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Biomedical subjects

Yoshifumi Narumi

Publications and source records attributed to Yoshifumi Narumi.

10 recordsLinked to original sources
PubMed2006

Evaluation of renal arteries in living renal donors: comparison between MDCT angiography and gadolinium-enhanced 3D MR angiography.

PURPOSE: The purpose of this study was to clarify and compare the accuracy of contrast-enhanced computed tomography (CT) angiography using multidetector-row helical CT (MDCT angiography) and gadolinium-enhanced MR angiography using three-dimensional Fourier transformation gradient-echo sequence (3D MR angiography) for preoperative evaluation of renal arteries in living renal donors. MATERIALS AND METHODS: A total of 42 living renal donor candidates underwent both MDCT angiography and 3D MR angiography before digital subtraction angiography (DSA). Each MDCT angiogram and 3D MR angiogram was prospectively interpreted, and the findings were compared with the DSA results. RESULTS: MDCT angiography identified all of the 12 supernumerary arteries detected by DSA, whereas 3D MR angiography identified only 8. MDCT angiography identified all of the 19 proximal arterial branches detected by DSA, whereas 3D MR angiography identified only 16. CONCLUSION: A more accurate depiction of renal arteries in living renal donors can be achieved with MDCT angiography than with 3D MR angiography.

Adult↗
PubMed2006

Noninvasive method using multidetector CT for calculating the relative blood supply ratio of duplicated renal arteries in renal donors.

PURPOSE: The aim of this study was to evaluate the correlation between the renal artery cross-sectional area measured by multidetector computed tomography (MDCT) and the nephrogram area calculated by renal arteriography in potential living renal donors with duplicated renal arteries. MATERIALS AND METHODS: Medical records of 18 patients with duplicated renal arteries who underwent both MDCT angiography and renal arteriography between 2001 and 2003 were retrospectively reviewed. All 20 kidneys were evaluated. Renal artery cross-sectional areas were measured using the workstation to which the CT data were transferred; the nephrogram areas on the digitized angiographic images were calculated using public domain software. Bland-Altman analysis was performed to compare the cross-sectional area ratio of the accessory arteries to the main renal arteries, with the ratios obtained from the nephrogram areas calculated from the arteriograms. RESULTS: The mean cross-sectional areas of the accessory and main renal arteries were 6.78 and 20.9 mm2, respectively. The ratio of the nephrogram areas calculated from the arteriograms ranged from 0.094 to 0.809. Bland-Altman analysis showed no significant difference. CONCLUSION: It is possible to predict the supply volume of accessory renal arteries by measuring the cross-sectional area of the accessory and main renal arteries in potential living renal donors.

Adult↗
PubMed2004

Is half-dose contrast-enhanced three-dimensional MR angiography sufficient for the abdominal aorta and pelvis?

PURPOSE: To evaluate the usefulness of half-dose contrast-enhanced magnetic resonance (MR) angiography for depicting the abdominal aorta and its major branches. MATERIALS AND METHODS: A total of 72 consecutive patients were randomly assigned to one of four groups that underwent MR angiography after receiving different concentrations (original or diluted to 50%) and total amounts (single or half-dose) of gadolinium chelate injected at different rates (1 or 0.5 mL/second). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the abdominal aorta and of the common and external iliac arteries were calculated, and two blinded readers rated the respective image qualities. RESULTS: The SNR and CNR of the abdominal aorta and the common iliac artery in the 0.5 mL/second groups were statistically significantly lower than those in the 1 mL/second groups. The differences in overall image quality across the four groups were not statistically significant. CONCLUSION: Half-dose MR angiography using diluted contrast medium injected at a rate of 1 mL/second depicted the abdominal aorta and its branches as clearly as using a full single dose.

Analysis of Variance↗
PubMed2004

[PACS for multi-slice CT--seamless integration implementing 3D and 4D workstations].

A PACS system for data management in multi-slice CT examination was upgraded using interactive 3D and 4D workstations and network computing technology. We categorized the original PACS (CT-PACS) as follows: (1) a fault-tolerant system linked with the hospital information system (HIS) and radiology information system (RIS); (2) an interactive network system using a workstation with real-time 3D and 4D reconstruction; (3) a system for research and development of software for 3D image analysis on the CT-PACS system. Because of the use of cooperative diagnostic supporting tools, no major problems occurred in daily clinical practice or research and education. In conclusion, CT-PACS with real-time 3D and 4D workstations was found to be helpful to radiologists and researchers in reading and analyzing large volumetric data.

