P. L. Pereira

Freehand Real-Time MRI-Guided Lumbar Spinal Injection Procedures at 1.5 T: Feasibility, Accuracy, and Safety

OBJECTIVE The purpose of this study was to test the hypothesis that freehand real-time MRI-guided lumbar spinal injection procedures are feasible, accurate, and safe when performed with a clinical open-bore 1.5-T MRI system. MATERIALS AND METHODS A retrospective analysis was made of spinal injection procedures performed over an 18-month period. Forty-nine procedures were performed on 37 patients (23 women, 14 men; mean age, 36 years; range, 18-48 years). A rapid FLASH 2D MRI sequence (TR/TE, 9.3/3.5; slice thickness, 5 mm; acquisition time, 1 second) was used for real-time needle placement with freehand technique. Data assessed were type of procedure, qualitative and quantitative image quality, dimensions of needle artifact, rate of successful drug delivery, rate of vascular uptake, time requirements, and occurrence of complications. RESULTS Among the 49 procedures, 22 (45%) were nerve root injections, 18 (37%) were facet joint injections, and nine (18%) were epidural injections. The quality of real-time FLASH 2D MR images was sufficient in all cases. Contrast-to-noise ratios were sufficiently high for good delineation of relevant structures. The needle artifact made was remarkably constant with an average overestimation of length of 1.0 +/- 0.2 [SD] mm. Drug delivery was successful in all selective nerve root injections and epidural injections. The rate of successful drug delivery was 89% (16 of 18) for facet joint injections. No complete intravascular injections occurred. The mean table time was 36 minutes (range, 23-75 minutes). The mean real-time MRI time was 38 seconds (range, 12-185 seconds). No major complications occurred. CONCLUSION We accept the hypothesis that freehand real-time MRI-guided lumbar spinal injection procedures are feasible, accurate, and safe when performed with a clinical open-bore 1.5-T MRI system. We note that real-time MRI guidance has the additional advantage of a complete absence of patient and operator exposure to ionizing radiation.

Transarterial chemoembolization of liver metastases in patients with uveal melanoma

Metastases from uveal melanoma are often confined to the liver. Palliative hepatic chemoembolization has been considered to be a reasonable treatment approach. We enrolled 14 patients with hepatic metastases from uveal melanoma into a pilot trial of transarterial chemoembolization (TACE). All patients received additional systemic immuno-chemotherapy or best supportive care. In 31 procedures 100mg/m(2) of cisplatine was continuously infused by means of a power injector preceding embolization by manual injection of polyvinyl alcohol particles. In three procedures cisplatine was replaced by 200mg/m(2) carboplatine because of increased serum creatinine levels. Tumor response was evaluated using RECIST criteria. Fourteen patients received 34 TACEs (mean: 2.4 treatments). Eight patients (57%) achieved partial response (PR), four patients (29%) had stable disease and two patients (14%) tumor progression. Median time to progression was 8.5 months (5-35 months). Median survival after first TACE was 14.5 months in responders compared to 10 months in non-responders (p=0.18, not significant) and 11.5 months (3-69 months) in all patients. In seven patients with metastases occupying less than 25% of liver volume median survival was 17 months compared to 11 months in seven patients with tumor involvement of more than 25% (p=0.02) with partial response rate of 86% and 29%, respectively. TACE of liver metastases from uveal melanoma is well tolerated and may prolong survival in patients with limited tumor extension.

Real-time MR fluoroscopy-navigated lumbar facet joint injections: feasibility and technical properties.

We prospectively evaluated the feasibility and technical properties of a dedicated interventional magnetic resonance (MR) imaging protocol for near-real-time MR fluoroscopy-guided bilateral lumbar facet joint injections. A total of 44 facet joint injections were performed in 22 patients using a C-shaped open 0.2-T MR imaging system (Magnetom Concerto, Siemens Medical Solutions, Erlangen, Germany). A T1/T2*-weighted fast-imaging-with-steady-precession (FISP) sequence with an end-to-end latency of 1.2 s facilitated sufficient near real-time MR imaging guidance in all cases. A T1-weighted two dimensional fast-low-angle-shot (FLASH2D) MR sequence identified final needle tip location. Different angles of the needle path had only minimal influence on the appearance of the needle artifact produced by both sequences, resulting in a symmetrical needle tip artifact. The joint cavity was successfully punctured in 79.5% (35/44) of joints, which was followed by intra-articular fluid accumulation in 75% (33/44). Inaccessible joints demonstrated a significantly (p=0.044) higher number of posterior osteophytes (66.7%, 6/9 joints) compared to accessible joints (26%, 9/35 joints). No complications occurred. Table time showed significant shortening over time with average table time of 33 (21–68.5) min. We conclude that MR fluoroscopy-navigated lumbar facet joint injections are feasible and safe.

