Quantitative discrimination of pigmented lesions using three-dimensional high-resolution ultrasound reflex transmission imaging

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.

Noninvasive imaging exploration of phacomatosis pigmentokeratotica using high-frequency ultrasound and optical coherence tomography: Can biopsy of PPK patients be avoided?

BACKGROUND

Phacomatosis pigmentokeratotica (PPK) is a distinct and rare type of epidermal nevus syndrome characterized by coexisting nonepidermolytic organoid sebaceous nevus (SN) with one or more speckled lentiginous nevi (SLN). Atypical nevi including compound Spitz and compound dysplastic may manifest within regions of SLN. Patients with PPK, or similar atypical nevus syndromes, may be subject to a significant lifetime number of biopsies, leading to pain, scarring, anxiety, financial burden, and decreased quality of life. The current literature includes case reports, genetics, and associated extracutaneous symptoms of PPK, but use of noninvasive imaging techniques have not been explored. We aim to investigate the value of high-frequency ultrasound (HFUS) and optical coherence tomography (OCT) in discriminating morphological features of pigmented lesions and nevus sebaceous within one patient with PPK.

MATERIALS AND METHODS

Two modalities, (1) HFUS imaging, based on acoustic properties and (2) OCT imaging, based on optical properties, were used to image a patient with PPK. Benign pigmented lesions, which may raise clinical suspicion for significant atypia, and nevus sebaceous, were selected on different areas of the body to be studied.

RESULTS

Five pigmented lesions and one area of nevus sebaceous were imaged and analyzed for noninvasive features. Distinct patterns of hypoechoic features were seen on HFUS and OCT.

CONCLUSION

HFUS provides a deep view of the tissue, with ability to differentiate gross structures beneath the skin. OCT provides a smaller penetration depth and a higher resolution. We have described noninvasive features of atypical nevi and nevus sebaceous on HFUS and OCT, which indicate benign etiology.

Automated Skin Lesion Classification on Ultrasound Images

The growing incidence of skin cancer makes computer-aided diagnosis tools for this group of diseases increasingly important. The use of ultrasound has the potential to complement information from optical dermoscopy. The current work presents a fully automatic classification framework utilizing fully-automated (FA) segmentation and compares it with classification using two semi-automated (SA) segmentation methods. Ultrasound recordings were taken from a total of 310 lesions (70 melanoma, 130 basal cell carcinoma and 110 benign nevi). A support vector machine (SVM) model was trained on 62 features, with ten-fold cross-validation. Six classification tasks were considered, namely all the possible permutations of one class versus one or two remaining classes. The receiver operating characteristic (ROC) area under the curve (AUC) as well as the accuracy (ACC) were measured. The best classification was obtained for the classification of nevi from cancerous lesions (melanoma, basal cell carcinoma), with AUCs of over 90% and ACCs of over 85% obtained with all segmentation methods. Previous works have either not implemented FA ultrasound-based skin cancer classification (making diagnosis more lengthy and operator-dependent), or are unclear in their classification results. Furthermore, the current work is the first to assess the effect of implementing FA instead of SA classification, with FA classification never degrading performance (in terms of AUC or ACC) by more than 5%.

Usefulness of High-Frequency Ultrasonography in the Diagnosis of Melanoma: Mini Review

High-frequency equipment is characterized by ultrasound probes with frequencies of over 10 MHz. At higher frequencies, the wavelength decreases, which determines a lower penetration of the ultrasound beam so as to offer a better evaluation of the surface structures. This explains the growing interest in ultrasound in dermatology. This review examines the state of the art of high-frequency ultrasound (HFUS) in the assessment of skin cancer to ensure the high clinical approach and provide the best standard of evidence on which to base clinical and policy decisions.

[Histological verification of autofluorescence borders of periorbital skin tumors]

Tumor borders are one of the most significant characteristics of any tumor, including that of the skin.

PURPOSE

To compare histological borders of periorbital skin tumors with their autofluorescence borders built from the analysis of non-induced protoporphyrin IX autofluorescence.

MATERIAL AND METHODS

The study group included 8 patients with skin tumors of the eyelids, periorbital region, eyebrow and zygomatic regions aged 54-88 years. The tumors varied in size from 2 to 8 mm and all displayed signs of basal cell carcinoma (BCC). At admission, all the patients underwent non-induced autofluorescence diagnosis. The images were processed with the «CancerPlot» program. During radio excision, the autofluorescent border of each neoplasm was marked with a surgical incision of about 5 mm long and 2 mm deep.

