Periantral soft-tissue infiltration and its relevance to the early detection of invasive fungal sinusitis: CT and MR findings.

PURPOSE Our goal was to illustrate the relevance of periantral soft-tissue infiltration to the early diagnosis of invasive fungal sinusitis and to describe variations in the appearance of normal periantral soft tissues. METHODS We reviewed two cases of pathologically proved invasive maxillary fungal sinusitis in which the sole imaging finding suggestive of invasive disease was periantral soft-tissue infiltration. Variations in the CT appearance of normal periantral soft tissues were studied in 112 patients by assessing the appearance of the fat planes along the anterior and posterior bony antral walls and by noting the presence of infraorbital and distal internal maxillary artery branch vessels within the anterior and posterior periantral fat planes, respectively. RESULTS None of the 112 patients had findings that suggested, or that could mimic, soft-tissue infiltration in the anterior periantral soft tissues. In only one (1%) of the 112 patients was there a loss of visibility of the posterior periantral fat plane that was not clearly attributable to the otherwise normal-appearing posterior periantral soft tissues. CONCLUSION Infiltration of the periantral fat planes may represent the earliest imaging evidence of invasive fungal disease. When encountered as the sole radiologic finding, periantral soft-tissue infiltration should suggest the possibility of invasive fungal sinusitis in the appropriate clinical setting.