Measurements of the group delay and the group delay dispersion with resonance scanning interferometer.

We developed a method for group delay and group delay dispersion measurements, based on location of interference resonance peaks. Such resonance peaks can be observed in transmittance or in reflectance when two mirrors are placed parallel to each other and separated by a thin air spacer. By using a novel approach, based on simultaneous processing of the data acquired for different spacer distances we obtained reliable results with high resolution. Measurements were performed both in transmittance and reflectance layouts depending on the reflectivity of the mirror to be measured. The developed method allows dispersion measurements of ultraviolet mirrors and ultra-broadband mirrors spanning more than one optical octave to be performed.

Metal ion levels in large-diameter total hip and resurfacing hip arthroplasty--preliminary results of a prospective five year study after two years of follow-up.

BACKGROUND: Metal-on-metal hip resurfacing is an alternative to metal-on-metal total hip arthroplasty, especially for young and physically active patients. However, wear which might be detected by increased serum ion levels is a matter of concern. METHODS: The aims of this preliminary study were to determine the raise of metal ion levels at 2-years follow-up in a prospective setting and to evaluate differences between patients with either resurfacing or total hip arthroplasty. Furthermore we investigated if the inclination of the acetabular component and the arc of cover would influence these findings. Therefore, 36 patients were followed prospectively. RESULTS: The results showed increments for Co and Cr in both implant groups. Patients treated with large-diameter total hip arthroplasty showed fourfold and threefold, respectively, higher levels for Co and Cr compared to the resurfacing group (Co: p < 0,001 and Cr: p = 0,005). Nevertheless, we observed no significant correlation between serum ion levels, inclination and arc of cover. DISCUSSION: In order to clarify the biologic effects of ion dissemination and to identify risks concerning long-term toxicity of metals, the exposure should be monitored carefully. Therefore, long-term studies have to be done to determine adverse effects of Co and Cr following metal-on-metal hip replacement.

[Measurement precision of sonography to evaluate movable meniscal bearings]. / Die Messgenauigkeit der Sonographie zur Evaluierung beweglicher Meniskallager.

After resection of the ACL, the knee exhibits a paradoxical movement but the effect of this movement on function,wear, and implant survival in a meniscal bearing total knee replacement (TKR) is not known. Up to now, only radiological methods are described to measure the meniscal bearing's movement. We developed a method using ultrasound for analyzing MB motion. In an in vitro study we compared ultrasound of 5 MHz with 8 and 12 MHz, we studied the effect of malrotation on the projection of plain and digital radiographs, and compared ultrasound of 8 MHz with plain and digital radiographs. In all three methods the distance was measured between the anterior border of the tibial component and the anterior rim of the meniscal bearing. The accuracy and precision of 8 and 12 MHz were identical and statistically significantly more accurate than 5 MHz (p<0.01). Malrotation had a significant impact on the radiological projection. Neutral rotated radiographs and ultrasound of 8 MHz did not differ in accuracy and precision, but ultrasound was significantly more accurate than any radiograph with a malrotation of 1 degrees or more (p<0.001). We conclude that ultrasound of 8 MHz is an alternative to radiological methods for the measurement of meniscal bearings' motion.

[In vivo assessment of mobility of meniscal bearings with ultrasound]. / In-vivo-Evaluierung der Meniskallagerbeweglichkeit mittels Ultraschall.

Clinical scores and fluoroscopically guided standard X-rays are still the golden standard for evaluating the outcome of total knee arthroplasty, but up to now there was no way to evaluate the function of mobile inlays except with digital fluoroscopy. We describe a new method using a flat 8-MHz ultrasound for the in vivo measurement of meniscal bearings (MB) with an accuracy and precision of 0.7 mm and 0.4 mm, respectively. In 73 knees with LCS classic total knee replacement, all of the medial (100%) and 71 of the lateral (97%) MB could be analyzed. The MB moved unhindered with an average total shift of 4.5 mm (range: 0.2-12.1) on the medial and 4.2 mm (range: 0.8-13.2) on the lateral side. A significant correlation was found between the active range of motion (ROM) of the knee joint and the medial MB's shift ( p=0.004) but not for the lateral MB ( p=0.114). Three knees had to be revised due to aseptic loosening (2) or excessive PE wear (1). No single parameter of the ultrasound analysis could be detected to be predictive for the MB's failure. Conventional ultrasound allows the analysis of MB function at low cost with an accuracy better than 1 mm. This method is an alternative to radiological methods and suitable for studies with larger numbers of patients followed over longer periods.

Technetium-99m-sestamibi scintimammography for the detection of breast carcinoma: comparison between planar and SPECT imaging.