RESULTS

Upon pathomorphological examination, solid BCC was identified in 7 cases. The remaining case was senile keratosis. All reference incisions were located in healthy tissues not farther than 1 mm from the tumor (or keratosis locus, correspondingly).

CONCLUSION

By the example of facial BCC, an evident correlation was established between histological borders of the tumor and its native (non-induced) protoporphyrin IX autofluorescence.

A Preliminary Study for Quantitative Assessment with HFUS (High- Frequency Ultrasound) of Nodular Skin Melanoma Breslow Thickness in Adults Before Surgery: Interdisciplinary Team Experience

Background:

Cutaneous melanoma is one of the most severe skin diseases. Nodular melanoma is the second melanoma subtype in order of frequency. The prognosis of skin melanoma depends on the vertical growth of the tumor (Breslow index). For this measurement, excisional biopsy is strongly recommended. This is, however, an invasive procedure and may cause damage to the lymphatic drainage system. The HFUS system, , can be extremely useful for determining tumor thickness in the preoperative phase, given its high resolution capacity. The aim of this preliminary study is to define the role of HFUS for the nodular skin melanoma Breslow thickness in adults before surgery by making a comparison with histological features.

Methods:

In this study, 14 melanocytic lesions (8 male and 6 female) were evaluated with dermatoscopic clinical features strongly indicative of nodular melanoma. Out of these, excisional biopsy of 7 lesions was requested. The ultrasounds were performed preoperatively. The images were acquired through the first ultrasound scanner with ultra-high frequency probes (range from 50MHz to 70 MHz) available on the market under the EEC mark (Vevo "MD, FUJIFILM Visual Sonics, Amsterdam, the Netherlands) equipped with a linear probe of 50-70 MHz.

Results:

From the ultrasonographic analysis of 14 nodular melanoma thickness was determined for the presence of two hyperechogenic laminae, separated by a hypo / anechoic space. The twelve lesions were in situ while the other two lesions showed ultrasonography for example; the satellite lesions (less than two centimeters from the primary lesion) and in transit (localizable to more than two centimeters from the primary lesion). Four of these lesions were ulcerated. A comparsion was made the 7 lesions on between the thickness calculated with this method, and that obtained on the bioptic piece. The presence of a positive concordance has been evident in all of the cases.

Conclusions:

If further studies are needed to support its widespread clinical use, its is believed that, in expert hands and with an interdisciplinary team, HFUS is already capable to reliably calculate a Breslow index in a large majority of patients with cutaneous melanoma.

High-frequency ultrasound for diagnosing skin cancer in adults

BACKGROUND

Early, accurate detection of all skin cancer types is essential to guide appropriate management and to improve morbidity and survival. Melanoma and squamous cell carcinoma (SCC) are high-risk skin cancers with the potential to metastasise and ultimately lead to death, whereas basal cell carcinoma (BCC) is usually localised, with potential to infiltrate and damage surrounding tissue. Anxiety around missing early curable cases needs to be balanced against inappropriate referral and unnecessary excision of benign lesions. Ultrasound is a non-invasive imaging technique that relies on the measurement of sound wave reflections from the tissues of the body. At lower frequencies, the deeper structures of the body such as the internal organs can be visualised, while high-frequency ultrasound (HFUS) with transducer frequencies of 20 MHz or more has a much lower depth of tissue penetration but produces a higher resolution image of tissues and structures closer to the skin surface. Used in conjunction with clinical and/or dermoscopic examination of suspected skin cancer, HFUS may offer additional diagnostic information compared to other technologies.

OBJECTIVES

To assess the diagnostic accuracy of HFUS to assist in the diagnosis of a) cutaneous invasive melanoma and atypical intraepidermal melanocytic variants, b) cutaneous squamous cell carcinoma (cSCC), and c) basal cell carcinoma (BCC) in adults.

SEARCH METHODS

We undertook a comprehensive search of the following databases from inception up to August 2016: Cochrane Central Register of Controlled Trials; MEDLINE; Embase; CINAHL; CPCI; Zetoc; Science Citation Index; US National Institutes of Health Ongoing Trials Register; NIHR Clinical Research Network Portfolio Database; and the World Health Organization International Clinical Trials Registry Platform. We studied reference lists as well as published systematic review articles.

