm He-Ne laser beam and corresponding detector was constructed. Signals obtained from the detector were digitalized and stored in floppy disks by a micro-computer and displayed as color-coded pictures on the CRT monitor. The data were analyzed and absorption in the tissue was shown in a histogram. Breast tissue was simulated using pork, ham, lard, and cheese in a pre-clinical investigation. Normal breasts of volunteers were also examined. When disks of varying sizes were inserted into ham and cheese of various thicknesses, it was found that disks closer to the beam's point of entrance produced the best images, while disks in the center and those closer to the exit were poorly detected. Disks close to the surface were better detected than central lesions. Laser transmission images of normal breasts of twelve volunteers were symmetrical but often nonhomogeneous because of the complexity of breast tissue.

Breast↗

PubMedDate not supplied

Adult intussusception with an appendiceal mucocele diagnosed by CT and ultrasonography.

Mucocele of the appendix is rare and mainly found incidentally at surgery or autopsy. Clinically, this tumor is known to cause pseudomyxoma peritonei or intussusception in adults. We present a case of adult intussusception with a leading mass of appendiceal mucocele. Computed tomography was useful in resolving the nature of the leading mass.

Aged↗

PubMedDate not supplied

Caroli's disease associated with polycystic kidney: its noninvasive diagnosis.

We present a case of Caroli's disease, a relatively uncommon congenital abnormality, together with CT, US, and scintigraphic findings. The patient had chronic renal failure, complicated by polycystic kidney. No hepatic fibrosis was observed. Intrahepatic biliary lithiasis and gallstones were detected, but the patient was asymptomatic. Because surgery on an abnormal biliary tract may increase the risk of cholangitis, and intravenous administration of contrast media could be invasive in patients with polycystic kidney, CT, US, and scintigraphy are considered to play an important role in diagnosis. Noninvasive diagnostic procedures in Caroli's disease are described in this report.

Aged↗

PubMedDate not supplied

Fundamental studies of breast tumor detection with narrow beam laser scanning (report 1).

Fundamental studies were performed in which halogen parallel lights and narrow beam He-Ne laser scanning were applied to the image diagnosis of breast lesions. The breast tissue was simulated by fresh milk as an opaque material. With halogen parallel lights, objects close to the light could not be detected, objects in the center were slightly detectable, and those close to the detector were visualized distinctly. Narrow beam scanning with He-Ne laser produced contrasting results: the closer the object was to the light, the better its detectability. However, as the diameter of the object decreased, detectability worsened. The results of the experiments indicated that small lesions in the opaque breast tissue may be detected by He-Ne laser with narrow beam scanning.

Breast Neoplasms↗