Real-time tissue elastography: a helpful tool in the diagnosis of cutaneous melanoma?

Diagnostic accuracy of high-frequency ultrasound for cutaneous neoplasms: a narrative review of the literature

High-frequency ultrasound has been used to visualize depth and vascularization of cutaneous neoplasms, but little has been synthesized as a review for a robust level of evidence about the diagnostic accuracy of high-frequency ultrasound in dermatology. A narrative review of the PubMed database was performed to establish the correlation between ultrasound findings and histopathologic/dermoscopic findings for cutaneous neoplasms. Articles were divided into the following four categories: melanocytic, keratinocytic/epidermal, appendageal, and soft tissue/neural neoplasms. Review of the literature revealed that ultrasound findings and histopathology findings were strongly correlated regarding the depth of a cutaneous neoplasm. Morphological characteristics were correlated primarily in soft tissue/neural neoplasms. Overall, there is a paucity of literature on the correlation between high-frequency ultrasound and histopathology of cutaneous neoplasms. Further studies are needed to investigate this correlation in various dermatologic conditions.

Interventional Ultrasound in Dermatology: A Pictorial Overview Focusing on Cutaneous Melanoma Patients

Cutaneous melanoma incidence is increasing worldwide, representing an aggressive tumor when evolving to the metastatic phase. High-resolution ultrasound (US) is playing a growing role in the assessment of newly diagnosed melanoma cases, in the locoregional staging prior to the sentinel lymph-node biopsy procedure, and in the melanoma patient follow-up. Additionally, US may guide a number of percutaneous procedures in the melanoma patients, encompassing diagnostic and therapeutic modalities. These include fine needle cytology, core biopsy, placement of presurgical guidewires, aspiration of lymphoceles and seromas, and electrochemotherapy.

High-resolution quantitative acoustic microscopy of cutaneous carcinoma and melanoma: Comparison with histology

BACKGROUND

The increased incidence rate of skin cancers during the last decades is alarming. One of the significant difficulties in the histopathology of skin cancers is appearance variability due to the heterogeneity of diseases or tissue preparation and staining process. This study aims to investigate whether the high-resolution acoustic microscopy has the potential for identifying and quantitatively classifying skin cancers.

MATERIAL/METHODS

Unstained standard formalin-fixed skin tissue samples were used for ultrasonic examination. The high-frequency acoustic microscope equipped with the 320 MHz transducer was utilized to visualize skin structure. Fourier transform was performed to calculate the sound speed and attenuation in the tissue.

RESULTS

The acoustic images demonstrate good concordance with the traditional histology images. All histological features in the tumour were easily identifiable on acoustic images. Each skin cancer type has its combination of ultrasonic properties significantly different from the healthy skin.

CONCLUSIONS

High-resolution acoustic imaging strengthened with quantitative analysis shows a potential to work as an auxiliary imaging modality assisting pathologists to lean to the particular decision in doubtful cases. The method can also assist surgeon to ensure the complete resection of a tumour.

Differentiating melanoma and healthy tissues based on elasticity-specific Brillouin microspectroscopy

The main objective of the present study is to evaluate the use of Brillouin microspectroscopy for differentiation of melanoma and normal tissues based on elasticity measurements. Previous studies of malignant melanoma show that the lesion is stiffer than the surrounding healthy tissue. We hypothesize that elasticity-specific Brillouin spectroscopy can be used to distinguish between healthy and cancerous regions of an excised melanoma from a Sinclair miniature swine. Brillouin measurements of non-regressing and regressing melanomas and the surrounding healthy tissues were performed. Based on the Brillouin measurements, the melanomas and healthy tissues can be successfully differentiated. The stiffness of both tumors is found to be significantly greater than the healthy tissues. Notably, we found that the elasticity of regressing melanoma is closer to that of the normal tissue. The results indicate that Brillouin spectroscopy can be utilized as a tool for elasticity-based differentiation between malignant melanoma and surrounding healthy tissue, with potential use for melanoma boundary identification, monitoring tumor progression, or response to treatment.

Ultrasonographic elastography in the evaluation of normal and pathological skin - a review

The aim of this review article is to discuss the role of ultrasonographic elastography, a technique used to quantify tissue stiffness, in the evaluation of normal and pathological skin. A growing body of evidence suggests that elastography may be used for the diagnosis and monitoring of skin pathologies, in particular tumors, and fibrotic and sclerotic processes. Our knowledge about the elastographic parameters of normal skin is sparse, which together with the lack of reference values for cutaneous stiffness constitutes a serious limitation to the use of elastography in some medical disciplines, including aesthetic medicine.