Radiofrequency ablation of liver metastases

ZusammenfassungDie Leber ist unabhängig vom Primärtumor nach den Lymphknoten die zweithäufigste Lokalisation von Metastasen. Bis zu 50% aller Patienten mit malignen Erkrankungen werden im Verlauf ihrer Erkrankung Lebermetastasen entwickeln, die mit einer signifikanten Morbidität und Mortalität verbunden sind. Obwohl die chirurgische Resektion zu einer verlängerten Überlebenszeit führt, sind nur ca. 20% der Patienten für einen chirurgischen Eingriff geeignet.Die Radiofrequenz-(RF-)Ablation stellt derzeit eine der effektivsten Alternativen und komplementären Methoden bei der Therapie von Lebermetastasen dar. In einem selektierten Patientengut führt die RF-Ablation über den palliativen Einsatz hinaus zu einer kurativen Therapie mit Verlängerung des Überlebens. Die RF-Ablation zeigt sich im Vergleich zu anderen interventionellen Verfahren sicherer (vs. Kryotherapie), effektiver (vs. Ethanolinstillation [PEI], transarterielle Chemoembolisation [TACE]) oder einfacher (vs. Laser). Die RF-Ablation kann perkutan, laparoskopisch oder intraoperativ durchgeführt sowie mit Chemotherapie bzw. chirurgischer Resektion kombiniert werden. Ständige technische Weiterentwicklung der RF-Systeme, ein besseres Verständnis der elektrophysiologischen Prinzipien und ein multidisziplinäres Vorgehen mit Kombinationstherapien werden zu einer Prognoseverbesserung bei Patienten mit Lebermetastasen führen.AbstractThe liver is the second only to lymph nodes as the most common site of metastatic disease irrespective of the primary tumor. Up to 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improvement of the survival time, only approximately 20% of the patients are eligible for surgical intervention.Radiofrequency (RF) ablation represents one of the most important alternatives as well as complementary methods for the therapy of liver metastases. RF ablation can lead in a selected patient group to a palliation or to an increased life expectancy. RF ablation appears either safer (vs. cryotherapy) or easier (vs. laser) or more effective (percutaneous ethanol instillation [PEI], transarterial chemoembolisation [TACE]) in comparison with other minimal invasive procedures.RF ablation can be performed percutaneously, laparoscopically or intraoperatively and may be combined with chemotherapy as well as with surgical resection. Permanent technical improvements of RF systems, a better understanding of the underlying electrophysiological principles and an interdisciplinary approach will lead to a prognosis improvement in patients with liver metastases.

[MRI-guided percutaneous radiofrequency ablation of hepatic neoplasms--first technical and clinical experiences].

Purpose: To evaluate the safety and efficacy of MR-guided radiofrequency ablation (RFA) of hepatic neoplasms. Material and Methods: 16 hepatic neoplasms (1.3-3.0 cm in diameter) in 11 patients were treated by 22 percutaneous RFA sessions during a prospective study. 16 G, MR-compatible cooled-tip electrodes with active lengths of 2 cm and 3 cm, respectively, were placed under MR-guidance in an open 0.2 Tesla MR system (Magnetom Open, Siemens, Erlangen) using fast T 1 -weighted sequences. Pretreatment studies, evaluation of tumor necrosis (one week after last RFA), and further follow-up studies every 3 months were performed using 1.5 Tesla MR systems. Results: The mean procedure time was 2.8 (1.5-3.3)h. Complications related to percutaneous treatment were not encountered. 14 of 16 neoplasms (87%) showed no CM enhancement during MRI after the last RFA and were judged to be completely necrotic. In 11 tumors one treatment session was necessary, in 4 tumors two and in one tumor three. Follow-up studies revealed persistent complete necrosis in 13 of 14 (93%) tumors during a period of 3 - 18 (median: 11.8) months. In 5 patients new intrahepatic tumors developed that were not suitable for further RFA treatment because of their number, size and location, conclusion: MR-guided RFA using single cooled tip electrodes is safe and technically effective for treatment of hepatic neoplasms up to 3 cm in size, however further improvements are necessary.

