Digital measurement and analysis of wounds based on colour segmentation

Extended Perfusion Parameter Estimation from Hyperspectral Imaging Data for Bedside Diagnostic in Medicine

Background: Hyperspectral Imaging (HSI) has a strong potential to be established as a new contact-free measuring method in medicine. Hyperspectral cameras and data processing have to fulfill requirements concerning practicability and validity to be integrated in clinical routine processes. Methods: Calculating physiological parameters which are of significant clinical value from recorded remission spectra is a complex challenge. We present a data processing method for HSI remission spectra based on a five-layer model of perfused tissue that generates perfusion parameters for every layer and presents them as depth profiles. The modeling of the radiation transport and the solution of the inverse problem are based on familiar approximations, but use partially heuristic methods for efficiency and to fulfill practical clinical requirements. Results: The parameter determination process is consistent, as the measured spectrum is practically completely reproducible by the modeling sequence; in other words, the whole spectral information is transformed into model parameters which are easily accessible for physiological interpretation. The method is flexible enough to be applicable on a wide spectrum of skin and wounds. Examples of advanced procedures utilizing extended perfusion representation in clinical application areas (flap control, burn diagnosis) are presented.

The characteristics of pressure injury photographs from the electronic health record in clinical settings

AIMS AND OBJECTIVES

To analyse and understand the characteristics of pressure injury images stored in the electronic health record.

BACKGROUND

To improve the quality of pressure injury documentation, photographing pressure injuries and storing the images in the electronic health record are standard practices in many hospitals. As new technologies develop, the utilisation of computer-assisted image processing makes automatic measurement of pressure injury size and tissue segmentation through pressure injury images possible. The translation of new technological developments to pressure injury photography conducted in clinical environments faces obstacles such as the complexity of conditions in which photographs are taken.

DESIGN

A cross-sectional descriptive study.

METHODS

A set of 360 pressure injury images were obtained from a hospital in western Pennsylvania. These images were taken in clinical settings during daily wound care service. The authors reviewed the pressure injury images to analyse the relative position of the pressure injury in the images, the shooting angle of the digital camera and the clinical objects in the background.

RESULTS

Only 5.9% of the pressure injury images were confined to only the wound region. In 80.1% of the images, the pressure injury is located in the central part of the image. In 54.0% of the images, the lens of the digital camera was not pointed perpendicularly to the plane of the pressure injury.

CONCLUSIONS

Bedside wound assessment of pressure injuries and assessment from photographs of pressure injuries display reasonable agreement with pressure injury staging. To extract wound information (e.g., size and tissue type) from pressure injury images through novel image processing technologies, the characteristics of pressure injury images in clinical settings should be better understood during the development of tools for pressure injury image processing.

RELEVANCE TO CLINICAL PRACTICE

Our results can help image processing experts understand wound photography characteristics to shorten the gap between laboratory and clinical environments when translating new image processing technologies.

Automated measurement of pressure injury through image processing

AIMS AND OBJECTIVES

To develop an image processing algorithm to automatically measure pressure injuries using electronic pressure injury images stored in nursing documentation.

BACKGROUND

Photographing pressure injuries and storing the images in the electronic health record is standard practice in many hospitals. However, the manual measurement of pressure injury is time-consuming, challenging and subject to intra/inter-reader variability with complexities of the pressure injury and the clinical environment.

DESIGN

A cross-sectional algorithm development study.

METHODS

A set of 32 pressure injury images were obtained from a western Pennsylvania hospital. First, we transformed the images from an RGB (i.e. red, green and blue) colour space to a YC_b C_r colour space to eliminate inferences from varying light conditions and skin colours. Second, a probability map, generated by a skin colour Gaussian model, guided the pressure injury segmentation process using the Support Vector Machine classifier. Third, after segmentation, the reference ruler - included in each of the images - enabled perspective transformation and determination of pressure injury size. Finally, two nurses independently measured those 32 pressure injury images, and intraclass correlation coefficient was calculated.

RESULTS

An image processing algorithm was developed to automatically measure the size of pressure injuries. Both inter- and intra-rater analysis achieved good level reliability.

CONCLUSIONS

Validation of the size measurement of the pressure injury (1) demonstrates that our image processing algorithm is a reliable approach to monitoring pressure injury progress through clinical pressure injury images and (2) offers new insight to pressure injury evaluation and documentation.

RELEVANCE TO CLINICAL PRACTICE

Once our algorithm is further developed, clinicians can be provided with an objective, reliable and efficient computational tool for segmentation and measurement of pressure injuries. With this, clinicians will be able to more effectively monitor the healing process of pressure injuries.

Nontraditional Methods to Evaluate Wound Healing

BACKGROUND

Traditional evaluation of wound healing is sometimes subjective. It is necessary to develop qualitative and quantitative methods to enable more efficient and accurate evaluation of wounds. Recently, new techniques have been introduced and the correspondence between these techniques and clinician judgment is critical.

OBJECTIVE

Some nontraditional techniques that analyze wound healing were reviewed, which include measurements of the wound area, tissue color, skin barrier function, skin humidity, and keratinocyte morphology.

METHODS

This review article is based on medical research that focuses on the evaluation of wound healing.

RESULTS

Software-based and advanced device-based techniques generally provide more accurate and precise results than traditional ones, such as the ruler-based technique. Measurement of tissue color can also help to identify the type of tissue. Evaluation of skin barrier function can assist clinicians to analyze functional restoration of skin, whereas skin humidity demonstrates the exudate production status of the wound. In addition, keratinocyte morphology in the wound bed indicates quality of wound healing and side effects of treatment.

CONCLUSION

There is no gold standard method for qualitative and quantitative evaluation of wound healing. It is important to understand the type of wound, sample size, results obtained, advantages, and limitations of each technique.

