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R Andresen

Publications and source records attributed to R Andresen.

At least 55 records · Page 3Linked to original sources
PubMed1997

Assessing the degree of osteoporosis in the axial skeleton using the dependence of the fractal dimension on the grey level threshold.

Combining the measurement of bone mineral density (BMD) and the classification of the trabecular structure in cancellous bone improves the estimation of the degree of osteoporosis. A fractal method for the automatic quantitative classification of the trabecular structure in midvertebral slices of lumbar vertebrae is introduced. This method is based on the computation of the fractal dimension (box counting method) for varying binarization thresholds. Radiographic images from 30 lumbar vertebrae and CT images from an additional 16 lumbar vertebrae were analysed by calculating the dimension D in dependency of the threshold value T. The function D(T) was normalized by the average image grey value, eliminating the bone mineral density from the computations. The results show that the images of the lumbar vertebrae have fractal properties, and the function D(T) has a typical behaviour that allows the discrimination of the degree of osteoporosis. With two parameters extracted from the function D(T) the correlation coefficients with BMD were both -79% for the radiographic images, and -93% and -91% for the CT data, respectively.

Bone Density↗
PubMed1997

Evaluation of the cortical structure in high resolution CT images of lumbar vertebrae by analysing low bone mineral density clusters and cortical profiles.

The structural classification of trabecular bone is of considerable clinical importance for the diagnosis of osteoporosis. Assessment of the cortical bone mineral density (BMD) and analysis of cortical structure is necessary because the cortex is also affected by osteoporosis. We describe a method for the automatic classification of the cortex from its structure on high resolution (HR) CT images. The method is based on the distribution of areas with low BMD in the cortex. Two different approaches are presented; one uses the grey scale profile of the cortical ridge, and the other one evaluates the distribution of connected regions (clusters) of low BMD. i.e. areas that lie below a certain threshold value. In HRCT images from 22 lumbar vertebrae, the number of intersections of the cortical intensity profile with a horizontal line was determined at various positions of this threshold line. At a certain position, there was a local maximum in the number of intersections which was 38% higher in the osteoporotic cases. The maximum shows a moderate correlation with the cortical BMD of rni = -0.72 (p < 0.0001). The number nc of connected regions (clusters) with pixel values below a certain threshold value was determined in relation to the threshold value T. The resulting function nc(T) shows a relative maximum slightly below the average grey scale value of the respective image. The curve depends on the degree of osteoporosis: the height of the maximum (i.e. the maximal number of clusters ncmax) allows distinction to be made between different degrees of osteoporosis, and ncmax shows a correlation with the cortical BMD of rnc = -0.84 (p < 0.0001).

Aged↗
PubMed1997

Local interferon-alpha 2b is not an effective treatment in early-stage Peyronie's disease.

OBJECTIVE: Peyronie's disease is characterized by an acquired penile deviation that may lead to severe penile deformity. It is refractory to most conservative therapy, and surgical correction is therefore the treatment of choice once the disease process has come to a halt. Basic science, as well as our first clinical results on the use of interferons (IFNs), have been promising, suggesting a beneficial effect in the early noncalcified disease stage. MATERIAL AND METHODS: From July 1994 to October 1995, 30 patients suffering from early Peyronie's disease were treated with three local injections of 3 million units of IFN-alpha 2b each into the plaque(s). The interval between the injections was 1 week. Patients were assessed clinically and ultrasonographically 6 months after the last injection. RESULTS: Peyronie's disease clinically improved in only 1 case, remained stable in 26 patients and worsened in 3. In 7 patients, a total of 10 plaques at different sites were detected. By ultrasonography the treated plaques now showed calcifications in 3 cases, remained unchanged in 26 and could not be detected in 1 case. Of the 10 new plaques, 2 showed calcifications. Side effects (myalgia, fever) were considerable; in 74 of 90 injections, fever > 38 degrees C occurred, and a total of 8 working days were lost. CONCLUSION: IFN-alpha 2b, given according to our regimen, is not useful for the treatment of Peyronie's disease in the early stage since the disease progress continues at different sites in about 25% of the patients, and the side effects are untolerable. Our results also demonstrate that local therapy is not indicated in Peyronie's disease.

Adult↗
PubMed1997

[Soft tissue emphysema as manifestation of perforating diverticulitis].

Pronounced soft-tissue emphysema expressing disseminated fecal abscess formation in perforated colonic diverticulitis is described. Cervical, mediastinal, and thoracic dissemination and involvement of the scrotal space and the thigh reveal the original retroperitoneal localization as well as the unusual but potential dissemination. The diagnostic methods are described.

