Biomedical subjects

T Ishiguchi

Publications and source records attributed to T Ishiguchi.

85 records · Page 5Linked to original sources

PubMedDate not supplied

Is lower-dose digital fluorography diagnostically adequate compared with higher-dose digital radiography for the diagnosis of fallopian tube stenosis?

PURPOSE: In an effort to reduce patient radiation dose during selective fallopian tube catheterization, the diagnostic adequacy of fluoroscopic images was compared with digital radiographic images in both a phantom study and a clinical study. METHODS: For the phantom study polyethylene tubes with inner diameters of 1.30, 0.95, 0.80, 0.57, and 0.45 mm were used. Randomly selected tubes with/without stenoses, recorded by digital radiographic and last-image hold fluoroscopic images, were presented to five blinded radiologists, and receiver-operating characteristic (ROC) analyses were performed. For the clinical study tubal visualization as well as detectability of stenoses and occlusions were analyzed in 14 women using a 2-way analysis of variance for nonrepeated measures. RESULTS: The phantom study showed no significant differences between the two imaging techniques for 0.57-mm-diameter and larger tubes; in contrast, fluoroscopic images provided significantly lower detectability of stenoses in 0.45-mm-diameter tubes (p < 0.05). The clinical study showed inferior tubal visualization and diagnostic performance for fluoroscopic images. CONCLUSIONS: Although fluoroscopic images have inferior diagnostic capability in detection of tubal stenoses and occlusions, these images may be adequate for documenting tubal patency with spill into the peritoneal cavity.

Adult↗

PubMedDate not supplied

Display method can affect interobserver agreement: comparison of 'zoom-and-pan' and 'browse-and-paste' for primary CT interpretation.

Eight radiologists interpreted body CT images of 30 cases using a viewing station (six 17-in. monitors, 1024x1280). Using two different display methods, 'zoom-and-pan' and 'browse-and-paste', the readers described the presence or absence of liver tumors using a five-point rating scale and temporal changes between the current and previous studies using a seven-point rating scale. There was no significant difference in kappa values for tumor detection between the two display modes. However, in describing temporal changes, the kappa value of the browse-and-paste was significantly lower than that of zoom-and-pan (p<0.01). Browse-and-paste may have the disadvantage of greater interobserver variation.

Data Display↗

PubMedDate not supplied

Image storing system for radiation therapy (radiation oncology information system: ROIS) as a branch of diagnostic PACS; implementation and evaluation.

We have implemented the new system that is called as ROIS for storing medical images of the patients underwent radiotherapy as a branch of medium-scale diagnostic PACS. It was estimated that, for about nine years, we can store all medical images of the patients who received radiation therapy under the on-line storage condition. Further, we can retrieve all medical images of the radiotherapy patients on ROIS faster than conventional film library or on the diagnostic PACS, even if the patient had been treated many years ago. Implementation of ROIS provided us a great help in our clinical work.

Computer Communication Networks↗

PubMedDate not supplied

Accuracy of plastic replica of aortic aneurysm using 3D-CT data for transluminal stent-grafting: experimental and clinical evaluation.

PURPOSE: To plan stent-grafting for aortic aneurysms with complicated morphology, we prepared life-sized aortic replicas by laser stereolithography using helical 3D--CT data. The accuracy of the replica was evaluated by measurement of vessel phantoms and clinical 3D--CT data. METHOD: An imaginary aortic wall was created from helical CT images of the aorta, and a hollow plastic replica was produced by laser stereolithography. The accuracy of the replica was evaluated in five abdominal aortic aneurysms by experimental phantom studies and measurements of the replicas. RESULTS: The mean difference in measurements between 3D--CT images and model vessels and between 3D--CT images and aortic replicas was 0.2 mm each. Therefore, the difference in measurements between real aortic aneurysms and the replicas was at most 0.4 mm. CONCLUSION: The accuracy of the replica is satisfactory, making it useful for preoperative evaluation and simulation for stent-grafting.

Aortic Aneurysm, Abdominal↗

PubMedDate not supplied

High-resolution MR images of inner ear internal anatomy using a local gradient coil at 1.5 Tesla: correlation with histological specimen.

PURPOSE: To obtain high-resolution MR images of the inner ear at 1.5 Tesla with a local gradient coil and to correlate these images with the histological specimen. MATERIALS AND METHODS: All studies were performed on a 1.5 Tesla MR unit with a local gradient coil (23 mT/m, slew rate of 107 mT/m/ms). The cranio-facial region of a cadaver was examined using 3D-fast spin echo (FSE) imaging with the voxel size of 0.27 mm x 0.27 mm x 0.5 mm in 9 h 37 min. Two normal volunteers were examined with the same system using 3D-FSE imaging with the voxel size of 0.20 mm x 0.26 mm x 1.0 mm in 57 min. These images were correlated with the cadaver images and histological specimens. RESULTS: On cadaver images, internal structures such as the macula utriculi, macula sacculi, crista ampullaris, lamina spiralis ossea, ligamentum spirale cochleae, modiolus, scala tympani, scala vestibuli, and cochlear aqueduct were visualized. On the images of both volunteers, the same structures were visualized as on the cadaver images. CONCLUSIONS: This study confirmed that high-resolution MR images obtained at 1.5 Tesla can visualize inner ear internal anatomy. Knowledge obtained in this study may be of significant value for the diagnosis of pathology in the area of the inner ear.

