Recruiting

Imaging Techniques

Sponsor:

Washington University School of Medicine

Code:

NCT04339374

Conditions

Rectal Cancer

Colorectal Cancer

Eligibility Criteria

Sex: All

Age: 19+

Healthy Volunteers: Not accepted

Interventions

Photoacoustic imaging, photoacoustic microscopy

Endorectal photoacoustic imaging probe

Reader Performance

Study Details

Brief summary:

The purpose of this study is to demonstrate the functionality of a novel endorectal photoacoustic ultrasound imaging modality in humans with rectal cancer. The study involves testing a previously developed endorectal device to determine its ability to accurately assess rectal tumor response to preoperative treatment. Investigators hypothesize that a co-registered photoacoustic ultrasound endorectal device can significantly reduce unnecessary surgeries in rectal cancer patients with complete clinical response while maintaining high sensitivity in identifying those with residual cancer.

Conditions

Rectal Cancer

Colorectal Cancer

Study ID

NCT04339374

Start date

May 1, 2023

Status verified date

Feb, 2026

Completion date

Dec 31, 2028

Anticipated

Primary completion date

Dec 31, 2028

Anticipated

Eligibility Criteria

Eligibility Criteria

Sex: All

Age: 19+

Healthy Volunteers: Not accepted

Inclusion Criteria Patients:

  • Patients with any stage of rectal cancer undergoing surgical resection.
  • Age >18 years
  • Able to provide informed consent

Additional Inclusion Criterion for in vivo imaging (patients):

  • Lesion located within 15cm of the anal verge

Exclusion Criteria Patients:

  • Inability to provide consent
  • Collection of intraoperative specimen for frozen section analysis will disqualify patients from participation

Eligibility Criteria Readers:

  • Colorectal surgeons or radiologists who treat or interpret imaging regularly for patients with rectal cancer.

Study Design

Enrollment

90 participants

Anticipated

Allocation

Non randomized

Intervention Model

Parallel Assignment

Primary purpose

Other

Interventions and Outcome Measures

Arms

other: In vivo imaging

  • Patients with distal rectal lesions (benign or malignant tumors within 15cm of the anal verge) will be enrolled for the in vivo imaging portion of the study
  • Participation will include an intraoperative, in vivo evaluation of the tumor with a novel endorectal photoacoustic ultrasound probe. Following the induction of anesthesia, patients will undergo a 20-minute endorectal imaging evaluation performed by their colorectal surgeon. After imaging, the patient will then undergo standard-of-care surgical resection of the rectum. The resection specimen may then be imaged ex vivo as deemed necessary.
  • For this portion of the study, enrollment will be limited to a total of 86 participants

experimental: Reader Team

3 surgeons and 1 radiologist will be initially trained to grade lesions using the PAM/US image from the first set of 30 patients (Group 1). They will then use the PAM/US data to grade lesions obtained from the second set of 56 patients after initial training (Group 2).

Interventions

Photoacoustic imaging, photoacoustic microscopy

-Emerging technique in which a short-pulsed laser beam penetrates diffusely into a tissue sample, causing the release of acoustic waves due to a transient temperature rise -The transient acoustic waves, or photoacoustic waves, are then measured around the sample by US transducers -The resolution of the devices can be altered by changing the wavelengths of laser light and spectrum analysis of the receiver. In this manner, human colorectal pathology will be examined under multiple types of photoacoustic ranges (broadly termed photoacoustic microscopy and photoacoustic imaging). The study has two phases. In the second phase, the investigators will provide assessments of treated rectum based on clinical information and photoacoustic information after initial training.

Endorectal photoacoustic imaging probe

-An endorectal imaging device using coregistered photoacoustic and ultrasound imaging has been constructed. This probe is used to perform in vivo imaging among patients with rectal pathology intraoperatively.

Reader Performance

After initial training using Group 1 data, readers will classify lesions as non-clinical complete responders (non-cCR) or clinical complete responders (cCR) based on standard-of-care (SOC) information. Following PAM/US imaging, readers will reassess lesion status using PAM/US data. PAM/US model outputs will be generated for each patient and compared with reader assessments. For patients undergoing surgery, tumor regression scores from surgical specimens will be compared with reader assessments and model outputs. For patients under nonoperative surveillance, clinical response at 2-year follow-up will be compared with model outputs. The study will evaluate whether PAM/US assistance improves residual tumor detection in Group 2 patients. As the model is under development, it will be iteratively retrained and tested as new data become available.

Primary outcome measure

  • Number of patients that readers are able to diagnose with rectal cancer [ Time Frame: Approximately 15 minutes ]
  • Number of patients without surgery who cleared as cCR after 2-years of follow-up [ Time Frame: 2-years of follow-up ]

Central Contacts and Locations

Central contacts

William Chapman, Jr., M.D.

314-454-7177chapmanjr@wustl.edu

Locations

Washington University School of Medicine

Recruiting

St Louis, Missouri, United States, 63110

Contacts

William Chapman, Jr., M.D.

314-454-7177chapmanjr@wustl.edu

Principal Investigator:

William Chapman, Jr., M.D.

More Information

Sponsor

Washington University School of Medicine

Last update posted

Feb 12, 2026

Last verified

Feb, 2026

Keywords

  • Rectal cancer
  • Nonoperative management
  • Watch and wait
  • Complete clinical response

Trial information was received from ClinicalTrials.gov and was last updated on 2026-09-09. This information was provided to ClinicalTrials.gov by Washington University School of Medicine on 2026-02-12.