Genetic algorithm-based optimization of pulse sequences.

PURPOSE: The performance of pulse sequences in vivo can be limited by fast relaxation rates, magnetic field inhomogeneity, and nonuniform spin excitation. We describe here a method for pulse sequence optimization that uses a stochastic numerical solver that in principle is capable of finding a global optimum. The method provides a simple framework for incorporating any constraint and implementing arbitrarily complex cost functions. Efficient methods for simulating spin dynamics and incorporating frequency selectivity are also described. METHODS: Optimized pulse sequences for polarization transfer between protons and X-nuclei and excitation pulses that eliminate J-coupling modulation were evaluated experimentally using a surface coil on phantoms, and also the detection of hyperpolarized [2-13 C]lactate in vivo in the case of J-coupling modulation-free excitation. RESULTS: The optimized polarization transfer pulses improved the SNR by ~50% with a more than twofold reduction in the B1 field, and J-coupling modulation-free excitation was achieved with a more than threefold reduction in pulse length. CONCLUSION: This process could be used to optimize any pulse when there is a need to improve the uniformity and frequency selectivity of excitation as well as to design new pulses to steer the spin system to any desired achievable state.

Managing COVID-19 in a Novel, Rapidly Deployable Community Isolation Quarantine Facility.

Singapore is one of the most densely populated small island-states in the world. During the coronavirus disease 2019 (COVID-19) pandemic, Singapore implemented large-scale institutional isolation units called Community Care Facilities (CCFs) to combat the outbreak in the community by housing low-risk COVID-19 patients from April to August 2020. The CCFs were created rapidly by converting existing public spaces and used a protocolized system, augmented by telemedicine to enable a low health care worker-patient ratio (98 health care workers for 3200 beds), to operate these unique facilities. In the first month, a total of 3758 patients were admitted to 4 halls, 4929 in-house medical consults occurred, 136 patients were transferred to a hospital, 1 patient died 2 weeks after discharge, and no health care workers became infected. This article shares the authors' experience in operating these massive-scale isolation facilities while prioritizing safety for all and ensuring holistic patient care in the face of a public health crisis and lean health care resources.

Serum progesterone distribution in normal pregnancies compared to pregnancies complicated by threatened miscarriage from 5 to 13 weeks gestation: a prospective cohort study.

BACKGROUND: Progesterone is a critical hormone in early pregnancy. A low level of serum progesterone is associated with threatened miscarriage. We aim to establish the distribution of maternal serum progesterone in normal pregnancies compared to pregnancies complicated by threatened miscarriage from 5 to 13 weeks gestation. METHODS: This is a single centre, prospective cohort study of 929 patients. Women from the Normal Pregnancy [NP] cohort were recruited from antenatal clinics, and those in the Threatened Miscarriage [TM] cohort were recruited from emergency walk-in clinics. Women with multiple gestations, missed, incomplete or inevitable miscarriage were excluded from the study. Quantile regression was used to characterize serum progesterone levels in the NP and TM cohorts by estimating the 10th, 50th and 90th percentiles from 5 to 13 weeks gestation. Pregnancy outcome was determined at 16 weeks of gestation. Subgroup analysis within the TM group compared progesterone levels of women who subsequently miscarried with those who had ongoing pregnancies at 16 weeks of gestation. RESULTS: Median serum progesterone concentration demonstrated a linearly increasing trend from 57.5 nmol/L to 80.8 nmol/L from 5 to 13 weeks gestation in the NP cohort. In the TM cohort, median serum progesterone concentration increased from 41.7 nmol/L to 78.1 nmol/L. However, median progesterone levels were uniformly lower in the TM cohort by approximately 10 nmol/L at every gestation week. In the subgroup analysis, median serum progesterone concentration in women with ongoing pregnancy at 16 weeks gestation demonstrated a linearly increasing trend from 5 to 13 weeks gestation. There was a marginal and non-significant increase in serum progesterone from 19.0 to 30.3 nmol/L from 5 to 13 weeks gestation in women who eventually had a spontaneous miscarriage. CONCLUSIONS: Serum progesterone concentration increased linearly with gestational age from 5 to 13 weeks in women with normal pregnancies. Women with spontaneous miscarriage showed a marginal and non-significant increase in serum progesterone. This study highlights the pivotal role of progesterone in supporting an early pregnancy, with lower serum progesterone associated with threatened miscarriage and a subsequent complete miscarriage at 16 weeks gestation.

Diverticular Disease of the Appendix Is Associated with Complicated Appendicitis.

