[Radiologic differential diagnosis of inflammatory round pulmonary infiltrates in immunocompromised patients. A prospective study using CT and MRT].

In a prospective study we examined the diagnostic ranking of CT and MR in 52 immunocompromised patients with nodular pulmonary lesions and clinical suspicion of invasive pulmonary aspergillosis (IPA). For early diagnosis of IPA (clinical symptoms having existed for less than 10 days) the CT halo sign proved highly sensitive and specific. MRT showed at this time a comparatively high sensitivity but only low specificity that could not be improved upon after Gd-DTPA. At a later stage of the aspergillosis infection (clinical symptoms manifested for more than 10 days) MR identified aspergillus-specific lesions with on-target characteristics (marked enhancement of margins after Gd-DTPA) or the so-called "reverse" target phenomenon (T2-weighted sequences). Such lesions were never seen in the early stage of the disease in patients with nodular pulmonary lesions of different aetiology (pseudomonal or staphylococcal pneumonia).