Advanced imaging modalities: advantages and disadvantages in their use with cardiopulmonary sarcoidosis.
| Uses and advantages | Disadvantages |
|---|---|
| CT > Standard for identification of lung parenchymal disease, mediastinal, hilar and paratracheal lymphadenopathy and can help identify high-yield sites for biopsy. > LGE with ECG-gated CT may be of benefit in patients with suspected heart involvement and implanted devices (unable to undergo MRI).16 > CT plays a key role in a condition where sarcoidosis may mimic other diseases.17 Also of use with atypical chest radiograph appearances and in identifying complications of mycetoma and pulmonary hypertension. | LGE for characterisation of myocardial involvement less optimal compared to MRI. High radiation dose. |
| MRI > Enables characterisation of myocardium and identifies wall thinning and motion abnormalities.18 > Identifies supportive evidence of lymphadenopathy. > LGE identifies areas of inflammation and/or fibrosis and potentially smaller areas than seen on nuclear perfusion studies.19 > Demonstation of LGE may have a significantly adverse prognostic implication.20,21 | Prohibited in patients with implanted devices unless certified ‘MRI conditioned’. Sub-optimal for pulmonary assessment. |
| Nuclear isotope perfusion imaging > SPECT using gallium-67 or thallium-201. Gallium-67 is highly specific for lung, lymph node and cardiac sarcoidosis and may be used to monitor response to therapy.22 > Positron-emitting radiopharmaceuticals include those labelled with fluorine-18 or gallium-68. > All of the above can be combined with X-ray CT for more precise anatomical definition. > Myocardial perfusion scintigraphy with thallium-201, technetium-99 or rubidium-82 may be used to identify scarring and particularly useful when combined with evidence of inflammation.23 | Gallium-67 has a low sensitivity and a high radiation burden. |
| PET > Fluorine-18 labelled FDG uptake has a high sensitivity and specificity for detection of inflammatory damage from myocardial sarcoidosis.24 > Quantification of FDG activity improves diagnostic accuracy,25 allows assessment of disease progression26,27 and prognosis.28 |
CT = computerised tomography; ECG = electrocardiogram; FDG = 2-fluorodeoxyglucose; LGE = late gadolinium enhancement; MRI = magnetic resonance imaging; PET = positron emission tomography; SPECT = Single photon emission tomography.