*4.10. Short Tau Inversion Recovery*

The short tau inversion recovery (STIR), is an inversion recovery sequence, which is a spin-echo sequence with a 180◦ preparation pulse to flip the longitudinal magnetization into the opposite direction. In this case, to generate an MR signal, the longitudinal magnetization is then converted to transverse magnetization through the application of a 90◦ pulse. The time between the change from 180◦ to 90◦, or inversion time in such sequences, is kept short, between 130 and 150 ms.

#### Breast

In a preliminary clinical experience, the usefulness of whole-body turbo STIR sequence was assessed to detect liver, brain, and bone metastases as a single examination in breast cancer patients, in alternative to conventional techniques. Seventeen patients with biopsy-proven breast cancer and suspected metastatic disease were included in this study and underwent both whole-body STIR-MRI and conventional imaging, such as MR brain imaging with spin-echo; T1 and T2-weighted CT and ultrasound scanning; and bone scintigraphy. Three patients were found to be free of metastases in both conventional and STIR imaging. In eleven out of seventeen patients, appendicular or axial skeletal metastases were identified, with a good correlation between findings in whole-body STIR and scintigraphy. Hepatic metastases were found in five patients using whole-body STIR, of which only three patients' finding correlated with CT and ultrasound findings. Metastases and brain abnormalities were found in four patients via both whole-body STIR and dedicated brain MRI. Therefore, this pilot evaluation, even if performed on a small cohort of patients, showed that STIR acquisition might represent an accurate, convenient, and cost-effective staging method during the long-term follow-up of breast cancer patients [165].

## **5. Conclusions**

Translational research must be supported by a real interdisciplinary, synergistic collaboration to avoid the inconveniences and ineffectiveness of the methods, in order to emphasize the benefits of patients in a robust translational application. In order for an experimental imaging methodology to be successfully translated into clinical practice, it must have a substantial and immediate impact on application to the patient, and therefore, be easily accessible. The development and use of

animal models of cancer and its integration with molecular imaging tools may enhance the clinical translatability of preclinical studies focused on the clinical implementation of MRI methodologies in the management of tumor diseases from the diagnoses to therapeutics' evaluations and follow-up monitoring. From that perspective, it should be borne in mind that there is not a single ideal mouse model that recapitulates all features of the human pathology. Hence, the development and choice of the appropriate model must comply with the experimental, or from a translational perspective, with the direct clinical needs. Thus, it is fundamental to evaluating which the characteristics that may influence clinical efficacy are; i.e., histopathologic features, immune system interaction, carcinogenesis, angiogenesis, tumor progression, and metastatic potential. Indeed, as described, each model has its peculiarities, and all might be considered complementary to each other. Finally, the best combination of the appropriate experimental model and the careful choice of imaging modalities with clinical homologs might accelerate the reduction in the gap between preclinical and clinical studies. The high translational ability of MRI, among the other imaging techniques, due to the high similarity in terms of hardware and software between experimental and clinical scanners, should strengthen the efforts in evaluating how far this technique can go for the diagnosis and management of cancer patients.

**Author Contributions:** M.F.F. searched for literature and drafted the manuscript; C.C. coordinated the research group and selected the papers to be included; L.A. revised the manuscript and formatted it for submission; L.B. wrote the technical parts in the manuscript; M.S. coordinated the research group and revised the manuscript.

**Funding:** This research was funded by "Ricerca Corrente", Italian Ministry of Health.

**Conflicts of Interest:** The authors declare no conflict of interest.
