Table 1

Role of commonly used imaging modalities in the diagnosis and staging of patients suitable for radical treatment

Imaging modalityDiagnosisT stageN stageM stageComment
Chest x-rayOften included as part of initial investigation in primary care and useful to differentiate benign from malignant diseaseLimited information compared with MDCTProvides little informationObvious metastases may be visible (eg, lung or rib)Now sometimes omitted from investigation pathway if other presenting factors suggest cancer*
MDCTOften helpful to differentiate benign from malignant diseaseAble to measure tumour size accurately. Less reliable for distinguishing T3 from T4; 55% sensitivity, 89% specificity (axial CT)
  • Significantly enlarged nodes (>10 mm short axis) easily defined. However, about 40% of these are benign and 20% of nodes <10 mm are malignant.11

  • Sensitivity 57–61%, specificity 79–82%12 13

May show clear evidence of mediastinal invasion or metastatic disease but histological confirmation or further staging required if any doubtProvides excellent triage of patients by identifying clear evidence of cancer, no evidence of cancer ± other diagnoses or uncertainty. Guides the next test. May detect other significant coexistent disease
PET-CTNot currently performed for initial diagnostic purposesComplements MDCT and can help estimate tumour extent where tumour abuts abnormal tissue (eg, lobar collapse)More accurate than CT. Sensitivity 84%, specificity 89%. Further mediastinal sampling deemed unnecessary if PET negative and nodes <1 cm. 10% will have occult disease12Sensitivity and specificity to detect distant metastases 93% and 96%, respectively. May detect metastases in up to 15%. Sensitivity for brain metastases only 60%17–21Also useful in radiotherapy planning and may have a role in predicting outcome14–16
  • * Careful review of serial changes may help differentiate benign from malignant disease.

  • The prevalence of false negatives increases with later stage disease.

  • MDCT, multidetector computed tomography; PET-CT, positron emission tomography-computed tomographyc.