[Bolus-triggered spiral CT: a new program-monitored procedure for optimal contrast].
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Adolescent↗
Biomedical subjects
R Vosshenrich
Publications and source records attributed to R Vosshenrich.
[An anatomically adapted variation of the tube current in CT. Studies on radiation dosage reduction and image quality].
PURPOSE: To assess the impact of a method for anatomically adapted tube current variation. The resulting CT image quality was evaluated quantitatively and qualitatively. METHODS: CT scans of 100 patients were performed with a constant tube current (Group 1) and another 100 patients with an anatomically adapted tube current (Group 2). The CT tube current was varied during a 360 degrees tube rotation reflecting the measured density values extracted from two perpendicular scout views. The standard deviation of densities of defined regions was measured. The image quality was ranked (1 = non-diagnostic-5 = excellent) by three radiologists. RESULTS: The effective tube current could be reduced by an average of 8.9% (0-20.4%). The mean tube current reduction depended on the body region: pelvis (13.2%), abdomen (8.4%) and thorax (3.3%). The image quality was not significantly reduced in Group 2. CONCLUSION: The method for anatomically adapted tube current variation leads especially in the pelvis to a significant mAs reduction without considerable loss of image quality.
Aged↗
Broadband ultrasound attenuation in the diagnosis of osteoporosis: correlation with osteodensitometry and fracture.
PURPOSE: To evaluate the usefulness of broadband ultrasound attenuation in the prediction of osteoporosis. MATERIALS AND METHODS: Broadband ultrasound attenuation measurements of the calcaneus and dual x-ray absorptiometry (DXA) measurements of the lumbar spine and the femoral neck were obtained in 400 patients (295 female and 105 male), 135 of whom were classified as having osteoporosis. Correlation coefficients between broadband ultrasound attenuation and DXA were calculated. RESULTS: Patients with osteoporosis showed a statistically significant decrease in broadband ultrasound attenuation compared with healthy patients (59.7 dB/MHz +/- 1.3 [standard deviation] vs 75.1 dB/MHz +/- 0.8). Broadband ultrasound attenuation correlated statistically significantly with vertebral bone density (r = .49) and femoral neck density (r = .52). At a broadband ultrasound attenuation index of 64 dB/MHz, the sensitivity and specificity were both 85% for patients with osteoporotic fractures. CONCLUSION: Broadband ultrasound attenuation can be used to help differentiate between patients with osteoporosis and healthy patients and seems to be useful in the prediction of fracture risk.
Absorptiometry, Photon↗
Parenchymal liver enhancement with bolus-triggered helical CT: preliminary clinical results.
A software-driven device for bolus-triggered start of helical computed tomography (CT) was evaluated in liver studies of 30 patients with suspected metastatic liver disease. Compared with results in a control group of 30 patients who underwent conventional contrast material-enhanced helical CT, the study group had significantly higher and more constant parenchymal enhancement (P < .05, Mann-Whitney U test). This technique helps optimize findings at contrast-enhanced helical CT.
Contrast Media↗
MR imaging-guided breast intervention: experience with two systems.
PURPOSE: To evaluate two different systems for magnetic resonance (MR) imaging-guided breast intervention. MATERIALS AND METHODS: Thirty-four patients with 34 lesions detected exclusively with contrast material-enhanced MR imaging underwent 51 interventional procedures (23 needle biopsies and 28 preoperative wire localizations) with two different systems. An add-on device for surface coils was used in 25 cases, and a dedicated single breast biopsy coil was used in 26. For needle biopsies, material was aspirated with nonmagnetic 19.5-gauge needles. For preoperative localizations, nonmagnetic hook wires were used. RESULTS: Surgical excision or follow-up verified the cytologic findings in 19 of the 23 cases sampled for biopsy. Cytologic diagnosis was impossible in three of the 23 cases. One technical failure occurred with the biopsy coil. Open biopsy performed after MR imaging-guided localization successfully removed 26 of the 28 lesions. One missed carcinoma was found at repeat localization and removed. One technical failure occurred with the biopsy coil. In that case, the lesion was close to the chest wall. CONCLUSION: Both systems are suitable for fine-needle biopsy and preoperative localization of lesions seen exclusively on MR images.
Adult↗
Value of magnetic resonance imaging in patients with penile induration (Peyronie's disease).
