Preliminary clinical experience with laser-induced interstitial thermotherapy in patients with hepatocellular carcinoma

Complications of High Intensity Focused Ultrasound for Patients with Hepatocellular Carcinoma

High intensity focused ultrasound (HIFU) is a noninvasive treatment modality that induces complete coagulative necrosis of a deep tumor through the intact skin. This study was conducted to analyze and evaluate the complications of HIFU for the treatments of hepatocellular carcinoma. A total of 59 patients with hepatocellular carcinoma, with a total of 72 lessions were enrolled in this study. Tumor size ranged from 2.5 to 14.0 cm in diameter, with a mean diameter of 7.6 cm. All patients had accepted HIFU treatment, and the median number of HIFU sessions was 1.32 per patient. Results: The common complications from HIFU therapy were skin burns of various grades (eight cases of grade 1 skin burns, 48 of grade 2, three cases of 3), and pain in the treatment regions (15 cases of mild pain, 37 cases of moderate pain, 7 cased of severe pain). Other systemic complications were relatively rare and included fever (5 cases), hypertension (8 cases), supraventricular tachycardia (3 cases), mild impairment of hepatic function (48 cases), and mild mpairment of renal function (2 cases). Local damage consisted of acute cholecystitis (2 cases), hematuria (6 cases), cholangiectasis (5 cases), light pericardial effusion (2 cases), impairment of peripheral nerves (10 cases), pleural effusion in the right thorax (3 cases), and impairment of vertebral column (1 case). No gastric or intestinal tract perforation, big vessel rupture, or hepatic rupture occurred. Conclusions: HIFU is a minimally invasive treatment for patients with hepatocellular carcinoma; however, there are some systemic and local complications that should be taken into consideration in evaluating HIFU for therapeutic use.

Feasibility of US-guided high-intensity focused ultrasound treatment in patients with advanced pancreatic cancer: initial experience

The study was approved by the university ethics committee, and informed consent was obtained from all patients. The purpose of this study was to prospectively evaluate ultrasonographically guided high-intensity focused ultrasound in the treatment of patients with advanced-stage pancreatic cancer. Eight patients underwent high-intensity focused ultrasound ablation, and laboratory and radiologic examinations were performed after intervention. Changes in symptoms and survival time were noted at follow-up. No complications were observed, and preexisting severe back pain disappeared after intervention. Follow-up images revealed an absence of tumor blood supply and shrinkage of the ablated tumor. Four patients died, and four patients were alive at the time of this writing, with a median survival time of 11.25 months. The authors conclude that high-intensity focused ultrasound ablation is safe and feasible in the treatment of advanced pancreatic cancer.

Clinical application of Nd:YAG laser for the treatment of small hepatocellular carcinoma with new shaped laser probe

BACKGROUND AND OBJECTIVES

Surgical resection of hepatocellular carcinoma (HCC) is not always regarded as the first choice of treatment, because most HCCs develop in cirrhotic liver. It becomes adaptation of minimally invasive treatments for HCC. In animal experiments, we previously reported that our newly developed neodymium:yttrium aluminum garnet (Nd:YAG) laser system could ablate liver tissue in short periods.

STUDY DESIGN/PATIENTS AND METHODS

Six HCC cases (mean diameter; 16.3 +/- 3.50 mm) were enrolled. The Nd:YAG laser generator with a wavelength of 1,064 nm at 10 W of power emitted the laser in a forward fashion and in all patients the laser beam safely irradiated the target lesion.

RESULTS

There was no recurrence of HCC in the laser-ablated area in six patients for duration of 21.8+/- 4.35 months. A local recurrence was found in only one patient.

CONCLUSIONS

This study showed the clinical usefulness of laser ablation in the treatment of HCC.

Extracorporeal high intensity focused ultrasound ablation in the treatment of patients with large hepatocellular carcinoma

BACKGROUND

High intensity focused ultrasound (HIFU) is a noninvasive treatment modality that induces complete coagulative necrosis of a deep tumor through the intact skin. The current study was conducted to determine the safety, efficacy, and feasibility of extracorporeal HIFU in the treatment of patients with hepatocellular carcinoma (HCC).

