Concepts, Role, and Advances on Nail Imaging

Advances in image-based diagnosis of nail disorders

This paper provides a comprehensive overview of image-based techniques, particularly focusing on their applications and advancements in the context of nail disorders. Nowadays, high-resolution digital cameras and dermoscopes enable dermatologists to capture detailed images of nail abnormalities, facilitating early diagnosis and meticulous tracking of disease progression. Onychoscopy is now a routine technique with well-known criteria for the diagnosis, but recent developments allow us to visualize certain diseases better. Imaging modalities like high-frequency ultrasound, magnetic resonance imaging, optical coherence tomography and confocal microscopy are being increasingly adopted for their superior diagnostic capabilities. These techniques are described in their technology, scanning protocols, normal findings, advantages and limitations. Moreover, the integration of technology in patient education has fostered a more informed patient population, capable of actively participating in their disease monitoring and treatment regimens. Proper training, validation, regulation and ethical considerations are, however, essential when integrating technology into healthcare practices. Imaging technologies that present the potential to add critical anatomical information to clinical diagnoses within reasonable costs and are available worldwide are the ones that will probably be used the most.

Ultrasound of Nails: Why, How, When

Nail disorders are frequently a challenge to diagnose correctly only based on clinical findings. Moreover, biopsies may leave scars due to damage to the nail matrix. Currently, high-frequency ultrasound (HFUS) with probes >15 MHz is the first-choice imaging technique to study the nail. Compared with other imaging tests such as computed tomography and magnetic resonance imaging, HFUS has the advantage of high-resolution imaging of the nail apparatus without exposure to radiation, contrast media, and the risk of claustrophobia of these other expensive imaging methods. Notably, the axial spatial resolution of HFUS is higher than computed tomography and magnetic resonance imaging; therefore, it can better discriminate the anatomical alterations. Our objective is to review the main applications of HFUS of the nail through literature analysis and illustration of cases of the most frequent pathologies found in our experience, exemplifying why, how, and when HFUS could help diagnose nail diseases.

How to Start on Dermatologic Ultrasound: Basic Anatomical Concepts, Guidelines, Technical Considerations, and Best Tips

Dermatologic ultrasound has grown exponentially during the last decades and has passed from the experimental phase to the routine daily practice in multiple countries. The performance of this imaging technique requires color Doppler ultrasound devices working with high-frequency probes, a trained operator on imaging and dermatologic conditions, and the performance of standardized protocols for obtaining the anatomical data properly. In this review, we analyze the ultrasonographic anatomy of the skin, hair, and nails, the technical requirements and considerations, the guidelines, and the recommended protocols, and provide the best tips for practicing this type of examination confidently.

Ultrasound Features of Nail Lichen Planus

OBJECTIVES

To describe the ultrasonographic features of nail lichen planus (NLP), which, so far, have not been reported in the literature.

METHODS

A retrospective single-center study of NLP patients' color Doppler ultrasound examinations was performed between March 2014 and January 2023. Inclusion criteria were patients ≥15 years with a confirmed clinical diagnosis of NLP in sequential order. Exclusion criteria included concomitant systemic or local cutaneous or nail diseases and systemic or local nail treatments before the ultrasound examination. The ultrasound protocol included the examination of all fingernails or toenails following the reported protocol for dermatologic ultrasound examinations at high and ultra-high frequencies. Patient demographics and ultrasound features of the nail bed, periungual region, nail plate, and regional vascularity were registered and analyzed statistically.

RESULTS

A total of 36 patients met the criteria. All cases presented thickened and decreased echogenicity of the nail bed. A hypoechoic halo surrounding the origin of the nail plate was present in 78% of cases. Exactly 58% of patients presented decreased echogenicity of the proximal periungual dermis, and 86% showed thickening of the periungual dermis. Hypervascularity of the nail bed was seen in 94% of cases. The mean maximum thickness of vessels, the peak systolic velocity of the arterial vessels, and other blood flow findings are provided.

CONCLUSION

Ultrasonography can support the diagnosis of NLP, which benefits the non-invasive discrimination of nail conditions and can avoid the potential permanent scars derived from nail biopsies. Furthermore, ultrasound may be a powerful tool to monitor this disease's treatment.

