Stephen Mizzi

Thermographic Patterns of the Upper and Lower Limbs: Baseline Data

Objectives. To collect normative baseline data and identify any significant differences between hand and foot thermographic distribution patterns in a healthy adult population. Design. A single-centre, randomized, prospective study. Methods. Thermographic data was acquired using a FLIR camera for the data acquisition of both plantar and dorsal aspects of the feet, volar aspects of the hands, and anterior aspects of the lower limbs under controlled climate conditions. Results. There is general symmetry in skin temperature between the same regions in contralateral limbs, in terms of both magnitude and pattern. There was also minimal intersubject temperature variation with a consistent temperature pattern in toes and fingers. The thumb is the warmest digit with the temperature falling gradually between the 2nd and the 5th fingers. The big toe and the 5th toe are the warmest digits with the 2nd to the 4th toes being cooler. Conclusion. Measurement of skin temperature of the limbs using a thermal camera is feasible and reproducible. Temperature patterns in fingers and toes are consistent with similar temperatures in contralateral limbs in healthy subjects. This study provides the basis for further research to assess the clinical usefulness of thermography in the diagnosis of vascular insufficiency.

Hidden dangers revealed by misdiagnosed peripheral arterial disease using ABPI measurement

AIM The aim of this study was to compare ankle brachial indices (APBI) with pedal waveforms utilizing the continuous wave Doppler in a population with diabetes mellitus. METHODS A prospective study design was employed to investigate the ABPI in a cohort of 49 people with type 2 diabetes mellitus. ABPI assessment was completed using a portable handheld Doppler and ankle pressures of <0.9 were taken as suggestive of peripheral arterial disease (PAD). Arterial spectral waveforms in each foot were also recorded and compared to the ABPI readings. RESULTS Inconsistencies were identified between ABPIs and waveform interpretations in the study population. Approximately 35% of subjects had inconsistencies between their ABPI result and waveform interpretation in their right or left foot. CONCLUSIONS Both ABPIs and Doppler waveforms should be used in the assessment of people with diabetes in order to screen for PAD. This would ensure an accurate assessment of PAD and would allow initiation of appropriate secondary risk factor control measures.

Establishing Differences in Thermographic Patterns between the Various Complications in Diabetic Foot Disease

Aim To evaluate the potential of thermography as an assessment tool for the detection of foot complications by understanding the variations in temperature that occur in type 2 diabetes mellitus (DM). Methods Participants were categorized according to a medical examination, ankle brachial index, doppler waveform analysis, and 10-gram monofilament testing into five groups: healthy adult, DM with no complications, DM with peripheral neuropathy, DM with neuroischaemia, and DM with peripheral arterial disease (PAD) groups. Thermographic imaging of the toes and forefeet was performed. Results 43 neuroischaemic feet, 41 neuropathic feet, 58 PAD feet, 21 DM feet without complications, and 126 healthy feet were analyzed. The temperatures of the feet and toes were significantly higher in the complications group when compared to the healthy adult and DM healthy groups. The higher the temperatures of the foot in DM, the higher the probability that it is affected by neuropathy, neuroischaemia, or PAD. Conclusions Significant differences in mean temperatures exist between participants who were healthy and those with DM with no known complications when compared to participants with neuroischaemia, neuropathy, or PAD. As foot temperature rises, so does the probability of the presence of complications of neuropathy, neuroischaemia, or peripheral arterial disease.

Automated Segmentation and Temperature Extraction from Thermal Images of Human Hands, Shins and Feet

The use of thermography has been considered for a wide range of medical applications, which often require the extraction of temperature values from specific points of interest on the human body. However, temperature extraction is typically carried out manually, rendering the process both lengthy as well as highly subjective. In this work we propose a number of methods to automatically segment and extract temperature readings from thermal images of human hands, shins and feet that can be employed in several clinical applications. Tests conducted using thermal images from the body regions of interest have shown that the implemented feature detection and region growing methods can provide accurate results with a correct detection rates of 100% in the case of the shin regions and detection rates above 90% for hand and foot regions.

