Helical computed tomography and alternative diagnosis in patients with excluded pulmonary embolism

OBJECTIVE

A clinical diagnosis of pulmonary embolism (PE) is confirmed objectively in 20-30% of patients. Helical computed tomography (CT) can allow an alternative diagnosis to be made. The frequency and validity of alternative diagnoses on helical CT in consecutive patients presenting with clinically suspected PE was assessed.

PATIENTS AND METHODS

In all 512 prospectively analyzed patients helical CT scan was performed, and apart from presence or absence of PE, pathologic changes in lung parenchyma, mediastinum, cardiovascular system, pleura and skeleton were recorded. When possible an alternative diagnosis was given and compared with the final diagnosis after 3 months follow-up.

RESULTS

In 130 patients (25.4%) PE was excluded and an alternative diagnosis considered likely. In 123 of the 130 patients (94.6%) this diagnosis was unchanged at 3 months follow-up. The diagnoses included pneumonia (n = 67), malignancy (n = 22), pleural fluid (n = 10), cardiac failure (n = 10), COPD (n = 6) and a variety of other causes (n = 15). The diagnosis changed at follow-up in seven patients (5.4%). An initial diagnosis of pneumonia changed to malignancy in two patients and to pleuritis and cardiac failure in one patient each. In two other patients malignancy and chronic obstructive pulmonary disease (COPD) were ruled out and the diagnosis changed to pneumonia. In one patient the final diagnosis remained unknown after an initial suspicion of malignancy.

CONCLUSION

In clinically suspected PE helical CT allows a reliable alternative diagnosis to be made in 25.4% of patients. This feature is an unique advantage in comparison with other diagnostic tests and supports the decision of taking helical CT as first line test in suspected PE.

[The diagnosis of pulmonary embolism: the best strategies according to the results of a large Dutch multicentre study]

The Dutch national guidelines for the diagnosis of patients with clinically suspected pulmonary embolism (from 1992 en 1998) are poorly followed in clinical practice, due especially to practical objections. A large multicentre trial to investigate the diagnostic accuracy of the available modalities and of recently developed techniques such as D-dimer determination, (99m)Tc-gas-scintigraphy and spiral CT scanning was started in I997. In the first phase, the diagnostic value was assessed of: spiral CT (sensitivity 69%, specificity 84%; sensitivity for segmental and larger pulmonary embolisms (PE) 86% and for subsegmental PE 21%), (99m)Tc-gas-ventilation scintigraphy (no improvement compared to conventional ventilation scintigraphy), D-dimer determination (sensitivity for segmental PE 93% and for subsegmental PE 53%, specificity 63%), clinical decision rules (in combination with D-dimer determination; sensitivity 100%, specificity 11%) and echography of the deep venous system (sensitivity 26% for segmental PE and 7% for subsegmental PE, specificity 97%). In the second phase, the feasibility of two new potentially cost-effective diagnostic algorithms was evaluated on the basis of the results obtained in the first phase and data in the literature. In 631 patients, a clinical risk estimate was made and D-dimer determination was done, followed by a ventilation-perfusion scan and serial compression echography of the leg veins. An apparent recurrence of PE occurred in 6 of 466 patients in whom no PE had been found originally (1.3%; 95% CI: 0.5-2.8). The average costs were 812 Euro,--per patient. In 510 patients, a spiral CT followed by compression echography was performed. Recurrent PE occurred in 3 of 378 patients with initial normal tests (0.8%; 95% CI: 0.2-2.3). The average costs were 883 Euro,--per patient. A combination of both strategies can be cost-effective with a cost 674 Euro,--per patient (recurrence rate: 1.9%). Both the strategy starting with a clinical-risk estimate and a D-dimer determination as well as the strategy consisting of spiral CT and serial echography were safe and cost-effective. According to the results of a survey of hospital directors, internists and pulmonologists, both are well accepted in clinical practice.

Accuracy of single-detector spiral CT in the diagnosis of pulmonary embolism: a prospective multicenter cohort study of consecutive patients with abnormal perfusion scintigraphy

BACKGROUND

Spiral computed tomography (CT) has emerged as a potentially conclusive diagnostic test to exclude pulmonary embolism (PE) in patients with non-high probability scintigraphy and is already widely used-sometimes as the sole primary diagnostic test in the diagnosis of suspected PE. Its true sensitivity and specificity has, however, not been evaluated previously in a large cohort of consecutive patients.