Abdominal Abscess↗
PubMed1997

[Development of a CT data-based score for prediction of fracture risk in osteoporosis].

It should be examined how far BMD semiquantitative (profile analysis) and qualitative datas (architecture of spongy bone, age of patient) can be combined in one score in order to improve the assessment of fracture risk. SE-QCT was performed in 220 patients with a mean age of 55.8 (33-84) years from whom conventional X-ray images of the thoracic and lumbar spine were available. In the axial scans spongiosa architecture was classified and a density profile analysis was carried out. This was followed by gradation of BMD values, different types of spongiosa architecture, profile analysis and age of patient to a numerical score. This was compared to the number of fractures, whereby the patients were separated into three groups: group I = no fracture, group II = one fracture, group III = more than one fracture. The BMD values, types of spongiosa architecture, semiquantitative profile analysis can be significantly assigned to the groups I and II (p < 0.02), groups I and III (p < 0.001), and the groups II and III (p < 0.05). By combining BMD values, architecture of spongy bone, density profile analysis, and age of patients without fracture, scale 8-12 = patients with or without fracture, scale 13-16 = patients with at least one fracture [corrected].

Adult↗
PubMed1996

Enlargement of the third intercondylar tubercle of Parsons as a sign of osteoarthritis of the knee: a paleopathologic and radiographic study.

PURPOSE: To correlate presence and size of the third intercondylar tubercle of Parsons (TITP) with occurrence and severity of osteoarthritis of the knee. MATERIALS AND METHODS: In 100 paleopathologic tibial specimens and on 160 clinical knee radiographs, size of the TITP was correlated with osteoarthritis of medical and lateral femorotibial joints (FTJ) and with prominence of tibial spines. RESULTS: TITP size correlated significantly with osteoarthritis of the tibial plateau in the paleopathologic specimens (P<.0001). TITP size correlated significantly with osteoarthritis of medial FTJ and tibial spines on radiographs (P<.0001). Of 85 patients without osteoarthritis of the medial FTJ, 49 (58%) had no TITP, 33 (39%) had small TITPs, and three (4%) had medium or large TITPs. TITPs were found in 15 (88%) of 17 patients with pronounced osteoarthritis. CONCLUSION: Frequency and prominence of TITPs are increased in patients with osteoarthritis of the medial FTJ and prominent tibial spines. Prominent TITP is a secondary sign of osteoarthritis. At histologic examination, increasing size of TITPs represents osteophytosis or enthesopathy of the TITP.

Adolescent↗
PubMed1996

Imaging of osseous and cartilaginous intraarticular bodies in the knee: comparison of MR imaging and MR arthrography with CT and CT arthrography in cadavers.

PURPOSE: To compare magnetic resonance (MR) imaging and MR arthrography with computed tomography (CT) and CT arthrography in the detection of intraarticular bodies in the knee. MATERIALS AND METHODS: Cuboid (3- or 6-mm-long sides) osseous and cartilaginous bodies were implanted in 16 cadaveric knee specimens. MR imaging was performed with T1-weighted spin-echo (SE), T2-weighted SE, proton-density-weighted SE, gradient recalled acquisition in the steady state (GRASS), and spoiled GRASS sequences. MR arthrography was performed in two phases with saline and 2 mmol/L gadopentetate dimeglumine. CT and CT arthrography were performed in the transaxial plane. RESULTS: MR arthrography yielded the highest accuracy for the detection of osseous and cartilaginous bodies combined (92%) and was significantly (P < .01) better than MR imaging (57%-70%), CT arthrography (80%), and CT (74%). Accuracy of CT arthrography was significantly better than that of MR imaging and that of CT. Accuracy of saline-enhanced MR arthrography was significantly inferior (P < .001) to that of gadolinium-enhanced MR arthrography. CONCLUSION: MR arthrography is the best imaging technique for detection of individual intraarticular bodies. CT arthrography is the second most accurate method. Spoiled GRASS and T2-weighted SE sequences are the most accurate at MR imaging. The presence of intraarticular fluid and performance of saline-enhanced MR arthrography improve detectability of intraarticular bodies.

Arthrography↗
PubMed1996

MR diagnosis of retropatellar chondral lesions under compression. A comparison with histological findings.

