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PURPOSE: To evaluate whether or not a total dose (TD) of 30 Gy is sufficient for treatment of assumed subclinical Hodgkin's Disease compared to 40 Gy TD with early stage Hodgkin's Disease (ESHD). METHODS AND MATERIALS: In a prospective multicenter trial, 376 patients with laparotomy-proven ESHD stages PS IA to PS IIB without risk factors such as large mediastinum, massive splenic involvement, extranodal disease, elevated erythrocyte sedimentation rate (ESR), and/or three or more involved lymph node areas were randomly allocated either to receive (ARM A) 40 Gy TD extended field-radiotherapy (EF-RT) or (ARM B) 30 Gy TD EF-RT plus 10 Gy TD involved field-radiotherapy (IF-RT), both arms without any chemotherapy. Three hundred sixty-six of these patients were evaluable for early and long-term response, such as remission status, freedom from treatment failure (FFTF), and overall survival (OAS). For quality control, all planning and verification films as well as dose charts were prospectively reviewed by a panel of four experts, all heads of a radiotherapy department, where protocol violations (PV) were seen either with regard to errors in treatment technique, treatment volume, in TD and/or in dose/time-relationship. RESULTS: Treatment resulted in a complete remission (CR) of 98%; in a 5-year FFTF of 76%, and a 5-year OAS of 97%. There was no difference between the two arms in favor of 40 Gy EF compared to 30 Gy EF regarding FFTF and OAS, without any in field relapse throughout the EF volumes. Expectedly, 5-years FFTF was significantly influenced by the quality of radiotherapeutical procedures: 70% with protocol violations (PV) vs. 82% without PV. CONCLUSION: Subclinical involvement in ESHD without risk factors is sufficiently treated by a TD of 30 Gy without chemotherapy, leading to a 5-years FFTF of 82% and a 5-year OAS of 97% in a multicenter treatment setting, where quality assurance is mandatory.

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PURPOSE: The calculation of radiation absorbed dose using a chemical dosimeter and NMR-imaging techniques provides non-invasive 3D dosimetry. The main problems with this new method are measurement accuracy and diffusion effects. These involve influences on chemical preparations, correct data acquisition (evaluation of the T1 values) and a lack of methods for reducing diffusion effects. The aim of this study was to develop a computer assisted localized dosimetry method using fast and quantitative NMR-imaging techniques in order to reduce diffusion effects and to determine the accuracy of this new approach. We show successful localized dosimetry experiments and present a new method for the calculation of the diffusion coefficient. MATERIAL AND METHODS: The dosimeter gel contained a modified Fricke solution and was stabilized with gelatin. Several compositions of dosimeter gels and different conditions were investigated in order to optimize the treatment. IR-Snapshot-Flash has been used to determine the T1-values. The diffusion coefficient of the bound ferric ions was estimated by taking advantage of the short acquisition times of this fast NMR-imaging technique. RESULTS: Dependencies of the dosimeter system were investigated. The calculated error limits for evaluation of the measurement accuracy are in the range of 10 to 20%. The accurate localized determination of the T1-values and the diffusion has considerable influence on the measurement. Fast and quantitative NMR-imaging methods for accurate T1-calculations like IR-Snapshot-Flash reduce this effect. CONCLUSION: Our results show the advantage of the use of fast MR-imaging techniques for NMR Fricke dosimetry. The diffusion effects are reduced effectively, so even details can be imaged. We also developed a new method for the calculation of the diffusion coefficient, which can be used for paramagnetic ions in any aqueous solution.

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PURPOSE: For the precise planning of radiotherapy treatment ports, the delineation and control of their borders has to be performed with X-ray and other imaging procedures before and during the therapy. MATERIALS AND METHODS: Conventional planned therapy ports are checked with the help of MR-imaging with new gel-markers, as a further development to formerly used fluid filled tubes, on the skin of the patient in different regions. We describe the essentials of these gels and report about their first practical use. RESULTS: Principal considerations to the technique and practical applications are given with imaging examples. The essential physical qualities of the gels are introduced with separate NMR experiments. It turns out, that multiplanar MR-imaging in combination with field markers on the skin is a fast simple and useful help for the control and the improvement of treatment planning. CONCLUSION: MR-imaging with gel-markers on the skin in many cases can show the tumor and the field-ports in one picture. Thus the therapy planning is refined with simple means. On the one hand the target volume can be seized completely and on the other hand sensitive organs can better be protected.

