Introduction to Genitourinary Radiology, Part II

In this video lecture, we “leave no stone unturned” as we introduce both renal and bladder calculi. Also, the basics of renal mass evaluation with ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) are discussed.
Topics include:
1) The importance of Hounsfield unit density when describing renal calculi.
2) CT and ultrasound appearance of nephrouterolithiasis and renal obstruction.
3) Basic retroperitoneal fascial plane anatomy.
4) Techniques to optimize stone detection with ultrasound.
5) How to identify whether you are looking at a T1- or T2-weighted MRI sequence.
6) Differentiating simple and hyperdense renal cysts from neoplasm with CT and MRI.
7) The importance of MRI subtraction imaging.
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[@BB_Ye]

I think there is a delay regarding video and sound. Particularly noticeable at the end

[@Rasha.Al-Khafaj]

Great video. Thank you, and keep up the excellent work. I appreciate it 😀

[@Radquarters]

Thank you for the kind feedback!🙂

[@olgaalbulescu6883]

Awesome! Thank you!

[@Admelr]

this been great help , thank you

[@Radquarters]

That's great to hear, thank you.

[@mokhles703]

a superb video.

[@Radquarters]

Thanks so much mokh les!

[@jaisonthomas4493]

Superb classs doc.

[@Radquarters]

Thank you!

[@pranverarama1660]

I have a question regarding the term increased density (after i.v.) and attenuation, if you could clear this up in a simple way. Do you for ex. say that the mass in non-enhancement phase has a density of 9HU, or attenuation of 9HU, and then for the same mass in nephrographic phase do you say it has increased density or increased attenuation? I get myself confused, since shouldn't density of a mass be the same, but the attenuation different with different phases? I apologize if my question is dumb or confusion, but if you could clear this for me, I'd be forever grateful :)
This is confusing when you have to write a report in a different language, since we get lost in translation.

[@Radquarters]

Hi Pranvera Rama, that is definitely not a dumb question! CT attenuation value is defined as the density of a particular material expressed in HUs. On CT, you can *generally* consider attenuation and density as interchangeable. Density is a more generic term that you can use across all modalities, but attenuation is specific to CT. To answer your question, yes, on postcontrast images you could say either that the mass has increased density or that it has increased attenuation, because you are referring to the density of the iodinated contrast taken up by the mass, not the intrinsic physical density of the mass itself. To keep things simple, I often just describe a mass like this: "Mass on noncontrast images has density of 20 HU, increasing to 50 HU on postcontrast images indicating enhancement." In other words, in this scenario I'll just say whether or not the mass is enhancing, rather than add hyperdense/hyperattenuating descriptors. Does that make sense?

[@iimaanbare8559]

Thanks 😊

[@Radquarters]

You're welcome!

[@tenzinangio2744]

A problem in CT, (for me) not just in GU CT but in general is how do I actually call these density measurements valid.
I mean lets say for example we are talking about simple cysts, You see one around 10mm in max diameter it has an average HU of 18, then its 22 the third time is 19 fourth 23, You get my point. When something is really borderline in density(especially smaller lesions around or subcentimeter) do You just tipically take the first number at face value, or do You make whatever amount of measurements and use the average of them. Or are You just on the cautious side and in these cases just order followups, different modalities.
Again not just cysts but in general.
I do realize it is not just a yes or no question and probably there is no definite answer that applies to all situations that's just medicine, still I am curious about the approach of others in the field.

[@Radquarters]

When measuring CT density for renal lesions, I try to make the ROI about half the size of the lesion, and to make sure there is lesion (and not renal parenchyma) in the slices above and below (to avoid volume averaging). It also depends on the size of the lesion, as renal lesions 1.5 cm or smaller are subject to pseudoenhancement. But as you point out, sometimes the density is still borderline, and in those cases I'll also factor in cyst morphology, stability, etc, when deciding if additional imaging is necessary. Hope that helps!

[@rajendrakumarsinghmehra2368]

Excellent presentation , thank you

[@Radquarters]

Thanks for watching!

[@saharaljurany297]

احسنت

[@Radquarters]

Thank you Sahar!

[@prosantabarikder978]

Nice

[@Radquarters]

Appreciate that :)

[@patrickmelville4623]

Audio is off

[@kambizfaridmarandi1858]

After 5 minutes the sound and slides aren't matched

[@Radquarters]

Perhaps there was an issue with your connection?

[@yahyemahamed9011]

@@Radquarters same here

[@BB_Ye]

@@Radquarters I dont think it is the connection or end user error. It looks to be a video formatting error. You might have to reupload the video to TH-cam