ABSTRACT
BACKGROUND: Solitary pulmonary microembolism is rarely discussed as a distinct diagnostic entity. The purpose of this investigation was to determine the prevalence and clinical significance of embolism limited to subsegmental branches in a group of patients discharged from hospital on anticoagulants with a diagnosis of pulmonary embolism based on ventilation-perfusion imaging followed by selective angiography. MATERIAL AND METHODS: Of 29 consecutive patients with classic signs of pulmonary embolism at angiography, we identified a subgroup of 5 patients with sub-segmental embolism, which was solitary in all cases. RESULTS: Clinical presentation included chest pain (2/5), shortness of breath (2/5, or hypoxemia (1/5). Chest X-rays were normal (2/5), or showed pulmonary oedema (1/5) or atelectasis with (1/5), or without (1/5) pleural effusion. VQ imaging patterns included small subsegmental mismatch (1/5), one segment mismatch (1/5), single (1/5) or triple (2/5) match. The site and size of the microemboli found at angiography were incompatible with the location and severity of symptoms in 4/5 (80%) patients, and with location and extent of Chest X-ray findings and with VQ patterns in all patients. VQ abnormalities were either either disproportionably larger or were non congruent with the vascular territory compromised by the subsegmental embolus. CONCLUSIONS: Sub-segmental pulmonary micro-emboli were always solitary, and not uncommon, comprising 17% of all patients with pulmonary embolism. The location and size of the emboli were inconsistent with clinical, Chest X-ray and scintigraphic findings, suggesting that isolated microemboli are a serendipitous finding, of no clinical significance.
Subject(s)
Pulmonary Embolism/diagnosis , Pulmonary Embolism/epidemiology , Risk Assessment/methods , Adult , Aged , Canada/epidemiology , Female , Humans , Male , Middle Aged , Pulmonary Embolism/diagnostic imaging , Radiography , Radionuclide Imaging , Risk Factors , Severity of Illness IndexABSTRACT
The objectives of this study were to determine if diagnostic certainty on angiography correlates with scintigraphic probability for the diagnosis of pulmonary embolism. From a total of 160 consecutive patients who underwent both nuclear imaging and invasive selective pulmonary angiography, we reviewed the xenon-133 ventilation images in 2 posterior oblique views and the Tc-99m macroaggregated serum albumin perfusion scans and angiograms of 40 patients (15 men, 25 women; average age 57 years) who were discharged from the hospital on anticoagulants with a diagnosis of pulmonary embolism. The angiograms were reviewed and the diagnosis of embolism was considered certain in the presence of an intraluminal filling defect, a trailing embolus, or a branch occlusion equal to or larger than a segmental branch (n=29; 73%), and uncertain when the studies were reinterpreted as either equivocal or negative or in the presence of a single, small subsegmental filling defect of questionable clinical significance. The ventilation-perfusion scans were read as high (n=18; 45%), intermediate (n=10; 25%), or low (n=12; 30%) probability. The proportion of patients with diagnostic certainty on angiography in the high-, intermediate-, and low-probability scintigraphic subgroups was, respectively, 100% (18 of 18), 70% (7 of 10), and 33% (4 of 12) (P=0.004). In patients diagnosed with pulmonary embolism based on selective angiography, a lower probability of pulmonary embolism on ventilation-perfusion scintigraphy correlates with a lesser degree of diagnostic certainty on angiography and a higher incidence of single subsegmental emboli.