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Non-invasive detection of small temperature changes (1 degree C) is pivotal to the further advance of regional hyperthermia as a treatment modality for deep-seated tumours. Magnetic resonance (MR) thermography methods are considered to be a promising approach. Four methods exploiting temperature-dependent parameters were evaluated in phantom experiments. The investigated temperature indicators were spin-lattice relaxation time T1, diffusion coefficient D, shift of water proton resonance frequency (water PRF) and resonance frequency shift of the methoxy group of the praseodymium complex (Pr probe). The respective pulse sequences employed to detect temperature-dependent signal changes were the multiple readout single inversion recovery (T One by Multiple Read Out Pulses; TOMROP), the pulsed gradient spin echo (PGSE), the fast low-angle shot (FLASH) with phase difference reconstruction, and the classical chemical shift imaging (CSI). Applying these sequences, experiments were performed in two separate and consecutive steps. In the first step, calibration curves were recorded for all four methods. In the second step, applying these calibration data, maps of temperature changes were generated and verified. With the equal total acquisition time of approximately 4 min for all four methods, the uncertainties of temperature changes derived from the calibration curves were less than 1 degree C (Pr probe 0.11 degrees C, water PRF 0.22 degrees C, D 0.48 degrees C and T1 0.93 degrees C). The corresponding maps of temperature changes exhibited slightly higher errors but still in the range or less than 1 degree C (0.97 degrees C, 0.41 degrees C, 0.70 degrees C, 1.06 degrees C respectively). The calibration results indicate the Pr probe method to be most sensitive and accurate. However, this advantage could only be partially transferred to the thermographic maps because of the coarse 16 x 16 matrix of the classical CSI sequence. Therefore, at present the water PRF method appears to be most suitable for MR monitoring of small temperature changes during hyperthermia treatment.

Fragestellung: Die vorliegende Studie untersucht die Wertigkeit der Elektronenstrahlcomputertomographie (EBT) bei der pra- und postinterventionellen Abklarung von Pathologien des arteriellen und portalvenosen Gefassystems. Methodik: Innerhalb eines Jahres wurden 40 Patienten mit transjugularem portosystemischem Shunt (TIPS), 12 Patienten mit peripherer arterieller Verschluskrankheit (pavk) und 8 Patienten mit infarenalen Bauchaortenaneurysmata nach interventioneller Therapie prospektiv im EBT untersucht. Im Anschlus an die Untersuchung wurden Zeit-Dichte-Kurven und 3D-Rekonstruktionen der zu beurteilenden Gefasabschnitte angefertigt. Die Ergebnisse wurden mit Befunden der Dopplersonographie und/oder DSA korreliert. Ergebnisse: Bei 30/40 TIPS-Patienten stimmte die EBT mit der Dopplersonographie bzw. der DSA uberein, bei 3 Patienten konnte eine dopplersonographisch nachgewiesene und interventionell bestatigte Minderperfusion des TIPS im EBT nicht diagnostiziert werden. Bei 9/12 Patienten mit angiographisch nachgewiesenen Gefasstenosen (>75%) konnte eine Abflachung und ein verzogerter Anstieg der Zeit-Dichte-Kurven nachgewiesen werden. Die Quantifizierung der Stenose mit den Zeit-Dichte-Kurven zeigte jedoch nur eine eingeschrankte Korrelation mit der i.a.-DSA. Bei den Patienten mit endovaskular implantierter Aortenprothese konnte in allen Fallen eine komplette Ausschaltung des Aortenaneurysmas nachgewiesen werden. Schlusfolgerung: Die Vorteile der FBT bestehen in der Moglichkeit, zusatzlich zur „konventionellen” kontrastverstarkten Schnittbilddiagnostik aufgrund der methodisch bedingten hohen zeitlichen Auflosung auch dynamische Aspekte zu erfassen. Mogliche klinische Indikationen im Bereich des abdominellen Gefassystems bestehen insbesondere in der postinterventionellen Untersuchung zur Uberprufung des Interventionserfolges.

Background Recent studies show that preoperative radio-chemotherapy can increase resectability and local control of locally advanced rectal carcinomas. Additional regional hyperthermia might increase remission rates and tumor response. We therefore tested regional hyperthermia together with radio-chemotherapy in a phase-II study on locally advanced rectal carcinomas. Patients and methods Thirty-seven patients with primary advanced stage uT3/T4 rectal carcinomas were treated with preoperative radio-chemo-thermo-therapy. The initial tumor depth was determined using endosonography, CT, and MRI. Radiotherapy was carried out in prone position (on a belly board) using standard techniques, with 5 x 1.8 Gy per week up to 45 Gy at the reference point. 5-Fluorouracil (300 to 500 mg/m2) was administered with low doses of leucovorin (50 mg) on days 1 to 5 and 22 to 28. The patients were treated with regional hyperthermia each week prior to radiotherapy and simultaneously with chemotherapy, using the Sigma 60 ring from the BSD-2000 system. Temperature/position curves and temperature/time curves were recorded in endocavitary (endorectal) catheters in tumor contact and as well in bladder and vagina. Following endosonographic restaging, the operation was carried out 4 to 6 weeks after the end of preoperative therapy and adjuvant chemotherapy continued in four cycles. In cases where tumors were non-resectable, a boost up to 64 Gy was aimed. Results Thirty-one of the 37 patients (84%) with primary carcinoma proved locally R0-resectable. In addition we had 1 R1-resection (3%) and 5 non-resectable tumors (13%). Among the resected tumors, 53% experienced a reduction of depth infiltration from the initial endosonographic stage during preoperative therapy. The actuarial survival rate after 4 years is 65% (free of progression 57%). The actuarial 4-year survival rate was particularly favorable for the group of responders. Overall, the preoperative multimodal therapy was well tolerated, and premature termination was only necessary in 1 case (3%). Grade III/IV toxicities in the intestine and skin were reduced as far as possible by field blockings and cooling of the perineal region. They occurred only in 5/37 patients (13%) at the intestine and in 6/37 patients (16%) at the skin. The thermal data were subjected to a statistical analysis. The quality of temperature distribution (T90, cum min T90 > or = 40.5 degrees C) depends on the power level and relative power density. The response (reduction of tumor size or depth infiltration) correlated significantly with quality parameters of the temperature distributions. This dependency is found as a trend for progression-free survival, too. Conclusions Preoperative radio-chemo-thermo-therapy proved to be practical and effective, with encouraging remission rates and excellent local control rates. For this reason, a phase-III study to test regional hyperthermia has been initiated. At the same time, certain technical improvements are still under development for regional hyperthermia.

To evaluate the use of high-resolution magnetic resonance imaging (MRI) for the differentiation of skin tumors in the maxillofacial region, 60 patients (25 female) were examined in a 1.5-T whole-body MR imager with a 2.5-cm surface coil. Plain transverse T1-(TR 500 ms, TE 25 ms), T2-(2200 ms, TE 80 ms), fat-(TR 500 ms, TE 28 ms), and water-suppressed (TR 500 ms, TE 38 ms) SE sequences were used. Following the application of the paramagnetic contrast agent Gd-DTPA, transverse T-weighted and fat suppression sequences were repeated. Before and after contrast administration, tumor signal intensities and percent contrast enhancement were determined by a ROI technique. All tumors were classified by standard histologic technique and evaluated with regard to their response to contrast medium. Quantitative evaluation was performed by three independent radiologists. Additionally, signal- and contrast-to-noise ratios were calculated for each tumor type. All MRI findings were compared with histology. Significant contrast enhancement occurred in most tumors; malignant tumors displayed inhomogeneous enhancement. The optimal pulse sequences for tumor delineation are plain T1-weighted, water-suppressed, and contrast-enhanced fat-suppressed sequences. Tumors could not be specified by signal intensities or percent contrast enhancement, and CNR did not allow for malignant lesions to be differentiated from benign tumors. High-resolution MRI proved to be an adequate method for imaging skin tumors and their inner structure. Tumor typing was not possible by either contrast-administration or modification of sequence parameters. In this regard, further innovations in contrast agent design seem to be necessary.

