PubMed Health⌕ Search

Biomedical subjects

N Hosten

Publications and source records attributed to N Hosten.

At least 19 recordsLinked to original sources
PubMed2005

Intestinal fluid volumes and transit of dosage forms as assessed by magnetic resonance imaging.

AIM: The gastrointestinal transit of sequentially administered capsules was investigated in relation to the availability of fluid along the intestinal lumen by magnetic resonance imaging. METHODS: Water-sensitive magnetic resonance imaging was performed on 12 healthy subjects during fasting and 1 h after a meal. Specifiable non-disintegrating capsules were administered at 7, 4 and 1 h prior to imaging. RESULTS: While food intake reduced the mean fluid volumes in the small intestine (105 +/- 72 mL vs. 54 +/- 41 mL, P < 0.01) it had no significant effect on the mean fluid volumes in the colon (13 +/- 12 mL vs. 18 +/- 26 mL). The mean number of separated fluid pockets increased in both organs after meal (small intestine: 4 vs. 6, P < 0.05; large intestine: 4 vs. 6, P < 0.05). The distribution of capsules between the small and large intestine was strongly influenced by food (colon: 3 vs. 17 capsules, P < 0.01). CONCLUSIONS: The results show that fluid is not homogeneously distributed along the gut, which likely contributes to the individual variability of drug absorption. Furthermore, transport of fluid and solids through the ileocaecal valve is obviously initiated by a meal-induced gastro-ileocaecal reflex.

Adult↗
PubMed2005

[No detectable nephrotoxic side effect using a dimer, non-ionic contrast media in cerebral perfusion computed tomography in case of suspected brain ischemia].

PURPOSE: In suspected brain ischemia, the perfusion cerebral computed tomography (cCT) should be performed with the lowest amount of contrast media to avoid a contrast media induced nephropathy (CIN) even if the patient already is in renal failure. We were interested to find the best parameters for this examination. MATERIAL AND METHODS: From February 2000 to March 2003, 138 patients (58 females, 80 males, mean age 66.8 years) underwent cCT-perfusion immediately after the admission to our stroke unit. Of these patients, 62% (n = 86) had normal renal function and 38% (n = 52) renal failure (up to 381 micromol/l basic serum creatinine). We varied volume (20-80 ml), flow (5 vs. 7.2 ml/s) and concentration (270 vs. 320 ml/mg iodine) of a dimer, non-ionic contrast media (Visipaque) to establish 5 groups. So we got patients receiving 6 g, 12 g, 16 g, 19 g and 25 g of iodine. After generating the perfusion maps, two radiologists reviewed the quality of the maps and scored it (1-5). We measured the serum creatinine before contrast application and at follow up cCT (days 3 and 7). RESULTS: The quality of the maps increases with increasing amount of iodine. However, the diagnostic result was not significantly better using more than about 16 g of iodine (e. g., 60 ml--7.2 ml/s--270 mg/ml) in cCT-perfusion studies. Only one patient had a pathologic increase in serum creatinine (day 1: 93; day 4: 146 micromol/l) but died at day 5 because of massive co-morbidity and septic pneumonia. No CIN occurred even in the patient group with pre-existent renal failure. CONCLUSIONS: About 60 ml contrast media and a moderate flow rate of about 7 ml/s ensure good results in perfusion-cCT, even if the patients have poor blood circulation or arteriosclerosis. The use of a dimer, non-ionic contrast media (range of 6-25 g iodine) seems to minimize the risk of CIN in the daily routine.

Aged↗
PubMed2005

[Laser-induced thermotherapy (LITT) of tumors of the liver in central location: results and complications].

PURPOSE: To investigate whether laser-induced thermotherapy (LITT) for tumors of the liver in central location is a sufficient and safe therapeutic option. MATERIAL AND METHODS: According to predefined criteria, 23 of 136 patients were chosen to be treated with LITT because of malignant liver tumors. At the time of the first LITT, the patients had 28 central tumors (27 metastases, one HCC), which were treated in 34 sessions with 64 laser applications and had a clinical and imaging follow-up every 3 months. RESULTS: The primary effectiveness rate was 74.1% and the secondary effectiveness rate 82.1%. The mortality rate was 0%. Major complications occurred in one patient (hemorrhagic pleural effusion), while minor complications occurred in 10 patients. During the median follow-up of 20 months (range 3-57 months), local tumor progression developed in 22% of the tumors. The effectiveness rate was 78.6%, 71.4% and 64.3% after 3, 6 and 9 months. The median survival was 46.0 months (95% confidence interval: 28.6-47.1 months). CONCLUSION: In our patients, complications and ablation rate of laser-induced thermotherapy for central liver tumors do not differ from those in peripheral location as described in the literature.