The Application of Medical Thermography to Discriminate Neuroischemic Toe Ulceration in the Diabetic Foot

This study aimed to determine whether thermal imaging can detect temperature differences between healthy feet, nonulcerated neuroischemic feet, and neuroischemic feet with toe ulcers in patients with type 2 diabetes mellitus (T2DM). Participants were prospectively divided into 3 groups: T2DM without foot problems; a healthy, nonulcerated neuroischemic group, and an ulcerated neuroischemic group. Thermal images of the feet were obtained with automated segmentation of regions of interest. Thermographic images from 43 neuroischemic feet, 21 healthy feet, and 12 neuroischemic feet with active ulcer in one of the toes were analyzed. There was a significant difference in toe temperatures between the 3 groups (P = .001), that is, nonulcerated neuroischemic (n = 181; mean temperature = 27.7°C [±2.16 SD]) versus neuroischemic ulcerated (n = 12; mean temperature = 28.7°C [±3.23 SD]), and healthy T2DM group (n = 104; mean temperature = 24.9°C [±5.04 SD]). A post hoc analysis showed a significant difference in toe temperatures between neuroischemic nonulcerated and healthy T2DM groups (P = .001), neuroischemic ulcerated and healthy groups (P = .001). However, no significant differences in toe temperatures were identified between the ulcerated neuroischemic and nonulcerated neuroischemic groups (P = .626). There were no significant differences between the ulcerated toes (n = 12) and the nonulcerated toes (n = 57) of the same foot in the ulcerated neuroischemic group (P = .331). Toe temperatures were significantly higher in neuroischemic feet with or without ulceration compared with healthy feet in patients with T2DM. There were no significant differences in temperatures of ulcerated toes and the nonulcerated toes of the same foot, implying that all the toes of the same foot could potentially be at risk of developing complications, which can be potentially detected by infrared thermography.

The identification of higher forefoot temperatures associated with peripheral arterial disease in type 2 diabetes mellitus as detected by thermography

AIMS The purpose of this study was to investigate whether heat emitted from the feet of patients with type 2 diabetes (DM) and peripheral arterial disease (PAD) differed from those with type 2 diabetes without complications (DM). METHODS A non-experimental, comparative prospective study design was employed in a tertiary referral hospital. Out of 223 randomly selected participants (430 limbs) who were initially tested, 62 limbs were categorized as DM+PAD and 22 limbs as DM without PAD. Subjects with evidence of peripheral neuropathy were excluded. Participants underwent thermographic imaging. Automatic segmentation of regions of interest extracted the temperature data. RESULTS A significant difference in temperature in all the toes between the two groups was found (p=0.005, p=0.033, p=0.015, p=0.038 and p=0.02 for toes 1-5 respectively). The mean forefoot temperature in DM+PAD was significantly higher than that in DM (p=.019), with DM+PAD having a higher mean temperature (28.3°C) compared to DM (26.2°C). Similarly, the toes of subjects with DM+PAD were significantly warmer than those of subjects with DM only. CONCLUSIONS Contrary to expectations the mean toe and forefoot temperatures in DM patients with PAD is higher than in those with DM only. This unexpected result could be attributed to disruption of noradrenergic vasoconstrictor thermoregulatory mechanisms with resulting increased flow through cutaneous vessels and subsequent increased heat emissivity. These results demonstrate that thermography may have potential in detecting PAD and associated temperature differences.

Interrater Reliability of Spectral Doppler Waveform: Analysis Among Podiatric Clinicians

BACKGROUND Spectral Doppler ultrasound examination of pedal arteries is one of the most frequently used noninvasive assessment methods by health-care professionals for the diagnosis and ongoing monitoring of people at risk for or living with peripheral arterial disease. The aim of this study was to determine the interrater reliability of the interpretation of spectral Doppler waveform analysis. METHODS An interrater reliability study was conducted among five experienced podiatric physicians at the University of Malta Research Laboratory (Msida, Malta). A researcher who was not a rater in this study randomly selected 229 printed spectral Doppler waveforms from a database held at the University of Malta. Each rater independently rated the qualitative spectral waveforms. RESULTS Interrater reliability of the spectral Doppler waveform interpretation was excellent among the five experienced podiatric physicians (α = 0.98). The intraclass correlation coefficient showed a high degree of correlation in waveform interpretation across raters ( P < .001). CONCLUSIONS This study demonstrates high interrater reliability in visual spectral Doppler interpretation among experienced clinicians. The current foot screening guidelines do not refer to spectral Doppler waveform analysis in their recommendations, which has been shown in studies to be an important modality for the diagnosis of peripheral arterial disease when ankle-brachial pressure indexes are falsely elevated in calcified arteries. If interpreted correctly, the information obtained can provide an indication of the presence of peripheral arterial disease and facilitate early management of this condition.

Plantar Pressure Distribution in Patients with Diabetic Peripheral Neuropathy and a First-Ray Amputation

BACKGROUND Elevated dynamic plantar pressures are a consistent finding in diabetic patients with peripheral neuropathy, with implications for plantar foot ulceration. This study aimed to investigate whether a first-ray amputation affects plantar pressures and plantar pressure distribution patterns in individuals living with diabetes and peripheral neuropathy. METHODS A nonexperimental matched-subject design was conducted. Twenty patients living with diabetes and peripheral neuropathy were recruited. Group 1 (n = 10) had a first-ray amputation and group 2 (n = 10) had an intact foot with no history of ulceration. Plantar foot pressures and pressure-time integrals were measured under the second to fourth metatarsophalangeal joints, fifth metatarsophalangeal joint, and heel using a pressure platform. RESULTS Peak plantar pressures under the second to fourth metatarsophalangeal joints were significantly higher in participants with a first-ray amputation ( P = .008). However, differences under the fifth metatarsophalangeal joint ( P = .734) and heel ( P = .273) were nonsignificant. Pressure-time integrals were significantly higher under the second to fourth metatarsophalangeal joints in participants with a first-ray amputation ( P = .016) and in the heel in the control group ( P = .046). CONCLUSIONS Plantar pressures and pressure-time integrals seem to be significantly higher in patients with diabetic peripheral neuropathy and a first-ray amputation compared with those with diabetic neuropathy and an intact foot. Routine plantar pressure screening, orthotic prescription, and education should be recommended in patients with a first-ray amputation.

Peak pressure data and pressure-time integral in the contralateral limb in patients with diabetes and a trans-tibial prosthesis

BACKGROUND Clinicians currently rely on observational clinical data pertaining to the biomechanics of the diabetic foot. However, advances in technology can objectively describe this. A thorough understanding of the functional and mechanical consequences following trans-tibial amputations is lacking. RESEARCH QUESTION Does a trans-tibial prostheses significantly increase peak plantar pressures and pressure time integrals in the intact foot of patients with type-2 diabetes and neuropathy? METHODS A prospective quantitative matched-subject design was employed. Twenty participants living with diabetes and peripheral sensory neuropathy were recruited. Ten participants presented with a trans-tibial amputation and 10 had intact feet. Participants were matched for gender, age, foot type and BMI. Peak plantar pressure and pressure time integral data were recorded using the Tekscan HR™ pressure mat system, using the two-step gait protocol. The Shapiro-Wilk test was used to determine normality of data. The Independent Samples t-test and the Mann Whitney U test were carried out to reject the null hypothesis. RESULTS Although no significant differences (p < 0.05) in mean peak plantar pressures were observed in all the foot masks analysed between the amputee and the control group, a significant difference (p = 0.002) in mean pressure time integrals was recorded with highest pressure time integral (PTI) values under the 2nd-4th metatarsophalangeal joint (MTP joint) for the trans-tibial amputee group. SIGNIFICANCE Cumulative exposure of both pressure and time can lead to tissue damage. PTI could be considered as an important contributory factor in determining ulcer formation. Elevated PTI under the 2nd-4th MTP joints sustained in the intact contralateral limb in patients using below knee prosthesis could possibly be due to gait alterations in this population. The preservation of the contralateral limb is of great concern and importance as this might impact patients mobility and quality of life.

Automated segmentation of regions of interest from thermal images of hands

Thermal imaging can provide an image of the surface temperature of an object in a non-contact and noninvasive manner, making it particularly appealing for use in medical applications. In applications where it is desirable to extract temperature data from anatomical regions of interest (ROIs) in a standardised and consistent manner, the use of automated segmentation and analysis techniques can provide a faster, more reliable and more consistent approach than manual segmentation of these ROIs. In this paper we present an algorithm which automatically extracts temperature data from eight ROIs in thermal images of the volar aspect of human hands. The algorithm first identifies the hand from the background in the thermal image and then identifies pixels which make up the fingers and the palm. Finally, eight ROIs are extracted from the identified regions. The methods proposed in this work can also be extended for the processing of similar visual images.