Saturday, July 31, 2010

Ultrasound imaging of nuchal thickness ( nuchal translucency thickness): 11 to 13 weeks fetal scan

Ultrasound imaging of the fetus in the period from 11 weeks to 13 weeks 6 days gestational age is important to study fetal nuchal translucency or nuchal thickness. Nuchal translucency is the hypoechoic area in the subcutaneous region in the posterior aspect of the fetal neck. This hypoechoic area represents fluid collection in the nuchal region. The normal amount of fetal nuchal thickness can be upto 2 mm. (at 11 weeks). The normal nuchal translucency thickness can increase to about 2.8 mm. by 13 weeks 6 days. The above ultrasound image shows a sagittal section of the fetal neck with nuchal tranlucency or nuchal thickness of     1.8 mm. in a 11 week old fetus.  This was a normal study. Note the separate band posterior to the neck- the amnion, a membrane present around the fetus. The amnion must be separately identified from the nuchal skin to prevent wrong measurement of the nuchal thickness.

A zoomed view of the nuchal thickness in the same fetus. Note the close proximity of the amniotic membrane.

The normal nasal bone is also visualized in this ultrasound study (see image above). All above images are courtesy of Dr. Prasenjeet Singh, India.
This site gives more information on this topic:

Thursday, July 29, 2010

The glomus body and its tumors:

The glomus body is a unique receptor or rather a thermal sensor found mainly in the dermis of the skin. This is a strange kind of tissue, microscopic in size but with a very important function, somewhat akin to the sensors found inside the room air conditioner. It acts as a sensor detecting changes in temperature of the environment and passes this information up the nervous system resulting in shunting of blood away from the skin by vasoconstriction (shrinking the diameter of the capillaries in the skin) when the surroundings turn cool. This simple mechanism prevents loss of heat during the winter and cool weather. The opposite happens during warm weather. Perhaps we don't realize the importance of these tiny nodes in the skin until it malfunctions. Perhaps the most common pathology of this node is in the distal part of the fingers- the subungual region (the part between the finger nail and the underlying phalanx or bone). This condition is the glomus tumor, a very vascular growth, some call it a hamartoma of the glomus body.
See- , where I discuss this pathology in detail with color Doppler and ultrasound imaging of this rather poorly understood and still relatively unexplored pathology. 

 The grey scale B-mode ultrasound image above shows a typical glomus tumor, seen as a hypoechoic, soft tissue mass beneath the fingernail.
The color Doppler image above shows the vascular nature of the subungual glomus tumor in the 2nd finger.Note the erosion of the underlying bone. Both above images are courtesy of Shlomo Gobi, Israel.

Wednesday, July 21, 2010

Ureterocele with ureteric jet:

Does a ureterocele prevent urine entering into the urinary bladder? This Color Doppler ultrasound image proves that ureteroceles may not always produce ureteral obstruction. Despite the large size of the outpouching of the distal end of the ureter seen in this image, there is a powerful jet of urine being pumped into the urinary bladder (the urine jet is seen as a colored column in the bladder). For more images on this topic see:
This color Doppler ultrasound image is courtesy of Dr. Prasenjeet Singh, MD, India.
And here is another case- a middle aged female patient with pain in the left iliac region:
Grey scale ultrasound image shows a small right ureterocele:
In addition there is a mild hydronephrosis of the right kidney.

This ultrasound video clip confirms the right ureterocele. Very often such an appearance can be mistaken for mucosal edema around a recently passed vesico-ureteric junction calculus. But this is ruled out ---

 There is no mistaking the small bulging vesicle (bubble) of the right ureterocele that measures about 9 mm. at maximum width; gradually collapsing as it empties.

This color Doppler video clip (below) shows normal flow (ureteral or ureteric jet) from the left ureteric orifice. However there is very poor flow from the right ureteric orifice (due to the ureterocele). This is in direct contrast to the case -1 above, where the ureterocele does not cause significant obstruction, despite its large size. 
Moral: size does not always matter when it comes to ureteroceles!!
CASE- 3:
Here is another example of a moderately large right ureterocele, with an almost normal right ureteric urine jet:
I posted this gray scale ultrasound video clip on you tube for better clarity and resolution of the video clip:

And here is the color Doppler video clip of the same case, posted by me on you tube:

This ultrasound image shows both normal kidneys, a clear sign that there is little by way of obstruction to the flow of urine on the side of the ureterocele.

Tuesday, July 20, 2010

Color Doppler video clips of umbilical vein varix

Here are some nice ultrasound and Color Doppler video clips of a 33 week fetus with intra-abdominal umbilical vein varix.

Another Doppler ultrasound video clip:

BL= fetal urinary bladder. VAR= intra-abdominal umbilical vein varix.
Note the close relation of the varix to the urinary bladder. On grey scale ultrasound, the varix may be mistaken for the fetal urinary bladder or a diverticulum from the bladder. (See ultrasound images below):

Spectral Doppler ultrasound trace shows typical venous flow in the varix, albeit turbulent. (See ultrasound picture below).
The turbulent flow within the varix is also seen in the Doppler video clips above.

Saturday, July 10, 2010

Axillofemoral graft

This elderly female patient underwent an axillofemoral graft (also called axillofemoral bypass graft) for loss of blood flow in the right femoral artery. The procedure involved connecting the right femoral artery and right axillary artery using an artificial graft tube, which was placed along the subcutaneous plane of the chest and abdomen. This patient underwent Color Doppler imaging to assess the condition and flow in the graft tube. The color Doppler image above shows the artificial axillofemoral graft tube with normal flow through it. Note the large diameter of the graft tube and location in the subcutaneous plane of the chest wall.

Friday, July 09, 2010

Bilateral urinary calculi- an unusual case

This was a rather unusual case. This elderly male patient complained of pain in the flanks. He was suspected to have lower urinary tract obstruction (meaning a prostate enlargement). Ultrasound imaging of the kidneys (above) show bilateral moderate hydronephrosis, with more severe changes in the left kidney (right half of image). The image shows a large calculus of 2.3 cms. lodged in the left pelvi-ureteric junction (uretero-pelvic junction). But what is the cause of the right hydronephrosis?

The cause of the right hydronephrosis is now obvious- 2 calculi are seen at the right vesico-ureteric junction.

TRUS (transrectal ultrasound) examination confirms the findings. Arrows show 2 calculi in the distal most part of the right ureter (in the vesico-ureteric junction).

Despite the urinary bladder being nearly empty, the right vesico-ureteric junction calculi are seen on TRUS image (only one of the 2 calculi see in this image). The prostate itself only showed mild hypertrophy. This is the first case I stumbled upon with a VUJ (vesico-ureteric junction) and UPJ (uretero-pelvic junction) calculi in the same patient.
See this page for more: