BACKGOUND: The accuracy of a disposable blood pressure transducer (DBPT) is determined by its physical properties: natural frequency (NF) and damping coefficient (DC). We planned this study to investigate whether the NF and DC of a DBPT are altered by attaching extended catheters and evaluated changes of these physical properties over time. METHODS: Fifteen DBPT sets were connected to a monitor and recorder set. These sets were divided into three groups; five sets had catheters of normal length (Group 1), five sets had 50 cm extended catheters (Group 2), and five sets had 100 cm extended catheters (Group 3). The NF and DC of each system were measured using the fast flush (FF) test. After the DBPT sets were installed, the FF test was performed for each group at five time intervals: 4, 24, 48, 72, and 96 hours. RESULTS: The NF of Groups 2 and 3 decreased and their DC increased compared to those of Group 1. Whereas the NF of Group 3 increased over time, those of Groups 1 and 2 did not. The DC of Groups 2 and 3 decreased over time, but remained unchanged over time for Group 1. When the FF test was done at intervals longer than 24 hours, it was found that the NF, but not the DC, increased for all groups. CONCLUSIONS: Attention should be paid to interpret blood pressure using DBPTs measured by extended catheters and using DBPTs for long periods of time without FFs.
Blood Pressure ; Catheters* ; Transducers ; Transducers, Pressure*

PURPOSE: To evaluate and compare the diagnostic accuracy of MRI and ultrasound(US) for estimation of invasion depth of gastric carcinoma by correlation with histopathologic findings in vitro and to find out the best MR pulse sequence for detection and accurate delineation of tumor. MATERIALS AND METHODS: Resected specimen of total or subtotal gastrectomy from 53 patients with gastric carcinoma were done of imaging studies of MRI and US. And US was examined by using high frequency linear transducer for tumor invasion depth by a radiologist. In each case, both imaging findings of MRI and US were evaluated independently for tumor detection and invasion depth by consensus of two radiologists and were compared the diagnostic accuracy between two imaging modalities according to the histopathologic findings. MR imaging with five MR pulse sequences, spin echo T1 and in- and out-ofphase gradient echo T1 weighted images, FSE and SSFSE T2 weighted images, were performed. Five MR pulse sequences were evaluated and compared on the point of detection and accurate distinction of tumor from surrounding normal tissue. RESULTS: In EGC, diagnostic accuracy of US(77%) was superior than that of MRI(59%) but no statistically significant difference was noted between two imaging modalities(p=0.096). In AGC, both imaging modalities of MRIand US showed relatively high diagnostic accuracy as 97% and 84% respectively. Diagnostic accuracy of MRI was statistically better than that of US at the significant level(p<0.001). The best MR pulse sequence among five in each specimen was FSE T2WI(75.5%, 40/53) in both EGC and AGC. In AGC, FSE T2WI showed excellent imaging quality by showing very high ratio (93.5%, 29/31) of accurate delineation of tumor. CONCLUSION: MRI and US show relatively high diagnostic accuracy in the evaluation of tumor invasion depth of resected specimen in AGC. The most excellent pulse sequence of MRI for the evaluation of tumor invasion depth is FSE T2WI on the point of detection and accurate delineation of tumor in both EGC and AGC.
Consensus ; Gastrectomy ; Humans ; Transducers

No abstract available.
Humans* ; Skin* ; Transducers*

PURPOSE: To evaluate whether the accuracy of invasion depth assessment in gastric carcinoma in vitro can be improved with high-resolution spatial compound sonographic imaging. MATERIALS AND METHODS: In sixteen fresh gastric specimens obtained from patients with preoperatively biopsyproven gastric carcinoma, normal and lesional areas were scanned using conventional and compound imaging technique with a 15-MHz linear transducer. Two radiologists independently compared the sharpness and the contrast of images obtained with two different modes and determined the layers invaded by cancer with consensus. The invasion depths by images were compared with histopathologic results. RESULTS: The sharpness and the contrast in normal and lesional areas were significantly higher in compound imaging (p<0.01) than those in conventional imaging and interobserver agreement was over moderate, with kvalue of 0.41 to 0.86. But the accuracy in invasion depth assessment was 68.8% (11/16) on conventional imaging and 75% (12/16) on compound imaging and not different significantly between two modes (p>0.05). CONCLUSION: High-resolution spatial compound sonographic imaging has improved image quality, compared with conventional imaging, but the accuracy of invasion depth assessment in gastric carcinoma was not significantly different.
Consensus ; Humans ; Transducers ; Ultrasonography*

PURPOSE: To determine the rate of congruence and to standardize assessment of US (ultrasound) phantom images with the use of an ATS-539 multipurpose phantom for US equipment currently utilized in Korea MATERIALS AND METHODS: US phantom images were scanned with a 3.0-5.0 MHz convex transducer and were digitized by use of an analogue-digital converter. Members of a committee with consent evaluated the US phantom images from 108 types of ultrasound equipment. The dead zone, vertical and horizontal measurement, axial/lateral resolution, focal zone, sensitivity, functional resolution and gray scale/dynamic range were evaluated. Congruence or incongruence of ultrasound equipment was determined based on the results of dead zone, axial/lateral resolution and gray scale/dynamic range measurements. Other factors were evaluated for the possibility as criteria with the use of the Mann-Whitney U test and receiver operator characteristic (ROC) curve analysis. RESULTS: The dead zone, axial/lateral resolution and gray scale/dynamic range were 91.7%, 94.4% and 76.9%, respectively, for suitable US equipment. Considering all three factors, 78 types of ultrasound equipment were passed. The congruence rate of focal zone and functional resolution were 62.4% and 69.3% of the US equipment, respectively. CONCLUSION: Of the US equipment, 72.2% of the equipment was acceptable based on the dead zone, axial/lateral resolution, and gray scale/dynamic range measurements as determined with the use of an ATS-539 phantom. Focal zone and 8 mm-functional resolution can be useful as a standard in the assessment of a US phantom image.
Korea ; Quality Control ; Transducers