Objective: To determine whether the quality of infiltrations in chest radiographs can accurately predict the histological extent of fibrotic change in patients with acute respiratory distress syndrome (ARDS). Design: Retrospective clinical investigation. Setting: Intensive care unit (ICU) of a university teaching hospital. Patients and methods: Of 47 patients treated with extracorporeal membrane oxygenation (ECMO) for severe ARDS over a 5-year period, 23 patients underwent open lung biopsy at thoracotomy for treatment, mostly of pneumothorax. Chest films obtained by portable chest roentgenography preceding the operation were reviewed retrospectively and compared to the histomorphological results of the lung specimen. Results: Chest radiographs displayed mixed alveolar-reticular opacification in 60.2 %, alveolar patterns in 22.9 % and reticular opacities in 10.5 %. In 0.4 % there were no infiltrates, 6 % could not be evaluated because of insufficient quality. There was no relevant difference between the right and left lungs. Subdividing patients into two groups according to the histological results of either absent or mild (1) or severe (2) lung fibrosis, we found an alveolar haziness in 12.3 % in group 1 compared with 28.2 % in group 2, while reticular characteristics were identified in 13 % and 11 %, respectively. Conclusions: The most common opacity in chest radiographs of patients with severe ARDS treated with ECMO is mixed alveolar-reticular opacification. Severe lung fibrosis is not positively correlated with a reticular radiographic pattern. ECMO does not lead to specific radiological changes in conventional radiograms, contrary to clinical findings that treatment with ECMO might induce pleural or pulmonic haemorrhage, especially in the earlier days when systemic heparinization had to be used instead of the heparin-coated tube-surfacing.

To evaluate experimentally and clinically an internally cooled power laser system for percutaneous treatment of liver metastases, with magnetic resonance (MR) imaging guidance, to increase the volume of coagulative necrosis with single laser beam applications.The power laser system consisted of standard cannulation paraphernalia and a specially designed 7-F protective catheter for cooling the laser tip during treatment to avoid carbonization. A microdome laser beam applicator with a laser tip diameter of 0.95 mm kept the entire device as small as possible. After the unit was tested in 40 porcine livers, 532 laser beam applications (mean power, 27.5 W [range, 22.1-30.0 W]; mean application time, 19.8 minutes [range, 14-30 minutes]) were performed with MR guidance in 127 patients with 318 liver metastases. The safety of the procedure and the volume of induced necrosis were evaluated.In vitro, cuboid areas of coagulative necrosis with a mean greatest diameter of 4.3 cm +/- 0.5 (SD) were demonstrated after single applications. In vivo, MR thermometry allowed accurate demarcation of changes induced by heat, with a mean diameter of necrosis of 3.3 cm +/- 1.4. No carbonization or vaporization of tissue or damage of equipment occurred during treatment.This power laser system can increase the volume of laser-induced necrosis in liver metastases with a single application, thereby simplifying and accelerating the treatment of larger lesions.

Ziel: Die Segmentierung und 3D-Rekonstruktion anatomischer Strukturen in Schnittbildern erzielt haufig, bedingt durch Artefakte infolge des Partialvolumeneffektes (PVE), nur suboptimale Ergebnisse. Diese Storungen sollen durch Einsatz der morphologischen Bildverarbeitungsoperatoren (MO) Erosion und Dilatation reduziert werden. Methode: Bei 31 Patienten mit pathologischen Veranderungen in Lunge bzw. Gehirn wurden die CT-Daten mittels Regionenwachstum automatisch segmentiert und die MO mit einer unterschiedlichen Anzahl an Iterationsschritten angewendet. Die so bearbeiteten CT-Daten wurden dreidimensional rekonstruiert (MIP, Oberflachendarstellung, Volume Rendering) und anschliesend das Auftreten von Artefakten anhand des Signal/Hintergrund-Verhaltnisses (SBR) vor und nach Anwendung der MO verglichen. Ergebnisse: Bei allen ausgewerteten Patienten konnten durch die Bilderosion schon mit einer geringen Zahl von Iterationen Storungen durch PVE signifikant herabgesetzt werden (Lunge: mittleres SBRpre=1,67, SBRpost=4,83; Gehirn: SBRpre=1,06, SBRpost=1,29). Mit der Regionendilatation konnten in einer definierbaren Umgebung um die Ausgangsregion weitere Strukturen (z.B. an der Tumoroberflache) in die Darstellung integriert werden. Schlusfolgerungen: Die MO stellen ein wirkungsvolles Verfahren zur Reduktion der Auswirkungen von PVE-Artefakten in 3D-CT-Rekonstruktionen dar und gestatten eine optimierte Visualisierung einzelner Objekte.

Ziel: Bei dynamischen Kontrastmittel- (KM) Studien konnen spezifische Merkmale der Zeit/Intensitats-Kurve (ZIK) eines jeden Bildpunktes verwendet und in Form von Parameterbildern dargestellt werden. Aufbauend auf bestehenden Konzepten der zweidimensionalen Analyse der KM-Dynamik soll eine dreidimensionale Erweiterung mit adaquater computergraphischer Visualisierung realisiert werden. Methode: Bildgebung: Intravenose KM-Injektion; First-pass-Analyse mit CT bei schneller Akquisition einer einzigen Schicht; Untersuchung der langerfristigen KM-Anreicherung mit 40 MR-Schichten (6 Sequenzen alle 90 s=240 Bilder). Softwareentwicklungen: ZIK beliebiger ROIs/VOIs; Parameterbilder: 1. Maximum-Intensitats-Projektion (TMIP) aller Pixel als Funktion uber die Zeit; 2. zeitliche KM-Gradienten (TG) anhand der ZIK-Amplitude; 3. ZIK-Steigung/Gefalle; 4. Zeitpunkte der ZIK-Maxima; 5. Korrelationskoeffizienten zu Vergleichs-ZIK. Die berechneten 3D-Daten der KM-Anreicherung wurden mittels multiplanarer Reformatierung, MIP, Oberflachenrekonstruktion, Volume Rendering und Textur-Mapping visualisiert und animiert. Ergebnisse: TMIP und TG erlaubten bei First-pass-Analysen die simultane oder getrennte Prasentation unterschiedlicher Zeitraume des KM-Bolus. Die Korrelationsbilder gestatteten die Hervorhebung von Regionen, die Ahnlichkeiten zu vorgegebenen ZIK-Mustern aufwiesen. Computergraphische Techniken gestatteten 1. ein anatomisch/funktionales Mapping von Originalbild und KM-Anreicherungsverhalten sowie 2. die fusionierte Darstellung von KM-Anreicherungsbetrag und farbkodierter Zeit des KM-Maximums in einem gemeinsamen Bild. Schlusfolgerungen: Die exakte Quantifizierung von Prasenz, Grad und Ankunftszeit des Kontrastmittels in lokalen Bildregionen unterstutzt die Beurteilung der Vaskularisation sowie von ischamischen bzw. nekrotischen Arealen.

Both dacryocystography and dacryoscintigraphy are well established in the evaluation of stenoses of the lacrimal drainage system. They provide limited information about the ductal anatomy itself and about periductal structures. MR imaging was evaluated for its capability to directly visualize the lacrimal drainage system in detail and simultaneously provide functional characterization of dacryostenosis. Subjects and methods: Twenty-seven lacrimal drainage systems of 23 patients suffering from epiphora were examined in an MR unit before and after conjunctival and intravenous application of Gd-DTPA using a surface coil. Results: Dacryostenosis was found in 23 of 27 lacrimal systems. Stenoses were localized to the canalicular (n = 3), saccular (n = 8), and ductal (n = 12) level, and were classified as stenosis or occlusion. Conclusion: MR imaging with conjunctival contrast application allows within one examination both detailed morphological and functional assessment of the lacrimal drainage system with depiction of surrounding structures. Limitations arise mainly from demands on technical and patient-related preconditions.