Computer Communication Networks↗
PubMed2002

Intrabody three-dimensional position sensor for an ultrasound endoscope.

To avoid or reduce the X-ray exposure in endoscopic examinations and therapy, as an alternative to the conventional two-dimensional X-ray fluoroscopy we are developing an intrabody navigation system that can directly measure and visualize the three-dimensional (3-D) position of the tip and the trace of an ultrasound endoscope. The proposed system can identify the 3-D location and direction of the endoscope probe inserted into the body to furnish endoscopic images. A marker transducer(s) placed on the surface of the body transmits ultrasound pulses, which are visualized as a marker synchronized to the scanning of the endoscope. The position (direction and distance of the marker transducer(s) outside the body relative to the scanning probe inside the body) of the marker is detected and measured in the scanned image of the ultrasound endoscope. Further, an optical localizer locates the marker transducer(s) with six degrees of freedom. Thus, the proposed method performs inside-body 3-D localization by utilizing the inherent image reconstruction function of the ultrasound endoscope, and is able to be used with currently available commercial ultrasound image scanners. The system may be envisaged as a kind of global positioning system for intrabody navigation.

Algorithms↗
PubMed2002

Multi-detector row helical CT angiography of hepatic vessels: depiction with dual-arterial phase acquisition during single breath hold.

PURPOSE: To determine by using multi-detector row computed tomography (CT), in a triphasic hepatic dynamic study, which included single breath-hold dual-arterial phase acquisition, the accuracy and frequency of visualization of the small hepatic arterial and portal venous anatomy with angiographic correlation. MATERIALS AND METHODS: In 62 patients, pre- and postcontrast triphasic helical CT were performed by using a multi-detector row CT scanner, with 2.5-mm detector row collimation, at a pitch of 6. The first and second arterial phases were performed during a single breath hold. One reader, blinded to the results of the angiography, reviewed the first arterial phase images on a cine display to assess hepatic arterial anatomy. Visualization of the portal vein and its branches was assessed by using second arterial and portal venous phase images. RESULTS: Major arterial trunks (celiac, hepatic, superior mesenteric, and left gastric) were depicted in all cases. Visualization of small arteries was as follows: right and left hepatic, 62 (100%) of 62; middle hepatic, 52 (87%) of 60; cystic, 47 (90%) of 52; right gastric, 50 (89%) of 56; and right and left inferior phrenic, 57 (92%) and 55 (89%) of 62, respectively. Subsegmental or more peripheral branches of the portal vein were depicted in 83% of cases during the second arterial phase and in 96% during the portal phase. There was no difference in degree of visualization in these two phases. CONCLUSION: Multi-detector row CT angiography was able to depict the hepatic vascular anatomy.

Adult↗
PubMed2002

Evaluation of video capture equipment for secondary image acquisition in the PACS.

There are many cases in which picture archiving and communication systems (PACS) are built with old-type existing modalities with no DICOM output. One of the methods for interfacing them to the PACS is to implement video capture (/ frame grabber) equipment. This equipment takes analog video signal output from medical imaging modalities, and amplitude of the video signal is A/D converted and supplied to the PACS. In this report, we measured and evaluated the accuracy at which this video capture equipment could capture the image. From the physical evaluation, we found the pixel values of an original image and its captured image were almost equal in gray level from 20%-90%. The change in the pixel values of a captured image was +/-3 on average. The change of gray level concentration was acceptable and had an average standard deviation of around 0.63. As for resolution, the degradation was observed at the highest physical level. In a subjective evaluation, the evaluation value of the CT image had a grade of 2.81 on the average (the same quality for a reference image was set to a grade of 3.0). Abnormalities in heads, chests, and abdomens were judged not to influence diagnostic accuracy. Some small differences were seen when comparing captured and reference images, but they are recognized as having no influence on the diagnoses.

Humans↗
PubMedDate not supplied

Detection of hypervascular hepatocellular carcinoma by dynamic magnetic resonance imaging with double-echo chemical shift in-phase and opposed-phase gradient echo technique: comparison with dynamic helical computed tomography imaging with double arterial phase.

