Hepatic metastases: interstitial laser photocoagulation with real-time US monitoring and dynamic CT evaluation of treatment

Osteoid osteoma: percutaneous laser ablation and follow-up in 114 patients

PURPOSE

To retrospectively evaluate the effectiveness of interstitial laser ablation (ILA) as a curative treatment of osteoid osteoma.

MATERIALS AND METHODS

Ethical review board approval was obtained for the retrospective study. Informed consent was waived. From June 1994 to June 2004, 114 patients (mean age, 22.3 years) suspected of having osteoid osteoma underwent ILA with a diode laser (805 nm). An optical fiber was introduced into the nidus of the osteoid osteoma, and 400-3000 J of energy was delivered, depending on the size and location of the nidus. Twelve spinal osteoid osteomas were treated; in five of these cases, the nidus was located fewer than 8 mm from the adjacent nerve roots, and slow epidural or periradicular infusion of normal saline was used to avoid thermal damage to neurologic structures. Pain was evaluated with a visual analog scale (VAS) and medication. ILA was considered successful (score, 0) when complete pain relief was achieved (VAS score, <1) without medication.

RESULTS

One week after ILA, 112 patients had a score of 0. One week after ILA, one patient had pain that persisted for 2 months because of reflex sympathetic dystrophy. At follow-up (mean, 58.5 months; range, 13-130 months), six patients had recurrence of pain from 6 weeks to 27 months after the initial ILA. These recurrences were treated successfully with a second ILA. Only one unsuccessful treatment was encountered.

CONCLUSION

Percutaneous ILA is an effective treatment for osteoid osteoma.

Determination of the Minimum Temperature Required for Selective Photothermal Destruction of Cancer Cells with the Use of Immunotargeted Gold Nanoparticles

Laser photothermal therapy of cancer with the use of gold nanoparticles immunotargeted to molecular markers on the cell surface has been shown to be an effective modality to selectively kill cancer cells at much lower laser powers than those needed for healthy cells. To elucidate the minimum light dosimetry required to induce cell death, photothermal destruction of two cancerous cell lines and a noncancerous cell line treated with antiepidermal growth factor receptor (anti-EGFR) antibody-conjugated gold nanoparticles is studied, and a numerical heat transport model is used to estimate the local temperature rise within the cells as a result of the laser heating of the gold nanoparticles. It is found that cell samples with higher nanoparticle loading require a lower incident laser power to achieve a certain temperature rise. Numerically estimated temperatures of 70-80 degrees C achieved by heating the gold particles agree well with the measured threshold temperature for destruction of the cell lines by oven heating and those measured in an earlier nanoshell method. Specific binding of anti-EGFR antibody to cancerous cells overexpressing EGFR selectively increases the gold nanoparticle loading within cancerous cells, thus allowing the cancerous cells to be destroyed at lower laser power thresholds than needed for the noncancerous cells. In addition, photothermal therapy using gold nanoparticles requires lower laser power thresholds than therapies using conventional dyes due to the much higher absorption coefficient of the gold nanoparticles.

Dynamic modeling of photothermal interactions for laser-induced interstitial thermotherapy: parameter sensitivity analysis

A two-dimensional model was developed to model the effects of dynamic changes in the physical properties on tissue temperature and damage to simulate laser-induced interstitial thermotherapy (LITT) treatment procedures with temperature monitoring. A modified Monte Carlo method was used to simulate photon transport in the tissue in the non-uniform optical property field with the finite volume method used to solve the Pennes bioheat equation to calculate the temperature distribution and the Arrhenius equation used to predict the thermal damage extent. The laser light transport and the heat transfer as well as the damage accumulation were calculated iteratively at each time step. The influences of different laser sources, different applicator sizes, and different irradiation modes on the final damage volume were analyzed to optimize the LITT treatment. The numerical results showed that damage volume was the smallest for the 1,064-nm laser, with much larger, similar damage volumes for the 980- and 850-nm lasers at normal blood perfusion rates. The damage volume was the largest for the 1,064-nm laser with significantly smaller, similar damage volumes for the 980- and 850-nm lasers with temporally interrupted blood perfusion. The numerical results also showed that the variations in applicator sizes, laser powers, heating durations and temperature monitoring ranges significantly affected the shapes and sizes of the thermal damage zones. The shapes and sizes of the thermal damage zones can be optimized by selecting different applicator sizes, laser powers, heating duration times, temperature monitoring ranges, etc.

Percutaneous Radiofrequency Ablation of Hepatic Tumors: Postablation Syndrome

OBJECTIVE

Our objective was to define the spectrum and possible predictors of symptoms that occur in patients after percutaneous radiofrequency ablation of hepatic tumors.

SUBJECTS AND METHODS

We performed 50 consecutive percutaneous radiofrequency ablation sessions on 39 patients with a total of 89 liver tumors. All patients had pre- and postablation laboratory studies and CT or MRI scans. After treatment, patients were followed for 3 weeks with a standardized questionnaire to assess for postablation symptoms. Comparisons of the presence or absence of symptoms were made for the laboratory test values, liver volumes, and pre- and postablation tumor volumes.

RESULTS

Postablation symptoms occurred in 14 of 39 (36%) patients after 17 of 50 (34%) ablation sessions. Symptoms consisted of fever (16/17), malaise (12/17), chills (6/17), delayed pain (5/17), and nausea (2/17). On average, the symptoms presented 3 days after ablation and lasted 5 days. Statistically significant (p < 0.01) predictors of symptoms were tumor volumes > 50 cm3 (4.5 cm diameter), ablated tissue volumes > 150 cm3 (6.5 cm diameter), a difference between preablation tumor volume and the volume of tissue ablated > 125 cm3, or postablation aspartate aminotransferase levels > 350 IU/L.

CONCLUSION

Approximately one third of patients undergoing percutaneous radiofrequency ablation of hepatic tumors develop delayed, transient flulike symptoms that can be treated conservatively and are significantly related to the volume of tissue ablated. Familiarity with this postablation syndrome should facilitate appropriate management of affected patients.

Radio-frequency ablation of colorectal liver metastases in 167 patients

The objective of this paper is to report our results from a prospective study of 167 patients with colorectal liver metastases treated with radio-frequency ablation (RFA). Three hundred fifty-four treatments were performed in 167 patients, 99 males, mean age 57 years (34-87). The mean number of metastases was 4.1 (1-27). The mean maximum diameter was 3.9 cm (1-12). Fifty-one (31%) had stable/treated extra-hepatic disease. Treatments were performed under general anaesthesia using US and CT guidance and single or cluster water-cooled electrodes (Valleylab, Boulder, CO). All patients had been rejected for or had refused surgical resection. Eighty percent received chemotherapy. Survival data were stratified by tumour burden at the time of first RFA. The mean number of RFA treatments was 2.1 (1-7). During a mean follow-up of 17 months (0-89), 72 developed new liver metastases and 71 developed progressive extra-hepatic disease. There were 14/354 (4%) major local complications and 22/354 (6%) minor local complications. For patients with < or =5 metastases, maximum diameter < or =5 cm and no extra-hepatic disease, the 5-year survival from the time of diagnosis was 30% and from the time of first thermal ablation was 26%. Given that the 5-year survival for operable patients is a median of 32%, our 5-year survival of 30% is promising.