METHODS

A total of 55 patients with HCC with cirrhosis were enrolled in this prospective, nonrandomized clinical trial. Among them, 51 patients had unresectable HCC. Tumor size ranged from 4 to 14 cm in diameter with mean diameter of 8.14 cm. According to tumor, node, metastasis (TNM) classification, 15 patients corresponded to stage II, 16 to stage IIIA, and 24 to IIIC. All patients had HIFU, and the median number of HIFU session was 1.69. Safety and efficacy of HIFU were assessed in this trial.

RESULTS

No severe side effect was observed in the patients treated with HIFU. Follow-up imaging showed an absence of tumor vascular supply and the shrinkage of treated lesions. Serum alpha-fetoprotein returned to normal level in 34% of patients. The overall survival rates at 6, 12, and 18 months were 86.1%, 61.5%, and 35.3%, respectively. The survival rates were significantly higher in patients in stage II than those in stage IIIA (P = .0132) and in stage IIIC (P = .0265).

CONCLUSION

As a noninvasive therapy, HIFU appears to be effective, safe, and feasible in the treatment of patients with HCC. It may play an important role in the ablation of large tumors.

Termoablação a laser de tumores hepáticos: atualização

A termoablação por raio laser de tumores hepáticos tem despontado como alternativa válida de tratamento em pacientes que não são candidatos a ressecção cirúrgica. O procedimento pode ser realizado por via percutânea, laparoscópica ou por laparotomia, e orientado por métodos de imagem. O objetivo deste trabalho é apresentar o mecanismo de ação deste método, bem como as suas indicações, contra-indicações, complicações e resultados clínicos, baseados em revisão bibliográfica.

Heat-activated Liposomal MR Contrast Agent: Initial in Vivo Results in Rabbit Liver and Kidney

PURPOSE

To evaluate by using in vivo magnetic resonance (MR) imaging the functionality of a liposomal paramagnetic contrast agent with T1 relaxivity that rapidly and markedly increases at temperatures above the gel-to-liquid crystalline phase transition temperature (T(c)) of the liposome membrane.

MATERIALS AND METHODS

Liposomal gadolinium diethylenetriaminepentaacetic acid bis(methylamide) was injected intravenously at a dose of 0.4 or 1.2 mL (containing 10 or 30 micromol of gadolinium, respectively) per kilogram of body weight shortly before the application of focused ultrasound in liver (seven rabbits) or kidney (three rabbits). VX2 tumors had been implanted in liver in four of the rabbits. Eighteen locations in liver (13 in normal tissue, five in tumor) and 12 locations in kidney were sonicated. MR thermometry was performed during sonications. Signal intensity enhancement was evaluated on T1-weighted images acquired after the tissue cooled, and enhanced zones were compared with isotherms at T(c) of the liposome membrane (approximately 57 degrees C) by using Bland-Altman analysis. In liver, enhanced zones also were compared with areas of histologically verified thermal damage. The threshold temperature of enhancement at T1-weighted imaging was verified by monitoring the signal intensity increase after 10 sonications at varied powers in two locations in normal liver tissue.

RESULTS

Persistent enhancement was observed on T1-weighted images at all sonicated liver locations. In liver, enhanced zones on T1-weighted images were contiguous both with 57 degrees C isotherms (25 measurements; mean difference +/- SD, 0.4 mm +/- 1.2) and with histologically verified areas of necrosis (seven measurements; mean difference +/- SD, 0.1 mm +/- 0.9). The threshold temperature of enhancement at T1-weighted imaging in normal liver was 53 degrees -57 degrees C. In kidney, enhanced zones on T1-weighted images did not match the isotherms.

CONCLUSION

The liposomal contrast agent was effective at in vivo MR thermometry in liver but not in kidney.

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.

Ex vivo evaluation of novel miniaturized laser-induced interstitial thermotherapy applicators for effective small-volume tissue ablation

RATIONALE AND OBJECTIVES

For effective small-volume tissue ablation in clinical and experimental settings, smaller laser-induced interstitial thermotherapy (LITT) applicator designs are required. The aim of this study was to compare the ablation properties of recently developed ultrasmall and small to standard LITT applicators.