SELECTION CRITERIA

Studies evaluating HFUS (20 MHz or more) in adults with lesions suspicious for melanoma, cSCC or BCC versus a reference standard of histological confirmation or clinical follow-up.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted all data using a standardised data extraction and quality assessment form (based on QUADAS-2). Due to scarcity of data and the poor quality of studies, we did not undertake a meta-analysis for this review. For illustrative purposes, we plot estimates of sensitivity and specificity on coupled forest plots.

MAIN RESULTS

We included six studies, providing 29 datasets: 20 for diagnosis of melanoma (1125 lesions and 242 melanomas) and 9 for diagnosis of BCC (993 lesions and 119 BCCs). We did not identify any data relating to the diagnosis of cSCC.Studies were generally poorly reported, limiting judgements of methodological quality. Half the studies did not set out to establish test accuracy, and all should be considered preliminary evaluations of the potential usefulness of HFUS. There were particularly high concerns for applicability of findings due to selective study populations and data-driven thresholds for test positivity. Studies reporting qualitative assessments of HFUS images excluded up to 22% of lesions (including some melanomas) due to lack of visualisation in the test.Derived sensitivities for qualitative HFUS characteristics were at least 83% (95% CI 75% to 90%) for the detection of melanoma; the combination of three features (lesions appearing hypoechoic, homogenous and well defined) demonstrating 100% sensitivity in two studies (lower limits of the 95% CIs were 94% and 82%), with variable corresponding specificities of 33% (95% CI 20% to 48%) and 73% (95% CI 57% to 85%), respectively. Quantitative measurement of HFUS outputs in two studies enabled decision thresholds to be set to achieve 100% sensitivity; specificities were 93% (95% CI 77% to 99%) and 65% (95% CI 51% to 76%). It was not possible to make summary statements regarding HFUS accuracy for the diagnosis of BCC due to highly variable sensitivities and specificities.

AUTHORS' CONCLUSIONS

Insufficient data are available on the potential value of HFUS in the diagnosis of melanoma or BCC. Given the between-study heterogeneity, unclear to low methodological quality and limited volume of evidence, we cannot draw any implications for practice. The main value of the preliminary studies included may be in providing guidance on the possible components of new diagnostic rules for diagnosis of melanoma or BCC using HFUS that will require future evaluation. A prospective evaluation of HFUS added to visual inspection and dermoscopy alone in a standard healthcare setting, with a clearly defined and representative population of participants, would be required for a full and proper evaluation of accuracy.

Automatic Differential Diagnosis of Melanocytic Skin Tumors Using Ultrasound Data

We describe a novel automatic diagnostic system based on quantitative analysis of ultrasound data for differential diagnosis of melanocytic skin tumors. The proposed method has been tested on 160 ultrasound data sets (80 of malignant melanoma and 80 of benign melanocytic nevi). Acoustical, textural and shape features have been evaluated for each segmented lesion. Using parameters selected according to Mahalanobis distance and linear support vector machine classifier, we are able to differentiate malignant melanoma from benign melanocytic skin tumors with 82.4% accuracy (sensitivity = 85.8%, specificity = 79.6%). The results indicate that high-frequency ultrasound has the potential to be used for differential diagnosis of melanocytic skin tumors and to provide supplementary information on lesion penetration depth. The proposed system can be used as an additional tool for clinical decision support to improve the early-stage detection of malignant melanoma.

Methods of Melanoma Detection

Detection and removal of melanoma, before it has metastasized, dramatically improves prognosis and survival. The purpose of this chapter is to (1) summarize current methods of melanoma detection and (2) review state-of-the-art detection methods and technologies that have the potential to reduce melanoma mortality. Current strategies for the detection of melanoma range from population-based educational campaigns and screening to the use of algorithm-driven imaging technologies and performance of assays that identify markers of transformation. This chapter will begin by describing state-of-the-art methods for educating and increasing awareness of at-risk individuals and for performing comprehensive screening examinations. Standard and advanced photographic methods designed to improve reliability and reproducibility of the clinical examination will also be reviewed. Devices that magnify and/or enhance malignant features of individual melanocytic lesions (and algorithms that are available to interpret the results obtained from these devices) will be compared and contrasted. In vivo confocal microscopy and other cellular-level in vivo technologies will be compared to traditional tissue biopsy, and the role of a noninvasive "optical biopsy" in the clinical setting will be discussed. Finally, cellular and molecular methods that have been applied to the diagnosis of melanoma, such as comparative genomic hybridization (CGH), fluorescent in situ hybridization (FISH), and quantitative reverse transcriptase polymerase chain reaction (qRT-PCR), will be discussed.