Thyroid Tissue: US-guided Percutaneous Laser Thermal Ablation

PURPOSE

To evaluate in vivo the safety and effectiveness of percutaneous laser thermal ablation (LTA) in the debulking of thyroid lesions.

MATERIALS AND METHODS

Twenty-five adult patients at poor surgical risk with cold nodules (n = 8), autonomously hyperfunctioning thyroid nodules (n = 16), or anaplastic carcinoma (n = 1) underwent LTA. One to four 21-gauge spinal needles were inserted with ultrasonographic (US) guidance into the thyroid lesions. A 300-microm-diameter quartz optical fiber was advanced through the sheath of the needle. Nd:YAG laser was used with output power of 3-5 W. Side effects, complications, and clinical and hormonal changes were evaluated at the end of LTA and during follow-up. Linear regression analysis was used to investigate the correlation between energy delivered and reduction in nodule volume. Volume of induced necrosis and reduction in nodule volume were assessed with US or computed tomography.

RESULTS

LTA was performed without difficulties in 76 LTA sessions. After treatment with 5 W, two patients experienced mild dysphonia, which resolved after 48 hours and 2 months. Improvement of local compression symptoms was experienced by 12 of 14 (86%) patients. Thyroid-stimulating hormone (TSH) was detectable in five of 16 (31%) patients with hyperfunctioning nodules at 6 months after LTA. Volume of induced necrosis ranged from 0.8 to 3.9 mL per session. Anaplastic carcinoma treated with four fibers yielded 32.0 mL of necrosis. Echo structure and baseline volume did not influence response. Energy load and reduction in nodule volume were significantly correlated (r(2) =.75, P <.001). Mean nodule volume reduction at 6 months in hyperfunctioning nodules was 3.3 mL +/- 2.8 (62% +/- 21.4 [SD]) and in cold nodules was 7.7 mL +/- 7.5 (63% +/- 13.8).

CONCLUSION

LTA may be a therapeutic tool for highly selected problems in the treatment of thyroid lesions.

Laser Therapy of Breast Cancer with 3-Year Follow-up

Breast cancer is the commonest female malignancy in the United States and is increasingly being detected at a non-palpable stage by annual mammography. Minimally invasive methods of its local treatment have been recently introduced as alternative to its surgical removal. The case reported in this article illustrates the advantages of in-situ ablation with minimal discomfort to the patient and deformity of the breast. More importantly, it demonstrates the absence of any adverse effect on health and survival of the patient during this intermediate period of follow-up.

Quality of life and outcome of ultrasound-guided laser interstitial thermo-therapy for non-resectable liver metastases of colorectal cancer

OBJECTIVE

Patients with non-resectable liver metastases of colorectal cancer have poor prognosis and are mainly treated by palliative chemotherapy. Laser interstitial thermo-therapy is an innovative minimal invasive procedure for local tumour destruction within solid organs. The aim of the study was to investigate quality of life and outcome of ultrasound-guided laser interstitial thermo-therapy (US-LITT) in patients with liver metastases of colorectal cancer.

METHODS

In this prospective non-randomized study, 45 patients with liver metastases of colorectal cancer were palliatively treated by US-LITT. Patient survival was analysed by the Kaplan-Meier method and the quality of life by questionnaire C30 of the European Organisation for Research and Treatment of Cancer before, and 1 week, 1 month, and 6 months after initiation of US-LITT.

RESULTS

Median survival after initiation of US-LITT was 8.5 +/- 0.7 months with a range of 1.5-18 months. Body weight was constant 1 month after US-LITT. In the multivariate analyses, quality-of-life symptoms and functioning scales did not deteriorate in patients alive at 6 months after initiation of US-LITT. Univariate analyses outlined a significant increase of the pain subscale before and at 1 week after US-LITT.

CONCLUSIONS

This study first describes the quality of life in patients with liver metastases of colorectal cancer treated by US-LITT. Potential benefits of the minimal invasive procedure could be prolonged survival time by preserved quality of life, but this first impression needs to be verified in a comparative study.

The emergent role of focal liver ablation techniques in the treatment of primary and secondary liver tumours

Only 20% of patients with primary or secondary liver tumours are suitable for resection because of extrahepatic disease or the anatomical distribution of their disease. These patients could be treated by ablation of the tumour, thus preserving functioning liver. This study presents a detailed review of established and experimental ablation procedures. The relative merits of each technique will be discussed and clinical data regarding the efficacy of the techniques evaluated. A literature search from 1966 to 2003 was undertaken using Medline, Pubmed and Web of Science databases. Keywords were Hepatocellular carcinoma, liver metastases, percutaneous ethanol injection, cryotherapy, microwave coagulation therapy, radiofrequency ablation, interstitial laser photocoagulation, focused high-intensity ultrasound, hot saline injection, electrolysis and acetic acid injection. Ablative techniques offer a promising therapeutic modality to treat unresectable tumours. Large-scale randomised controlled trials are required before widespread acceptance of these techniques can occur.

Nanoshell-mediated near-infrared thermal therapy of tumors under magnetic resonance guidance

Metal nanoshells are a class of nanoparticles with tunable optical resonances. In this article, an application of this technology to thermal ablative therapy for cancer is described. By tuning the nanoshells to strongly absorb light in the near infrared, where optical transmission through tissue is optimal, a distribution of nanoshells at depth in tissue can be used to deliver a therapeutic dose of heat by using moderately low exposures of extracorporeally applied near-infrared (NIR) light. Human breast carcinoma cells incubated with nanoshells in vitro were found to have undergone photothermally induced morbidity on exposure to NIR light (820 nm, 35 W/cm2), as determined by using a fluorescent viability stain. Cells without nanoshells displayed no loss in viability after the same periods and conditions of NIR illumination. Likewise, in vivo studies under magnetic resonance guidance revealed that exposure to low doses of NIR light (820 nm, 4 W/cm2) in solid tumors treated with metal nanoshells reached average maximum temperatures capable of inducing irreversible tissue damage (DeltaT = 37.4 +/- 6.6 degrees C) within 4-6 min. Controls treated without nanoshells demonstrated significantly lower average temperatures on exposure to NIR light (DeltaT < 10 degrees C). These findings demonstrated good correlation with histological findings. Tissues heated above the thermal damage threshold displayed coagulation, cell shrinkage, and loss of nuclear staining, which are indicators of irreversible thermal damage. Control tissues appeared undamaged.

