Diagnosis of pulmonary embolism: comparison of CT angiography and MR angiography in canines

PURPOSE: To compare the sensitivity and specificity of helical computed tomographic angiography (CTA), CTA with multiplanar reconstructions (MPR)/three-dimensional-shaded surface display (3D-SSD), and gadolinium-enhanced magnetic resonance angiography (MRA) for pulmonary embolism (PE) detection. MATERIALS AND METHODS: Gelatin sponge emboli were introduced into the femoral veins of seven dogs and conventional digital subtraction angiography (CA), CTA, and MRA performed. Images from CTA, CTA with MPR/3D-SSD, and MRA were reviewed for the presence of PE in lobar and segmental arteries, and subsegmental zones. Postmortem angiography and CA were the gold standard. RESULTS: There were 50 emboli in the 294 vessels/zones analyzed. The sensitivity of CTA for the two readers was 76% (95% confidence interval [CI]; 64%-88%) and 64% (95% CI; 50%-78%), and for the two MRA readers was 52% (95% CI; 38%-66%) and 48% (95% CI; 34%-62%). CTA was more sensitive than MRA when PE were subdivided by vessel caliber. Specificity was high for CTA and MRA among all readers (98.8%-99.6%). MPR/3D-SSD did not improve results of axial CT. MRA perfusion defects were 46% and 47% sensitive and 100% specific. Interobserver agreement was high for CTA and MRA (kappa 0.92 and 0.93, respectively). The average diameter of vessels with emboli was 3.7 mm +/- 1.06. CONCLUSION: Helical CTA is more sensitive than three-dimensional gadolinium-enhanced MRA for the detection of PE. Both CTA and MRA are highly specific for PE detection and demonstrate high interobserver agreement. MPR/3D-SSD did not increase CTA performance over axial images alone.     

Real-time MR with TrueFISP for the detection of acute pulmonary embolism: initial clinical experience

The feasibility and diagnostic value of real-time magnetic resonance imaging (RT-MRI) for the diagnosis of acute pulmonary embolism (PE) was evaluated by comparing RT-MRI and magnetic resonance angiography (MRA). In 39 consecutive patients with suspected PE real-time true fast imaging with steady-state precession (TrueFisp) was prospectively compared with contrast-enhanced MRA on a 1.5-T MR scanner. The TrueFisp sequence used allowed acquisition of T2-weighted images at 0.4 s per image so that the pulmonary vasculature could be visualized in three orientations in <3 min without the need for breath holding or contrast media application. Results of additional scintigraphic pulmonary perfusion examinations were available from 17 patients. All 39 primary RT examinations (100%) and 30 of 39 MRA examinations (77%) were of diagnostic quality. The reasons underlying failure to achieve diagnostic quality for MRA were breathing artifacts among dyspneic patients in all 9 cases. Compared with MRA, the sensitivities and specificities of RT sequences for PE were 93 and 100% (per examination), 96 and 100% (lobar artery PE), and 97 and 100% (segmental artery PE), respectively. Compared with scintigraphy, the sensitivity and specificity of RT-MRI were 83 and 100%, respectively. The MRA reached 100% sensitivity and specificity in this subgroup. The RT-MRI proved to be very robust and undisturbed by respiratory movements and patient cooperation. Its image quality assured fast diagnostic examinations, and its sensitivity and specificity, compared with MRA and scintigraphy, were sufficient to allow the diagnosis of acute central, lobar, and segmental PE; therefore, the emergency diagnosis of PE using RT-MRI is feasible and reliable.     

Pulmonary MRA: Differentiation of pulmonary embolism from truncation artefact

Purpose

Truncation artefact (Gibbs ringing) causes central signal drop within vessels in pulmonary magnetic resonance angiography (MRA) that can be mistaken for emboli, reducing diagnostic accuracy for pulmonary embolism (PE). We propose a quantitative approach to differentiate truncation artefact from PE.

