Laser therapy for breast cancer: MR imaging and histopathologic correlation

Ultrasound-Guided Laser Ablation After Excisional Vacuum-Assisted Breast Biopsy for Small Malignant Breast Lesions: Preliminary Results

Background:

The purpose of this preliminary study is to evaluate the feasibility of the excisional ultrasound (US) guided vacuum-assisted breast biopsy (VAE), followed by US-guided Laser Interstitial Thermal Therapy (LITT) in the treatment of unifocal ductal breast carcinomas ≤ 1 cm and estimate the ablation rate analyzing the final histopathological results after subsequent surgical excision.

Methods:

In a single session 11 female patients with unifocal less than a centimeter breast cancer underwent 2 different minimally invasive percutaneous US-guided techniques: a VAE breast biopsy with an 8 G needle to remove the lesion and, immediately after, a LITT ablation in the biopsy site. Four weeks later, all patients underwent radiological follow-up. Afterward, a systematic surgery was performed, the ablation rate was calculated, and iconographic and histological features were correlated.

Results:

Average maximum diameter of the lesions was 7.6 mm (5-10 mm). No patient reported pain or discomfort during procedure. 1/11 patient (9.1%) reported an early minor complication (a small superficial skin burn). After surgical excision, the histopathological evaluation reported in 10/11 cases (90.9%) complete ablation of the target lesion. In only one case (9.1%) residual cancer was detected. The necrotic-hemorrhagic cavities showed a mean maximum diameter of 27.3 mm (20-35 mm).

Conclusions:

Laser ablation performed after excisional biopsy could be considered a valid alternative to surgical excision for the treatment of lesions ≤ 1 cm, if carried out by expert radiologists. The association of these minimally invasive percutaneous methods has proven to be reliable, fast, and safe with an ablation rate of 90.9% and excellent aesthetic results. RM and CESM are potentially able to quantifying treatment results and to follow-up the ablation effects.

T2*-weighted MRI as a non-contrast-enhanced method for assessment of focal laser ablation zone extent in prostate cancer thermotherapy

OBJECTIVES

To evaluate utility of T2*-weighted (T2*W) MRI as a tool for intra-operative identification of ablation zone extent during focal laser ablation (FLA) of prostate cancer (PCa), as compared to the current standard of contrast-enhanced T1-weighted (T1W) MRI.

METHODS

Fourteen patients with biopsy-confirmed low- to intermediate-risk localized PCa received MRI-guided (1.5 T) FLA thermotherapy. Following FLA, axial multiple-TE T2*W images, diffusion-weighted images (DWI), and T2-weighted (T2W) images were acquired. Pre- and post-contrast T1W images were also acquired to assess ablation zone (n = 14) extent, as reference standard. Apparent diffusion coefficient (ADC) maps and subtracted contrast-enhanced T1W (sceT1W) images were calculated. Ablation zone regions of interest (ROIs) were outlined manually on all ablated slices. The contrast-to-noise ratio (CBR) of the ablation site ROI relative to the untreated contralateral prostate tissue was calculated on T2*W images and ADC maps and compared to that in sceT1W images.

RESULTS

CBRs in ablation ROIs on T2*W images (TE = 32, 63 ms) did not differ (p = 0.33, 0.25) from those in sceT1W images. Bland-Altman plots of ROI size and CBR in ablation sites showed good agreement between T2*W (TE = 32, 63 ms) and sceT1W images, with ROI sizes on T2*W (TE = 63 ms) strongly correlated (r = 0.64, p = 0.013) and within 15% of those in sceT1W images.

CONCLUSIONS

In detected ablation zone ROI size and CBR, non-contrast-enhanced T2*W MRI is comparable to contrast-enhanced T1W MRI, presenting as a potential method for intra-procedural monitoring of FLA for PCa.

KEY POINTS

• T2*-weighted MR images with long TE visualize post-procedure focal laser ablation zone comparably to the contrast-enhanced T1-weighted MRI. • T2*-weighted MRI could be used as a plausible method for repeated intra-operative monitoring of thermal ablation zone in prostate cancer, avoiding potential toxicity due to heating of contrast agent.

Photodynamic Therapy in Primary Breast Cancer

Photodynamic therapy (PDT) is a technique for producing localized necrosis with light after prior administration of a photosensitizing agent. This study investigates the nature, safety, and efficacy of PDT for image-guided treatment of primary breast cancer. We performed a phase I/IIa dose escalation study in 12 female patients with a new diagnosis of invasive ductal breast cancer and scheduled to undergo mastectomy as a first treatment. The photosensitizer verteporfin (0.4 mg/kg) was administered intravenously followed by exposure to escalating light doses (20, 30, 40, 50 J; 3 patients per dose) delivered via a laser fiber positioned interstitially under ultrasound guidance. MRI (magnetic resonance imaging) scans were performed prior to and 4 days after PDT. Histological examination of the excised tissue was performed. PDT was well tolerated, with no adverse events. PDT effects were detected by MRI in 7 patients and histology in 8 patients, increasing in extent with the delivered light dose, with good correlation between the 2 modalities. Histologically, there were distinctive features of PDT necrosis, in contrast to spontaneous necrosis. Apoptosis was detected in adjacent normal tissue. Median follow-up of 50 months revealed no adverse effects and outcomes no worse than a comparable control population. This study confirms a potential role for PDT in the management of early breast cancer.

Phase 2 Open-Label Trial Investigating Percutaneous Laser Ablation for Treatment of Early-Stage Breast Cancer: MRI, Pathology, and Outcome Correlations

Background

An institutional review board-approved, multicenter clinical trial was designed to determine the efficacy and outcome of percutaneous laser ablation (PLA) in the treatment of invasive ductal breast carcinoma (IDC). Post-ablation magnetic resonance imaging (MRI) was compared with surgical pathology in evaluation of residual post-ablation IDC and ductal carcinoma in situ.

Methods

Patients with a single focus of IDC 20 mm or smaller by pre-ablation MRI were treated with PLA. The patients underwent a 28-day post-ablation MRI, followed by surgical resection. Cell viability criteria were applied to pre- and post-ablation pathology specimens, which evaluated hematoxylin–eosin (H&E), cytokeratin (CK) 8/18, estrogen receptor, and Ki67 staining patterns.

Results

In this study, 61 patients were reported as the intention-to-treat cohort for determination of PLA efficacy. Of these 61 patients, 51 (84%) had complete tumor ablation confirmed by pathology analysis. One subject’s MRI imaging was not performed per protocol, which left 60 subjects evaluable for MRI pathology correlation. Five patients (8.3%) had residual IDC shown by both MRI and pathology. Post-ablation discordance was noted between MRI and pathology, with four patients (6.7%) false-positive and four patients (6.7%) false-negative. The negative predictive value (NPV) of MRI for all the patients was 92.2% (95% confidence interval [CI], 71.9–91.9%). Of the 47 patients (97.9%) with tumors 15 mm or smaller, 46 were completely ablated, with an MRI NPV of 97.7% (95% CI, 86.2–99.9%).

