[Characteristics of necrosis after laser-induced thermotherapy in contrast-enhanced MRI and implications for treatment success]. / Charakteristik von Koagulationsnekrosen nach laserinduzierter Thermotherapie in der kontrastmittelverstärkten Magnetresonanztomografie und deren Einfluss auf den Therapieerfolg.

AIM: This article reports on the use of magnetic resonance imaging to access the post-interventional necrosis volume of liver metastases immediately after and 48 hours after LITT. MATERIAL AND METHODS: In this prospective study, 56 liver metastases from 39 patients (16 females, 23 males, mean age 60.4 years) underwent LITT. The 56 metastases were divided into 4 groups according to the ablation strategy (dependent on multi-applicator technique and laser duration). Groups I and II were treated with an applicator and a time of ablation greater than 15 minutes and 20 minutes, respectively. In groups III and IV the multi-applicator technology with 3 or 4 applicators and a constant ablation time of 20 minutes were used. With the help of heightened contrast MRI of the liver, the portrayal of the post-interventional necrosis was conducted immediately after LITT and 48 hours after LITT. The post-interventional controls after 48 hours were performed during the inpatient stay. The protocol was complemented by an outpatient long-term control after more than 3 months. RESULTS: The local tumor control rate was initially 96.4%. After 3 months it decreased to 92.1%. The mean necrosis volume directly after LITT was: Group I (n = 11; 1 applicator, 30 watt, 10-15 minutes) 6.69 cm(3); Group II (n = 13; 1 applicator, 30 watt, 20 minutes) 10.95 cm(3); Group III (n = 28; 2 applicator, 30 watt, 10-15 minutes) 21.47 cm(3); Group IV (n = 4; 3 applicator, 30 watt, 20 minutes) 40.20 cm(3). In comparison, the necrosis volume after 48 hours increased: Group I 10.56 cm(3); Group II 15.11 cm(3); Group III 31.33 cm(3), Group IV 55.73 cm(3)). CONCLUSION: After 48 hours a progressive increase of post-interventional necrosis volumes compared to volumes directly after LITT was able to be observed. An MRI control after 48 hours, as opposed to an MRI control directly after intervention, is a better indicator for post-interventional success after LITT.

[Technical success rate, peri-interventional complications and radiation exposure of the transarterial embolization for leiomyomas of the uterus]. / Technische Erfolgsrate, peri-interventionelle Komplikationen und Strahlenexposition der transarteriellen Embolisation bei Uterus myomatosus.

PURPOSE: To analyze the technical success rate, incidence and type of peri-interventional complications, and radiation exposure of uterine artery embolization (UAE) in symptomatic leiomyomas of the uterus. MATERIALS AND METHODS: This prospective study includes 75 patients consecutively treated with UAE from October 2000 through August 2002, with all interventions performed by the same radiologist. Technical success rate, interventional material, and incidence and type of peri-interventional complications (length of hospitalization) were recorded and categorized according to the definitions of the Society of Interventional Radiology (SIR). Fluoroscopy time (FT), dose-area product (DAP), and effective dose (ED) were determined for each intervention and the influence of the radiologist's experience on the radiation exposure analyzed. RESULTS: UAE was technically successful in 97.3 % of the cases. Peri-interventional complications occurred in 14.7 %. Four complications (5.3 %) were classified as major class C according to the SIR (post-embolization syndrome requiring prolonged drug treatment and hospitalization [n = 3] perforation of the uterine artery [n = 1]). None of the complications led to discontinuation of the intervention, subsequent surgical intervention, or permanent sequelae. FT decreased significantly (p < 0.05) until the 35th intervention. The median FT decreased from 18.8 min (13.4 - 28 min [25th to 75th percentile]) to 11.8 min (9.7 - 13.3 min [25th to 75th percentile]). The DAP decreased by 25.3 % to a median of 8.547 (6.527 - 11.590 cGy*cm (2) [25th to 75th percentile]). The median ED was 31.5 mSv from the 36th intervention onward. CONCLUSION: UAE has a high technical success rate with a low rate of peri-interventional complications. The study showed a statistically significant learning effect with a decrease in radiation exposure for the first 35 interventions. The effective dose of UAE is comparable to that of 1 to 2 small bowel enema.

[Current concepts and recent developments of laser ablation in tumor therapy]. / Aktueller Stand und Entwicklungen der Laserablation in der Tumortherapie.

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.

Double contrast MRI of thermally ablated liver metastases.

PURPOSE: To investigate the ability of double contrast MRI (enhancement with iron oxide and gadopentetate dimeglumine) to increase the difference in contrast between various tissues after thermal ablation of liver metastases. MATERIALS AND METHODS: 12 patients were imaged after MR-guided laser-induced thermotherapy (LITT). Imaging was performed with a 1.5T MR system. Nonenhanced, iron oxide-enhanced and double contrast images were acquired using T (1)-weighted GRE and T (2)-weighted TSE sequences. Iron oxide imaging was performed 10 min after injection of 1.4 ml ferucarbotran (Resovist(R), Schering AG Berlin, Germany) and double contrast imaging 60 sec after the additional injection of 0.1 mmol/kg body weight gadopentetate dimeglumine (Magnevist(R), Schering AG Berlin, Germany). Qualitative and quantitative assessment was performed on induced necroses, residual or recurrent tumor tissue and metastatic tissue untreated at the time of the study. RESULTS: Iron oxide-enhanced T (1) GRE images demonstrated the highest contrast between ablated hyperintense tissue and iron accumulating and resultant hypointense liver parenchyma. Due to Gd enhancement, double contrast T (1)-weighted GRE images displayed the highest change in signal intensity in vital tumor tissue compared to ablated tissue and iron oxide accumulating liver parenchyma (p < 0.01). CONCLUSIONS: First observations indicate that LITT of hepatic metastases can be better followed with double contrast MRI, which displays increased contrast due to Gd enhancement of perfused tumor tissue and signal intensity loss in iron oxide accumulating hepatic parenchyma. Induced necrosis does not change its signal intensity at all after injection of iron oxide and Gd-containing contrast media.

