The value of 3.0Tesla diffusion-weighted MRI for pelvic nodal staging in patients with early stage cervical cancer

Contains fulltext : 109962.pdf (publisher's version ) (Open Access)OBJECTIVE: The purpose of this study is to investigate the diagnostic accuracy of 3.0Tesla (3T) diffusion-weighted magnetic resonance imaging (MRI) in addition to conventional MRI for the detection of lymphadenopathy in patients with early stage cervical cancer compared to histopathological evaluation of the systematically removed pelvic lymph nodes as reference standard. METHODS: 68 federation internationale de gynecologie obstetrique (FIGO) stage Ia2 to IIb cervical cancer patients were included. Sensitivity and specificity rates for two experienced observers were computed for the detection of lymphatic metastasis. Reproducibility of conventional MRI was tested by kappa statistics. The variables included in the analysis were: size of the long axis, short axis, ratio short to long axis and apparent diffusion coefficient (ADC). RESULTS: Nine patients had 15 positive pelvic nodes at histopathological examination. The sensitivity and specificity of lymphatic metastasis detection by predefined conventional MRI characteristics was 33% (95% Confidence Interval (CI) 3-64) and 83% (95% CI 74-93) on patient level, and 33% (95% CI 7-60) and 97% (95% CI 95-99) on regional level respectively for observer 1. For observer 2 the sensitivity was 33% (95% CI 3-64) and the specificity 93% (95% CI 87-100) on patient level, and 25% (95% CI 1-50) and 98% (95% CI 97-100) on regional level, respectively. The kappa-value for reproducibility of metastasis detection on regional level was 0.50. The short axis diameter showed the highest diagnostic accuracy (area under the curve (AUC)=0.81 95% CI 0.70-0.91); ADC did not improve diagnostic accuracy (AUC=0.83 95% CI 0.73-0.93). CONCLUSIONS: Diffusion-weighted MRI did not result in additional diagnostic value compared to conventional MRI

Efficient Cryptosystems From 2^k-th Power Residue Symbols

Goldwasser and Micali (1984) highlighted the importance of randomizing the plaintext for public-key encryption and introduced the notion of semantic security. They also realized a cryptosystem meeting this security notion under the standard complexity assumption of deciding quadratic residuosity modulo a composite number. The Goldwasser-Micali cryptosystem is simple and elegant but is quite wasteful in bandwidth when encrypting large messages. A number of works followed to address this issue and proposed various modifications. This paper revisits the original Goldwasser-Micali cryptosystem using 2 k-th power residue symbols. The so-obtained cryptosystems appear as a very natural generalization for k ≥ 2 (the case k = 1 corresponds exactly to the Goldwasser-Micali cryptosystem). Advantageously, they are efficient in both bandwidth and speed; in particular, they allow for fast decryption. Further, the cryptosystems described in this paper inherit the useful features of the original cryptosystem (like its homomorphic property) and are shown to be secure under a similar complexity assumption. As a prominent application, this paper describes an efficient lossy trapdoor function based thereon