Purpose: Invasive thermometry for regional hyperthermia is time-consuming, uncomfortable, and risky for the patient. We tried to estimate the benefit/cost ratio of invasive thermometry in regional hyperthermia using the radiofrequency system BSD-2000. Methods and Materials: We evaluated 182 patients with locally advanced pelvic tumors that underwent regional hyperthermia. In every patient a tumor-related temperature measurement point was obtained either by invasive or minimally invasive catheter measurement tracks. In the earlier period for every patient an intratumoral measurement point was decided as obligatory and intratumoral catheters were implanted intraoperatively, CT guided, or under fluoroscopy. In the later period, invasive thermometry often was avoided, if a measurement point in or near the tumor was reached by an endoluminally inserted catheter (rectal, vaginal, cervical, urethral, or vesical). For every patient side effects and complications referred to thermometry were evaluated and compared with the potential benefit of the invasively achieved temperature data. The suitability of endolumimally registered temperatures is analyzed to estimate local feasibility (specific absorption rate achieved) and local effectiveness (thermal parameters correlated with response). Results: In 74 of 182 patients invasive thermometry was performed, at most CT-guided for soft tissue sarcomas and rectal recurrences. In 14 of 74 (19%) side effects such as local inflammation, pain, or abscess formation occurred that enforced removal of the catheter. However, local problems were strongly correlated with the dwell time of the catheter and nearly never occurred for dwell times less than 5 days. Fortunately, no fatal complications (e.g., bleeding or perforation) occurred during or after implantation which could be attributed to the invasive thermometry procedure. Endoluminal tumor-related temperature rises per time unit (to estimate power density) were correlated with intratumoral rises at the same patients (where both measurements were available). For a subgroup of patients pooled in two Phase II studies with rectal ( n = 37) and cervical ( n = 18) carcinomas thermal parameters derived from endoluminal measurements were correlated with response or local control, resp. Conclusions: If a tumor-related endoluminal temperature measurement point is available, additional invasive thermometry gives no further information to improve the power deposition pattern. For primary rectal and cervical cancer, and probably as well for prostate, bladder and anal cancer, endoluminal measurements are suitable to estimate local feasibility and effectiveness. Therefore, invasive thermometry is dispensable in the majority of patients. In some selected cases, temperature measurement in the tumor center is required to estimate the maximum temperature. In those cases, dwell time of catheters should be minimized—and it should be considered to perform invasive thermometry at the beginning (one or two heat treatments).

In der vorliegenden Untersuchung werden die Spiral-CT und die konventionelle CT im Hinblick auf die axiale und radiale Dosisverteilung miteinander verglichen. Es soll untersucht werden, wann eine Erhohung des Tischvorschubs bei der Spiral-CT eine Dosisreduktion bewirkt. Zur Abbildung der Dosisverteilung wurden Filme in einem Plexiglasphantom exponiert. Die nominelle Schichtdicke betrug 5 mm, der Schichtabstand bei der konventionellen CT 5 und 10 mm, der Tischvorschub bei der Spiral-CT 5 und 10 mm pro Rotation (Pitch 1 und 2). Die vom Tischvorschub bzw. Schichtabstand abhangigen integralen Dosen bei der Spiral-CT und der konventionellen CT wurden rechnerisch miteinander verglichen. Die Spiral-CT zeigte geringere Dosisschwankungen in axialer Richtung als die konventionelle CT. Nur bei der konventionellen CT mit einem Schichtabstand von 5 mm wies die axiale Dosisverteilung in der Nahe der Rotationsachse relative Spitzenwerte auf. Mit Zunahme der Lange der Untersuchungsregion wird der zur Dosisreduktion erforderliche Tischvorschub kleiner. Ab einer Lange von 15 Schichtdicken fuhrt eine Erhohung des Pitch auf >1,1 bereits zu einer Reduktion der integralen Dosis gegenuber der konventionellen CT. Die Kontinuitat des Tischvorschubs bei der Spiral-CT fuhrt zu gleichmasigerer axialer Dosisverteilung als die diskontinuierliche Abtastung bei der konventionellen CT. Die Spiraltechnik kann einen wichtigen Beitrag zur Dosisreduktion in der Computertomographie leisten.

RATIONALE AND OBJECTIVES. The authors correlate computed tomography (CT) findings in biphasic spiral technique with histopathology in patients with hepatocellular carcinoma (HCC) who had undergone liver resection (LR) or orthotopic liver transplantation (OLT). METHODS. Preoperative biphasic spiral CT findings in 33 consecutive patients (23 men, 10 women, aged 43-74 years; LR group: n = 17; OLT group; n = 16) with liver cirrhosis and HCC were reviewed retrospectively by consensus of two radiologists and correlated with pathology from liver specimens. RESULTS. Of the 16 patients in the OLT group with 1 to 5 confirmed HCC lesions (total lesions: 29; mean lesion diameter: 2 cm; range: 0.6-5.0 cm), CT before OLT depicted 22 lesions in 15 patients (sensitivity for lesions with a diameter of 0.5-1.0 cm, 20%; for lesions 1.1-2.0 cm, 82%; and for lesions 2.1-3.0 cm and >3.0 cm, 86% and 100%, respectively). Among the 17 patients in the LR group (total lesions: 21; mean lesion diameter: 5.4 cm; range: 1.0-11.0 cm), CT detected 18 lesions. Lesion-by-lesion sensitivity, as correlated with pathology, was calculated at 76% and 86% in the OLT and LR groups, respectively (overall sensitivity, 80%). The diameter of CT detected lesions, compared with liver specimens, corresponded in 90% of lesions (maximum deviation, 15%). Characteristic CT findings of HCC included unenhanced hypoattenuating focal liver lesions (32 lesions), with hyperattenuation (38 lesions) in the arterial phase of contrast material administration. CONCLUSIONS. Biphasic spiral CT for preoperative HCC detection correlated with pathology in 80%, thus proving this technique to represent a sensitive imaging modality for pretherapeutic evaluation of HCC.

OBJECTIVE: A prospective phase II study was performed to determine the feasibility and efficacy in terms of response rate, resectability, and morbidity in patients with locally advanced rectal cancer who received preoperative regional hyperthermia combined with radiochemotherapy (HRCT). SUMMARY BACKGROUND DATA: Recent studies suggest that preoperative radiochemotherapy in locally advanced rectal cancer can induce downstaging, but after resection the incidence of local recurrences remains high. Hyperthermia (HT) may add tumoricidal effects and improve the efficacy of radiochemotherapy in a trimodal approach. PATIENTS AND METHODS: Thirty-seven patients with histologically proven rectal cancer and T3 or T4 lesions, as determined by endorectal ultrasound and computed tomography, entered the trial. 5-Fluorouracil (300-350 mg/m2) and leucovorin (50 mg) were administered on days 1 to 5 and 22 to 26. Regional HT using the SIGMA 60 applicator (BSD-2000) was given once a week before radiotherapy (45 Gy with 1.8-Gy fractions for 5 weeks). Surgery followed 4 to 6 weeks after completion of HRCT. RESULTS: Preoperative treatment was generally well tolerated, with 16% of patients developing grade III toxicity. No grade IV complications were observed. The overall resectability rate was 32 of 36 patients (89%), and 31 resection specimens had negative margins (R0). One patient refused surgery. In 5 patients (14%), the histopathologic report confirmed no evidence of residual tumor (pCR). A partial remission (PR) was observed in 17 patients (46%). The survival rate after 38 months was 86%. In none of the patients was local recurrence detected after R0(L), but five patients developed distant metastases. CONCLUSION: Preoperative HRCT is feasible and effective and may contribute to locoregional tumor control of advanced rectal cancer, which is to be proven in an ongoing phase III trial.