Interstitial laser thermotherapy for liver tumours

BACKGROUND

Primary hepatocellular carcinoma (HCC) and metastases from colorectal cancer are the most common malignant liver tumours. Surgical resection is the optimum treatment in suitable patients. Interstitial laser thermotherapy (ILT) is gaining acceptance for the treatment of irresectable liver tumours and as a potential alternative to surgery. An understanding of the principles of therapy and review of clinical outcomes may allow better use of this technology.

METHOD

An electronic search using the Medline database was performed for studies on the treatment of hepatic malignancy published between January 1983 and February 2003.

RESULTS

Current information on the efficacy of ILT is based on prospective studies. ILT appears to be a safe and minimally invasive technique that consistently achieves tumour destruction. The extent of destruction depends on the fibre design, delivery system, tumour size and tumour biology. Real-time magnetic resonance imaging provides the most accurate assessment of laser-induced tumour necrosis. In selected patients with HCC and colorectal cancer liver metastases, ILT achieves complete tumour necrosis, provides long-term local control, and improves survival, compared with the natural history of the disease. In addition, ILT has survival benefits for patients with other tumour types, especially those with isolated liver metastases from a breast cancer primary.

CONCLUSION

ILT improves overall survival in specific patients with liver tumours. Advances in laser technology and refinements in technique, and a better understanding of the processes involved in laser-induced tissue injury, may allow ILT to replace surgery as the procedure of choice in selected patients with liver malignancies.

Assessment of proliferating cell nuclear antigen activity using digital image analysis in breast carcinoma following magnetic resonance-guided interstitial laser photocoagulation

This study examines proliferative activity in tumor cells of patients with histologically documented invasive breast carcinoma treated with magnetic resonance-guided interstitial laser photocoagulation (MR-GILP). Immunohistochemical marker for proliferating cell nuclear antigen (PCNA), a nuclear protein abundant in actively proliferating cells, is used. The study demonstrates the effectiveness of MR-GILP in ablating tumor cells of infiltrating breast cancer. The diagnosis of infiltrating breast carcinoma was confirmed by core needle biopsies. Using a specially designed magnetic resonance imaging (MRI) device, rotating delivery of excitation off-resonance (RODEO), tumors were measured ranging from 1.8 to 4.0 cm in greatest dimension. Seven formalin-fixed, paraffin-embedded archival tissues from seven patients with infiltrating carcinoma, status post-MR-GILP, were analyzed. Using PCNA immunoperoxidase (Biomeda Corp.), the proliferative capability of the remaining tumor cells around the focus of laser photocoagulation was determined. The lesions were digitally acquired using a Nikon Eclipse E800 microscope with an automated stage. Images were analyzed using Cool SNAP image editing software (version 1.0). Appropriate thresholds were set for positive staining and limited concentric radial measurements of equal area between all samples were compared at radial millimeter intervals from the center of laser ablation. The integrated area occupied by PCNA-positive cells per radial millimeter from the charcoal site (the center of the laser) increased as the distance from this site increased (a mean average at each radial measurement revealed: at the 1 mm radius the positive integrated area was 0.0024 mm2; at 2 mm, 0.0145 mm2; at 3 mm, 0.0351 mm2; at 4 mm, 0.0696 mm2; at 5 mm, 0.1025 mm2; and at 6 mm, 0.1263 mm2). MR-GILP is an effective mean of ablating breast carcinoma. This treatment option may represent an alternative to lumpectomy for a single lesion < or =1 cm, or make patients with two separate lesions eligible for lumpectomy.

Thermal ablative therapy for malignant liver tumors: a critical appraisal

The management of primary and secondary malignant liver tumors poses a great challenge to clinicians. Although surgical resection is the gold-standard treatment, most patients have unresectable malignant liver tumors. Over the past decade, various modalities of loco-regional therapy have gained much interest. Among them, thermal ablative therapy, including cryotherapy, microwave coagulation, interstitial laser therapy, and radiofrequency ablation (RFA), have been proven to be safe and effective. Despite the effective tumor eradication achieved within cryotherapy, the underlying freeze/thaw mechanism has resulted in serious complications that include bleeding from liver cracking and the 'cryoshock' phenomenon. Thermal ablation using microwave and laser therapy for malignant liver tumors is curative and is associated with minimal complications. However, this treatment modality is effective only for tumors <3 cm diameter. Radiofrequency ablation seems to be the most promising form of thermal ablative therapy in terms of a lower complication rate and a larger volume of ablation. However, its use is restricted by the difficulty encountered when using imaging studies to monitor the areas of ablation during and after the procedure. Moreover, the techniques of RFA need to be refined in order to achieve the same oncological radicality of malignant liver tumors as achieved by surgical resection. As each of the loco-regional therapies has its own advantages and limitations, a multidisciplinary approach using a combination of therapies will be the future trend for the management of malignant liver tumors.

Percutaneous local ablative therapy for hepatocellular carcinoma: a review and look into the future

OBJECTIVE

To review and compare treatment result for percutaneous local ablative therapy (PLAT) with surgical resection in the treatment of small hepatocellular carcinoma (HCC).

SUMMARY BACKGROUND DATA

PLAT is indicated for small unresectable HCC localized to the liver. From the use of ethanol to the latest technology of radiofrequency ablation, ablative techniques have been refined and their role in the management of HCC established. This review aims to give an overview of various ablative methods, including their efficacy, indications, and limitations, and also tries to look into the future of clinical trials in PLAT.

METHODS

The authors reviewed recent papers in the English medical literature about the use of local ablative therapy for HCC. Focus was given to the results of treatment in terms of local control, progression-free survival, and overall survival, and to compare treatment results with those of surgery.

RESULTS

PLAT for small HCC (<5 cm) with thermal ablation (radiofrequency ablation or microwave coagulation) can achieve effective local control of disease and is superior to ethanol injection. Progressive disease in untreated areas is a common reason for failure. Overall progression-free survival is similar to that of surgical resection.

CONCLUSIONS

Thermal ablation gives good local control of small HCC, is superior to ethanol, and may be comparable to surgical resection in long-term outcome.

Interstitial ablative techniques for hepatic tumours

BACKGROUND

Most patients with liver tumours are not suitable for surgery but interstitial ablative techniques may control disease progression and improve survival rates.

METHODS

A review was undertaken using Medline of all reported studies of cryoablation, radiofrequency ablation, microwave ablation, interstitial laser photocoagulation, high-intensity focused ultrasound and ethanol ablation of primary liver tumours and hepatic metastases.

RESULTS

Although there are no randomized clinical trials, cryoablation, thermal ablation and ethanol ablation have all been shown to be associated with improved palliation in patients with primary and secondary liver cancer. The techniques can be undertaken safely with minimal morbidity and mortality.

CONCLUSION

Although surgical resection remains the first line of treatment for selected patients with primary and secondary liver malignancies, interstitial ablative techniques are promising therapies for patients not suitable for hepatic resection or as an adjunct to liver surgery.

Percutaneous local ablative therapy for hepatocellular carcinoma: a review and look into the future

OBJECTIVE

To review and compare treatment result for percutaneous local ablative therapy (PLAT) with surgical resection in the treatment of small hepatocellular carcinoma (HCC).