Magnetic resonance imaging (MRI) is a noninvasive procedure that enables exact imaging of penile anatomy. A total of 34 patients with clinical Peyronie's disease underwent palpation, ultrasound and MRI after intracavernous injection of 10 micrograms. prostaglandin E1. MRI images were obtained before and after intravenous application of gadolinium-diethylenetriaminepentaacetic acid. In 34 patients 45 plaques were palpable. Ultrasound revealed evidence of lesions in 66.6% of the cases. On MRI 36 of 45 palpable plaques (80%) were detected. Not palpable or sonographically revealed indurations could be shown in 4 cases. After intravenous application of gadolinium-diethylenetriaminepentaacetic acid 4 plaques demonstrated contrast enhancement, thus indicating local inflammatory activity. The combination of clinical examination and sonography remains the method of choice for diagnosis and observation of patients with Peyronie's disease. MRI enables exact imaging of penile structures but it does not provide a significant advantage over standard investigative procedures.
Adult↗
[Signal characteristics of x-ray contrast media and their interaction with gadolinium-DTPA in MRT].
T1 and T2 weighted signals derived from various radiological contrast media were studied during MRT spin-echo sequences. In addition, the interaction between radiological contrast media and Gadolinium-DTPA concerning T1 signals was evaluated. Ionic (ioxitalaminic acid) and non-ionic radiological contrast media (Iopromid, Iotrolan) were used in diagnostic concentrations. Measurements were carried out with a superconductive magnet of 1.5 Tesla. Radiological contrast media produced significantly higher signals than a physiological sodium chloride solution in T1-weighted spin-echo sequences. Even small amounts (15% of total volume) of radiological contrast media during T1-weighted spin-echo sequences led to a significant reduction (about 25%) of the signal intensity of a 2 mM Gadolinium-DTPA solution. This may lead to diagnostic problems, as was shown in a series of 25 MR arthrograms of the shoulder. It is recommended than an interval of at least 6 hours should elapse between the use of a radiological contrast medium and an MRT examination.
Contrast Media↗
[The determination of the T2* relaxation time for characterizing trabecular bone].
Spongy bone produces local magnetic field inhomogeneities and leads to shortening of the transverse relaxation time from bone marrow. This increased signal decay affects the T2 relaxation time. Measurements of the T2* time from the 4th lumbar vertebra were carried out in 48 normals and 20 patients with osteoporosis. A special multigradient echo technique was used, the echo times selected in relation to phase coherence of the water and fat signals. T2* times showed slight increase in relation to age. Patients with osteoporosis showed significantly increased T2* times (19.9 +/- 3.8 ms) compared to the normal control group (13.4 +/- 1.9 ms). From these findings it is possible to judge the quality of the trabecular structure.
Adult↗
[Preoperative MR-mammography in diagnosed breast carcinoma. Useful information or useless extravagance?].
In a retrospective study the value of MR mammography in cases of radiological well-known carcinoma of the breast was evaluated preoperatively in 76 cases of histopathologically verified carcinoma one lesion was missed by MR imaging. Compared to the results of conventional X-ray mammography additional malignant lesions were detected in 5 patients ipsilaterally and in another 8 patients contralaterally by MR mammography only. In additional 4 cases MR mammography demonstrated suspicious lesions contralaterally, but histopathology revealed benign lesions. The therapeutic procedure was changed in 15 cases (18.5%) due to the findings of MR imaging: Ipsilateral mastectomy instead of tumorectomy (n = 5) or primary chemotherapy instead of operation (n = 1); contralateral additional tumorectomy (n = 3) or mastectomy (n = 2) by carcinoma and open biopsy (n = 4) by benign finding.
Adult↗
[Inflammatory lesions of the breast: indication for MR-mammography?].
In a retrospective study the value of MR imaging of the breast in inflammatory changes was evaluated. The signal enhancement of 8 patients with histopathologically verified inflammatory carcinomas and 9 patients with global mastitis as well as local inflamed lesions was analysed. Neither signal behaviour nor signal/time relation were suitable to differentiate between malignant and benign changes. In conclusion inflammatory changes of the female breast are not indicated to be examined with MR imaging.
Adenocarcinoma↗
Investigation of the imaging properties of an x-ray film scanner.
In this note, the imaging properties of a CCD x-ray film scanner were investigated. The relationship between optical density and the logarithm of output pixel value provides information on the linearity of the system. The resolution properties of the scanner can be characterized by the presampling modulation transfer function which was calculated from a set of line spread functions with various alignments relative to the sampling grid. Our results show that the scanner is linear up to 2.0 optical density units, which leads to restrictions in digitizing x-ray films with higher optical density. The measured MTF shows the good spatial resolution of the CCD scanner which is demonstrated on an example.
Equipment Failure Analysis↗
MR-guided biopsy of suspect breast lesions with a simple stereotaxic add-on-device for surface coils.