Quality of measurements of acute surgical and traumatic wounds using a digital wound-analysing tool

The aim of this study was to assess the reliability of measurements using a wound-analysing tool and their interpretability. Wound surface areas and tissue types, such as granulation, slough and necrosis, in twenty digital photographs were measured using a specific software program. The ratio of these tissue types in a wound was calculated using a wound profile. We calculated the intraclass coefficient or κ for reliability, standard error of measurement (SEM) and smallest detectable change (SDC). The inter-rater reliability intraclass correlation coefficient (ICC) was 0·99 for surface area, 0·76 for granulation, 0·67 for slough and 0·22 for necrosis. The profiles gave an overall κ of 0·16. For test-retest reliability, the ICC was 0·99 for surface area, 0·81 for granulation, 0·80 for slough and 0·97 for necrosis. The agreement of the applied profiles in the test-retest was 66% (40-100). SEM and SDC for surface area were 0·10/0·27; for granulation, 6·88/19·08; for slough, 7·17/19·87; and for necrosis, 0·35/0·98, respectively. Measuring wound surface area and tissue types by means of digital photo analysis is a reliable and applicable method for monitoring wound healing in acute wounds in daily practice as well as in research.

Protease-modulating polyacrylate-based hydrogel stimulates wound bed preparation in venous leg ulcers--a randomized controlled trial

Background

Stringent control of proteolytic activity represents a major therapeutic approach for wound-bed preparation.

Objectives

We tested whether a protease-modulating polyacrylate- (PA-) containing hydrogel resulted in a more efficient wound-bed preparation of venous leg ulcers when compared to an amorphous hydrogel without known protease-modulating properties.

Methods

Patients were randomized to the polyacrylate-based hydrogel (n = 34) or to an amorphous hydrogel (n = 41). Wound beds were evaluated by three blinded experts using photographs taken on days 0, 7 and 14.

Results

After 14 days of treatment there was an absolute decrease in fibrin and necrotic tissue of 37.6 ± 29.9 percentage points in the PA-based hydrogel group and by 16.8 ± 23.0 percentage points in the amorphous hydrogel group. The absolute increase in the proportion of ulcer area covered by granulation tissue was 36.0 ± 27.4 percentage points in the PA-based hydrogel group and 14.5 ± 22.0 percentage points in the control group. The differences between the groups were significant (decrease in fibrin and necrotic tissue P = 0.004 and increase in granulation tissue P = 0.0005, respectively).

Conclusion

In particular, long-standing wounds profited from the treatment with the PA-based hydrogel. These data suggest that PA-based hydrogel dressings can stimulate normalization of the wound environment, particularly in hard-to-heal ulcers.

[Using the braden scale and photographs to assess pressure ulcer risk]

The objective of this paper was to identify critically ill patients at risk for pressure ulcer (PU) using the Braden scale and digital photographs. A sample of 42 subjects was evaluated for 15 days, between March and June 2009, in Fortaleza, Brazil. A total of 47 lesions were identified, 23 (48.9%) as stage I and 24 (51.1%) as stage II. It is necessary for nurses to become familiar with and adopt the technologies used to assess and treat PU in order to lessen the negative effects of this public health problem.

Superabsorbent dressings for copiously exuding wounds

Exudate control is important in the management of both acute and chronic wounds. A new category of absorbent dressings that contain superabsorbent particles promises high absorbency. The aim of this multicentre, prospective, non-comparative observational study was to evaluate the clinical efficacy and absorbent capacity of a superabsorbent dressing. Fifteen inpatients and outpatients with highly exuding wounds were included. Most patients (n=8) (53%) had chronic wounds; 20% (n=3) had ulcerating tumours. The superabsorbent dressing was used as a primary or a secondary dressing. Assessment was on day 0 (start), day 3 and day 7 (end of study). The study looked at wound bed and periwound skin condition, exudate production, pain upon dressing removal, reason for dressing removal, and frequency of dressing changes. A clinical visual scoring tool was used, together with digital photographs, which were assessed by the same experienced clinician. All 15 patients completed the study, during which no adverse events were noted. At day 7, maceration had reduced from 46.7% (n=7) at day 0 to 6.7% (n=1). After only 3 days, dressing change frequency was reduced from once daily to twice weekly in 80% (n=12) of patients. The superabsorbent dressing seems to reduce complications associated with exudate production, stimulate wound healing and increase patient comfort; it may also save time and costs for caregivers.

Randomized controlled single center study comparing a polyhexanide containing bio-cellulose dressing with silver sulfadiazine cream in partial-thickness dermal burns

OBJECTIVE

A prospective, randomized, controlled single center study was designed to evaluate clinical efficacy of a polyhexanide containing bio-cellulose dressing (group B) compared to a silver-sulfadiazine cream (group A) in sixty partial-thickness burn patients.

PATIENTS AND METHODS

Local ethics committee approval was obtained and patients consented. Parameters were: pain reduction (VAS), healing time and wound bed condition, comparing day 0 (start) versus day 14 (end), as well as, ease of dressing use and treatment costs.

RESULTS

All completed the study (n=30/n=30) and were included in the ITT analysis, with a total of 72 burns (group A: n=38, group B: n=34). We noted no differences in healing time. Pain reduction was significantly faster and better in group B (p<0.01). There were fewer dressing changes in group B, compared to group A. Ease of use for the bio-cellulose dressing was rated better compared to group A. In group B, € 95.20 was saved for a 10 day treatment period, compared to group A.

CONCLUSION

Group B demonstrated a better and faster pain reduction in the treated partial-thickness burns, compared to group A. The results indicate the polyhexanide containing bio-cellulose dressing to be a safe and cost effective treatment for partial-thickness burns.