Conclusions

Percutaneous laser ablation is a potential alternative to surgery for treatment of early-stage IDC. Strong correlations exist between post-ablation MRI and pathologic alterations in CK8/18, ER, and Ki67 staining.

Laser interstitial thermotherapy application for breast surgery: Current situation and new trends

While breast specialists debate on therapeutic de-escalation in breast cancer, the treatment of benign lesions is also discussed in relation to new percutaneous ablation techniques. The purpose of these innovations is to minimize potential morbidity. Laser Interstitial ThermoTherapy (LITT) is an option for the ablation of targeted nodules. This review evaluated the scientific publications investigating the LITT approach in malignant and benign breast disease. Three preclinical studies and eight clinical studies (2 studies including fibroadenomas and 6 studies including breast cancers) were reviewed. Although the feasibility and safety of LITT have been confirmed in a phase I trial, heterogeneous inclusion criteria and methods seem to be the main reason for LITT not being yet an extensively used treatment option. In conclusion, further development is necessary before this technique can be used in daily practice.

Assessment of acute thermal damage volumes in muscle using magnetization-prepared 3D T2 -weighted imaging following MRI-guided high-intensity focused ultrasound therapy

PURPOSE

To evaluate magnetization-prepared 3D T₂ -weighted magnetic resonance imaging (MRI) measurements of acute tissue changes produced during ablative MR high-intensity focused ultrasound (MR-HIFU) exposures.

MATERIALS AND METHODS

A clinical MR-HIFU system (3T) was used to generate thermal lesions (n = 24) in the skeletal muscles of three pigs. T₁ -weighted, 2D T₂ -weighted, and magnetization-prepared 3D T₂ -weighted sequences were acquired before and after therapy to evaluate tissue changes following ablation. Tissues were harvested shortly after imaging, fixed in formalin, and gross-sectioned. Select lesions were processed into whole-mount sections. Lesion dimensions for each imaging sequence (length, width) and for gross sections (diameter of lesion core and rim) were assessed by three physicists. Contrast-to-background ratio between lesions and surrounding muscle was compared.

RESULTS

Lesion dimensions on T₁ and 2D T₂ -weighted imaging sequences were well correlated (R² ∼0.7). The contrast-to-background ratio between lesion and surrounding muscle was 7.4 ± 2.4 for the magnetization-prepared sequence versus 1.7 ± 0.5 for a conventional 2D T₂ -weighted acquisition, and 7.0 ± 2.9 for a contrast-enhanced T₁ -weighted sequence. Compared with diameter measured on gross pathology, all imaging sequences overestimated the lesion core by 22-33%, and underestimated the lesion rim by 6-13%.

CONCLUSION

After MR-HIFU exposures, measurements of the acute thermal damage patterns in muscle using a magnetization-prepared 3D T₂ -weighted imaging sequence correlate with 2D T₂ -weighted and contrast-enhanced T₁ -weighted imaging, and all agree well with histology. The magnetization-prepared sequence offers positive tissue contrast and does not require IV contrast agents, and may provide a noninvasive imaging evaluation of the region of acute thermal injury at multiple times during HIFU procedures.

LEVEL OF EVIDENCE

1 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:354-364.

Technical success, technique efficacy and complications of minimally-invasive imaging-guided percutaneous ablation procedures of breast cancer: A systematic review and meta-analysis

OBJECTIVES

To systematically review studies concerning imaging-guided minimally-invasive breast cancer treatments.

METHODS

An online database search was performed for English-language articles evaluating percutaneous breast cancer ablation. Pooled data and 95% confidence intervals (CIs) were calculated. Technical success, technique efficacy, minor and major complications were analysed, including ablation technique subgroup analysis and effect of tumour size on outcome.

RESULTS

Forty-five studies were analysed, including 1,156 patients and 1,168 lesions. Radiofrequency (n=577; 50%), microwaves (n=78; 7%), laser (n=227; 19%), cryoablation (n=156; 13%) and high-intensity focused ultrasound (HIFU, n=129; 11%) were used. Pooled technical success was 96% (95%CI 94-97%) [laser=98% (95-99%); HIFU=96% (90-98%); radiofrequency=96% (93-97%); cryoablation=95% (90-98%); microwave=93% (81-98%)]. Pooled technique efficacy was 75% (67-81%) [radiofrequency=82% (74-88); cryoablation=75% (51-90); laser=59% (35-79); HIFU=49% (26-74)]. Major complications pooled rate was 6% (4-8). Minor complications pooled rate was 8% (5-13%). Differences between techniques were not significant for technical success (p=0.449), major complications (p=0.181) or minor complications (p=0.762), but significant for technique efficacy (p=0.009). Tumour size did not impact on variables (p>0.142).

CONCLUSIONS

Imaging-guided percutaneous ablation techniques of breast cancer have a high rate of technical success, while technique efficacy remains suboptimal. Complication rates are relatively low.

KEY POINTS

• Imaging-guided ablation techniques for breast cancer are 96% technically successful. • Overall technique efficacy rate is 75% but largely inhomogeneous among studies. • Overall major and minor complication rates are low (6-8%).

Minimally invasive ablative techniques in the treatment of breast cancer: a systematic review and meta-analysis

PURPOSE

Breast-conserving surgery is effective for breast cancer treatment but is associated with morbidity in particular high re-excision rates. We performed a systematic review and meta-analysis to assess the current evidence for clinical outcomes with minimally invasive ablative techniques in the non-surgical treatment of breast cancer.

METHODS

A systematic search of the literature was performed using PubMed and Medline library databases to identify all studies published between 1994 and May 2016. Studies were considered eligible for inclusion if they evaluated the role of ablative techniques in the treatment of breast cancer and included ten patients or more. Studies that failed to fulfil the inclusion criteria were excluded.

RESULTS

We identified 63 studies including 1608 patients whose breast tumours were treated with radiofrequency (RFA), high intensity focussed ultrasound (HIFU), cryo-, laser or microwave ablation. Fifty studies reported on the number of patients with complete ablation as found on histopathology and the highest rate of complete ablation was achieved with RFA (87.1%, 491/564) and microwave ablation (83.2%, 89/107). Short-term complications were most often reported with microwave ablation (14.6%, 21/144). Recurrence was reported in 24 patients (4.2%, 24/570) and most often with laser ablation (10.7%, 11/103). The shortest treatment times were observed with RFA (15.6 ± 5.6 min) and the longest with HIFU (101.5 ± 46.6 min).