METHODS

Laser-induced interstitial thermotherapy was performed on liver samples using ultrasmall, small, and standard LITT applicators. Thermotherapy was monitored by magnetic resonance imaging, and lesion sizes were measured for each image. True lesion sizes were then determined macroscopically and by histology.

RESULTS

For continuous laser application over 5 minutes, maximum power settings were 5 W for the ultrasmall and small applicators and 10 W for the standard applicator. Given identical LITT settings, lesion volume measured by magnetic resonance imaging was significantly larger and histological tissue damage was more severe with the ultrasmall and small applicators than with the standard applicator.

CONCLUSIONS

Small and ultrasmall LITT applicators can be used for effective tissue ablation of small target volumes in experimental and clinical applications.

Magnetic resonance image-guided thermal ablations

Magnetic resonance imaging (MRI)-based monitoring has been shown in recent years to enhance the effectiveness of minimally or noninvasive thermal therapy techniques, such as laser, radiofrequency, microwave, ultrasound, and cryosurgery. MRI's unique soft-tissue contrast and ability to image in three dimensions and in any orientation make it extremely useful for treatment planning and probe localization. The temperature sensitivity of several intrinsic parameters enables MRI to visualize and quantify the progress of ongoing thermal treatment. MRI is sensitive to thermally induced tissue changes resulting from the therapies, giving the physician a method to determine the success or failure of the treatment. These methods of using MRI for planning, guiding, and monitoring thermal therapies are reviewed.

Microwave coagulation therapy: ex vivo comparison of MR imaging and histopathology

We compared the findings of magnetic resonance (MR) images and pathological examination to determine whether or not MR images reflect pathological changes following microwave coagulation therapy (MCT) on liver tissue. We used microwave (generating frequency 2450 Mhz, wave length 12 cm, output 50 W, 60 second duration) to irradiate six canine livers under general anesthesia. After the animals were sacrificed, the livers were resected. The irradiated regions were cut with margins and divided into two pieces, one for MR study, and the other for pathological examination. The findings were compared. From the center to the marginal layer, the irradiated region presented 4/3 laminal patterns on T1/T2-weighted images: low/high, high/low, very high/high, and iso-low/high intensity. On gradient-echo imaging, the irradiated regions presented no decreasing signals using several echo time lengths. With hematoxylin and eosin stain, MR laminar patterns reflected the histopathological changes, as follows: a tissue loss area surrounding the inserted needle, low/high; decreased sinusoidal width with/without necrotic tissue, high/low; sinusoidal width dilation at the periphery, very high/high; and fatty degenerated tissue surrounding the irradiated area at the boundary of the normal hepatocytes, iso-low/high. The MR signal intensity, which reflected the histopathological changes, presented tissue characterization after MCT, and the macromolecular hydration effect influenced the high intensity on T1-weighted images.

MRI of thermally denatured blood: methemoglobin formation and relaxation effects

Focal regions of T1-shortening have been observed in magnetic resonance imaging (MRI)-monitored thermal ablations of perfused tissues. The aims of this study were two-fold: to find evidence for heat-induced conversion of hemoglobin (Hb) to methemoglobin (mHb), and to investigate the effects of heat treatment of in-vitro blood components upon their MR relaxation times. Spectrophotometric studies were performed to confirm the heat-induced formation of methemoglobin. Preparations of whole and fractionated blood, previously submitted to elevated temperatures of 40 degrees C to 80 degrees C, were imaged and the relaxation times were calculated. Optical absorption spectra of samples containing free Hb, heated to 60 degrees C, showed increased light absorption at 630 nm, evident of mHb presence. Short T1 values in whole blood (1.13 s) and packed red blood cell (0.65 s) compartments, heated at 60 degrees C, compared to their baseline values (1.62 s and 0.83 s, respectively), were attributed to mHb formation. In relation to MRI-guided thermal interventions, these results suggest a possible explanation for observation of hyperintense regions on T1-weighted images.