Background/aims: An experimental model for the preclinical evaluation of contrast enhancement patterns in melanoma was developed. Methods: Melanotic and amelanotic tumor cells B16F1 and B16a implanted into murine skin were depicted with magnetic resonance imaging (MRI) at a pixel size of 78×78 urn and 1 mm slice thickness. Tumor signal intensities were evaluated in user defined ROIs (regions of interest). Signal intensity changes were determined from signal intensity-time curves. Percent enhancement, slope of the signal intensity curve and percent signal intensity increase were also determined. Percent enhancement was calculated: (SIenhanced-SIpiain)/SIplain× 100 [SI=signal intensity]. The slope of the signal intensity curve was calculated: (SImax-SIplain)/(SIplain× SImax) × 100 (%/min). Percent signal intensity increase was calculated: (SImax-SIplai)/SIplain× 100. Results: Following i.v. administration of Gd-DTPA and G-DTPA-polylysine, all tumors showed pronounced contrast enhancement. Contrast enhancement and the slope of signal intensity to time curves did not distinguish melanotic from amelanotic melanomas (P>0.05). Conclusions: The animal model presented is well suited for evaluation of contrast enhancement in melanoma by MRI. Contrast enhancement of melanoma in MRI is comparable with the enhancement seen in other tumors.

The aim of this study was to establish whether an increase of maximum Doppler shift occurs in the human common carotid artery after the administration of Levovist, an ultrasonographic echo enhancer. Twenty common carotid arteries of 10 patients were examined. Spectral Doppler waveform examinations were performed before and after administration of Levovist using an Acuson 128 XP 10 and a 7.0 MHz transducer probe. Time averaged mean velocity, peak velocity, maximum Doppler shift, and spectral Doppler indices (pulsatility index, resistive index, systolic-diastolic ratio) were assessed. No significant changes in any of the measured parameters, including maximum Doppler shifts, peak velocity (P = 0.35, Wilcoxon rank sum test), pulsatility indices (P = 0.70), resistive indices (P = 0.98), or other spectral indices, were found. We conclude that an increase in Doppler shift does not inevitably occur after the administration of a signal enhancer when examining the human common carotid artery.

This article shows the results of an experimental investigation of the interference by paramagnetic and diamagnetic materials on imaging in a closed 1.5 Tesla high field magnetic resonance imaging system (MRI). For different types of sequences (SE, GE, EPI) the effects of metal and non-metal profiles in producing artefacts were investigated. A phantom (plastic trunk) filled with Gd-Mn-solution was used for representation of the artefacts. The materials analysed were placed parallel to the phantom at predetermined distances. The images were obtained in transverse and sagittal planes and analysed with respect to the resulting artefacts. The results show that aluminum and polymer profiles produce the weakest artefacts, even when the material is positioned close to the phantom. A comparison of the sequence types shows that the SE-sequence has a low sensitivity to artefacts, despite the great profile variation in size and shape. The SE-sequence accordingly showed a higher imaging stability as compared with the GE- and EPI-sequences. Steel and copper produced the strongest artefacts. The examination was begun after an intensive study of the literature (Internet, Medline, Meditec). So far have been few publications on this subject.

SummaryThis study evaluates the potential of MR-guided laser-induced thermotherapy for the treatment of recurrent head and neck tumours, as a stand-alone method, or in combination with radiotherapy. 15 patients with recurrent head and neck tumours (recurrent squamous cell carcinoma n=13, recurrent pleomorphic adenoma n=2) were treated, using MR-controlled laser-induced thermotherapy. 18 lesions were treated with 25 laser applications. MR thermometry was performed, using a temperature-sensitive TurboFLASH (TR/TE/TI = 7/3/400; flip angle = 8d`) and FLASH-2D (TR/TE/flip angle = 102/8/70d`) sequence for monitoring thermal-induced changes in signal and morphology. T1 weighted (TR/TE=700/15) sequences, plain and contrast-enhanced, were used for follow-up. 14 patients tolerated the procedure well. In one patient, with a recurrent squamous cell carcinoma and infiltration of the sublingual gland, the treatment had to be stopped after 5 min due to pain. No long-term side effects related to treatment were observed. ...

In recent years, the finite-difference time-domain (FDTD) method has found numerous applications in the field of computational electromagnetics. One of the strengths of the method is the fact that no elaborate grid generation specifying the content of the problem is necessary-the medium is specified by assigning parameters to the regularly spaced cubes. However, this can be a weakness, especially when the interfaces between neighboring media are curved or "sloped" and do not exactly fit the cubic lattice. Since the E- and H-fields are only calculated at the regular intervals, sharp field discontinuities at the interfaces are often missed. Furthermore, the averaging of the material properties often leads to significant errors. In this paper, a post-processing method is presented, which approximates the correct field behavior at the interfaces by interpolating between the FDTD calculated values, splitting them into the components normal and tangential to the interfaces, and then enforcing the interface conditions for each of these components separately.

Purpose: HIV-infected patients show a high incidence of abdominal disease. This investigation was made to determine whether abdominal CT provided prognostically relevant information in these patients Material and Methods: Images from 533 abdominal CT examinations in 339 HIV-infected patients were retrospectively reviewed for signs of abdominal disease, and correlated with clinical data and survival rates. the Kaplan-Meier analysis and rank testing of survival, and proportional hazards regression were used to define prognostic clinical and imaging findings Results: of the 339 patients, 278 (82%) showed abnormal abdominal findings on CT. Median survival was 29 months. of the imaging findings, hepatic masses (n=11), pathologically enlarged lymph nodes (n=48), and ascites (n=7) were associated with poor survival, giving a median survival of respectively 13 months, 15 months, and less than 1 month. These three features showed no association with CD4+-T-lymphocyte count or CDC category. Main determinants of survival were a low CD4+-T-lymphocyte count, and certain abnormal CT findings. Splenomegaly (n=147), hepatomegaly (n=144), and lymphadenopathy (n=111) were the most common abdominal findings on CT but lacked prognostic relevance Conclusion: Abdominal CT offered prognostic implications in HIV-infected patients and might serve in risk stratification in selected patients. CT features such as hepatic masses, grossly enlarged lymph nodes, or ascites indicate advanced immunosuppression

Intestinal symptoms affect most AIDS patients at some point in their disease. The purpose of this study was to evaluate the use of CT in this setting. A total of 339 abdominal CT exams were reviewed for signs of intestinal disease. Abdominal CT scans of 45 patients with intestinal symptoms were compared with colonoscopy and histologic data. The CT results were correlated with CD4( +) T-lymphocyte counts and patient survival. More than 14 % of all abdominal CT exams displayed signs of enteric disease. Of the 45 patients studied with both CT and colonoscopy, 35 (78 %) had signs of intestinal disease by CT. Of these 35 patients, colonoscopic signs of an intestinal lesion were found in 29 and histologic proof of disease was established in 30 cases. Colonoscopy and histology detected 8 lesions missed by CT. There were 14 cases of unspecific colitis, 15 cases of cytomegalovirus (CMV) colitis, and 4 cases of enteric tuberculosis as per biopsy. Five patients presented with Kaposi's sarcoma and 1 with a non-Hodgkin's lymphoma. Neither colonoscopic nor CT signs of intestinal disease did reliably distinguish between histologic subgroups. Specifically, CMV colitis could not be distinguished from unspecific colitis. CD4( +) T-lymphocyte counts for histologic subgroups were not significantly different, either. No colonoscopic or histologic feature predicted survival, whereas low CD4 counts and ascites on CT indicated a poor prognosis. Whereas CT detects signs of intestinal disease in most AIDS patients, these signs remain largely unspecific. Colonoscopy and biopsies provide no consistently valid standard with which to compare CT because of controversial sensitivity and specificity of these methods. The CT technique detects small bowel as well as extraintestinal disease. Therefore, CT is an important diagnostic modality in abdominal disease of immunocompromised patients.

