[en] In 15 patients with malignant lymphoma and in a control group of 17 patients, fast MR imaging at 1.5 T, US, and dynamic CT were performed. In eight patients circumscribed lymphatic infiltration of the spleen was seen on MR imaging as a region of low signal intensity, with better contrast between that region and the adjacent tissue than was detected on US or CT. In two patients with splenic infarction regions of high signal intensity were seen, while the US findings were similar to those of lymphatic infiltration. Unlike CT and US, MR imaging in two patients with histologically proved, diffuse lymphatic involvement revealed tissue characteristics different from those seen in the control group

[en] To investigate the potential of contrast material-enhanced MR imaging for the evaluation of focal liver lesions, dynamic and steady-state MR imaging was performed in 20 patients with focal liver lesions. Multisection spin-echo images (repetition time msec/echo time msec = 500/15 and 1,600/22,80) were obtained at 1.5 T before and 10 minutes after intravenous administration of Gd-DTPA. Partial flip-angle images (fast low-angle shot [FLASH], 70⁰/50/10) were acquired before and repeatedly after contrast medium application. The study indicated that steady-state, contrast-enhanced MR images and, in certain cases, dynamic FLASH images did yield useful diagnostic information for the MR imaging evaluation of focal liver lesions

[en] Sixty-eight patients with Crohn disease of the lesser pelvis were studied prospectively with computed tomography (CT) (DR3; Siemens, Erlangen, West Germany), before and after intravenous bolus injection of contrast material. The CT findings were compared to results obtained by means of rectosigmoidoscopy, sinography, ultrasound, and clinical examination. The presence of fistulas was shown in 47 patients by CT and correctly excluded in 27 patients. In 39 patients, CT provided valuable information about the location and extension of the fistulas with respect to the adjacent organs. Contrast material-enhanced CT is now used routinely in the authors' institution for the assessment of patients with Crohn manifestations of the pelvic floor

[en] Sixty-one patients with histologically proved disorders of the prostate underwent MR imaging at 1.5 T, performed using multiecho sequences with eight echoes (TE = 30-240 msec, TR = 1.6 sec). A quantitative criterion that considered the maximum error rate (MER) of confusing normal and pathologic tissue was calculated for each TE and for the T2-weighted images obtained from the multiecho sequences. Between TE = 90 msec and TE = 150 msec, prostatic carcinoma could be best differentiated from normal (MER = 20%-30%) and true compressed prostate in BPH (MER = 25%-35%), while prostatic carcinoma could not be discriminated from BPH. The use of T2-weighted images was useful only in the differentiation of prostatic carcinoma from inflammation or bleeding after invasive procedures

[en] Fifty-one patients with disorders of the upper abdomen underwent MR imaging at 1.5 T using gradient-echo sequences with flip angles of less than 90⁰. Each image was acquired during breath-holding (measuring time, 10 sec.), thus resulting in an excellent display of the normal anatomy. Characteristic flow artifacts, however, disturbed the display of the pancreatic head an lymph nodes. Optimal organ-to-fat contrast was seen at large flip angles, while hepatic and splenic lesions were best depicted at small flip angles. Analysis of signal intensity at different flip angles revealed typical patterns for normal and pathologic tissues and provided a new approach to calculating T1

[en] Experimental results for natural convection in a cavity are reported. Both constrained andd unconstrained cavity geometries were studied. Detailed velocity profiles were obtained using Laser doppler velocimetry for Rayleigh numbers between 3 x 10¹⁰ and 2 x 10¹¹, corresponding to a constant elevated wall temperature boundary condition. Characteristics of two-dimensional and three-dimensional flows obtained with dye flow visualization are discussed, including boundary layer transition to turbulence, flow patterns in the cavity, and flow outside of the cavity. Local Nusselt number is correlated with local Rayleigh number for constrained and unconstrained cavities

[en] Published in summary form only

[en] Aim: To evaluate the impact of interobserver variability in the contouring of gross tumor volumes (GTVs) and clinical target volumes (CTVs) on the global geometric accuracy in radiation therapy. Material and Methods: In a review of the currently available literature, the magnitude of interobserver variability is analyzed, causes and consequences are discussed. Uncertainties due to inconsistencies in contouring are related to other sources of geometric errors, particularly patient positioning and organ motion. Results: Interobserver variability is a major - for some tumor locations probably the largest - factor contributing to geometric inaccuracy. Causes are multifactorial and include image- and observer-related factors, such as the subjective interpretation of image information. Conclusion: Consequences to reduce interobserver variability are proposed, among others the selection of adequate imaging modalities, intensified radiologic training, and the use of telecommunication tools. (orig.)

[en] Purpose: To evaluate the efficacy of radiotherapy in patients with recurrences of cervical carcinoma. Patients and Methods: 26 patients who underwent radiation therapy for recurrences of cervical carcinoma following surgery between 1989 and 1999 were retrospectively analyzed. 17 patients had inoperable or macroscopic residual tumor. Nine patients had a complete/microscopically incomplete tumor resection. Depending on tumor burden and location of the recurrence, external-beam radiotherapy or a combination with brachytherapy was delivered to a total dose of 50-65 Gy. Results: The 5-year overall survival was 28%, relapse-free survival 24%, pelvic control 48%. Therapeutic outcome was related to the margins of resection, location of recurrence and technique of radiotherapy. In case of surgery without residual or microscopic tumor, the 5-year survival rate was 67%, with macroscopic tumor no patient was alive after 37 months (p = 0.05). 5-year overall survival was 42% for central recurrences, 10% for recurrences with pelvic wall infiltration. Recurrences confined to the vagina or paravaginal tissue had a higher 5-year overall probability as compared to all other patients (57% vs. 14%). All patients treated with combined radiotherapy were alive, whereas all patients treated only with external radiotherapy were dead after 32 months (p = 0.01). Conclusion: The probability of controlling recurrence mostly depends on a small tumor burden with the possibility of brachytherapy and/or complete surgery. Aggressive treatment modalities like radiochemotherapy and/or higher radiation doses are needed, especially for recurrences with infiltration of the pelvic wall and/or with macroscopic tumor. (orig.)

[en] Background and purpose: rectal toxicity following external-beam irradiation of prostate cancer correlates with the exposed percentage of rectal volume. Recently, it has been recommended to reduce the volume of the seminal vesicles that should be included in the clinical target volume (CTV). The purpose of this study was to quantitatively assess the impact of this CTV reduction on the expected rectal and bladder dose sparing. Patients and methods: 14 patients with localized prostate cancer undergoing external-beam radiotherapy were investigated. The prostate, the prostate + entire seminal vesicles, or the prostate + proximal seminal vesicles were delineated as CTV. Treatment plans were generated and compared concerning rectum and bladder dose-volume histograms (DVHs). Results: the exposure of rectum and bladder volume was significantly lower in case of irradiation of the prostate only compared to inclusion of the proximal or entire seminal vesicles into the CTV. The reduction of the CTV from prostate + entire seminal vesicles to prostate + proximal seminal vesicles led to a significant reduction of the rectal and bladder dose exposure. Conclusion: reduction of the CTV to the prostate only, or to the prostate + proximal seminal vesicles led to significant rectal and bladder dose sparing compared to irradiation of the prostate + entire seminal vesicles. In patients with a higher risk for seminal vesicles involvement, irradiation of the prostate + proximal seminal vesicles should be preferred. In case of a need for irradiation of the entire seminal vesicles, patients should be informed about a higher risk for chronic rectal toxicity and, possibly, for bladder complications. (orig.)