This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Radiology
Stipple sign in transitional cell carcinoma of the renal collecting system is best demonstrated by – 
Select and explain. 
A. Intravenous urography, B. Retrograde pyeloureterography, C. Radionuclide scan, D. Ultrasound scan
A: Intravenous urography
Answer: A: Intravenous urography 
Explanation: The stipple sign refers to tracking of contrast into the interstices of a papillary lesion. This is seen in Intravenous urography (intravenous pyelography) of transitional cell carcinoma of renal collecting sysym. Other signs on IVP are filling defect; Calyceal obliteration & amputation; hydronephrosis with soap bubble nephrogram.