Methods

Twenty-eight patients who underwent pulmonary computed tomography angiography (CTA) for suspected PE were recruited for pulmonary MRA. Signal intensity drops within pulmonary arteries that persisted on both arterial-phase and delayed-phase MRA were identified. The percent signal loss between the vessel lumen and central drop was measured. CTA served as the reference standard for presence of pulmonary emboli.

Results

A total of 65 signal intensity drops were identified on MRA. Of these, 48 (74 %) were artefacts and 17 (26 %) were PE, as confirmed by CTA. Truncation artefacts had a significantly lower median signal drop than PE on both arterial-phase (26 % [range 12–58 %] vs. 85 % [range 53–91 %]) and delayed-phase MRA (26 % [range 11–55 %] vs. 77 % [range 47–89 %]), p?<?0.0001 for both. Receiver operating characteristic (ROC) analyses revealed a threshold value of 51 % (arterial phase) and 47 % signal drop (delayed phase) to differentiate between truncation artefact and PE with 100 % sensitivity and greater than 90 % specificity.

Conclusion

Quantitative signal drop is an objective tool to help differentiate truncation artefact and pulmonary embolism in pulmonary MRA.

Key points

? Inexperienced readers may mistake truncation artefacts for emboli on pulmonary MRA ? Pulmonary emboli have non-uniform signal drop ? 51 % (arterial phase) and 47 % (delayed phase) cut-off differentiates truncation artefact from PE ? Quantitative signal drop measurement enables more accurate pulmonary embolism diagnosis with MRA     

三维增强磁共振肺动脉血管造影诊断急性肺栓塞的实验研究

目的 探讨钆喷替酸葡甲胺（Ｇｄ－ＤＴＰＡ）三维增强共振肺动脉血管造影成像（３ＤＣＥＭＲＰＡ）在急性肺栓塞（ｐｕｌｍｏｎａｒｙ ｅｍｂｏｌｉｓｍ,ＰＥ）中的诊断价值。方法 对１７只自体血栓引发的犬急性肺栓塞模型,利用３Ｄ快速扰相梯度回波序列（ＦＳＰＧＲ）行３Ｄ ＣＥＭＲＰＡ检查和Ｘ线肺动脉血管造影（Ｘ－ｒａｙ ｐｕｌｍｏｎａｒｙ ａｎｇｉｏｇｒａｐｈｙ,ＸＰＡ）检查,并与病理解剖对照。     

Whole-heart coronary magnetic resonance angiography: value for the detection of coronary artery stenoses in comparison to multislice computed tomography angiography

BACKGROUND: Coronary magnetic resonance imaging and computed tomography are being discussed as alternatives to catheter angiography in the detection of coronary artery disease. Yet, only few comparative validations have been performed. PURPOSE: To compare steady-state free precession whole heart coronary magnetic resonance imaging (MRI) with multidetector coronary computed tomography angiography (CTA) for the detection of coronary artery disease using catheter angiography as the standard of reference. MATERIAL AND METHODS: Twenty patients with known CAD were examined with navigator (NAV) gated and corrected free-breathing 3D balanced gradient echo whole heart coronary MRI and coronary CTA. Subjective overall image quality (4 point scale, 1 = excellent), visibility of vessel segments and accuracy for the detection of significant coronary stenoses (>50%) were compared to coronary x-ray angiography by two blinded readers. RESULTS: Median of subjective image quality was 3 for coronary MRI and 2 for coronary CTA. Of a total of 209 segments, 67 segments (32%) had to be excluded from the evaluation by coronary MRI (61 due to insufficient image quality and 6 due to stent artifacts). For coronary CTA, 31 segments (15%) had to be excluded from the evaluation (12 due to insufficient image quality, 15 due to severe calcifications superimposing the vessel lumen and 4 due to stent artifacts. Segment based values for the detection of >/=50% diameter coronary x-ray angiographic stenoses were: specificity: MRI 88%, CTA 95%; sensitivity: MRI 82%, CTA 84%; diagnostic accuracy: MRI 87%, CTA 93%; positive predictive value: MRI 68%, CTA 77% and negative predictive value: MRI 94%, CTA 95%. CONCLUSION: Coronary WH-MRI was inferior to coronary CTA regarding image quality and number of evaluable segments but both had similar diagnostic value for the detection and exclusion of CAD when only evaluable segments were included.     

