Muscular scintigraphy at effort and the index of systolic pressure (ISP) at rest in the detection of obliterative arteriopathy of inferior limbs (OAIL)

The diminution of fixation of 201Tl at effort on the leg muscles can reveal a debuting or confirmed OAIL. The same is valid for the ISP. This study compares the 2 techniques in asymptomatic subjects, the ISP being used as 'reference method'. We have measured in 105 patients the ISP at rest (posterior-tibial pressure/humeral pressure, left and right), the asymmetry index (AI), defined as fixation in a limb divided by fixation in the other, and the segmentary fixation index (SFI), defined as fixation in a limb divided by fixation in the entire body, after the injection of 92 MBq of 201Tl at the moment of a maximal effort test, achieved on a running belt. An ISP < 0.90 was considered as pathologic (13/105 i.e. 12.4%). A table is presented, giving the percentage values of AI, SFI and AI + SFI corresponding to the sensitivity, specificity, positive predictive value and negative predictive value. In conclusion, the sensitivity of the muscular scintigraphy at effort in detection of OAIL, characterized by a significant diminished ISP at rest, varies according to the criteria of positivity. The AIs is less sensible but more specific. The sensitivity is maximal (100%) when one couples the 2 indices, to detriment of specificity (55%). The best compromise is provided by the ISF. Although the positivity in case of normal at-rest ISP is rather frequent. The significance of the muscular anomalies detected at effort remains to be elucidated, taking into account the limits of ISP