SUMMARY BACKGROUND DATA

PLAT is indicated for small unresectable HCC localized to the liver. From the use of ethanol to the latest technology of radiofrequency ablation, ablative techniques have been refined and their role in the management of HCC established. This review aims to give an overview of various ablative methods, including their efficacy, indications, and limitations, and also tries to look into the future of clinical trials in PLAT.

METHODS

The authors reviewed recent papers in the English medical literature about the use of local ablative therapy for HCC. Focus was given to the results of treatment in terms of local control, progression-free survival, and overall survival, and to compare treatment results with those of surgery.

RESULTS

PLAT for small HCC (<5 cm) with thermal ablation (radiofrequency ablation or microwave coagulation) can achieve effective local control of disease and is superior to ethanol injection. Progressive disease in untreated areas is a common reason for failure. Overall progression-free survival is similar to that of surgical resection.

CONCLUSIONS

Thermal ablation gives good local control of small HCC, is superior to ethanol, and may be comparable to surgical resection in long-term outcome.

Magnetic resonance imaging-guided laser thermal ablation of renal tumours

OBJECTIVE

To test the hypothesis that magnetic resonance imaging (MRI)-guided laser thermal ablation (LTA) of inoperable renal tumours is a safe, tolerable and potentially effective treatment.

PATIENTS AND METHODS

Nine patients (aged 56-81 years) with malignant renal tumours underwent percutaneous LTA under MRI guidance in a 0.5 T open magnet. Real-time colour thermal mapping was used to monitor tumour ablation, and the follow-up was with gadolinium-enhanced MRI at 6 weeks and (where appropriate) 3-4 months after the procedure. Tumour volume and percentage tumour enhancement before and after ablation were compared. The percentage of tumour ablated on real-time T1-weighted thermal maps was compared with that on gadolinium-enhanced follow-up MRI.

RESULTS

The mean (range) follow-up was 16.9 (3-32) months after the first ablation. The mean tumour size did not change significantly, but the mean percentage of viable tumour decreased significantly from 73.7% before to 29.5% after ablation (P = 0.012, Wilcoxon signed-ranks test). Thermal maps correlated moderately well with follow-up MRI in predicting the extent of tumour ablation (Pearson correlation coefficient 0.55). There were two minor and one major complication.

CONCLUSION

In this pilot study of patients unsuitable for surgery, MRI-guided LTA of renal tumours was safe, feasible (being well tolerated by the patient) and significantly reduced enhancing tumour volume by a mean of 45%.

Minimally invasive image-guided therapies for hepatocellular carcinoma

Minimally invasive therapies are gaining increasing attention as an alternative to standard surgical therapies in the treatment of primary hepatocellular carcinoma. These include therapies administered transcatheterally (arterial embolization, intraarterial chemoinfusion, and combination chemoembolization) and percutaneously (chemical ablation with ethanol or acetic acid, and thermal ablation with radiofrequency, microwave, or laser energies). Benefits over surgical resection include the anticipated reduction in morbidity and mortality, low cost, suitability for real time image guidance, the ability to perform ablative procedures on outpatients, and the potential application in a wider spectrum of patients, including nonsurgical candidates. This review examines reported clinical success, potential complications, current limitations, and future directions of development of chemoembolization, ethanol and acetic acid instillation, and radiofrequency, microwave, and laser thermal ablation.

Femur: MR imaging-guided radio-frequency ablation in a porcine model-feasibility study

PURPOSE

To determine the feasibility of magnetic resonance (MR) imaging-guided and -monitored radio-frequency (RF) ablation of bone.

MATERIALS AND METHODS

Seven femurs were treated in five pigs with use of a 0.2-T open MR imager. An 11-gauge bone marrow needle was percutaneously inserted into the distal femur metaphysis with MR fluoroscopy (fast imaging with steady-state precession, or FISP, sequences) to introduce an RF electrode into the bone with further image guidance. Thermal ablation was performed for 10 minutes (90 degrees C +/- 2 [mean +/- SD]). MR follow-up was performed immediately after ablation and again at 7 and 14 days after the procedure (with contrast material-enhanced T1-weighted, T2-weighted, and fast short inversion time inversion-recovery, or STIR, sequences). The animals were sacrificed at day 14. The femurs were sliced, decalcified, and stained. Image analysis was performed to measure lesion diameter and contrast-to-noise ratio (CNR) and to evaluate complications.

RESULTS

Technical success was obtained in all animals. The lesion diameter perpendicular to the electrode was 15.4 mm +/- 2.7. No significant complications were noted. The thermal lesions displayed low signal intensity with a sharp rim of high signal intensity. T2-weighted images demonstrated the highest CNR and the lowest error in predicting the lesion size immediately after ablation (2.7 mm +/- 1.3). Contrast-enhanced T1-weighted images demonstrated the highest accuracy at day 14 (1.0 mm +/- 1.0).

CONCLUSION

RF ablation of bone with MR imaging as the sole imaging modality is feasible and allows monitoring of the ablation.

Laser therapy for small breast cancers

BACKGROUND

Widespread mammography has resulted in the increased detection of breast cancer <1.5 cm. It may be possible to treat these small tumors with in-situ laser ablation. Prior to ablation tumor size is determined by ultrasound and mammogram. Histologic diagnosis and determination of prognostic factors are obtained from image-guided needle core samples. Invasive and in-situ tumors may be percutaneously ablated by a stereotactically guided laser needle and subsequently evaluated by imaging methods and needle biopsy.

METHODS

Fifty-four patients (50 invasive, 4 in-situ); 51 mass, 3 microcalcification; mean diameter 12 (5 to 23) mm were treated by a stereotactically guided 805 nm laser beam via a fiber in a 16G needle delivered to the cancer. One to 8 weeks later the coagulated lesions were surgically removed for pathologic evaluation. In 2 additional patients, the laser-treated tumors were not removed but were monitored by mammography, ultrasonography, and needle core biopsy.

RESULTS

None of the patients sustained any adverse effect. The average treatment time was 30 minutes. Pathology analysis revealed a 2.5 to 3.5 hemorrhagic ring surrounding the necrotic tumor. Under steady conditions, in two groups of 14 patients, 93% and 100% of the tumors showed complete destruction, with no residual cancer report. In the 2 unresected cases kept under surveillance for 6 to 24 months, the laser-treated tumors first showed shrinkage, followed by a 2 to 3 cm oil cyst. Fibrosis was demonstrated on needle core biopsies.

CONCLUSIONS

Laser energy delivered through a stereotactically guided needle appears to ablate mammographically detected breast cancer. A multicenter clinical trail is planned.

