Imaging & Diagnostics

Abdominal aortic aneurysm (AAA) screening uses a single bedside abdominal ultrasound to measure the maximum infrarenal aortic diameter; an aneurysm is defined as ≥3 cm. The 2019 USPSTF statement gives a Grade B recommendation for one-time screening in men aged 65–75 who have ever smoked (Grade C for never-smokers in the same age band, Grade D against routine screening in non-smoking women without family history). The recommendation is anchored by the UK Multicentre Aneurysm Screening Study (MASS), which showed a 48 percent relative reduction in AAA-related mortality at 10 years in invited men aged 65–74. Ultrasound is radiation-free, inexpensive and highly sensitive. Detected AAAs are followed by surveillance scans whose interval is set by diameter, with elective repair typically considered at ≥5.5 cm in men. In Germany, statutory health insurance has funded a single screening ultrasound for men aged 65 and older since 2018.

Brain MRI volumetrics uses structural magnetic resonance imaging to quantify the volume of specific brain regions — most notably the hippocampus, lateral ventricles and total grey- and white-matter — as well as cortical thickness across parcellated regions. Automated analysis pipelines such as FreeSurfer and the GPU-accelerated FastSurfer process T1-weighted images to generate normative deviation scores; larger ventricular volumes and reduced hippocampal or cortical thickness are established markers of accelerated brain ageing, with rates of atrophy increasing substantially after age 60. Cross-sectional population studies such as UK Biobank have mapped trajectories of regional volume loss against age, lifestyle factors and disease risk, enabling the concept of a 'brain age gap' — the difference between estimated brain age and chronological age — as a potential biomarker for neurodegenerative risk and cognitive resilience.

Cardiovascular magnetic resonance (CMR) is the reference standard for quantifying left- and right-ventricular volumes, ejection fraction and myocardial mass, because volumetric measurement does not rely on geometric assumptions. Beyond function, CMR characterises tissue: late gadolinium enhancement (LGE) maps focal scar and fibrosis, T1 and T2 parametric mapping quantify diffuse fibrosis and oedema, and the extracellular volume (ECV) fraction is calculated from pre- and post-contrast T1 with haematocrit. These techniques diagnose and risk-stratify ischaemic and non-ischaemic cardiomyopathy, myocarditis, cardiac amyloidosis, sarcoidosis and Fabry disease. CMR uses no ionising radiation; limitations include cost, scanner availability, gadolinium contraindications in advanced renal failure, and reduced image quality with arrhythmia or implanted devices. Standardised acquisition protocols are published by the Society for Cardiovascular Magnetic Resonance (SCMR).

Carotid intima-media thickness (CIMT) is the B-mode ultrasound measurement of the combined thickness of the intima and media layers of the common carotid artery wall, serving as a surrogate marker for subclinical atherosclerosis and vascular ageing. CIMT increases progressively with age and is elevated in the presence of traditional cardiovascular risk factors; population-based studies established associations with incident myocardial infarction, stroke and all-cause mortality, and it was incorporated into risk calculators in the early 2000s. However, subsequent meta-analyses (Lorenz et al., Lancet 2012) showed that CIMT progression did not improve prediction of clinical events beyond traditional risk factors, leading major cardiology guidelines to downgrade its routine clinical use. CIMT remains widely used in cardiovascular research as an outcome measure for intervention trials and in observational studies of accelerated vascular ageing.

Coronary CT angiography (CCTA) uses multi-detector computed tomography with intravenous iodinated contrast to produce three-dimensional images of the coronary arteries, enabling assessment of both luminal stenosis and plaque composition — including non-calcified, low-attenuation (lipid-rich) plaques that are not visible on unenhanced calcium scoring. In the SCOT-HEART randomised trial (n=4,146), CCTA-guided management reduced the composite of coronary heart disease death or non-fatal myocardial infarction by 41% over five years compared with standard care, partly through reclassification of risk and initiation of preventive therapy. Modern CCTA delivers effective radiation doses of approximately 1–5 mSv with iterative reconstruction, substantially lower than earlier protocols; CT-derived fractional flow reserve (CT-FFR) extends the examination to haemodynamic significance assessment without invasive catheterisation. CCTA differs from coronary artery calcium (CAC) scoring: CAC quantifies calcified plaque burden only, while CCTA reveals the full atherosclerotic plaque landscape including non-calcified disease.

Echocardiography is cardiac ultrasound performed transthoracically (TTE) or transesophageally (TEE) and is the most widely used cardiac imaging modality. It quantifies left ventricular ejection fraction (LVEF), chamber volumes and mass, evaluates valvular disease, and assesses diastolic function using mitral inflow (E/A ratio) and tissue Doppler (E/e' ratio). Speckle-tracking strain imaging derives global longitudinal strain (GLS), which detects subclinical systolic dysfunction earlier than LVEF and carries independent prognostic value in heart failure, cardio-oncology and valvular disease. It uses no ionising radiation and is portable, but image quality is operator-dependent and limited acoustic windows reduce reliability in roughly 10–20 percent of adults. Standardised acquisition and reporting follow joint ASE/EACVI chamber-quantification recommendations.