CONCLUSION

Minimally invasive ablative techniques are able to successfully induce coagulative necrosis in breast cancer with a low side effect profile. Adequately powered and prospectively conducted cohort trials are required to confirm complete pathological ablation in all patients.

A review of ablative techniques in the treatment of breast fibroadenomata

Introduction

Breast fibroadenomata (FAD) are benign lesions which occur in about 10 % of all women. Diagnosis is made by triple assessment (physical examination, imaging and/or histopathology/cytology). For a definitive diagnosis of FAD, the treatment is conservative unless the patient is symptomatic. For symptomatic patients, the lumps can be surgically excised or removed interventionally by vacuum-assisted mammotomy (VAM). Ablative techniques like high-intensity focused ultrasound (HIFU), cryo-ablation and laser ablation have also been used for the treatment of FAD, providing a minimally invasive treatment without scarring or poor cosmesis. This review summarises current trials using minimally invasive ablative techniques in the treatment of breast FAD.

Methods

A comprehensive review of studies using minimally invasive ablative techniques was performed.

Results

There are currently several trials completed or recruiting patients using HIFU, cryo-ablation and laser ablation in the treatment of breast FAD. The results look very promising but cannot be compared at this point due to heterogeneity between studies.

Conclusion

Minimally invasive ablative techniques like HIFU, cryo-ablation and laser ablation are promising in the treatment of breast FAD. Future trials should be randomised and contain larger numbers of patients to determine the effectiveness of ablative techniques with more precision.

T1 and T2 temperature dependence of female human breast adipose tissue at 1.5 T: groundwork for monitoring thermal therapies in the breast

The T1 and T2 temperature dependence of female breast adipose tissue was investigated at 1.5 T in order to evaluate the applicability of relaxation-based MR thermometry in fat for the monitoring of thermal therapies in the breast. Relaxation times T1 , T2 and T2TSE (the apparent T2 measured using a turbo spin echo readout sequence) were measured in seven fresh adipose breast samples for temperatures from 25 to 65 °C. Spectral water suppression was used to reduce the influence of the residual water signal. The temperature dependence of the relaxation times was characterized. The expected maximum temperature measurement errors based on average calibration lines were calculated. In addition, the heating-cooling reversibility was investigated for two samples. The T1 and T2TSE temperature (T) dependence could be fitted well with an exponential function of 1/T. A linear relationship between T2 and temperature was found. The temperature coefficients (mean ± inter-sample standard deviation) of T1 and T2TSE increased from 25 °C (dT1/dT = 5.35 ± 0.08 ms/°C, dT2TSE/dT = 3.82 ± 0.06 ms/°C) to 65 °C (dT1 /dT = 9.50 ± 0.16 ms/°C, dT2TSE/dT = 7.99 ± 0.38 ms/°C). The temperature coefficient of T2 was 0.90 ± 0.03 ms/°C. The temperature-induced changes in the relaxation times were found to be reversible after heating to 65 °C. Given the small inter-sample variation of the temperature coefficients, relaxation-based MR thermometry appears to be feasible in breast adipose tissue, and may be used as an adjunct to proton resonance frequency shift (PRFS) thermometry in aqueous tissue (glandular + tumor).

Surgical treatment of nonpalpable primary invasive and in situ breast cancer

Breast cancer is the most-common cancer among women worldwide, and over one-third of all cases diagnosed annually are nonpalpable at diagnosis. The increasingly widespread implementation of breast-screening programmes, combined with the use of advanced imaging modalities, such as magnetic resonance imaging (MRI), will further increase the numbers of patients diagnosed with this disease. The current standard management for nonpalpable breast cancer is localized surgical excision combined with axillary staging, using sentinel-lymph-node biopsy in the clinically and radiologically normal axilla. Wire-guided localization (WGL) during mammography is a method that was developed over 40 years ago to enable lesion localization preoperatively; this technique became the standard of care in the absence of a better alternative. Over the past 20 years, however, other technologies have been developed as alternatives to WGL in order to overcome the technical and outcome-related limitations of this technique. This Review discusses the techniques available for the surgical management of nonpalpable breast cancer; we describe their advantages and disadvantages, and highlight future directions for the development of new technologies.

Magnetic Resonance Imaging-Guided Breast Interventions: Role in Biopsy Targeting and Lumpectomies

Contrast-enhanced breast MR imaging is increasingly being used to diagnose breast cancer and to perform biopsy procedures. The American Cancer Society has advised women at high risk for breast cancer to have breast MR imaging screening as an adjunct to screening mammography. This article places special emphasis on biopsy and operative planning involving MR imaging and reviews use of breast MR imaging in monitoring response to neoadjuvant chemotherapy. Described are peer-reviewed data on currently accepted MR imaging-guided procedures for addressing benign and malignant breast diseases, including intraoperative imaging.

Role of ablation in the treatment of breast cancer: A review

Breast cancer surgical treatment has evolved from the days of the radical mastectomy to breast conservation surgery. In recent years, there has been much interest in percutaneous treatment modalities for breast cancer, instead of surgery. There are several different methods of percutaneous treatment of breast cancer. These include cryoablation, radiofrequency ablation, microwave ablation, laser ablation, and ultrasound ablation. The advantages of these techniques include an outpatient or office procedure, with local anaesthesia; minimal scarring, which is only from introducing the percutaneous instrument into the breast, instead of a surgical incision; and minimal recovery time, as the procedure does not involve surgery or general anaesthesia. Disadvantages relate mainly to pathologic evaluation, in that the true size of the breast cancer has to be estimated from the pre-procedure imaging, and all molecular profiling must be obtained from the biopsy specimen. In addition, long term patient satisfaction with cosmesis after adjuvant radiotherapy has not been studied. We review these percutaneous ablation modalities in this paper, as well as their individual techniques, associated advantages, and disadvantages. We also review current clinical trials, exploring these methods of breast cancer treatment.

Magnetic resonance imaging assessment of effective ablated volume following high intensity focused ultrasound

Under magnetic resonance (MR) guidance, high intensity focused ultrasound (HIFU) is capable of precise and accurate delivery of thermal dose to tissues. Given the excellent soft tissue imaging capabilities of MRI, but the lack of data on the correlation of MRI findings to histology following HIFU, we sought to examine tumor response to HIFU ablation to determine whether there was a correlation between histological findings and common MR imaging protocols in the assessment of the extent of thermal damage. Female FVB mice (n = 34), bearing bilateral neu deletion tumors, were unilaterally insonated under MR guidance, with the contralateral tumor as a control. Between one and five spots (focal size 0.5 × 0.5 × 2.5 mm³) were insonated per tumor with each spot receiving approximately 74.2 J of acoustic energy over a period of 7 seconds. Animals were then imaged on a 7T MR scanner with several protocols. T1 weighted images (with and without gadolinium contrast) were collected in addition to a series of T2 weighted and diffusion weighted images (for later reconstruction into T2 and apparent diffusion coefficient maps), immediately following ablation and at 6, 24, and 48 hours post treatment. Animals were sacrificed at each time point and both insonated/treated and contralateral tumors removed and stained for NADH-diaphorase, caspase 3, or with hematoxylin and eosin (H&E). We found the area of non-enhancement on contrast enhanced T1 weighted imaging immediately post ablation correlated with the region of tissue receiving a thermal dose CEM43 ≥ 240 min. Moreover, while both tumor T2 and apparent diffusion coefficient values changed from pre-ablation values, contrast enhanced T1 weighted images appeared to be more senstive to changes in tissue viability following HIFU ablation.

