Millimeter wave silicon micromachined waveguide probe as an aid for skin diagnosis--results of measurements on phantom material with varied water content.

BACKGROUND: More than 2 million cases of skin cancer are diagnosed annually in the United States, which makes it the most common form of cancer in that country. Early detection of cancer usually results in less extensive treatment and better outcome for the patient. Millimeter wave silicon micromachined waveguide probe is foreseen as an aid for skin diagnosis, which is currently based on visual inspection followed by biopsy, in cases where the macroscopical picture raises suspicion of malignancy. AIMS: Demonstration of the discrimination potential of tissues of different water content using a novel micromachined silicon waveguide probe. Secondarily, the silicon probe miniaturization till an inspection area of 600 × 200 µm2, representing a drastic reduction by 96.3% of the probing area, in comparison with a conventional WR-10 waveguide. The high planar resolution is required for histology and early-state skin-cancer detection. MATERIAL AND METHODS: To evaluate the probe three phantoms with different water contents, i.e. 50%, 75% and 95%, mimicking dielectric properties of human skin were characterized in the frequency range of 95-105 GHz. The complex permittivity values of the skin are obtained from the variation in frequency and amplitude of the reflection coefficient (S11), measured with a Vector Network Analyzer (VNA), by comparison with finite elements simulations of the measurement set-up, using the commercially available software, HFSS. The expected frequency variation is calculated with HFSS and is based on extrapolated complex permittivities, using one relaxation Debye model from permittivity measurements obtained using the Agilent probe. RESULTS: Millimeter wave reflection measurements were performed using the probe in the frequency range of 95-105 GHz with three phantoms materials and air. Intermediate measurement results are in good agreement with HFSS simulations, based on the extrapolated complex permittivity. The resonance frequency lowers, from the idle situation when it is probing air, respectively by 0.7, 1.2 and 4.26 GHz when a phantom material of 50%, 75% and 95% water content is measured. DISCUSSION: The results of the measurements in our laboratory set-up with three different phantoms indicate that the probe may be able to discriminate between normal and pathological skin tissue, improving the spatial resolution in histology and on skin measurements, due to the highly reduced area of probing. CONCLUSION: The probe has the potential to discriminate between normal and pathological skin tissue. Further, improved information, compared to the optical histological inspection can be obtained, i.e. the complex permittivity characterization is obtained with a high resolution, due to the highly reduced measurement area of the probe tip.

[Rotational deformities following pediatric femoral shaft fracture]. / Der Rotationsfehler nach kindlicher Oberschenkelschaftfraktur.

At the beginning of 1983 65 children who had been treated at our hospital for fractures of the femoral shaft could be followed-up both clinically and radiologically at an average of 29 months after the injury. The radiological examination was performed with special regard to the rotational deformity; the torsion was measured using Rippstein's method. Out of 65 patients, 19 patients showed a difference between the angles of antetorsion of more than 10 degrees (29.2%) which we considered to be "rotational malpositions" (8 patients with endorotational and 11 patients with exorotational deformities). 40% of all fractures localized in the proximal third of the femur were accompanied by a rotational deformity of more than 10 degrees as compared to the other side. Exactly 4 years later a second examination of antetorsion was made using the same methodical procedure. 18 out of the 19 patients with rotational malpositions and 2 patients with a difference between the AT-angles of exactly 10 degrees could be re-examined. The average correction in the overall population was 3.4 degrees (-10 degrees to +5 degrees). In 15 cases we found a decrease in the difference between the angles of antetorsion by 5.8 degrees on an average, 1 patient showed no change in the difference, and in 4 patients the difference had increased by 3 degrees on an average. In 7 of the 20 patients (35%) the difference between the angles of antetorsion was less than 10 degrees, whereas the rotational malposition persisted in 13 cases. The extent of correction was much larger in patients with exorotational deformities than in those with endorotational deformities. A very close relation could be seen between the age of the children and the extent of correction. Furthermore, rotational deformities caused by fractures of the proximal third of the femoral shaft showed significantly less tendency towards correction than fractures with a more distal location.

[Indications for the Bankart operation]. / Die Indikation zur Bankartschen Operation.

This is a clinical and radiological follow-up on 61 patients operated upon between 1973 and 1983 according to the Bankart technique. In 84 per cent of all cases primary dislocation had taken place before the age of thirty. On an average 11 recurrent dislocations occurred before the operative procedure was performed. The radiological follow-up comprised X-rays in a.p. position with internal rotation of 60 degrees, in tangent plane according to Hermodsson as well as in dorsal tangent plane. In the modified score of Caroit and Cyprien 34 operations had excellent, 25 good, 2 moderate and 2 poor results (recurrent postoperative dislocation and deep infection). Neglecting those cases with severe deformation of the glenoid one can state that the Bankart technique offers fair results in the treatment of recurrent dislocation of the shoulder.

Degree and frequency of rotational deformities after infant femoral fractures and their spontaneous correction.

Based on 124 radiographic follow up results of infant femoral fractures the degree and frequency of a rotational deformity in relation to the fracture site and the therapeutical method are demonstrated and the reasons for the differences are discussed. The varying results of the follow up study and a repeated examination 4-6 years later confirm the assumption that the infant skeleton is able to correct even posttraumatic rotational deformities of the femur. The shape of the proximal femoral portion reveals that the correction takes place within the femoral stem rather than by torsion in the area of the femoral neck.

[Bone scintigraphy with 99mTc-pyrophosphate: pharmokinetics of the substance and clinical experiences with the scintigraphy]. / Knochenszintigraphie mit 99mTc-Pyrophosphat: Pharmakokinetik der Substanz und klinische Erfahrungen bei der Szintigraphie

Kinetics and clinical studies of bone scintiscanning with 99mTc-pyrophosphate in 92 patients with certified diagnosis allowed the following conclusions: 1. After i.v. injection 99mTc-pyrophosphate is distributed in 3 compartments, from which it is cleared with biological half-lives of 32.7 minutes, 5.1 hours and 22.54 hours respectively. The relative size of these compartments is 1 : 3 : 6. After application of the substance, an initially high renal excretion with a consecutive exponential drop can be observed. The optimal period for scintigraphic studies seems therefore to be from 3-6 hrs, as at this time there is still an adequate activity in bone structures, while the low background activity yields a good contrast on scintiscans. 2. The clinical results of bone scintigraphy with 99mTc-pyrophosphate with 88.6% correct diagnoses can be considered as "very good". This feature can partly be attributed to an improved correlation of radiographic and scintigraphic images by the use of a specially designed, combined radiographic-photoscanning detector system. 3. Preliminary results concerning the quantitative uptake of 99mTc-pyrophosphate in fractures of the extremities suggest, that the quantitative analyses of the registered data can provide valuable prognostic information in traumatic, inflammatory and neoplastic bone lesions.