MR-guided neurolytic celiac plexus ablation: an evaluation of effect and injection spread pattern in cancer patients with celiac tumor infiltration.

OBJECTIVE: The purpose of this study was to evaluate the feasibility, the initial accuracy, and the effects of the MR-guided neurolytic celiac plexus ablation as a method to treat cancer-induced chronic abdominal pain. METHODS: Thirteen celiac plexus ablations were performed for 12 patients. A 0.23-T open MRI scanner with optical navigation was used for procedural guidance. As an adjunct to the MR-guided needle positioning, the needle location was confirmed with saline injection and consequent MR imaging (STIR sequence). The spread of the ablative injection material (alcohol-lidocaine mix) was observed by repeating this sequence after the therapeutic injection. Pain scores from seven patients (eight ablations) were used to assess the therapy effect. RESULTS: MR guidance allowed adequate needle positioning and visualization of injection material in all cases. The rest pain scores significantly decreased from 4 (median) at baseline to 1 (median) at 2 weeks (p < 0.05). Average and worst pain experienced during the past week were significantly lower at the 2-week time point compared with the baseline (p < 0.05). However, the intervention did not result in reduction of opioid use at 2 weeks. CONCLUSIONS: MR guidance is an accurate and safe method for celiac plexus ablation with positive therapeutic effect.

Liver tumor laser ablation - increase in the subacute ablation lesion volume detected with post procedural MRI.

BACKGROUND: The use of image-guided thermoablative methods in liver tumor treatment has expanded rapidly due to encouraging results and advanced imaging. However, little is known about the treatment-induced tissue response and effects on imaging findings during the subacute post procedural period. PURPOSE: To study the development of subacute ablation zone volume with magnetic resonance imaging (MRI) after laser-mediated liver tumor thermal therapy. MATERIAL AND METHODS: In all, 16 laser ablations were performed on 16 liver tumors resulting in 16 ablation zones in 11 consecutive patients. A low-field 0.23 T C-arm MRI scanner was used for imaging and procedural guidance. Repeated dynamic contrast-enhanced T1, contrast-enhanced T1 FSE, and T2 FSE studies of liver were performed at 0 and 72 h after the procedure. Ablation zone volumes were registered from the acquired image data. RESULTS: MRI scans showed a significant increase of ablation volume in all imaging sequences obtained at 72 h after the initial therapy. CONCLUSION: After laser ablation, there is a progressive perfusion decrease in the ablation site leading to an increase in the ablation volume. Post procedural baseline MRI at 72 h from the treatment provides more precise information about the ablation result than can be obtained with immediate post procedural MRI.

MRI-guided percutaneous laser ablation of small renal cell carcinoma: Initial clinical experience.

BACKGROUND: The number of detected small renal cell carcinomas (RCCs) has been rising, largely due to advances in imaging. Open surgical resection is the standard management of small RCCs; however, imaging-guided percutaneous ablative therapies have emerged as a minimally invasive treatment alternative, especially for patients who are poor candidates for surgery. PURPOSE: To evaluate the initial clinical experience of magnetic resonance imaging (MRI)-guided percutaneous laser ablation of small RCCs. MATERIAL AND METHODS: Eight patients with 10 tumors were treated with percutaneous MRI-guided laser ablation. All tumors (diameter range 1.5-3.8 cm, mean 2.7 cm) were biopsy-proven RCCs. By using a 0.23 T open MRI system and general anesthesia in patients, one to four (mean 2.6) laser fibers were placed and the tumors were ablated under near real-time MRI control by observing the signal void caused by the temperature change in the heated tissue. The treatment was considered successful if the tumor showed no contrast enhancement at follow-up imaging. RESULTS: All except one tumor were successfully ablated in one session. The first patient treated showed enhancing residual tumor in post-procedural MRI; she has thus far declined retreatment. One complication, a myocardial infarction, occurred; all other patients tolerated the procedure well. No local recurrence was discovered during the follow-up (range 12-30 months, mean 20 months). CONCLUSION: In this small group of patients with relatively short follow-up period, MRI-guided percutaneous laser ablation proved to be a promising treatment option for small RCCs.

Feasibility of MR imaging-guided percutaneous drainage of pancreatic fluid collections.

