2.depicts biliary ducts upstream and down stream from the lesion and extra ductile pathology
3.high water content of bile creates major problem in imaging
4.useful in pre-op and post - op evaluation of biliary drainage
Ans— 3
High water content in bile is exploited for imaging in MRCP.
MR cholangiopancreatography (MRCP) is a noninvasive method that is widely used in the evaluation of pancreatobiliary disorders.
MRCP depicts biliary ducts upstream and downstream from an eventual lesion, as well as extraductal diseases when combined with additional T1- and T2-weighted imaging or even the use of contrast media.
The high water content in bile composition and its relative stasis in the bile ducts are unique properties that are exploited to aid visualization with nearly all MRCP sequences
MRCP is useful in pre- and postoperative evaluation of biliary drainage, since it allows excellent visualization of the biliary ducts and possible ana- tomic variations.
MRCP also has its disadvantages. Although it is less operator de- pendent than US, it is more expensive and requires a longer period of time to perform imaging.
In comparison with ERCP, MRCP cannot be used during interventions such as biopsy since it is a noninvasive method. It also has poorer spatial resolution when compared with en- doscopic or even percutaneous cholangiography. Patients play an im- portant role in the MRCP examination since they are responsible for cooperation by holding their breath or staying still during the study
All are true regarding role of MRI inhepatic steatosis except
1.liver appear bright in opposed phase of chemical shift imaging (CSI)
2.MRI -PDFF has better accuracy than double echo CSI for fat quantification
3.MRI - PDFF can assess the fat content of entire liver in short breath hold
4.MRI- PDFF has high accuracy in assessing hepatic steatosis
Ans —- 1
Liver appear dark in opposed phase of chemical imaging
Evaluation of fat with magnetic resonance imaging (MRI) is common by chemical-shift imaging (CSI)principal, where MRI detect different resonance frequencies between protons bound to water and fat. In a regular MRI sequence, images in “in-phase (IP)” and “opposed phase (OP)” are produced at specific echo times when water and fat signals are added and subtracted. This can produce a qualitative or semi-quantitative assessment of hepatic steatosis. In the presence of fatty liver, the liver will appear dark in opposed phase due to signal loss.
Subsequently, dual-echo CSI was developed for fat quantifi- cation based on a pair of OP and IP images, but there were biased from T1- and T2*-relaxation effects. To improve accu- racy, T1-independent, T2*-corrected proton density fat frac- tion (PDFF) methods were developed based on multiple-echo CSI that acquire three or more consecutives pairs of OP and IP echoes.
MRI-PDFF method can assess the fat content of the entire liver in a short breath-hold, in about 20 s. The MRI-PDFF technique has high accuracy in evaluating liver steatosis. The AUROC for diagnosing hepatic steatosis ≥ 5% with his- tology as reference standard has been reported to be 0.98 in a recent meta-analysis
Q. All are true regarding role of Computed Tomography in evaluation of hepatic steatosis except
a.attenuation value of hepatic parenchyma is reduced
b.usually performed using unenhanced CT scan
c.has poor sensitivity to detect mild steatosis
d.routine tool for quantification of hepatic steatosis
Ans —d
Hepatic steatosis evaluation by computed tomography (CT) scan is based on the measurement of attenuation value of liver parenchyma, using Hounsfield units (HUs). Different tissue composition will have different attenuation value in HUs, for example, it is usually − 100 HU for fat and around 30– 40 HU for soft tissue.
With hepatic steatosis, the attenuation value of the liver parenchyma is reduced .Absolute liver attenuation value is developed as a quantitative method to measure steatosis . This is generally performed using unenhanced CT scan to avoid the potential changes in attenu- ation after contrast injection despite some studies reporting similar efficacy with contrast-enhanced CT. However, the ac- curacy of the absolute attenuation value for the quantification of hepatic steatosis may be limited by intra- and inter-scanner variability Established quantitative CT techniques of measuring liver-to-spleen attenuation ratio (CT L/S) limit the variability. In these techniques, the spleen, which generally has a lower attenuation value, is used as an internal control.
CT has been reported to be reasonably accurate in diagnosing moderate to severe steatosis but lack the sensitivity to detect mild steatosis.The sensitivity of CT in de- tecting hepatic steatosis ≥ 5% has been reported to be 50.5 to 67.7% using the MRI-PDFF as reference standard
More importantly, the ionizing radiation from CT deters clinician in using it as a routine tool for quantification of hepatic steatosis. The assessment of hepatic steatosis by CT is usually limited to patients who have undergone CT scan for other reasons or to potential liver donor who will need a CT scan of the liver for pre-operative assessment.
