Facilitating clinically relevant skin tumor diagnostics with spectroscopy-driven machine learning.

In the dawning era of artificial intelligence (AI), health care stands to undergo a significant transformation with the increasing digitalization of patient data. Digital imaging, in particular, will serve as an important platform for AI to aid decision making and diagnostics. A growing number of studies demonstrate the potential of automatic pre-surgical skin tumor delineation, which could have tremendous impact on clinical practice.

Photoacoustic imaging of periorbital skin cancer : unique spectral signatures of malignant melanoma, basal, and squamous cell carcinoma.

Radical excision of periorbital skin tumors is difficult without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imagi--ng modality that has potential for intraoperative micrographic control of surgical margins. This is the first study to assess the feasibility of PA imaging for the detection of periocular skin cancer.

Laser Speckle Contrast Imaging of the Blood Perfusion in Glabellar Flaps Used to Repair Medial Canthal Defects.

Background: The glabellar flap is a common technique for surgical repair after tumor excision in the medial canthal area. However, the outcome may be affected by partial flap necrosis. Little is known about the impact of surgery on blood perfusion and the postoperative course of reperfusion due to the absence of reliable and noninvasive perfusion monitoring techniques.

Comparison of photoacoustic imaging and histopathological examination in determining the dimensions of 52 human melanomas and nevi .

Surgical excision followed by histopathological examination is the gold standard for the diagnosis and staging of melanoma. Reoperations and unnecessary removal of healthy tissue could be reduced if non-invasive imaging techniques were available for presurgical tumor delineation. However, no technique has gained widespread clinical use to date due to shallow imaging depth or the absence of functional imaging capability.

Automatic threshold selection algorithm to distinguish a tissue chromophore from the background in photoacoustic imaging.

The adaptive matched filter (AMF) is a method widely used in spectral unmixing to classify different tissue chromophores in photoacoustic images. However, a threshold needs to be applied to the AMF detection image to distinguish the desired tissue chromophores from the background. In this study, we propose an automatic threshold selection (ATS) algorithm capable of differentiating a target from the background, based on the features of the AMF detection image.

Blood Perfusion of Human Upper Eyelid Skin Flaps Is Better in Myocutaneous than in Cutaneous Flaps.

Background: The aim of this study was to monitor blood perfusion in human upper eyelid skin flaps and examine how the perfusion is affected by the thickness of the flap.

Methods: Twenty upper eyelids were dissected as part of a blepharoplasty procedure in patients. The medial end of the blepharoplasty flap remained attached to mimic a flap design often used in reconstruction in the periocular area, a myocutaneous flap in which the blood supply follows the fibers of the orbicularis muscle and is thus parallel to the long axis of the flap.

Laser Speckle Contrast Imaging of a Rotational Full-Thickness Lower Eyelid Flap Shows Satisfactory Blood Perfusion.

Full-thickness eyelid flaps from the lower eyelid are frequently used to repair larger upper eyelid defects. Perfusion monitoring has recently been implemented in several reconstructive surgical procedures, however, perfusion monitoring of a rotational eyelid flap has not yet been described. The authors' employed laser speckle contrast imaging to monitor blood perfusion in a rotational flap from the lower eyelid, used to cover a large tumor defect in the upper eyelid.

Erratum to "Blood perfusion in Hewes tarsoconjunctival flaps in pigs measured by laser speckle contrast imaging". JPRAS open, volume 18, December 2018, pages 98-103.

[This corrects the article DOI: 10.1016/j.jpra.

Novel Evidence Concerning Lacrimal Sac Movement Using Ultra-High-Frequency Ultrasound Examinations of Lacrimal Drainage Systems.

Purpose: Current hypothesis regarding the mechanism of active tear drainage is based on studies performed ex vivo or under nonphysiological conditions. Novel ultra-high-frequency ultrasound has the advantage of generating images with superior resolution, enabling measurements of low flow in small vessels, and the tracking of tissue motion in real time. The purpose of this study was to investigate the lacrimal drainage system and active drainage using this modality.

Perfusion in Upper Eyelid Flaps: Effects of Rotation and Stretching Measured With Laser Speckle Contrast Imaging in Patients.

Purpose: The aim of this study was to investigate how the blood perfusion in human upper eyelid skin flaps is affected by the length of the flap and the degree of stretching and rotation of the flap.

Methods: Twenty-nine upper eyelids were dissected as part of a blepharoplastic procedure in patients. The 1-cm wide proximal end of the flap remains attached, to mimic a random pattern skin flap (hereafter called a "skin flap").

Unique spectral signature of human cutaneous squamous cell carcinoma by photoacoustic imaging.

Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer with metastatic potential. To reduce reoperations due to nonradical excision, there is a need to develop a technique for identification of tumor margins preoperatively. Photoacoustic (PA) imaging is a novel imaging technology that combines the strengths of laser optics and ultrasound.

Blood Perfusion in Rotational Full-Thickness Lower Eyelid Flaps Measured by Laser Speckle Contrast Imaging.

Purpose: Large upper eyelid defects can be repaired by rotational full-thickness lower eyelid flaps. The aim was to measure the blood perfusion in such flaps, and how it is affected by the length of the flaps, and the degree of rotation and stretching.

Methods: Nine patients underwent the Quickert procedure for entropion repair in which a full-thickness eyelid flap of approximate width 0.

