Switching MRI Modes Helps Pediatric Patients Without Sacrificing Diagnostic Accuracy
Diffusion tensor imaging can replace diffusion weighted imaging to shorten procedure time and ease children’s discomfort.
Urinary infections in children are very common and can lead to pyelonephritis, in which the infection spreads to the kidneys. If this happens, the child is at risk for permanent kidney damage. Ultrasound is often used to diagnose acute pyelonephritis, but its images do not provide very specific information. While CT scans are the most accurate, they expose children to ionizing radiation. MRIs can substantially increase diagnostic accuracy, and they can be performed without contrast dyes in children.
But MRIs are plagued by movement, especially breathing, and the kidneys move around significantly during respiration. To compensate, operators can use diffusion weighted imaging with respiratory triggering, which acquires images as the patient is breathing out. But this method can increase procedure time from 50 to 300 percent. Moreover, children cannot always breathe in a regular pattern during the procedure and are often crying.
Clinicians and radiologists do not want to prolong the stress on a sick child, so they are always looking for ways to shorten procedures. In a study reported in May in the journal Pediatric Radiology, researchers at University Hospital of Rouen and the Hôpital Privé de l’Estuaire in France tested whether acute pyelonephritis could be diagnosed correctly from diffusion tensor imaging instead of DWI. DWI requires respiratory triggering and two imaging sequences, while DTI allows free breathing and uses only one imaging sequence.
The researchers compared two datasets – one of DWI and one of DTI from 31 children assessed for pyelonephritis. Two readers reviewed both anonymized sets, and although agreement between reviewers was slightly lower for the DTI images, the difference was minor. And DTI shaved an average of three minutes off the MRI procedure while improving image quality. The researchers concluded that DTI could reliably replace DWI for pediatric MRIs in pyelonephritis diagnosis.