[CT-guided radiofrequency (RF) ablation of osteoid osteoma: clinical long-term results].

PURPOSE To evaluate CT-guided radiofrequency (RF) ablation of osteoid osteoma using internally cooled monopolar RF electrodes for technical success, complications and clinical long-term success. MATERIALS AND METHODS Between April 1999 and July 2006, 23 patients were treated under general anesthesia with CT-guided RF ablation using an internally cooled monopolar single RF electrode (Cool-tip, Valleylab, TycoHealthcare, Boulder, USA; active tip: 10 mm). For the removal of the nidus, we used either a manual or an automated drill. The technical success was evaluated by a CT scan (MSCT, Siemens Medical Solutions, Forchheim). The clinical long-term success was investigated by questioning patients prior to discharge, and after 6, 12 and 18 months. After 18 months, patients were interviewed on an annual basis. RESULTS The technical success rate was 100 %. The nidus was located in n = 19 cases at the lower extremity and in n = 4 cases at the upper extremity. Minor complications were observed for n = 2 patients. The mean hospitalization time was 1.5 d (1-2 d). The mean follow-up was 75.9 months (18-120 months) for n = 23 patients. No local recurrence was observed. One patient had intermediate pain one week after RF ablation without recurrent symptoms. CONCLUSION CT-guided RF ablation using an internally cooled monopolar single RF electrode is an effective and safe minimally invasive method for the treatment of osteoid osteoma with excellent clinical long-term success.

Radiofrequenzablation von Lebermetastasen

ZusammenfassungDie Leber ist unabhängig vom Primärtumor nach den Lymphknoten die zweithäufigste Lokalisation von Metastasen. Bis zu 50% aller Patienten mit malignen Erkrankungen werden im Verlauf ihrer Erkrankung Lebermetastasen entwickeln, die mit einer signifikanten Morbidität und Mortalität verbunden sind. Obwohl die chirurgische Resektion zu einer verlängerten Überlebenszeit führt, sind nur ca. 20% der Patienten für einen chirurgischen Eingriff geeignet.Die Radiofrequenz-(RF-)Ablation stellt derzeit eine der effektivsten Alternativen und komplementären Methoden bei der Therapie von Lebermetastasen dar. In einem selektierten Patientengut führt die RF-Ablation über den palliativen Einsatz hinaus zu einer kurativen Therapie mit Verlängerung des Überlebens. Die RF-Ablation zeigt sich im Vergleich zu anderen interventionellen Verfahren sicherer (vs. Kryotherapie), effektiver (vs. Ethanolinstillation [PEI], transarterielle Chemoembolisation [TACE]) oder einfacher (vs. Laser). Die RF-Ablation kann perkutan, laparoskopisch oder intraoperativ durchgeführt sowie mit Chemotherapie bzw. chirurgischer Resektion kombiniert werden. Ständige technische Weiterentwicklung der RF-Systeme, ein besseres Verständnis der elektrophysiologischen Prinzipien und ein multidisziplinäres Vorgehen mit Kombinationstherapien werden zu einer Prognoseverbesserung bei Patienten mit Lebermetastasen führen.AbstractThe liver is the second only to lymph nodes as the most common site of metastatic disease irrespective of the primary tumor. Up to 50% of all patients with malignant diseases will develop liver metastases with a significant morbidity and mortality. Although the surgical resection leads to an improvement of the survival time, only approximately 20% of the patients are eligible for surgical intervention.Radiofrequency (RF) ablation represents one of the most important alternatives as well as complementary methods for the therapy of liver metastases. RF ablation can lead in a selected patient group to a palliation or to an increased life expectancy. RF ablation appears either safer (vs. cryotherapy) or easier (vs. laser) or more effective (percutaneous ethanol instillation [PEI], transarterial chemoembolisation [TACE]) in comparison with other minimal invasive procedures.RF ablation can be performed percutaneously, laparoscopically or intraoperatively and may be combined with chemotherapy as well as with surgical resection. Permanent technical improvements of RF systems, a better understanding of the underlying electrophysiological principles and an interdisciplinary approach will lead to a prognosis improvement in patients with liver metastases.