Image-guided ablation in breast cancer treatment

In the past 2 decades, new and improved imaging technologies and the use of breast cancer screening have led to the detection of smaller and earlier-stage breast cancers. Furthermore, there has been a trend toward less aggressive treatment of small breast cancers, which has led to the development of less invasive alternatives than surgery with promising effectiveness, and less morbidity. Many patients are not satisfied with the cosmetic outcome after breast-conservation therapy. Better cosmesis can be achieved with less invasive techniques. Moreover, less aggressive treatment options would be very useful in patients older than 70 years with comorbidities that make surgery a difficult and sometimes life-threatening treatment. Minimally invasive ablation techniques have been studied in early-stage small tumors with the goal of attaining efficacy similar to that of breast-conservation therapy. These techniques would have less scarring and pain, lower costs, better preservation of breast tissue, superior cosmesis, and faster recovery time. Breast lesions can be destroyed by thermal methods, that is, by heating or freezing the tissue. There are 5 types of thermal ablations that have been or currently are in research clinical trials: cryoablation, radiofrequency, laser, microwave, and high-intensity focused ultrasound ablation. The first 4 methods destroy cancers using percutaneous image-guided probe placement. High-intensity focused ultrasound is noninvasive, performed without any skin opening.

Thermal Ablation of Extended Liver Cancers: Assessment of Two New Bipolar Needle Electrodes

In the United States, approximately 155,000 new cases of cancer of the liver and bile duct occur annually. Surgical resection of these tumors is considered the only treatment modality with a curative effect, but only 10% to 15% of patients with liver tumors are considered candidates for surgical resection. For this reason, several alternative treatment modalities have been developed. Radiofrequency energy has been the focus of increasing research and practice over the past few years. Recently, needle electrodes that encompass larger tissue volumes and radiofrequency generators that provide the increased power levels needed to heat these larger tissue volumes have become available. For this pilot study, we were interested in the evaluation of the capacity of larger sized needle electrodes to induce a predictable zone of tissue necrosis within diseased human liver. Furthermore, we wanted to prove safety and effectiveness of radiofrequency ablation in large sized liver tumors. In summary, the use of a bipolar 6 or 8 array electrode and power up to 180–220 watts energy was shown to produce controlled coagulation necrosis of targeted liver parenchyma and tumor with no observed complications.

MR-guided high-intensity focused ultrasound ablation of breast cancer with a dedicated breast platform

Optimizing the treatment of breast cancer remains a major topic of interest. In current clinical practice, breast-conserving therapy is the standard of care for patients with localized breast cancer. Technological developments have fueled interest in less invasive breast cancer treatment. Magnetic resonance-guided high-intensity focused ultrasound (MR-HIFU) is a completely noninvasive ablation technique. Focused beams of ultrasound are used for ablation of the target lesion without disrupting the skin and subcutaneous tissues in the beam path. MRI is an excellent imaging method for tumor targeting, treatment monitoring, and evaluation of treatment results. The combination of HIFU and MR imaging offers an opportunity for image-guided ablation of breast cancer. Previous studies of MR-HIFU in breast cancer patients reported a limited efficacy, which hampered the clinical translation of this technique. These prior studies were performed without an MR-HIFU system specifically developed for breast cancer treatment. In this article, a novel and dedicated MR-HIFU breast platform is presented. This system has been designed for safe and effective MR-HIFU ablation of breast cancer. Furthermore, both clinical and technical challenges are discussed, which have to be solved before MR-HIFU ablation of breast cancer can be implemented in routine clinical practice.

Laser interstitial thermotherapy of small breast fibroadenomas: numerical simulations

BACKGROUND

Laser interstitial thermotherapy (LITT) is potentially a novel method to treat small breast fibroadenoma, without the need for surgical removal. Dosimetry planning and conformation of the treated area of tumor remain major issues, especially for a moving organ such as the breast. Pre-treatment simulation planning of this therapy is an effective method to predict the final thermal damage. In this study, a mathematical model is elaborated to simulate the heat distribution and the thermal damage.

METHODS

The mathematical model was based on finite element method (FEM) to solve the light distribution, bioheat, and thermal damage equations. Six simulations were performed with the following powers: 5, 6, 7, 8, 9, and 10 W (λ = 980 nm), and for an irradiation time of 125 seconds, with a 50 °C iso-damage temperature. To validate these simulations, six turkey breast samples were irradiated with parameters used for simulations. Volumes of thermal damage were calculated by using formulas: spherical, Elliptical, and Carlsson volumes and compared to the simulated volumes.

RESULTS

Differences between volumes were from 0.01 to 1 cm3. Interpolations between volumes from ex vivo experiments with corresponding powers were established. The relationship between the volume of the thermal damage and the laser power was described by a polynomial equation (R2  = 0.99). The power estimated by the interpolation to obtain 1 cm3 of thermal damage was 7.4 W (922 J) and the maximum corresponding temperature was 90 °C.

CONCLUSION

In this study, a good correlation was established between simulation and ex vivo experiments of LITT for fibroadenoma breast cancer.

MRI-guided ablation of breast cancer: where do we stand today?

The treatment of patients with localized breast cancer has changed considerably over the past few decades. The next challenge is to use image-guided minimally invasive tumor ablation techniques. The fact that MRI is the most accurate imaging modality for visualization and delineation of breast tumor margins in three dimensions and provides MRI-based temperature mapping, makes it particularly applicable for monitoring during minimally invasive ablation techniques. The overall result of the studies performed on MRI-guided minimally invasive tumor ablation studies are varying, with reported total tumor ablation rates ranging between 20% and 100%. Strict selection of patients, consensus on the treatment zone margin and optimization of MR-imaging, should make MRI-guided breast cancer tumor ablation a useful tool in clinical practice.

Minimally-invasive thermal ablation of early-stage breast cancer: a systemic review

BACKGROUND

Minimally-invasive thermal ablation techniques provide an effective approach for local destruction of solid tumor. A novel application is the use for treatment of early-stage breast carcinoma.