[Laser-induced thermotherapy (LITT) of lung metastases: description of a miniaturized applicator, optimization, and initial treatment of patients]. / Laser-induzierte Thermotherapie (LITT) von Lungenmetastasen: Beschreibung eines miniaturisierten Applikators, Optimierung und erste Patientenbehandlungen.

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.

[Laser-induced thermotherapy (LITT) for malignant liver tumours: the role of sonography in catheter placement and observation of the therapeutic procedure]. / Laser-induzierte Thermotherapie (LITT) bei malignen Lebertumoren: Einsatz der Sonographie zur Katheterplatzierung und Prozessbeobachtung.

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.

Histopathological correlation to MRI findings during and after laser-induced thermotherapy in a pig pancreas model.

RATIONALE AND OBJECTIVES: To investigate whether percutaneous laser-induced thermotherapy (LITT) with continuous magnetic resonance (MR) monitoring of thermal effects within the pancreas is feasible in a porcine model. METHODS: Laser applicators were placed in the pancreas of 15 female pigs. A temperature-sensitive (thermo--fast low-angle shot) sequence was used for continuous monitoring of thermal effects during LITT at 1.5 T. Follow-up MR images were acquired, the pigs were observed for 7 days, and then a pathological examination was performed after sacrifice. RESULTS: Continuous MR monitoring visualized thermal effects in pancreatic tissue and thermal damage of the spleen (n = 1), the left kidney (n = 1), and peripancreatic fat (n = 4) but missed the thermal damage of the duodenum (n = 2). Thermal-induced lesions (10--32-mm diameter) were clearly visualized on contrast-enhanced T1-weighted images. CONCLUSIONS: Laser-induced thermotherapy of pancreatic tissue was feasible in this porcine model, and online monitoring was practicable. Further studies are necessary to increase the accuracy of online MR imaging of thermal effects.

[Laser-induced thermotherapy (LITT). Use of round and pointed laser applicator systems--initial results]. / Laserinduzierte interstitielle Thermotherapie (LITT). Anwendung runder und spitzer Laserapplikatorsysteme--erste Ergebnisse.

PURPOSE: To assess the advantages and disadvantages by using round and sharp laser application systems during laser-induced thermotherapy. METHOD: 6 in vitro examinations were performed and 12 patients with liver metastases of colorectal carcinoma were treated with laser-induced thermotherapy. All lesions were closely localised to the diaphragm, liver capsule and large intrahepatic vessels. Five patients were treated with the sharp and 7 patients with the round applicator system. After CT-guided insertion of the catheter system into the metastasis laser therapy was performed under MRI control (approx. 25 W, 20 min). RESULTS: Reduction of the distance between the laser applicator and rounded laser catheter tipp (approx. 0.5-1 cm) leads to better placement of the laser applicator in metastases located near the diaphragm, liver capsule and large intrahepatic vessels. Improved therapy results due to complete ablation of metastases were obtained. All patients treated with the round system had complete ablation of metastasis. In 3 of 5 patients treated with the sharp system, MRI control 2 days after therapy showed a residual tumour margin close to the diaphragm or to an intrahepatic vessel. DISCUSSION: Improved ablation can be obtained by closer placement of a round laser catheter in liver metastasis located near the diaphragm, liver capsule and large intrahepatic vessels.

[Fusion of CT and PET data: methods and clinical relevance for planning laser-induced thermotherapy of liver metastases]. / Fusion von CT- und PET-Daten: Methode und klinische Bedeutung am Beispiel der Planung der laserinduzierten Thermotherapie von Lebermetastasen.

AIM: Catheter-placement in liver metastases is difficult when the lesions are not visible on plain images. We evaluated the use of image fusion using CT and PET data, providing information on anatomy and liver lesions, respectively. METHODS: Plain CT of the liver and whole body FDG-PET were performed in 28 patients with colorectal carcinoma in preparation for laser-induced thermotherapy. Fusions of image data and 2D-visualisation were performed and evaluated with regard to quality of the registration, number of detected lesions and influence of the procedure on laser-induced thermotherapy. Image fusion was performed using an algorithm which was developed by our group. RESULTS: 84 focal liver lesions were visible on CT, 107 on PET images. This means that CT guided catheter placement would have to be performed "blindly" in 23 lesions. In 6 patients previously unknown extra-hepatic tumor deposits were seen on PET images (local recurrence, 2 extrahepatic metastases, 2 second primaries). CONCLUSION: Hot spots from metastases, which are difficult to locate on PET images alone, may be identified on images generated by fusion of CT and PET data. These images facilitate an interventional approach to liver lesions which are not visible on plain CT. As PET allows for whole body screening, it helps identifying patients who would not profit from laser-induced thermotherapy.

Selenium levels of beef cattle in southeastern british columbia relative to supplementation and type of pasture.

Moderate to extremely low levels of selenium in hay were related to marginally deficient levels of selenium in sera from cattle in the Windermere Valley of southeastern British Columbia. Deficiency was most pronounced in cattle fed local hay during the winter or grazed on fertilized/irrigated pastures. Cattle on range had adequate levels of serum selenium. When sodium selenite was fed at 1.0 and 3.5 mg per head per day, serum selenium levels increased commensurate with the dose. Clinical observations indicated that a variety of clinical problems disappeared after injection or supplementation with selenium/vitamin E.