Ok, here's a partial free translation:
An Examination of the use of fMRT for diagnosing Transsexuality
The brains of anatomically male transsexuals, who identify as female, did not react as typical males do to visual erotic stimuli. In a study using functional MagnetoResonanceTomography(MRT) the reaction was instead typically female.
This work was performed by the University of Essen. 36 subjects were shown visually erotic films, while fMRT was used to study the reactions inside the brain. The study was performed co-operatively with the Klinik für Psychosomatik, and attempted to answer the question of whether fMRT could be used to diagnose Transsexuality, and especially to help in the decision to permit Sex Reassignment Surgery.
Twelve heterosexual men and twelve heterosexual women were examined, along with twelve anatomical males who identify as women. As Dr. Elke Gizewski stressed at the Röntgenkongreß in Berlin, it was already well-known from preliminary investigations of other groups that differences between men and women appear in fMRT when they are presented with erotic stimuli.
In men, the limbic system and upper regions of the hypothalamus, the amygdalae and the insular cortex were activated substantially more strongly. “We confirmed this finding in the comparison between the heterosexual men and women of our Cohort”, said Gizewski.
This specifically male activation of the limbic system was not found in the transsexual sample. Under fMRT, the pictures corresponded rather accurately to those of the female sample.
Radiologists can now confirm what transsexuals report - that they feel “trapped in the wrong body” - on the basis of the activation of the brain when presented with erotic stimuli. There is obviously a biological correlation with the subjective feelings.
I'm not sure that's wholly proven. I'd need comparison tests between Gay men, Lesbian women, and Gay, Straight and Lesbian Transsexuals (both FtoM and MtoF) too. It may be that the sample of transsexual women were all Hetero, none Lesbian. If so, it may only prove a biological basis for sexual preference, rather than gender as such.
But that in itself would be even more unacceptable to those who persecute us, and call us "mentally ill".