METHODS

A broad search was conducted in Pubmed, Embase and the Cochrane databases between January 1990 and December 2009. Clinical results of the relevant articles were collected and analyzed.

RESULTS

The analyzed studies were almost all feasibility or pilot studies using different energy sources, patients, tumor characteristics and ablation settings. They were conducted in research settings for the assessment of technical safety and feasibility, and none of those was used alone in clinical practice. Despite many methodological differences, complete tumor ablation could be achieved in 76-100% of breast cancer patients treated with radiofrequency ablation, 13-76% in laser ablation, 0-8% in microwave ablation, 36-83% in cryoablation, and 20-100% in high-intensity focused ultrasound ablation.

CONCLUSION

Minimally-invasive thermal ablation is a promising new tool for local destruction of small carcinomas of the breast. Large randomized control studies are required to assess the long-term advantages of minimally-invasive thermal ablation techniques compared to the current breast conserving therapies.

Fiber Optic Microneedles for Transdermal Light Delivery: Ex Vivo Porcine Skin Penetration Experiments

Shallow light penetration in tissue has been a technical barrier to the development of light-based methods for in vivo diagnosis and treatment of epithelial carcinomas. This problem can potentially be solved by utilizing minimally invasive probes to deliver light directly to target areas. To develop this solution, fiber optic microneedles capable of delivering light for either imaging or therapy were manufactured by tapering step-index silica-based optical fibers employing a melt-drawing process. Some of the microneedles were manufactured to have sharper tips by changing the heat source during the melt-drawing process. All of the microneedles were individually inserted into ex vivo pig skin samples to demonstrate the feasibility of their application in human tissues. The force on each microneedle was measured during insertion in order to determine the effects of sharper tips on the peak force and the steadiness of the increase in force. Skin penetration experiments showed that sharp fiber optic microneedles that are 3 mm long penetrate through 2 mm of ex vivo pig skin specimens. These sharp microneedles had a minimum average diameter of 73 μm and a maximum tip diameter of 8 μm. Flat microneedles, which had larger tip diameters, required a minimum average diameter of 125 μm in order to penetrate through pig skin samples. Force versus displacement plots showed that a sharp tip on a fiber optic microneedle decreased the skin’s resistance during insertion. Also, the force acting on a sharp microneedle increased more steadily compared with a microneedle with a flat tip. However, many of the sharp microneedles sustained damage during skin penetration. Two designs that did not accrue damage were identified and will provide a basis of more robust microneedles. Developing resilient microneedles with smaller diameters will lead to transformative, novel modes of transdermal imaging and treatment that are less invasive and less painful for the patient.

MRI-guided interventions of the breast

MRI has proven to be a very reliable diagnostic tool in the detection and differential diagnosis of breast lesions. Some lesions are, even in retrospect, not detectable in x-ray or ultrasound images but MRI is able to detect lesions at a much smaller size than the average size of lesions depicted by x-ray and ultrasound. The aim in the future is to develop combined procedures where imaging, biopsy, and interventional therapies are combined in a single outpatient procedure. As a step toward this goal different interventional procedures are useful that include interstitial laser therapy (ILT), radiofrequency ablation (RFA), high-intensity focused ultrasound (HIFU), microwave ablation therapy, and cryotherapy. In this overview the main features and initial results of these procedures are described and discussed.

Minimally invasive ablative therapies for invasive breast carcinomas: an overview of current literature

BACKGROUND

Minimally invasive treatment may be an alternative to breast-conserving surgery.

METHODS

A structured PubMed, Embase, Cochrane, and Web of Science search was performed. Endpoints studied were feasibility, completeness of ablation, timing of the sentinel node biopsy (SNB), imaging modalities, and treatment-related complications.

RESULTS

A total of 24 articles were retrieved, and the level of evidence varied (2B-4). Mainly phase II studies with a treat-and-resect protocol were analyzed. Up to 100% completeness of ablation was reported for radiofrequency ablation (RFA), cryosurgery, and focused ultrasound (FUS). The oncologic results need further evaluation. Dynamic contrast enhanced MRI seems to be the best method for monitoring treatment response (77% sensitivity, 100% specificity). Ultrasound is suitable for guiding probes into the tumor. There is no consensus on the timing of the SNB.

CONCLUSIONS

All studies on minimally invasive ablative modalities published so far show that these techniques are feasible and safe. At this stage only T1 tumors should be ablated in a clinical trial setting; it is unclear which of the modalities is most suitable.

Radiofrequency ablation for breast cancer: A review of the literature

INTRODUCTION

Radiofrequency ablation (RFA) provides an effective technique for minimally invasive tissue destruction. A novel application is the use for treatment of small breast carcinoma.

METHODS

A broad search was conducted in Pubmed, Embase and the Cochrane library. Results of the relevant articles were analysed.

RESULTS

The analysed studies were all feasibility or pilot studies using different patient and tumour characteristics and ablation settings. Despite many methodological differences, high percentages of complete tumour ablation varying between 80% and 100% were reported.

CONCLUSION

Radiofrequency ablation is a promising new tool for minimally invasive ablation of small carcinomas of the breast. A large randomized control study is required to assess the long-term advantages of RFA compared to the current breast conserving therapies.

Ultrasound-guided percutaneous radiofrequency ablation in elderly breast cancer patients: preliminary institutional experience

Breast cancer is a major source of morbidity and mortality in the elderly population and the number of patients will increase by 30% in future decades. Surgery and endocrine therapy could be considered as the standard treatment in elderly breast cancer patients, but anaesthesia for surgery requires a specific approach taking into account physiological and psychological alterations secondary to ageing. In cases with major alterations of performance status, percutaneous radiofrequency ablation (RFA) could be substituted for the surgical treatment. The aim of the current study is to evaluate the efficacy and feasibility of this technique. Five tumours in four consecutive patients (aged 79-82 years) contraindicated for surgery with symptomatic cT1-2N0M0, positive oestrogen receptor status, low grade were treated by percutaneous radiofrequency-lump ablation under local analgesia, using percutaneous ultrasound guidance. Thermal lesions were produced with RF power 30 W, at a frequency of 500 kHz. Ultrasound-guided percutaneous biopsy of the RF treated breast was performed during the follow-up. We report a successful RFA lump ablation experience in the treatment of four tumours (4/5). One local recurrence occurred within 4 months after RFA. The other biopsies taken during the follow up showed all fat necrosis within the oil cyst and no malignant cells. One abscess occurred at 9 months within the treated area. After a mean follow up of 29.4 months, all the patients are still alive without any other signs of recurrence or metastases. Ultrasound-guided percutaneous RFA is safe and feasible in the management of breast cancer in elderly patients. Nevertheless, further large comparative studies are needed in order to validate such a minimally invasive procedure in current practice.

