Positron emission tomography-computed tomography in the management of lung cancer: An update

Abstract

This communication presents an update on the current role of positron emission tomography-computed tomography (PET-CT) in the various clinical decision-making steps in lung carcinoma. The modality has been reported to be useful in characterizing solitary pulmonary nodules, improving lung cancer staging, especially for the detection of nodal and metastatic site involvement, guiding therapy, monitoring treatment response, and predicting outcome in non-small cell lung carcinoma (NSCLC). Its role has been more extensively evaluated in NSCLC than small cell lung carcinoma (SCLC). Limitations in FDG PET-CT are encountered in cases of tumor histotypes characterized by low glucose uptake (mucinous forms, bronchioalveolar carcinoma, neuroendocrine tumors), in the assessment of brain metastases (high physiologic 18F-FDG uptake in the brain) and in cases presenting with associated inflammation. The future potentials of newer PET tracers beyond FDG are enumerated. An evolving area is PET-guided assessment of targeted therapy (e.g., EGFR and EGFR tyrosine kinase overexpression) in tumors which have significant potential for drug development.

Keywords: Lung cancer; PET-CT; restaging; solitary pulmonary nodule; staging.

Figure 1

A 43-year-old male with right lung mass on CT (a). PET (b) and PET-CT (c) images showed intense FDG uptake in the mass (SUVmax-12) along with an area of necrosis. A diagnosis of primary malignant lung mass was made. It was confirmed to be NSCLC on histopathology

Figure 2

A 52-year-old male with NSCLC of right lung. FDG PET-CT was done for staging. CT (a) showed enlarged right paratracheal node (arrow) which was FDG avid (SUVmax-9.2) on PET-CT (b). A diagnosis of nodal metastasis was made on PET-CT. However, this turned out to be tuberculosis at histopathology. Hence, results of FDG PET-CT for nodal staging should be confirmed with FNAC/biopsy to avoid false positives

Figure 3

A 61-year-old male with NSCLC of left lung. FDG PET-CT was done for staging. CT (a) and PET-CT (b) images showed a large liver metastasis (arrowhead). Also noted was a right adrenal nodule on CT which showed FDG avidity on PET-CT (arrow), suggesting adrenal metastasis

Figure 4

A 70-year-old male with adenocarcinoma of right lung, postpneumonectomy and adjuvant radiotherapy. He presented with bony pains. FDG PET-CT was done to rule out distant metastasis. On CT (a) images a sclerotic lesion was seen in left ilium (arrow). It showed mild FDG uptake on PET-CT (b) images, suggesting skeletal metastasis

Figure 5

A 49-year-old male, postsurgery and radiotherapy for left lung NSCLC. PET-CT was done 9 months later for restaging. CT (a) images showed mass lesion in the thorax with fibrotic changes in pleura. PET-CT (b) images showed intense FDG uptake (SUVmax-13) in the mass suggesting recurrent disease (arrow). No uptake was noted in the pleura suggesting post therapy changes

Figure 6

A 51-year-old male with right lung NSCLC with nodal metastasis. FDG PET-CT (a) showed primary lung lesions (arrow) with mediastinal nodal metastasis (bold arrow). He underwent three cycles of chemotherapy. Post therapy PET-CT (b) showed almost complete regression of primary lesion (arrow) but increase in size and uptake of mediastinal nodes (bold arrow). Also noted was appearance of new axillary nodal metastasis (arrowhead), suggesting progression of disease