To assess the value of the peripheral washout sign on delayed contrast material-enhanced magnetic resonance (MR) images in differentiation of benign from malignant breast masses.In 49 women with 79 breast lesions (55 malignant and 24 benign), dynamic contrast-enhanced MR imaging was performed every 90 seconds during the first 7 minutes and repeated at 10, 20, 30, 40, 50, and 60 minutes after injection of contrast material. Qualitative analysis of the images was performed to evaluate the presence of the peripheral washout sign (a hypointense zone in the periphery of the lesion relative to the center). Quantitative analysis of the images was performed by measuring the signal intensity of the periphery and center of the lesions.The peripheral washout sign was seen in 28 (51%) of the 55 carcinomas on delayed contrast-enhanced MR images (10 minutes). Quantitative analysis demonstrated different enhancement profiles of the periphery and center of these lesions. The periphery showed early increase and decrease of enhancement, while the center showed gradual increase and persistent enhancement. The peripheral washout sign was not seen in any of the benign lesions. Specificity was 100% and sensitivity was 51% for diagnosis of breast carcinoma.Peripheral washout may be a reliable sign of malignancy on delayed contrast-enhanced MR images of the breast.

In order to evaluate patients' exposure to radiation in computed tomography, dose quantities such as the computed tomography dose index (CTDI), multiple scan average dose (MSAD) and dose free in air on the axis of rotation are used. The CTDI and the MSAD, derivable from the CTDI, are a good measure for the absorbed doses in the examined volume, but they do not take the biological sensitivity of the organs into account and do not describe the radiogenic risk that is actually relevant for patients and doctors. The dose on the axis of rotation is not an accurate measure of the effective dose and the radiogenic risk. The declaration of a limit for the dose on the axis of rotation should take the different regions into account, in order to guarantee acceptable image quality on one hand and to avoid an unnecessarily high risk on the other side. As physical dose quantities, the CTDI, MSAD and dose on the axis of rotation are useful to characterize and differentiate between programs and systems concerning radiation exposure.

Our objective was to evaluate the accuracy of contrast-enhanced transrectal MR imaging in staging rectal adenoma and carcinoma by correlating with histopathologic findings.Thirty-five patients underwent transrectal MR imaging on a 1.5-T superconducting unit using unenhanced T1-weighted and T2-weighted spin-echo and turbo spin-echo sequences, a dynamic gadopentetate dimeglumine-enhanced turbo fast low-angle shot sequence, and enhanced T1-weighted spin-echo sequences. For all patients, histopathologic correlation was available from biopsy (n = 15) or surgical resection (n = 20). Two radiologists unaware of each other's interpretations of the scans interpreted each case from which we evaluated qualitative and quantitative data.Rectal adenomas (n = 15) were identified when imaging revealed an intact muscularis mucosae, a homogeneous internal structure, and high contrast enhancement of the lesion. Carcinomas staged as T1 by TNM criteria (n = 6) were best revealed by dynamic turbo fast low-angle shot sequences, in which an intact muscularis propria could be seen. Visualization of enhancing tumor tissue in the muscularis propria indicated T2 carcinoma (n = 5). All T3 (n = 5) and T4 (n = 4) carcinomas were correctly staged with dynamic and static MR imaging. The stage revealed by MR imaging correlated well with histologic staging results in 89% (observer 1) and 86% (observer 2) of interpretations. However, when interpreting MR imaging, observers tended to overstage and never understaged.Transrectal surface-coil MR imaging provided reliable information in staging patients before surgery and in evaluating rectal adenoma and carcinoma.

Ziel dieser Studie war die Uberprufung der Wertigkeit von hochauflosenden T2-gewichteten TSE-Sequenzen fur die Darstellbarkeit normaler anatomischer und pathologischer Strukturen im Bereich des Innenohres und des inneren Gehorgangs. Insgesamt wurden 30 Probanden ohne klinische Symptomatik und 73 Patienten mit den klinischen Zeichen einer Innenohrerkrankung an einem 1,5-Tesla-MRT-Gerat mit der Kopfspule untersucht. Es kamen neben den konventionellen T2- und T1-gewichteten Sequenzen stark T2-gewichtete hochauflosende TSE-Sequenzen (TR/TE=4797/400) in transversaler und sagittaler Schichtorientierung zum Einsatz. Aus den transversalen TSE-Datensatzen wurden MIP-Rekonstruktionen angefertigt. Bei allen Probanden und 59 von 73 Patienten kamen die Kochlea, die Canales semicircularis lateralis, anterior und posterior sowie die Nervi facialis, cochlearis, vestibularis superior und inferior regelrecht zur Darstellung. Bei Patienten mit einem intrameatalen (n=3) oder intra-/extrameatalen (n=2) Akustikusneurinom gelang es, die exakte Lagebeziehung zwischen Tumor und nervalen Strukturen zu dokumentieren. Bei einem Patienten, der fur eine Kochlea-Implantation vorgesehen war, zeigte sich eine Aplasie der Nervi cochlearis, vestibularis superior und inferior. Dieser Patient wies zudem eine Aplasie des Canalis semicircularis lateralis rechtsseitig auf. Bei einem Patienten mit einem Vestibularisneurinom zeigte sich eine Aplasie des Canalis semicircularis lateralis und posterior. Die hochauflosende MRT des Innenohres ermoglicht die exakte Darstellung normaler anatomischer und pathologischer Strukturen im Submillimeterbereich in einer Untersuchungszeit von 15 bis 20 min. Die MIP-Rekonstruktionen erlauben eine deutliche und prazise Darstellung der flussigkeitsgefullten Strukturen des Innenohres.

As proteins are integrated into the membrane of the endoplasmic reticulum, some hydrophilic polypeptide segments are transported through the translocation channel, others remain in the cytosol, and hydrophobic transmembrane sequences are released into the lipid phase. We have addressed the molecular mechanism by which these events occur. We demonstrate that both the lumenal and the cytosolic domains of a membrane protein are synthesized while the ribosome is membrane bound, so that even cytosolic domains come in contact with the translocation channel. We also find that, before translation of the protein is terminated, transmembrane sequences can laterally exit the translocation channel and enter the lipid environment. These results have significant implications for the folding and assembly of membrane proteins.

The mechanism of left ventricular outflow tract (LVOT) obstruction in the patient after mitral valve replacement or repair was examined with the aid of 2D echocardiography. For the interpretation of the spatial relationship between the aortic root and mitral annulus, however, the 2D display is sometimes inadequate since it may not simultaneously capture these structures in each center. We developed a method to clarify this relationship in 3D based on magnetic resonance images. We defined the office of the left ventricular outflow tract (LVOT orifice), consisting of, in turn, a muscular region, i.e., edge of the interventricular septum, and an annular region, i.e., the annulus of the anterior mitral leaflet. In this paper we present image data obtained from one of eight normal subjects examined and compare this with data of one of two patients who preoperatively suffered degenerative mitral regurgitation and subsequently underwent chordal-preserving mitral valve replacement, in which anterior chordae were reattached to the anterior annulus. In the normal subject, the mitral annulus exhibited a flexible change in shape during the systole, maintaining sufficient LVOT orifice size. In the patient, the prosthetic valve exhibited translational motion during systole, resulting in dynamic LVOT obstruction. This phenomenon was also observed in one other case. Furthermore, the lateral view of the LVOT orifice revealed a projection of the prosthetic valve into the LVOT, causing mechanical LVOT obstruction. The finding that translational motion of the prosthetic valve with an inflexible mitral annulus results in dynamic LVOT obstruction may support the hypothesis that annular rigidity causes dynamic LVOT obstruction after mitral valve repair with a rigid prosthetic ring.

