Magnetic resonance-guided freehand radiofrequency ablation of malignant liver lesions: a new simplified and time-efficient approach using an interactive open magnetic resonance scan platform and hepatocyte-specific contrast agent.

OBJECTIVES: The aims of this study were to develop magnetic resonance (MR)-guided freehand radiofrequency ablation (RFA) using a near-real-time interactive MR platform in an open 1.0-T MR scanner and to determine the feasibility and safety of this new approach in the clinical setting. METHODS: The study was performed using an open 1.0-T MR system and a low-pass filter to prevent interaction between the RFA generator and the scanner. Artifact size of the radiofrequency needle was measured in 2 perpendicular views (transversal [tra] and coronal [cor]) in vitro and in the tra orientation in vivo for diagnostic (T1 high resolution isotropic volume excitation [THRIVE]/T2 turbo spin-echo [TSE]) and near-real-time (T1 fast-field-echo [FFE]) imaging. A liver-specific contrast medium (gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid) was administered 20 minutes before the intervention to enhance lesion visibility. Visibility was rated and compared for both interventional and diagnostic imaging sequences using a 10-point grading scale. Intervention time and complications were recorded. RESULTS: The mean diameter of needle artifact size for interventional T1 FFE was 17.4 ± 0.7 mm (tra) and 17.1 ± 1.1 mm (cor) in vitro and 15.2 ± 1.5 mm (tra) in vivo. Artifact size for diagnostic imaging was 12.5 ± 1.8 mm (tra) and 11.2 ± 1.4 mm (cor) in vitro and 10.5 ± 1.7 mm in vivo using THRIVE and 8.1 ± 2.4 mm (tra) and 10.8 ± 1.8 mm (cor) in vitro and 9.7 ± 2.0 mm (tra) in vivo using T2 TSE. A total of 57 patients with liver malignancies (mean tumor size, 17 ± 7 mm) underwent freehand MR-guided RFA. In all patients, the ablative procedure was technically successful. Lesion visibility of the diagnostic T2 TSE sequence (4 ± 2) was significantly decreased compared with both the diagnostic (THRIVE, 7 ± 2) and interventional (T1 FFE, 8 ± 1) T1-weighted sequences. Mean time to position the applicator was 7.5 ± 2 minutes. Procedure times ranged from 30 to 60 minutes. The mean in-room time was 57 ± 22 minutes. No major complications were recorded. CONCLUSIONS: Magnetic resonance-guided freehand RFA using a near-real-time interactive MR platform in an open 1.0-T MR scanner is feasible, safe, and applicable in clinical routine. The administration of a hepatocyte-specific contrast agent enhances lesion visualization and therefore improves targeting. Without the need for additional sophisticated devices, this new approach simplifies and shortens the RFA procedure compared with previously published methods.

MR-guided freehand biopsy of liver lesions with fast continuous imaging using a 1.0-T open MRI scanner: experience in 50 patients.

The purpose of this study was to assess a new open system with a field-strength of 1.0 T for the feasibility of liver biopsy using the freehand technique with fast continuous imaging. Fifty patients with focal liver lesions measuring 5 to 30 mm in diameter were included in the study. Guidance and monitoring was performed using a 1.0-T open magnetic resonance (MR) scanner (Panorama HFO; Philips Healthcare, Best, The Netherlands). With fast continuous imaging using a T1-weighted (T1W) gradient echo (GRE) sequence after administration of gadolinium (Gd)-EOB-DTPA, the needle was placed into the lesion. An interface for interactive dynamic viewing in two perpendicular planes prevented needle deviations T2-weighted turbo spin echo (TSE) fat-suppressed sequence was added to rule out postinterventional hematoma or biloma. All lesions were visible on the interventional images. Biopsy was technically successful, and solid specimens were obtained in all cases. Forty-six patients showed a histopathologic pattern other than native liver tissue, thus confirming correct position of the needle. Time between determination of the lesion and performance of the control scan was on average 18 min. No major complications were recorded. MR guidance with the new 1-T open system must be considered an attractive alternative for liver punction. An interface for dynamic imaging of needle guidance and T1W-GRE imaging with administration of Gd-EOB-DTPA for contrast enhancement allows the pinpoint puncture of liver lesions.

