Evaluation of the Performance of Glomerular Filtration Rate Measurement Using CT Urography in Patients With a GFR Below 60 mL/Min/1.73 m²

NCT ID: NCT07042698

Last Updated: 2025-06-29

Basic Information

• Recruitment Status: NOT_YET_RECRUITING
• Clinical Phase: NA
• Total Enrollment: 70 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-07-15
• Study Completion Date: 2027-07-15

Brief Summary

Glomerular filtration rate (GFR), which is the main biomarker used in clinical practice to assess kidney function, is usually estimated from the serum concentration of endogenous markers such as creatinine and/or cystatin C. GFR estimation equations all share the disadvantage of imperfect accuracy due to non-GFR-related determinants of creatinine and cystatin C. When knowing the exact GFR value is necessary for clinical decision-making, measurement by clearance of an exogenous tracer is required. Various tracers are available, some of which are radioactive tracers (99mTc-DTPA and 51Cr-EDTA), while others are iodinated contrast agents (iohexol, iothalamate). GFR measurement procedures are time-consuming and require significant human resources (4 to 5 hours, or even 24 hours for plasma clearances at very low GFR values).Urinary clearance methods may be inaccurate in cases of inadequate voiding. Plasma clearance results may be inaccurate in cases of increased (overestimation) or decreased (underestimation) extracellular volume, low GFR (unless late sampling is performed), or glomerular hyperfiltration. Measuring tracers requires either warm labs for measuring radioactive markers or labs with HPLC (High Performance Liquid Chromatography) chains for iohexol, which are part of an external quality assurance program. The complexity and/or length of GFR measurement procedures, their cost, and laboratory constraints explain why measured GFR is underused in routine clinical practice. There is a critical need to develop GFR measurement methods that are simpler to implement, reliable across the entire GFR spectrum, and widely available. We have demonstrated that it is possible to measure GFR using 4-phase CT urography performed as part of the care of living kidney donor candidates (healthy individuals with normal GFR). The examination takes 10 minutes, requires no biological sampling, and is not subject to potential inaccuracies due to sodium overload or poor bladder emptying.

Detailed Description

Objective: To assess whether GFR measurement using 4-phase CT urography is reliable in patients with GFR below 60 ml/min/1.73 m², as compared with iohexol clearance (reference method): - Unbiased (mean difference between CT-measured GFR and iohexol clearance not different from zero). - and accurate: at least 50% and 80% of GFR values measured by CT urography within 10% and 20% of biological clearance values for iohexol clearance.

Method: Single-center interventional study. After performing a 4-phase CT urography (or 3-phase CT scan, with the addition of a 4th phase for research purposes), performed for clinical indications as part of the patient's care, and using iohexol as a contrast agent, patients will undergo a biological measurement of iohexol clearance, based on serum and urine samples taken over 4 periods of 1 hour, between 3 and 7 hours after the CT scan. No iohexol will be reinjected to measure GFR. The CT scan images will be segmented by the investigator to determine the CT-measured GFR.

The inclusion criteria are: - Patients older than 18 years of age - Having given written consent to participate in the study. - Patient referred to the medical imaging department of the Henri Mondor University Hospital for a 3-phase or 4-phase abdominal CT scan. - With an estimated GFR according to CKD-EPIcreat2009 < 60 ml/min/1.73m² - Hospitalized or outpatient. - Affiliated with French national health insurance.

The exclusion criteria are: - Patients with hip implants, due to artifacts that make quantification of the contrast agent in the bladder unreliable. - Lack of health insurance - Patients under legal protection.

Conditions

Kidney Diseases; Tomography; X-Ray Computed

Study Design

• Allocation Method: NA
• Intervention Model: SINGLE_GROUP
• Primary Study Purpose: DIAGNOSTIC
• Blinding Strategy: NONE

Study Groups

GFR Measurement Using 4-Phase CT Urography and Comparison with Iohexol Clearance

A study with one arm, adding experimental procedures to standard of care (a 4-phase CT urography and biological sampling) in order to evaluate the accuracy of GFR measurement by CT urography in patients with chronic kidney disease.

Group Type: OTHER

Glomerular Filtration Rate measurement with iohexol clearance

Intervention Type: OTHER

After performing a 4-phase CT urography (or 3-phase CT scan, with the addition of a 4th phase for research purposes), performed for clinical indications as part of the patient's care, and using iohexol as a contrast agent, patients will undergo a biological measurement of iohexol clearance, based on serum and urine samples taken over 4 periods of 1 hour, between 3 and 7 hours after the CT scan. No iohexol will be reinjected to measure GFR. The CT scan images will be segmented by the investigator to determine the CT-measured GFR.

Interventions

Glomerular Filtration Rate measurement with iohexol clearance

After performing a 4-phase CT urography (or 3-phase CT scan, with the addition of a 4th phase for research purposes), performed for clinical indications as part of the patient's care, and using iohexol as a contrast agent, patients will undergo a biological measurement of iohexol clearance, based on serum and urine samples taken over 4 periods of 1 hour, between 3 and 7 hours after the CT scan. No iohexol will be reinjected to measure GFR. The CT scan images will be segmented by the investigator to determine the CT-measured GFR.

Intervention Type: OTHER

Eligibility Criteria

Inclusion Criteria

• Patients older than 18 years of age
• Having given written consent to participate in the study
• Patient referred to the medical imaging department of the Henri Mondor University Hospital for a 3-phase or 4-phase abdominal CT scan
• With an estimated GFR according to CKD-EPIcreat2009 < 60 ml/min/1.73m²
• Hospitalized or outpatient
• Affiliated with French national health insurance

Exclusion Criteria

• Patients with hip implants, due to artifacts that make quantification of the contrast agent in the bladder unreliable
• Lack of health insurance
• Patients under legal protection.

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

Assistance Publique - Hôpitaux de Paris

OTHER

Sponsor Role: lead

Responsible Party

Responsibility Role: SPONSOR

Locations

Assistance Publique Hôpitaux de Paris - CHU Henri Mondor - Créteil

Créteil, Île-de-France Region, France

Countries

France

Central Contacts

Thomas STEHLE, Dr

Role: CONTACT

thomas.stehle@aphp.fr

+33145178452

Facility Contacts

Thomas STEHLE, Dr

Role: primary

thomas.stehle@aphp.fr

+33145178452

Other Identifiers

APHP250438

Identifier Type: -

Identifier Source: org_study_id