PURPOSE: To assess the feasibility and safety of magnetic resonance (MR) imaging-guided percutaneous drainage of pancreatic fluid collections in an open configuration low field MR imaging system. MATERIALS AND METHODS: Ten patients with pancreatic fluid collections were examined prospectively. Five of the fluid collections were symptomatic pseudocysts and five were pancreatic abscesses. All percutaneous drainages were performed solely under MR imaging guidance with a 0.23-T open configuration C-arm shaped MR imaging scanner with interventional optical tracking. Every step of the procedure was monitored using balanced fast field echo sequences. In each case, the drainage of the fluid collection was performed with a MR imaging-compatible drainage kit using the Seldinger technique. The kit included an 18-gauge needle, a 0.035-inch stiff guide wire, 6-F and 8-F dilators, and an 8-F pigtail drainage catheter. RESULTS: All drainage catheters could successfully be placed into the pancreatic fluid collections under MR imaging guidance. Visualization of the needle, dilator, and drainage catheter was excellent. However, visualization of the guide wire was suboptimal. The mean time needed for the MR-guided drainage procedure was 44 minutes. No immediate complications occurred. The clinical success rate of the percutaneous drainage was 70%; three patients were subsequently treated surgically. There were no deaths. The average duration of catheterization was 40 days. CONCLUSION: MR imaging-guided percutaneous drainage of pancreatic fluid collections is feasible and safe. The presented technique has limitations--lack of real-time imaging control and small selection of MR imaging-compatible devices--that necessitate further technical developments before the procedure can be recommended for routine clinical use.

Arterial embolization and prophylactic catheterization for the treatment for severe obstetric hemorrhage*.

BACKGROUND: To evaluate indications, efficacy, and complications associated with arterial embolization and prophylactic balloon catheterization in the management of obstetric hemorrhage at a university hospital. METHODS: Twenty-two women underwent arterial embolization between February 2001 and November 2003 for the treatment for primary postpartum hemorrhage resulting from abnormal placentation (n=11), uterine atony (n=7), paravaginal laceration (n=3), and disseminated intravascular coagulopathy (n=1). Blood loss was between 3.2 and 15 l. In seven patients, abnormal placentation was diagnosed prenatally and in these patients balloon catheterization was performed prophylactically before elective cesarean section. RESULTS: Of the seven patients, who underwent prophylactic catheterization, embolization was successful in five resulting in adequate hemostasis. Hysterectomy was performed in three, in two patients for uncontrolled hemorrhage and in one patient for placental invasion to bladder. There were no complications associated with prophylactic catheterization and embolization. The other 15 patients were treated in an emergency setting. In eight patients, embolization was performed as a primary surgery, and it was successful in six. In the other seven patients, hysterectomy was performed as an emergency surgery, but bleeding continued. Of these, in six patients, hemostasis was achieved with embolization. Complications associated with emergency embolization were observed in three patients. These were thrombosis of left popliteal artery, vaginal necrosis, and paresthesia of the right leg. CONCLUSIONS: Arterial embolization is of significant value in treating obstetric hemorrhage. Prophylactic insertion of balloon catheters before cesarean section seems to be a safe and effective method in controlling anticipated bleeding. In patients with persistent bleeding following cesarean section and hysterectomy, embolization could be a primary procedure before re-surgery.

Interventional and intraoperative MRI at low field scanner--a review.

Magnetic resonance imaging (MRI) is a cutting edge imaging modality in detecting diseases and pathologic tissue. The superior soft tissue contrast in MRI allows better definition of the pathology. MRI is increasingly used for guiding, monitoring and controlling percutaneous procedures and surgery. The rapid development of interventional techniques in radiology has led to integration of imaging with computers, new therapy devices and operating room like conditions. This has projected as faster and more accurate imaging and hence more demanding procedures have been applied to the repertoire of the interventional radiologist. In combining features of various other imaging modalities and adding some more into them, interventional MRI (IMRI) has potential to take further the interventional radiology techniques, minimally invasive therapies and surgery. The term "Interventional MRI" consists in short all those procedures, which are performed under MRI guidance. These procedures can be either percutaneous or open surgical of nature. One of the limiting factors in implementing MRI as guidance modality for interventional procedures has been the fact, that most widely used magnet design, a cylindrical magnet, is not ideal for guiding procedures as it does not allow direct access to the patient. Open, low field scanners usually operating around 0.2 T, offer this feature. Clumsy hardware, bad patient access, slow image update frequency and strong magnetic fields have been other limiting factors for interventional MRI. However, the advantages of MRI as an imaging modality have been so obvious that considerable development has taken place in the 20-year history of MRI. The image quality has become better, ever faster software, new innovative sequences, better MRI hardware and increased computing power have accelerated imaging speed and image quality to a totally new level. Perhaps the most important feature in the recent development has been the introduction of open configuration low field MRI devices in the early 1990s; this enabled direct patient access and utilization of the MRI as an interventional device. This article reviews the current status of interventional and intraoperative MRI with special emphasis in low field surrounding.