Comparison of contrast-enhanced ct angiography and gadolinium-enhanced MR angiography in the detection of subsegmental-sized pulmonary embolism. An experimental study in a pig model

Purpose: 
To compare contrast-enhanced CT angiography (CTA) and gadolinium-enhanced MR angiography (MRA) for the detection of subsegmental-sized pulmonary emboli in a pig model. Material and Methods: 
In 5 anesthetized pigs, 3-mm diameter embolic materials made of Konjac, a semisolid food, were introduced through the internal jugular vein into pulmonary arteries. After embolization, CTA and MRA images were obtained. Respiration was suspended during CTA and MRA image acquisition. Two readers reviewed the CTA and MRA images to detect emboli. The pigs were sacrificed, and sliced specimens of inflated lung served as the gold standard. Results: 
Thirty-six emboli were detected within peripheral arteries. The sensitivity (and 95% confidence intervals) of CTA for the two readers were 57% (39-74%) and 66% (48-81%), and 88% (69-98%) and 92% (74-94%) for MRA. The specificity of CTA was 95% (91-97%) and 98% (96-99%), and that of MRA was 85% (74-93%) and 90% (80-96%). Interobserver agreement was higher for MRA (kappa 0.898) than CTA (kappa 0.574). Conclusion: 
For the detection of subsegmental pulmonary emboli, MRA was superior to CTA, with a higher sensitivity and interobserver agreement by demonstrating perfusion deficits.     

CT imaging in acute pulmonary embolism: diagnostic strategies

Computed tomography pulmonary angiography (CTA) has increasingly become accepted as a widely available, safe, cost-effective, and accurate method for a quick and comprehensive diagnosis of acute pulmonary embolism (PE). Pulmonary catheter angiography is still considered the gold standard and final imaging method in many diagnostic algorithms. However, spiral CTA has become established as the first imaging test in clinical routine due to its high negative predictive value for clinically relevant PE. Despite the direct visualization of clot material, depiction of cardiac and pulmonary function in combination with the quantification of pulmonary obstruction helps to grade the severity of PE for further risk stratification and to monitor the effect of thrombolytic therapy. Because PE and deep venous thrombosis are two different aspects of the same disease, additional indirect CT venography may be a valuable addition to the initial diagnostic algorithm—if this was positive for PE—and demonstration of the extent and localization of deep venous thrombosis has an impact on clinical management. Additional and alternate diagnoses add to the usefulness of this method. Using advanced multislice spiral CT technology, some practitioners have advocated CTA as the sole imaging tool for routine clinical assessment in suspected acute PE. This will simplify standards of practice in the near future.     

肺灌注/通气显像与螺旋CT肺动脉造影诊断肺栓塞的对比研究

目的评价肺灌注/通气显像与螺旋CT肺动脉造影诊断肺栓塞各自的敏感性。方法以肺动脉造影为金标准,并按不同栓塞部位分为叶及段肺动脉、亚段肺动脉两组;按肺动脉狭窄程度分为严重狭窄(超过50%)和轻度狭窄(少于50%)两组。对40例疑肺栓塞患者先后行肺核素显像和螺旋CT肺动脉造影检查,根据分组分别比较两种方法的敏感性。结果①肺动脉造影共确定叶及段肺动脉栓塞102支。其中,肺灌注/通气显像显示86处叶及段性肺灌注/通气不匹配,敏感性为84.3%;螺旋CT肺动脉造影示98支,敏感性为96.1%;②肺动脉造影共确定140支亚段肺动脉栓塞,其中肺灌注/通气显示120处,敏感性为85.7%;螺旋CT肺动脉造影显示115支,敏感性为82.1%;③肺动脉狭窄程度>50%时,通气/灌注显示109处,螺旋CT肺动脉造影显示97支;肺动脉狭窄程度<50%时,通气/灌注显示91处,螺旋CT肺动脉造影显示121支。结论对叶及段肺动脉栓塞,两种方法敏感性基本相同;对亚段肺动脉栓塞,肺灌注/通气显像略高;肺血管轻度栓塞时,螺旋CT肺动脉造影略高。     