High-resolution ultrasound imaging of cutaneous lesions

High-resolution variable frequency ultrasound imaging is increasingly being used in the noninvasive evaluation of various cutaneous diseases. It plays a complimentary role to physical examination in the assessment of cutaneous lesions. It is the only imaging modality useful in the evaluation of superficial cutaneous lesions that are too small to be evaluated on computed tomography (CT) or magnetic resonance imaging (MRI) and is helpful in reducing invasive procedures like biopsies and fine needle aspirations. In this article, we seek to describe the relevance and basic principles of cutaneous ultrasound, imaging findings of normal skin, current applications of high-resolution ultrasound in the diagnosis and management of various dermatological conditions, along with the features of some commonly encountered lesions.

New diagnostics for melanoma detection: from artificial intelligence to RNA microarrays

Early detection of melanoma remains crucial to ensuring a favorable prognosis. Dermoscopy and total body photography are well-established noninvasive aids that increase the diagnostic accuracy of dermatologists in their daily routine, beyond that of a naked-eye examination. New noninvasive diagnostic techniques, such as reflectance confocal microscopy, multispectral digital imaging and RNA microarrays, are currently being investigated to determine their utility for melanoma detection. This review presents emerging technologies for noninvasive melanoma diagnosis, and discusses their advantages and limitations.

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.

State of the art of diagnostic technology for early-stage melanoma

In the past few decades, rapid improvements in noninvasive optical technologies have revolutionized the diagnosis of early-stage melanoma. Current knowledge and limitations of these tools will be reviewed in this article. Dermoscopy has been recognized as the 'gold standard' in the screening phase. Digital dermoscopy monitoring and total-body photography are used to identify so-called 'featureless' melanoma only on the criteria of change over time. Automated instruments, as well as optical and nonmorphological methods, are still under development, and offer many opportunities to improve the speed and accuracy of the diagnosis of melanoma and/or to reduce the need for expertise. Despite a penetration depth limited to the upper dermis, the quasi-histological imaging achieved by in vivo reflectance confocal microscopy has been demonstrated to significantly aid diagnostic accuracy for selected melanocytic lesions. Future perspectives on diagnostic instrumentation will also be explored.

Advances and short comings in the early diagnosis of melanoma

Malignant melanoma kills more people each year than any other skin cancer, with approximately 8000 lives lost and a cost of over 3 billion dollars annually in the US alone. Tumor depth is the most important prognostic factor in melanoma. Thus, early detection has the potential to diagnose melanoma when lesions are thinner, and to improve survival in primary melanomas. In this review, we discuss the implications, barriers, and advantages of melanoma screening, and describe the currently employed methods of detection, newly available modalities, and current areas of research. We also discuss the efficacy, advantages and disadvantages, and clinical practicality of each, and suggest various means of combining different methodologies as well as tailoring various strategies to individual patient needs.

Imaging of melanoma: usefulness of ultrasonography before and after contrast injection for diagnosis and early evaluation of treatment

High-frequency ultrasound (8–14 MHz) is routinely used to display cutaneous melanomas. Maximum thickness measurement (Breslow index) has been shown to be well correlated to histologic findings for lesions of more than 0.75 mm. Some morphological criteria (strong delineation, hypoechoic texture, homogeneity) have been reported to help differentiate between malignant and benign pigmented blue lesions, but remain insufficient. Vascular ultrasound analysis using Doppler mode provides additional information and showed good specificity for malignancy (90%–100%), but variable sensitivity (34%–100%). Recent advances in ultrasound imaging allow functional evaluation. Likewise, dynamic contrast-enhanced ultrasound using contrast medium injection and specific perfusion and quantification software showed promising results in clinical and preclinical trials for early prediction of tumor response to target treatments.

High-resolution ultrasonography assists the differential diagnosis of blue naevi and cutaneous metastases of melanoma

BACKGROUND

Metastases of cutaneous melanoma may simulate benign blue naevi clinically.