PURPOSE: The technique of double-echo chemical shift gradient echo magnetic resonance imaging (MRI) with the fast low-angle shot (double-echo FLASH) sequence provides in-phase and opposed-phase images in a single breath hold. The purpose of this study was to evaluate the efficacy of dynamic MRI with double-echo FLASH imaging for the detection of hypervascular hepatocellular carcinoma by comparing it with dynamic helical computed tomography (CT) imaging with double arterial phase. MATERIALS AND METHODS: Twenty-nine patients with 67 hypervascular hepatocellular carcinoma nodules who underwent both dynamic MRI with double-echo FLASH imaging (repetition time/echo time/flip angle: 160/3.6, 7.0/80 degrees ) and dynamic helical CT imaging with double arterial phase were enrolled in the study. For dynamic MRI, precontrast, arterial, portal venous, and equilibrium phase images were obtained before and approximately 19, 60, and 120 seconds, respectively, after intravenous injection of 0.1 mmol/kg of gadopentetate dimeglumine at a rate of 2 ml/s. For dynamic CT imaging, quadraphase images, including early arterial, late arterial, portal venous, and equilibrium phases, were obtained serially approximately 20, 30, 70, and 180 seconds, respectively, after intravenous administration of 2 ml/kg of 300 mgI/ml of nonionic contrast medium at a rate of 5 ml/s. Three masked observers independently interpreted images obtained with each technique in random order, separately and without patient identifiers. Sensitivity and positive predictive values as well as the area below the alternative-free response receiver operating characteristic curve (Az) for each imaging technique were calculated and compared statistically. RESULTS: Mean sensitivity and positive predictive values of MRI for hypervascular hepatocellular carcinoma were 48% and 94%, respectively, and those of CT imaging were 47% and 91%, respectively. In 11 (38%) of the 29 patients, at least one observer judged dynamic MRI to be superior, whereas in 5 patients (17%), dynamic CT was judged to be superior. There was no significant difference in the sensitivity and positive predictive values between these techniques (p > 0.05). There was no significant difference either in mean Az values between CT (0.55) and MRI (0.57) (p = 0.61). CONCLUSION: Dynamic MRI with double-echo FLASH imaging can detect hypervascular hepatocellular carcinoma as well as dynamic helical CT imaging with double arterial phase.

Adult↗
PubMedDate not supplied

Operating data and unsolved problems of the DICOM modality worklist: an indispensable tool in an electronic archiving environment.

PURPOSE: We evaluated the efficacy of DICOM worklist software for radiological modalities from the viewpoint of risk management, to reduce mislabeled image data in an electronic archiving environment. We focused on the following five points: 1) the effectiveness of the DICOM modality worklist, 2) problems involving incorrect patient and image data, 3) the presence of incorrect profiles despite the transfer of patient profiles online via the DICOM worklist, 4) ways to eliminate entry failure, and 5) further examination even if data entry were correct. MATERIALS AND METHODS: Retrospective data of patient profiles with image data were evaluated both before and after installation of DICOM modality worklist management software at Sakai Municipal Hospital. All radiology modalities were connected to RIS terminals in which DICOM modality worklist software was installed. Patient profiles were transferred online from RIS terminals to the modalities. It was not necessary for technologists to type patient profiles in usual examinations. RESULTS: Before installing the DICOM modality worklist software, the number of data entry errors was 31 and the rate was 6.4% of 487 examinations. After installation, manual data entry occurred in 80 of 1,994 examinations. The number of data entry errors for patient profiles was two, and the rate was 0.1% of the total examinations (p < 0.0001). Before installing the DICOM modality worklist, two wrong patient IDs that corresponded to other existing patient IDs were typed into the modality. No patient IDs were mixed up after installation of the DICOM modality worklist (p = 0.0385). CONCLUSION: The DICOM worklist was indispensable to electronic archiving because it decreased incorrect patient profiles that corresponded to image data loss. This was effective in decreasing patient mix-ups that could lead to serious malpractice. Despite the DICOM worklist, however, some incorrect patient profiles remained as a result of manual typing errors. The reasons for manual typing included emergency examinations, paper-based operations, and system shutdown. Furthermore, the risk of patient mix-ups remained even if the patient profile was correct. To eliminate or decrease medical accidents, determining why accidents happen and ensuring better data confirmation are necessary.

Archives↗