UNLABELLED: The purpose of our study was to compare the results of planar and SPECT scintimammography for the detection of breast carcinoma. In addition, our goal was to determine whether SPECT reconstructed with filtered backprojection (FBP) or with iterative algorithms (ISA) can improve the sensitivity and specificity of planar scintimammography (SMM). METHODS: One hundred thirteen patients with suspicious physical examinations and/or mammography underwent planar lateral and anterior breast imaging as well as SPECT imaging after injection of 99mTc-sestamibi. We used a blind evaluation, both separately and combined, for planar SMM, ISA-SPECT and FBP-SPECT. Scintigraphic findings were correlated with the final histopathological diagnoses. RESULTS: The sensitivity of planar SMM was 80% with a specificity of 83%. All ISA-SPECT studies were of diagnostic quality, while FBP-SPECT was considered nondiagnostic in 14 that were excluded for statistical calculation. Sensitivity of ISA-SPECT and FBP-SPECT were 71% and 69%, respectively. Specificity was 70% for ISA-SPECT and 66% for FBP-SPECT. Combined planar SMM plus ISA-SPECT sensitivity was 85% (81% for planar SMM plus FBP-SPECT) with a specificity of 72%. Three carcinomas indeterminate on planar SMM were correctly identified by combined planar SMM plus ISA-SPECT. ISA-SPECT and FBP-SPECT provided additional information to planar SMM with respect to localization of sestamibi uptake, tumor extent, improved diagnostic certainty and detection of axillary nodes in 40 and 14 patients, respectively. CONCLUSION: ISA reconstruction is the preferable approach to SPECT data. Combined with planar SMM, ISA-SPECT can improve sensitivity. SPECT is useful in cases of indeterminate and positive planar SMM.

Comparison of technetium-99m-sestamibi scintimammography with contrast-enhanced MRI for diagnosis of breast lesions.

UNLABELLED: Scintimammography using 99mTc-sestamibi and contrast-enhanced MRI were performed to determine the diagnostic accuracy of either method in the diagnostic workup of patients suspicious for breast tumors. METHODS: Fifty-six patients (42 with indeterminate mammograms) underwent preoperative prone planar scintimammography and pre- and postcontrast-enhanced MRI. Visually determined signal increase after application of Gd-DTPA was compared with visually scored sestamibi uptake, and the diagnoses of both methods were correlated with the final histopathologic results. RESULTS: Overall, sensitivity and specificity of scintimammography for diagnosing breast cancer were 88% and 83%, respectively. In the subgroup of patients with indeterminate mammograms, sensitivity was 79% and specificity was 83%. MRI readings provided a higher sensitivity (91% with respect to all patients and 89% with respect to patients with indeterminate mammograms), but a considerably lower specificity (52% in both groups) due to contrast-enhancement in different benign lesions. CONCLUSION: Due to its considerably higher specificity, scintimammography rather than MRI may be suitable to reduce the number of breast biopsies which yield benign results. Thus, this method may be suggested as the preferable tool in the diagnostic workup of patients with indeterminate mammographic findings.

Evaluation of mammographic breast lesions with Tc-99m sestamibi scintimammography and contrast enhanced MRI.

Scintimammography using Tc-99m sestamibi and contrast enhanced MRI were performed in order to determine the accuracy of both methods in the diagnostic work up of patients with suspicious or indeterminate preliminary diagnosis. 25 controls and 56 patients (14 with suspicious and 42 with indeterminate preliminary diagnoses), in whom physical examination and/or mammography warranted breast biopsy, underwent prone planar scintimammography. Sestamibi uptake was scored visually and measured using the ROI technique to enable semiquantitative evaluation. The patient group additionally underwent plain and contrast enhanced MRI. Visually determined signal increase following application of Gd-DTPA was compared with scintigraphic findings and final histopathologic results. Sensitivity and specificity of semiquantitative scintimammography for diagnosing breast cancer was 88% and 87%, respectively. Based on ROC analysis a target/non target ratio R > 1.3 was shown to be the optimal threshold for separating benign from suspicious scintigraphic diagnoses. MRI reading provided a slightly higher sensitivity (91%), but a considerable lower specificity (52%) due to contrast enhancement of different benign lesions. In the clinically important patient subpopulation with indeterminate results from previous diagnostic procedures, sensitivity of scintimammography fell to 79%, while specificity remained at 87%. MRI revealed a higher sensitivity of 89% and a lower specificity of 52%. Our data indicate that semiquantitative scintimammography using Tc-99m sestamibi provides a comparable sensitivity to contrast enhanced MRI in the assessment of breast cancer. The latter does not reduce the number of biopsies yielding benign results due to the high number of false positive diagnoses. Therefore, scintimammography seems to be the preferable tool in the diagnostic work-up of patients with indeterminate mammographic diagnoses.