A prospective comparison of duplex ultrasonography, captopril renography, MRA, and CTA in assessing renal artery stenosis

PURPOSE: To prospectively compare the diagnostic accuracy of duplex ultrasonography, captopril renography, computed tomography angiography (CTA), and 3D Gd magnetic resonance angiography (MRA) in diagnosing hemodynamically significant renal artery stenosis (RAS). MATERIAL AND METHODS: The standard of reference was measurement of transstenotic pressure gradient. Fifty-eight hypertensive patients with suspicion of RAS were evaluated, when possible, by all five techniques. Sensitivity and specificity to detect RAS were compared for each technique on both a patient and kidney basis. Discrepancies were evaluated separately and classified as borderline, method dependent, or operator dependent. RESULTS: The prevalence of RAS was 77%. The sensitivity/specificity of ultrasonography, captopril renography, CTA, and MRA in detecting kidneys with RAS was 73/71%, 52/63%, 94/62%, and 93/91%, respectively. Ultrasonography had a significantly lower sensitivity than CTA and MRA (P<0.001) but higher than captopril renography (P = 0.013). Borderline RAS was the main cause for discrepancies. CONCLUSION: MRA and CTA were significantly better than duplex ultrasonography and captopril renography in detecting hemodynamically significant RAS. The ultrasonography criteria for RAS based on the evaluation of renal peak systolic velocity and renal/aortic ratio are questionable. Captopril renography cannot be recommended for assessing RAS.     

Non-invasive assessment of neck-vessel pathology

Clinical trials (NASCET, ECTS) have shown that carotid endarterectomy is protective against stroke in patients with symptomatic severe carotid stenosis. To decrease costs and risks, new diagnostic tools have been developed, such as duplex ultrasound (DUS), magnetic resonance angiography (MRA), and more recently computed tomography angiography (CTA). CTA and MRA provide excellent 3D angiography images of the extracranial vessels, using a volume-rendering technique. Digitally subtracted MRA (DSA-MRA) obtained with high-speed acquisitions during gadolinium injection has also recently become available. These techniques are changing the role of non-invasive assessment of carotid stenosis. Although it is probably too early to assess a definite diagnostic algorithm, the use of DSA as a pre-surgical tool for defining carotid stenosis is rapidly decreasing. Received: 9 February 1998; Accepted: 13 February 1998     

Clinical outcomes after magnetic resonance angiography (MRA) versus computed tomographic angiography (CTA) for pulmonary embolism evaluation

Purpose

To compare patient outcomes following magnetic resonance angiography (MRA) versus computed tomographic angiography (CTA) ordered for suspected pulmonary embolism (PE).

Methods

In this IRB-approved, single-center, retrospective, case-control study, we reviewed the medical records of all patients evaluated for PE with MRA during a 5-year period along with age- and sex-matched controls evaluated with CTA. Only the first instance of PE evaluation during the study period was included. After application of our exclusion criteria to both study arms, the analysis included 1173 subjects. The primary endpoint was major adverse PE-related event (MAPE), which we defined as major bleeding, venous thromboembolism, or death during the 6 months following the index imaging test (MRA or CTA), obtained through medical record review. Logistic regression, chi-square test for independence, and Fisher’s exact test were used with a p?<?0.05 threshold.

