Influence of Fitzpatrick Skin Phototype and Body Mass Index on Non-invasive Optoacoustic Imaging

Influence of Fitzpatrick Skin Phototype and Body Mass Index on Non-invasive Optoacoustic Imaging of Muscle During Vascular Restriction and Physical Activity

Multispectral Optoacoustic Tomography (MSOT) is a promising imaging technology that utilizes pulsed laser light. While melanin content in the skin has been reported to influence light-based measurements in pulse oximetry and near-infrared spectroscopy, its effects on MSOT are not well understood. This proposed study aims to investigate how different Fitzpatrick skin phenotypes (FSP) and body mass index (BMI) influence muscle perfusion and oxygenation during arterial occlusion and muscle exercise over time. Healthy volunteers with varying skin tones (as defined by FSP) and BMI will be recruited and subjected to leg arterial occlusion and toe raise exercises. They will then be scanned on different body areas (arms and legs) to assess changes in muscle perfusion and oxygenation using MSOT.

Study Overview

• Status: Recruiting
• Conditions: Healthy
• Intervention / Treatment: Device: Multispectral Optoacoustic Tomography (MSOT)

Detailed Description

Melanin, a pigment found in the skin, has been reported to influence light-based measurements such as pulse oximetry or near-infrared spectroscopy (NIRS). Studies have shown measurements overestimation of darker skin tones or in ethnicities assumed to have darker skin tones compared to lighter skin tones. Even though optoacoustic imaging (OAI) has a different depth penetration than NIRS or pulse oximetry, the technology uses pulse laser light to assess tissue.

Multispectral Optoacoustic Tomography (MSOT) imaging is similar to conventional sonography: a transducer is placed on the skin, and instead of sound, energy is applied to the tissue by means of pulsed laser light. This leads to a constant change of minimal expansion and contraction of individual tissue components or molecules. The resulting sound waves can then be detected by the same device. Previous studies have already shown that the quantitative determination of hemoglobin can provide information on inflammatory activities or muscle hemodynamics. MSOT uses laser light between 660 and 1300nm to visualize and quantify different endogenous chromophores, such as hemoglobin, collagen, or melanin. Increase in melanin concentration (e.g. in melanomas or skin tags) has been previously assessed using the technology but never looked at signal at depth. Additionally, differences in body-mass-index (BMI) might influence light penetration, and therefore, the optoacoustic signal at depth. So far, no studies have looked at the influence of increased melanin concentration or subcutaneous fat on quantification of muscle perfusion and oxygenation.

In this first pilot study, the aim is to investigate the influence of different Fitzpatrick skin phenotypes (FSP) and BMI on muscle perfusion and oxygenation during arterial occlusion or muscle exercise and over time. This information is essential for further studies with a more diverse study population.

To gain insights into these differences, healthy volunteers with different skin tone (defined by FSP) and body-mass-index will be recruited and subjected to a leg arterial occlusion and to perform a toe raise exercise. They will then be scanned on different body areas (arm, legs) to assess changes in muscle perfusion and oxygenation by MSOT.

• Study Type: Observational
• Enrollment (Estimated): 130

Contacts and Locations

• Study Contact: Name: Felix Wachter; Phone Number: 09131 85 41175; Email: felix.wachter@uk-erlangen.de

Study Locations

• Germany
  • Bavaria
    • Munich, Bavaria, Germany, 81379
      • Recruiting
      • iThera Medical Headquarters
      • Contact: Charlene Reichl

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Eligible subjects are healthy volunteers who will be recruited from advertised announcements.

All subjects meeting all inclusion and none of the exclusion criteria will be enrolled.

Each healthy volunteer is categorized in 2 different groups based on his FSP and BMI:

1. FSP I, II, III, IV, V or VI, using the filled Fitzpatrick scale self-assessment questionnaire.
2. BMI<18.5 kg/m2, ≥ 18.5 and < 25 kg/m2 or ≥ 25 kg/m2, using the measured body weight and recorded body height.

