Four subjects had known extrapulmonary sarcoidosis (cardiac, two subjects; neurologic, one subject; skin, one subject). An example of cardiac involvement is shown in Figure 3. In the three noncutane-ous cases, 99mTc-DP scanning revealed intense uptake in the involved organs. There was no evidence of extrapulmonary activity in the remaining patients, all of whom lacked clinical evidence of extrapulmo-nary sarcoidosis.
This prospective pilot study demonstrates that 99mTc-DP scans are frequently positive in patients with sarcoidosis. Sites of 99mTc-DP uptake correlate closely with the results of both CXRs and PFTs. 99mTc-DP scans also appear to identify sites of extrapulmonary involvement in patients with sarcoidosis.
Traditionally, among nuclear medicine modalities, Ga-based imaging has been utilized in sarcoidosis. However, the role for Ga scanning remains controversial. For example, in a multicenter study of Ga scintigraphy involving > 600 subjects, nearly one in four patients with evident involvement seen by CXR had no Ga uptake in the thorax. Similarly, although some investigators have reported a correlation between activity seen on Ga imaging in the parenchyma and evidence of alveolitis determined by BAL, others have not been able to corroborate these observations.’ For the diagnosis of sarcoidosis, Ga has a sensitivity that ranges from 60 to 90%.8Д° On the other hand, Ga has a poor specificity. The lambda-panda pattern, considered by some to be classic for sarcoidosis, also may be seen in patients infected with HIV, rheumatoid arthritis, and Sjogren syndrome. In a study to assess the role for Ga in predicting prognosis, moreover, Mana et al reported that Ga imaging did not add to other readily available tools such as the CXR and serial PFTs. Because of these limitations, the role for Ga is limited. Currently, some authors recommend Ga scanning (1) as an alternative to biopsy in patients with CXRs exhibiting classic stage I disease, (2) as a diagnostic aid in patients who present with signs and symptoms of sarcoidosis but normal CXR findings (ie, stage 0 disease), and (3) as a means for identifying alternative sites to biopsy.
Figure 3. Top : axial images of the chest demonstrate diffuse, left ventricular increased 99mTc-DP uptake (arrow). Bottom: coronal images of the chest demonstrate diffuse left ventricular increased 99mTc-DP uptake (arrowheads).