OBJECTIVES

To investigate the value of ultrasonography in the differential diagnosis of lesions that look similar clinically, i.e. blue naevi and cutaneous metastases of melanoma.

METHODS

Participants were invited for inclusion in the study if they had a cutaneous blue lesion clinically suggestive of a blue naevus or cutaneous metastasis of melanoma. After obtaining signed consent, the lesion was photographed and studied using dermoscopy and high-resolution ultrasonography before being removed for histological examination. Clinical, dermoscopic and ultrasonographic images were reviewed anonymously by four dermatologists to assign the diagnosis of blue naevus or metastasis of melanoma. The diagnostic performance of clinical examination, dermoscopy and sonography was assessed for the ability of each to differentiate between metastases of melanoma and blue naevi with reference to the histological diagnosis. Moreover, experts undertook a semeiological description of each ultrasonographic image according to seven items: location of the lesion, echogenicity, homogeneity, shape of the lesion, definition of margins, posterior acoustic shadow and increased posterior echogenicity.

RESULTS

  Twenty-eight patients were included with a total of 39 blue skin lesions, and 17 of the 28 patients had a previous history of melanoma. Interobserver agreement in the semeiological description of the sonographic images was good (κ≥0·6) for five of seven items. Sonography was more specific (94%) than clinical examination (77%) and dermoscopy (74%). The sonographic features contributing to the differential diagnosis were: location of the lesion (P=0·027), shape of the lesion (P<0·001), homogeneity (P=0·001) and increased posterior echogenicity (P=0·007).

CONCLUSIONS

Ultrasonography is a reproducible and specific tool that can assist the differential diagnosis between blue naevi and metastases of melanoma. A blue naevus is a homogeneous, hypoechoic, 'dish-shaped' lesion, located in the superficial dermis, whereas metastases of melanoma are 'potato-shaped', hypoechoic, heterogeneous lesions, located in the hypodermis.

Comparing the effectiveness of Q-switched Ruby laser treatment with that of Q-switched Nd:YAG laser for oculodermal melanosis (Nevus of Ota)

BACKGROUND AND OBJECTIVE

The objective of this study was to compare the efficacy and safety of Q-switched Ruby laser versus Q-switched neodymium:yttrium-aluminium-garnet (Nd:YAG) laser for oculodermal melanosis (Nevus of Ota) birthmarks in a large group of patients.

STUDY DESIGN/MATERIALS AND METHODS

A retrospective review was conducted of 94 patients with Nevus of Ota treated with a Q-switched Ruby laser and a Q-switched Nd:YAG laser over a 3-year period. The subjects' ages ranged from 3 to 64 years; there were 70 females and 24 males, all of whom were of Asian descent. The number of treatments ranged from 1 to 8. Duration of treatment ranged from 6 months to 3 years and 10 months, with a mean of 14 months. Patients (n=47) received Q-switched Ruby laser treatment (694 nm) using light dosages of 7-10 J cm(-2). Subsequent patients (n=47) received Q-switched Nd:YAG laser treatment (1064 nm) using light dosages of 7-10 J cm(-2). The primary efficacy measurement was the quantitative assessment of clearing and fading response using the DermaSpectrometer for the Q-switched Ruby laser group versus the Q-switched Nd:YAG laser group.

RESULTS

Based on a paired t-test, clinical and statistically significant differences in clearing and fading response were observed amongst the Q-switched Ruby laser-treated subjects as preferred to the appearance of Q-switched Nd:YAG laser-treated group (P<0.05). In both groups, transient hyperpigmentation resolved in all subjects within 6 months. Permanent hyperpigmentation or scarring was not observed in either group.

CONCLUSION

Use of a Q-switched Ruby laser resulted in better clearing and fading as compared with Q-switched Nd:YAG laser.

Ultrasound phase contrast thermal imaging with reflex transmission imaging methods in tissue phantoms

Thermal imaging measurements using ultrasound phase contrast have been performed in tissue phantoms heated with a focused ultrasound source. Back projection and reflex transmission imaging principles were used to detect sound speed-induced changes in the phase caused by an increase in the temperature. The temperature was determined from an empirical relationship for the temperature dependence on sound speed. The phase contrast was determined from changes in the sound field measured with a hydrophone scan conducted before and during applied heating. The lengthy scanning routine used to mimic a large two-dimensional array required a steady-state temperature distribution within the phantom. The temperature distribution in the phantom was validated with magnetic resonance (MR) thermal imaging measurements. The peak temperature was found to agree within 1 degrees C with MR, and good agreement was found between the temperature profiles. The spatial resolution was 0.3x0.3x0.3mm, comparing favorably with the 0.625x0.625x1.5-mm MR spatial resolution.