Thermal ablation therapy for hepatocellular carcinoma

Thermal ablation strategies, including the use of radiofrequency, microwaves, lasers, and high-intensity focused ultrasound, are gaining increasing attention as an alternative to standard surgical therapies in the treatment of primary hepatocellular carcinoma. Benefits over surgical resection include the anticipated reduction in morbidity and mortality, low cost, suitability for real-time imaging guidance, ability to perform ablative procedures on an outpatient basis, and the potential application in a wider spectrum of patients-including those who are not surgical candidates. In this review, the authors examine the reported clinical success of each of these four therapies, potential complications, current limitations, and future directions of development.

Radiofrequency ablation of hepatic tumors

Radiofrequency thermal ablation is receiving increasing attention as an alternative to standard surgical therapies for the treatment of liver neoplasms. Benefits over surgical resection include the anticipated reduction in morbidity and mortality, low cost, suitability for real time image guidance, the ability to perform ablative procedures on outpatients, and the potential application in a wider spectrum of patients, including nonsurgical candidates. This review examines reported clinical results of this new therapeutic technique, potential complications, current limitations, thermal ablation mechanisms, as well as technical features and diagnostic modalities used in the procedure.

Laser interstitial thermotherapy (LITT) monitoring using high-resolution digital mammography: theory and experimental studies

Laser interstitial thermotherapy (LITT) is a minimally-invasive laser hyperthermia procedure for the treatment of localized tumours. Real-time monitoring of LITT is essential to control the extent of tumour destruction and ensure safe and effective treatments. The feasibility of using high-resolution digital x-ray mammography to monitor LITT of breast cancer was evaluated. Tissue phantoms including polyacrylamide hydrogel and cadaver porcine tissue were heated using a 980 nm diode laser delivered through optical fibres with diffusing tips. Digital images of the tissue phantoms were recorded with a high-resolution digital stereotactic breast biopsy system during heating. The recorded images were processed and analysed to detect heat-induced changes. No changes were detected during heating of the hydrogel. Pixel-by-pixel subtraction of the initial image from images taken during laser heating shows observable thermally-induced changes around the fibre during laser irradiation that correlate with the thermal denaturation zone observed by gross anatomy. These experiments demonstrate that high-resolution digital x-ray mammography can be used to detect heat-induced tissue changes during experimental LITT in fibro-fatty tissue.

Electrolytic ablation as an adjunct to liver resection: Safety and efficacy in patients

BACKGROUND

Electrolytic ablation is a relatively new method for the local destruction of colorectal liver metastases. Experimental work in animal models has shown this method to be safe and efficacious. However, before proceeding to clinical trials it was necessary to confirm these findings in a pilot study of five patients.

METHODS

Five patients with colorectal liver metastases were studied prospectively. Each patient underwent a potentially curative liver resection. One of the metastases to be removed was treated using electrolysis before resection. Each patient was monitored closely during and after electrolysis to determine any morbidity associated with the treatment. Once resected, the metastases were examined histologically for completeness of ablation.

RESULTS

All patients tolerated the electrolysis well; there were no deaths or complications related to the treatment. Histological examination of the resected metastases which had been treated electrolytically showed complete tissue destruction with no viable malignant cells remaining at the site of treatment.

DISCUSSION

This pilot study of electrolytic ablation of liver metastases in five patients showed the treatment to be well tolerated and safe. Additionally, it demonstrated total destruction of the malignant tissue at the site of electrolysis. Based on these encouraging results, clinical trials can now begin.

Optical properties of selected native and coagulated human brain tissues in vitro in the visible and near infrared spectral range

Medical laser applications require knowledge about the optical properties of target tissue. In this study, the optical properties of selected native and coagulated human brain structures were determined in vitro in the spectral range between 360 and 1100 nm. The tissues investigated included white brain matter, grey brain matter, cerebellum and brainstem tissues (pons, thalamus). In addition, the optical properties of two human tumours (meningioma, astrocytoma WHO grade II) were determined. Diffuse reflectance, total transmittance and collimated transmittance of the samples were measured using an integrating-sphere technique. From these experimental data, the absorption coefficients, the scattering coefficients and the anisotropy factors of the samples were determined employing an inverse Monte Carlo technique. The tissues investigated differed from each other predominantly in their scattering properties. Thermal coagulation reduced the optical penetration depth substantially. The highest penetration depths for all tissues investigated were found in the wavelength range between 1000 and 1100 nm. A comparison with data from the literature revealed the importance of the employed tissue preparation technique and the impact of the theoretical model used to extract the optical coefficients from the measured quantities.

Intraoperative magnetic resonance: the future of surgery

Intraoperative magnetic resonance imaging (iMRI) is a new development in medicine that bridges the specialties of surgery and radiology. Deficiencies in the visualization of anatomical architecture and the perception of tumour boundaries in conventional open surgery have led to the integration of imaging within surgery. The superior soft tissue and multiplanar imaging features of magnetic resonance (MR) make this imaging modality superior to that of alternatives. The unique properties of MR to detect heat change and perfusion, and diffusion characteristics of tissue enhance the usefulness of this medium. Concurrent developments in computer aided image guidance and thermoablative technology, herald the era of minimally invasive tumour ablation. Applications have been developed for areas such as neurosurgery, general surgery, gynaecology and urology.

Treatment of hepatocellular carcinoma with radiofrequency ablation: radiologic-histologic correlation during follow-up periods

To determine whether radiographic images after radiofrequency (RF)-induced coagulation necrosis are correlated with the pathologic effects, we evaluated the morphology and histologic characteristics of RF ablation lesions over a 6-month follow-up period and compared the results with those of radiologic studies. Thirty-three hepatocellular carcinoma (HCC) tumors with a maximum diameter of 3 cm or less were treated percutaneously by using RF ablation in 26 patients. Six treated tumors were resected 4 weeks after ablation; the remaining 27 treated tumors underwent a biopsy procedure by using an 18-gauge fine needle 3 days, 4 weeks, and 24 weeks after ablation. The excised or biopsied lesions were examined by using histologic methods; the findings were then compared with those of contrast-enhanced computed tomography (CT). Three days after ablation, a core of hypoattenuation surrounded by an enhanced/hemorrhagic rim was observed on the contrast-enhanced CT images. Hematoxylin-eosin-stained specimens were inconclusive as to whether or not cellular viability remained; however, cell viability as determined by the presence of histochemical (lactate-dehydrogenase, maleate-dehydrogenase, and the reduced form of nicotinamide-adenine dinucleotide phosphate [NADPH]-diaphorase) stains was absent, suggesting 100% cellular destruction in the ablated lesion. Four and 24 weeks after ablation, the sizes of the ablated lesions were progressively smaller on the CT images; the histochemical stains remained superior to the hematoxylin-eosin stains for obtaining a definite diagnosis of cell death. We conclude that irreversible cellular destruction, as determined by the absence of positive histochemical staining patterns, was useful for evaluating the pathologic thermal effect of RF ablation. These pathologic findings can be correlated with those of contrast-enhanced CT.

Electrolytic ablation as an adjunct to liver resection: experimental studies of predictability and safety

BACKGROUND

Combined liver resection and local ablation may offer the only chance of cure to patients with liver metastases who are presently deemed unresectable because of a single awkwardly placed metastasis. By definition, such a metastasis is often close to a major vein. An ablative technique is needed that is both predictable and safe in such a circumstance.