PURPOSE: The aim of the study was to improve the chondromalacia patellae (CMP) diagnosis by MR imaging under defined compression of the retropatellar cartilage, using a specially designed knee compressor. The results were compared with histological findings to obtain an MR classification of CMP. METHOD: MR imaging was performed in in vitro studies of 25 knees from cadavers to investigate the effects of compression on the retropatellar articular cartilage. The results were verified by subsequent histological evaluation. RESULTS: There was a significant difference in cartilage thickness reduction and signal intensity behaviour under compression according to the stage of CMP. CONCLUSION: Based on the decrease in cartilage thickness, signal intensity behaviour under compression, and cartilage morphology, the studies permitted an MR classification of CMP into stages I-IV in line with the histological findings. Healthy cartilage was clearly distinguished, a finding which may optimize CMP diagnosis.

Adolescent↗
PubMed1996

Ultrasound and soft-tissue radiography to monitor local interferon-alpha 2B treatment in Peyronie's disease.

PURPOSE: We attempted to assess objectively the response of Peyronie's disease plaques to local interferon-alpha 2B. MATERIAL AND METHODS: Twenty patients were treated with 5 local injections of 1 million units of IFN-alpha 2B into a single designated plaque. Before treatment, and 4 weeks and 6 months after treatment, the plaques were examined ultrasonographically. Each time, a histogram profile was performed. All patients also underwent soft-tissue radiography in 2 planes using the mammography technique before and 6 months after treatment. RESULTS: We found that with ultrasonography the plaques could be classified into 3 groups depending on degree of calcification, from nil to complete. Radiography detected calcifications better than ultrasonography but failed to detect plaques without calcification. The degree of calcification was negatively correlated with the response to treatment, since noncalcified plaques responded best, while fully calcified plaques failed to respond. CONCLUSION: In Peyronie's disease, ultrasonography is an important tool for non-invasive monitoring treatment response and for preselecting patients for medical treatment.

Follow-Up Studies↗
PubMed1995

Evaluation of penile arteries with color-coded duplex sonography: prevalence and possible therapeutic implications of connections between dorsal and cavernous arteries in impotent men.

Penile revascularization for cases of arteriogenic impotence is based on the assumption of hemodynamically relevant connections between the dorsal penile and cavernous arteries. In 325 clinically impotent patients color-coded duplex sonography was performed with the penis flaccid and tumescent after intracavernous injection of 10 micrograms prostaglandin E1. We measured peak flow velocity, end diastolic flow velocity and resistance in the dorsal arteries, deep cavernous arteries and connections perforating the tunica albuginea between the 2 systems. Of our patients 14% had at least 1 such anastomosis with a peak flow velocity exceeding 25 cm. per second after stimulation. Peak flow velocities less than 20 cm. per second were noted only in arteriogenically impotent patients, while those exceeding 25 cm. per second without later rigid erection occurred only in patients with venous occlusive dysfunction and end diastolic flow velocity exceeded 5 cm. per second. We conclude that penile revascularization should be contemplated only if hemodynamically relevant connections are detected, peak flow velocity in the cavernous arteries is less than 20 cm. per second and end diastolic flow velocity is less than 5 cm. per second.

Alprostadil↗
PubMed1995

Treatment of Peyronie's disease with local interferon-alpha 2b.

Peyronie's disease is an illdefined condition that often leads to severe penile deformity. Various conservative treatments have failed to have any impact, and surgery remains the mainstay of therapy in advanced cases. Recent reports of successful treatment of related diseases, notably keloid formation, with interferons (INF) have prompted us to use this biologic response modifier to alter the behavior of the myofibroblast, the cell most likely responsible for the development of Peyronie's disease. From December 1992 to July 1994, 25 patients suffering from Peyronie's disease were treated with five local injections of 1 million units of INF-alpha 2b each into a single designated and ultrasonographically measured plaque. The interval between the injections was 1 week. The patients were assessed clinically and ultrasonographically 1 and 6 months after the last injection. The condition improved clinically in only 1 case, but progressed in none. The measured plaque size decreased in 7 no or mildly calcified cases, remained stable in 12 cases, and increased in 6 patients, (solely calcified plaques). Side effects (myalgia, fever) occurred in 4 patients; of these 2 patients withdrew from treatment. INF-alpha 2b given according to our regimen is at best usefull for the treatment of Peyronie's disease in the early, noncalcified stage during which it displays verifiable impact on the plaque treated and also helps alleviate the plaque-associated pain; but further dose-finding studies will have to be performed to identify clinically relevant treatment regimens.

Adult↗
PubMed1995

[Conventional arthrography in comparison with magnetic resonance tomography and arthroscopy in internal knee joint injuries: are there specific indications?].