Confidence Intervals↗
PubMed2004

[Current concepts and recent developments of laser ablation in tumor therapy].

PURPOSE: The purpose of this paper is to present technical innovations and clinical results of percutaneous interventional laser ablation of tumors using new techniques. METHODS; Laser ablation was performed in 182 patients (liver tumors: 131, non hepatic tumors-bone, lung, others: 51) after interdisciplinary consensus was obtained. The procedure was done using a combination of imaging modalities (CT/MRI, CT/US) or only closed high field MRI (1.5 T). All patients received an MRI-scan immediately after laser ablation. RESULTS: In 90.9% of the patients with liver tumors, a complete ablation was achieved. Major events occurred in 5.4%. The technical success rate of laser ablation in non-hepatic tumors was high, clinical results differed depending on the treated organ. CONCLUSIONS: The treatment of tumors of the liver and other organs up to 5 cm by laser ablation was a safe procedure with a low rate of complications and side effects. Image guidance by MRI is advantageous for precise tumor visualization in all dimensions, therapy monitoring, and control of laser ablation results.

Adult↗
PubMed2004

[Percutaneous thermoablation of lung metastases. Indication, performance, initial results, and imaging findings].

Not unlike thermoablation of liver metastases, thermoablation of metastases to the lungs is gaining clinical interest. Radiofrequency ablation and laser-induced interstitial thermotherapy are both used clinically. Initially it was suspected that percutaneous treatment of lung metastases would result in a rate of pneumothoraces and tissue reactions which would not be clinically acceptable. However, this did not prove true. Fear of pneumothoraces however did lead to the desire for an applicator with a maximally reduced diameter. While clinical results are not yet available, technical success rates of laser-induced interstitial thermotherapy of lung metastases are promising. The percentage of pneumothoraces does not differ significantly from that seen in diagnostic procedures. Large metastases may be treated by simultaneous use of multiple applicators or by repositioning of an applicator (pullback technique). Surgical experience is still guiding us in deciding which primaries' metastases may be successfully treated percutaneously. The literature indicates that lung metastases from colorectal primaries are especially suited. Radiotherapy is only an alternative method in cases of lung metastases if they cause symptoms (such as pain because of thorax infiltration or difficulty in breathing because of bronchial lesion). Due to the risk of radiation-induced pneumonia general radiotherapy is not to be recommended. The possibility of stereotactic ray treatment is being considered, but because breathing shifts the metastases it is not yet feasible. Therefore, percutaneous thermoablation could be used as a minimally invasive, rather riskless therapeutic option for a relatively high percentage of inoperable lung metastases.

Catheter Ablation↗
PubMed2004

[Percutaneous ablation of pulmonary tumours: state-of-the-art 2004].

Percutaneous radiofrequency ablation (RFA) and laser-induced interstitial thermotherapy (LITT) are well established since many years in liver and other soft tissue tumors. During the past 2 years there are increasing reports on applications in pulmonary tumors. There are, however, numerous differences to ablations in other organs: indications in pulmonary metastases and lung cancer have to be balanced against the specific possibilities of well-established surgical resections. Tissue specific features require different concepts of energy deployment and complications and methods for assessment of therapeutic effectiveness vary from other applications. Other aspects, however, are quite clear, yet. There are specific established indications particularly for thermoablation of pulmonary metastases. Tumor ablation is easily performed by experienced interventional radiologists and serious complications are rare. Patient acceptance is good. Further studies are required on indications, technical requirements, therapy control and particularly long-term results.

Carcinoma, Bronchogenic↗
PubMed2004

[Percutaneous laser-induced thermotherapy of lung metastases: experience gained during 4 years].

