Can MR measurement of renal artery flow and renal volume predict the outcome of percutaneous transluminal renal angioplasty?

Cardiovasc Intervent Radiol. Jul-Aug 2001;24(4):233-9. doi: 10.1007/s00270-001-0005-y.

Abstract

Purpose: Predicting therapeutic benefit from percutaneous transluminal renal angioplasty (PTRA) in patients with renal artery stenosis (RAS) remains difficult. This study investigates whether magnetic resonance (MR)-based renal artery flow measurements relative to renal parenchymal volume can predict clinical outcome following PTRA.

Methods: The data on 23 patients (13 men, 10 women; age range 47-82 years, mean age 64 years) were analyzed. The indication for treatment was hypertension (n = 18) or renal insufficiency (n = 5). Thirty-four cases of RAS were identified: bilateral disease was manifest in 11 and unilateral disease in 12 patients. The MR imaging protocol included a breath-hold, cardiac-gated cine phase-contrast sequence for renal flow measurement and a fast multiplanar spoiled gradient-echo sequence for renal volume measurement. MR measurements were performed on the day prior to and the day following PTRA. Clinical success was defined as (a) a reduction in diastolic blood pressure > 15% or (b) a reduction in serum creatinine > 20%. Kidneys were categorized as normal volume or low volume. A renal flow index (RFI) was calculated by dividing the renal flow (ml/min) by the renal volume (cm3).

Results: Clinical success was observed in patients. Twelve patients did not benefit from angioplasty. Normal kidney volume was seen in 10 of 11 responders and in 8 of 12 nonresponders, resulting in a sensitivity of 91%, specificity of 33%, a positive predictive value (PPV) of 56% and a negative predictive value (NPV) of 80%. A RFI below a threshold of 1.5 ml/min/cm3 predicted successful outcome with 100% sensitivity, 33% specificity, 58% PPV, and 100% NPV. The combination of normal renal volume and a RFI below 1.5 ml/min/cm3 identified PTRA responders with a sensitivity of 91%, a specificity of 67%, a PPV of 71%, and a NPV of 89%. PTRA resulted in a greater increase in renal flow in responders compared with nonresponders (p < 0.001).

Conclusion: A combination of cine phase-contrast MR renal flow and parenchymal volume measurements enables identification of patients benefiting from PTRA with a high sensitivity and NPV, but only moderate specificity and PPV.

MeSH terms

  • Aged
  • Aged, 80 and over
  • Angioplasty, Balloon*
  • Contrast Media
  • Female
  • Gadolinium DTPA
  • Humans
  • Imaging, Three-Dimensional
  • Kidney / pathology*
  • Magnetic Resonance Angiography
  • Magnetic Resonance Imaging*
  • Magnetic Resonance Imaging, Cine
  • Male
  • Middle Aged
  • Predictive Value of Tests
  • Prospective Studies
  • Renal Artery / pathology
  • Renal Artery / physiopathology
  • Renal Artery Obstruction / diagnosis
  • Renal Artery Obstruction / physiopathology
  • Renal Artery Obstruction / therapy*
  • Renal Circulation*
  • Sensitivity and Specificity
  • Treatment Outcome

Substances

  • Contrast Media
  • Gadolinium DTPA