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In 33 patients of the multicenter German Hodgkin's Lymphoma Study Group the field borders of the paraaortic field were compared computer-assisted. It was seen that fields are chosen often too small or too large, though precise description of the fields is given in the protocol. In these patients the para-aortics were irradiated exclusively as extended field region. In addition to the above observation the clipping of the spleen pedicle provides the optimal help for correct positioning of this field. Overall a very low frequency of lymphatic clipping is observed, though clinical needs are obvious.

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28 patients with clinically confirmed head and neck tumours were examined by MRI. The results of a dynamic FLASH-2D sequence and a Gd-DTPA enhanced T1-weighted sequence were analysed and retrospectively compared with surgery and pathological findings. The extent of tumours was clearly defined by the dynamic technique in 21 cases. Furthermore, it was found to be superior for the purpose of demonstrating contrast behaviour and concerning T-classification. Here the dynamic FLASH-2D sequence proved to be an important supplement for preoperative diagnosis.

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We developed a verification method that allows the three-dimensional qualitative delineation of the dose inside an applicator during intracavitary brachytherapy using MRI of dose-dependent changes of iron sulphate. In addition to computer calculations, the verification of the dose distribution is depicted now within the applicator. Therefore one can get a qualitative information about the relative position of the applicator according to the tumor volume and the desired brachytherapy radiation volume.

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In patients with advanced breast cancer the incidence of diabetes insipidus is between 0.1% and 0.9%. Satisfactory symptomatic relief can be obtained with Desmopressin-acetate. In the presence of this symptom complex magnetic resonance imaging (MRI) can aid in the detection of metastases to the posterior pituitary. By the use of magnetic resonance imaging, the incidence for and implementation of local radiotherapy can be firmly grounded.

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The Merkel cell tumor is becoming an increasingly diagnosed primary neoplasm of the skin. This subepidermal tumor is commonly located on the head and neck or extremities of elderly patients. Occasionally misinterpreted as cutaneous metastases, they show a high rate of local recurrence (27 to 52%) and distant metastatic spread (18 to 52%). The definitive diagnosis can be made with immunohistochemistry. Wide surgical excision with postoperative irradiation to the local site and regional lymphatics is the therapy of choice. In seven patients we describe management strategies and discuss their clinical results.

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After experiences with fluid filled tubes a gel fitted with an adhesive has been developed, to reproducibly markate treatment ports on the patient's skin. A gel is chosen, that hinders loss of the fluid and smoothly fits to the skin surface due to the adhesive. The clinical use of the gel hopefully will help with the use of NMR image information in radiotherapy treatment planning.

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Fast MR imaging attracts the interest of both clinicians and physicists because new diagnostic information arises with reduced artifacts due to short investigational times. With the acceleration of the Snapshot FLASH MR sequence, the measurement of high-resolution images with 256 x 256 matrix is reported, together with contrasting prepulses that are applied to attain contrast in combination with higher in-plane resolution. Measuring times are in the range of a second. For whole-body imaging, a TR = 5.2 msec and a TE = 2.6 msec could be attained measuring omit 256 x 256 matrix images. Artifact-free images demonstrating T1 contrast and contrast from chemical shift are performed on moving organs (heart, intestine) in different experiments. These applications can easily be performed in a couple of minutes for clinical use. Especially in the lung, short TE and high resolution result in a new imaging quality of pulmonary and mediastinal vessels.

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Advantages of new flexible intracervical applicators treating cervical cancer with high dose rate afterloading brachytherapy are reported: The insertion of the flexible applicator is usually possible without anesthesia and dilation of the cervix. Therefore the treatment can be performed on an outpatient basis. The risks of perforation and infection are minimal. Dosimetry and documentation of the applicator geometry are possible, if the planning system allows the definition of individual curves of an individual applicator. We now prefer flexible applicators instead of rigid steel applicators treating cervix carcinoma.

