Small-Animal Molecular Imaging for Preclinical Cancer Research: μPET and μSPECT

Abstract

Due to different sizes of humans and rodents, the performance of clinical imaging devices is not enough for a scientifically reliable evaluation in mice and rats; therefore dedicated small-animal systems with a much higher sensitivity and spatial resolution, compared to the ones used in humans, are required. Smallanimal imaging represents a cutting-edge research method able to approach an enormous variety of pathologies in which animal models of disease may be used to elucidate the mechanisms underlying the human condition and/or to allow a translational pharmacological (or other) evaluation of therapeutic tools. Molecular imaging, avoiding animal sacrifice, permits repetitive (i.e. longitudinal) studies on the same animal which becomes its own control. In this way also the over time evaluation of disease progression or of the treatment response is enabled. Many different rodent models have been applied to study almost all kind of human pathologies or to experiment a wide series of drugs and/or other therapeutic instruments. In particular, relevant information has been achieved in oncology by in vivo neoplastic phenotypes, obtained through procedures such as subcutaneous tumor grafts, surgical transplantation of solid tumor, orthotopic injection of tumor cells into specific organs/sites of interest, genetic modification of animals to promote tumor-genesis; in this way traditional or innovative treatments, also including gene therapy, of animals with a cancer induced by a known carcinogen may be experimented. Each model has its own disadvantage but, comparing different studies, it is possible to achieve a panoramic and therefore substantially reliable view on the specific subject. Small-animal molecular imaging has become an invaluable component of modern biomedical research that will gain probably an increasingly important role in the next few years.

Radiomics in Breast Imaging: Future Development

“…Despite the limitations due to low spatial resolution, in the field of nuclear medicine, radiomics is developing as an equal to traditional radiology, taking advantage of the information functional that this can offer. In particular, in the radiomic scope, PET is the most promising test, and several studies suggested that PET acquisition radiomics analysis could provide a valid support in the diagnosis, staging, and characterization of various tumors [ 65 ].…”

The Role of Molecular Imaging in a Muscle-Invasive Bladder Cancer Patient: A Narrative Review in the Era of Multimodality Treatment

“…18 F-FDG PET/CT is the most common molecular imaging technique for preoperative staging of various malignancies, due to the higher metabolic rate of cancerous cells compared to normal ones [ 39 , 40 , 41 , 42 ], however, as a glucose analog, 18 F-FDG is excreted in urine and therefore it physiologically accumulates in the bladder, thus eventually masking the uptake of any superficial wall lesions and/or of the adjacent lymph nodes [ 43 ].…”

“…Although, only one not updated meta-analysis showed a pooled sensitivity of 0.82 and specificity of 0.89 for metastatic lesion detection [38]. 18 F-FDG PET/CT is the most common molecular imaging technique for preoperative staging of various malignancies, due to the higher metabolic rate of cancerous cells com-pared to normal ones [39][40][41][42], however, as a glucose analog, 18 F-FDG is excreted in urine and therefore it physiologically accumulates in the bladder, thus eventually masking the uptake of any superficial wall lesions and/or of the adjacent lymph nodes [43]. Intense glucose metabolism in the primary tumor higher than FDG urinary excretion is present (A).…”

Technical opportunities and challenges in developing total-body PET scanners for mice and rats

“…Because of the pathophysiological similarities between vertebrate mammals and humans, vertebrate mammals are widely used as models to study human disease and functions [1][2][3][4][5][6][7]. Mouse and rat comprise approximately 99.3% of mammals used in preclinical research in the USA [8].…”