The application of Doppler-tipped guide wires to measure blood flow velocity in coronary and peripheral arteries has been described previously as a valuable means of functional assessment in interventional cardiological procedures. In animal studies intravascular Doppler has been used in the cerebrovascular system, and this appears to be an important field of application for this new technique. We used intravascular haemodynamic monitoring by the Doppler guide wire during neuroendovascular procedures in patients with different cerebrovascular diseases and evaluated the clinical feasibility of the method. We found it a safe technique which complements morphological angiographic information with valuable functional data. Further studies may be expected to demonstrate the relation of flow parameters to clinical outcome.

Hintergrund Patienten mit fortgeschrittenen Lymphknotenmetastasen bei Kopf-Hals-Tumoren im Stadium N2/N3 (das heist UICC IV) stellen ein groses therapeutisches Problem dar. Trotz kombinierter Radiochemotherapie und hyperfraktionierter und/oder akzelerierter Fraktionierungsschemata ist die lokale Kontrolle dieser Tumoren unbefriedigend. Daher wurde der Stellenwert der lokalen Radiowellen-/Mikrowellenhyperthermie bei dieser Patientengruppe in einer Phase-I/II-Studie gepruft.

Aim: Recent developments of the Internet (World Wide Web) allow the integration of audio, video, digital film sequences, and three-dimensional data. The applicability of these innovations for medical documentation is demonstrated. Methods: Our existing software for medical image processing and 3D reconstruction was extended to provide images, film sequences, and complex 3D models in an Internet-compatible data format. Results: The multimedia results of the image processing were integrated into Internet documents. Specialized programs are no longer necessary for visualization. The Internet software allows for user-friendly handling and interactive presentation of the 2D and 3D data. Conclusions: The Internet offers public-domain software for display of images, audio/video, and 3D data. Thus, the tools of the Internet represent an ideal basis for local hospital information systems, computer-aided medical education, and teleconferencing.

Ziel: Anhand von In-vivo-Untersuchungen war die Schnittbildanatomie der Haut hinsichtlich ihrer bislang unbekannten Erscheinung im hochauflosenden Magnetresonanztomogramm (MRT) zunachst qualitativ und quantitativ zu charakterisieren. Anschliesend sollte der Wert der MRT hinsichtlich der Hautdickenmessung anhand eines Vergleiches mit histologischen Schnitten analysiert werden. Methodik: In einer prospektiven Studie wurde die Haut von 84 Personen mit Hilfe eines 2,5 cm grosen Spulenkopfes in einem Ganzkorpertomographen (Gradientenfeldstarke: 1,5 T) bei einer linearen Auflosung von 100 μm untersucht. Zur Bewertung der Abgrenzbarkeit verschiedener Hautstrukturen wurden nach visueller Charakterisierung deren Signal-Rausch- und deren Kontrast-Rausch-Verhaltnisse objektiviert und ein Vergleich mit histologischen Praparaten vorgenommen. Ergebnisse: Mit der Hochauflosungsspule lassen sich Epidermis, Dermis und Subkutis differenzieren (p

A model system of perfused human colon adenocarcinoma cells (HT29) encapsulated in alginate was used to examine metabolic response to heat therapy with 31P NMR spectroscopy, HPLC and cell survival analysis. The presented data show, that perfused (medium flow during hyperthermia) and non-perfused (no medium flow during hyperthermia) cells are very difficult in their sensitivity to hyperthermia. Under equivalent experimental conditions with respect to medium pH, oxygen and nutrient concentration, encapsulated perfused HT 29 cells display a significantly lower thermal sensitivity than non-perfused cells. This reduced sensitivity of perfused cells is characterized by an increased cell survival and relative ATP concentration, and reduced drop of the NTP/Pi ratio in the long-term follow up towards zero. The relative ATP concentration determined by HPLC after hyperthermia is correlated with the clonogenic survival fraction. There is a direct relationship, depending on the specific experimental conditions (perfused, non-perfused). For perfused cells only a slight dependency of survival and relative ATP concentration on heat dose is observed. In consequence, the correlation between survival and relative ATP concentration is weak, described by log(SFperf) = 0.7*[ATP-12.4, R2 = 0.79, p0.04. For non-perfused cells the correlation is stronger resulting in a relationship of log(SFno perf) = 0.6*[ATP]-9.0, R2 = 0.98, p0.0002. Altogether, the presented data suggest that the relative ATP concentration measured by HPLC after hyperthermia might be predictive for cell survival. On the other hand, a dependence between cell survival and long-term changes of NTP/Pi has been found. The results confirm the importance of tumour perfusion for hyperthermia-induced metabolic changes and cytotoxicity and therefore, for the therapeutic outcome.

The purpose of our research was to determine the effects of superparamagnetic iron oxide on MR imaging of the portal venous system. Eight piglets were examined in deep anaesthesia and respiratory arrest using a time-of-flight magnetic resonance fast low angle shot, two-dimensional angiography sequence at 1.5T, MR angiograms were acquired precontrast and after intravenous administration of a cumulative dose of 10, 20 and 40 mumol/kg SHU 555A, a superparamagnetic iron oxide contrast agent for MR imaging with a particle size of 60 nm. For each dose, two subsequent sets of scans were obtained and reconstructed by a maximum-intensity-projection algorithm. Hepatic parenchymal and portal venous signal intensities were measured, and portal vein contrast calculated for each set of scans. All examinations were visually rated as to portal vein contrast and homogeneity by two blinded observers. Receiver operating characteristics of both observers were analyzed. The contrast agent reduced hepatic parenchymal signal in a dose-dependent way. After a cumulative dose of 10 mumol iron oxide, hepatic parenchymal signal intensity decreased to 63 +/- 6% (average of measurements at 4 and 14 minutes, mean +/- standard error of the mean), after 20 mumol to 24 +/- 3%, and after 40 mumol to 12 +/- 1% of control. Intravascular signal in the left main portal vein branch increased to 117 +/- 6%, 127 +/- 10%, and 133 +/- 9% of control, respectively. The contrast-to-noise ratio of the portal vein improved (521 +/- 90%, 891 +/- 178%, and 995 +/- 201% of control in the left portal vein main branch). Intravascular signal intensities increased slightly. The combined effect improved contrast of the portal vein stem and its branches. Receiver operating characteristics analysis documented dose-dependency of contrast medium effects on portal venous contrast and intravascular homogeneity. Visual rating also indicated a positive effect on portal venous contrast. The superparamagnetic iron oxide agent improved portal venous contrast with surrounding hepatic parenchyma in this normal animal model, and could potentially result in more accurate diagnosis of portal venous pathology.

Magnetic fluids (MF) have a potential for hyperthermia due to their good power absorption capabilities. Recent in vitro experiments with the so-called 'Magnetic Fluid Hyperthermia (MFH)' have shown that human tumours cells are homogeneously inactivated after AC magnetic field excitation of extracellular MF. The aim of the present study was the evaluation of a high dose MFH on intramuscularly implanted mammary carcinoma of the mouse. The tumours originated from initial in vivo passages of a spontaneous parent tumour. Because of larger variations of tumour growth in this rather primary model, logistic regression of non-averaged volumes was performed for each treatment modality. All growing tumours were randomized 30 days after transplantation (day of treatment) with an overall size distribution between 120-400 mm3. An intratumoural steady state temperature of 47 +/- 1.0 degrees C was maintained for 30 minutes with whole-body AC magnetic fields of 6-12.5 kA/m at 520 kHz. The magnetic fluid was #P6, which is a high biocompatible dextran magnetite. #P6 was given intratumourally (1.5 x 10(-2) mg ferrite/mm3) 20-30 minutes before excitation and was combined with magnetic targeting (50 mT), which yielded a 2.5-fold enhancement of the intratumoural iron concentration. Histological examinations of tumour tissue after intralesional ferrofluid administration alone indicated deep infiltration of the fluid into the carcinoma tissue, but no evidence of tissue damage as compared with untreated controls. In contrast, widespread tumour necrosis was observed after MFH. After application of either dextran or ferrofluid alone (no difference, p = 0.665), tumour growth was slightly delayed in comparison with untreated controls (p0.001). In contrast to the good fit of the controls (R = 0.92-0.87), tumour growth after MFH was much more heterogeneous; some tumours showed no evidence for regrowth at 50 days whereas others had grown quite readily. This most probably reflected the critical problem of homogeneity of the intratumoural MF distribution, which was also confirmed qualitatively by Magnetic Resonance Imaging (MRI), heterogeneous pigmentation of MFH treated tumours, and up to 1 degree C differences between temperature probes in the same tumour during AC magnetic field application. However, a quantitative comparison between intratumoural MF-heterogeneity and tumour response could not be performed in this study. Despite these current limitations, the regression analysis of the MFH data yielded a smaller tumour volume of about 1000 mm3 at 50 days growth time in contrast to all three controls. In conclusion, encouraging results have been obtained, which show, that one single high dose MFH is already able to induce local tumour control in many cases within 30 days after treatment. To overcome the uncertainties of intratumoural MF heterogeneity, advanced intralesional application methods are currently under development.

