When a patient with head and neck cancer needs surgery to remove it, reconstructive surgery is often needed in the form of a “free flap”, skin and tissue taken from another part of the body and connected to the blood vessels of the wound to be repaired.
This free flap method, called microvascular reconstruction, has a 10-40% risk of wound complications, requiring re-operation in 10% of cases. A Michigan Medicine study shows that early postoperative CT scans and MRIs can help predict whether a flap will fail, allowing surgeons to intervene earlier. The results are published in the American Journal of Neuroradiology†
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“All patients undergoing this procedure can be examined with non-invasive postoperative CT or MRI perfusion, and these two methods hold promise as accurate biomarkers for predicting free flap viability,” said Ashok Srinivasan, MD, FACRsenior author of the paper and neuroradiologist at the University of Michigan Health.
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“By seeing how much blood flows in and out of the tissue, we may be able to predict whether the flap will succeed and whether the patient can be discharged sooner, or it may tell us sooner that surgical intervention is needed to repair the valve. Radiologists have CT — and MRI perfusion with contrast used to look at blood perfusion in brain imaging for stroke or tumor, but no study has used them to look at free flaps early after a procedure.”
The UM program for head and neck cancer performs about 300 free flaps per year, with each of these patients staying in the hospital for about a week after surgery. The ability to predict which patients are safe for an earlier discharge would provide significant and immediate cost savings, says Matthew Spector, MDco-author of the article and ENT specialist at UM Health.
Currently, most surgeons use ultrasound to assess the viability of free flap reconstruction using techniques known as doppler and skin paddle. Those methods often fail to evaluate deeper aspects of the flap, or air and blood products interfere with visualization, affecting how well clinicians can analyze a flap’s viability, says Srinivasan, who is also a clinical professor of radiology. is at the UM Medical School.
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The team of researchers at UM Health analyzed 19 patients who had undergone successful free flap reconstruction, as well as five with wound failure, between January 2016 and mid-2018. They found that both CT and MRI perfusion techniques showed significant differences between the two patient groups.
Researchers were unable to compare the two methods with ultrasound techniques or with each other because of the small sample size. They hope to achieve those comparisons through a larger future trial.
“This pilot study shows that these models work because all areas of the flap can be assessed with CT and MRI, unlike doppler and skin paddle where some areas can be blind to evaluation,” said Yoshiaki Ota, MD, lead author of the paper. and a neuroradiology fellow at the University of Michigan Health. “We know that using CT and MRI can help shorten a patient’s hospital stay or avoid prolonged hospitalization, and now we need to look further into what is more effective and cost-effective.”
Other authors include: Keith Casper, MD, Chaz Stucken, MD, Kelly Malloy, MD, Remy Lobo, MD, Akira Baba, MD, Ph.D., all Michigan Medicine, and Andreea Moore, MD, Western Michigan University School of Medicine .
This work received funding from the American Society of Head and Neck Radiology under the William N. Hanafee, MD, Research Grant and from the Internal Seed Grant from the Department of Radiology at the University of Michigan.
Cited article: “Wound failure prediction in patients with head and neck cancer treated with free flap reconstruction: utility of CT perfusion and MR perfusion in the early postoperative period”, American Journal of Neuroradiology† DOI: 10.3174/ajnr.A7458
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