Ultrasound clinical references of the healthy toenail unit

The toenail unit, commonly called the nail, is one of the most frequently examined and treated structures in clinical podiatry. Ultrasound is a standard clinical technique because it is a noninvasive, painless, and rapid diagnostic tool. The main objective of this study was to obtain morphometric data of the healthy toenail unit by ultrasound for clinical application. The nails of 76 participants (152 hallux nails; 38 men, 38 women, average age 26.83 ± 12.20) were examined using a VINNO E35 ultrasound system and an X6-16L linear probe with a frequency of 18 MHz. Five ultrasound measures of the healthy toenail unit were obtained, of which only the distance from the center of the distal phalange to the nail plate varied with age, sex, weight, and foot (p-values ≤ 0.050). The other four parameters were less influenced by the variables analyzed, except sex, which influenced nearly all (p-values ≤ 0.050). In one of these variables, indications of significance were observed (p-values = 0.060), with greater distances in the men than in the women, except for nail plate curvature, which showed a higher value. The other variables studied did not influence the parameters analyzed. High-frequency ultrasound can be used to examine the healthy toenail unit and define anthropometric reference measurements that can be used for more accurate and comparative diagnosis.

Ultrasound imaging of onychopapilloma: Evaluation of 43 cases

INTRODUCTION

Onychopapilloma is a benign tumor presenting as an isolated benign warty distal matrix and bed lesion in association with longitudinal erythronychia for which no underlying cause can be identified. Diagnosis might be challenging due to other, more severe, causes of erythronychia.

OBJECTIVES

This study aimed to investigate the clinical and sonographic features of onychopapilloma using high-frequency ultrasound.

METHODS

Between February 2022 and May 2023, a cross-sectional study was conducted, involving 39 patients displaying clinical features suggestive of onychopapilloma. These patients were selected at random and underwent examination using high-frequency ultrasound. High-frequency ultrasound assessments of the nail unit were carried out using 33 MHz and 24 MHz high-frequency linear transducers. An experienced radiologist performed the ultrasound scans while participants assumed an orthostatic seated position. Subsequently, the collected ultrasound images were independently evaluated by two radiologists specializing in nail injuries, ensuring a blinded assessment. This evaluation aimed to provide comprehensive insights into the imaging characteristics of onychopapilloma.

RESULTS

High-frequency ultrasound revealed oval or linear hyperechoic masses located in the middle of the nail plate, without vascularity or posterior acoustic shadowing. Nail plate irregularity, thickening, and nail bed indentation were observed in some cases. These findings demonstrate that high-frequency ultrasound can aid in the diagnosis and surgical planning of onychopapilloma, providing detailed visualization of the lesion and surrounding structures.

CONCLUSIONS

This imaging method could represent a potential tool to differentiate onychopapilloma from other nail conditions, especially malignant neoplasms. However, further research is needed to validate these findings and assess long-term outcomes.

Ultrasound Features of Onychopapilloma at High-Frequency and Ultra-High Frequency

OBJECTIVE

This study aimed to identify the sonographic features of pathologically confirmed onychopapilloma cases.

METHODS

High-frequency up to 24 MHz and ultra-high frequency-ultrasound up to 71 MHz examinations were performed and correlated with their clinical and pathologic presentations.

RESULTS

Twenty-two cases met the criteria. Clinical presentations revealed longitudinal erythronychia in 63.3% of cases. The ultrasound examinations identified a hypoechoic band in the nail bed (86.3%), nail plate abnormalities including upward displacement (68.2%) and thickening (68.1%), focal hyperechoic focal spots on the nail plate (50%) and irregularities of the ventral plate (33.3%). Color Doppler imaging showed no hypervascularity of the nail bed in all studies. These findings correlate with histological characteristics of onychopapilloma, including nail bed acanthosis, papillomatosis, and layered hyperkeratosis. Recurrence occurred in two cases after surgery, with tumors showing proximal extension in the matrix region on ultrasound not evident during clinical examination.

CONCLUSION

High-frequency and ultra-high-frequency can provide anatomical information in onychopapilloma that could enhance understanding and management.