Aged↗

PubMedDate not supplied

Real-time interactive MR imaging system: sequence optimization, and basic and clinical evaluations.

A real-time interactive MR imaging system (real-time MRI) is an MR scanner which has a fast image updating cycle and the ability to freely change slice orientation, just like an ultrasound imaging system. Recently, such a system has been developed and installed on a clinical 1.5-Tesla system. The purpose of this study was to optimize the pulse sequences for clinical use and to evaluate the clinical usefulness and basic functionality of real-time MRI. For T1-weighted imaging, FLASH (fast low angle shot) can be selected, and up to 5 frames per second can be acquired depending on the matrix size. For T2-weighted imaging, true FISP (fast imaging with steady-state precession) can be selected, and up to 4 frames per second can be acquired. Maximum C/N between liver and spleen was obtained at a flip angle of 20 degrees on FLASH. Maximum C/N between cardiac cavity and wall was obtained at a flip angle of 60 degrees on true FISP. Localization of the right and left coronary arteries could be performed within 30 seconds in three volunteers. Although the present real-time MRI system has drawbacks such as low spatial resolution and relatively low contrast resolution, we expect real-time MRI to be one of the most important tools for future clinical MRI.

Adult↗

PubMedDate not supplied

Stent-graft placement for pseudoaneurysm of the aorta.

PURPOSE: To evaluate the use of endovascular stent-graft placement to repair pseudoaneurysm of the aorta. METHODS: Six patients were treated with stent-grafts for pseudoaneurysms located in the thoracic aorta (n=2), thoracoabdominal aorta (n=3), and abdominal aorta (n=1). Etiologies of the pseudoaneurysms included leakage from surgical graft, penetrating atherosclerotic ulcer, pneumonia, perforated esophageal ulcer, and mycotic aneurysm. All patients were clinically considered to be at high surgical risk. RESULTS: Stent-grafts were successfully placed in all patients. There was one death in the perioperative period due to massive hemoptysis before stent-grafting. Two patients died of persistent infection. One patient with persistent perigraft leak died of rupture. Two other patients needed no further therapy for pseudoaneurysm. CONCLUSION: Stent-graft placement for pseudoaneurysm of the aorta can play the role of a temporizing method prior to surgical repair in high-risk cases and be a therapeutic alternative in cases without infection or perigraft leakage.

Aneurysm, False↗

PubMedDate not supplied

Arachnoid granulations on high-resolution MR images and diffusion-weighted MR images: normal appearance and frequency.

Arachnoid granulations (AGs), protrusions into the cerebral venous sinus lumen, have been reported on cerebral venography, contrast enhanced CT, and conventional MR imaging. Although thin-sliced high-resolution MR images and diffusion-weighted images are frequently obtained, there have been no detailed reports concerning AGs on these images. In this study, the frequency and positional distribution of AGs in the transverse sinus was investigated on thin-sliced high-resolution MR images, and their appearance on diffusion-weighted MR images was evaluated. At least one AG was found in 107 of 151 subjects (70.9%). No statistically significant differences were noticed between males and females or between the right and left sides. No significant correlations between age and size or between age and the number of AGs were noted. On diffusion-weighted images, all AGs showed iso-intensity to normal brain tissue, which was higher than the reported signal intensity of arachnoid cyst and lower than that of epidermoids. In conclusion, AGs are normal structures that are frequently found in the cerebral venous sinuses on high-resolution MR images. Knowledge regarding their frequency and normal appearance would be helpful to avoid confusion between pathological processes and AGs. It is also important to know that AGs are frequently found even in the younger population.

Adolescent↗

PubMedDate not supplied

Aortoiliac stenooculusive disease and aneurysms: screening with non-contrast enhanced two-dimensional cardiac gated cine phase contrast MR angiography with multiple velocity encoded values and cardiac gated two-dimensional time-of-flight MR angiography.

PURPOSE: To evaluate the performance of two-dimensional cine phase contrast MRA with multi-velocity encoded values (multi-VENC cine PC) and ECG-gated two-dimensional time-of-flight MRA (ECG-2D-TOF) for the detection of stenoocclusive lesions and aneurysms in the aortoiliac area, when each method was used individually and when the two methods were used together. METHODS: Forty-one patients were included in this study. Multi-VENC cine PC and ECG-2D-TOF were obtained first, then contrast enhanced three-dimensional magnetic resonance angiography (CE-3D-MRA) was performed as the standard of reference. Two observers reviewed the images separately without knowledge of patients' symptoms or histories. Sensitivities and specificities were obtained separately for stenooclusive lesions and aneurysms by two reviewers. RESULTS: When the two methods were applied together, high sensitivities (93.0 by observer 1 and 91.9% by observer 2) and adequate specificities (87.6 and 82.3%) were obtained for stenoocclusive lesions. For aneurysms, moderate to high sensitivities (91.1 and 71.1%) and high specificities (98.8 and 99.4%) were obtained. CONCLUSION: These results suggest that the performance of two non-contrast enhanced MRA techniques may be valuable as a screening tool when the two methods are applied together.

