Molecular Imaging

Molecular imaging encompasses a suite of non-invasive techniques that visualise, characterise and quantify biological processes at the cellular and molecular levels in living subjects. By exploiting targeted probes—ranging from fluorescent dyes and radiolabelled ligands to magnetic nanoparticles—these methods reveal early pathophysiological changes long before anatomical alterations become apparent. Key modalities include optical imaging (fluorescence and bioluminescence), nuclear techniques (PET and SPECT), magnetic resonance molecular imaging, ultrasound with targeted microbubbles and photoacoustic tomography. Each modality offers unique strengths: optical methods provide high sensitivity and real-time tracking; nuclear imaging yields quantitative whole-body maps of tracer distribution; MRI affords superb soft-tissue contrast without ionising radiation; ultrasound delivers bedside assessment of molecularly tagged microcirculation; and photoacoustics combines optical contrast with ultrasonic resolution at depth. Together, these approaches accelerate drug development, enable earlier diagnosis of cancer, cardiovascular, neurological and inflammatory diseases, guide targeted therapies and facilitate personalised monitoring of treatment response.

Research from Nature Portfolio

A fast all-optical three-dimensional photoacoustic tomography scanner has been reported that parallelises sensor readout and exploits compressed sensing to acquire volumetric vascular images within seconds. Depths approaching 15 mm are visualised with 100-μm resolution and 10 Hz frame rates, enabling dynamic assessment of tissue perfusion and inflammation in humans with minimal motion artefacts. This advance promises real-time clinical vascular imaging without ionising radiation.

Engineered small-molecule fluorophores for second near-infrared window (NIR-II; 1000–1700 nm) imaging have been developed by enhancing donor–acceptor interactions and preventing π–π stacking. These dyes emit beyond 1200 nm with signal-to-background ratios over 100 through 5 mm of tissue and exhibit ultralong crystallographic packing distances. Such bright NIR-II agents facilitate deep-lesion identification with near-zero background, advancing surgical guidance and tumour delineation.

Research from all publishers

A multimodal scanning fiber endoscope (SFE) has been introduced for intravascular angioscopy. Combining laser-induced autofluorescence and reflectance spectroscopy, the SFE delivers high-resolution morphological videos together with label-free biochemical maps of arterial plaques. This approach classifies vulnerable atherosclerotic lesions in real time and guides interventional strategies.

Hybrid PET/MRI using the short-chain fatty acid tracer [¹⁸F]fluoropivalate was shown to be safe and feasible in patients with lower- and higher-grade gliomas. Simultaneous PET and contrast-enhanced MRI acquisitions enabled quantification of tracer uptake kinetics and blood–brain barrier transport, distinguishing tumour grades and aiding biopsy guidance within a single imaging session.

Molecular Imaging publication trend

The graph below shows the total number of articles in molecular imaging across all publications each year (not limited to Nature Index journals).

Technical terms

Molecular imaging: Non-invasive visualisation of biological processes in vivo using targeted probes and high-sensitivity detection.

Contrast agent: A substance introduced into the body that enhances signal differences in imaging modalities, improving lesion detection and characterization.

Near-infrared II (NIR-II) window: The spectral region from 1000 to 1700 nm offering reduced scattering and autofluorescence for deep-tissue optical imaging.

Photoacoustic tomography: A hybrid imaging technique in which pulsed light absorption generates ultrasound waves that are reconstructed into high-resolution images of optical contrast.

Quantum yield: The efficiency of a fluorescent or luminescent probe, defined as the ratio of emitted photons to absorbed photons.

References

1. Multimodal Molecular Imaging: Current Status and Future Directions. Contrast Media & Molecular Imaging (2018).
2. A fast all-optical 3D photoacoustic scanner for clinical vascular imaging. Nature Biomedical Engineering (2024).
3. Engineered NIR-II fluorophores with ultralong-distance molecular packing for high-contrast deep lesion identification. Nature Communications (2023).
4. Feasibility of [18F]fluoropivalate hybrid PET/MRI for imaging lower and higher grade glioma: a prospective first-in-patient pilot study. European Journal of Nuclear Medicine and Molecular Imaging (2023).