Immunoglobulin G4-related disease (IgG4-RD) was not recognised as a systemic condition until 2003, when extra pancreatic manifestations were identified in patients with autoimmune pancreatitis. Since then, IgG4-RD has been described to involve virtually every organ system. It is highly responsive to immunosuppressants but can have detrimental effects if left untreated. Early recognition of the disease is, therefore, critical. The diagnosis of IgG4-RD is frequently challenging owing to its non-specific clinical manifestations, indolent nature and broad differential diagnoses. Although histopathological examination remains the cornerstone of diagnosis, imaging plays an important role in establishing extent of disease and identifying areas suitable for biopsy. ¹⁸F-Fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) has been demonstrated to be useful in assessing organ involvement, guiding biopsy and monitoring disease response. The ¹⁸F-FDG PET/CT scan is highly sensitive and able to evaluate multiorgan involvement in a single examination, a key advantage over conventional imaging modalities. A potential pitfall is its low specificity. As such, detailed knowledge of the imaging findings in IgG4-related disease is required to avoid misdiagnosis. This pictorial review aims to depict the diverse spectrum of imaging findings of IgG4-RD and the key imaging features to distinguish it from other important differential diagnoses.

Quantitative nuclear imaging techniques are in high demand for various disease diagnostics and cancer theranostics. The non-invasive imaging modality requires radiotracing through the radioactive decay emission of the radionuclide. Current preclinical and clinical radiotracers, so-called nuclear imaging probes, are radioisotope-labeled small molecules. Liposomal radiotracers have been rapidly developing as novel nuclear imaging probes. The physicochemical properties and structural characteristics of liposomes have been elucidated to address their long circulation and stability as radiopharmaceuticals. Various radiolabeling methods for synthesizing radionuclides onto liposomes and synthesis strategies have been summarized to render them biocompatible and enable specific targeting. Through a variety of radionuclide labeling methods, radiolabeled liposomes for use as nuclear imaging probes can be obtained for in vivo biodistribution and specific targeting studies. The advantages of radiolabeled liposomes including their use as potential clinical nuclear imaging probes have been highlighted. This review is a comprehensive overview of all recently published liposomal SPECT and PET imaging probes.

This article provides a brief overview of the current state of hybrid single-photon emission computed tomography/computer tomography (SPECT/CT) imaging in musculoskeletal infections. SPECT/CT imaging, compared with conventional planar study and SPECT alone, provides improved anatomic localization of infection and more accurate delineation of the extent of infection. This article emphasizes three clinical aspects where SPECT/CT is found to be most useful: differentiating between soft tissue and bone infections, assessing suspected infected sites with underlying structural bone alterations, and defining infective focus when complex anatomy is involved. The accurate assessment of site of infection is vital for selecting the most appropriate therapeutic strategy. Other advantages of SPECT/CT imaging such as reducing the inconvenience of combination planar studies, providing additional CT information, and increasing interobserver agreement are also discussed.