Longitudinal investigation of ischemic stroke using magnetic resonance imaging: Animal model

Monitoring Progression of Diabetic Nephropathy Using T1- and T2-Weighted Imaging: An Animal Study

Purpose

Currently, diabetes and the consequent DN are considered a major public health issue. However, the mechanism of DN and its treatment require further clarification. This study proposed noninvasive T1-weighted (T1W) and T2-weighted (T2W) MRI protocols for the longitudinal assessment of kidney disease progression after DN induction in Sprague Dawley (SD) rats.

Methods

The changes in MRI image indices over time between control and DN SD rats were investigated. The volumes of the bilateral kidneys and the signals intensities (SIs) of the bilateral kidneys, renal pelvis, renal cortex, and renal medulla on turbo spin echo T1W and T2W images were obtained to observe DN progression in the rat kidneys.

Results

The results indicated that the edges of kidneys were clearer and sharper in the DN rats than in the control rats. The time-varying SIs of the bilateral whole kidneys, renal cortex, renal pelvis, and renal medulla on T1W and T2W images were significantly larger in the DN rats than in the control rats. Moreover, the volumes of both the left and right kidneys were significantly larger in the DN rats than in the control rats.

Conclusion

High-quality T1W and T2W images can be used to assess DN progression in SD rats’ kidney. Our results might be applicable to clinical routine diagnostic examinations that may improve diagnostic accuracy. Further development of the MRI technology for early DN detection and treatment is warranted.

An Optimal Animal Model of Ischemic Stroke Established by Digital Subtraction Angiography-Guided Autologous Thrombi in Cynomolgus Monkeys

Objective

Ischemic stroke seriously threatens human health, characterized by the high rates of incidence, disability, and death. Developing a reliable animal model that mimics most of the features of stroke is critical for pathological studies and clinical research. In this study, we aimed to establish and examine a model of middle cerebral artery occlusion (MCAO) guided by digital subtraction angiography (DSA) in cynomolgus monkeys.

Materials and Methods

In this study, 15 adult male cynomolgus monkeys were enrolled. Under the guidance of DSA, a MCAO model was established by injecting an autologous venous clot into the middle cerebral artery (MCA) via femoral artery catheter. Thrombolytic therapy with alteplase (rt-PA) was given to eight of these monkeys at 3 h after the occlusion. Blood test and imaging examination, such as computed tomography angiography (CTA), CT perfusion (CTP), brain magnetic resonance imaging (MRI), and brain magnetic resonance angiography (MRA), were performed after the operation to identify the post-infarction changes. The behavioral performance of cynomolgus monkeys was continuously observed for 7 days after operation. The animals were eunthanized on the 8th day after operation, and then the brain tissues of monkeys were taken for triphenyltetrazolium chloride (TTC) staining.

Results

Among the 15 cynomolgus monkeys, 12 of them were successfully modeled, as confirmed by the imaging findings and staining assessment. One monkey died of brain hernia resulted from intracranial hemorrhage confirmed by necropsy. DSA, CTA, and MRA indicated the presence of an arterial occlusion. CTP and MRI showed acute focal cerebral ischemia. TTC staining revealed infarct lesions formed in the brain tissues.

Conclusion

Our study may provide an optimal non-human primate model for an in-depth study of the pathogenesis and treatment of focal cerebral ischemia.