FREQUENCY OF TNANSDUCER FOR SKIN USG

---Frequency of transducers used for examination of skin -----20 to 100 MHz ( depth of field 1 mm or less ,and in -plene resolution  is as high as < 50 micrometere).
---An adequate assesment of subcutaneous tissue can be made by means of transducers of 5 to 15 MHz.
--At 20 MHz ,the echogenic dermis can be separated from the hypoechoic subcutaneous fat .
---
----The thick subcutaneous fat of the lateral part of the proximal thigh can be examined by transducer of as low frequency as 5 MHz.
---Subcutaneous tissue appears as  USG as a discrete hypoechoic layer characterised by a hypoechoic background of fat and hyperechoic linear echoes correspomding to a web of connective tissue
----subcutaneous vein and nerve can be appreciated on USG.
----Normal Lymphatics in the subcutaneous tissue cannot be visualised with US.

GEYSER SIGN

----The geyser radiographic sign on shoulder arthrogram is characterized by leakage of dye from the glenohumeral joint into the subdeltoid bursa. The dye outlines the acromioclavicular joint. It is usually an indication of a full-thickness cuff tear of long duration

-----The geyser sign is an infrequently encountered imaging sign that was originally described on conventional fluoroscopy-guided shoulder arthrography.

----- The sign derives its name from its geyser-like appearance. On imaging, owing to a full-thickness SST tear, synovial fluid or intra-articular contrast extravasates from the glenohumeral joint into the subacromial bursa. The fluid, which then passes through the AC joint into an overlying cystic mass, is said to resemble a geyser spouting upwards.

-----Passage of fluid from the glenohumeral joint into the acromioclavicular joint on arthrography is referred to as the geyser sign. It can be seen with chronic rotator cuff tendon tear or after injury of the acromial undersurface during surgery.

FROM -----MANY SOURCES

CHASING HCC THROUGH MCQ

Q.All are true regarding hepatocellular carcinoma except

a.result of defferentiation through regenerative nodules to dysplastic nodules to HCC

b.regenerative nodules and dysplastic nodules are predominantly supplied by portal vein

c.HCC is solely supplied by abnormal ,unpaired hepatic arteries

d.HCC doesnot have portal blood supply  

e.HCC is commonly diagnosed on basis of histological confirmation

ANS---e

Hepatocellular carcinoma differs from most malignancies because it is commonly diagnosed on the basis of imaging features alone, without histologic confirmation

4.All are true regarding AASLD recommendation of  HCC except

a.US surveillace every 6 months in cirrhosis patients

b.new nodules > 1cm is suspicious of HCC

b.nodules stable for 2yrs should undergo routine surveillance

d.suspicious nodules require further investigation by Multiphasic CT/MRI

e.arterial phase washout

ANS.---e

Portal veinous or delayed washout is seen in HCC

Q.All are true regading AASLD criteria for diagnosis of HCC in cirrhosis

a.use of multiphasic CT/MRI

b.arterial hyperattenuation of lesion

c.portal venous phase hypoattenation of thelesion

d.delayed phase hyperatenuation of the lesion

e.portal veous phase /delayed phase washout

ANS.---d

---The radiologic diagnosis of hepatocellular carcinoma can be made at either CT or MR imaging, provided that a multiphasic contrast material–enhanced study is used.

----Characteristically, hepatocellular carcinoma enhances during the arterial phase because of its blood supply from abnormal hepatic arteries. Contrast medium in the surrounding liver parenchyma is diluted during this phase because the parenchymal blood supply arises mostly from the portal veins, which are not yet opacified. 

-----In the portal venous phase, the surrounding liver parenchyma becomes relatively hyperattenuated and the lesion is perceived to be hypoattenuated because of its lack of portal venous supply. This appearance is the so-called washout effect. Occasionally, washout is evident only during a delayed phase sequence.

------ Thus, a four-phase imaging study is required: non–contrast-enhanced phase, arterial phase, portal venous phase, and delayed phase

 ----- Images should be acquired in four phases: non–contrast-enhanced phase (before the injection of contrast material), late arterial phase (about 20 seconds after the injection), portal venous phase (50 seconds after the injection), and delayed phase (>120 seconds after the injection). 

-----The optimal timing for image acquisition in the delayed phase is debated, varying between 2 and 15 minutes after contrast material injection. 

------Contrast-enhanced US studies have shown that approximately 90% of hepatocellular carcinomas demonstrate washout by 5 minutes after injection of the microbubble contrast agent . Use of a 5-minute delay may be the practical choice for the timing of the delayed phase.

-----Precontrast and dynamic postcontrast T1-weighted three-dimensional fat-suppressed gradient-echo sequences are required, in addition to T2 (with and without fat saturation) and T1 in-phase and opposed-phase imaging. Timing of the dynamic contrast-enhanced sequences is the same as that used for the CT examination. Emphasis on precise breath-holding is extremely important.

-----Systematic review has shown that MR imaging is more sensitive than CT in the diagnosis of hepatocellular carcinoma (81% vs 68%) 

ECHOES OF HEPATOCELLULAR ADENOMA

Q.Hyperechogenicity of Hepatocellular adenoma is

 due to

a.fat only

b.glyogen only

c.air only

d.fat and glycogen

e.fat and air

1ANS.---d

HOW MUCH WE HAVE FORGOTTEN?--------FROM CLASS IX NCERT BOOK

Q.Who discovered canal rays ?

a.J.J. Thomson

b.E.Rutherford

c.E.Goldstein

d.Neils Bohr

ANS.----c

Q.What is canal rays?

a.positively charged radiations in a gas discharge

b. negatively charged radiations in a gas discharge

c. electrically neutral  radiations in a gas discharge

d.none of the above

ANS.----a

HCC-----summary from radiographics (2013),VOLUME 333,ISSUE 6

HCC

----Hepatocellular carcinoma is increasing in frequency. 

----It is a malignancy encountered mainly in the setting of cirrhosis; therefore, US surveillance and monitoring of AFP levels are recommended for patients with cirrhosis. 

---- The detection of focal liver lesions larger than 1 cm at routine US surveillance requires immediate further investigation with multiphasic CT or MR imaging. 

-----The characteristic imaging appearance of hepatocellular carcinoma is its enhancement pattern: arterial phase hyperenhancement and venous or delayed phase washout. 

-----The diagnosis of hepatocellular carcinoma can be made from a single imaging study when the characteristic enhancement pattern is demonstrated. 

----The BCLC system is the staging system of choice because it combines validated predictors of survival and links staging with treatment options. Stages are not determined on the basis of radiologic findings alone; imaging information is combined with clinical and biochemical parameters.

---- In the future, as classification systems evolve further, the diagnostic roles of diffusion-weighted imaging and hepatocyte-specific MR imaging contrast media and the therapeutic role of newer interventional techniques will become better defined.