CT imaging of ovarian yolk sac tumor with emphasis on differential diagnosis.

Ovarian yolk sac tumors (YSTs) are rare neoplasms. No radiological study has been done to compare the imaging findings between this type of tumor and other ovarian tumors. Here we analyzed the CT findings of 11 pathologically proven ovarian YSTs and compared their imaging findings with 18 other types of ovarian tumors in the same age range. Patient age, tumor size, tumor shape, ascites and metastasis of two groups did not differ significantly (P > 0.05). A mixed solid-cystic nature, intratumoral hemorrhage, marked enhancement and dilated intratumoral vessel of two groups differed significantly (P < 0.05). The area under the ROC curve of four significant CT features was 0.679, 0.707, 0.705, and 1.000, respectively. Multivariate logistic regression analysis identified two independent signs of YST: intratumoral hemorrhage and marked enhancement. Our results show that certain suggestive CT signs that may be valuable for improving the accuracy of imaging diagnosis of YST and may be helpful in distinguishing YST from other ovarian tumors.

Experimental hypoxic-ischemic encephalopathy: comparison of apparent diffusion coefficients and proton magnetic resonance spectroscopy.

This study aims to compare the apparent diffusion coefficients (ADCs) and proton magnetic resonance spectroscopy ((1)H-MRS) in the first 24 h of acute hypoxic-ischemic brain damage (HIBD) in piglets. Twenty-five 7-day-old piglets were subjected to transient bilateral common carotid artery occlusion followed by ventilation with 4% oxygen for 1 h. Diffusion-weighted imaging (DWI) and (1)H-MRS were performed on cessation of the insult or at 3, 6, 12 or 24 h after resuscitation (all n=5). ADCs, N-acetylaspartate/choline (NAA/Cho), NAA/creatine (NAA/Cr), lactate/NAA (Lac/NAA), Lac/Cho and Lac/Cr were calculated. Cerebral injury was evaluated by pathological study and Hsp70 immunohistochemical analysis. On cessation of the insult, ADCs, NAA/Cho and NAA/Cr reduced, Lac/NAA, Lac/Cho and Lac/Cr increased. From 3 to 12 h after resuscitation, ADCs, Lac/NAA, Lac/Cho and Lac/Cr recovered, NAA/Cho and NAA/Cr reduced. Twenty-four hours after resuscitation, ADCs reduced once more, Lac/NAA, Lac/Cho and Lac/Cr increased again, whereas NAA/Cho and NAA/Cr decreased continuously. Pathological study revealed mild cerebral edema on cessation of the insult and more and more severe cerebral injury after resuscitation. No Hsp70-positive cells were detected on cessation of the insult. From 3 to 12 hours after resuscitation, Hsp70-positive cells gradually increased. Twenty-four hours after resuscitation, Hsp70-positive cells decreased. Throughout the experiment, changes in NAA/Cho and pathology had the best correlation (R=-0.729). In conclusion, NAA/Cho is the most precise ratio to reflect the pathological changes of early HIBD. Transient ADCs and Lac ratios recovery do not predict the reversal of histological damage of early HIBD. Reducing astrocytic swelling is of great clinical significance.