Typical values of z-resolution for different Digital Breast Tomosynthesis systems evaluated in a multicenter study.

PURPOSE: The aim of the present study, conducted by a working group of the Italian Association of Medical Physics (AIFM), was to define typical z-resolution values for different digital breast tomosynthesis (DBT) models to be used as a reference for quality control (QC). Currently, there are no typical values published in internationally agreed QC protocols. METHODS: To characterize the z-resolution of the DBT models, the full width at half maximum (FWHM) of the artifact spread function (ASF), a technical parameter that quantifies the signal intensity of a detail along reconstructed planes, was analyzed. Five different commercial phantoms, CIRS Model 011, CIRS Model 015, Modular DBT phantom, Pixmam 3-D, and Tomophan, were evaluated on reconstructed DBT images and 82 DBT systems (6 vendors, 9 models) in use at 39 centers in Italy were involved. RESULTS: The ASF was found to be dependent on the detail size, the DBT angular acquisition range, the reconstruction algorithm and applied image processing. In particular, a progressively greater signal spread was observed as the detail size increased and the acquisition angle decreased. However, a clear correlation between signal spread and angular range width was not observed due to the different signal reconstruction and image processing strategies implemented in the algorithms developed by the vendors studied. CONCLUSIONS: The analysis led to the identification of typical z-resolution values for different DBT model-phantom configurations that could be used as a reference during a QC program.

Loss of the SHOX gene associated with Leri-Weill dyschondrosteosis in a 45,X male.

A male patient is reported with a 45,X karyotype and Leri-Weill dyschondrosteosis (LWD). FISH analysis with SHOX and SRY gene probes was carried out. One copy of both SHOX and SRY was detected in interphase nuclei, clarifying the origin of LWD and the male phenotype. Molecular results suggested that the 45,X karyotype arose through two independent events. The first occurred at paternal meiosis leading to an unequal crossing over between the short arms of the X and Y chromosomes. As a consequence, the SRY gene was translocated onto Xp, thereby explaining the male phenotype of the patient. The second event probably occurred at maternal meiosis or at the early stages of the zygote resulting in the loss of the maternal X chromosome.

Two newborns with chromosome 4 imbalances: deletion 4q33-->q35 and ring r(4)(pterq35.2-qter).

Two patients are reported who presented with 4q deletion and r(4), respectively. Cytogenetic and FISH analysis defined the breakpoints respectively at bands 4q33-->q35 proximal to the telomere, and 4pter and 4q35.2 qter. Moreover in both cases rearranged chromosomes maintained telomeric sequences. The first patient showed some clinical features of deletion 4q and a pointed 5th finger, a characteristic finding in deletion 4q31-->qter. The second patient had mild dysmorphism associated with growth retardation.

Characterization of the anti-stem cell activity of anti-mouse brain serum.

The anti-stem cell activity of a high-titer rabbit anti-mouse brain serum preparation has been further characterized. Following absorption with bone marrow and erythrocytes the antiserum had dose-dependent cytotoxicity against pluripotent stem cells. Rigorous absorptions with bone marrow, spleen, liver, erythrocytes, and thymus failed to remove the anti-stem cell activity of the serum. Adult brain, the immunogen, but not neonatal brain, removed a substantial amount of the activity against stem cells. Maximal cytotoxicity occurred both with and without complement and was maximal following only a 4 degrees C incubation of cells with serum. The anti-stem cell activity was present in the serum globulin fraction. No increase in the frequency of microcolonies or, with longer growth periods, in splenic macrocolonies was observed, suggesting that CFU-s were completely inactivated by exposure to the antiserum. Injected antiserum also reduced CFU-s in vivo.