Role of endorectal ultrasonography and CT in preoperative staging of rectal cancer. Personal experience]

We report our personal experience on endorectal US and CT in the preoperative staging of rectal carcinoma. Our series includes 64 cases (38 male and 26 female) evaluated with intrarectal sonography; 38 of these patients underwent also CT-study of the lower abdomen. Using both imaging techniques infiltration of the rectal wall and adjacent structures and lymph node involvement were studied. The results of our study refer to 58 patients who underwent endorectal US, 31 of whom studied also with CT. Referring to the T-parameter with ultrasound 41 correct diagnosis were obtained, in 13 cases the lesion was over-staged and in 4 cases understaged. The sensitivity, specificity and diagnostic accuracy was respectively 89.5%, 60% and 79.3%. With CT 23 diagnosis were correct, in 1 case the lesion was overstaged and in 7 cases understaged; sensitivity, specificity and diagnostic accuracy concerning rectal wall infiltration were respectively 72%, 83.3% and 74.2%. The evaluation of the N-parameter demonstrated low value of sensitivity with both US (15.8%) and CT (42.9%). Considering the results of our series, we feel that it is necessary to use both imaging techniques because results obtained are complementary referring to the T-parameter, although N-parameter were a little significant.     

Topotaxy between BaTiO3 and Ba6Ti17O40

The orientational relationship between intergrown lamellae of tetragonal (t) BaTiO₃ and monoclinic (m) Ba₆Ti₁₇O₄₀ was found to be ( 1 1 1 )_t||(001)_m, (001)_t||( 1 0 1 )_m, and [110]_t||[0 1 0]_m. On the basis of this relationship a model of a topotactic boundary between these two phases was constructed.