The radiologic appearance of intercostal muscle flap

The intercostal muscle flap (ICMF) is commonly used in airway and esophageal surgery to reinforce an anastomosis or site of closure. These flaps undergo heterotopic ossification that may result in stenosis of adjacent airways or the esophagus. We evaluated the computer tomography (CT) scan, technetium-99m-methylene diphosphonate bone scan and positron emission tomography with 2-[18F]-fluoro-2-deoxy-D-glucose (FDG-PET) findings of ICMF and the frequency of airway or esophageal stenosis.

A retrospective review was made of the radiologic records of 23 patients (9 women, 14 men) who underwent ICMF. The CT scans were obtained a mean of 36 months (range, 1 week to 58 months) after surgery and the size, morphology, and density of the ICMFs were recorded. Correlative bone scan in 13 patients and FDG-PET scans in 11 patients were reviewed.

A discontinuous, thin, linear calcified stripe or parallel stripes (mean thickness, 4 mm; mean density, 430 Houndsfield unit [HU]) were present in all patients on CT. The flap contained fat density (mean, -59 HU) in 18 patients and soft tissue density (mean, 41 HU) in 8 patients and measured about 1 cm in thickness. The appearance of ICMF is characteristic when the ossification extends from the posterolateral chest wall to an adjacent bronchial stump. There was no increased uptake on bone scan or FDG-PET scan. None of the patients had airway or esophageal stenosis.

The ICMF manifests on CT as a thin, linear calcified stripe or parallel stripes with central fat or soft tissue density. Airway stenosis due to ICMF is likely quite rare. We did not detect any airway stenosis.