The diagnostic value of 18F-FDG-PET/CT in hematopoietic radiation toxicity: a Tibet minipig model

Imaging haemopoietic stem cells and microenvironment dynamics through transplantation

Understanding the subclinical pathway to cellular engraftment following haemopoietic stem cell transplantation (HSCT) has historically been limited by infrequent marrow biopsies, which increase the risk of infections and might poorly represent the health of the marrow space. Nuclear imaging could represent an opportunity to evaluate the entire medullary space non-invasively, yielding information about cell number, proliferation, or metabolism. Because imaging is not associated with infectious risk, it permits assessment of neutropenic timepoints that were previously inaccessible. This Viewpoint summarises the data regarding the use of nuclear medicine techniques to assess the phases of HSCT: pre-transplant homoeostasis, induced aplasia, early settling and engraftment of infused cells, and later recovery of lymphocytes that target cancers or mediate tolerance. Although these data are newly emerging and preliminary, nuclear medicine imaging approaches might advance our understanding of HSCT events and lead to novel recommendations to enhance outcomes.

Gut Microbial Compositions in Four Age Groups of Tibetan Minipigs

In this study, the gut microbiota was characterized in four age strata of Tibetan minipigs. Results indicated that the fecal bacteria of 7-, 28-, 56-, and 180-day-old minipigs did not significantly differ in terms of phylogenetic diversity (i.e., PD whole tree) or the Shannon index (both, p > 0.05). Findings of a principal coordinate analysis demonstrated that fecal bacteria of 180-day-old minipigs were discernable from those of the other three age groups. From ages seven to 56 days, the abundance of Bacteroidetes or Firmicutes appeared to vary. Regarding genera, the populations of Bacteroides and Akkermansia decreased with increasing age.

The diagnostic value of [18F]-FDG-PET/CT in assessment of radiation renal injury in Tibet minipigs model

BACKGROUND

Radiation-induced kidney damage can severely affect renal function, and have a serious impact on glucose reabsorption. Fluoro-2-deoxyglucose positron emission tomography (FDG-PET) is routinely utilized for metabolic imaging of glucose utilization. In this study, we are trying to assess the diagnostic value of ¹⁸F-FDG-PET/CT on measuring hyperacute effect of total body irradiation (TBI) on the kidneys.

METHODS

Forty-eight Tibet minipigs were treated by TBI of different dosages using an 8-MV X-ray linear accelerator. Whole-body ¹⁸F-FDG-PET/CT was performed at 6, 24 and 72 h followed by histologic examination, blood samples' and renal function analysis.

RESULTS

The uptake of ¹⁸F-FDG was significantly different between 11/14 Gy dose groups and control group, the standard Uptake Values reached a maximal level at 72 h after 14-Gy TBI treatment. At doses over 8 Gy, histological observation showed formation of tube casts, degeneration, necrosis of tubular cells, inflammatory cell infiltration and dilatation of the mitochondria of tubule cells. Renal function analysis confirmed the changes in blood urea nitrogen and creatinine levels at various dosages and time intervals. Immunohistochemistry and western blot results indicate that the expression levels of IL-10 and TNF-α proteins were positively correlated with radiation dose up to 8 Gy.

CONCLUSIONS

¹⁸F-FDG PET/CT can reflect pathological changes in kidneys and it may be a useful tool for rapid and non-invasive assessment in cases of suspected radiation-induced kidney damage.

The Use of Imaging in the Prediction and Assessment of Cancer Treatment Toxicity

Multimodal imaging is commonly used in the management of patients with cancer. Imaging plays pivotal roles in the diagnosis, initial staging, treatment response assessment, restaging after treatment and the prognosis of many cancers. Indeed, it is difficult to imagine modern precision cancer care without the use of multimodal molecular imaging, which is advancing at a rapid pace with innovative developments in imaging sciences and an improved understanding of the complex biology of cancer. Cancer therapy often leads to undesirable toxicity, which can range from an asymptomatic subclinical state to severe end organ damage and even death. Imaging is helpful in the portrayal of the unwanted effects of cancer therapy and may assist with optimal clinical decision-making, clinical management, and overall improvements in the outcomes and quality of life for patients.

Development of a minipig model for lung injury induced by a single high-dose radiation exposure and evaluation with thoracic computed tomography

Radiation-induced lung injury (RILI) due to nuclear or radiological exposure remains difficult to treat because of insufficient clinical data. The goal of this study was to establish an appropriate and efficient minipig model and introduce a thoracic computed tomography (CT)-based method to measure the progression of RILI. Göttingen minipigs were allocated to control and irradiation groups. The most obvious changes in the CT images after irradiation were peribronchial opacification, interlobular septal thickening, and lung volume loss. Hounsfield units (HU) in the irradiation group reached a maximum level at 6 weeks and decreased thereafter, but remained higher than those of the control group. Both lung area and cardiac right lateral shift showed significant changes at 22 weeks post irradiation. The white blood cell (WBC) count, a marker of pneumonitis, increased and reached a maximum at 6 weeks in both peripheral blood and bronchial alveolar lavage fluid. Microscopic findings at 22 weeks post irradiation were characterized by widening of the interlobular septum, with dense fibrosis and an increase in the radiation dose-dependent fibrotic score. Our results also showed that WBC counts and microscopic findings were positively correlated with the three CT parameters. In conclusion, the minipig model can provide useful clinical data regarding RILI caused by the adverse effects of high-dose radiotherapy. Peribronchial opacification, interlobular septal thickening, and lung volume loss are three quantifiable CT parameters that can be used as a simple method for monitoring the progression of RILI.

Longitudinal FDG-PET Revealed Regional Functional Heterogeneity of Bone Marrow, Site-Dependent Response to Treatment and Correlation with Hematological Parameters

PURPOSE

The purposes of this study were: 1) to show bone marrow (BM) functional heterogeneity, 2) to demonstrate site-dependent responses of BM to cancer treatment utilizing whole body FDG-PET/CT and 3) to identify correlations between FDG uptake in different bone sites and long term complete blood count (CBC).

METHODS

Thirty two patients who had pre- and post-treatment FDG-PET/CT scans were selected retrospectively. Each patient received either head and neck radiation for cancer of the tongue, or pelvic radiation for rectal or cervical cancer with chemotherapy. Patients had FDG-PET/CT performed prior to the first radiation therapy session and at least one FDG-PET/CT after completion of the prescribed radiation therapy.

RESULTS

FDG uptake before radiotherapy was significantly different among bone regions (p < 0.01). This heterogeneity was felt to reflect site-dependent amounts of BM contents possibly due to structural and functional requirements. FDG uptake in the irradiated regions was significantly decreased on the first and second follow-ups after radiation. Feasibly, this could be due to a reduction in the number of active BM cells following intensive radiation in addition to concurrent chemotherapy. Overall, CBC significantly decreased after treatment. Correlation values of each hematological parameter with FDG uptake varied among skeletal regions and scan time points. FDG uptake in sacrum and lumbar regions had better correlation with white blood cells and neutrophils.

CONCLUSIONS

Longitudinal FDG-PET revealed a regional functional heterogeneity of the BM site-dependent response to treatment. Patients experienced immediate and prolonged marrow metabolic damage that correlates with hematological parameters. FDG-PET/CT may provide additional capabilities to assess BM health.