Inter-Device Concordance in the Measurement of Plantar Thermal Asymmetry: Comparative Evaluation of a Low-Cost Thermographic Camera (HIKMICRO Mini2 V2) Versus a High-Resolution Camera (HIKMICRO M60) in Patients With Diabetes Mellitus
试验速览
- 阶段
- 不适用
- 状态
- 尚未招募
- 发起方
- 入组人数
- 130
- 试验地点
- 1
- 主要终点
- Intraclass correlation coefficient for absolute agreement, ICC(A,1), between the two cameras for contralateral thermal asymmetry (Delta T) in each of six pre-specified plantar regions of interest
研究概览
简要总结
This cross-sectional observational study measures the inter-device concordance between two infrared thermographic cameras, a low-cost model (HIKMICRO Mini2 V2) and a high-resolution model (HIKMICRO M60), when measuring plantar skin temperature in adults with diabetes mellitus. Each participant undergoes two consecutive thermographic acquisitions, always less than 10 seconds apart, from a fixed tripod at 75 cm, under standardized environmental conditions. The order of the two cameras is randomized 1:1 at participant level (sequence A: M60 then Mini2 V2; sequence B: Mini2 V2 then M60). The primary endpoint is the agreement between the two devices for contralateral thermal asymmetry (Delta T) in each of six pre-specified plantar regions of interest (ROIs), quantified by the intraclass correlation coefficient (ICC) for absolute agreement, with the consistency ICC for mean plantar temperature (Tmean) as an exploratory endpoint.
The study is strictly metrological. Neither camera is a medical device under Regulation (EU) 2017/745, no clinical decision is derived from the measurements, and the study does not evaluate the detection, diagnosis, screening or prevention of any disease. Neither device is designated as a diagnostic reference standard. Participants with diabetes mellitus are included solely because plantar thermal variability is greater in this population, which makes the inter-device comparison metrologically demanding.
详细描述
Each participant is assessed in a single session in a thermally stable room at 20 to 25 degrees Celsius, with relative humidity recorded as a covariate. After 15 minutes of acclimatization in a semi-Fowler position with the backrest at 30 to 45 degrees, both cameras acquire plantar thermograms from a static tripod at a fixed distance of 75 cm, with the tripod head at 90 degrees to the plantar plane and an emissivity setting of 0.98. The two radiometric acquisitions are consecutive and always less than 10 seconds apart. The order of the cameras is randomized 1:1 at participant level (sequence A: M60 then Mini2 V2; sequence B: Mini2 V2 then M60), from a list generated in advance by a team member not involved in image acquisition and kept in a password-protected file until recruitment is complete. No specific background is used.
Thermograms are exported to HIKMICRO Analyzer version 2.0.1. Six anatomical regions of interest, defined a priori and identical for both cameras, are delimited on each foot: hallux, first, third and fifth metatarsal heads, midfoot and heel. There is no post-hoc region selection and no indexing to either device. Contralateral thermal asymmetry (Delta T) is computed per region as the absolute difference in mean temperature between homologous regions of the right and left foot.
Images are renamed with an alphanumeric code that removes any explicit reference to the source device before analysis, and regions are delimited by an independent evaluator blinded to the neurological status of the participant. Technical blinding is acknowledged as partial, because the difference in spatial resolution between the two cameras may allow a trained evaluator to infer the source device.
The sample size follows the method of Walter, Eliasziw and Donner for the intraclass correlation coefficient, with a null hypothesis of ICC0 = 0.65 against an alternative of ICC1 = 0.80, alpha = 0.05, nominal power 0.80 and two observations per participant, which yields a minimum of 77 participants. The study enrolls 130 participants, which raises the actual power for this contrast to 95.7 percent and absorbs expected losses.
研究设计
- 研究类型
- Observational
- 观察模型
- Cohort
- 时间视角
- Cross Sectional
入排标准
- 年龄范围
- 18 Years 至 —（Adult, Older Adult）
- 性别
- All
- 接受健康志愿者
- 否
入选标准
- •Age 18 years or older.
- •Confirmed diagnosis of type 1 or type 2 diabetes mellitus.
- •Preserved plantar skin integrity at the time of the test.
- •Voluntary signature of the informed consent after receiving detailed information about the study.
排除标准
- •Active ulcers or open wounds in the plantar area, since exudation alters thermal emissivity.
- •Acute skin infection or extensive mycosis of the foot.
- •Previous partial amputation of the forefoot or midfoot that alters the anatomy of the regions of interest.
- •Severe peripheral arterial disease (Fontaine grade IV, critical ischemia) compromising tissue viability.
- •Physical or cognitive inability to remain in the semi-Fowler position (backrest 30 to 45 degrees) during the 15 minutes of the acclimatization protocol.
- •Intense physical activity or hydrotherapy within the 2 hours before the appointment, and caffeine intake or tobacco use within the same period, because of their vasoconstrictor effects.
- •Acute febrile state, body or tympanic temperature above 37.5 degrees Celsius at the time of the test.
- •Application of creams, moisturizing lotions, topical ointments or talcum powder to the plantar area within the 4 hours before the examination, because of the alteration of infrared emissivity and the evaporative cooling effect.
研究组 & 干预措施
Diabetes patients
Adults with diagnosed type 1 or type 2 diabetes mellitus, without active plantar ulceration, recruited from the active caseload of general podiatry and physiotherapy consultations.
干预措施: HIKMICRO® Mini2 V2 (Device)
Diabetes patients
Adults with diagnosed type 1 or type 2 diabetes mellitus, without active plantar ulceration, recruited from the active caseload of general podiatry and physiotherapy consultations.
干预措施: HIKMICRO® M60 (Device)
结局指标
主要结局
Intraclass correlation coefficient for absolute agreement, ICC(A,1), between the two cameras for contralateral thermal asymmetry (Delta T) in each of six pre-specified plantar regions of interest
时间窗: Single measurement session (Day 1)
Delta T is computed per region as the absolute difference in mean temperature between homologous regions of the right and left foot. One ICC(A,1) is reported for each of the six regions defined a priori (hallux, first, third and fifth metatarsal heads, midfoot and heel), with its 95 percent confidence interval, using the McGraw and Wong (1996) formulation, equivalent to ICC(2,1) of Shrout and Fleiss (1979), two-way random effects, single measurement. Each region contributes 130 paired measurements. The study hypothesis is ICC greater than or equal to 0.80, tested against a null of ICC0 = 0.65. Neither device is treated as a reference standard.
次要结局
- Cohen's Kappa for inter-device agreement in the binary classification of thermal asymmetry at the 2.2 degree Celsius cut-off, per region of interest(Single measurement session (Day 1))
- Consistency intraclass correlation coefficient, ICC(C,1), between the two cameras for mean plantar temperature (Tmean)(Single measurement session (Day 1))
- Bland-Altman systematic bias and 95 percent limits of agreement between the two cameras for mean plantar temperature (Tmean) and for contralateral thermal asymmetry (Delta T)(Single measurement session (Day 1))
- Influence of participant clinical variables on the magnitude of inter-device discordance(Single measurement session (Day 1))
- Image acquisition time(Single measurement session (Day 1))
- Proportion of technically valid thermograms(Single measurement session (Day 1))
- Participant acceptability of the measurement protocol(Single measurement session (Day 1))
- Descriptive distribution of the maximum contralateral thermal asymmetry per participant(Single measurement session (Day 1))
研究者
Eduardo Luis Martín Javier
Podiatrist, PhD Candidate
Universidad Europea de Canarias