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Real-time vascular and cardiac magnetic resonance (MR) imaging has been reported only with echo-planar imaging. In this study, the fast low-angle shot (FLASH) MR imaging sequence was reduced to repetition times of 3 msec and echo times of less than 1.3 msec with use of an improved MR imaging system. The resulting 200-msec MR images (64 X 128 pixels) are called snapshot FLASH images. They allow measurements from dynamic series of MR images depicting processes such as relaxation behavior and the cardiac cycle in the absence of motion and flow artifacts. In animal studies (at 4.7 T) and in studies of human volunteers (at 2.0 T), vascular and cardiac snapshot FLASH images were obtained as a single shot, as reconstructed motion, and as real-time movies. The arbitrary and fast T1 contrast of these images and the reduction of motion artifacts result in favorable applications for the depiction of myocardial and great-vessel anatomy. These clinical applications can be performed on conventional MR imagers with minor technical modifications.

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Magnetic resonance imaging (MRI) has several advantages over conventional X-ray methods: the patient is not exposed to radiation; images of any chosen level can be taken without changing the position of the patient; soft tissues are well differentiated; and artefacts due to dental materials are avoided. Thus, in certain fields of ENT diagnosis MRI is superior to computed tomography, for example, in the imaging of acoustic neuromas, glomus tumours and tumours of the parotids, oropharynx and orbit. The measuring time per slice image, which was previously measured in minutes, has been reduced by a factor up to 1000 by the FLASH (fast low angle shot) technique. Thus, it is now possible to follow human physiological processes on an MRI film with a frame speed of 5 pictures using a whole-body magnet. Films of speech, tongue movements and the act of swallowing reveal the value of this technique for the functional diagnosis of disease of the oropharynx. Precise imaging of the anatomical and functional situation, especially of soft tissues, is superior to that of previous methods such as ultrasound, X-ray, and endoscopy.

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SNAPSHOT-FLASH is a recently developed, ultrafast imaging technique, based on conventional FLASH imaging. The application of this new variant to 3D imaging allows the acquisition of a 128 x 128 x 32 data set in 12.5 seconds without triggering, or for cardiac imaging with gating within 32 heartbeats. Compared to standard 3D-FLASH this is 128 times faster, because triggering is only required when the 3D phase-encoding gradient is incremented. The method depicts for the first time fast three-dimensional views of the human heart without motional artifacts. The images are spin-density weighted. Using suitable prepulses any desired T1- or T2-contrast may be achieved. The generation of 3D movies is possible without an increase of the total scan time.

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Snapshot fast low angle shot (FLASH) magnetic resonance (MR) imaging techniques have been developed to enable real time imaging of MR parameters. The method is based on a 64 x 128 FLASH tomogram acquired within less than 200 ms. This work describes snapshot FLASH MR using a single 180 degrees pulse prior to the acquisition of a series of FLASH images. The experiment creates continuous dynamic inversion recovery (IR) T1 contrast in successive images. The total acquisition time of 16 images displaying the IR behavior is less than 4 s. Representative snapshot FLASH IR MR images of the abdomen of healthy rats and of an implanted hepatic tumor are illustrated.

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A simple modification of FLASH (Fast Low Angle SHot) MR imaging, which results in a variable reduction of the intensity of flowing blood and flow artifacts in transaxial tomograms, is reported. Here a nonselective radiofrequency pulse of variable flip angle is used before the acquisition of each projection in FLASH imaging to saturate flowing blood within the whole volume (SYstemic Saturation = SYS-FLASH).

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Nuclear magnetic resonance (NMR) imaging is a promising new technique for non-invasive medical diagnosis. Following a decade of technical improvements and preliminary medical experiences, the measuring time of several minutes remained the major drawback of the method. The recent development of a fast NMR-imaging technique, the so-called FLASH (Fast Low Angle SHot) method, opens a new field of medical applications. This article deals with a few applications and aspects of FLASH imaging. Using the technique cross-sectional images can be taken within a few seconds without loss in spatial resolution. Therefore dynamic investigations of the function of internal organs and images of blood vessels become possible. Furthermore three-dimensional volume imaging of the whole object provides the full anatomical information. FLASH imaging is also applicable in combination with localized NMR-spectroscopy. Thus, biochemical information from NMR-spectroscopy and structural and functional information from NMR-tomography can easily be combined.

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