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 (p < 0.001). 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.
Reversible bilateral lesions of the claustrum and external capsule in a 12-year-old girl suffering from a severe, transitory encephalopathy are reported. After a prodromal stage of feeling uncomfortable a sudden onset of status epilepticus occurred, followed by recurrent complex partial and myoclonic seizures for 3 weeks, with psychotic symptoms and temporary loss of vision, speech and hearing. After treatment with phenytoin the patient became free of seizures and recovered completely without neurological deficit. The initial cranial CT was normal; however, cranial MRI 7 days later showed bilateral selective lesions of the claustrum and external capsule, which disappeared completely 5 weeks later. The aetiology of these lesions remains obscure; repeated cerebrospinal fluid and blood tests were negative for herpes simplex virus and other infectious agents. The clinical and radiological improvement were concomitant. This may indicate a functional disturbance of the claustrum grey matter, rather than lesions of the white matter of the external and extreme capsules.
Purpose:To evaluate the influence of parallel imaging on the image quality of respiratory triggered magnetic resonance cholangiopancreatography (MRCP). Materials and Methods:A total of 30 consecutive patients underwent MRCP applying a respiratory triggered T2-weighted (T2w) turbo spin-echo (TSE) sequence without and with parallel imaging (acceleration factor of 2). Acquisition times of both sequences were recorded. Quantitative evaluation included measurement of a contour sharpness index of two segments of the pancreaticobiliary tree as well as calculation of the relative contrast between ductal structures and organ parenchyma at four different segments. The qualitative evaluation was performed by two independent radiologists who graded overall image quality, depiction of eight segments of the pancreaticobiliary tree, and the frequency of artifacts. Results:The application of parallel imaging significantly (P Ͻ 0.05) reduced the acquisition time of the respiratory triggered MRCP sequence by 37.7% (six minutes and two seconds Ϯ one minute and 26 seconds vs. three minutes and 46 seconds Ϯ 58 seconds). The quantitative and qualitative evaluation revealed no statistically significant differences between the two sequences (P Ͼ 0.05). The frequency of artifacts was at the same level for both sequences as well. Conclusion:The application of parallel imaging for respiratory triggered MRCP significantly reduces the acquisition time without relevant influence on image quality. MAGNETIC RESONANCE IMAGING is more time-consuming compared to other imaging modalities, in particular multi-slice computed tomography. A major challenge in the future development of health systems is the increase of economic efficiency. For diagnostic imaging including MRI the reduction of acquisition time is one of the central tools for cost-decreasing.Magnetic resonance cholangiopancreatography (MRCP) is a noninvasive MR procedure that provides detailed information on anatomy and pathology of the pancreaticobiliary ductal structures using heavily T2-weighted (T2w) sequences with long echo-times (1,2). Various MRCP techniques have been introduced that differ in spatial resolution and acquisition time (3,4). Recent studies propose that high resolution turbo-spin echo (TSE) sequences with respiratory triggering are superior to breath-hold sequences (5-7). However, respiratory triggered sequences have distinctively longer acquisition times in comparison to breathhold imaging potentially limiting the acceptance in daily practice.Parallel acquisition techniques are a time saving method that require certain hard-and software installations, in particular dedicated multi-channel receiver coils (8 -10). The integrated parallel acquisition technique (iPAT), which is the technical basis for this investigation, can be applied to respiratory triggered MRCP using multi-channel surface coils and the generalized autocalibrating partially parallel acquisition (GRAPPA) algorithm for image reconstruction (11). With this approach the acquisition time can be reduced, a...
Thirty-nine patients with Graves ophthalmopathy were examined with magnetic resonance (MR) imaging at 0.5 T with use of a surface coil. T1- and T2-weighted spin-echo images were obtained, and T2 relaxation times of eye muscles and retrobulbar fat were calculated from a multiecho sequence. Normal values for T2 relaxation times of eye muscle were obtained by examining nine control subjects. MR imaging demonstrated eye muscle enlargement in 23 patients. Visual examination of T2-weighted and calculated T2 images showed areas of high signal intensity in enlarged eye muscles of 12 of 23 patients. Calculated T2 relaxation times of eye muscles differed significantly between control subjects and patients with stage III and IV disease. Signal intensity characteristics of these changes, as well as their correlation with well-known histologic findings, suggested their interpretation as edema caused by acute inflammation. Since computed tomography is not able to depict eye muscle edema, the MR findings of structural changes within enlarged eye muscles might have an impact on therapeutic decisions concerning the application of anti-inflammatory drugs.
For the differentiation of primary brain tumours the single dose was sufficient, in metastatic lesions triple dose was essential for the detection or exclusion of multifocality.
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