Heidy Sierra

Confocal Microscopy-Guided Laser Ablation for Superficial and Early Nodular Basal Cell Carcinoma A Promising Surgical Alternative for Superficial Skin Cancers

IMPORTANCE Laser ablation is a rapid and minimally invasive approach for the treatment of superficial skin cancers, but efficacy and reliability vary owing to lack of histologic margin control. High-resolution reflectance confocal microscopy (RCM) may offer a means for examining margins directly on the patient. OBSERVATIONS We report successful elimination of superficial and early nodular basal cell carcinoma (BCC) in 2 cases using RCM imaging to guide Er:YAG laser ablation. Three-dimensional (3D) mapping is feasible with RCM to delineate the lateral border and thickness of the tumor. Thus, the surgeon may deliver laser fluence and passes with localized control-ie, by varying the ablation parameters in sublesional areas with specificity that is governed by the 3D topography of the BCC. We further demonstrate intraoperative detection of residual BCC after initial laser ablation and complete removal of remaining tumor by additional passes. Both RCM imaging and histologic sections confirm the final clearance of BCC. CONCLUSIONS AND RELEVANCE Confocal microscopy may enhance the efficacy and reliability of laser tumor ablation. This report represents a new translational application for RCM imaging, which, when combined with an ablative laser, may one day provide an efficient and cost-effective treatment for BCC.

Confocal microscopy to guide Erbium:yttrium aluminum garnet laser ablation of basal cell carcinoma: an ex vivo feasibility study

Abstract. For the removal of superficial and nodular basal cell carcinomas (BCCs), laser ablation provides certain advantages relative to other treatment modalities. However, efficacy and reliability tend to be variable because tissue is vaporized such that none is available for subsequent histopathological examination for residual BCC (and to confirm complete removal of tumor). Intra-operative reflectance confocal microscopy (RCM) may provide a means to detect residual tumor directly on the patient and guide ablation. However, optimization of ablation parameters will be necessary to control collateral thermal damage and preserve sufficient viability in the underlying layer of tissue, so as to subsequently allow labeling of nuclear morphology with a contrast agent and imaging of residual BCC. We report the results of a preliminary study of two key parameters (fluence, number of passes) vis-à-vis the feasibility of labeling and RCM imaging in human skin ex vivo, following ablation with an erbium:yttrium aluminum garnet laser.

Carbon dioxide laser ablation of basal cell carcinoma with visual guidance by reflectance confocal microscopy: a proof-of-principle pilot study

Laser ablation is an alternative, nonsurgical treatment modality for low‐risk basal cell carcinoma (BCC). However, lack of confirmative tumour destruction or residual tumour presence has been a limiting factor to its adoption. Reflectance confocal microscopy (RCM) provides noninvasive, cellular‐level resolution imaging of the skin and is capable of identifying tumour.

Confocal imaging of carbon dioxide laser-ablated basal cell carcinomas: An ex-vivo study on the uptake of contrast agent and ablation parameters.

Laser ablation can be an effective treatment for the minimally invasive removal of superficial and early nodular basal cell carcinomas (BCCs). However, the lack of histological confirmation after ablation results in high variability of recurrence rates and has been a limitation. Reflectance confocal microscopy (RCM) imaging, combined with a contrast agent, may detect the presence (or absence) of residual BCC tumors directly on the patient and thus provide noninvasive histology‐like feedback to guide ablation. The goal of this ex vivo bench‐top study was to determine affective ablation parameters (fluence, number of passes) for a CO2 laser that will allow both removal of BCCs and control of the underlying thermal coagulation zone in post‐ablated tissue to enable uptake of contrast agent and RCM imaging.

Novel approaches to imaging basal cell carcinoma

The gold standard of diagnosis for nonmelanoma and melanoma skin cancer has been skin biopsy with routine paraffin embedded hematoxylin and eosin histopathology. This practice is frequently carried out on suspicious lesions to rule out a malignant process. Therefore, as a result, many biopsies are done on benign lesions. Unlike other fields of medicine that rely on noninvasive imaging modalities, the use of imaging devices in dermatology has not been as robust. This has been mainly due to the limited resolution offered by imaging devices that is needed to detect malignant changes in the cutaneous layers. However, the demand for more efficient in vivo and ex vivo imaging tools to reduce the amount of biopsies have led to new areas of investigation using noninvasive modalities to augment the clinical diagnosis of skin cancer. The use of noninvasive imaging both in vivo and ex vivo has the potential to increase efficiency of diagnosis and management, decrease healthcare cost, improve clinical care and enhance patient satisfaction.

Induced structural defects in Ti-doped ZnO and its two-photon-excitation

ZnO is a well-known luminescent material that reacts with light to generate free radicals enabling its use in cancer treatment by Photodynamic Therapy (PDT). Unfortunately, up to know, the photo-excitation of ZnO-based materials’ requires excitation with ultraviolet light, which limits their biomedical applications. In this regard, this work investigates the effect of Ti species incorporation into the lattice of ZnO nanoparticles (NPs) with the aim of improving the corresponding optical properties and enabling the two-photoexcitation with 690nm-light (near infrared light). A modified polyol-based route was used to synthesize pure and Ti-doped (9% at.) ZnO NPs. X-ray diffraction confirmed the formation of ZnO-wurtzite whereas Scanning Electron Microscopy confirmed the formation of monodispersed 100-nm NPs. Raman Spectroscopy measurements evidenced the presence of zinc interstitials (Zni) and oxygen vacancies (VO) in the host oxide strcuture. Asynthesized NPs were excited using the technique of two-photon fluorescence microscopy (TPFM). The photoluminescence (PL) spectra generated from the analysis of TPFM images revealed a high emission peak presence in the green region (555 nm) that was assigned to VO. Also, a weak but noticeable band at 420 nm was detected, which is attributed to electron transition from the shallow donor level of Zni to the valence band. These PL transitions will favor triplet states formation necessary to yield cytotoxic reactive oxygen species. Furthermore, the presence of the PL peaks confirmed the Ti-ZnO NPs capacity to be excited by 690-nm light, thus, opening new possibilities for this NPs to be used in lightinduced bio-medical applications.