Aged↗

PubMedDate not supplied

CT and MR imaging of pancreatic cancer.

Recent improvements in imaging techniques have made it possible to improve the diagnostic accuracy for detection, staging, and indicating surgical resectability of pancreatic cancer. The latest advance in the computed tomography technique, is the introduction of subsecond multislice helical scanning that improves z-axis resolution in the reformatted images and three-dimensional rendering with a large volume data. Magnetic resonance imaging provides versatile information including magnetic resonance cholangiopancreatography that allows noninvasive delineation of the pancreatic and biliary duct systems. The presence of pancreatic cancer may best be evaluated by dynamic computed tomography or dynamic magnetic resonance imaging with administration of intravenous contrast material. Both computed tomography and magnetic resonance imaging are valuable for the preoperative assessment of local invasion and vascular involvement. Multislice helical computed tomography is currently considered as the best single modality for the diagnosis of pancreatic cancer as it provides excellent image quality. When advanced magnetic resonance imaging equipment is used as a primary modality, in the future, it may have a possibility to replace other imaging modalities.

Adenocarcinoma↗

PubMedDate not supplied

Contrast-enhanced MR angiography of the carotid artery using 3D time-resolved imaging of contrast kinetics: comparison with real-time fluoroscopic triggered 3D-elliptical centric view ordering.

PURPOSE: To evaluate contrast-enhanced MR angiography using the 3D time-resolved imaging of contrast kinetics technique (3D-TRICKS) by direct comparison with the fluoroscopic triggered 3D-elliptical centric view ordering (3D-ELLIP) technique. METHODS: 3D-TRICKS and 3D-ELLIP were directly compared on a 1.5-Tesla MR unit using the same spatial resolution and matrix. In 3D-TRICKS, the central part of the k-space is updated more frequently than the peripheral part of the k-space, which is divided in the slice-encoding direction. The carotid arteries were imaged using 3D-TRICKS and 3D-ELLIP sequentially in 14 patients. Temporal resolution was 12 sec for 3D-ELLIP and 6 sec for 3D-TRICKS. The signal-to-noise ratio (S/N) of the common carotid artery was measured, and the quality of MIP images was then scored in terms of venous overlap and blurring of vessel contours. RESULTS: No significant difference in mean S/N was seen between the two methods. Significant venous overlap was not seen in any of the patients examined. Moderate blurring of vessel contours was noted on 3D-TRICKS in five patients and on 3D-ELLIP in four patients. Blurring in the slice-encoding direction was slightly more pronounced in 3D-TRICKS. However, qualitative analysis scores showed no significant differences. CONCLUSION: When the spatial resolution of the two methods was identical, the performance of 3D-TRICKS was found to be comparable in static visualization of the carotid arteries with 3D-ELLIP, although blurring in the slice-encoding direction was slightly more pronounced in 3D-TRICKS. 3D-TRICKS is a more robust technique than 3D-ELLIP, because 3D-ELLIP requires operator-dependent fluoroscopic triggering. Furthermore, 3D-TRICKS can achieve higher temporal resolution. For the spatial resolution employed in this study, 3D-TRICKS may be the method of choice.

Adult↗

PubMedDate not supplied

Ultrasonographic and thermographic evaluation of the lower limb after transfemoral catheterization.

Ten adults undergoing routine transfemoral catheterization were randomly selected for study. Ultrasonography and thermography were performed within 48 hours before and after the catheterization procedure. Sites proximal and distal to puncture were assessed. There were no angiographic procedural complications in any case. Distal to the puncture, Doppler evaluation revealed a decrease in peak systolic velocity (PSV) in six cases, with four showing a greater than 30% fall, while three of the four cases with an increase had a less than 10% rise in PSV. Findings at the proximal site showed no distinct pattern. Changes in the resistive index at both sites were minimal. There was a significant increase in turbulence distal to the site of puncture in six cases. B-mode revealed arterial wall thickening compromising the lumen in half the cases. Thermography was done in four cases, and there was a tendency for an increase in limb temperature after the catheterization procedure. In view of the above-mentioned findings seen in "normal, uncomplicated" procedures, a larger study appears warranted to assess the significance of these findings and to attempt a correlation of the above results with the angiographic procedure.

Adult↗

PubMedDate not supplied

Cerebrovascular occlusion by catheterization and embolization: clinical experience.

Intravascular occlusion by various catheterization techniques was used to treat 27 cases of carotid-cavernous fistula, giant intracavernous aneurysm, and cerebral or dural arteriovenous malformation. Several case reports are presented. The detachable balloon technique proved valuable in the treatment of traumatic carotid-cavernous fistula and giant aneurysm. Calibrated-leak balloon catheterization with fluid embolization was used to treat cerebral arteriovenous malformation. Selection of embolic material is discussed.

Adult↗