Description

Inclusion Criteria:

• Signed informed consent

Exclusion Criteria:

• Pregnancy
• diagnosed diabetes
• diagnosed renal insufficiency
• diagnosed Peripheral arterial disease
• diagnosed muscle associated disease
• tattoos in scan area
• missing consent form

Study Plan

How is the study designed?

Number of groups / cohorts

9

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Fitzpatrick 1; Healthy volunteers with skin type 1.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
Fitzpatrick 2; Healthy volunteers with skin type 2.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
Fitzpatrick 3; Healthy volunteers with skin type 3.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
Fitzpatrick 4; Healthy volunteers with skin type 4.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
Fitzpatrick 5; Healthy volunteers with skin type 5.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
Fitzpatrick 6; Healthy volunteers with skin type 6.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
BMI Group 1; Healthy volunteers with BMI <18.5.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
BMI Group 2; Healthy volunteers with BMI >18.5 but <25.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.
BMI Group 3; Healthy volunteers with BMI >25.	Device: Multispectral Optoacoustic Tomography (MSOT); Non-invasive transcutaneous MSOT imaging of muscle regions.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Quantitative hemoglobin-associated signal (in arbitrary units)	Hemoglobin signal in the measured muscle regions in all different cohorts	immediately before and after intervention (occlusion and exercise)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Muscle oxygenation (in arbitrary units)	Oxygenated hemoglobin signal in the measured muscle regions in all different cohorts	immediately before and after intervention (occlusion and exercise)
Oxygen saturation (in %)	Proportion of oxygenated hemoglobin signal compared with total hemoglobin signal in the measured muscle regions in all different cohorts	immediately before and after intervention (occlusion and exercise)
Heart rate (in bpm)	heart rate of the healthy volunteers	immediately before and after intervention (occlusion and exercise)
Blood pressure (in mm Hg)	blood pressure of the healthy volunteers	immediately before and after intervention (occlusion and exercise)
Weight (in kg)	measured by body scale	baseline
Age in years	Participant questionnaire.	baseline
Gender: male, female, other	Participant questionnaire.	baseline
Skin tone based on Fitzpatrick questionnaire self-assessment (type 1-6, 1 being the palest, 6 being the darkest)	Participant questionnaire.	baseline
Dominant side	Participant questionnaire.	baseline
Sport frequency	Participant questionnaire.	baseline
Information on last physical exercise and caffeine and alcohol consumption	Participant questionnaire.	baseline
Quantitative collagen, lipid, water and melanin signal (in arbitrary units)	Signal in the measured muscle regions and the skin (melanin) in all different cohorts	immediately before and after intervention (occlusion and exercise)
Skin tone based on Fitzpatrick scale self-assessment (type 1-6, 1 being the palest, 6 being the darkest)	color card as reference	baseline
Skin tone based on Fitzpatrick scale examiner-assessment (type 1-6, 1 being the palest, 6 being the darkest)	color card as reference	baseline

Collaborators and Investigators

• Sponsor: University of Erlangen-Nürnberg Medical School
• Investigators: Principal Investigator: Ferdinand Knieling, PD Dr. med. habil., Department of Pediatrics and Adolescent Medicine, University Hospital Erlangen

Study record dates

Study Major Dates

• Study Start (Actual): June 14, 2024
• Primary Completion (Estimated): December 31, 2024
• Study Completion (Estimated): December 31, 2025

Study Registration Dates

• First Submitted: June 24, 2024
• First Submitted That Met QC Criteria: August 5, 2024
• First Posted (Actual): August 7, 2024

Study Record Updates

• Last Update Posted (Actual): August 7, 2024
• Last Update Submitted That Met QC Criteria: August 5, 2024
• Last Verified: June 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: cMSOT2-HV-01

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Raw data will be transferred to iThera Medical GmbH in anonymized form. iThera Medical GmbH is authorized to further transfer the anonymized data to the American Food and Drug Administration. The study results will be published anonymously in a scientific journal. Additionally, the raw data is planned to be published by the Friedrich-Alexander-University in an open-source manner to serve as reference standard. However it will not be possible to draw conclusions about the identity of the participating individuals.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: Yes
• product manufactured in and exported from the U.S.: No