Pharmacokinetic analysis for the differentiation of pituitary microadenoma subtypes through dynamic contrast-enhanced...

The value of pharmacokinetic parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in distinguishing pituitary microadenoma subtypes was investigated in the present study. Pathology and follow-up outcomes were applied as the gold standard for differentiating between 76 patients with pituitary microadenomas (38 prolactin-producing tumors, 17 adrenocorticotropic hormone adenomas and 21 growth hormone-producing tumors) and 20 patients with normal pituitary glands. DCE-MRI was conducted to obtain the following quantitative permeability parameters: Volume transfer constant (K^trans), rate constant (K_ep) and extracellular extravascular volume fraction (V_e). Among the 76 cases included, 61 were visually diagnosed using conventional MRI. The K^trans, K_ep and V_e of the microadenoma cases were 0.472±0.292/min, 0.765±0.359/min and 0.792±0.345, respectively. The K^trans, K_ep and V_e of the normal control group were 0.902±0.238/min, 1.208±0.599/min and 0.928±0.378, respectively. The K^trans and K_ep of patients with microadenomas were significantly lower compared with those of the normal controls (P<0.05). However, the V_e of the two groups did not significantly differ. Subtype differentiation analysis revealed that patients with growth hormone-producing tumors exhibited the highest K^trans value (P<0.05). K_ep significantly differed between growth hormone-producing tumors and the other two subtypes (P<0.05), but did not significantly differ among three subtypes. Receiver-operator characteristic analysis indicated that the area under the curve values of K^trans and K_ep were 0.884 and 0.728, respectively. Sensitivity and specificity were 95.0 and 82.6%, respectively, when K^trans was set to 0.614/min as the cut-off value, and when the K_ep cut-off value was set to 0.985/min, sensitivity and specificity were 60.0 and 81.3%, respectively. In conclusion, K^trans and K_ep derived from DCE-MRI could be applied to detect and identify microadenoma subtypes. K^trans better reflects the blood perfusion alterations exhibited by patients with different microadenoma subtypes.