METHODS

Electrolytic liver lesions were created in 21 pigs using platinum electrodes, connected to a direct current generator. Both electrolytic 'dose' and electrode separation were varied to produce different sized lesions. The 'dose' was correlated with the volume of necrosis and any vascular damage was determined histologically.

RESULTS

There was a significant (P < 0.001) correlation between the electrolytic 'dose' and the volume of liver necrosis. For a given 'dose' the volume of necrosis was less when the electrodes were together, rather than separated. Liver enzymes were only transiently deranged. There were no significant vascular injuries.

CONCLUSION

Predictable and reproducible necrosis is produced by electrolysis in the pig liver. The treatment appears to cause little or no damage to immediately adjacent liver or major vascular structures and, when combined with resection, may offer the chance of a cure to many patients who are currently unresectable.

Small hepatocellular carcinoma: comparison of radio-frequency ablation and percutaneous microwave coagulation therapy

PURPOSE

To evaluate the effectiveness of radio-frequency (RF) ablation and percutaneous microwave coagulation (PMC) for treatment of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Seventy-two patients with 94 HCC nodules were randomly assigned to RF ablation and PMC groups. Thirty-six patients with 48 nodules were treated with RF ablation, and 36 patients with 46 nodules were treated with PMC. Therapeutic effect, residual foci of untreated disease, and complications of RF ablation and PMC were prospectively evaluated with statistical analyses.

RESULTS

The number of treatment sessions per nodule was significantly lower in the RF ablation group than in the PMC group (1.1 vs 2.4; P <.001). Complete therapeutic effect was achieved in 46 (96%) of 48 nodules treated with RF ablation and in 41 (89%) of 46 nodules treated with PMC (P =.26). Major complications occurred in one patient treated with RF ablation and in four patients treated with PMC (P =.36). During follow-up (range, 6-27 months), residual foci of untreated disease were seen in four of 48 nodules treated with RF ablation and in eight of 46 nodules treated with PMC. No significant difference in rates of residual foci of untreated disease was noted (P =.20, log-rank test).

CONCLUSION

RF ablation and PMC thus far have had equivalent therapeutic effects, complication rates, and rates of residual foci of untreated disease. However, RF tumor ablation can be achieved with fewer sessions.

Hepatic tumors treated with percutaneous radio-frequency ablation: CT and MR imaging follow-up

PURPOSE

To describe the appearance of hepatic tumors treated with radio-frequency (RF) ablation on computed tomographic (CT) and magnetic resonance (MR) images and the pattern of residual tumor at the site of RF ablation and to assess prospectively the sensitivity, specificity, and positive and negative predictive CT and MR imaging values in the evaluation of RF treatment.

MATERIALS AND METHODS

Thirty-one patients with 50 tumors (nine hepatocellular carcinomas and 41 metastases) treated with RF ablation underwent CT and MR imaging on the same day at 2, 4, and 6 months; CT was performed every 3 months thereafter. CT and MR findings were interpreted separately and prospectively by two reviewers with consensus. For both imaging techniques, appearance of the treated area, treatment efficacy, and complications were assessed at each time. Sensitivity and specificity were determined by using the McNemar test.

RESULTS

After a mean follow-up of 19 months, nine tumors showed local regrowth. At 2 months, MR imaging depicted more local regrowths (eight of nine; sensitivity, 89%) than did CT (four of nine; sensitivity, 44%) but without significant differences (P =.12). In two cases, only T2-weighted imaging depicted local regrowth. All nine lesions became conspicuous at 4-month follow-up with both techniques. At 2 months, thin peripheral rim enhancement and arterioportal shunting were found in 24% and 12%, respectively, of the treated tumors. These findings disappeared thereafter and are not linked to tumor regrowth.

CONCLUSION

Despite the small number of patients, CT and MR imaging may depicted all local regrowth at 4 months or sooner. MR imaging may have an edge over CT in the early detection of local regrowth.

Influence of the bridging effect by sequential laser application on tissue ablation in an ex vivo model, taking organ perfusion into account

OBJECTIVE

To improve the efficacy of interstitial laser coagulation of tissue by causing a 'bridging' effect, using a sequential multiple-probe procedure on an ex vivo kidney model, as only a limited area of tissue is destroyed with a single probe and the coagulation takes longer when multiple punctures are used.

MATERIALS AND METHODS

A laser beam was generated using a Nd:YAG laser and applied to kidney tissue by a diffuser tip (quartz glass cap 2 x 19 mm). For sequential laser application (SLA), three probes were placed through punctures into kidney tissue, at 5 or 10 mm apart. The laser energy was applied in different time-energy combinations through the three probes. The effect of SLA was compared with that from one probe delivering the optimal PowerMode 180 protocol (Dornier, Germering, Germany), which represents the standard energy protocol for the clinical treatment of parenchymal organs using this laser device. An isolated porcine kidney was chosen for laser coagulation under different conditions of perfusion. The ablative efficacy was defined as the volume of necrosis per minute.

RESULTS

Applying various time-energy combinations to isolated unperfused porcine kidney caused extensive tissue ablation (5.6 mL). In trials with saline and blood perfusion for improved cooling, the necrotic volume was 2.5 and 3.9 mL, respectively (with no carbonization, 3.2 mL). Compared with a single-probe procedure, the ablation efficacy was 10 times better with SLA coagulation. This improvement was initiated by the bridging effect: coagulation in neighbouring areas affects perfusion and convection to an extent that induces the formation of bridges of necrosis between the probes.

CONCLUSION

Tissue ablation is markedly improved by interstitial laser coagulation using a sequential multiple-probe technique.

Percutaneous radiofrequency ablation of hepatic tumors during temporary venous occlusion

OBJECTIVE

We evaluated the feasibility, tolerance, and efficacy of percutaneous hepatic vein or segmental portal branch balloon occlusion during radiofrequency ablation of hepatic malignancies.

SUBJECTS AND METHODS

Ten tumors were treated by percutaneous radiofrequency ablation during balloon occlusion of a hepatic vein (n = 8) or a segmental portal branch (n = 2). Venous occlusion was undertaken because the tumor was in contact with a hepatic vein (n = 3) or a portal branch (n = 1); because the tumor exceeded 35 mm in width (mean, 44 mm), which was considered the maximum size amenable to ablation in a single session (n = 2); or because of both large size and contact with a hepatic vein (n = 3) or a portal branch (n = 1).

RESULTS

Vascular occlusion was always technically possible. Radiofrequency was delivered to one to three locations (mean, 1.9 locations) with a cluster electrode. The largest axis of radiofrequency-induced lesions after ablation with the cluster needle-between 42 and 51 mm (mean, 49 mm)-was always larger than the targeted tumor. These sizes were statistically larger than in a matched control group of patients who underwent radiofrequency ablation without vascular occlusion (p < 0.0003). After a mean follow-up of 12.6 months, CT and MR imaging revealed complete destruction of nine tumors after a single radiofrequency ablation treatment; one tumor required three treatments to achieve ablation. Five patients are tumor-free 12-18 months (mean, 14.4 months) after the first radiofrequency ablation treatment, and five developed new liver metastases.

