COLOFLOW: Laser Speckle Contrast Imaging Versus Near-infrared Fluorescence Imaging With Indocyanine Green (COLOFLOW)

July 17, 2026 updated by: Joost R. van der Vorst, MD, PhD, Leiden University Medical Center
COLOFLOW is a prospective observational study investigating whether Laser Speckle Contrast Imaging (LSCI), a dye-free and objective perfusion imaging technique, corresponds with the currently used subjective assessment of indocyanine green (ICG) fluorescence during colorectal surgery. In approximately 30 patients undergoing elective colon or rectal resection with primary anastomosis, both imaging modalities will be performed intraoperatively. The surgeons will base their clinical decisions solely on standard ICG fluorescence imaging, while LSCI measurements are collected for research purposes and do not influence treatment. Postoperatively, quantitative ICG parameters will be analysed and compared with LSCI perfusion maps to determine whether objective ICG analysis improves agreement with LSCI over subjective interpretation alone. In addition, the study will evaluate the feasibility of using the PerfusiX-IGS LSCI system during open colorectal surgery and describe postoperative outcomes, including anastomotic leakage. The ultimate goal is to contribute to more objective and standardized perfusion assessment during colorectal surgery

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

Study Title: COLOFLOW: Quantified ICG Fluorescence versus Laser Speckle Contrast Imaging (LSCI) for Perfusion Assessment in Colorectal Surgery.

Background Anastomotic leakage is a serious complication after colorectal surgery, occurring in approximately 10-15% of patients and contributing substantially to postoperative morbidity and mortality. Surgeons increasingly use indocyanine green (ICG) fluorescence imaging to assess bowel perfusion during surgery, but interpretation remains largely subjective and the technique has limitations, including dye dependency and difficulties with repeated measurements. Laser Speckle Contrast Imaging (LSCI) is a dye-free, real-time imaging technique that provides objective perfusion maps and may overcome several of these limitations.

Aim The primary aim of the study is to determine how well subjective intraoperative ICG fluorescence assessment agrees with LSCI perfusion imaging when evaluating bowel perfusion at the planned anastomotic site during colorectal surgery.

Secondary aims are:

To evaluate the spatial agreement between postoperative quantitative ICG analysis and LSCI perfusion boundaries.

To assess the feasibility of using the PerfusiX-IGS LSCI system during open colorectal surgery.

To record clinical outcomes, including anastomotic leakage rates.

Study Design COLOFLOW is a prospective, single-centre, observational study conducted at the Leiden University Medical Centre (LUMC). No randomization, blinding, or intervention is performed. LSCI measurements are recorded for research purposes only and do not influence surgical decision-making.

Participants The study includes approximately 30 adult patients undergoing elective colon or rectal resection with creation of a primary anastomosis. This population corresponds to patients enrolled in the ongoing QUANTICOLON study.

Inclusion Criteria

Age ≥18 years. Elective colorectal resection with primary anastomosis. Ability to provide informed consent.

Exclusion Criteria

Palliative surgery. Poor intraoperative visualization. Conditions that substantially interfere with perfusion assessment.

Methods

During surgery:

The surgeon identifies the planned bowel transection site under white light. The bowel is exteriorized for imaging. The PerfusiX-IGS LSCI system records a perfusion map. Standard-of-care ICG fluorescence imaging is then performed and interpreted subjectively by the surgeon.

After surgery, ICG recordings are quantitatively analysed using dedicated software to derive perfusion parameters such as:

Time to fluorescence onset (T0) Time to peak intensity (Tmax) Maximum intensity (Imax) Maximum normalized slope Outflow area-under-the-curve measurements

A custom Python-based analysis is used to compare the location of perfusion boundaries identified by both imaging techniques.

Outcomes Primary Endpoint

Agreement between subjective ICG interpretation and LSCI perfusion mapping, assessed by:

Categorical agreement (adequate vs. inadequate perfusion). Spatial agreement between perfusion boundaries identified by both modalities.