RATIONALE AND OBJECTIVES Fourier phase mapping of cine cardiac magnetic resonance (MR) imaging offers noninvasive analysis of temporal cardiac activation patterns. The aim of our investigation was to extend this analysis to intramyocardial dynamics. METHODS A fast-imaging with steady-state precision (FISP) two-dimensional gradient echo spatial modulation of magnetization (SPAMM) sequence and a segmented two-dimensional FISP-SPAMM sequence were applied to acquire cine MR images of the complete cardiac cycle on a 1.5-tesla imager. Signal intensity data were submitted to pixel-wise Fourier phase analysis. Color-encoded amplitude and phase maps were displayed for visual analysis. RESULTS Using the unsegmented SPAMM two-dimensional FISP sequence, a more consistent tag-to-myocardium contrast and a higher number of cardiac phases was achieved than by using the segmented version of this sequence. The typical tag displacement reflected complex intramyocardial dynamics, including rotation. Phase mapping displayed a pattern of contraction consistent with electrophysiologic concepts of cardiac activation. In contrast, the segmented sequence did not reflect any differences in the onset of cardiac contraction, although tag displacement was apparent with this sequence as well. CONCLUSIONS. Fourier phase mapping of cardiac MR imaging tagging studies allows for noninvasive analysis of intramyocardial activation patterns. A temporal resolution of 50 mseconds per image at a heart rate of 75 beats per minute allows for an assessment of spatial differences in the onset of myocardial activation.

The clinical significance of incidental white-matter foci seen on MRI is controversial. Mainly using a computer-assisted neuropsychological test battery, we tested the hypothesis that there is a clinical correlate of these foci. We studied 41 individuals aged 45-65 years with no history of neurological or psychiatric disorder, in whom no indication of central nervous system abnormalities was found on standardised neurological examination. A computer-assisted neuropsychological test battery, with the advantage of precise measuring of both time and deviation (e.g. in position memory tests), and rating scales for emotional dysfunction were administered; selected soft neurological signs were assessed. In 16 subjects (39%) MRI showed high-signal foci in the white matter on spin-echo sequences. White-matter foci not adjacent to the lateral ventricles were found to be related to performance on immediate visual memory/visuoperceptual skills, visuomotor tracking/psychomotor speed and, to a lesser degree, learning capacity and abstract and conceptual reasoning skills. Subtle cognitive dysfunction would appear to be a clinical correlate of punctate white-matter foci on MRI of otherwise "healty" individuals.

Rationale and objective The authors performed a retrospective study in ultrasound to investigate new aspects in the sonomorphology of lymph node metastases of the neck. In this study, it could be demonstrated the first time that the histologic characteristics of the metastases determine the sonographic appearance. In addition to criteria such as the longitudinal/ transversal quotient, sonomorphology could support a more precise differential diagnosis of neck lymph nodes. Methods In 105 of 145 patients with histologically proved head and neck carcinomas, 187 lymph node metastases were detected by ultrasound. Sonomorphology was compared with the corresponding histology. Results Five sonomorphologic groups could be differentiated. (1) Thirty-one percent of the metastases were homogenous. (2) Concerning the more complex morphology of lymph node metastases in ultrasound, echolucent forms could be differentiated from echogenic textures: low- or nondifferentiated and nonkeratinizing metastases appeared echolucent and cyst-like, with dorsal signal amplification. (3) Nonkeratinizing lymphomas with necrosis showed single or multiple echolucent intranodal lesions. (4) In correlation with an increasing keratinization, the echogenecity of the lymph nodes increased and intranodal echogenic inclusions appeared. (5) An extended keratinization correlated with a central echogenecity. Conclusions The morphologic assessment of lymph nodes in ultrasound allows for primary histologic and prognostic evaluation of lymph node metastases.

Starting with the solution of Maxwell's equations based on the volume integral equation (VIE) method, the transition to a volume-surface integral equation (VSIE) formulation is described. For the VSIE method, a generalized calculation method is developed to help us directly determine E fields at any interface combination in three-dimensional (3-D) electrically inhomogeneous media. The VSIE implementation described is based on separating the domain of interest into discrete parts using nonuniform tetrahedral grids. Interfaces are described using curved or plane triangles. Applying linear nodal elements, a general 3-D formulation is developed for handling scatter field contributions in the immediate vicinity of grid nodes, and this formulation is applicable to all multiregion junctions. The special case of a smooth interface around a grid node is given naturally by this formulation. Grid nodes are split into pairs of points for E-field calculation, and node normals are assigned to these points. The pairs of points are assigned to the elements adjoining the grid node. For each pair of points, the correct field jumps on the interface are given by a surface integral over the polarization surface charge density.

To investigate the application of a mini-coil surface system for high-resolution MRI, 60 volunteers were examined in a 1.5-T whole-body scanner. Two replaceable probe heads were available: a circular 2.5-cm coil and a quadratic 5-cm coil, both of which were placed directly on the skin. The skin layers, Achilles tendon and finger joints were examined with the 2.5-cm coil and a FOV of 25 × 25 mm2. A matrix of 256 × 256 pixels resulted in a pixel size of 0.098 × 0.098 mm2. For imaging of the carpal tunnel, the 5-cm coil was used in transverse orientation. The FOV was 50 × 50 mm2 so that a matrix of 256 × 256 pixels led to a pixel size of 0.195 × 0.195 mm2. The resulting spatial resolution permitted visualization of the epidermis, dermis and subcutis, resulting in clear definition of anatomical detail of the musculoskeletal system. MRI measurement of skin-layer thickness did not correlate with histometric data (p

Purpose: Patients with advanced head and neck carcinomas, primarily nonresectable as well as recurrent cases, were treated in multimodality regimens with radiotherapy, chemotherapy, and local hyperthermia. Commercially available microwave and radiowave applicators were used in 50 patients with N2/N3 cervical lymph node metastases during more than 250 heat treatments. To assess technical suitability, the achieved power densities and thermal parameters were tested for correlation with anatomical and geometrical factors. To assess effectiveness, the response was compared with derived parameters of the achieved temperature distributions. Methods and Materials: The temperature measurement points (in thermometry catheters) documented by computerized tomography are labeled according to tissue depth, shielding by osseous structures, and location in relation to the external applicators. Relative and absolute specific absorption rates (SAR) and cooling coefficients are extracted from the temperature-time curves. Time-averaged temperature-position curves are evaluated to obtain index temperatures (T 90 , T 50 , T 20 ), minimum/maximum tumor temperatures, cumulative minutes T 90 ≥ 43°C, and 43°C-equivalent min T 90 . Radiation dose, treatment time, and chemotherapy regiment are also considered. A response parameter is defined using the pre- and posttherapeutic tumor volumes. A multivariate variance analysis is performed for the dependent variables power density, thermal parameters, and response. Results: A significant correlation exists between power density and absorption, presence of a fat layer, and applicator illumination. The maximum depth is 5 cm, where SAR of ≥ 10 mW/g are registered. Achieved temperatures at individual measurement points are dependent on the SAR, and to a lesser extent, the perfusion-dependent cooling coefficients, but the index temperature T 90 is only significantly related to intratumorally achieved SAR. The thermal gradient (T 20 -T 50 ) and temperature peak (T 20 )_are significantly influenced by the tumor volume. The response is directly related to the index temperature T 90 , equivalent minute T 90 43°C, and cumulative minutes T 90 ≥ 40.5°C, and inversely related to the tumor volume. Conclusions: Local hyperthermia using microwave and radiowave applicators in the head and neck region is a tolerable and clinically practical supplementary therapy used as part of multimodal regimens, and has already been proven to be effective. However, the analyses also demonstrated the limits of currently available technology, and confirm the need for continued methodical research.