Ultrasound and Infrared-Based Imaging Modalities for Diagnosis and Management of Cutaneous Diseases

Non-invasive bedside imaging tools are becoming more prevalent for assessing cutaneous lesions. Ultrasound used at specific frequencies allows us to assess margins of lesions to minimize the extent of the biopsy that is performed and improve cosmetic outcomes. Vascularity, seen on Doppler ultrasound and contrast-enhanced ultrasound, and stiffness, assessed on tissue elastography, can help differentiate between benign and malignant lesions for clinicians to be more judicious in deciding whether to biopsy. Moreover, research has shown the efficacy in using ultrasound in monitoring flares of hidradenitis suppurativa, a disease affecting apocrine gland-rich areas of the body, for which the current gold standard involves examining and scoring inflammatory lesions with the naked eye. Infrared-based modalities have also been on the uptrend to aid in clinical decision-making regarding suspiciousness of lesions. Reflectance confocal microscopy has lateral resolution that is comparable to histopathology and it has been shown to be an appropriate adjunctive tool to dermoscopy, specifically when evaluating melanomas. Optical coherence tomography has utility in determining lesion thickness because of its depth penetration, and spectrophotometric intracutaneous analysis is becoming more popular as a tool that can be used by general practitioners to know when to refer to dermatology regarding worrisome pigmented lesions. Strides have been made to incorporate electrical impedance spectroscopy alongside dermoscopy in decision-making regarding excision, although the evidence for its use in the clincial setting remains inconclusive. This paper reviews the efficacy and drawbacks of these techniques in the field of dermatology and suggests future directions.

Assessment of Cutaneous Melanoma by Use of Very- High-Frequency Ultrasound and Real-Time Elastography

OBJECTIVE

The primary objective of this study was to evaluate the usefulness of very-high-frequency ultrasound as tool for assessment of skin melanoma by investigation of the correlation between the ultrasound measurement of the thickness of a melanoma and the histopathologically measured Breslow index. The secondary objective was to assess the potential role of real-time elastography in the preoperative evaluation of skin melanoma.

SUBJECTS AND METHODS

The study included 42 cutaneous melanoma lesions in 39 adult subjects examined in the division of ultrasound of a department of radiology between September 2011 and January 2015. Gray-scale sonographic features at 40 MHz (thickness, echogenicity, contour) and real-time strain elastographic (qualitative and semiquantitative, strain ratio) characteristics were evaluated and compared with the pathologic results.

RESULTS

The melanoma lesions had a homogeneous hypoechoic appearance with a regular contour and stiff or medium consistency. The mean difference between Breslow index and ultrasound thickness was -0.05 mm (95% CI, -0.24 to 0.13 mm), sustaining the absence of significant differences between these two measurements. A strong relation was identified between real-time elastographic appearance and strain ratio for the relations between lesion and hypodermis and between lesion and neighboring dermis (p < 0.002) or hypodermis.

CONCLUSION

Our study showed that very-high-frequency ultrasound and real-time elastography can be useful examinations for comprehensive preoperative evaluation of cutaneous melanoma.

Quantified ultrasound elastography in the assessment of cutaneous carcinoma

OBJECTIVE

To evaluate the feasibility of high-frequency ultrasound and ultrasound elastography (USE) in discriminating benign from malignant skin lesions in a prospective cohort study and to introduce the use of a "strain ratio" for evaluation of skin lesions.

METHODS

A commercial ultrasound system with a 14-MHz transducer was used to visualize skin lesions requiring biopsy on clinical evaluation. Anatomic ultrasound and USE imaging of the skin lesions was performed using 2- to 4-mm gel stand-off pads. A region of interest was manually selected over the area of each lesion with the lowest strain. The concept of a strain ratio of the compressibility of the normal skin at the corresponding layer to that of the least compressible region of a lesion in question was created and applied. This ratio was subsequently correlated with blind histopathological evaluation for malignancy.

RESULTS

55 patients were included in the study with a total of 67 lesions evaluated. 29 lesions were malignant and 38 benign. All malignant lesions had strain ratios ≥3.9. All benign lesions had strain ratios ≤3.0. A diagnostic value between 3.0 and 3.9 would result in 100% sensitivity and specificity in the characterization of these lesions as malignant.

CONCLUSION

This pilot study demonstrated that USE plus strain ratio appears to be a promising modality in providing diagnostic determination between cancerous and benign primary solitary skin lesions prior to biopsy.

ADVANCES IN KNOWLEDGE

This is the first reported study applying an original mathematical elastographic ratio, or strain ratio, to evaluate primary solitary skin lesions.

New diagnostic aids for melanoma

Detection of melanoma at an early stage is crucial to improving survival rates in melanoma. Accurate diagnosis by current techniques including dermatoscopy remains difficult, and new tools are needed to improve our diagnostic abilities. This article discusses recent advances in diagnostic techniques including confocal scanning laser microscopy, MelaFind, SIAscopy, and noninvasive genomic detection, as well as other future possibilities to aid in diagnosing melanoma. Advantages and barriers to implementation of the various technologies are also discussed.