Minimally invasive approaches for diagnosis and treatment of early-stage breast cancer

Breast cancer management has been evolving toward minimally invasive approaches. Image-guided percutaneous biopsy techniques provide accurate histologic diagnosis without the need for surgical biopsy. Breast conservation therapy has become the treatment standard for early-stage breast cancer. Sentinel lymph node biopsy is a new procedure that can predict axillary lymph node status without the need of axillary lymph node dissection. The next challenge is to treat primary tumors without surgery. For this purpose, several new minimally invasive procedures, including radiofrequency ablation, interstitial laser ablation, focused ultrasound ablation, and cryotherapy, are currently under development and may offer effective tumor management and provide treatment options that are psychologically and cosmetically more acceptable to the patients than are traditional surgical therapies. In this review, we give an overview of minimally invasive approaches for the diagnostic and therapeutic management of early-stage breast cancer.

Correlation of contrast-enhanced MR images with the histopathology of minimally invasive thermal and cryoablation cancer treatments in normal dog prostates

Magnetic Resonance Imaging (MRI) is a promising tool for visualizing the delivery of minimally invasive cancer treatments such as high intensity ultrasound (HUS) and cryoablation. We use an acute dog prostate model to correlate lesion histopathology with contrast-enhanced (CE) T1 weighted MR images, to aid the radiologists in real time interpretation of in vivo lesion boundaries and pre-existing lesions. Following thermal or cryo treatments, prostate glands are removed, sliced, stained with the vital dye triphenyl tetrazolium chloride, photographed, fixed and processed in oversized blocks for routine microscopy. Slides are scanned by Trestle Corporation at .32 microns/pixel resolution, the various lesions traced using annotation software, and digital images compared to CE MR images. Histologically, HUS results in discrete lesions characterized by a "heat-fixed" zone, in which glands subjected to the highest temperatures are minimally altered, surrounded by a rim or "transition zone" composed of severely fragmented, necrotic glands, interstitial edema and vascular congestion. The "heat-fixed" zone is non-enhancing on CE MRI while the "transition zone" appears as a bright, enhancing rim. Likewise, the CE MR images for cryo lesions appear similar to thermally induced lesions, yet the histopathology is significantly different. Glands subjected to prolonged freezing appear totally disrupted, coagulated and hemorrhagic, while less intensely frozen glands along the lesion edge are partially fragmented and contain apoptotic cells. In conclusion, thermal and cryo-induced lesions, as well as certain pre-existing lesions (cystic hyperplasia - non-enhancing, chronic prostatitis - enhancing) have particular MRI profiles, useful for treatment and diagnostic purposes.

MRI-Guided percutaneous biopsy of breast lesions: materials, techniques, success rates, and management in patients with suspected radiologic-pathologic mismatch

MR imaging of the breast allows the detection of suspicious breast lesions that are occult at mammography and ultrasound. For the histologic verification of such lesions, percutaneous MR imaging-guided biopsy techniques can now be offered as an alternative to open breast biopsy. This review focuses on the currently available devices and techniques for MR imaging-guided percutaneous breast biopsy and reports their achievable diagnostic accuracy. Technical success rates and strategies for patient management are also outlined. In addition, new developments in MR imaging-guided minimally invasive therapeutic interventions are discussed, as well as the potential for research opportunities and directions.

Breast interventions: a primer for interventional radiologists

Breast cancer is the second leading cause of cancer related deaths in the United States. The area of breast interventions has benefited from recent advances in devices and imaging quality. Ultrasound, MRI, and stereotactic guided vacuum assisted and mechanical rotating stick freeze biopsy are the preferred methods for histologic diagnosis of breast lesions. Ablation techniques are available for the treatment of benign and malignant breast disease. The MammoSite balloon catheter can be placed percutaneously for delivering high dose short term brachytherapy. Interventional Radiologists can and should perform all of these procedures to improve the quality of women's health.

Locoregional therapy of breast cancer: maximizing control, minimizing morbidity

The goal of locoregional therapy in breast cancer has remained unchanged for a century: the eradication of all malignant cells from the breast and draining lymph nodes, hopefully prior to them having spread to distant organs. However, how we accomplish this goal has changed dramatically over this time period and our success in achieving this goal has been greatly enhanced by improvements in breast imaging and systemic therapies. The therapeutic importance of surgery and radiation has been underestimated in recent years and is thought to have minimal impact on long-term outcome. More recent data have reputed this contention and the relationship between local control and survival in breast cancer is becoming increasingly apparent. This article will review the importance of attaining optimum local control with minimum morbidity and examine where the future of locoregional therapy of breast cancer may lie.

Doppler US with perfusion software and contrast medium injection in the early evaluation of radiofrequency in breast cancer recurrences: A prospective phase II study

INTRODUCTION

The aim of this study was to determine the efficacy of Doppler ultrasonography (US) with perfusion software and contrast agent injection (DUPC) during radiofrequency (RF) treatment of local recurrent breast cancer.

MATERIALS AND METHODS

Ten patients were included in this monocentric prospective phase II study. DUPC was performed for each patient the day before treatment and immediately after RF in the operating suite. RF ablation was followed by a total mastectomy. The results of DUPC were compared to the histologic analysis of the operative specimen.

RESULTS

Before RF, contrast uptake exceeded 70% in 5 lesions and was less than 50% in 5 lesions. Immediately after RF, no vascularization was detected with DUPC in 9 of the 10 lesions. Contrast uptake attaining 30% was depicted in the remaining lesion. At histologic analysis, complete tumour destruction was confirmed in 7 of the 10 operative specimens.

CONCLUSION

In this study, DUPC is highly efficient and better adapted for the confirmation of tumour destruction in tumours that are hypervascularised before RF compared to hypovascularised lesions.

Ultrasound-guided, percutaneous cryotherapy of small (< or = 15 mm) breast cancers

RATIONALE AND OBJECTIVE

The purpose of this study was to investigate the feasibility, efficacy, and safety of ultrasound-guided percutaneous cryotherapy of stage T1 breast cancers.

MATERIALS AND METHODS

Thirty patients with biopsy-confirmed breast cancers with tumor diameters of 15 mm or smaller (range, 5-15 mm; median, 12 mm) underwent cryotherapy. After local anesthesia, a 3-mm cryo probe was placed into the tumor under ultrasound guidance. All tumors were subjected to 2 freeze cycles with an interposing thawing cycle. The size of the ice-balls, their distance to the skin, and the temperature at the tip of the probe were closely monitored during the procedure. The patients underwent surgery within 6 weeks and the specimens were evaluated histologically.

