Radiodiagnosis
Oncologic Imaging
Oncologic imaging for MBBS and NEET-PG: staging with CT and PET-CT, TNM, mammography, bone metastases and response assessment, mapped to NMC code RD1.8.
MedNext Academy | 3 min read
Oncologic Imaging
Oncologic imaging for MBBS and NEET-PG: staging with CT and PET-CT, TNM, mammography, bone metastases and response assessment, mapped to NMC code RD1.8.
This chapter covers the role of imaging across the cancer journey, from detection and characterisation to staging, biopsy guidance and response assessment. It teaches how CT, MRI, PET-CT, mammography and bone scanning are matched to the tumour type and the clinical question, framed by the TNM staging system.
High-yield: Oncologic Imaging
- Imaging in oncology serves screening, diagnosis, staging, treatment planning and monitoring of response to therapy.
- CT of the chest, abdomen and pelvis is the workhorse for staging most solid tumours and detecting metastases.
- The TNM system describes the primary tumour, nodal involvement and distant metastasis, and imaging maps each component.
- Positron emission tomography combined with CT uses fluorodeoxyglucose to show increased metabolic activity, valuable for staging lymphoma and detecting occult metastasis.
- MRI is preferred for local staging of rectal, prostate, cervical and many soft-tissue and brain tumours because of its soft-tissue contrast.
- Mammography is the screening modality for breast cancer, and suspicious microcalcifications and a spiculated mass raise concern for malignancy.
- Ultrasound complements mammography in dense breasts and distinguishes a cyst from a solid mass, and guides biopsy.
- The lung, liver, brain, bone and adrenal glands are common sites of haematogenous metastasis, and imaging targets these organs at staging.
- Lytic bone metastases are typical of many carcinomas, while sclerotic metastases are classic for prostate and treated breast carcinoma.
- A bone scan is sensitive for skeletal metastases and surveys the whole skeleton in one examination.
- Response to treatment is assessed by comparing tumour size on serial imaging using standardised response criteria.
- Image-guided biopsy under ultrasound or CT provides tissue for histological diagnosis with minimal invasiveness.
- The choice of the most appropriate and cost-effective imaging depends on the tumour type, its typical spread and the clinical question.
- Contrast enhancement helps characterise tumours and detect small nodal and visceral deposits at staging.
Imaging in cancer care
- **Staging:** CT chest, abdomen and pelvis for most solid tumours; MRI for local extent.
- **PET-CT:** Fluorodeoxyglucose uptake for lymphoma, occult metastasis and response.
- **Breast screening:** Mammography; microcalcification and spiculated mass are suspicious.
- **Bone metastasis:** Lytic in most carcinomas, sclerotic in prostate; bone scan surveys the skeleton.
NMC competencies in this chapter
- **RD1.8:** Radiological investigation and interpretation in common malignancies
Frequently Asked Questions
What is the role of PET-CT in cancer?
It combines the metabolic information of fluorodeoxyglucose uptake with the anatomical detail of CT, and is valuable for staging lymphoma, finding occult metastases and assessing response to treatment.
How is breast cancer screened for on imaging?
Mammography is the screening modality. Suspicious features include clustered microcalcifications and a spiculated soft-tissue mass, with ultrasound used to characterise lesions and guide biopsy, especially in dense breasts.
How do lytic and sclerotic bone metastases differ?
Lytic metastases destroy bone and appear as lucencies, typical of many carcinomas, while sclerotic metastases appear dense and are classic for prostate carcinoma and treated breast carcinoma.
How is treatment response assessed with imaging?
Serial imaging, usually CT, is compared using standardised response criteria based on change in tumour size and the appearance or disappearance of lesions, guiding continuation or change of therapy.
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