Results

The overall 6-month MAPE rate following MRA (5.4%) was lower than following CTA (13.6%, p?<?0.01). Amongst outpatients, the MAPE rate was lower for MRA (3.7%) than for CTA (8.0%, p?=?0.01). Accounting for age, sex, referral source, BMI, and Wells’ score, patients were less likely to suffer MAPE than those who underwent CTA, with an odds ratio of 0.44 [0.24, 0.80]. Technical success rate did not differ significantly between MRA (92.6%) and CTA (90.5%) groups (p?=?0.41).

Conclusion

Within the inherent limitations of a retrospective case-controlled analysis, we observed that the rate of MAPE was lower (more favorable) for patients following pulmonary MRA for the primary evaluation of suspected PE than following CTA.

     

Clinical usefulness of adjusted D-dimer cut-off values to exclude pulmonary embolism in a community hospital emergency department patient population

Background Plasma D-dimer measurement is used in the assessment of the clinical probability of pulmonary embolism (PE), in order to minimize the requirement for pulmonary computed tomography angiography (CTA). Purpose To evaluate whether doubling the threshold value of serum D-dimer from 500 μg/L to 1000 μg/L could safely reduce utilization of pulmonary CTA to exclude PE in our emergency department patient population. Material and Methods Emergency department patients evaluated for PE with a quantitative D-dimer assay and pulmonary CTA were eligible for inclusion. D-dimer values were retrospectively collected in all included patients. Pulmonary CT angiograms were reviewed and scored as positive or negative for PE. Receiver-operating characteristic (ROC) analysis was used to determine the accuracy of quantitative D-dimer measurements in differentiating between positive and negative PE patients as per CTA. Results A total of 237 consecutive patients underwent pulmonary CTA and had a D-dimer measurement performed. Median D-dimer level was 1007 μg/L and in 11 (5%) patients the pulmonary CT CTA was positive for PE. The ROC curve showed an area under the curve (AUC) of 0.91 (P < 0.0001). Increasing the D-dimer threshold value of 500 μg/L to 1000 μg/L increased the specificity from 8% to 52% without changing the sensitivity. Conclusion Adjusting the D-dimer cut-off value for the emergency department community population and patient age increases the yield and specificity of the ELISA D-dimer assay for the exclusion of PE without reducing sensitivity.     

Spiral CT angiography and surgical correlations in the evaluation of intracranial aneurysms

We investigated the accuracy of spiral computed tomography angiography (CTA) in the detection and study of intracranial aneurysms by comparing CTA with selective angiograms and surgical findings. Twenty-six patients (9 men and 17 women; mean age 53.1 ± 1.8 years) with suspected intracranial aneurysms were submitted to CTA (1- to 2-mm slices, pitch 1:1, 24 s, RI = 1) after a conventional CT examination showing subarachnoid hemorrhage (SAH) in 19 cases and during neuroradiological investigations performed for other reasons in 7 cases. One hundred twenty to 150 ml iodate contrast agent (0.3–0.4 gI/ml) were injected intravenously at 5 ml/s rate and with 12- to 25-s delay calculated with a preliminary test bolus. Three-dimensional shaded surface display (3D SSD) and maximum intensity projection (MIP) reconstructions were obtained from axial images. Then, within 48 h, all patients were submitted to digital subtraction angiography (DSA), with separate assessment of CTA and DSA findings. Twenty-two aneurysms shown by CTA were confirmed at DSA and surgery (true positives), whereas the vascular lesion was not confirmed at DSA in 2 cases (false positives). The presence of intracranial aneurysms was excluded at both CTA and subsequent DSA in 7 cases (true negatives) and there were no false negatives; sensitivity was 100 %, specificity 77.8 %, and diagnostic accuracy 93.5 %. Computed tomography angiography aneurysm location was confirmed at surgery in all cases, with very high accuracy in assessing the presence of an aneurysm neck (100 %). Computed tomography angiography accurately depicted the aneurysm shape in 20 of 22 cases, but failed to depict its multilobed nature in 2 cases. The mean aneurysm diameter calculated at CTA was 0.99 ± 0.12 cm vs 1.09 ± 0.11 cm at surgery (p < 0.01). The present results suggest that the high sensitivity of CTA, if confirmed by further studies, might help in avoiding having to resort to arteriography after negative CTA in SAH patients. Received 15 July 1997; Revision received 30 September 1997; Accepted 5 November 1997     