We perform laser ablation of lung metastases for four years. In the following we report on technical success, ablation results and follow-up. 30 patients with a total of 42 lung metastases were treated. Patients were aged between 42 and 74 years. Primary tumors were mostly colorectal carcinomas, head and neck and uro-genital tumors. Technical success was achieved in 40, complete ablation in 14 metastases (33%); however, in 8 metastases follow-up was too short for a valid evaluation (4-8 weeks). Further analysis may improve the overall results: metastases located in the central parts of the lungs were more easily treated than those located peripherally, best results were achieved in metastases not larger than 3 cm, percutaneous ablation of lung metastases has potential as an additional therapeutic option if surgery is not possible.

Adult↗
PubMed2004

[Differential diagnosis of intraconal orbital masses using high-resolution MRI with surface coils in 78 patients].

PURPOSE: Over the last decade, MRI has become the standard procedure for the diagnosis of orbital masses. Purpose of the study was to evaluate criteria for differential diagnosis for intraconal masses on MRI in a large patient group. MATERIAL AND METHODS: In a retrospective study, MR examinations of 78 patients with intraconal masses were evaluated. All examinations were performed using surface coils for high spatial resolution. Signal behavior on T2-WI and T1-WI before and after contrast application as well as further tumor characteristics (i. e., shape, size, position, delineation and infiltration) were evaluated. Every diagnosis was proven by histopathological results from extirpation (n = 18) or biopsy (n = 22), or confirmed by other imaging modalities (n = 13) or clinical course (n = 25). RESULTS: Different tumor characteristics are helpful in the differentiation between cavernous hemangioma, lymphangioma, varices, AV malformations and solid tumors. Due to overlapping in the imaging appearance, the differentiation between inflammatory pseudotumor, lymphoma and orbital metastasis was more difficult. CONCLUSION: While high resolution MRI using surface coils allows differentiation between the typical vascular tumors, the differentiation between solid tumors is more difficult. Thus, a histopathologic verification of the diagnosis is necessary in solid tumors.

Adolescent↗
PubMed2004

[Clinical use of digital retrospective image fusion of CT, MRI, FDG-PET and SPECT -- fields of indications and results].

PURPOSE: To evaluate the feasibility and the clinical benefits of retrospective digital image fusion (PET, SPECT, CT and MRI). MATERIALS AND METHODS: In a prospective study, a total of 273 image fusions were performed and evaluated. The underlying image acquisitions (CT, MRI, SPECT and PET) were performed in a way appropriate for the respective clinical question and anatomical region. Image fusion was executed with a software program developed during this study. The results of the image fusion procedure were evaluated in terms of technical feasibility, clinical objective, and therapeutic impact. RESULTS: The most frequent combinations of modalities were CT/PET (n = 156) and MRI/PET (n = 59), followed by MRI/SPECT (n = 28), CT/SPECT (n = 22) and CT/MRI (n = 8). The clinical questions included following regions (more than one region per case possible): neurocranium (n = 42), neck (n = 13), lung and mediastinum (n = 24), abdomen (n = 181), and pelvis (n = 65). In 92.6 % of all cases (n = 253), image fusion was technically successful. Image fusion was able to improve sensitivity and specificity of the single modality, or to add important diagnostic information. Image fusion was problematic in cases of different body positions between the two imaging modalities or different positions of mobile organs. In 37.9 % of the cases, image fusion added clinically relevant information compared to the single modality. CONCLUSION: For clinical questions concerning liver, pancreas, rectum, neck, or neurocranium, image fusion is a reliable method suitable for routine clinical application. Organ motion still limits its feasibility and routine use in other areas (e. g., thorax).

Adolescent↗
PubMed2003

[Laser-induced thermotherapy (LITT) of lung metastases: description of a miniaturized applicator, optimization, and initial treatment of patients].

