Teaching pack: Imaging

Anatomic imaging (CT, MRI, ultrasound) shows shape and size. Functional and molecular imaging (PET, SPECT) shows biology: glucose uptake, receptor expression, immune cell presence. The frontier is target-specific PET that predicts whether a targeted drug will work, and imaging that reads out treatment response within days rather than months.

• AI in radiology: Software that reads scans alongside radiologists, catching cancers earlier and predicting who is at risk.
• Aidoc CARE (clinical radiology foundation model): Aidoc CARE is one radiology foundation model, pretrained on CT scans without labels, whose task-specific heads have each been FDA-cleared to flag urgent findings in emergency scans so radiologists read those first. Its oncology relevance is indirect, catching incidental masses; the regulatory evidence covers triage, not diagnostic accuracy for tumours.
• Biology-guided radiotherapy (RefleXion X1, SCINTIX): A radiotherapy machine with PET detectors built in: the tumour's own radioactive tracer signal tells the beam where to fire, hundreds of times a second, so moving tumours and several metastases can be tracked and treated without external markers.
• Breast cancer after chest radiotherapy in childhood, and the screening that follows: A girl who had radiotherapy to the chest carries a risk of breast cancer by age 50 of about 30 per cent. It is not only about dose: a low dose to the whole lung gave a higher standardised incidence than a high dose to a smaller field, because volume matters. Surveillance is recommended from early adulthood, decades before ordinary screening starts.
• Breast MRI coils and abbreviated breast MRI: Breast MRI is the most sensitive breast scan, done lying face down with the breasts in a special coil. Abbreviated protocols cut the scan from half an hour to a few minutes, which makes MRI screening of women with dense breasts or high risk affordable.
• CAIX PET (89Zr-girentuximab): CAIX PET is a scan using an antibody against a protein almost unique to clear-cell kidney cancer, to tell cancer from benign kidney lumps without a biopsy.
• Confocal microscopy and optical coherence tomography for skin (VivaScope, VivoSight, deepLive): Devices that look beneath the skin surface without cutting: one scans cells with a laser at microscope resolution, another builds a cross-section with infrared light. Both help decide whether a suspicious mole or patch needs a biopsy, and which edge to cut to.
• Contrast-enhanced mammography: A mammogram taken after an iodine contrast injection, at two X-ray energies, so that a tumour's blood supply shows up as a bright spot. It gives much of what breast MRI gives on a machine most breast units already own.
• CT (computed tomography): A CT scan is a fast 3D X-ray that shows the size and shape of tumours and whether they have spread.
• CT body composition and sarcopenia measurement: The staging CT scan every cancer patient already has can be measured for muscle and fat at the level of the third lumbar vertebra; low muscle predicts chemotherapy toxicity and shorter survival across cancers, and software now does the measuring automatically.

• Molecular imaging roadmap: FDG → PSMA → FAP → antigen and immune PET · PET and FDG (historic)
• Molecular imaging roadmap: FDG → PSMA → FAP → antigen and immune PET · Receptor PET: SSTR and PSMA (historic)
• Molecular imaging roadmap: FDG → PSMA → FAP → antigen and immune PET · Stromal PET and total-body scanners (current)
• Molecular imaging roadmap: FDG → PSMA → FAP → antigen and immune PET · Drug-target and immune PET (emerging)
• Molecular imaging roadmap: FDG → PSMA → FAP → antigen and immune PET · Speculative (speculative)
• Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch · A cancer is shown to depend on a hormone, and systemic cancer therapy begins (historic)
• Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch · A blood test arrives, and an epidemic of diagnoses follows it (historic)
• Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch · Does treating localised disease help? Three trials, three answers, one rule (historic)
• Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch · The screening trials disagree, and the policy swings twice (historic)
• Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch · Chemotherapy works, a little, and then the receptor drugs arrive (historic)
• Prostate cancer roadmap: from Huggins and the discovery that a cancer can depend on a hormone, through the PSA epidemic and what it cost, the androgen receptor drugs, the DNA repair subset and PSMA, to a 2032 registry watch · The genome: a quiet sequence, a rearranged structure, and one actionable fifth (historic)

• VISION (phase 3, n=861): Overall survival: 15.3 months vs 11.3 months, HR 0.62
• GHSG HD18 (phase 3, n=1,945): Progression-free survival at 5 years, scan-negative cohort: 92.2% vs 90.8%
• AHL2011 (phase 3, n=823): Progression-free survival at 5 years: 85.7% vs 86.2%, HR 1.084
• RATHL (phase 3, n=1,214): Progression-free survival at 3 years (PET2-negative): 85.7% vs 84.4%
• IELSG37 (phase 3, n=545): Progression-free survival at 30 months: 96.7% vs 98.5%
• TROG 99.03 (phase 3, n=150): Progression-free survival at 10 years: 59% vs 41%, HR 0.57

1. Does the TROP2 level measured on a biopsy tell you whether Trodelvy will work?
   Answer

   Not reliably. ASCENT showed benefit regardless of TROP2 IHC, so no companion diagnostic is required; expression is heterogeneous and archival tissue may not reflect current status. TROP2 PET tracers are being developed to map expression across the body and over time.
2. What is theranostics and what is the best-known example?
   Answer

   Using the same targeting molecule for a diagnostic scan and a treatment: PSMA PET shows where prostate cancer is, and 177Lu-PSMA-617 (Pluvicto) delivers radiation to the same target.
3. What did the VISION trial show?
   Answer

   177Lu-PSMA-617 plus standard care improved overall survival (15.3 vs 11.3 months, HR 0.62) in PSMA-positive metastatic castration-resistant prostate cancer after ARPI and taxane.
4. What is the difference between a CT scan and a PET scan?
   Answer

   CT is a fast 3D X-ray showing size and shape; PET shows biology by tracking where a radioactive tracer accumulates (for example glucose uptake with FDG or a specific protein such as PSMA). PET/CT combines both.
5. What does a FAPI PET scan see that an FDG scan often misses?
   Answer

   The activated fibroblasts (FAP) in tumour stroma, present in more than 90% of epithelial cancers, giving high contrast in pancreatic, gastric, HCC, and peritoneal disease where FDG is weak; it is not yet approved.
6. How could a TROP2 PET scan change how ADCs are used?
   Answer

   It would map antigen expression across all lesions and over time, potentially selecting patients, choosing between TROP2 ADCs, and detecting antigen loss at progression to guide a switch to a different target, as PSMA PET does for Pluvicto. First-in-human tracers exist; no outcome data yet.

• NCI: Cancer diagnosis, including imaging tests: https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis