Application of Multimodal Transcranial Ultrasound in SD Rats of Cerebral Ischemic Model at Super Early Stage

  Objective  To determine the value of applying multimodal ultrasound (mUS) in SD rats of cerebral ischemic model at super early stage (5-15 min after modeling).

  Methods  Fifteen focal cerebral ischemic models were established in SD rats with thinning skulls using the suture method. Gray-scale ultrasound, contrast-enhanced ultrasound, and enhanced color Doppler (CECDUS) were performed before and immediately after the modeling to observe the location of the in-cranial suture, perfusion of the right hemisphere, and color flow signal of the middle cerebral artery and the anterior cerebral artery, respectively.A modified neurological deficit score (mNSS) and 2, 3, 5-triphenyltetrazolium chloride (TTC) stains were obtained three hours later to confirm the successful modeling as the gold standard. The positive rate detected by mUS was compared with the gold standard using McNemar tests.

  Results  One rat died and 14 rats completed the experiment.mUS imaging detected 71% (10/14) positive signals, no significant difference compared with the gold standard (64%, 9/14) (P>0.05). A hyperechoic double-line at the bottom of the right brain and focal hypoperfused areas in the right hemisphere were observed by gray scale ultrasound and contrast-enhanced ultrasound in the successfully modeled rats, respectively. The CECDUS found no blood flow in the anterior and middle cerebral arteries. Time intensity curve (TIC) analyses indicated significant changes in peak intensity (PI), area under the curve (AUC), wash in slope (WIS), and time to peak (TTP) after successful modeling.

  Conclusion  Multimodal ultrasound can assess modeling success quickly and accurately immediately after the establishment of ischemic model of SD rats.