PURPOSE: A thin-caliber applicator system was developed for introducing a laser fiber under CT guidance into lung metastases with only minimal complications. MATERIALS AND METHODS: A space-saving 5.5 French Teflon cannula with a titanium trocar and connectors for a laser light guide (2 or 3 cm Dornier Diffusor-Tip H-6111-T2 or H-6111-T3 coupled to a Dornier Medilas Fibertom 5100 laser, wavelength of 1064 nm) and a perfusion line for physiologic saline solution were developed. After puncture the laser Diffusor-Tip remains in the cannula and is cooled during its tissue passage by slowly flowing saline solution. The miniaturized applicator system (Monocath) was calibrated in nonperfused bovine liver for maximum energy supply and necessary flow of the cooling saline solution in reference to a commercially available 9 French laser catheter with an 11.5 French inducer sheath (Power-Applicator). The new applicator system was used for treating lung metastases in 10 patients over a period of 21 months. RESULTS: The size of heat coagulation in bovine liver was 24 +/- 2 ml using the miniaturized system with application of 15 W for 20 min and a saline flow of 0.75 ml/min, in comparison to a size of 29 +/- 7 ml for the commercial applicator (30 W, 20 min, 60 ml/min). All metastases could be safely approached with the miniaturized applicator, except for two metastatic lesions at the lung base in two patients. A minor pneumothorax developed in three patients and intrapulmonary bleeding in two. Contrast-enhanced CT demonstrated necrosis of the treated metastatic areas in 6 patients. Follow-up of three patients after 5, 6, and 8 months showed complete tumor regression with minimal scarring in one patient. CONCLUSION: The miniaturized applicator system enables the introduction of a laser fiber into pulmonary metastases with only minor complications. Complete ablation seems to be achievable in suitable patients with the applied laser energy and a slow cooling fluid flow rate.

Adult↗
PubMed2003

[MR-based volumetric analysis of small tumor volumes: accuracy of phantom examinations of simulated eye tumors].

PURPOSE: The determination of tumor volume in ocular tumors is very important for the planning and success of radiation therapy. This study uses an animal model to evaluate the accuracy of MR-based volumetry of ocular tumors. MATERIALS AND METHODS: In a total of 25 porcine eyes obtained from the slaughterhouse, ocular tumors were produced by injecting a mixture of hand creme and Gd-DTPA under ophthalmoscopic guidance. The injected volume varied between 0.05 ml and 2.7 ml. The eyes were examined with a 1.5 Tesla scanner and a 4 cm circular surface coil especially developed for ocular MRI. After data transfer to a separate workstation, volumetric analysis was carried out by three independent radiologists using semiautomated software. The determined volume was compared with the injected volume. RESULTS: Of the 25 prepared porcine eyes, 23 were suitable for volumetric analysis. The injection of the mixture of hand creme and Gd-DTPA produced two different types of tumors. Ophthalmoscopically, 14 ellipsoid and 9 lobulated to mushroom-shaped tumors were found and confirmed by MRI. Minor deviation was found between injected volume and volume calculated by MRI, with a correlation coefficient of 0.96. CONCLUSION: Using appropriate technique, MRI is capable of determining small tumor volumes with high accuracy in an animal model. Minor differences can be expected when transferring the results to clinical studies.

Animals↗
PubMed2003

High resolution magnetic resonance imaging of retinoblastoma.

BACKGROUND/AIMS: Diagnosis of retinoblastoma is mainly based on indirect ophthalmoscopy, but additional imaging techniques are indispensable for the staging of the disease. A new high resolution magnetic resonance imaging (MRI) technique for the examination of the eye was evaluated. A new surface coil with a diameter of 5 cm allows a field of view of 60 mm with an in-plane resolution of 0.8 mm. We compared preoperative MRI scans with the histology after enucleation in 21 cases of retinoblastoma. Parameters studied were appearance of retinoblastoma, choroidal and scleral infiltration, extraocular extension, optic nerve infiltration, and vitreous seeding. RESULTS: All retinoblastomas could be visualised as hypointense to vitreous on T2 weighted images and slightly hyperintense to vitreous on plain T1 weighted images with a moderate enhancement after contrast application. Histology revealed seven cases with infiltration of the optic disc or optic nerve. Preoperative MRI scans depict juxtapapillary tumour masses, but it was impossible to differentiate between a juxtapapillary retinoblastoma, a prelaminar infiltration of the optic disc, or a just postlaminar optic nerve infiltration. In five of 14 cases with a proved tumour infiltration of the choroid, MRI scans showed an inhomogeneous contrast enhancement of the choroid in enhanced T1 weighted sequences beneath the retinoblastoma. Whether this sign is specific for a choroidal infiltration or is just an artefact remains unclear. High resolution MRI scans did not allow the exclusion of this form of intraocular tumour extension. All nine cases with proved vitreous seeding were not detected by MRI scans. None of these cases showed scleral infiltration or orbital tumour extension. Therefore, it is not possible to judge the rank of this technique in detecting orbital tumour growth. CONCLUSION: The new MRI technique is of limited value in visualisation of prelaminar or postlaminar infiltration of the optic nerve. Advanced choroidal infiltration might be visualised by contrast enhanced T1 weighted MRI scans, but the available spatial resolution did not allow the exclusion this critical form of tumour growth by MRI scans. Nevertheless, high resolution MRI with the new surface coil has superior contrast and spatial resolution compared to computed tomograph (CT) or other available imaging techniques. MRI cannot replace CT in detecting tumour calcification but with increasing experience with this new technique it should be possible to renounce CT scans in the majority of cases of retinoblastoma.

