Objective To assess the diagnostic value of ¹⁸F-fluorodeoxyglucose (FDG) micro-PET/CT in evaluating an intracerebral hemorrhage (ICH) model in rats in vivo.

Methods A simple random sampling method was used to select 32 healthy male adult SD rats, 4 of which were placed in the sham operation group and 28 rats were injected with 0.125 U/µL collagenase Ⅳ into the right basal ganglia to induce ICH (ICH model group). In the sham operation group, 0.9% saline was used instead of collagenase Ⅳ to make the sham model. The ICH model group was divided into seven groups by simple random sampling according to the time after ICH, which were 6, 24, 48 h and 3, 5, 7, 14 d (4 rats in each group). The sham operation and seven ICH model groups (6, 24, 48 h and 3, 5, 7, 14 d) underwent the neurological impairment scoring and ¹⁸F-FDG micro-PET/CT imaging. The hematoma volume at each time point in the ICH model group was calculated according to ¹⁸F-FDG micro-PET/CT imaging to delineate the region of interest (ROI) and Tada's formula. After imaging, the head was decapitated and the brain was obtained for hematoma observation and histopathological examination. The hematoma volume obtained by the two methods at the same time was compared by paired t-test and evaluated by Pearson correlation analysis.

Results In the sham operation group: the neurological impairment scores were zero; and micro-PET/CT clearly showed homogeneous ¹⁸F-FDG uptake in the brain tissue. The ICH model group: the neurological impairment scores were (2.21±0.30), (3.51±0.66), (2.83±0.20), (2.12±0.50), (1.44±0.37), (1.02±0.25) and (0.51±0.12) at 6, 24, 48 h and 3, 5, 7, 14 d after ICH, respectively. At each time point, the ¹⁸F-FDG uptake decreased or became defective in the right basal ganglia of the rat brain. The cerebral hematoma volumes evaluated by ¹⁸F-FDG micro-PET/CT were (24.05±3.00), (27.19±1.25), (25.58±1.57), (21.94±0.98), (19.88±1.53), (18.35±2.11) and (16.29±1.53) mm³, respectively. The cerebral hematoma volumes evaluated by Tada's formula were (23.17±1.93), (26.09±1.35), (24.64±1.95), (21.31±1.32), (19.07±1.64), (17.29±1.38), and (15.63±1.98) mm³, respectively. No significant difference in the hematoma volume was found between two methods at each time point in the ICH model group (t=1.18−3.06, all P>0.05). The cerebral hematoma volume obtained by the two methods was significantly positively correlated (r=0.99, P<0.001). After the dissection of the ICH model group, irregular hematoma formation was seen in the right basal ganglia of the brain tissue, which was opposite to the radioactive sparse and defective areas shown by ¹⁸F-FDG micro-PET/CT.

Conclusion ¹⁸F-FDG micro-PET/CT can accurately display the position, shape and size of the hematoma after ICH, and thus can be to verify the success of the rat ICH model in vivo.