Bone infarct-associated sarcoma detected on FDG PET/CT.

Secondary sarcomas arising on the background of a bone infarct are extremely uncommon. Based on the knowledge of classic imaging patterns, however, lesions like bone infarcts can be recognized during positron emission tomography/computed tomography studies, which are now being performed increasingly in cancer patients. We demonstrate the detection of this rare entity on positron emission tomography/computed tomography and its correlation on magnetic resonance imaging in a 56-year-old man with asymptomatic multifocal osteonecrosis secondary to steroid treatment for polymyositis.

Therapeutic response to radiofrequency ablation of neoplastic lesions: FDG PET/CT findings.

Ablation of neoplastic lesions by using radiofrequency energy is gaining popularity in clinical practice because of the minimally invasive nature of radiofrequency ablation (RFA). Primary and secondary tumors of the liver and lung are treated with RFA when surgery is precluded because of comorbidity. Benign bone tumors are also treated with RFA to relieve pain and prevent further tumor growth. Differentiation between postablation tissue changes and residual disease is difficult with morphologic imaging modalities such as ultrasonography, computed tomography (CT), and magnetic resonance (MR) imaging, thus limiting the use of these modalities to detection of residual disease early after RFA. Fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET) is a functional imaging modality that can be used to study the effects and efficacy of RFA. Lesions that show increased FDG uptake at PET become completely photopenic immediately after RFA, a finding that is suggestive of the completeness of ablation. Focal areas of increased FDG uptake within the ablated zone are suggestive of residual disease. Reactive tissue changes such as inflammation are depicted in the periphery of the ablated lesion and show a uniform low-grade FDG uptake, which can be differentiated from the focal, nodular intense uptake in areas of residual disease. Use of combined FDG PET/CT to detect residual disease early after RFA allows ablation to be repeated, if necessary, to obtain the maximum therapeutic benefit. Note that FDG uptake in the complications sometimes associated with RFA can be a cause of potential false-positive PET results.

Multiple FDG-avid sclerosing hemangiomas mimicking pulmonary metastases in a case of soft tissue sarcoma.

Non-neoplastic lesions have been known to mimic malignancies and metastases on positron emission tomography/computed tomography. We report the rare occurrence of multiple fluorodeoxyglucose-concentrating sclerosing hemangiomas in a patient with soft tissue sarcoma mimicking lung metastases.

Metastatic recurrence of an intracranial hemangiopericytoma 8 years after treatment: report of a case with emphasis on the role of PET/CT in follow-up.

Intracranial meningeal hemangiopericytomas are rare tumors that can mimic meningioma on imaging and on histopathology. However, these tumors are more aggressive with a tendency for local and metastatic recurrence, sometimes after a prolonged symptom-free interval. We report an unusual metastatic recurrence of an intracranial hemangiopericytoma, 8 years after surgery for the primary tumor and discuss the role of positron emission tomography/computed tomography in the follow-up of these patients.

PET/CT: Current status in India.

PET/CT is a new modality with integration of PET and CT systems. In India, since December 2004 there has been a steady increase in the number of imaging systems. From stand-alone PET/CT systems with on-site cyclotrons, mostly in the government sector, the modality has matured to such an extent that, today, the majority of the PET/CT scanners and cyclotrons are in the private setup; also, scanners situated in different locations (and even different cities) share the isotope produced from one cyclotron. This shows how much this field has developed and reflects the confidence of the end users. The current status of PET/CT in India is indeed healthy and heartening and the future certainly looks promising.