Child↗
PubMed2002

Intraperitoneal distribution of ultrasound contrast medium imaged with B-mode ultrasound and colour-stimulated acoustic emission imaging.

Intraperitoneal port catheter systems for local delivery of cytotoxic drugs require imaging prior to chemotherapy to confirm homogenous distribution of an injected fluid in the entire peritoneal cavity. This study was performed to assess whether contrast-enhanced ultrasound (US) is a suitable imaging modality for this task. Twelve patients with peritoneal carcinosis and an implanted intraperitoneal port catheter system were studied before chemotherapy. Ultrasound examinations were performed after bolus injections of the microbubble contrast medium Levovist. Distribution of the contrast medium in the peritoneal cavity was imaged using B-mode US and colour-stimulated acoustic emission imaging (SAE). Contrast-enhanced CT imaging was used as term of reference for evaluating the US results. Distribution of the microbubbles in the peritoneal cavity was easily detected by both US methods. In 10 of 12 patients a free distribution in all abdominal quadrants was seen with both US techniques. In 2 of 12 patients, CT and US showed contrast medium limited to the perihepatic area. Therapy was stopped and surgical repositioning of the catheter was performed. Ultrasound after intraperitoneal injection of a microbubble contrast agent provides reliable information about the distribution of intraperitoneally injected fluid in the peritoneal cavity. This method is therefore well suited for imaging port catheter systems prior to chemotherapy.

Acoustics↗
PubMed2002

[Laser-induced thermotherapy (LITT) for malignant liver tumours: the role of sonography in catheter placement and observation of the therapeutic procedure].

AIM: Evaluation of sonography in the placement of catheters for laser-induced thermotherapy (LITT) as well as for the observation of the therapeutic procedure in cases of malignant liver tumours. METHODS: Following the placement of 1-4 LITT applicators, 18 patients with malignant liver tumours (recurrence of hepatocellular carcinoma n = 5, metachronous liver metastases n = 13) were examined by ultrasound to determine the position of the applicators as well as the sonographic visualisation of the respective lesion. The laser treatment procedure was also observed sonographically. As standard reference method for the documentation of thermally induced necroses we used magnetic resonance tomography 24-48 hours after the procedure. RESULTS: The tip of the applicator could be localised in all cases, and the position of the applicator relative to the lesion could be directly visualised in 78% of cases. The hyperechogenic thermal effect during LITT had a median size of 4.5 cm, thus proving to be significantly larger than the actual necrosis induced (p < 0.01). The sonographic observation of the procedure identified 8/10 primarily incomplete ablations which were then treated again immediately after correction of the position of the applicators. CONCLUSION: Continuous sonographic observation of the procedure of LITT can yield important additional information.

Adult↗
PubMed2001

Contrast-enhanced color Doppler sonography of uveal melanomas.

PURPOSE: The purpose of our study was to evaluate the use of the galactose microbubble-based contrast agent Levovist in color Doppler sonography of uveal melanomas. We also evaluated the use of the resistance index and pulsatility index in differentiating tumor-associated vessels from normal vessels in patients with uveal melanomas. METHODS: In this prospective study, 40 patients with uveal melanoma were examined with color Doppler sonography before and after the administration of the contrast agent Levovist. The Doppler signals were recorded from both the tumor and the orbit and were evaluated quantitatively and qualitatively. RESULTS: Tumor-associated vessels were detected without contrast enhancement in 36 of 40 patients and with contrast enhancement in 38 of 40 patients. The spectral characteristics of the Doppler signals did not change after the injection of Levovist. There were no differences-qualitative or quantitative-in Doppler signals between normal and tumor-associated vessels. CONCLUSIONS: The injection of Levovist slightly improved the detection of small vessels in uveal melanomas and the orbit but did not help to differentiate between normal vessels and tumoral vessels. The differentiation of a solid tumor from subretinal hemorrhage or effusion was improved.

Adult↗