RESULTS

The median minimum temperature reached -146 degrees C (range, -117 degrees C to -167 degrees C). In 5 of 29 patients, remnant ductal carcinoma in situ was detectable histologically after cryotherapy beyond the margin of the cryosite in the specimens after open surgery. In 24 patients, no viable tumor cells were found. No severe side effects occurred. In one patient, the cryo procedure was not performed completely because of technical problems.

DISCUSSION

Percutaneous cryotherapy is a feasible and safe procedure in minimally invasive therapy for small breast cancers. Residual ductal carcinoma in situ may be attributable to the beginning of a learning curve or by false-negative detection in pre-interventional imaging. Magnetic resonance mammography might aid in treatment planning and for therapy monitoring to better define target tissue and to correlate the tumor margin with the ice-ball.

MR-Guided Interventions of the Breast

Techniques and instrumentation are now widely available that enable interventional MR-guided preoperative needle localization and lesion marking. Minimally invasive MR-guided core biopsy techniques have been demonstrated but remain limited for small lesions and will be facilitated by the development of biopsy instruments that can be directly visualized using MR imaging. MR-guided tumor ablation is beginning to be evaluated in a few centers. It holds promise as new treatment modality in the continuing trend toward greater breast conservation in the local therapy of breast cancer. Further studies are needed to document the ability of MR-guided ablation to control the margins of a tumor as effectively as surgery. Patients with an extensive in situ intra-ductal component may pose a significant hurdle because the extent of ductal carcinoma in situ maybe underestimated on breast MR images. Ultimately, the success of MR-guided thermal ablation depends on the ability of MR imaging to map the extent of heating during the procedure so that the procedure can be performed to achieve complete control of the tumor margins. It is unfortunate that the conventional method for MR thermometry--the proton resonance frequency shift method--does not work in fat or in voxels with a mix of fat and glandular tissue and, hence, has limited applicability in the breast. Other methods, including measurement of T1 and T2, are being investigated as alternatives.

Cryoablation of benign breast tumors: evolution of technique and technology

We report on improvements in cryoprobe design and techniques of cryoablation as a minimally invasive alternative to open surgery for the treatment of benign breast tumors. In the study, which was conducted in 12 centers, 124 lesions in 102 patients were monitored for a period of 12 months after cryoablation. Two different treatment techniques were used: Double HI FREEZE and Tailored Freeze. In patients treated with the Tailored Freeze technique significantly better results were recorded 12 months after the procedure: the median reduction in tumor volume was 91%, 73% of all tumors treated were nonpalpable, 84% of lesions less than 2.5 cm in maximum diameter were nonpalpable, and none of the 31 mammograms performed yielded abnormal findings. Patient satisfaction was good to excellent in 92% of the patients. The safety profile of this technique was excellent; all complications were minor. Evolution of cryoablation freezing techniques, coupled with improvements in cryoprobe design, has resulted in significant improvements in both safety and effectiveness.

Small (<2.0-cm) Breast Cancers: Mammographic and US Findings at US-guided Cryoablation—Initial Experience

PURPOSE

To determine the mammographic and ultrasonographic (US) findings at cryoablation of small solitary invasive breast cancers and compare them with presence of residual malignancy after treatment.

MATERIALS AND METHODS

Institutional review board approval and informed patient consent were obtained. Nine patients with small solitary invasive breast cancers diagnosed at core biopsy were treated with US-guided cryoablation and a 2.7-mm cryoprobe. Mean cancer size was 12 mm (range, 8-18 mm); four were palpable. Tabletop argon gas-based cryoablation system with a double-freeze-thaw protocol was used to treat cancers in outpatient setting. Tumor sites were excised at lumpectomy 2-3 weeks after cryoablation. Findings at mammography and US before, during, and after cryoablation were assessed to categorize densities and masses on mammograms and masses on US images with Breast Imaging Reporting and Data System (BI-RADS); maximum cancer size was measured. Imaging findings and clinical breast examination data were compared with histologic findings from lumpectomy specimens to determine presence of intraductal or invasive cancer.

RESULTS

With US guidance, ice balls (maximal mean size, 4.4 cm) were formed around cancers. Before excision, eight patients underwent mammography; all had new focal densities (maximum size, 2.5-5.0 cm) at cancer sites. Six patients underwent preexcisional US; 100% of them had new hyperechogenicity in tissue surrounding cancer site. Seven (78%) of nine patients had no residual cancer; specimens contained fat necrosis. One patient had a small focus of invasive cancer; one had extensive multifocal ductal carcinoma in situ. Patients with BI-RADS category 1 or 2 densities on mammograms or nonpalpable tumors had no residual malignancy. No residual invasive cancer occurred in tumors 17 mm or smaller or in cancers without spiculated margins at US.

CONCLUSION

After cryoablation, there was increased echogenicity at US and increased density at mammography; these findings were observed in areas that approximated location and size of the ice ball. Tumor size, mammographic density, and US characteristics may be indicators of likelihood of complete cryoablation.

Cryoablation treatment of benign breast lesions with 12-month follow-up

OBJECTIVE

Eighty percent of all breast biopsies reveal benign findings. The most common benign tumor is a fibroadenoma. Despite their benign nature, many women eventually choose to have their bothersome lumps surgically removed. We report the use of cryoablation to treat these benign breast lesions with minimum 12-month follow-up.

METHODS

After receiving Institutional Review Board approval, a prospective nonrandomized trial was initiated in June 2000. Ultrasound-guided cryoablation of core biopsy-proven benign fibroadenomas, other benign breast nodules, or nodular fibrocystic change was performed on 78 lesions in 63 patients. Eighty-five percent of lesions treated were benign fibroadenomas. The cryoablation procedure consisted of a double freeze-thaw cycle that lasted between 6 and 30 minutes and was performed most often in an office setting. Each patient was serially evaluated for treatment efficacy, complications, and patient satisfaction.

RESULTS

Sixty-four of 78 lesions (mean size 2.0 cm [range 0.8 to 4.2]) were followed-up for at least 12 months after cryoablation per protocol, which included 53 fibroadenomas. At 1 year, ultrasound tumor volume resorption was 88.3% overall (87.3% for fibroadenomas), and 73% of the entire group became nonpalpable to both clinician and patient (75% for fibroadenomas). Two of the fibroadenoma patients had their palpable residual nodule excised, both revealing necrotic debris and no viable tumor in the treated volume. Serial mammograms showed resorption of the lesion leaving minimal residual density without calcifications. Cosmesis was excellent with only a small scar remaining at the probe insertion site. There was no report of visual or palpable volumetric deficit. Patient satisfaction was good to excellent in 92% of cases.

CONCLUSIONS

Cryoablation was successful in treating core biopsy-proven benign breast lesions in 63 patients. At 12 months, we found gradual resorption of treated tissue with no cosmetic deficit. Ultrasound-guided cryoablation is an effective and safe treatment for benign breast lesions, as seen at 12-month follow-up, and offers an office-based, minimally invasive alternative to surgical excision.

