•Simulation of the Impact of SARS-CoV-2 variants and vaccines on the spread of COVID.•New θ-SIR type model ready (and freely available) to be used with real data.•Application to the case of Italy. A ...new variant may cause a new disease wave.•Current rates of vaccination might not be enough to avoid a new disease wave.•Effective reproduction number <1 is not enough for having COVID-19 under control.
The continuous mutation of SARS-CoV-2 opens the possibility of the appearance of new variants of the virus with important differences in its spreading characteristics, mortality rates, etc. On 14 December 2020, the United Kingdom reported a potentially more contagious coronavirus variant, present in that country, which is referred to as VOC 202012/01. On 18 December 2020, the South African government also announced the emergence of a new variant in a scenario similar to that of the UK, which is referred to as variant 501.V2.
Another important milestone regarding this pandemic was the beginning, in December 2020, of vaccination campaigns in several countries. There are several vaccines, with different characteristics, developed by various laboratories and research centers.
A natural question arises: what could be the impact of these variants and vaccines on the spread of COVID-19?
Many models have been proposed to simulate the spread of COVID-19 but, to the best of our knowledge, none of them incorporates the effects of potential SARS-CoV-2 variants together with the vaccines in the spread of COVID-19. We develop here a θ−ij-SVEIHQRD mathematical model able to simulate the possible impact of this type of variants and of the vaccines, together with the main mechanisms influencing the disease spread. The model may be of interest for policy makers, as a tool to evaluate different possible future scenarios.
We apply the model to the particular case of Italy (as an example of study case), showing different outcomes. We observe that the vaccines may reduce the infections, but they might not be enough for avoiding a new wave, with the current expected vaccination rates in that country, if the control measures are relaxed. Furthermore, a more contagious variant could increase significantly the cases, becoming the most common way of infection. We show how, even with the pandemic cases slowing down (with an effective reproduction number less than 1) and the disease seeming to be under control, the effective reproduction number of just the new variant may be greater than 1 and, eventually, the number of infections would increase towards a new disease wave. Therefore, a rigorous follow-up of the evolution of the number of infections with any potentially more dangerous new variant is of paramount importance at any stage of the pandemic.
Objective
The aim of the Female Pelvic Imaging Working Group of the European Society of Urogenital Radiology (ESUR) was to develop imaging guidelines for MR work-up in patients with known or ...suspected uterine leiomyomas.
Methods
Guidelines for imaging uterine leiomyomas were defined based on a survey distributed to all members of the working group, an expert consensus meeting at European Congress of Radiology (ECR) 2017 and a critical review of the literature.
Results
The 25 returned questionnaires as well as the expert consensus meeting have shown reasonable homogeneity of practice among institutions. Expert consensus and literature review lead to an optimized MRI protocol to image uterine leiomyomas. Recommendations include indications for imaging, patient preparation, MR protocols and reporting criteria. The incremental value of functional imaging (DWI, DCE) is highlighted and the role of MR angiography discussed.
Conclusions
MRI offers an outstanding and reproducible map of the size, site and distribution of leiomyomas. A standardised imaging protocol and method of reporting ensures that the salient features are recognised. These imaging guidelines are based on the current practice among expert radiologists in the field of female pelvic imaging and also incorporate essentials of the current published MR literature of uterine leiomyomas.
Key Points
•
MRI allows comprehensive mapping of size and distribution of leiomyomas.
•
Basic MRI comprise T2W and T1W sequences centered to the uterus.
•
Standardized reporting ensures pivotal information on leiomyomas, the uterus and differential diagnosis.
•
MRI aids in differentiation of leiomyomas from other benign and malignant entities, including leiomyosarcoma.
Objective
Non-mass enhancement (NME) in breast MRI is the most common feature of ductal carcinoma in situ (DCIS). We sought to evaluate the interobserver variability and positive predictive value ...(PPV) for malignancy of NME descriptors using the fifth edition BI-RADS lexicon focusing on the newly introduced “clustered ring enhancement” pattern.
Materials and methods
Breast MRIs of 129 patients who had undergone MRI-guided vacuum-assisted biopsy (VAB) in our institution were reviewed. Studies assessed as NME were classified according to the fifth edition BI-RADS lexicon by two breast radiologists. Consensus was reached by involving a third radiologist. Interobserver variability and PPV for malignancy were assessed.
Results
Seventy-two of 129 studies were assessed as NME. The disagreement rate in the first assessment step (mass vs. NME) was low at 9.3% (
ĸ
= 0.81, 95% confidence interval CI 0.71–0.91). The disagreement rate for distribution patterns was 23.6% (
ĸ
= 0.67, 95% CI 0.54–0.80) and 22.2% (
ĸ
= 0.69, 95% CI 0.56–0.81) for internal enhancement patterns. Clustered ring enhancement (PPV 53.85,
p =
0.038) and segmental distribution (PPV 62.5%,
p =
0.028) had the highest malignancy rates among internal enhancement and distribution patterns with a significant result; the combination of clustered ring enhancement and segmental distribution raised the malignancy rate by approximately 4% (PPV 66.67%,
p
= 0.049).
