Role of MRI and added value of diffusion-weighted and gadolinium-enhanced MRI for the diagnosis of local recurrence from rectal cancer

Purpose: To evaluate whether the addition of gadolinium-enhanced MRI and diffusion-weighted imaging (DWI) improves T2 sequence performance for the diagnosis of local recurrence (LR) from rectal cancer and to assess which approach is better at formulating this diagnosis among readers with different experience. Methods: Forty-three patients with suspected LR underwent pelvic MRI with T2 weighted (T2) sequences, gadolinium fat-suppressed T1 weighted sequences (post-contrast T1), and DWI sequences. Three readers (expert: G, intermediate: E, resident: V) scored the likelihood of LR on T2, T2 + post-contrast T1, T2 + DWI, and T2 + post-contrast T1 + DWI. Results: In total, 18/43 patients had LR; on T2 images, the expert reader achieved an area under the ROC curve (AUC) of 0.916, sensitivity of 88.9%, and specificity of 76%; the intermediate reader achieved values of 0.890, 88.9%, and 48%, respectively, and the resident achieved values of 0.852, 88.9%, and 48%, respectively. DWI significantly improved the AUC value for the expert radiologist by up to 0.999 (p = 0.04), while post-contrast T1 significantly improved the AUC for the resident by up to 0.950 (p = 0.04). For the intermediate reader, both the T2 + DWI AUC and T2 + post-contrast T1 AUC were better than the T2 AUC (0.976 and 0.980, respectively), but with no statistically significant difference. No statistically significant difference was achieved by any of the three readers by comparing either the T2 + DWI AUCs to the T2 + post-contrast T1 AUCs or the AUCs of the two pairs of sequences to those of the combined three sequences. Furthermore, using the T2 sequences alone, all of the readers achieved a fair number of \u201cequivocal\u201d cases: they decreased with the addition of either DWI or post-contrast T1 sequences and, for the two less experienced readers, they decreased even more with the three combined sequences. Conclusions: Both DWI and T1 post-contrast MRI increased diagnostic performance for LR diagnosis compared to T2; however, no significant difference was observed by comparing the two different pairs of sequences with the three combined sequences

Frequency noise performances of a Ti:sapphire optical frequency comb stabilized to an optical reference

We report on a detailed analysis of frequency noise and intensity dynamics of a free-running femtosecond Ti:sapphire optical frequency comb (OFC) pumped by a multi-mode 532nm laser.We have used these results for phase locking the OFC to a Hz-wide, cavity stabilized, 698nm semiconductor laser.An analysis of the in-loop error signals and an estimation of Allan deviation indicates a lower limit for the frequency stability of the OFC at the level of 5:3 10 14 for 125ms integration time comparable with the clock laser frequency stability over the entire OFC spectrum. The noise transfer processes between the pump laser and the Ti:sapphire laser have been studied in detail, comparing the resulting frequency noise of the OFC output spectrum with both a single-mode and a multi-mode pump lasers. In the latter case, we employed a pump beam steering control to maintain an OFC regime with a minimum impact of pump laser amplitude noise on the carrier-envelope offset frequency

Magnetic resonance imaging in locally advanced rectal cancer: Quantitative evaluation of the complete response to neoadjuvant therapy

Purpose: To assess the diagnostic performance of diffusion-weighted imaging (DWI) for the discrimination of complete responder (CR) from the non-complete responder (n-CR) in patients with locally advanced rectal cancer (LARC) undergoing chemotherapy and radiation (CRT). Material and methods: Between December 2009 and January 2014, 32 patients (33 lesions: one patient had two synchronous lesions) were enrolled in this retrospective study. All patients underwent a pre-and post-CRT conventional MRI study completed with DWI. For both data sets (T2-weighted and DWI), the pre-and post-CRT tumour volume (V T2 ; V DWI ) and the tumour volume reduction ratio ( 06V%) were determined as well as pre-and post-CRT apparent diffusion coefficient (ADC) and ADC change ( 06ADC%). Histopathological findings were the standard of reference. Receiver operating characteristic (ROC) curves were generated to compare performance of T2-weighted and DWI volumetry, as well as ADC. Results: The area under the ROC curve (AUC) revealed a good accuracy of pre-and post-CRT values of V T2 (0.86; 0.91) and V DWI (0.82; 1.00) as well as those of \u394V T2 % (0.84) and \u394V DWI % (1.00) for the CR assessment, with no statistical difference. The AUC of pre-and post-CRT ADC (0.53; 0.54) and that of \u394ADC% (0.58) were significantly lower. Conclusions: Both post-CRT V DWI and \u394V DWI % (AUC = 1) are very accurate for the assessment of the CR, in spite of no significant differences in comparison to the conventional post-CRT V T2 (AUC = 0.91) and \u394V T2 % (AUC = 0.84). On the contrary, both ADC and \u394ADC% values are not reliable

Optical detector topology for third-generation gravitational wave observatories

The third generation of gravitational wave observatories, with the aim of providing 100 times better sensitivity than currently operating interferometers, is expected to establish the evolving field of gravitational wave astronomy. A key element, required to achieve this ambitious sensitivity goal, is the exploration of new interferometer geometries, topologies and configurations. In this article we review the current status of the ongoing design work for third-generation gravitational wave observatories. The main focus is the evaluation of the detector geometry and detector topology. In addition we discuss some promising detector configurations and potential noise reduction schemes

Rapid disease progression in HIV-1 perinatally infected children born to mothers receiving zidovudine monotherapy during pregnancy. The Italian register for HIV Infection in Children.

OBJECTIVE: To investigate the outcome in children perinatally infected with HIV-1 whose mothers received zidovudine (ZDV) monotherapy in pregnancy. DESIGN: Observational retrospective study of a prospectively recruited cohort. SETTING: Italian Register for HIV Infection in Children. PATIENTS: A group of 216 children perinatally infected with HIV-1, born in 1992-1997 and derived prospectively from birth: 38 children had mothers receiving ZDV monotherapy and for 178 children the mothers received no antiretroviral treatment during pregnancy. MAIN OUTCOME MEASURES: The estimated probability of developing severe disease or severe immune suppression, survival probability [95% confidence interval (CI)] within 3 years, and the hazard ratio (95% CI), adjusted for year of birth, maternal clinical condition at delivery, birthweight and treatments (Pneumocystis carinii pneumonia chemoprophylaxis and/or antiretroviral therapy before the onset of severe disease, severe immune suppression or death) were compared. RESULTS: Comparison of HIV-1-infected children whose mothers were treated with ZDV with children whose mothers were not treated showed that the former group had a higher probability of developing severe disease [57.3% (95% CI 40.9-74.3) versus 37.2% (95% CI 30.0-45.4); log-rank test 7.83, P = 0.005; adjusted hazard ratio 1.8 (95% CI 1.1-3.1)] or severe immune suppression [53.9% (95% CI 36.3-73.5) versus 37.5% (95% CI 30.0-46.2); log-rank test 5.58, P = 0.018; adjusted hazard ratio 2.4, (95% CI: 1.3-4.3)] and a lower survival [72.2% (95% CI 50.4-85.7) versus 81.0% (95% CI 73.7-86.5); log-rank test 4.23, P = 0.039; adjusted hazard ratio of death 1.9 (95% CI 1.1-3.6)]. CONCLUSIONS: This epidemiological observation could stimulate virologic studies to elucidate whether this rapid progression depends on in utero infection or transmission of resistant virus. Findings may suggest a need to hasten HIV-1 diagnosis in infants of ZDV-treated mothers and undertake an aggressive antiretroviral therapy in those found to be infecte