The principles and clinical applications of DTPA and DMSA are as follows:

Principles of DTPA (Diethylene-triamine-penta-acetic Acid):

• DTPA is a chelating agent that forms soluble complexes with metal ions.
• In nuclear medicine, 99mTc-DTPA is used as a radiopharmaceutical that is predominantly excreted by glomerular filtration.
• It can measure glomerular filtration rate (GFR) and assess renal blood flow and function by dynamic imaging after intravenous injection.
• DTPA allows functional renal imaging, tracking clearance and filtration efficiency.

Principles of DMSA (Dimercapto-succinic Acid):

• DMSA is a radiopharmaceutical used for morphological renal imaging due to its cortical binding.
• It binds to renal cortical tissue, allowing high-resolution imaging of renal morphology and scarring.
• It is used primarily to detect acute pyelonephritis, renal scarring, and anatomical abnormalities.

Clinical Applications:

• DTPA scan is important for functional assessment of the kidneys including GFR measurement, renal perfusion, and detection of obstructive uropathy or renovascular hypertension.
• DMSA scan is used for morphological assessment, identifying renal scars, pyelonephritis, hypoplasia, agenesis, and cortical defects.
• In pediatric urology, DTPA is used to evaluate renal function, while DMSA is preferred for evaluating renal scarring and infections.

In summary, DTPA focuses on renal function evaluation via filtration and perfusion imaging, while DMSA assesses renal cortical morphology and scarring in clinical practice, especially in pediatric urology cases.