Conclusion
There was a high agreement rate among readers when differentiating NME from mass lesions. The agreement rate was lower when assessing the distribution and internal enhancement pattern descriptors, but still substantial. The descriptors clustered ring enhancement and segmental distribution were significant predictors of malignancy.
Key Points
• Non-mass enhancement is a common morphological feature of non-invasive breast cancer (DCIS) in MRI. Differentiation between potentially malignant and benign changes may be very challenging.
• Since clustered ring enhancement and segmental distribution are both significant predictors of malignancy, the awareness of this important finding, combined with high-quality image interpretation skills, may improve the tumor detection rate.
• The combination of clustered ring enhancement and segmental distribution increases the positive predictive value for malignancy, which may be relevant for clinical practice
.
Since the start of the COVID-19 pandemic in China many models have appeared in the literature, trying to simulate its dynamics. Focusing on modeling the biological and sociological mechanisms which ...influence the disease spread, the basic reference example is the SIR model. However, it is too simple to be able to model those mechanisms (including the three main types of control measures: social distancing, contact tracing and health system measures) to fit real data and to simulate possible future scenarios. A question, then, arises: how much and how do we need to complexify a SIR model? We develop a θ-SEIHQRD model, which may be the simplest one satisfying the mentioned requirements for arbitrary territories and can be simplified in particular cases. We show its very good performance in the Italian case and study different future scenarios.
•Mathematical model for coronavirus disease (COVID-19).•New θ-SEIHQRD model taking into account quarantine and undetected infections.•Validation of the model with the reported data for Italy.•New formula for the effective reproduction number.•Different scenarios to show the impact of undetected cases and control measures.
Background
High‐intensity focused ultrasound (HIFU) emerged as a novel approach for the treatment of localized prostate cancer (PCa). However, prospective studies on HIFU‐related outcomes and ...predictors of treatment failure (TF) remain scarce.
Materials and Methods
We conducted a multinational prospective cohort study among patients undergoing HIFU therapy for localized, low‐ to intermediate‐risk PCa. Follow‐up data on serial prostate specific antigen (PSA), multi‐parametric magnetic resonance imaging (mpMRI), targeted/systematic biopsies, adverse events and functional outcomes were collected. The primary endpoint was TF, defined as histologically confirmed PCa requiring whole‐gland salvage treatment. Uni‐ and multi‐variable adjusted hazard ratios (HRs) were calculated using Cox proportional hazard regression models.
Results
At baseline, mean (standard deviation) age was 64.14 (7.19) years, with the majority of patients showing T‐stage 1 (73.9%) and International Society of Urological Pathology grading system Grade 2 (58.8%). PSA nadir (median, 1.70 ng/mL) was reached after 6 months. Of all patients recruited, 16% had clinically significant PCa, as confirmed by biopsy, of which 13.4% had TF. Notably, T‐stage and number of positive cores at initial biopsy were independent predictors of TF during follow‐up (HR 95% CI 1.27 1.02–1.59 and 5.02 1.80–14.03, respectively). Adverse events were minimal (17% and 8% early and late adverse events, respectively), with stable or improved functional outcomes in the majority of patients.
Conclusions
This interim analysis of a multinational study on HIFU therapy for the management of low‐to‐intermediate‐risk PCa reveals good functional outcomes, minimal adverse events and low incidence of TF over the short‐term. Data on long‐term outcomes, specifically as it relates to oncological outcomes, are awaited eagerly.
This study examines outcomes and predictors of treatment failure (TF) following high‐intensity focused ultrasound (HIFU) therapy for localized prostate cancer (PCa). A multinational prospective cohort study was conducted, analysing serial prostate specific antigen (PSA), MRI, biopsies, adverse events and functional outcomes. Results show low incidence of TF, with initial T‐stage and positive biopsy cores predicting TF. Minimal adverse events and positive functional outcomes were observed. The findings highlight HIFU as a promising treatment for low‐to‐intermediate‐risk PCa, though long‐term data are needed to assess oncological outcomes.