Preoperative measurement of thickness of cutaneous melanoma using high-resolution 20 MHz ultrasound imaging: A monocenter prospective study and systematic review of the literature

Histologic measurement of the thickness of melanoma is a major prognostic factor and governs the size of the surgical excision (1cm for melanomas less than 1 mm thick, 2 cm for melanomas thicker than 2 mm and 3 cm beyond 4 mm). To determine whether high-resolution ultrasound can be used to predict surgical margins and, thus, to operate on patients in a single procedure avoiding further re-excision, we performed a systematic review of studies published from January 1987 to June 2007 and a prospective study. The systematic review selected 14 studies comparing histologic and ultrasound measurements and showing correlation coefficients generally greater than 0.9. Data available from 7 of the 14 studies (total 869 patients) showed predictive values of adequate margins in at least 72% of lesions using preoperative measurement of ultrasound thickness. The prospective study included 31 patients referred with a primary melanoma from March 2005 to March 2007. Ultrasound measurement of thickness was possible except for thin melanomas (<0.4 mm) in areas with marked photoaging, in the plantar zone, and in the case of very thick melanomas exceeding the explored depth (7.6 mm). The average thickness was 1.96 mm measured by ultrasound (SD: 2.15) and 1.95 mm by histology (SD: 2.62) and the Bland and Altman graph showed moderate agreement between ultrasound and histology. Limits of agreement were estimated at -1.4 and +1.8, corresponding to relative limits of agreement of -40 to +80%. Ultrasound predicted appropriate margins (1, 2 or 3 cm wide according to sonometric thickness) in 26 of the 31 subjects (84%, 95% CI 66-95). Preoperative high-resolution ultrasound is a noninvasive examination that can help in choosing appropriate surgical margins and should reduce the need of partial or excisional biopsy before surgery, and the need for further re-excision.

Strategies for early melanoma detection: Approaches to the patient with nevi

Given its propensity to metastasize and the lack of effective therapies for most patients with advanced disease, early detection of melanoma is a clinical imperative. Although there are no noninvasive techniques for the definitive diagnosis of melanoma, and the "gold standard" remains biopsy with histologic examination, a variety of modalities may facilitate early melanoma diagnosis and the detection of new and changing nevi. This article reviews the general clinical principles of early melanoma detection and various modalities that are currently available or on the horizon, providing the clinician with an up to date understanding of management strategies for their patients with numerous or atypical nevi.

LEARNING OBJECTIVE

After completing this learning activity, participants should understand the clinical importance of early melanoma detection, appreciate the challenges of early melanoma diagnosis and which patients are at highest risk, know the general principles of early melanoma detection, be familiar with current and emerging modalities that may facilitate early melanoma diagnosis and the detection of new and changing nevi, know the advantages and limitations of each modality, and be able to practice a combined approach to the patient with numerous or clinically atypical nevi.

Feasibility of ultrasound phase contrast for heating localization

Ultrasound-based methods for temperature monitoring could greatly assist focused ultrasound visualization and treatment planning based on sound speed-induced change in phase as a function of temperature. A method is presented that uses reflex transmission integration, planar projection, and tomographic reconstruction techniques to visualize phase contrast by measuring the sound field before and after heat deposition. Results from experiments and numerical simulations employing a through-transmission setup are presented to demonstrate feasibility of using phase contrast methods for identifying temperature change. A 1.088-MHz focused transducer was used to interrogate a medium with a phase contrast feature, following measurement of the baseline reference field with a hydrophone. A thermal plume in water and a tissue phantom with multiple water columns was used in separate experiments to produce a phase contrast. The reference and phase contrast field scans were numerically backprojected and the phase difference correctly identified the position and orientation of the features. The peak temperature reconstructed from the phase shift was within 0.2 degrees C of the measured temperature in the plume. Simulated results were in good agreement with experimental results. Finally, employment of reflex transmission imaging techniques for adopting a pulse-echo arrangement was simulated, and its future experimental application is discussed.