Evaluation of pulmonary embolisms using coronal reformations on 64-row multidetector-row computed tomography: Comparison with axial images

OBJECTIVE: To evaluate coronal reformations of the chest on 64-row multidetector-row computed tomography (MDCT) for detection of pulmonary embolisms compared with axial images. METHODS: Thirty-eight consecutive patients who underwent pulmonary computed tomography angiography (CTA) on 64-row MDCT for a suspected pulmonary embolism were retrospectively studied. Contiguous 2-mm axial and coronal images were reviewed independently. A pulmonary embolism was assessed in the main, lobar, or segmental pulmonary arteries and was scored using a 5-point scale. RESULTS: A pulmonary embolism was demonstrated in 10% (4 of 38) of axial images and 16% (6 of 38) of coronal images. Interpretation was concordant in 95% to 100% of cases for a main or lobar pulmonary embolism and in 80% to 82% of cases for a segmental pulmonary embolism. Agreement of scores was almost perfect for a a main or lobar pulmonary embolism (mean weighted kappa value = 0.969) and moderate to good for a segmental pulmonary embolism (mean weighted kappa value = 0.560). CONCLUSION: Coronal reformations of the chest on 64-row MDCT were as informative as axial images for the detection of main, lobar, and segmental pulmonary embolisms.     

Challenges, controversies, and hot topics in pulmonary embolism imaging

OBJECTIVE: The purpose of this article is to discuss the diagnostic role of pulmonary CT angiography (CTA) in the workup of pulmonary embolism (PE), including specific populations, and issues such as pulmonary CTA combined with indirect CT venography; radiation dose considerations; the management of isolated subsegmental PE; and new technologic developments, such as dual-source/dual-energy pulmonary CTA. CONCLUSION: The role of pulmonary CTA will continue to grow with the emergence of MDCT and dual-energy CT and their improved capabilities. However, the need for any given CT examination should always be justified on the basis of the individual patient's benefits and risks.     

MRI for acute chest pain: Current state of the Art

This article reviews the magnetic resonance imaging (MRI) and angiography (MRA) techniques, imaging findings, and evidence for evaluating patients with acute chest pain due to acute pulmonary embolus (PE), aortic dissection (AD), and myocardial infarction (MI). When computed tomographic angiography (CTA) is contraindicated, MRI and MRA are important alternative imaging modalities for diagnosis and management of patients with acute PE, AD, and MI. Familiarity with the techniques, imaging findings, and evidence is critical to safely and appropriately managing patients presenting with acute chest pain. J. Magn. Reson. Imaging 2013;37:1290–1300. © 2013 Wiley Periodicals, Inc.     

CT perfusion image of the lung: value in the detection of pulmonary embolism in a porcine model