The Effect of Canthotomy on Blood Perfusion During the Repair of Lower Eyelid Defects.

Purpose: Canthotomy is frequently used to mobilize extra tissue when repairing larger lower eyelid defects. The aim of this study was to explore the effect of canthotomy on blood perfusion and oxygen tension.

Methods: Eight pigs underwent a wedge resection of the lower eyelid and canthotomy (with cantholysis involving the lateral palpebral artery).

Erratum to: Successful repair of a full upper eyelid defect following traumatic amputation by simply suturing it back in place, JPRAS Open volume 19, March 2019, pages 73-76.

[This corrects the article DOI: 10.1016/j.jpra.

Spectral Signatures in the Different Layers of the Human Eyelid by Photoacoustic Imaging.

Background And Objectives: The eyelids are susceptible to a number of skin cancers, which are challenging to excise radically without sacrificing excessive healthy tissue. Photoacoustic (PA) imaging is an emerging non-invasive biomedical imaging modality that could potentially be used for intraoperative micrographic control of the surgical margins of eyelid tumors. In this study, non-cancerous human eyelid tissue was characterized using PA as a first step in the development of this technique.

Revascularization of Free Skin Grafts Overlying Modified Hughes Tarsoconjunctival Flaps Monitored Using Laser-Based Techniques.

Purpose: It has recently been shown that the flap pedicle does not supply blood to a tarsoconjunctival graft in the modified Hughes procedure in patients. This raises questions concerning the rate of revascularization of the free skin graft commonly used to reconstruct the anterior lamella. The aim of this study was, thus, to monitor the course of revascularization in free skin grafts overlying modified Hughes tarsoconjunctival flaps, using laser-based techniques.

Maximal haemostatic effect is attained in porcine skin within 7 min of the administration of a local anaesthetic together with epinephrine, refuting the need for a 30 min waiting time.

Objective: Based on clinical experience gained over many years, the maximal haemostatic effect following administration of local anaesthetics containing epinephrine is generally believed to occur within 10 min. Surprisingly, it was found in a recent study, in which bleeding was quantified intraoperatively, that maximal haemostasis did not occur until 30 min. If this is indeed the case, then it would be necessary to extend the preoperative waiting time to minimize perioperative bleeding.

Successful repair of a full upper eyelid defect following traumatic amputation by simply suturing it back in place.

There is a general belief that a full-thickness eyelid defect is best repaired using a vascularized flap in combination with a free graft, and that a free full-thickness eyelid graft would not survive due to poor blood perfusion. However, we describe a case in which an upper eyelid was traumatically amputated. The eyelid was sutured in place and healed well .

Perfusion Monitoring Shows Minimal Blood Flow From the Flap Pedicle to the Tarsoconjunctival Flap.

Background: A previous study in pigs has shown that the pedicle of the tarsoconjunctival flap does not appear to have adequate blood perfusion. The aim of this study was to monitor perfusion in tarsoconjunctival flaps in patients with large lower eyelid defects resulting from tumor surgery.

Methods: The modified Hughes procedure was performed in 13 patients.

Hypoperfusion following the injection of epinephrine in human forearm skin can be measured by RGB analysis but not with laser speckle contrast imaging.

Background: The time taken for epinephrine to achieve its optimal effect during local anesthesia has recently become the subject of debate. The time from injection to commencement of surgery is traditionally quoted to be 7 to 10 min, while recent reports claim that it may take 30 min to achieve maximum hypoperfusion, which would prolong the time required for surgical procedures. The discrepancy may be related to difficulties associated with the techniques used to measure blood perfusion.

Blood perfusion in Hewes tarsoconjunctival flaps in pigs measured by laser speckle contrast imaging.

Background: Hewes flap is a tarsoconjunctival eyelid flap, based at the lateral canthal tendon, and rotated and stretched to repair lateral defects in the lower eyelid commonly following tumor surgery. The aim of the present study was to monitor perfusion in a Hewes flap during reconstruction, which to the best of our knowledge, has not previously been done.

Methods: A Hewes tarsoconjunctival eyelid flap was raised and the effects on blood perfusion of rotating the flaps by 90° and 180°, stretching the flaps with a force of 5 or 10 N, and repeated diathermic coagulation was monitored with laser speckle contrast imaging.

A waiting time of 7 min is sufficient to reduce bleeding in oculoplastic surgery following the administration of epinephrine together with local anaesthesia.

Objective: The time taken to reach maximal haemostatic effect following local anaesthesia with epinephrine is generally believed to be <10 min. This is based on clinical experience and indirect measurements of perfusion using methods such as laser Doppler flowmetry and oxygen spectroscopy. However, the only study in which bleeding has been measured quantitatively in an intra-operative setting in humans showed that the full haemostatic effect was not achieved until 30 min after anaesthesia.

Blood Perfusion in Human Eyelid Skin Flaps Examined by Laser Speckle Contrast Imaging-Importance of Flap Length and the Use of Diathermy.

Purpose: It is well known that blood perfusion is important for the survival of skin flaps. As no study has been conducted to investigate how the blood perfusion in human eyelid skin flaps is affected by the flap length and diathermy, the present study was carried out to investigate these in patients.

Methods: Fifteen upper eyelids were dissected as part of a blepharoplastic procedure, releasing a 30-mm long piece of skin, while allowing the 5 mm wide distal part of the skin to remain attached, to mimic a skin flap (hereafter called a "skin flap").