RADIOPEDIA ARTICLES

موضوع: RADIOPEDIA ARTICLES الخميس أبريل 18, 2019 8:59 pm

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https://radiopaedia.org/articles/early-pregnancy?lang=gb



MD radiology sudan medical specialization board SMSB dr Tarteel kamal sayed RADIOPEDIA [rtl]https://radiopaedia.org[/rtl] RADIOPEDIA ARTICLES https://radiopaedia.org/articles/11-13-week-antenatal-scan?lang=gb 11-13 w11-13 week antenatal scan is considered a routine investigation advised for the fetal well being as well as (for early screening in pregnancy (see antenatal screening It includes multiple components and is highly dependant on the operator. Traditionally three factors are used to calculate the risk of trisomies: (crown rump length (must be 45 to 84 mm, gestation age 11 weeks 3 days to 13 weeks 6 days* nuchal translucency* fetal heart rate* Additional markers increase the detection rate and reduce the false positive rates: nasal bone ductus venosus flow tricuspid flow Combining these factors with blood tests (i.e. dual marker) has been reported to achieve nearly 95% detection rate for trisomies. Apart from the screening protocol, early detection of major anomalies may be possible and the checklist must include the following conditions: acrania encephalocele alobar holoprosencephaly iniencephaly body stalk deformity gastroschisis omphalocele limb reduction megacystis Quiz questions Which of the following statement is false regarding 11-13 weeks antenatal scan? fetal urinary bladder length more than 7 mm increases the risk of trisomy 13/18 none presence of atrioventricular septal defect increases the risk of trisomy 21 presence of diaphragmatic hernia increases the risk of trisomy 18 presence of holoprosencephaly increases the risk of trisomy 13 with CRL more than 55 mm, if omphalocele is present, it increases the risk of trisomy 13 to 1:10 and trisomy 18 to 1:4 regardless of any other finding. ANS : none Explanation All of the statements are true regarding 11-13 weeks antenatal scan with CRL <55 mm, omphalocele containing only bowel is not taken into risk calculation for trisomies as this may be physiological herniation, however, if there is liver in the herniated contents, it will increase the risk even with CRL <55 mm fetal urinary bladder length between 7-15 mm increases the risk of trisomy 13/18 more as compared to the length greater than 15 mm a diaphragmatic hernia increases the risk of trisomy 18 to 1:4 atrioventricular septal defect increases the risk of trisomy 21 to 1:2 holoprosencephaly increases the risk of trisomy 13 to 1:2 next Q

موضوع: رد: RADIOPEDIA ARTICLES الخميس أبريل 18, 2019 9:16 pm



Early pregnancy Early pregnancy roughly spans the first ten weeks of the first trimester. https://radiopaedia.org/articles/early-pregnancy?lang=gb Radiographic features Antenatal ultrasound zero - 4.3 weeks: no ultrasound findings w4.3 - 5 weeks possible small gestational sac (possible double decidual sac sign (DDSS (possible intradecidual sac sign (IDSS 5.1-5.5 weeks: gestational sac should be visible by this time 5.5-6.0 weeks yolk sac should be visible by this time gestational sac should be ~6 mm in diameter double bleb sign more than 6 wks (fetal pole may be identifiable on endovaginal ultrasound (1-2 mm fetal heart rate (FHR) should be ~100-115 bpm gestational sac should be ~10 mm in diameter 6.5 weeks crown rump length (CRL) should be ~5 mm 7-8 weeks CRL is between 11-16 mm cephalad and caudal poles can be identified 8-9 weeks CRL is between 17-23 mm limb buds appear head can be seen as separate from the body 9-10 weeks CRL is between 23-32 mm fetal heart rate 170-180 bpm fetal movement can be seen a round hypoechoic structure in the fetal brain represents a developing embryonic/fetal rhombencephalon nuchal translucency may begin to be seen Transvaginal/endovaginal (TV/EV) scanning intradecidual sac sign (IDSS): early sign on a TV scan when the MSD measures 25 mm, an embryo must be visible when the CRL measures >7 mm, an embryo must show cardiac activity an embryo should be seen <=14 days after a scan with a gestational sac without a yolk sac an embryo should be seen <=11 days after a scan with a gestational sac and a yolk sac Transabdominal (TA) scanning when the MSD measures 20 mm a yolk sac should be visible when the MSD measures 25 mm, an embryo must be visible CT/MRI Occasionally, early pregnancy is unintentionally imaged by CT or sometimes MRI is done for some concurrent pathology, and its important to know the imaging findings 3. fluid-filled cystic structure in endometrial cavity (well identified on MRI, and may be visible on CT especially on delayed post-contrast images) developing placenta seen as curvilinear enhancing structure fetal pole may be seen in delayed first trimester imaging corpus luteal cyst may be visible in one of the ovaries unilocular <3 cm cyst with irregular crenated and enhancing walls Differential diagnosis to be considered with a positive urinary pregnancy test includes ectopic pregnancy missed abortion gestational trophoblastic disease If urinary pregnancy test is negative similar findings may suggest submucosal fibroid or retained products of conception. Practical points The earlier in pregnancy a scan is performed, the more accurate the age assignment from crown rump length. The initial age assignment should not be revised on subsequent scans 5. (Overall, the accuracy of sonographic dating in the first trimester is ~5 days (95% confidence range