La Résonance Magnétique Interventionnelle en pathologie ostéoarticulaire

Magnetic resonance (MR) imaging is well established for the diagnosis of musculoskeletal diseases. The excellent tissue contrast and the multiplanar imaging capability have both contributed to the improvement of this technique. The development of fast acquisition techniques, sufficient patient access obtained with open magnet configurations and advances in the technology of MR compatible instruments allow a new approach to interventional radiology. These recently commercially available open-bored high-field magnets allow standard interventions such as biopsies or intra-articular infiltrations. Moreover, new interventions e.g. preoperative marking of soft tissue or bone marrow tumors are now possible with the better tissue contrast of MR imaging.

Comparison of a single perfusion device and an internally cooled cluster device: laboratory experience in ex vivo liver tissue with longer duration of energy application.

PURPOSE To determine with comparison of two different monopolar radiofrequency (RF) devices whether a longer duration of energy application has an effect on coagulation necrosis in ex vivo bovine liver tissue. MATERIALS AND METHODS The volume and short- and long-axis diameters of the coagulation were assessed in ex vivo bovine livers after RF application for 5-60 minutes. A power of 60 W was used for the single perfusion applicator (n = 48), and a power of 200 W was used for the internally cooled cluster applicator (n = 48). Reproducibility and coagulation shape were assessed and compared. For statistical evaluation, the mean values of the dimensions were compared by using analysis of variance with the following factors: applicator, RF duration, and their interaction. RESULTS RF application up to 60 minutes produced a mean maximum volume of coagulation of 116.8 cm(3)(95% confidence interval [CI]: 98.4 cm(3), 138.8 cm(3)) for the single perfusion device and 89.5 cm(3)(95% CI: 75.4 cm(3), 106.3 cm(3)) for the internally cooled cluster applicator. For both devices, duration of energy application up to 60 minutes showed a significant interaction for the volume and the short- and long-axis diameters of coagulation (P < .0001). The volumes of coagulation necrosis induced with the internally cooled cluster applicator were more reproducible than those induced with the single perfusion applicator (P < .0001). The shape of the lesion was closer to a sphere (mean shape ratio, 0.98) for the internally cooled cluster than for the single perfusion applicator (mean shape ratio, 1.21) (P < .0001). CONCLUSIONS There is a significant interaction between RF duration and both RF devices influencing the dimensions of coagulation. Longer durations of energy application expand the volume of coagulation with a better reproducibility and more spherical shape of coagulation for the internally cooled cluster device.

MRT-gestützte perkutane Radiofrequenzablation hepatischer Neoplasien - - Erste technische und klinische Erfahrungen -

Purpose: To evaluate the safety and efficacy of MR-guided radiofrequency ablation (RFA) of hepatic neoplasms. Material and Methods: 16 hepatic neoplasms (1.3-3.0 cm in diameter) in 11 patients were treated by 22 percutaneous RFA sessions during a prospective study. 16 G, MR-compatible cooled-tip electrodes with active lengths of 2 cm and 3 cm, respectively, were placed under MR-guidance in an open 0.2 Tesla MR system (Magnetom Open, Siemens, Erlangen) using fast T 1 -weighted sequences. Pretreatment studies, evaluation of tumor necrosis (one week after last RFA), and further follow-up studies every 3 months were performed using 1.5 Tesla MR systems. Results: The mean procedure time was 2.8 (1.5-3.3)h. Complications related to percutaneous treatment were not encountered. 14 of 16 neoplasms (87%) showed no CM enhancement during MRI after the last RFA and were judged to be completely necrotic. In 11 tumors one treatment session was necessary, in 4 tumors two and in one tumor three. Follow-up studies revealed persistent complete necrosis in 13 of 14 (93%) tumors during a period of 3 - 18 (median: 11.8) months. In 5 patients new intrahepatic tumors developed that were not suitable for further RFA treatment because of their number, size and location, conclusion: MR-guided RFA using single cooled tip electrodes is safe and technically effective for treatment of hepatic neoplasms up to 3 cm in size, however further improvements are necessary.