Local response and impact on survival after local ablation of liver metastases from colorectal carcinoma by computed tomography-guided high-dose-rate brachytherapy.

PURPOSE: To determine local tumor control after CT-guided brachytherapy at various dose levels and the prognostic impact of extensive cytoreduction in colorectal liver metastases. METHODS AND MATERIALS: Seventy-three patients were treated on a single-center prospective trial that was initially designed to be randomized to three dose levels of 15 Gy, 20 Gy, or 25 Gy per lesion, delivered in a single fraction. However, because there was a high rate of cross-over of subjects from higher to lower dose levels, this study is better understood as a prospective trial with three dose levels. No upper size limit for the metastases was applied. We assessed time to local progression, progression-free survival, and overall survival. RESULTS: According to safety constraints cross-over was performed. The final assignment was n = 98, n = 68, and n = 33 in the 15-Gy, 20-Gy, and 25-Gy groups, respectively. Median diameter of the largest tumor lesion in each patient was 5 cm (range, 1-13.5 cm). Estimated mean local recurrence-free survival for all lesions was 34 months (median not reached). The group assigned to 15 Gy after cross-over displayed 34 local recurrences out of 98 lesions; 20 Gy, 15 out of 68 lesions; 25 Gy, 1 out of 33 lesions. The difference between the 25-Gy and the 20-Gy or 15-Gy group was significant (p < 0.05). Repeated local tumor ablations were the most prominent factor for increased survival and dominated additional systemic antitumor treatments. CONCLUSIONS: Local tumor control after CT-guided brachytherapy of colorectal liver metastases demonstrated a strong dose dependency. The role of extensive minimally invasive tumor ablation in metastatic colorectal cancer needs to be further established.

[Introduction of a MR-compatible system for extracorporal perfusion of vital organs for MR-guided procedures--first-experiences]. / Einsatz eines MR-kompatiblen Organperfusionssystems für physiologische Ex-vivo-Experimente im MRT--Erste Erfahrungen mit einem Tierversuchsersatzsystem.

PURPOSE: To represent a MRI-compatible perfusion-system for extracorporeal perfusion of vital organs which permits the realisation of realistic experiments in a MR scanner. MATERIAL AND METHODS: We performed MR examinations of explanted porcine livers and MR-guided interventions in porcine livers. Explanted organs were hemo-perfused under physiological conditions during the experiments. MR-sequences for diagnostic and interventional examinations were used. RESULTS: The evaluated system was MRI-compatible. The achieved image quality of the used sequences showed excellent anatomical resolution. Planned experiments can be carried out with relatively low expenditure. Diagnostic as well as interventional investigations can be carried out. The used organs showed a stable function within physiological parameters up to 4 hours. CONCLUSION: It is possible to perform ex vivo experiments under in vivo conditions with this system. With the used MR-compatible system MR-guided experimental interventions and thermal ablations can be carried out in explanted organs under in vivo conditions.

Embolization of the gastroduodenal artery before selective internal radiotherapy: a prospectively randomized trial comparing platinum-fibered microcoils with the Amplatzer Vascular Plug II.