Purpose To evaluate whether gadolinium penetrates human cerebrospinal fluid (CSF) after MR imaging (MRI) with a gadolinium-based contrast agent (GBCA). Materials and Methods For this retrospective ...study, the authors analyzed 60 CSF samples from 57 patients (median age, 50 years; range, 3-92 years) who underwent one contrast material-enhanced MRI examination with gadoterate meglumine within 60 days of CSF extraction between January and December 2016. CSF samples from patients who underwent MRI without contrast material administration (n = 22) or those who underwent contrast-enhanced MRI at least 1 year before extraction (n = 2) were analyzed and used as control samples. CSF measurements were performed with inductively coupled plasma mass spectrometry by monitoring the gadolinium 158 isotope. Statistical analyses were performed by using a preliminary Kruskal-Wallis test. Results Higher CSF gadolinium concentrations were detected within the first 8 hours after GBCA administration (mean concentration, 1152 ng/mL ± 734.6). Concentrations were lower between 8 and 48 hours (872 ng/mL ± 586). After 48 hours, gadolinium was almost completely cleared from CSF (121 ng/mL ± 296.3). All but two samples from the 24 control patients (median age, 60.5 years; range, 19-79 years) were negative for the presence of gadolinium. Those samples were from patients who had undergone GBCA-enhanced MRI examination more than a year before CSF extraction (0.1 and 0.2 ng/mL after 1 and 3 years, respectively). The concentrations in patients with chronic renal insufficiency (n = 3), cerebral toxoplasmosis (n = 1), and liver cirrhosis (n = 1) were higher than the mean concentrations. Conclusion Gadoterate meglumine can be detected in human CSF after intravenous administration.
Abstract Functional imaging by means of dynamic multiphase contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion weighted magnetic resonance imaging (DW-MRI) is now part of the ...standard imaging protocols for evaluation of the female pelvis. DCE-MRI and DW-MRI are important MR imaging techniques which enable the radiologist to move from morphological to functional assessment of diseases of the female pelvis. This is mainly due to the limitations of morphologic imaging, particularly in lesion characterization, accurate lymph node staging, assessment of tumour response and inability to differentiate post-treatment changes from tumour recurrence. DCE-MRI improves the accuracy of T2WI in staging of endometrial cancer. It also helps differentiate tumour recurrence from radiation fibrosis in patients with cervical cancer. DCE-MRI improves characterization of cystic adnexal lesions and detection of small peritoneal implants in patients with ovarian cancer. DW-MRI is valuable in preoperative staging of patients with endometrial and cervical cancer, especially in detection of extra-uterine disease. It does increase reader's confidence for detection of recurrent disease in gynaecological malignancies and improves detection of small peritoneal implants in patients with ovarian cancer. In this review article we give an overview of both DCE-MRI and DW-MRI techniques, concentrating on their main clinical application in the female pelvis, and present a practical approach of the added value of these techniques according to the main pathological conditions, highlighting the pearls and pitfalls of each technique.
OBJECTIVES:Phase-contrast and scattering-based x-ray imaging are known to provide additional and complementary information to conventional, absorption-based methods, and therefore have the potential ...to play a crucial role in medical diagnostics. We report on the first mammographic investigation of 5 native, that is, freshly dissected, breasts carried out with a grating interferometer and a conventional x-ray tube source. Four patients in this study had histopathologically proven invasive breast cancer. One male patient, without the presence of any malignant formations within the resected breast, was included as a control specimen.
MATERIALS AND METHODS:We used a Talbot-Lau grating setup installed on a conventional, low-brilliance x-ray source; the interferometer operated at the fifth Talbot distance, at a tube voltage of 40 kVp with mean energy of 28 keV, and at a current of 25 mA. The device simultaneously recorded absorption, differential phase and small-angle scattering signals from the native breast tissue. These quantities were then combined into novel color- and high-frequency-enhanced radiographic images. Presurgical images (conventional mammography, ultrasonography, and magnetic resonance imaging) supported the findings and clinical relevance was verified.
RESULTS:Our approach yields complementary and otherwise inaccessible information on the electron density distribution and the small-angle scattering power of the sample at the microscopic scale. This information can be used to potentially answer clinically relevant, yet unresolved questions such as unequivocally discerning between malignant and premalignant changes and postoperative scars and distinguishing cancer-invaded regions within healthy tissue.
CONCLUSIONS:We present the first ex vivo images of fresh, native breast tissue obtained from mastectomy specimens using grating interferometry. This technique yields improved diagnostic capabilities when compared with conventional mammography, especially when discerning the type of malignant conversions and their breadth within normal breast tissue. These promising results advance us toward the ultimate goal, using grating interferometry in vivo on humans in a clinical setting.
The proposed Mitchell Institute Neutrino Experiment at Reactor (MINER) experiment at the Nuclear Science Center at Texas A&M University will search for coherent elastic neutrino-nucleus scattering ...within close proximity (about 2m) of a 1MW TRIGA nuclear reactor core using low threshold, cryogenic germanium and silicon detectors. Given the Standard Model cross section of the scattering process and the proposed experimental proximity to the reactor, as many as 5–20events/kg/day are expected. We discuss the status of preliminary measurements to characterize the main backgrounds for the proposed experiment. Both in situ measurements at the experimental site and simulations using the MCNP and GEANT4 codes are described. A strategy for monitoring backgrounds during data taking is briefly discussed.
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