RATIONALE AND OBJECTIVES: We assess the value of computed tomography perfusion image (CTPI) obtained by postprocessing the CT data in the diagnosis of pulmonary embolism. METHODS: An experimental pulmonary embolism model was made in 6 pigs by injecting 2 types of emboli into the pulmonary arteries. For each pig, 5 type-A (diameter 3.5 x 8 mm) and 5 type-B (diameter 2.5 x 6 mm) emboli were injected through a catheter with the distal tip located in the inflow tract of the right atrium. After obtaining precontrast and postcontrast CT data during a single breath-hold using a 4-slice multidetector CT, perfusion images were generated by data subtraction. Approximately 150 to 180 mL of contrast material was injected at an injection rate of 6 mL/s to obtain postcontrast CT. Three independent observers twice analyzed CT images for the presence of emboli: once with postcontrast CT scans (CT angiography: CTA) alone and again with both CTA and CTPI. The locations of the emboli in the pulmonary arteries were confirmed by examining the killed porcine lungs. RESULTS: The sensitivity and positive predictive value in the detection of pulmonary emboli with CTA alone were 59% (106/180) and 87% (106/122), respectively. The sensitivity and positive predictive value with both CTA and CTPI were 87% (156/180) and 85% (156/184), respectively. For type-A emboli, the sensitivity with both CTA and CTPI (76/90, 85%) was better than that with CTA alone (63/90, 70%) (P < 0.001). For type-B emboli, the sensitivity with both CTA and CTPI (80/90, 89%) was also better than that of CTA alone (43/90, 48%) (P < 0.001). CONCLUSIONS: CTPI could be obtained using digital subtraction of the CT data. It appeared to be an adjunct in enhancing the diagnostic accuracy of pulmonary embolism, particularly when detecting small pulmonary emboli.     

Two-dimensional time-of-flight magnetic resonance angiography of renal arteries without maximum intensity projection: A prospective comparison with angiography in 21 patients screened for renovascular hypertension

Purpose We compared magnetic resonance angiography (MRA) with conventional angiography to establish its value as a screening test in the workup for renal hypertension.Methods Twenty one patients underwent MRA and angiography within a three day interval. Fifteen patients were suspected of having renovascular hypertension on the basis of clinical findings; the remaining six had multivessel atherosclerosis with renal insufficiency. MRA was performed on a 1 Tesla magnet in three planes: axial, coronal and perpendicular to the axis of each renal artery, by means of several contiguous or overlapping individual slice acquisitions. The two examinations were read by the same two independent observers, before and after an interval of 3 months.Results Conventional angiography showed 48 renal arteries. All main and three of six accessory renal arteries were correctly identified by MRA, as well as 11 of 14 significant stenoses or thromboses. Overreading of stenoses by MRA was observed in 4 cases. There were two false negatives for the two readers. The sensitivity and specificity of MRA for the detection of stenoses of the main renal arteries were found to be 70 and 78% respectively, for the first reading and 85 and 86% for the second reading.Conclusion MRA is considered a useful noninvasive method to determine the need for conventional angiography in patients in whom renal artery stenosis is suspected.Presented at CIRSE '92, Barcelona, Spain, 31 August 1992     

Clinically suspected pulmonary embolism: utility of spiral CT

PURPOSE: To prospectively determine the utility of contrast material-enhanced spiral computed tomography (CT) in the examination of patients clinically suspected of having pulmonary embolism (PE). MATERIALS AND METHODS: One hundred ten patients clinically suspected of having PE were examined with contrast-enhanced spinal CT and at least one other imaging modality: ventilation-perfusion scintigraphy, Doppler ultrasonography of deep leg veins, or pulmonary angiography. Chart review or telephone contact with the referring clinician was used to evaluate the contribution of spiral CT to the final clinical diagnosis. RESULTS: Spiral CT helped correctly identify 23 of 25 patients with PE (sensitivity, 92%). In 57 (67%) of the 85 patients without PE, spiral CT provided additional information that suggested or confirmed the alternate clinical diagnosis: pneumonia (n = 14), cardiovascular disease (n = 10), pulmonary fibrosis (n = 7), trauma (n = 6), malignancy (n = 5), pleural disease (n = 4), postoperative changes (n = 4), and other (n = 7). In the remaining 28 patients, spiral CT scans were normal (n = 12), failed to produce findings supportive of the final clinical diagnosis (n = 13), or were false-positive for PE (n = 3; specificity, 96%). CONCLUSION: Spiral CT has good sensitivity and specificity for the diagnosis of PE. In the majority of patients who do not have PE, it also provides important ancillary information for the final diagnosis.