CONCLUSION

Temporary hepatic vein or portal branch occlusion during radiofrequency ablation can safely facilitate the treatment of large tumors or tumors in contact with the walls of large vessels.

Laser thermal ablation in the treatment of small hepatocellular carcinoma: results in 74 patients

PURPOSE

To evaluate the safety, local effectiveness, and long-term results of laser thermal ablation (LTA) in the treatment of small hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Ninety-two biopsies proved small HCCs (range, 0.8-4.0 cm) in 74 patients who were treated percutaneously with LTA in an outpatient clinic. A laser at a power of 5.0 W was coupled with one to four fibers that were advanced through 21-gauge needle(s) for 6-12 minutes. All lesions were evaluated with computed tomography (CT) for changes in size and vascular pattern, recurrence rates, and cumulative survival rates. Patients were examined for complications.

RESULTS

No major complications occurred in 117 LTA sessions, with an average of 1.3 sessions per tumor. At 3 months, CT scans showed a nonenhancing area (complete necrosis) in 89 (97%) of 92 lesions. During follow-up (range, 6-66 months; mean, 25.3 months), 84 tumors (91%) decreased in size. The local recurrence rates (range, 1-5 years) ranged from 1.6% to 6.0%. Recurrence rates (range, 12-60 months) in other liver segments ranged from 24% to 73%. Cancer-free survival rates (range, 1-4 years) ranged from 73% to 24%. Overall survival rates were 99%, 68%, and 15% at 1, 3, and 5 years, respectively. Twenty-one patients (28%) died.

CONCLUSION

LTA is a safe and effective treatment for small HCC.

Hepatocellular carcinoma after radiofrequency ablation therapy: dynamic CT evaluation of treatment

The aim of this study is to analyze the dynamic CT findings after radiofrequency (RF) ablation for hypervascular hepatocellular carcinoma (HCC). RF ablation was used for 22 tumors in 20 patients. Peripheral enhancement was noted in 89% of regions within 1 month in the arterial phase. In 1-3 months, peripheral enhancement remained at 56% and was reduced to 22% by 3-6 months. It is difficult to determine the therapeutic result within 3 months due to continued peripheral enhancement in the arterial phase.

Image-guided surgery of small breast cancers

BACKGROUND

Widespread screening mammography has resulted in detection of many breast cancers smaller than one cm. Image-guided percutaneous needle sampling provides accurate diagnostic and prognostic information for adjuvant therapy. Less invasive methods based on imaging techniques are emerging as an alternative to wire localization and lumpectomy.

DATA SOURCES

Information presented in this overview was provided by seven investigators from five medical centers in the United States. These researchers are currently developing various techniques of image-guided percutaneous therapy of small (Tis, 1) breast cancers.

CONCLUSIONS

Several percutaneous treatment modalities for treatment of early breast cancer, either excisional or in-situ ablative, are described in this overview and their potential applications are discussed.

Pathologic changes after interstitial laser therapy of infiltrating breast carcinoma

BACKGROUND

Interstitial laser therapy (ILT) is a technique of destroying tumor cells via thermal energy. Prior studies have shown that the procedure is safe and efficacious in laboratory animals and that complete cell death, as assessed by tetrazolium staining, is achieved in the laser treated area.

DESIGN

Forty women with localized, mammographically detectable, T1 breast cancers consented to be treated with ILT and then have the treated area subsequently excised. The delay period ranged from 5 to 42 days. Prior to ILT, the diagnosis of breast carcinoma was established by stereotactic needle core biopsy.

RESULTS

All 40 cases showed a characteristic gross appearance, which consisted of a series of concentric rings surrounding a cavity corresponding to the laser needle tip. The tissue immediately adjacent to the cavity appeared coagulated and showed the same "wind-swept" nuclei seen with cautery artifact. Surrounding this was a white-tan ring that histologically showed recognizable tumor. No necrosis, increased apoptosis or inflammatory infiltrate was noted in this area on hematoxylin-eosin sections. Immunostains for cytokeratin were negative in the recognizable tumor cells despite intense staining in the epithelial cells outside the laser treated area. A ring of red tan tissue which histologically consisted of necrotic tumor was seen next and this, in turn, was surrounded by a rim of vascular proliferation and fat necrosis. The breast tissue outside the zone of fat necrosis appeared to be unaffected by the laser therapy.

CONCLUSIONS

ILT appears to be an effective way to treat small localized breast cancer. It is important for the pathologist to recognize the changes seen after ILT, especially the zone containing pseudoviable tumor. Cytokeratin may be a marker to identify these likely non-viable but recognizable tumor cells. The extent of the laser affected area is defined by vascular proliferation and fat necrosis.

Radio-frequency ablation of liver tumors: assessment of therapeutic response and complications

An alternative to surgical resection of liver tumors, radio-frequency ablation induces in situ thermal coagulation necrosis through the delivery of high-frequency alternating current to the tissues. Imaging helps to detect treatable lesions, guide the placement of the probe, and assess the effect of therapy. Computed tomography (CT) is used most frequently to determine whether the ablation is complete and to screen for early recurrences that may benefit from reablation. Complete ablation creates an area of necrosis that, at CT, is of low attenuation compared with the surrounding liver tissue, is often homogeneous, and has smooth margins. The most important features are the size of the necrotic defect, which, immediately after treatment, should be larger than that of the pretreatment tumor, and the sharpness of the margins, which indicates an abrupt change in attenuation between the necrotic tissue and surrounding liver tissue. Enhancement, when present, is due to perfusion abnormality or granulation tissue and forms a regular rim or a homogeneous zone at the margin of the defect. It is seen immediately after ablation but may be prolonged. Enhancement is affected by the scanning technique. Over time, the size of the defect remains stable or decreases. Any variation from this general pattern is suggestive of incomplete ablation or recurrence.

New nonsurgical therapies in the treatment of hepatocellular carcinoma

The last decade has seen a rapid increase in the incidence of hepatocellular carcinoma in the United States, mostly because of the increased incidence of hepatitis C. Surgical therapy remains limited to the few patients who are surgical candidates at presentation. In addition, surgery has been plagued by high recurrence rates, which can reach 80% at 3 years. Systemic chemotherapy has been found to be ineffective, with response rates approaching 10% to 20%. Nonsurgical percutaneous therapies, including percutaneous locoregional ablative procedures (ethanol or acetic acid injection, radiofrequency ablation, microwave coagulation therapy, chemotherapy infusion, laser photocoagulation, and high-intensity ultrasound) and intra-arterial procedures (radioembolization with yttrium-90 microspheres or transcatheter intra-arterial chemoembolization) are gaining popularity because they are less invasive than surgery and can be nearly as effective in prolonging survival. Multiple studies have shown good response rates with high technical success rates, as well as significant survival advantages for nonresectable disease. Furthermore, they can be performed repeatedly without compromising liver function and at a considerably lower morbidity and cost than surgery.

