Dutch researchers have concluded that FDG-PET/CT can be a "sensitive tool," outperforming low-dose CT in determining the extent of bone involvement with sarcoidosis.
Researchers from Maastricht University Medical Centre in the Netherlands discovered a substantial number of sarcoidosis cases in the extremities using FDG-PET/CT, but a majority of those same lesions could not be detected by low-dose CT.
It's not known what causes sarcoidosis, which leads to inflammation in the extremities and can potentially affect any organ in the body. And it's also unclear how often bone involvement in sarcoidosis is present, said lead author Dr. Leonne Prompers, who presented study results at the Society of Nuclear Medicine (SNM) annual meeting last month.
"From previous literature, we think [incidence is] 2% to 3% of the patients, based mainly on morphologic or conventional imaging," she said. "The aim of our study was to examine the frequency and distribution pattern of bone involvement in sarcoidosis as detected by FDG-PET/CT."
The study included 123 patients who underwent FDG-PET/CT for severe sarcoidosis between June 2006 and September 2010, as well as a low-dose CT scan. All patients had unexplained disease-related disabling symptoms that persisted for at least one year and had sarcoidosis confirmed through biopsy.
The researchers excluded patients who suffered from other diseases that could cause a PET-positive finding. In the analysis of the 123 patients in the study sample, 94 (76%) had PET-positive findings associated with sarcoidosis. Subsequently, the 94 PET/CT scans were screened for the presence of bone or bone marrow localizations.
The researchers identified 32 patients (34%) with PET-positive bone or bone marrow localizations. Of those 32 patients, 19 (60%) also exhibited obvious focal bone lesions in a variety of locations.
"What is suggested in previous literature is bone lesions are predominately located in the extremities -- the fingers and the feet," Prompers noted. "What we saw was a lot of focal lesions in the whole skeleton, the axial skeleton, the pelvis, and the extremities."
Beyond extremities
The nonextremity lesions were found in the axial skeleton in 15 patients (47%), while 13 (40%) had lesions in their pelvis, 10 (34%) had lesions in their extremities, and one patient had a lesion in the skull.
Among 13 patients (40%), the researchers discovered large uptakes of FDG in both the axial and peripheral bone marrow, where no focal lesions were found. Both diffuse and focal uptake was seen in 11 patients (34%), while only focal lesions were detected in eight patients (25%).
"What is also quite interesting is that only two patients had lesions [detected] on their CT scans," Prompers added.
FDG-PET/CT-positive bone lesions were detected in one-third of patients in the study, Prompers and colleagues concluded. "That incidence is quite higher than expected, although this is somewhat of a selected population of patients who had severe complaints for more than one year," she added.
And while there was no single, most common location of the lesions, "I think we can say that PET is a potentially sensitive tool to detect bone marrow involvement," Prompers said.
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&fit=crop&h=100&q=70&w=100)
![Examples of ultrasound findings and techniques. (A) Images in a 39-year-old male patient with a mass in the left thigh. The mass is heterogeneous on the B-mode US image (compared with the patient in D) and showed increased microvascularity (superb microvascular imaging [SMI]) and shear-wave elastography (SWE) values. Undifferentiated pleomorphic sarcoma was diagnosed at biopsy (with pleomorphic rhabdomyosarcoma in surgical specimen). (B) Images in an 18-year-old male patient with a mass in the left leg. The mass is hypoechoic on the B-mode image, with no other findings suggestive of malignancy. The lesion is in contact with the cortex of the tibia, which is slightly irregular. CT revealed a doubtful anteromedial tibial erosion. The microvascular study demonstrated high vascularization, suggestive of malignancy. Periosteal Ewing sarcoma was diagnosed with both histologic and immunohistochemical confirmation. (C) Images in a 69-year-old female patient with a lump growing on the outside of the left leg. Multiple SWE examinations were performed (please note the high values obtained in the measurements, whereas the color map highlights the stiffness relative to adjacent tissues). SMI showed areas of increased vascularization to target for sampling. Undifferentiated spindle cell sarcoma was diagnosed at biopsy, with residual leiomyosarcoma in the surgical specimen after neoadjuvant therapy. (D) Images in a 56-year-old female patient with a mass in the right thigh. The mass is heterogeneous at both B-mode ultrasound (similar to patient A) and MRI (coronal T2-weighted spectral attenuated inversion recovery [SPAIR]; T1-weighted pre-contrast and postcontrast imaging), which even shows uptake after the administration of paramagnetic contrast material, which is traditionally suggestive of malignancy. Low values at SMI and elastography are suggestive of benignity. Spindle cell lipoma was diagnosed at biopsy, with atypical spindle cell lipomatous tumor in the surgical specimen.](https://img.auntminnieeurope.com/mindful/smg/workspaces/default/uploads/2026/08/images-radiol250278fig2.APCFLSvX6p.jpg?auto=format%2Ccompress&dpr=2&fit=crop&h=167&q=70&w=250)