INTRODUCTION: Diverticular disease of the vermiform appendix (DDA) has an incidence of 0.004 to 2.1% in appendicectomy specimens. DDA is variably associated with perforation and malignancy. We report a single-center experience of DDA. The primary aim is to validate the association of DDA with complicated appendicitis or malignancy, and the secondary aim is to validate systemic inflammatory response syndrome (SIRS) criteria and quick Sepsis-related Organ Failure Assessment (qSOFA) scores. METHODS: The histopathology reports of 2,305 appendicectomy specimens from January 2011 to December 2015 were reviewed. Acute appendicitis was found in 2,164 (93.9%) specimens. Histology of the remaining 141 (6.1%) patients revealed: normal appendix (n = 110), DDA (n = 22), endometriosis of appendix (n = 6), and an absent appendix (n = 3). Patient demographics, clinical profile, operative data, and perioperative outcomes of DDA patients are studied. Modified Alvarado score, Andersson score, SIRS criteria, and qSOFA scores were retrospectively calculated. RESULTS: The incidence of DDA was 0.95%. Ten patients (45.5%) had diverticulitis. The mean age of DDA patients was 39.5 years (range 23-87), with male preponderance (n = 12, 54.5%). The median Modified Alvarado score was 8 (range 4-9), and the median Andersson score was 5 (range 2-8). Fourteen patients (63.6%) had SIRS, and none had a high qSOFA score. Eight patients (36.4%) had complicated appendicitis (perforation [n = 2] or abscess [n = 6]). Eleven (50%) patients underwent laparoscopic appendicectomy. There were three 30-day readmissions and no mortality. CONCLUSION: DDA is a distinct clinical pathology associated with complicated appendicitis.

INTRODUÇÃO: A doença diverticular do apêndice vermiforme (DDA) tem uma incidência de 0,004 a 2,1% em peças de apendicectomia. DDA está de forma variável associada a perfuração e malignidade. Reportamos uma experiência unicêntrica de DDA. O objectivo primário é validar a associação de DDA com apendicite complicada ou malignidade, e o objectivo secundário é validar os critérios de Systemic Inflammatory Response Syndrome (SIRS) e o score de quick Sepsis-related Organ Failure Assessment (qSOFA). MÉTODOS: Os relatórios histopatológicos de 2,305 peças de apendicectomia de Janeiro 2011 a Dezembro de 2015 foram revistos. Apendicite aguda foi verificada em 2,164 (93,9%) peças. A histologia das restantes 141 (6,1%) revelou: apêndice normal (n = 110), DDA (n = 22), endometriose do apêndice (n = 6) e apêndice ausente (n = 3). As características demográficas dos doentes, perfil clínico, dados cirúrgicos e perioperatórios dos doentes com DDA foram avaliados. Modified Alvarado score, Andersson score, SIRS criteria, e o qSOFA scores foram calculados retrospectivamente. RESULTADOS: A incidência de DDA foi de 0,95%. Dez doentes (45,5%) tinham diverticulite. A idade média dos doentes com DDA foi de 39,5 anos (âmbito 23­87) com predominância masculina (n = 12, 54,5%). A mediana do Modified Alvarado score foi de 8 (âmbito 4­9), e a mediana do Andersson score foi de 5 (âmbito 2­8). Quatorze doentes (63,6%) tinham SIRS e nenhum tinha um qSOFA score alto. Oito doentes (36,4%) tinham apendicite complicada (perfuração n = 2; abcesso n = 6). Onze (50%) doentes foram submetidos a apendicectomia laparoscópica. Verificaram-se 3 readmissões aos 30 dias e nenhuma morte. CONCLUSÃO: DDA é uma entidade clínica e patológica distinta e está associada a apendicite complicada.

Computerized tomography scan in acute appendicitis with eventual negative appendectomy.

BACKGROUND AND AIM: Acute appendicitis (AA) is traditionally considered a clinical diagnosis and negative appendectomy (NA) rates vary across health-care systems. Computed tomography (CT) scans have been shown to aid in the reduction of NA rates. Our study aimed to determine the pre-operative imaging characteristics in patients undergoing appendectomy with eventual normal histology. MATERIALS AND METHODS: An audit of all patients with a discharge diagnosis of AA was conducted from January 2011 to December 2015. Histology reports of all patients who underwent appendectomies were reviewed, and medical records of patients with NA were included in the study. To study the impact of CT scan reporting in NA patients, CT scan images of patients with NA were reviewed retrospectively by two blinded radiologists. RESULTS: A total of 2603 patients underwent appendectomy for suspected AA, and NA rate was 3.34% (n=87). The mean age of patients with NA was 30.3 (14.8-69.8) years with no gender difference (51.7% male). Sixty-six (75.9%) patients had laparoscopic appendectomy with 3.5% open conversion rate. CT scans were done in 47 patients. Pre-operative CT scan report was more likely to report dilated appendix (n=26 [55.3%] vs. n=7 [14.9%], P=0.0001). Post-operative blinded radiology review was more like to report other pathology (n=27 [57.4%] vs. n=2 [4.3%], P=0.0001) and normal appendix (n=26 [55.3%] vs. n=5 (10.6%), P=0.0001). CONCLUSION: The NA rate is low. There needs to be standardized reporting for imaging features of prominent/dilated appendix. RELEVANCE FOR PATIENTS: Appendectomy must be avoided in patients with a normal CT scan and when another pathological diagnosis is established. Liberal imaging policy assists to reduce NA rates. Imaging features of prominent or dilated appendix can be subjective and international collaboration is needed to define thresholds for imaging diagnosis of AA.