If a free flap phalloplasty is chosen, the feeding vessels must be confirmed to be intact by a vascular Doppler ultrasound examination. With the radial forearm flap, this is particularly important in patients who have had fractures of the upper limb or have scarring from previous suicide attempts. Doppler investigation of the vessels of the acceptor site is indicated to assess their patency and caliber in patients with previous abdominal surgery. In patients undergoing anterolateral thigh (ALT) flap phalloplasty, CT angiography is the state-of-the-art imaging modality for preoperative vascular mapping of the donor site [1]. The entire vascular tree supplying the flap is fully investigated from the femoral artery to the perforators. If the need arises, the acceptor site can also be studied with the same CT procedure (Fig. 37.2).

Perforators are then marked by using Doppler interrogation in the neighborhood of the points identified by CT [2]. Preoperative color Doppler sonography is valuable in identifying the location of the penetrating points and the suprafascial courses of skin perforators. It facilitates prefabrication of the urethra, assists in the design of the flap, prevents injury to skin perforators during elevation of the flap, and decreases the risk of flap necrosis.

Besides the evaluation of the perforators, preoperative MDCT provides also an accurate preoperative measurement of the subcutaneous fat tissue in the donor site which is necessary in order to allow an adequate patient and perforator selection and to determine the exact size of the flap [1].

Before sex reassignment surgery, preoperative breast imaging, either ultrasonography and/or mammography, is indicated according to age, if the patient meets the usual natal female requirements [3]. We routinely investigate the breast also during the workup for the subcutaneous mastectomy. Early after the mastectomy, imaging has a role in the assessment of postoperative complications, including hematoma, seroma, and abscess formation [3]. Imaging-guided drainage may be performed if clinically indicated. FtM transsexuals who have undergone bilateral subcutaneous mastectomy as part of sex reassignment surgery have dramatically decreased risk of breast cancer by nearly 90 % compared to women [4]. Although there remains a small possibility that breast cancer may develop in residual breast tissue, screening mammography is therefore not indicated.

For FtM transsexuals undergoing phalloplasty, the ability to void while standing is a high priority [5]. Unfortunately, the reported incidence of urological complications following urethral reconstruction is high in all series [1, 6]. For this reason, certain surgeons have even stopped reconstructing a complete neourethra [7, 8]. The most serious complications of urethral reconstruction are urethrocutaneous fistulas, stenoses, and strictures. Hair growth is a relatively common cause of germ proliferation in the neourethra and chronic inflammation. Urethrography is the imaging modality of choice to evaluate urethral abnormalities and is routinely performed before removal of the suprapubic catheter inserted during the operation to divert the urine (Fig. 37.3). Ultrasonography allows also evaluation of hair growth in the neourethra [9].