The Amplatzer Vascular Plug II (AVP II) is a novel device for transcatheter vessel occlusion, for which only limited comparative data exist. Embolotherapy of the gastroduodenal artery (GDA) is essential before internal radiotherapy (SIRT) in order to prevent radiation-induced peptic ulcerations due to migration of yttrium-90 microspheres. The purpose of this study was to compare the vascular anatomical limitations, procedure time, effectiveness, and safety of embolization of the GDA with coils versus the AVP II. Fifty patients stratified for SIRT were prospectively randomized for embolization of the GDA with either coils or the AVP II. The angle between the aorta and the celiac trunk, diameter of the GDA, fluoroscopy time and total time for embolization, number of embolization devices, complications, and durability of vessel occlusion at follow-up angiography for SIRT were recorded. A t-test was used for statistical analysis. Embolizations with either coils or the AVP II were technically feasible in all but two patients scheduled for embolization of the GDA with the AVP II. In both cases the plug could not be positioned due to the small celiac trunk outlet angles of 17 degrees and 21 degrees. The mean diameter of the GDA was 3.7 mm (range, 2.2-4.8 mm) for both groups. The procedures differed significantly in fluoroscopy time (7.8 min for coils vs. 2.6 min for the AVP II; P < 0.001) and embolization time (23.1 min for coils vs. 8.8 min for the AVP II; P < 0.001). A mean of 6.0 +/- 3.2 coils were used for GDA embolization, while no more than one AVP II was needed for successful vessel occlusion (P < 0.001). One coil migration occurred during coil embolization, whereas no procedural complication was encountered with the use of the AVP II. Vessel reperfusion was noted in only one patient, in whom coil embolization was performed. In conclusion, embolization of the GDA with the AVP II is safe, easy, rapid, and highly effective; only an extremely sharp-angled celiac trunk outlet represented an anatomical limitation for device deployment.

Local arterial infusion of superparamagnetic iron oxide particles in hepatocellular carcinoma: A feasibility and 3.0 T MRI study.

OBJECTIVES: We sought to prove feasibility of selective arterial infusion of superparamagnetic iron oxide (SPIO) particles in patients with hepatocellular carcinoma (HCC). MATERIALS AND METHODS: We studied 13 patients with HCC who underwent modified transarterial chemoembolization (TACE). Six patients received concurrent infusion of Ferucarbotran (Resovist, Schering, Berlin, Germany) in tumor-feeding arteries, and another 6 received MFL AS (MagForce, Nanotechnologies, Berlin, Germany). The iron content of both dispersions was 3.92 mg. One patient served as a control. All patients underwent magnetic resonance imaging (MRI) as baseline and immediate follow-up investigation. RESULTS: Selective arterial infusion of both SPIO particles resulted in significant intratumoral signal intensity decrease on T1-weighted sequences (P < 0.0001), which was greater after MagForce infusion compared with Resovist (P = 0.002). Only minimal amounts of dispersed particles were found in adjacent normal liver parenchyma. No change in intratumoral signal intensity was noted when ferromagnetic particles were omitted. CONCLUSIONS: Modified TACE with selective arterial infusion of SPIO particles can be used for precise tumor targeting in patients with HCC, for which MagForce appeared superior to Resovist.

Osteoid osteoma: experience with laser- and radiofrequency-induced ablation.

The purpose of this study was to analyze the clinical outcome of osteoid osteoma treated by thermal ablation after drill opening. A total of 17 patients and 20 procedures were included. All patients had typical clinical features (age, pain) and a typical radiograph showing a nidus. In 5 cases, additional histological specimens were acquired. After drill opening of the osteoid osteoma nidus, 12 thermal ablations were induced by laser interstitial thermal therapy (LITT) (9F Power-Laser-Set; Somatex, Germany) and 8 ablations by radiofrequency ablation (RFA) (RITA; StarBurst, USA). Initial clinical success with pain relief has been achieved in all patients after the first ablation. Three patients had an osteoid osteoma recurrence after 3, 9, and 10 months and were successfully re-treated by thermal ablation. No major complication and one minor complication (sensible defect) were recorded. Thermal ablation is a safe and minimally invasive therapy option for osteoid osteoma. Although the groups are too small for a comparative analysis, we determined no difference between laser- and radiofrequency-induced ablation in clinical outcome after ablation.