Key Points to Select a Device for Dermatologic Ultrasound

What points to consider when selecting a device for practicing dermatologic ultrasound is an excellent question. After we met the requisites published in the guidelines for practicing dermatologic ultrasound, it is necessary to consider the main objective of the use because it is not the same to be focused mostly on the avoidance of the puncture of important facial vessels such as the case of injectors of cosmetic fillers in comparison to the use of operators that need to deal with the diagnosis and monitoring of a wide range of dermatologic pathologies. Currently, a broad variety of ultrasound devices meets the minimum requirements for practicing these examinations in the market. Thus, small, portable, and high-end devices may present advantages and limitations that must be balanced according to the primary purposes and the budget. Moreover, the shape and footprint of the probes can make difficult or facilitate a dermatologic procedure. Other points to consider are the type of storage and the need for technical service. In summary, there are key points that we need to consider when we select a dermatologic ultrasound device in dermatology or aesthetics.

Systematic study on nail plate assessment: differences in nail plate shape, thickness, power Doppler signal and scanning approach

Ultrasonography (US) of the nail is raising interest in the last years and its feasibility, quickness and amount of descriptive data may provide valuable information. Different authors presented several scanning approaches to nail complex in different pathological conditions, such as psoriasis, but no scanning protocol was ever proposed using healthy subjects as population of reference. The aim of the study was to establish a protocol for the US of nail plate and to assess whether the measurement of the nail plate is influenced by longitudinal vs transverse scan, sex, digit and hand dominance. Using high frequency probe and a Canon Aplio i800 machine, ultrasonographers took scans of nail plates of the hands from healthy subjects. Nail plate shape, thickness and power Doppler signal (PDUS) were evaluated and scans were taken both on longitudinal and transverse axis, at distal, middle and proximal portion of the nail plate or at a fixed angles of - 45°, 0° or + 45°. All the images were then revised and scored using a DICOM software, in order to allow good standards of accuracy and reproducibility. A total of 27 subjects (14 females and 13 males) were assessed. The measures did not result to differ in different portions or angles. Furthermore, no difference appears in sex or dominant vs not dominant hand. A decreasing and significant trend for nail plate thickness was found from the first to the fifth finger. Doppler signal was found in all but one subjects, with a range from almost absent to very evident. No difference was found between groups regarding PDUS. The data provided suggest that a proper scan protocol should include all the nails and evaluation should be done both on longitudinal and transverse axis. Since Doppler signal is highly variable in healthy subjects, its presence should be carefully considered as pathological finding. Observations provided by this study clarify important points of the scanning technique and solve doubts related to which nails should be scanned and where to evaluate quantitative parameters.

Sonographic Features of Onychopapilloma: A Single Center Retrospective Observational Study

(1) Background: Onychopapilloma is a benign tumor of the nail bed and distal matrix. which usually manifests as monodactylous longitudinal eryhtronychia associated with subungual hyperkeratosis. The impossibility to rule out a malignant neoplasm is an indication for surgical excision and histological examination. Our aim is to report and describe the ultrasonographic features of onychopapilloma. (2) Methods: we conducted a retrospective analysis of patients with a histological diagnosis of onychopapilloma who underwent ultrasonographic examination in our Dermatology Unit from January 2019 to December 2021. (3) Results: Six patients were enrolled. Erythronychia, melanonychia, and splinter hemorrhages were the main dermoscopical findings. Ultrasonography detected nail bed dishomogeneity in three patients (50%) and a distal hyperechoic mass (5 patients, 83.3%). Color Doppler imaging did not show vascular flow in any of the cases. (4) Conclusions: the detection of a subungual distal non-vascularized hyperechoic mass by US, together with classical onychopapilloma clinical features, supports the diagnosis, especially in those patients who were unable to perform excisional biopsy.

Skin sonography in children: a review

Skin lesions are not uncommon in children, and most of them are benign. However, they can be a matter of concern. Although in most cases the diagnosis can be suspected based on clinical history and physical examination, in some cases clinical findings are nonspecific. High-frequency color Doppler US is a noninvasive technique that can play a relevant role in these cases and give important anatomical information for final clinical management. US can be helpful to avoid unnecessary surgery, plan a surgical excision and avoid advanced imaging studies such as MRI and CT, which have a lower resolution for the skin. Different lesions can look similar on US, and clinical correlation is always important. The purpose of this article is to show a variety of skin lesions that occur in children, emphasizing clinical-sonographic correlation, and to familiarize pediatric radiologists with the US technique and sonographic appearance of common skin lesions in children.