The "stripe sign" is defined as a rim of perfused lung tissue between the perfusion defect and the adjacent pleural surface. The presence of the sign excluded the diagnosis of PE within the affected zone in 93% of cases. Therefore, perfusion defects which demonstrate a stripe sign are unlikely to be due to PE and in the absence of perfusion defects elsewhere should be interpreted as representing a low probability for PE. Patients with partially resolving perfusion defects may have a similar appearance to the stripe sign, therefore this sign should be interpreted with caution in patients with more chronic symptoms.

Finally, the nuclear medicine physician's subjective estimate of the likelihood of PE (without using specific interpretation criteria) correlated well with the fraction of patients with angiographic evidence of PE. Thus, experienced readers (such as the PIOPED investigators) can provide an accurate estimate of the probability of PE based on radiographic and scintigraphic findings.

Figure 8. Diagnostic algorithm for suspected pulmonary embolism. (US = compression venous ultrasound, IPG = impedance plethysmography, CT = computed tomography.

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