Follow-up of gastro-intestinal stromal tumours (GIST) during treatment with imatinib mesylate by abdominal MRI.

Typical MRI findings for gastro-intestinal stromal tumours (GIST) under treatment with imatinib were evaluated. MRI was performed in 45 patients (25 responders, 20 non-responders) with metastatic or locally advanced, unresectable GIST. Target lesions were selected and re-evaluated after 2, 4, and 6 months of therapy with imatinib. The target tumour response (TTR) was classified according to RECIST criteria. TTR, signal intensity in the centre and border of the lesion and the presence and the extension of a hypervascular rim were analysed. The mean diameter of the marker lesions decreased significantly (P<0.001) from 7.1+/-2.6 cm to 5.9+/-2.3 cm after 6 months. Accuracy of RECIST criteria was 51%, 69% and 73% on MRI 2, 4 and 6 months for response assessment. In addition, responders had higher signal-to-noise ratios on T2-w images after 2 months (P<0.05) and a decrease of vascularised areas in the lesion 4 and 6 months after treatment (each P<0.01), when compared with non-responders. Beyond the size measurement for response assessment, MRI provides additional information of tumour response using SI of T2-w images and quantification of vascularised areas of GIST manifestations.

[Differential diagnosis of intra- and perilienal tumors by use of a RES-specific MRI contrast agent]. / Differenzialdiagnose von Intra- und Perilienalen Tumoren mit Hilfe eines RES-spezifischen MRT-Kontrastmittels.

PURPOSE: To describe the additional benefit in detection and differential diagnosis of peri- and intrasplenic tumors by use of an superparamagnetic iron oxide contrast agent (SPIO). MATERIALS AND METHODS: We represent 7 patients with known malignant tumors. Aim of the examination was the detection and characterisation of intra- or perisplenic tumors. We performed T2w TSE breath triggered sequences before and 10 min after application of SPIO and T1w Flash 2D GRE sequences before and after SPIO and Gadopentetate dimeglumin application. All images were presented to two radiologists, who were asked to asses the presence and characterisation of tumors by using a five-point confidence scale. RESULTS: In two patient intrasplenic hemangiomas were detected, intrasplenic lymphoma, metastasis was excluded, respectively. In two patients perisplenic tumors were diagnosed as gastrointestinal stroma tumors, confirmed by biopsy. In two patients accessory spleens were identified and lymph node metastasis excluded. In one patient an intrasplenic cyst was diagnosed. SPIO enhanced T2w images and Gadopentetate dimeglumin enhanced T1w sequences were evaluated as superior. CONCLUSION: The examination of the spleen by use of superparamagnetic iron oxides offers additional abilities in depiction and charaterisation of intra- and perisplenic tumors in first experiences. First clinical observations indicate that a combination of SPIO enhanced T2w sequences and Gadopentetate dimeglumin enhanced T1w dynamic sequences might be superior to other sequences in detection and characterisation of splenic tumors.

Laser-induced thermotherapy (LITT) of liver metastases: MR-guided percutaneous insertion of an MRI-compatible irrigated microcatheter system using a closed high-field unit.

PURPOSE: To evaluate the efficacy and safety of a new MRI-compatible irrigated laser microcatheter system for thermal ablation of liver metastases. MATERIAL AND METHODS: The new microcatheter system consists of a titanium needle with a diameter of 1.5 mm and a surrounding Teflon catheter with an outer diameter of 1.8 mm (5.5 F). In vitro laser-induced coagulation of bovine liver tissue was performed to determine the optimal perfusion rate of cooling saline flow, maximum laser energy, and ablation time. Laser-induced thermotherapy using the new microcatheter system, an Nd:YAG laser (Dornier), and a flexible laser light guide (Somatex GmbH, Berlin, Germany) was performed in 28 patients with liver metastases. Percutaneous insertion and positioning of multiple microcatheters in the lesion and monitoring of therapy was performed with a closed high-field MRI scanner using T1-weighted gradient-echo sequences during breath-hold. RESULTS: A perfusion rate of 0.75 mL/minute, a laser energy of 15 W, and an ablation time of 20 minutes were found suitable to achieve safe and sufficient ablation of metastatic tissue. The mean volume of induced coagulation in vitro was 23.9 mL. Ablation of liver metastases in patients was technically and clinically successful. CONCLUSION: The new microcatheter system allows for both catheter placement and monitoring of therapy using a single imaging modality. This shortens the procedure and enables more precise puncture and therapy of liver metastases. Due to the miniaturized design of the catheter and the real-time monitoring, the procedure is minimally invasive and very well tolerated by patients. This new technique seems to be a safe and feasible alternative in treating liver metastases.