SummaryInterstitial laser-induced thermotherapy (LITT) is a recently developed, minimally invasive technique for local tumour destruction within solid organs. The purpose of this study was to evaluate the potential of MR-guided laser-induced thermotherapy (LITT) for the treatment of recurrent head and neck and liver tumours in a prospective study. In the head and neck study 12 patients with recurrent head and neck tumours were treated using MR-con-trolled laser-induced thermotherapy. In the liver study 76 patients with in total 171 histologically-proven liver metastases of colorectal carcinoma, oesopha-geal, gastric, pharyngeal, testicular and Pancoast tumours were treated with LITT. A total of 527 applications were performed. All procedures were tolerated under local anaesthesia with no clinically relevant side effects. MR thermome-try clearly demonstrated an area of signal loss with a radius of up to 15 mm in the vicinity of the laser tip. Dynamic gadolinium-enhanced MRI is suitable for early and late f...

Suspensions of coated superparamagnetic particles (magnetic fluids, MF) in AC magnetic fields have a pronounced specific absorption rate (SAR) per mass compared to multidomain particles. The aim of the present study was to investigate cellular uptake and the biological effects of AC magnetic field excited bio-compatible magnetic fluids on human carcinoma cells in vitro. One of the fluids tested was a dextran magnetite, which has a very low cyto-toxicity with survival fractions (SF) between 0.8 and 0.9 at concentrations of up to 5 mg ferrite per ml. Human carcinoma cells intracellularly accumulate up to 1 pg ferrite/cell which has been demonstrated by electron microscopy (TEM), X-ray spectroscopy and measurements of intracellular iron. It has been shown that the ferrite core is not altered intracellularly, but many of the dextran shells are degraded which yields particle chains and other aggregates observed in TEM. Semi-solid pellets of the tumour cells were treated with AC magnetic fields (520 kHz, 4-12.5 kA/m) or waterbath hyperthermia at 43 and 45 degrees C, in presence of extracellular and/or intracellular magnetic fluid particles. Although MF heating is produced from individual particles, the survival fractions of MF heated and water bath heated cells are equal. In fact, the extracellular MF particle distribution is homogeneous enough to obtain similar inactivation. In contrast to earlier reports intracellular dextran magnetite particles in AC magnetic fields did not induce cell inactivation. Since the amount of intracellular ferrite should be indeed large enough for cell inactivation, the loss of dextran shells is most probably the main cause of limited effectiveness of the intracellular magnetite particles. The present work has demonstrated that: (1) MFH is able to inactivate tumour cells in vitro to at least the same extent as water bath hyperthermia; and (2) that there is a sensitizer effect of ferrofluids at 43 degrees C probably caused by free ferric ions which induce oxidative stress; and (3) that there is no cytotoxic effect of intracellular dextran magnetite particles 30-180 min excited with AC magnetic fields used in this study. For the new method the term 'magnetic fluid hyperthermia (MFH)' is proposed.

RATIONALE AND OBJECTIVES To present a mathematic approach for the analysis of first-pass gadolinium (Gd)-DTPA kinetics and to validate the numerical tools using simulated and measured kinetics. METHODS In a capillary plasma filter, pulsatile flow was varied between 7.4 and 12.6 mL/second. After contrast bolus injection, the arterial input curve and the residue curve were recorded simultaneously. Signal intensity versus time curves were converted to concentration versus time curves. By deconvolution of these curves and tracer kinetic analysis, the mean transit time of the contrast medium through the organ model was calculated. RESULTS A satisfactory correlation (r = 0.98) between the inverse of mean transit time and flow measured volumetrically was demonstrated. CONCLUSIONS The kinetic analysis of first-pass curves in an organ model indicates that this approach might be useful for in vivo assessment of organ blood flow.

ZusammenfassungZiel der Studie war die Darstellung der striatalen Dopamin-D2-Rezeptordichte bei 6 Patienten mit Morbus Parkinson und bei 3 gesunden Probanden mit Hilfe der 123I-Lisurid-SPECT. Im weiteren sollte die Möglichkeit von Rezeptorverdrängungs-Untersuchungen mit Hilfe der Kombination aus 123I-Lisurid mit nichtmarkiertem Lisurid geprüft werden. Entsprechend der Verteilung der Dopaminrezep-toren und in Übereinstimmung mit anderen Studien zeigte sich bei Patienten und bei Probanden die höchste zerebrale Anreicherung von 123I-Lisurid im Striatum. Bei 2 Patienten konnte eine spezifische Rezeptorverdrängung des Radioliganden 123I-Lisurid durch nichtmarkiertes Lisurid dokumentiert werden. Die 123I-Lisurid-SPECT ist zur Darstellung der Striatalen Dopamin-D2-Rezeptordichte in vivo geeignet. Inwieweit Rezeptorverdrängungs-Untersuchungen für die Beurteilung dynamischer Veränderungen der Rezeptoraffinität sowie für die Abschätzung der Anzahl belegter bzw. freier Bindungsstellen geeignet sind, muß durch weitere Studien mit größeren Fallzahlen verifiziert werden.

Hyperthermia can play a role in curative multimodal therapies of locally advanced malignancies. Firstly, the downstaging rate can be increased in pre-operative therapies (resectability, organ preservation), and secondly the local control can be improved. The synergistic effect of hyperthermia at 42-43 °C when combined with radiotherapy has been demonstrated in pre-clinical studies and in phase III studies as well. Furthermore, there are interactions with numerous cytotoxic drugs and un-specific as well as specific immunological processes, the value of which for clinical application has not yet been determined. The future of the clinical use of hyperthermia will be determined to a large extent by developments and improvements in the technology used, and the greatest potential lies in advancing radiofrequency equipment. Infrared whole-body hyperthermia also made progress in the past few years. We outline oncological concepts to apply hyperthermia for advanced rectal carcinomas, carcinomas of the bladder, oesophageal carcinomas and soft-tissue sarcomas. In this work we summarise results relating to hyperthermia performed on these tumour entities and details of possible therapeutic strategies. We also look at technical approaches to improved quality control of the heat delivery device, as well as planning, monitoring and verification of power application and temperature distribution.

An elliptical phantom with a fat-equivalent ring and lamp matrix was developed for observing the power distribution in ring applicators used for regional hyperthermia. This phantom was used on four European BSD-2000-type therapy systems under routine conditions to test the quality of the SIGMA-60 applicator (systems in Berlin, Essen, Munich and Rotterdam). Frequency-dependent focusing imbalances were observed in all systems. At the time of the quality control test two of the systems displayed considerable errors in their settings. The system setups and possible ways of correcting errors are described in detail. Small maladjustments are caused by coupling effects between antennas and their surroundings and by interactions between the coaxial cables which supply the power. Serious distortions can be caused by phase errors and defects in cables or plugs; the latter can result in significant long-term restrictions on the ability to control the SAR (specific absorption rate) distribution in a way the user may not notice. The measurements gained from these four systems confirm the need for a practical and universal procedure for quality control in regional hyperthermia.

Bericht der Fachstelle Wildtier- und Landschaftsmanagement WILMA für das Amt für Natur, Jagd und Fischerei / Kanton St.Gallen.