FibroScan (vibration-controlled transient elastography, VCTE) measures liver stiffness in kilopascals (kPa) by propagating a low-frequency shear wave through hepatic tissue and tracking its velocity via ultrasound, with stiffer tissue reflecting more advanced fibrosis. Validated cut-offs range from approximately 7–8 kPa for significant fibrosis (F2) to >12–14 kPa for cirrhosis, though values are influenced by inflammation, congestion, food intake and BMI. In metabolic dysfunction-associated steatotic liver disease (MASLD, formerly NAFLD) — now the commonest cause of chronic liver disease globally — VCTE is endorsed as a non-invasive alternative to biopsy for fibrosis staging and longitudinal monitoring, avoiding both sampling error and procedural risk. The controlled attenuation parameter (CAP), measured simultaneously on modern devices, quantifies hepatic steatosis in dB/m and enables a single-visit assessment of both fat content and fibrosis stage.

Annual low-dose chest CT (LDCT) screens current and former heavy smokers for early-stage lung cancer at an effective dose of roughly 1–2 mSv. The pivotal US National Lung Screening Trial (NLST) showed a 20 percent relative reduction in lung-cancer mortality versus chest radiography; the Dutch–Belgian NELSON trial confirmed a 24 percent reduction in men at 10 years. The 2021 USPSTF recommendation (Grade B) covers adults aged 50–80 with a 20 pack-year history who currently smoke or quit within 15 years. In Germany the Bundesumweltministerium issued the Lungenkrebs-Früherkennungs-Verordnung in July 2024, the G-BA passed the corresponding Richtlinie in June 2025, and roll-out as a statutory health-insurance benefit is expected from April 2026 for ages 50–75 who have smoked for at least 25 years with ≥15 pack-years and who currently smoke or quit within the past 10 years. Known harms include false positives, incidentalomas and overdiagnosis; structured Lung-RADS reporting limits unnecessary work-up.

Mammography is low-dose X-ray imaging of the breast (effective dose roughly 0.4 mSv per bilateral two-view study) and is the only modality with randomised-trial evidence for reducing breast-cancer mortality. The 2024 USPSTF recommendation (Grade B) advises biennial screening for women aged 40–74, lowered from age 50, citing CISNET modelling that earlier initiation reduces mortality and narrows racial disparities. Evidence for screening women aged 75 and older, and for supplemental ultrasound or MRI in dense breasts (BI-RADS C/D), remains Grade I (insufficient). The German Mammographie-Screening-Programm offers biennial screening to women aged 50–75 (the upper limit was raised from 69 to 75 on 1 July 2024 following a G-BA/IQWiG benefit assessment). Harms include false positives, overdiagnosis (particularly DCIS) and radiation-induced cancer at very low absolute risk.

Magnetic resonance spectroscopy (MRS) uses the chemical-shift information in the MR signal to quantify tissue metabolites non-invasively, typically from a single voxel or a multi-voxel grid acquired on a standard MRI scanner. Brain 1H-MRS measures N-acetylaspartate (NAA, a marker of neuronal integrity), choline, creatine, lactate, myo-inositol, glutamate/glutamine and reduced glutathione; these are useful in tumour grading, mitochondrial disease, multiple sclerosis and neurodegenerative research. In the liver, MR proton density fat fraction (MR-PDFF), a chemical-shift-encoded MRI technique conceptually related to MRS, is the most accurate non-invasive measure of hepatic steatosis and has become the imaging endpoint of choice in MASLD/MASH trials, with good correlation to biopsy steatosis grades. MRS uses no ionising radiation; limitations include long acquisition times, susceptibility to motion and B0 inhomogeneity, modest spatial resolution and the need for specialised post-processing.

Positron emission tomography with amyloid-targeting tracers — florbetapir, florbetaben and flutemetamol, all FDA-approved — allows in vivo visualisation of fibrillar amyloid-beta plaques, while second-generation tau PET tracers such as flortaucipir map neurofibrillary tangle burden and staging (Braak stages) in living patients. PET amyloid and tau status have become clinically actionable since 2023–2024, following the FDA approvals of lecanemab (Leqembi) and donanemab: both anti-amyloid antibody therapies require confirmed amyloid positivity for treatment eligibility, and tau PET staging increasingly informs prognosis and likely treatment benefit. Centiloid standardisation of amyloid PET allows cross-scanner and cross-tracer comparison, though reimbursement for diagnostic use remains limited in most healthcare systems. Effective doses are approximately 5–10 mSv per scan depending on tracer and attenuation-correction CT (amyloid tracers ~5–7 mSv, tau tracers up to ~9 mSv); radiation exposure and cost are relevant constraints for population screening applications.

Positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET), typically combined with low-dose CT for attenuation correction and anatomical co-registration (PET/CT), images regional glucose metabolism. The effective dose is roughly 5–10 mSv (~7 mSv for FDG alone plus the CT component). Established indications include initial staging and response assessment in lymphoma, lung, head-and-neck, oesophageal, colorectal, melanoma and many other cancers, detection of recurrence, evaluation of cardiac sarcoidosis and infection of prosthetic material, and differentiation of dementia subtypes (Alzheimer- versus frontotemporal-pattern hypometabolism). FDG is not specific for tumour cells – inflammation, infection and brown adipose tissue also avidly take up glucose – so false positives are common. FDG-PET is not validated as a routine longevity or whole-body screening test in asymptomatic adults because of the high incidentaloma rate, radiation exposure and cost. Standardised acquisition follows EANM procedure guidelines.

Pulse wave velocity (PWV) is the speed at which the pressure wave generated by ventricular ejection travels along the arterial tree, and is the non-invasive gold-standard measure of arterial stiffness. Carotid-femoral PWV (cf-PWV), measured by applanation tonometry or oscillometric devices over the aortic segment, is the most validated modality: the European Society of Hypertension threshold of >10 m/s in the context of hypertension identifies pathological aortic stiffness. Arterial wall composition, cross-linking of structural proteins, elastin fragmentation and vascular smooth-muscle tone all contribute to stiffness, which increases progressively with age and is further accelerated by hypertension, diabetes and chronic kidney disease. Large prospective studies and meta-analyses have demonstrated that cf-PWV independently predicts cardiovascular events and all-cause mortality beyond traditional risk factors, including in populations free of established cardiovascular disease.

Optical coherence tomography (OCT) of the retina generates micrometre-resolution cross-sectional images of retinal layers, enabling quantification of macular thickness, retinal nerve fibre layer (RNFL) thickness and ganglion cell layer volume, while fundus photography documents the retinal vasculature and optic disc. Because the retina shares embryological origin and vascular supply architecture with the brain, retinal parameters serve as proxies for central nervous system and systemic vascular health: RNFL thinning is an established marker of glaucoma and has been associated with Alzheimer's disease, multiple sclerosis and Parkinson's disease. Deep-learning algorithms trained on fundus images can estimate cardiovascular risk factors — including age, sex, blood pressure and HbA1c — directly from the image, and emerging 'retinal age gap' AI clocks predict mortality and morbidity beyond chronological age in large population studies. OCT angiography (OCTA) extends the examination to capillary-level flow mapping without dye injection, enabling assessment of foveal avascular zone geometry as a vascular health marker.

Dermoscopy (also called dermatoscopy or epiluminescence microscopy) uses a handheld lens at roughly 10× magnification with polarised or immersion light to visualise sub-surface pigment patterns and vascular structures invisible to the naked eye. A meta-analysis of clinical-setting studies showed dermoscopy improves the diagnostic odds ratio for melanoma by approximately 9- to 15-fold compared with naked-eye examination. Total body photography (TBP) creates a standardised baseline of all pigmented lesions and, combined with sequential digital dermoscopy, supports surveillance of high-risk patients (more than 50 atypical nevi, familial atypical multiple mole melanoma syndrome, prior melanoma). AI-augmented systems (FotoFinder, SkinVision, MoleScope) and convolutional neural networks have shown dermatologist-level sensitivity in research settings but their performance in routine practice is variable. The modality is non-invasive and radiation-free; limitations include operator training, lower accuracy in amelanotic or nail/acral lesions, and the unresolved trade-off between earlier diagnosis and over-biopsy.

Whole-body MRI (WB-MRI) acquires multi-station images covering the brain, neck, thorax, abdomen and pelvis without ionising radiation, enabling simultaneous assessment of soft tissue, organs and bone marrow in a single session lasting approximately 45–90 minutes. Its clinical utility is established in specific contexts — surveillance of hereditary cancer syndromes (Li-Fraumeni, BRCA2) and staging of multiple myeloma — but evidence for benefit in asymptomatic general-population screening is lacking; randomised trial data demonstrating reduced morbidity or mortality from commercial longevity-screening offerings are not available. Incidentaloma rates are high, with studies reporting clinically significant and minor incidental findings in 30–50% of asymptomatic subjects, creating a risk of diagnostic cascades involving further imaging, biopsy and unnecessary intervention. Major radiology and oncology societies have not endorsed WB-MRI for routine preventive screening outside of defined high-risk genetic populations.