Leg ischemia: assessment with MR angiography and spectroscopy.
OBJECTIVE
To prospectively determine reproducibility of magnetic resonance (MR) angiography and MR spectroscopy of deoxymyoglobin in assessment of collateral vessels and tissue perfusion in patients with critical limb ischemia (CLI) and to follow changes in patients undergoing intramuscular vascular endothelial growth factor (pVEGF)-C gene therapy, percutaneous transluminal angioplasty, supervised exercise training, or no therapy.


METHODS
Study and gene therapy protocols were approved, and all patients gave written informed consent. To determine repeatability and reproducibility, seven patients underwent MR angiography and five underwent MR spectroscopy. The techniques were used to judge disease progress in 12 other patients with or without therapy: MR angiography to help determine change in visualization of collateral vessels and MR spectroscopy to help assess change in perfusion at proximal and distal calf levels. MR angiographic results were subjectively analyzed by three blinded readers. Intraobserver variability was expressed as 95% confidence interval (CI) (n=7); interobserver variability, as kappa statistic (n=15). Reexamination variability of MR spectroscopy was given as 95% CI for subsequent recovery times, and correlation with disease extent was calculated with Kendall taub rank correlation. Fisher-Yates test was used to correlate changes with pressure measurements and clinical course.


RESULTS
Intraobserver and interobserver concordance was sensitive for detection of collateral vessels. Intraobserver agreement was 85.7% (95% CI: 42.1%, 99.6%). Interobserver agreement was high for small collateral vessels (kappa=0.74, P <.001) and fair for large collateral vessels (kappa=0.36, P=.002). MR spectroscopy was reproducible (95% CI: +/-26 seconds for proximal, +/-21 seconds for distal) and showed a correlation with disease extent (proximal calf, taub=0.84, P <.001; distal calf, taub=0.68, P=.04). Small collateral vessels increased over time (P=.04) but did not correlate with pressure measurements and clinical course. Recovery time correlated with clinical course (proximal calf, P=.03; distal calf, P=.005).


CONCLUSIONS
MR angiography and MR spectroscopy of deoxymyoglobin can help document changes in visualization of collateral vessels and tissue perfusion in patients with CLI.
Baumgartner
Iris
I
Swiss Cardiovascular Center, Division of Angiology and Departments of Diagnostic, Interventional, and Pediatric Radiology, University Hospital Bern, Freiburgstrasse 10, 3010 Bern, Switzerland.
Thoeny
Harriet C
HC
Kummer
Oliver
O
Roefke
Christian
C
Skjelsvik
Corinna
C
Boesch
Chris
C
Kreis
Roland
R
D000368:Aged; D017130:Angioplasty; D003097:Collateral Circulation; D003287:Contrast Media; D018450:Disease Progression; D005081:Exercise Therapy; D005260:Female; D015316:Genetic Therapy; D006801:Humans; D007511:Ischemia / Q000175:diagnosis* / Q000628:therapy; D007866:Leg / Q000098:blood supply*; D018810:Magnetic Resonance Angiography / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008297:Male; D009211:Myoglobin / Q000031:analogs & derivatives* / Q000378:metabolism*; D015588:Observer Variation; D016491:Peripheral Vascular Diseases / Q000175:diagnosis* / Q000628:therapy; D011446:Prospective Studies; D015203:Reproducibility of Results
D003287:Contrast Media; D009211:Myoglobin; C055547:deoxymyoglobin