Design of an MRI-Compatible Robotic Stereotactic Device for Minimally Invasive Interventions in the Breast†

The objective of this work was to develop a robotic device to perform biopsy and therapeutic interventions in the breast with real-time magnetic resonance imaging (MRI) guidance. The device was designed to allow for (i) stabilization of the breast by compression, (ii) definition of the interventional probe trajectory by setting the height and pitch of a probe insertion apparatus, and (iii) positioning of an interventional probe by setting the depth of insertion. The apparatus is fitted with five computer-controlled degrees of freedom for delivering an interventional procedure. The entire device is constructed of MR compatible materials, i.e. nonmagnetic and non-conductive, to eliminate artifacts and distortion of the MR images. The apparatus is remotely controlled by means of ultrasonic motors and a graphical user interface, providing real-time MR-guided planning and monitoring of the operation. Joint motion measurements found probe placement in less than 50 s and sub-millimeter repeatability of the probe tip for same-direction point-to-point movements. However, backlash in the rotation joint may incur probe tip positional errors of up to 5 mm at a distance of 40 mm from the rotation axis, which may occur for women with large breasts. The imprecision caused by this backlash becomes negligible as the probe tip nears the rotation axis. Real-time MR-guidance will allow the physician to correct this error. Compatibility of the device within the MR environment was successfully tested on a 4 Tesla MR human scanner.

MR imaging–guided breast ablative therapy

The integration of imaging and thermal therapy can provide a minimally invasive or even noninvasive alternative to breast surgery for small tumors. Ongoing trials seek to show safety and efficacy for laser, radiofrequency, microwave, cryoablation, and focused ultrasound surgery. To be successful, these therapies must achieve equivalent or even greater efficacy as surgical outcomes and must demonstrate total ablation of the dominant lesion with negative margins, while sparing normal tissue beyond the target tissue. Procedures have been validated by histopathology subsequent to resection.

Cryoablation of early-stage breast cancer: work-in-progress report of a multi-institutional trial

BACKGROUND

With recent improvements in breast imaging, our ability to identify small breast tumors has markedly improved, prompting significant interest in the use of ablation without surgical excision to treat early-stage breast cancer. We conducted a multi-institutional pilot safety study of cryoablation in the treatment of primary breast carcinomas.

METHODS

Twenty-nine patients with ultrasound-visible primary invasive breast cancer </=2.0 cm were enrolled. Twenty-seven (93%) successfully underwent ultrasound-guided cryoablation with a tabletop argon gas-based cryoablation system with a double freeze/thaw cycle. Standard surgical resection was performed 1 to 4 weeks after cryoablation. Patients were monitored for complications, and pathology data were used to assess efficacy.

RESULTS

Cryoablation was successfully performed in an office-based setting with only local anesthesia. There were no complications to the procedure or postprocedural pain requiring narcotic pain medications. Cryoablation successfully destroyed 100% of cancers <1.0 cm. For tumors between 1.0 and 1.5 cm, this success rate was achieved only in patients with invasive ductal carcinoma without a significant ductal carcinoma-in-situ (DCIS) component. For unselected tumors >1.5 cm, cryoablation was not reliable with this technique. Patients with noncalcified DCIS were the cause of most cryoablation failures.

CONCLUSIONS

Cryoablation is a safe and well-tolerated office-based procedure for the ablation of early-stage breast cancer. At this time, cryoablation should be limited to patients with invasive ductal carcinoma </=1.5 cm and with <25% DCIS in the core biopsy. A multicenter phase II clinical trial is planned.

Office-Based cryoablation of breast fibroadenomas: 12-month followup1 1Funding for this study was provided by Sanarus Medical, Inc

BACKGROUND

Fibroadenomas comprise between 30% and 50% of all breast biopsies. Despite their benign nature, many women have their fibroadenomas surgically removed. We previously reported on a minimally invasive therapy using cryoablation to treat fibroadenomas. We now report on 12-month followup using this technique.

STUDY DESIGN

A prospective, nonrandomized trial was initiated in June 2000 with IRB approval. The Visica Treatment System was used to cryoablate 70 biopsy-proved fibroadenomas in 57 patients using a freeze-thaw-freeze cycle lasting 6 to 30 minutes. Each patient was serially evaluated for safety, efficacy, and satisfaction.

RESULTS

Fifty-seven fibroadenomas (mean 2.1 cm, range 0.8 to 4.2 cm) in 47 patients were followed for 12 months. At 1 year, with 89% median tumor volume reduction measured by ultrasonography, 75% of fibroadenomas were nonpalpable. There were no adverse events and only minor complications. Two patients (4%) had their lesions excised after 12 months; pathology revealed no viable fibroadenoma. Serial mammograms showed resorption of the fibroadenoma leaving minimal residual density without calcifications. Cosmesis was excellent with no volume deficit, as no tissue is removed. Ninety-one percent of patients were satisfied at 12 months.

CONCLUSIONS

Cryoablation is safe and effective in treating breast fibroadenomas. It offers a nonsurgical, office-based treatment that is well tolerated by patients and accurately monitored with ultrasonographic guidance. At 12 months we found progressive tumor volume reduction and reduced palpability, with no volume deficit, excellent cosmesis, and satisfied patients. Ultrasonography-guided cryoablation is a preferred option for treatment of breast fibroadenomas without open surgery.

Thermal analysis of laser interstitial thermotherapy inex vivofibro-fatty tissue using exponential functions

A therapeutic procedure to treat small, surface breast tumours up to 10 mm in radius plus a 5 mm margin of healthy, surrounding tissue using laser interstitial thermotherapy (LITT) is currently being investigated. The purpose of this study is to analyse and model the thermal and coagulative response of ex vivo fibro-fatty tissue, a model for breast tissue, during experimental laser interstitial thermotherapy at 980 nm. Laser radiation at 980 nm was delivered interstitially through a diffusing tip optical fibre inserted into a fibro-fatty tissue model to produce controlled heating at powers ranging from 3.2 to 8.0 W. Tissue temperature was measured with thermocouples placed at 15 positions around the fibre. The induced coagulation zone was measured on gross anatomical sections. Thermal analysis indicates that a finite sum of exponential functions is an approximate solution to the heat conduction equation that more accurately predicts the time-temperature dependence in tissue prior to carbonization (T < 100 degrees C) during LITT than the traditional model using a single exponential function. Analysis of the ellipsoid coagulation volume induced in tissue indicates that the 980 nm wavelength does not penetrate deep enough in fibro-fatty tissue to produce a desired 30 mm diameter (14.1 x 10(3) mm3) coagulation volume without unwanted tissue liquefaction and carbonization.