The value of spiral computed tomographic pulmonary angiography and its relationship with clinical and laboratory data in the diagnosis of pulmonary embolism

SUMMARYTHE VALUE OF SPIRAL COMPUTED TOMOGRAPHIC PULMONARYITS RELATIONSHIP WITH CLINICAL AND$1*ø2*5$3+< $1'LABORATORY DATA IN THE DIAGNOSIS OF PULMONARY EMBOLISMPulmonary thromboembolism (PTE) is a common disorder associated withconsiderable mortality. The diagnosis of PTE remains one of the difficult problem confrontingclinicans. Although PTE can accurately be diagnosed with pulmonary angiography, it isexpensive, invasive and have risk of complications. So recently, spiral computed tomographicpulmonary angiography (SCTPA) was used to diagnose PTE because it is relativelynoninvasive, fast and effective technique. Studies aiming to construct appropriate diagnosticalgorithms using non-invasive diagnostic methods are still in practice.The aim of this study was to investigate the role of SCTPA in the diagnosis of PTEand its relationship with the Geneva clinical rules. The discriminatory role of PTE riskfactors, clinical signs and symptoms, arteriel blood gas values, chest radiography andtransthorasic echocardiography findings in patients with or without PTE were also elucidated.Sensitivity, spesifity, positive and negative predictive values of D-dimer test, and positive andnegative predictive values of venous Doppler ultrasonography for the diagnosis of PTE wereanalyzed. The relationship of pulmonary artery diameters with PTE was examined. Lungparenchymal and pleural findings were evaluated for their value in the diagnosis of PTE. Thepitfalls causing misdiagnosis in PTE during SCTPA were defined. Pulmonary arterialcomputed tomography obstruction index ratio (PACTOIR) was calculated for each patienthaving PTE and the relation between PACTOIR with Geneva clinical probability and patientsurvey was investigated.Spiral computed tomographic pulmonary angiography images scans of 90 patientswith suspicion to have PTE were retrospectively reviewed for the presence of PTE by twoindependent radiologists. First radiologist was experienced in thorasic radiology and thesecond was a general radiologist. Presence of PTE was established by consensus of tworadiologists. IQWHUREVHUYHUDJUHHPHQWRQ37(ZDVYHU\JRRGBut two patients whohad poor arterial opacification were excluded from the study in consensus. Finally PTE wasdiagnosed in 37 patient (42%) and was excluded in 51 patient (58%).None of the clinical signs and symptoms was statistically significant for PTE. Chestpain alone were observed in patients without PTE rather than patients with PTE (p:0,019).Malignancy was seen in patients with PTE rather than than patients without PTE (p:0,035).Arteriel bood gas averages were found to be indiscriminative for PTE. Tricuspit insufficiencywith pulmonary hypertension detected on transthorasic echocardiography was the onlyfinding that was meaningful for PTE. None of the signs on chest radiography sign weremeaningful for PTE. D-dimer had a sensitivity of 94%, specifity of 27%, positive predictivevalue of 48%, and negative predictive value of 87%, while venous Doppler ultrasonographyhad a positive predictive value 100%, negative predictive value 33,3% for the diagnosis ofPTE.According to Geneva rules 27,2% of the patients had high, 52,3% had intermadiate,%20,5 had low probability in terms of the PTE. Only high clinical probability group had acorrelation to PTE (p:0,003). The average of PACTOIR of patients with PTE was %33,98 (standard deviation ± 25,05). The average PACTOIR showed significant difference betweenclinical probability groups (p:0,000).The most encountered finding concerning lung parenchyma on SCTPA of patientswith PTE was atelectasis. Among all of the parenchymal signs, only wedge shaped opacitywas encountered in patients with PTE rather than those without PTE (p:0,016). The averageof PACTOIR showed significant difference between patients with or without wedge shapedopacity (p:0,000). No statistically sigificant difference was found in the frequency of pleuraleffusions between patients with or without PTE. On behalf of the measurements of pulmonaryartery, no significant difference was found in the pulmonary artery diameter ratio betweenpatients with PTE and patients without PTE.Six patient had died in our study group. All of these patients were within the highclinically probability group and five of them had PTE. Four patient with PTE had 75%PACTOIR and the other had 7,5% PACTOIR. The patient without PTE was supposed to diebecause of congestive heart failure. The patient, with PTE and 7,5% PACTOIR, the cause ofdeath was tumor burden of acute myeloblastic leukemia. In the remainder the cause of deathwas PTE.In conclusion, clinical signs, symptoms and laboratory results were found to beinadequate for the diagnosis of PTE. Determination of the clinical probability is moreaccurate than empirical assesment for PTE diagnosis. But this study showed that low andintermediate clinical probabilities may not exclude the diagnosis of PTE and requires imagingstudies. Nowadays SCTPA has been accepted to be an effective diagnostic tool in thediagnosis of PTE. The results of SCTPA are mainly reported as negative or positive for thepresence of PTE. Unfortunately almost no attempt has been made to report the amount oftrombuse involving the pulmonary arteries. Pulmonary arterial computed tomographyobstruction index ratio may demonstrate the amount of thrombus, and by menas of the index,clinicians may predict the prognosis of the patient with PTE.