Q.All are true regarding Nonalcoholic fatty liver disease (NAFLD) except
1.the leading cause of chronic liver disease in the world
2.The global prevalence of NAFLD about 25 percent
3.poorly associated with obesity
4. an increased mortality rate mainly due to cardiovascular disease
Ans —-3
NAFLD is closely associated with obesity and it is liver manifestation of metabolic syndrome
Q .All are true regarding NAFLD except
1.USG is first line of investigation
2.Liver biopsy is the gold standard of diagnosis
3.USG is accurate in diagnosing mild fatty liver
4.MRS is used as reference standard
Ans—-3
Ultrasonography (US) for assessment of hepatic steatosis is commonly qualitative in nature.US is reliable and accurate in de- tecting moderate-to-severe fatty liver with sensitivity of 84.8% and specificity of 93.6%
US has several limitations—highly operator-dependent , has poor accuracy in diagnosing mild steatosis and may be less accurate to diagnose steatosis in patients with under- lying hepatic fibrosis.
A recent study revealed that the sensitivity of US was only 65.1% when compared with mag- netic resonance imaging proton density fat fraction (MRI- PDFF) in diagnosing mild steatosis .
To improve the ac- curacy, computer-assisted quantitative US techniques have been developed for the assessment of hepatic steatosis .The most widely reported technique is the computerized hepatorenal index .
However, a more recent study suggested that the hepatorenal ratio was not as good, while acoustic structure quantification (ASQ) from ultrasound echo amplitude was better for the assessment of hepatic steatosis.
Overall, US remains the first-line imaging used to diagnose NAFLD as it is noninvasive, widely available, and relatively inexpenve
1.The sonographic appearance of the
kidneys in the neonate differs from that in older children in respect of
a.more lobulation
b.much less renal sinus
echogenicity
c..very echogenic cortex
d.CM differentiation extremely
well
e.cortex thicker relative to
the size of pyramid
ans 1.e
Neonates have much less renal sinus fat than
in older children, and the central renal sinus echogenicity is uncommonly
appreciated at this age.
The immature neonatal cortex is very echogenic; in contrast to
that in older children, it is hyperechoic relative to the liver—even more so in
premature neonates. Because of this, sonography depicts corticomedullary
differentiation extremely well .Postnatally, the echogenicity of the cortex
gradually decreases, and it is usually hypoechoic relative to the liver by 4
months of age, but occasionally this process takes until 6 months.
Normal renal pyramids are
hypoechoic relative to the renal cortex, independent of patient age, and are
more echogenic than normal urine in the collecting system, which is anechoic .
Compared with the cortex in older children, the immature cortex in
the neonate is thinner relative to the size of the pyramids. Therefore, the
pyramids appear relatively large .
To those unfamiliar with this normal neonatal appearance, the
relatively large, normal, hypoechoic pyramids may be misinterpreted as dilated
calices or renal cystic disease and the relatively thinner hyperechoic cortex
may be misinterpreted as cortical scarring or even ischemic changes.
Figure . Normal sonographic appearance of the renal pyramids in young infants. (a) Transverse sonogram of a neonatal kidney shows good corticomedullary differentiation. The hypoechoic pyramids normally appear
relatively large at this age. (b) Focused longitudinal sonogram of a kidney, obtained with a linear-array transducer,
shows striations of the parenchyma, which are better appreciated in the cortex than in the pyramids.
The echogenic structures (arrows) represent the collapsed fornices of the calices (which are not distended with urine) together with some renal sinus fat.
All are true regarding bain tumour except
1.increased emphasis on molecular and genetic data in updated 2016 WHOCNS tumour classification
2.Sonic hedgehog activated medulloblastoma generally have good prognosis
3.diffuse leptomeningeal glioneuronal tumour
and multinodular and vacuolating tumour of cerebrum added as new entities
4. 2 hydroxy glutarate spectroscopy in infiltrating glioma may be useful
5.1p/19q codeletion is seen in astrocytoma
And -- 5
1p/29q codeletion is seen in oligodendroglioma
Q. Brain tumor may harbor mutations in the genes for the isocitrate dehydrogenases (IDH) and produce 2 - hydroxyglutarate which may be identified by imaging and help in characterization of tumor . Identify the tumor 1.Infiltrating gloms 2.infiltrating meningioma 3.infiltrating medulloblastoma 4.infiltrating teratoma 5.infiltrating ependymoma Ans ——- 1 .
For the WHO 2016 revision, IDH mutation has become definitional for infiltrating gliomas in adults, with 1p/19q codeletion further characterizing the type .Oligodendroglioma is an infiltrating glioma that carries both IDH mutation and 1p/19q codeletion (which does not occur in the absence of IDH mutation). Astrocytoma is an infiltrating glioma that is subdivided in the classification by the presence of IDH mutation and never contains 1p/19q codeletion. REF —- Radiographics
1.What is the finding in above image
2.what is the ideal time for such scan?
3.What are causes of such finding ?
4. What is mode of management of such cases?