[Diagnosis of tumors of the small intestine with the aid of CT contrast enema. Sellink CT technique evaluated in 63 patients]. / Diagnostik von Dünndarmtumoren mit Hilfe des CT-Enteroklysma. Die CT--Sellink ausgewertet bei 63 Patienten.

PURPOSE: Aim of the study was to compare the visualisation of small bowel tumours particularly lymphoma of the small bowel by enteroclysma, computed tomography (CT) and computed tomography following enteroclysma. METHODS: We examined 97 examinations in 63 patients. Non Hodgkin's Lymphoma was the primary malignancy in 44 patients, metastasis of different malignancies in 8 patients, primary malignancies of the small intestine in 5 patients, mesenteric tumours in 4 patients and postoperative stricture in another 2 patients. CT following enteroclysma (CT Sellink) was performed as helical CT in 55 patients and as incremental CT in 42 patients. Examinations were evaluated by two radiologists. Evaluation criteria were small bowel distension, perceptibility of details and topographic correlation. RESULTS: Manifestations of lymphoma were found in 32 patients, infiltration of bowel wall in 12 patients. In three patients metastases of melanoma were found. In three patients the suspicion for small bowel tumours was not verified in CT Sellink. The perceptibility of details was evaluated as ameliorated in 45.5% of examinations over all. CONCLUSIONS: CT Sellink offers remarkable advantages in the diagnosis of small bowel tumours compared with enteroclysma and "conventional" computed tomography under intra-venous and oral contrast media. CT Sellink was feasible over a time of 7 years now in clinical praxis. This examination represents an optimized standard in small intestine examination.

[BALTOMA--long-term follow-up]. / BALTOMe--ein Langzeitverlauf.

PURPOSE: The purpose of this work was to describe the findings and the long term follow up of pathologically confirmed bronchus-associated lymphoid tissue lymphoma (BALTOMA) in 6 patients. METHODS: CT examinations and conventional radiological examinations were reviewed and compared to describe typical radiological findings and patterns of pulmonary manifestations. It were described the number of lesions and characteristics like presence of airspace consolidation, ground-glass attenuation, bubble-like radiolucencies, air bronchogram, bronchial dilatation, Infiltration and the long term behaviour of the manifestations. RESULTS: Lesions with a positive air bronchogram, no infiltration of extrapulmonary tissue or extrapulmonary manifestations were revealed as typical findings. Only a slow or no progression of disease was shown in most patients over a term of up to twelve years. CONCLUSIONS: The lymphoma of the bronchus-associated lymphoid tissue of the lung is a rare tumor. A positive air bronchogram, a multiplicity of disease, bilateral lesions, a fibrotic transformation of the lung tissue and no growth or only a slow groth over al long term of observation are typical radiological findings.

Tumour of the diaphragm mimicking liver lesion.

Tumours of the diaphragm bordering the liver may impose diagnostic difficulties. We report the case of a 46-year-old patient diagnosed with a tumour of the liver based on ultrasound and CT. MRI of the liver depicted a tumour growing from the chest wall towards the liver. Surgery revealed the rare entity of a malignant fibrous histiocytoma of the diaphragm.