Twenty-one patients with suspected internal knee joint lesions were examined prospectively. In all patients an MRI was carried out first and was followed within two weeks by an arthrography and an arthroscopy. Lesions of the menisci, cruciate ligaments, hyaline cartilage, and synovial tissues were evaluated. Arthroscopy findings were defined as the "gold standard". MRI achieved an accuracy of 96.4%, a sensitivity of 93.6%, and a specificity of 92.5%, whereas arthrography achieved an accuracy of 67.8%, a sensitivity of 66.6%, and a specificity of 71.4%. These statistical data as well as the single findings revealed no special indications for arthrography in suspected knee joint lesions.

Acute Disease↗
PubMed1994

[The quantitative determination of bone mineral content--a system comparison of similarly built computed tomographs].

An intercomparison of 4 CT scanners of the same manufacturer was performed. The bone mineral content of 11 lumbar vertebral columns removed directly post mortem was determined in a specially constructed lucite-water phantom. Even devices of the same construction were shown to yield a variation in the quantitative evaluation markedly exceeding the annual physiological mineral loss. As long as scanner adjustment by physical calibration phantoms has not yet been established, a course assessment and therapy control of bone mineral content should always be carried out on the same QCT scanner.

Absorptiometry, Photon↗
PubMed1993

Evaluation of vasculogenic impotence by monitoring of cavernous oxygen tension.

Color coded duplex sonography, regarded as the gold standard in penile vascular evaluation, does not yield data on cavernous oxygenation itself. In addition to using color coded duplex sonography to measure peak flow velocity in cavernous arteries after injection of 20 micrograms. prostaglandin E1 in 34 unselected patients with impotence, we monitored cavernous oxygen tension with oxygen-sensitive Eppendorf needle electrode. During flaccidity the mean cavernous oxygen tension of 38 mm. Hg increased to 61 mm. Hg after injection of prostaglandin E1. Peak flow shown with color coded duplex sonography and maximal oxygen tension correlated well in 24 men (71%). However, in 10 men (29%) normal peak flow did not result in a cavernous oxygen tension of greater than 65 mm. Hg, so this might have been isolated cavernous perfusion defects. In contrast, there was no case of impaired arterial inflow and high oxygen tension. Monitoring of cavernous oxygen tension allows for characterization of patients with cavernous perfusion deficiency. This new and simple diagnostic method might help to improve diagnosis and followup after penile vascular surgery. However, more data on patients and controls will be required to define normal ranges.

Alprostadil↗
PubMed1993

[MRT-specific staging of chondromalacia patellae with the aid of a special knee compressor: a comparison with the arthroscopic findings].

The present study proposes a new MRI-specific staging of chondromalacia patellae (CMP) which is based on cartilage thickness decrease and signal intensity behaviour under compression as well as cartilage morphology in the plain image. The investigation was performed in 30 patients with varying knee complaints who underwent arthroscopy after MR imaging. It was demonstrated that three CMP stages can already be differentiated by MRI under compression in arthroscopically healthy cartilage. This proves a marked improvement in the early diagnosis of CMP.

Adolescent↗
PubMed1992

Color-coded duplex sonography in impotence: significance of different flow parameters in patients and controls.

The use of color-coded duplex sonography of the cavernous arteries in the assessment of arteriogenic impotence was evaluated in 70 consecutive men referred for erectile dysfunction. Controls were 16 of the men with an unequivocal nocturnal penile tumescence and rigidity. After intracavernous injection of prostaglandin E1, peak flow velocity was 26.8 +/- 12.5 cm/s in patients and 37.2 +/- 13.0 cm/s in controls (p less than 0.05). 50% of the patients, but none of the controls, had peak flow velocities of less than 20 cm/s in at least 1 cavernous artery. However, within the range of 20-40 cm/s, there was marked overlap between groups. The mean flow velocity and resistance index did not improve the discriminative value of peak flow velocity. Peak flow velocity after intracavernous injection of vasoactive drug enables the discrimination between impotent patients and controls. In a single patient, however, particularly one with a flow velocity of 20-40 cm/s, definition of arteriogenic impotence remains difficult.

Alprostadil↗
PubMed1983

Plasmapheresis in the treatment of psoriasis. A controlled clinical study.

Six patients with long-standing, moderately active plaque/nummular psoriasis were treated with either plasmapheresis or sham-plasmapheresis once weekly for 7 weeks in a double-blind controlled trial. No difference was found between active treatment and placebo. The marginal effect, which might be demonstrated by a larger study, is too small to justify this expensive modality of treatment.

Adult↗