Confocal microscopy to guide laser ablation of basal cell carinoma: a preliminary feasibility study

Laser ablation may be a promising method for removal of skin lesions, with the potential for better cosmetic outcomes and reduced scarring and infection. An obstacle to implementing laser ablation is that the treatment leaves no tissue for histopathological analysis. Pre-operative and intra-operative mapping of BCCs using confocal microscopy may guide the ablation of the tumor until all tumor is removed. We demonstrate preliminary feasibility of confocal microscopy to guide laser ablation of BCCs in freshly excised tissue from Mohs surgery. A 2940 nm Er:YAG laser provides efficient ablation of tumor with reduced thermal damage to the surrounding tissue.

Fluorescein as a contrast agent for confocal intra-operative imaging of basal cell carcinomas: a preliminary ex vivo study

When used for intra-operative imaging of residual basal cell carcinomas (BCCs), reflectance confocal microscopy (RCM) is limited to detection of relatively large tumors. Small tumors remain hidden in the surrounding bright dermis. Fluorescence confocal microscopy (FCM) may improve the sensitivity for detecting small tumors. Fluorescein enhances cell cytoplasm contrast in fluorescence confocal images, but has had limited clinical impact on imaging BCCs in vivo because there is a lack of a well-defined protocol (concentration and application time) that can be effectively used for intraoperative imaging. We conducted an ex vivo study, using discarded tissue from Mohs surgery and a benchtop FCM with 488nm wavelength for excitation and 521nm detection for imaging Concentrations of 6, 0.6 and 0.6 mM with immersion times of 5, 15, 30, and 60 seconds were repeatedly tested (total of 76 specimens).. The 0.6 mM and immersion time of 60 seconds showed that cellular cytoplasm can be labeled with controlled saturation and without leaving the yellow color on the surface of the tissue. Initial results show that, fluorescein may enhance cellular structures contrast relative to other normal dermal structures, improving the detection of small BCCs. This study provide an optimized set of parameters for subsequently testing of topical application in vivo for intraopertive imaging of BCCs.

Latest advances in confocal microscopy of skin cancers toward guiding patient care: a Mohs surgeon's review and perspective (Conference Presentation)

Latest advances in confocal microscopy of skin cancers toward guiding patient care: a Mohs surgeon’s review and perspective About 350 publications worldwide have reported the ability of reflectance confocal microscopy (RCM) imaging to detect melanocytic skin lesions in vivo with specificity of 84-88% and sensitivity of 71-92%, and non-melanocytic skin lesions with specificity of 85-97% and sensitivity 100-92%. Lentigo maligna melanoma can be detected with sensitivity of 93% and specificity 82%. While the sensitivity is comparable to that of dermoscopy, the specificity is 2X superior, especially for lightly- and non-pigmented lesions. Dermoscopy combined with RCM imaging is proving to be both highly sensitive and highly specific. Recent studies have reported that the ratio of equivocal (i.e., would have been biopsied) lesions to detected melanomas dropped by ~2X when guided by dermoscopy and RCM imaging, compared to that with dermoscopy alone. Dermoscopy combined with RCM imaging is now being implemented to guide noninvasive diagnosis (to rule out malignancy and biopsy) and to also guide treatment, with promising initial impact: thus far, about 3,000 patients have been saved from biopsies of benign lesions. These are currently under follow-up monitoring. With fluorescence confocal microscopy (FCM) mosaicing, residual basal cell carcinomas can be detected in Mohs surgically excised fresh tissue ex vivo, with sensitivity of 94-97% and specificity 89-94%. FCM mosaicing is now being implemented for guiding Mohs surgery. To date, about 600 Mohs procedures have been performed, guided with mosaicing, and with pathology being performed in parallel to confirm the final outcome. These latest advances demonstrate the promising ability of RCM and FCM to guide patient care.

Laser ablation of basal cell carcinomas guided by confocal microscopy

Laser ablation offers precise and fast removal of superficial and early nodular types of basal cell carcinomas (BCCs). Nevertheless, the lack of histological confirmation has been a limitation. Reflectance confocal microscopy (RCM) imaging combined with a contrast agent can offer cellular-level histology-like feedback to detect the presence (or absence) of residual BCC directly on the patient. We conducted an ex vivo bench-top study to provide a set of effective ablation parameters (fluence, number of passes) to remove superficial BCCs while also controlling thermal coagulation post-ablation to allow uptake of contrast agent. The results for an Er:YAG laser (2.9 um and pulse duration 250us) show that with 6 passes of 25 J/cm2, thermal coagulation can be effectively controlled, to allow both the uptake of acetic acid (contrast agent) and detection of residual (or absence) BCCs. Confirmation was provided with histological examination. An initial in vivo study on 35 patients shows that the uptake of contrast agent aluminum chloride) and imaging quality is similar to that observed in the ex vivo study. The detection of the presence of residual tumor or complete clearance was confirmed in 10 wounds with (additional) histology and in 25 lesions with follow-up imaging. Our results indicate that resolution is sufficient but further development and use of appropriate contrast agent are necessary to improve sensitivity and specificity. Advances in RCM technology for imaging of lateral and deep margins directly on the patient may provide less invasive, faster and less expensive image-guided approaches for treatment of BCCs.