PURPOSE: Resonance frequency analysis (RFA), a non-invasive technique for the clinical measurement of implant stability, was investigated. Peri-implant bony defect may contribute to implant failure. This in vitrostudy evaluated the resonance frequencies according to various bony defects and determined whether the directional bone defect can affect the value of frequency analysis. MATERIAL AND METHOD: Fifteen 3.75 mm in diameter and 10 mm in length, machined selftapping implant fixture were used. Twelve types of bone defects that have different horizontal and vertical dimensions were simulated. Embedded implants were attached to the dental surveyor. Then, the transducer was connected with the implant fixture and the ISQ value was measured at four different directions. Two-way analysis of variance and post hoc Scheffe test were performed at the 95% significance level. RESULTS: The control group showed the highest ISQ value and 5 thread-360 degrees group had the lowest one. As the vertical exposure of implants in each angle was increased, the ISQ value was decreased. Although the horizontal exposure in each thread was increased, the ISQ value was not significantly decreased. CONCLUSION: Although the simulated defect type was different from each other, the ISQ value was similar among groups.
Transducers ; Vertical Dimension

PURPOSE: The present study was aimed to evaluate the influence of implant contact ratio and stiffness of implant-surrounding materials on the resonance frequency analysis (RFA) values. MATERIALS AND METHODS: Seventy resin blocks that had the different amounts (100, 50, 30, 15%) of resin-implant contact (RIC) were fabricated. Ten silicone putty blocks with 100% silicone-implant contact were also made. The implants with O5.0 mm x 13.0 mm were placed on eighty specimen blocks. The RFA value was measured on the transducer that was connected to each implant by Osstell Mentor. Kruskal-Wallis and Scheffe's tests (alpha=.05) were done for statistical analysis. RESULTS: The control resin group with 100% RIC had the highest RFA value of 83.9, which was significantly different only from the resin group with 15% RIC among the resin groups. The silicone putty group with 100% contact had the lowest RFA value of 36.6 and showed statistically significant differences from the resin groups. CONCLUSION: Within the limitations of this in vitro study, there was no significant difference in the RFA values among the resin groups with different RIC's except when the RIC difference was more than 85%. A significant increase in the RFA value was observed related to the increase in stiffness of material around implant.
Humans ; Mentors ; Silicones ; Transducers

PURPOSE: A new method has been devised to determine contact pressures in prosthetic components. A real time analysis of the contact pressure distribution could help fine tuned implant positioning and ligament balancing during Total Knee Arthroplasty. MATERIALS AND METHODS: Posterior cruciate reserving type procedures were done with externally rotated femoral cut. Femorotibial contact pressure was measured in four compartments in both flexion and extension position. A LOAD CELL located beneath the tibial plate changes the contact pressure into electric signal and DP-41S transformed the electric sign into the pressure unit. Adjunctive fine-tuning operation was done to approximate the equilibrium among the four compartments of the tibial plate. RESULTS: Femorotibial contact pressure were distributed between 17.1 N (Newton) to 33.4 N (average 23.6 N). A peak contact pressure was exhibited in the anteromedial compartment in extended knee and in the posterolateral compartment in flexed knee. CONCLUSION: A LOAD CELL electronic transducer technique was introduced. This method was tried to get the balanced equilibrium of contact pressure between Femorotibial components during TKA.
Arthroplasty* ; Knee* ; Ligaments ; Transducers

Sonographic measurements often give considerable diagnostic significance. However, large discrepancy betweenthe real anatomic sizes and sonographic measurements could cause an incorrect diagnosis. Authors carried out aseries of experiment using a phantom and two scanners and the results are as follows: 1. There is a littledifference in errors between two scanners, and the mesurement does not almost always correspond to the realdistance. 2. The rates of errors of the measurements are almost fixed regardless of the positions of thereflcetors. 3. There is no relationship between the transducer MHZ and error rate. 4. As the error is derived from the scanner electronics it is necessary to calibrate the scanner periodically, and if not calibrated one shouldconsider the error rate of the scanner in the anatomical measurement.
Diagnosis ; Transducers ; Ultrasonography

Esophageal retrograde peristalsis is known to be absent normally. This rare finding, if it happens, usually suggests a possibility that proximal ends of the manometric catheter are connected to the pressure transducers in a reverse order. We report a case showing repeated retrograde peristalsis during an esophageal manometric examination due to an inadventently hooked catheter in the esophagus during insertion. We suggest that if a retrograde peristalsis is repeatedly observed during a manometric session, an erroneous recording due to a hooked catheter in the esophageal lumen should be considered as one possibility.
Catheters* ; Esophagus* ; Peristalsis* ; Transducers, Pressure