A guiding attachment is described that transforms a conventional magnetic resonance (MR) imaging surface coil into a stereotaxic biopsy unit. Eight patients, aged 38-66 years (mean, 54 years), with suspect breast lesions detected exclusively at contrast material-enhanced MR imaging underwent MR-guided needle biopsy with this unit. Diagnostic material was successfully aspirated in all patients (four carcinomas, three fibroadenomas, and one intraductal hyperplasia), and the diagnosis was subsequently confirmed at surgical biopsy. This technique promises to increase the diagnostic specificity for lesions seen solely at MR imaging.
Adult↗
Malignant priapism in a patient with metastatic prostate adenocarcinoma.
Metastases to the penis due to a primary carcinoma of the prostate are rare. In approximately half of the patients, malignant priapism is the main symptom. This study reports on a case of malignant priapism, caused by a direct and metastatic infiltration of the corpora cavernosa by a prostatic adenocarcinoma. Sonography gave hints, the magnetic resonance imaging verified the infiltration and aspiration cytology verified the carcinoma. Hemodynamics, evaluated by Doppler sonography, and intracavernosal blood gas analysis demonstrated a mixed high-low priapism without need of therapy.
Adenocarcinoma↗
Dissection of the thoracic aorta: pre- and postoperative findings on turbo-FLASH MR images obtained in the plane of the aortic arch.
This pictorial essay illustrates the pre- and postoperative findings seen in patients with aortic dissections on contrast-enhanced turbo-fast low-angle shot (FLASH) MR images obtained in the plane of the aortic arch. Contrast-enhanced images provide morphologic and functional information not normally available with conventional spin-echo (SE) MR imaging or dynamic CT. Preoperative examination of the acute dissection is often troubled by cardiovascular insufficiency and motion artifacts. Therefore most of our patients were examined postoperatively. The main reason for postsurgical imaging is the evaluation of the flow in the different lumina and the detection of complications (i.e., aneurysms or progress of dissection).
Aortic Dissection↗
Kidney preservation in situ and conservative treatment of renal cell carcinoma: application of HTK solution (CUSTODIOL).
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Adolescent↗
[MR angiography of peripheral blood vessels].
MR angiography (MRA) of the extremities is in its infancy. The potential appears to be great, but several problems have to be solved before MRA can routinely be used as the definitive diagnostic procedure. MRA can detect arterial stenoses, occlusions, and determine their length. The degree of stenosis, however, is overestimated. Although the spatial resolution of MRA allows depiction of the tibial vessels, evaluation of their major branches is necessary for distal bypass surgery. The postoperative examination of patients with bypasses seems to be a practical alternative with regard to the established angiography techniques. At present, MRA is cost-effective, but not as readily available as conventional angiography. MRA technology continues to advance rapidly. With improved technology, judicious use, and appropriate patient selection, in the future MRA should assume a role in the evaluation of peripheral arterial occlusive disease.
Arterial Occlusive Diseases↗
[Signal characteristics of malignant and benign lesions in dynamic 2D-MRT of the breast].
In a retrospective study of 400 dynamic MR examinations of the breast the signal/time ratio of 62 histopathologically correlated lesions (19 benign, 42 malignant) was evaluated. Points of evaluation were initial signal enhancement (1st and 2nd minute), post-initial signal appearance (2nd to 5th minute) and signal distribution (homogeneous, marginal). Based on these criteria, a point system was defined to help in the assessment of lesions in dynamic breast-MR imaging. The overall sensitivity of this method was 95.3%, the specificity to 89.5% and the accuracy to 93.5%. Pitfalls resulted in two cases of non-invasive carcinoma and in two patients with fibroadenoma.
Adenofibroma↗
[The use of the RACE technique for quantitative flow measurements. Evaluation using a clinically relevant flow model].
A phantom has been designed for measuring flow velocities; using pipes of specified diameter and selectable pulse rates, flow rates varying from 0-250 cm/s can be determined. The measurements are made in a superconductive magnet with a field strength of 1.5 Tesla, employing a RACE technique. The reference technique was electromagnetic flow measurement. There was good linear correlation between the electromagnetic and the MRT results with a correlation coefficient of 0.98. It is necessary in the first place to estimate flow speed; if flow velocity is unknown initially, there is no correlation. Hence, in everyday use erroneous results may be obtained, particularly since one cannot always demonstrate vessels in all parts of the body without superimposition. Further clinical studies are required in various vascular territories to evaluate the usefulness of the RACE technique for flow measurements.
Electromagnetic Phenomena↗