موضوع: رد: RADIOPEDIA ARTICLES الخميس أبريل 18, 2019 9:18 pm



First trimester of pregnancy first trimester ultrasound findings in early pregnancy gestational sac (mean sac diameter (MSD yolk sac fetal pole (crown rump length (CRL confirming intrauterine gestation double decidual sac sign intradecidual sign double bleb sign (pregnancy of unknown location (PUL first trimester vaginal bleeding ectopic pregnancy pseudogestational sac decidual cast tubal ectopic ampullary isthmal fimbrial atypical ectopic pregnancies interstitial ectopic eccentric gestational sac interstitial line sign ovarian ectopic cervical ectopic scar ectopic abdominal ectopic live ectopic pregnancy heterotopic pregnancy tubal rupture failed early pregnancy (pregnancy of uncertain viability (PUV miscarriage threatened miscarriage irregular gestational sac missed miscarriage inevitable miscarriage incomplete miscarriage complete miscarriage anembryonic pregnancy anembryonic pregnancy in the exam yolk sac abnormalities irregular yolk sac calcified yolk sac echogenic yolk sac small yolk sac large yolk sac gestational trophoblastic disease subchorionic haemorrhage demise of a twin implantation bleeding aneuploidy testing antenatal screening 11-13 weeks antenatal scan nuchal translucency

موضوع: رد: RADIOPEDIA ARTICLES الخميس أبريل 18, 2019 9:19 pm



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موضوع: رد: RADIOPEDIA ARTICLES الخميس أبريل 18, 2019 9:20 pm



Eleven ribs or less is associated with a number of congenital abnormalities and skeletal dysplasias, including: Down syndrome, Trisomy 21 campomelic dysplasia kyphomelic dysplasias (asphyxiating thoracic dysplasia (Jeune syndrome short rib polydactyly syndromes trisomy 18 chromosome 1q21.1 deletion syndrome atelosteogenesis spondylocostal dysostosis spondylometaphyseal dysplasia, Sedaghatain type Ritscher-Schinzel syndrome ******* 1.5Tesla vs 3.0 T Comparing 1.5 T vs 3.0 T (1.5 tesla vs 3.0 tesla) MRI systems identifies a number of differences; a 3 T system has (increased signal-to-noise ratio (SNR increased spatial resolution increased temporal resolution (increased specific absorption rate (SAR increased acoustic noise Signal-to-noise ratio Theoretically, signal is proportional to the square of the static field strength (B0) whereas noise increases linearly. This implies that, in a perfect system, the signal-to-noise ratio (SNR) of a 3 T system would be twice as good as at 1.5 T. In reality, due to an increase in susceptibility effects in most tissues, the actual improvement is only in the 30-60% range (instead of 100%). With this increased SNR, the spatial resolution and/or acquisition time can be improved, depending on which is more important for the particular case. Specific absorption rate Specific absorption rate (SAR) is defined as the amount of radiofrequency energy (joules) deposited in tissues (kg). The limit set by the FDA is an amount which results in an increase of 1-degree centigrade in any tissue 2. SAR is proportional to the static field (B0) squared, meaning that a 3 T system deposits 4 times as much energy within tissue as a 1.5 T system. Additionally, SAR is proportional to pulse duration and length pulse number slice number flip angle The dependence of SAR on flip angle results in a relatively large amount of energy deposition for standard spin echo sequences since they use 90-degree flip angles. As a result, there is increased use of gradient echo sequences, which use smaller flip angles. Unfortunately, these latter sequences image T2* and not T2, and are therefore more susceptible to local field artefacts. These problems have largely been overcome with modern units. Acoustic noise Rapid gradient switching leads to an increase in the intensity of the acoustic noise, which requires better insulation of both the unit itself and the containing room. Quiz questions Changing from a 1.5 Tesla to a 3 Tesla MRI system will: increase spatial resolution, increase signal-to-noise ratio and decrease temporal resolution increase spatial resolution, decrease signal-to-noise ratio and decrease temporal resoution increase spatial resolution, increase signal-to-noise ratio and increase temporal resolution decrease spatial resolution, increase signal-to-noise ratio and decrease temporal resolution decrease spatial resolution, decrease signal-to-noise ratio and decrease temporal resoution [rtl]https://radiopaedia.org/articles/15-t-vs-30-t?lang=gb[/rtl] Explanation see [rtl]https://radiopaedia.org/articles/15t-vs-3t[/rtl]

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