Value of perfusion lung scan in the diagnosis of pulmonary embolism: results of the Prospective Investigative Study of Acute Pulmonary Embolism Diagnosis (PISA-PED).

Abstract

To assess the value of perfusion lung scan in the diagnosis of pulmonary embolism, we prospectively evaluated 890 consecutive patients with suspected pulmonary embolism. Prior to lung scanning, each patient was assigned a clinical probability of pulmonary embolism (very likely, possible, unlikely). Perfusion scans were independently classified as follows: (1) normal, (2) near-normal, (3) abnormal compatible with pulmonary embolism (PE+: single or multiple wedge-shaped perfusion defects), or (4) abnormal not compatible with pulmonary embolism (PE-: perfusion defects other than wedge-shaped). The study design required pulmonary angiography and clinical and scintigraphic follow-up in all patients with abnormal scans. Of 890 scans, 220 were classified as normal/or near-normal and 670 as abnormal. A definitive diagnosis was established in 563 (84%) patients with abnormal scans. The overall prevalence of pulmonary embolism was 39%. Most patients with angiographically proven pulmonary embolism had PE+ scans (sensitivity: 92%). Conversely, most patients without emboli on angiography had PE- scans (specificity: 87%). A PE+ scan associated with a very likely or possible clinical presentation of pulmonary embolism had positive predictive values of 99 and 92%, respectively. A PE- scan paired with an unlikely clinical presentation had a negative predictive value of 97%. Clinical assessment combined with perfusion-scan evaluation established or excluded pulmonary embolism in the majority of patients with abnormal scans. Our data indicate that accurate diagnosis of pulmonary embolism is possible by perfusion scanning alone, without ventilation imaging. Combining perfusion scanning with clinical assessment helps to restrict the need for angiography to a minority of patients with suspected pulmonary embolism.

The value of computed tomographic obstruction index in the identification of massive pulmonary thromboembolism

“…For definitive diagnosis, clinical evaluation should be considered together with an objective method (9,10). Currently, the Wells, Geneva, Modified Geneva and Miniati scoring systems formulated based on risk factors and clinical findings have been used in the diagnosis of PTE (7,(11)(12)(13). When the findings were scored and the threshold of the Wells scoring system with numerical limits was defined, higher sensitivity and lower negativity rates were reported.…”

Good clinical practice in pulmonary embolism diagnosis: where do we stand today?

“…Moreover, previous probabilistic interpretation criteria and the associated reporting methods, according to PIOPED or modified PIOPED, are unsatisfactory [3]. Using PISAPED criteria with clear answers, taking into account vascular anatomy of the lung has clearly improved diagnosis [4]. Efficient lung scintigraphic methods routinely incorporate ventilation studies.…”

O desafio de diagnosticar tromboembolia pulmonar aguda em pacientes com doença pulmonar obstrutiva crônica

“…(20)(21)26) Criteria for excluding a diagnosis of PTE include normal or quasi-normal perfusion scan, normal pulmonary arteriogram (despite a 3% rate of false-negative results and interobserver discrepancy for subsegmental emboli), inconclusive V/Q mapping results accompanied by negative DVT studies, negative multidetector-row CTA (to be confirmed); and normal levels of the D-dimers associated with low clinical probability. (20)(21)(26)(27)(28) Developing pretest suspicion based on an accurate clinical evaluation is an essential stage in the diagnostic process, facilitating the posttest definition and resulting in a better cost-effectiveness ratio. However, as evidence of the difficulties of developing a solid suspicion, various quite well-delineated prospective studies have demonstrated that objective confirmation of PTE is below 40% among suspected cases, (27)(28)(29) and that approximately 70% of PTE cases diagnosed during autopsies were not previously suspected by the attending physicians.…”

“…(20)(21)(26)(27)(28) Developing pretest suspicion based on an accurate clinical evaluation is an essential stage in the diagnostic process, facilitating the posttest definition and resulting in a better cost-effectiveness ratio. However, as evidence of the difficulties of developing a solid suspicion, various quite well-delineated prospective studies have demonstrated that objective confirmation of PTE is below 40% among suspected cases, (27)(28)(29) and that approximately 70% of PTE cases diagnosed during autopsies were not previously suspected by the attending physicians. (30) …”