IMAGING

Most imaging of fungal infection is done with plain chest radiology or CT scanning.

An increasing number of imaging investigations use MR, especially for the brain. Sometimes ultrasound is useful especially for cardiac echocardiography (endocarditis) and sometime direct visualization of fungi is possible down a bronchoscope (tracheobronchitis) or endoscope (oesphageal candidiasis or acute invasive fungal rhinosinusitis). Imaging is important for initial diagnosis and for following progress of infection over time. Simple enlargement of abnormal areas does not necessarily mean clinical failure, as enlargement can represent immune reconstitution, in some patients. View normal and abnormal CT and MRI scans.

Some radiology investigations are insensitive or unhelpful. These are listed below:

Disease 

Preferred investigation

Unhelpful investigation

Comment

Brain fungal infection

MR scan

Unenhanced CT scan of brain

CT scanning is insensitive and contrast often not given because of renal dysfunction. Unenhanced CT scan almost useless.

Lung fungal infection in leukaemia or after HSCT 

CT scan chest

Chest radiograph

Chest radiograph misses at least 10% of patients and is imprecise in the number and size of lesions

ABPA

CT scan chest

Chest radiograph

Chest radiograph is insensitive with respect to the complications bronchiectasis and chronic pulmonary aspergillosis

Fungal sinus disease

CT scan sinuses

Sinus radiograph

Sinus radiograph insensitive, especially for ethmoid and sphenoid disease 

Setting the correct parameters for CT and MR scanning requires radiological expertise. Likewise interpretation is critical and can be difficult. Radiological imaging cannot make a precise mycological diagnosis but usually contributes greatly to a full understanding of the extent of disease and its treatment. Mistaken radiological diagnosis does occasionally occur, primarily because a wide differential diagnosis is not considered initially, and some fungal infections are rare. 

Starkey J, Moritani T, Kirby P. MRI of CNS fungal infections: review of aspergillosis to histoplasmosis and everything in between. Clin Neuroradiol. 2014;24(3):217-30.