Subtraction Perfusion CT: A Technical Note

It is challenging to attempt to obtain CT perfusion (CTP) images of the hyperdense tissues, which could conceal the density of contrast material during perfusion study. We report a new technique of subtraction CTP (SCTP) to compensate the shortcomings. SCTP post-processed by perfusion software for the data of post-perfusion images subtracting pre-perfusion corresponding images slice by slice in CTP source images is technically feasible without any adverse effects on patients. It provides a new functional imaging with quantitatively hemodynamic indexes of tissue microcirculation and reflects accurately the change of blood flow in tissues and organs.

Tubularized urethral reconstruction using a prevascularized capsular tissue prelaminated with buccal mucosa graft in a rabbit model

Tubularized graft urethroplasty fails largely because of in adequate graft take. Prefabricati on of buccal mucosa lined flap has theoretical in dications for con structi ng neourethra with an in depe ndent blood supply. The efficacy of using a tissue expander capsule as an in duced vascular bed to prefabricate an axial vascularized buccal mucosa-lined flap for tubularized urethral rec on struction in a rabbit model was tested. The experiments were performed in three stages. First, silicone tissue expanders were inserted into the groin to induce vascularized capsule pouch formation. Next, buccal mucosa grafts were transplanted to the newly formed capsular tissue supplied by the axial vessel for buccal mucosa-lined flap prefabrication. Then, circumferential urethral defects were created and repaired by buccal mucosa graft (Group 1), capsule flap (Group 2) and prefabricated capsule buccal mucosa composite flap (Group 3). With retrograde urethrography, no rabbits in Group 1 maintained a wide urethral caliber. In Group 2, the discontinued epithelial layer rege nerated at 1 month, and the con structed n eourethra narrowed eve n though the lume n surface formed in tact urothelial cells at 3 months. In Group 3, buccal mucosa formed the lining in the neourethra and kept a wide urethral caliber for 3 mon ths. The capsule may serve as an in duced vascular bed for buccal mucosa-li ned flap prefabricati on. The prefabricated buccal mucosa-lined flap may serve as a neourethra flap for circumferential urethral replacement.

Tissue expander capsule as an induced vascular bed to prefabricate an axial vascularized buccal mucosa-lined flap for tubularized posterior urethral reconstruction: preliminary results in an animal model

Surgical repair of complex posterior urethral disruptions remains one of the most challenging problems in urology.The efficacy of using a tissue expander capsule as an induced vascular bed to prefabricate axial vascularized buccal mucosa-lined flaps for tubularized posterior urethral reconstruction in a rabbit model was tested.The experiments were performed in three stages.First,silicone tissue expanders were inserted into the groin to induce vascularized capsule pouch formation.Next,buccal mucosa grafts were transplanted into the newly formed capsular tissue supplied by axial vessels for buccal mucosa-lined flap prefabrication.Then,circumferential posterior urethral defects were created and repaired with the buccal mucosa graft(Group 1),the capsule flap(Group 2),and the prefabricated capsule buccal mucosa composite flap(Group 3).After surgery,notable contracture of the tubularized buccal mucosa graft was observed in the neourethra,and none of the rabbits in Group 1 maintained a wide urethral caliber.In Group 2,the retrieved neourethra showed little evidence of epithelial lining during the study period,and the lumen caliber was narrowed at the 3-month evaluation.In Group 3,the buccal mucosa formed the lining in the neourethra and maintained a wide urethral caliber for 3 months.The capsule may serve as an induced vascular bed for buccal mucosa-lined flap prefabrication.The prefabricated buccal mucosa-lined flap may serve as a neourethra flap for posterior urethral replacement.