Secondary Endpoints

Distance between quantitative ICG and LSCI perfusion boundaries. Feasibility and usability of the PerfusiX-IGS system. Success rate of obtaining calibrated image documentation. Thirty-day postoperative outcomes, including complications and anastomotic leakage.

Statistical Analysis Categorical agreement will be evaluated using Cohen's kappa coefficient, while spatial agreement will be assessed with Bland-Altman analysis. Secondary analyses will explore whether quantitative ICG measurements provide better agreement with LSCI than subjective assessment alone.

Ethical Considerations The study is classified as non-WMO (non-Medical Research Involving Human Subjects Act) because it introduces no intervention beyond standard care. LSCI is non-contact, non-invasive, and does not influence treatment decisions. Risks to participants are minimal and primarily related to the storage and handling of anonymized imaging data.

Conclusion COLOFLOW investigates whether objective, dye-free LSCI can serve as a reliable reference method for bowel perfusion assessment during colorectal surgery and whether postoperative quantitative analysis of ICG fluorescence can improve upon the current subjective interpretation of ICG imaging. The study aims to support the development of more standardized and objective perfusion assessment strategies that may ultimately help reduce anastomotic leakage.

Study Type

Observational

Enrollment (Estimated)

30

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Sampling Method

Non-Probability Sample

Study Population

The population for this study consists of adult patients undergoing elective colon or rectal resection with the creation of a primary anastomosis

Description

Inclusion Criteria:

  • Adults ≥18 years.
  • Undergoing elective colon resection with primary anastomosis.
  • Able to provide consent for postoperative analysis of intraoperative imaging

Exclusion Criteria:

  • Palliative surgery.
  • Factors that severely limit intraoperative visualization (per investigator judgement).

Conditions interfering with perfusion assessment (e.g., severe peripheral vascular compromise).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Agreement ICG vs LSCI
Time Frame: Periprocedural and day 0 (day of surgery)
the agreement between subjective ICG fluorescence assessment and LSCI perfusion imaging at the planned anastomotic site during colorectal surgery. This agreement will be evaluated in two ways: (1) categorical agreement, determining whether both techniques classify perfusion as adequate or inadequate, and (2) spatial agreement, assessing how closely the perfusion boundary identified by the surgeon using ICG corresponds to the perfusion boundary detected by LSCI.
Periprocedural and day 0 (day of surgery)

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Spatial Agreement
Time Frame: From surgery untill 30 days follow up
Spatial distance (in millimetres) between the quantitative ICG perfusion boundary and the LSCI perfusion boundary
From surgery untill 30 days follow up
Feasibility Laser Speckle Device
Time Frame: Peri-procedural (day 0)

the feasibility and usability of the PerfusiX-IGS LSCI system

Unit of Measure:

Successful acquisitions (%) Acquisition time (seconds) Technical failures (%)
Peri-procedural (day 0)
30-day postoperative clinical outcomes
Time Frame: Day 0 untill 30-days post operatively
Clinical outcomes and the occurrence of anastomotic leakage. The proportion of patients experiencing any complication and the distribution of Clavien-Dindo grades will be recorded. Incidence of anastomotic leakage within 30 days after surgery, defined according to standard clinical and/or radiological criteria as applied in routine clinical practice. The proportion of patients diagnosed with anastomotic leakage will be recorded.
Day 0 untill 30-days post operatively

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Leiden University Medical Center

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

August 1, 2026

Primary Completion (Estimated)

August 1, 2027

Study Completion (Estimated)

September 30, 2027

Study Registration Dates

First Submitted

July 14, 2026

First Submitted That Met QC Criteria

July 17, 2026

First Posted (Actual)

July 22, 2026

Study Record Updates

Last Update Posted (Actual)

July 22, 2026

Last Update Submitted That Met QC Criteria

July 17, 2026

Last Verified

July 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • COLOFLOW

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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