Hepatocellular carcinoma treated with radiofrequency ablation: comparison of pulse inversion contrast-enhanced harmonic sonography, contrast-enhanced power Doppler sonography, and helical CT

OBJECTIVE

The purpose of this study was to compare the efficacy of contrast-enhanced pulse inversion harmonic imaging with contrast-enhanced power Doppler sonography and helical CT to determine incomplete local treatment after radiofrequency ablation in patients with hepatocellular carcinoma.

MATERIALS AND METHODS

Thirty-five consecutive patients (24 men and 11 women; mean age, 64 years) with 43 hepatocellular carcinomas (3.6 +/- 1.1 cm) were treated using internally cooled radiofrequency ablation therapy. Therapeutic response was evaluated at 4 months with dual-phase contrast-enhanced helical CT, conventional power Doppler Sonography, and pulse inversion harmonic imaging using a sonographic contrast agent (SH-508). CT and sonographic studies were reviewed separately in random order by four radiologists at different consensus conferences. Sensitivity and specificity of the sonographic methods were determined using CT as a gold standard and results were compared using the McNemar test.

RESULTS

CT examinations identified residual tumor in 12 lesions (27.9%). Although conventional contrast-enhanced power Doppler sonography identified residual viable tumor foci in four incompletely treated lesions (9.3%), contrast-enhanced pulse inversion harmonic imaging identified residual tumoral enhancement in 10 lesions (23.3%). Thus, the sensitivity of pulse inversion harmonic imaging (83.3%) was significantly greater (p < 0.05) for detecting residual nonablated tumor compared with conventional contrast-enhanced power Doppler sonography.

CONCLUSION

Our study suggests that contrast-enhanced pulse inversion harmonic imaging may enable the detection of residual nonablated tumor in more cases than contrast-enhanced power Doppler sonography and may ultimately prove to be a useful adjunct for percutaneous ablation therapies. Nevertheless, contrast-enhanced axial imaging (CT or MR imaging) is currently the most sensitive test for managing thermal ablation for patients with hepatocellular carcinoma.

Tumor recurrence after radiofrequency thermal ablation of hepatic tumors: spectrum of findings on dual-phase contrast-enhanced CT

OBJECTIVE

We conducted this study to determine the spectrum of CT findings of tumor recurrence after radiofrequency ablation of primary and secondary malignant hepatic tumors.

MATERIALS AND METHODS

Twenty-five patients, 10 with hepatocellular carcinoma (HCC) and 15 patients with metastases who developed tumor recurrence after radiofrequency ablation of hepatic neoplasms, formed the study population. Three observers reviewed the CT scans of these patients and evaluated the location (local intrahepatic, remote intrahepatic, or extrahepatic) of all recurrent lesions and the morphology and enhancement characteristics of local intrahepatic recurrences.

RESULTS

Local intrahepatic recurrences were seen in nine patients (90%) and 11 patients (73%); remote intrahepatic recurrences, in five patients (50%) and seven patients (45%); and extrahepatic recurrences, in zero and six patients (40%) with recurrent HCC and recurrent metastases, respectively. Of the 12 nodules of local intrahepatic recurrences in HCC and the 24 in metastases, the patterns of local intrahepatic recurrences were of nodular, halo, and gross enlargement types in eight (67%) and nine (38%), four (33%) and six (38%), and zero and nine (37%) nodules in HCC and hepatic metastases, respectively. The number of local intrahepatic recurrent lesions enhancing in the arterial phase was significantly greater in HCC.

CONCLUSION

Tumor recurrences occurred at intra- and extrahepatic sites after radiofrequency ablation of hepatic neoplasms. The local intrahepatic recurrences appeared in three patterns: nodular, halo, or gross enlargement. The sites of recurrence and the morphologic patterns of local intrahepatic tumor recurrence differed between primary and secondary hepatic neoplasms.

Metabolic activity and DNA integrity in human hepatic metastases after interstitial laser coagulation (ILC)

BACKGROUND AND OBJECTIVE

For investigations into interstitial laser coagulation (ILC) of solid tumors, tissue whitening is used as a parameter for the extent of coagulation. This obvious demarcation is associated with global thermal denaturation, but it is not clear whether this finding is a good indicator of the exact outer boundary of the lethal tissue effect.

STUDY DESIGN/MATERIALS AND METHODS

ILC with portal inflow occlusion was performed in human hepatic metastases of colorectal carcinoma directly after surgical resection (n = 5) or before surgical resection (n = 5) with laser parameters adapted to tumor diameter. Mitochondrial NADH-diaphorase activity and DNA integrity were assessed by histoenzymatic staining.

RESULTS

In 7 of 10 tumors (mean diameter, 3.7 cm), an area of macroscopic coagulation (mean diameter, 4.2 cm) encircled the tumor in all three axes. Macroscopic coagulation corresponded to absent metabolism and disintegrated DNA. Furthermore, the macroscopic volumes of coagulation produced in tumor were comparable to the dimensions in normal porcine liver with the same laser parameters.

CONCLUSION

ILC with portal inflow occlusion results in areas with complete cell avitality in the zone of tissue whitening in human hepatic liver metastases.

Laser-induced thermotherapy of malignant liver tumors: general principals, equipment(s), procedure(s)--side effects, complications and results

PURPOSE

To prospectively evaluate the therapeutic potential of MR-guided and ultrasound-guided laser-induced thermotherapy (LITT) in patients with liver metastases and oligonodular hepatocellular carcinoma (HCC).

MATERIAL AND METHODS

Between June 1993 and June 2000 a total of 1608 LITT sessions was performed to treat 1914 lesions in 676 consecutive patients. The Nd-YAG laser fiber was introduced with a percutaneously positioned cooled application set. Qualitative and quantitative ultrasound and magnetic resonance (MR) parameters, as well as clinical data were evaluated.

RESULTS

All patients tolerated the procedure well under local anesthesia; no relevant clinical complications were observed. The mean laser power was 25 W and the mean duration was 25 min. MR proved to be superior over computed tomography and ultrasound due the thermosensitivity of the MR sequences allowing a better visualization of the volume of laser-induced changes and their relation to the neighboring geographical structures. The ultrasound-guided LITT should be restricted for patients with contraindications for MR imaging monitoring and for selected patients with low diameter oligonodular HCC. In 95% of cases, we achieved a complete necrosis of the tumor and a 5-mm safety margin, resulting in a complete destruction of the tumor without local recurrences. Mean survival in this group was 35 months (calculated with the Kaplan-Meier method).

CONCLUSION

MR-guided, or ultrasound-guided, LITT appears to be a safe and effective treatment protocol for liver metastases and oligonodular HCC.