• Antibody-based radiolabeled probes enabled noninvasive cancer localization in vivo, with background suppression strategies such as simulated non-target compounds and subtraction to enhance target-to-nontarget signal. Across CEA-targeting antibodies and external photoscanning platforms, imaging utility and quantitative potential emerged [1] [4] [6] [9].

• Magnetic resonance imaging (MRI) and spectroscopy matured toward in vivo chemical shift imaging and rapid tissue mapping. From 3D Fourier methods to in vivo proton shift images and brain/metabolic studies, these works established MR as a noninvasive, chemically informative modality for cancer and brain biology [3] [2] [20] [19] [18].

• Fluorescence-based optical imaging advanced cancer detection, using hematoporphyrin derivative fluorescence, phycoerythrin conjugates, ratio imaging, and microspectrofluorometry to visualize cellular processes and tissue environments, offering highly sensitive, low-background contrast in cells and tumors [5] [11] [15] [17] [13].

• Radiopharmaceutical development for Positron emission tomography (PET) and single-photon imaging demonstrated diverse tumor and brain applications, including 99mTc-labeled polyphosphate bone imaging, 11C-methionine tumor PET, and fluorodopa studies, illustrating diagnostic capability and pharmacokinetic insights in vivo [10] [16] [14].

• Quantitative receptor imaging and autoradiography established objective mapping of receptor distributions and required standardization between standards and tissue, enabling reproducible quantification across experiments and modalities [12] [7].