METHODS

In a multicenter prospective study 627 consecutive patients with clinically suspected PE were studied. Patients with normal perfusion scintigraphy were excluded from further analysis. Single-detector spiral CT scanning and ventilation scintigraphy were then performed in all patients to diagnose PE, while pulmonary angiography was performed as the gold standard. The only exceptions were those patients who had both a high-probability VQ scan and a CT scan positive for PE: these patients were considered to have PE and did not undergo additional pulmonary angiography. All imaging tests were read by independent expert panels.

RESULTS

Five hundred and seventeen patients were available for complete analysis. The prevalence of PE was 32%. Spiral CT correctly identified 88 of 128 patients with PE, and 92 of 109 patients without PE, for a sensitivity and specificity of 69%[95% confidence interval (CI) 63-75] and 84% (95% CI 80-89), respectively. The sensitivity of spiral CT was 86% (95% CI 80-92) for segmental or larger PE and 21% (95% CI 14-29) in the group of patients with subsegmental PE.

CONCLUSION

The overall sensitivity of spiral CT for PE is too low to endorse its use as the sole test to exclude PE. This holds true even if one limits the discussion to patients with larger PE in segmental or larger pulmonary artery branches. We conclude that, in patients with clinically suspected PE and an abnormal perfusion scintigraphy, single-slice detector spiral CT is not sensitive enough to be used as the sole test to exclude PE.

The application of a Dutch consensus diagnostic strategy for pulmonary embolism in clinical practice

In The Netherlands, the 'Dutch consensus strategy' was formulated in 1993 as a diagnostic strategy for patients with suspected pulmonary embolism. Four years after its introduction, the application of this strategy was investigated. A questionnaire was sent to the hospital management and the departments of internal medicine and pulmonology of all Dutch hospitals. In total, 384 questionnaires were sent out. The response rates of the internists and pulmonologists were 63 and 65%, respectively. The specialists reported to have followed the consensus strategy in 75% of the patients seen the month prior to the questionnaire. However, analysis of only the last patient with the suspicion of pulmonary embolism revealed that the consensus strategy was followed in 55 of the 162 patients. As well, an overuse and an underuse of the different diagnostic facilities was documented. Furthermore almost a quarter of the patients were treated without an ascertained diagnosis, whereas 11% were not treated despite an improper exclusion of venous thrombo-embolism. Compared to a survey in 1994, the use of the 'Dutch consensus strategy' has not improved dramatically. In 34% of the patients, the consensus strategy was strictly followed (i.e. without any additional investigation); however in 67% of the patients a proper diagnosis was achieved. In any diagnostic strategy, two aspects should be considered. First the availability of the different facilities. Second the acceptance of the strategy by the physicians, involved in the diagnosis of patients with clinically suspected pulmonary embolism.

Availability of diagnostic facilities in the Netherlands for patients with suspected pulmonary embolism. ANTELOPE Study Group. Advances in New Technologies Evaluating the Localisation of Pulmonary Embolism

Pulmonary embolism remains a complex diagnostic problem. Although accurate and cost-effective, the 'Dutch consensus' strategy is not widely applied. We assessed the availability and investment plans of the different facilities used in this strategy. Furthermore, the current and future availability of new diagnostic modalities was investigated. A questionnaire was sent to all Dutch hospitals. The questionnaire contained separate sections with questions for the hospital management and the medical practitioners at the departments of radiology, nuclear medicine, internal medicine and pulmonology. Five hundred and eighty-four questionnaires were sent out (response rate 68%). Forty-three percent of the hospitals had no nuclear medicine facility, 11% had no pulmonary angiography facility, and 59% had no spiral CT scan (SCTA). Forty-six percent of the responding hospitals had a nuclear medicine facility; and 5% used Technegas for ventilation studies. Strategies with SCTA were available in about 27% of the hospitals. Due to future investments this number will increase to approximately 55%. Strategies with Technegas were available in 2.4% of the hospitals, this number might increase to 25% if Technegas is proven accurate. The 'Dutch consensus' strategy is available in two-thirds of the hospitals. All other strategies were less feasible. Several equivalent strategies for diagnosing pulmonary embolism should be developed. These strategies should be accurate, widely available and accepted.

Suspected pulmonary embolism: prevalence and anatomic distribution in 487 consecutive patients. Advances in New Technologies Evaluating the Localisation of Pulmonary Embolism (ANTELOPE) Group

PURPOSE

To evaluate the prevalence and anatomic distribution of pulmonary embolism (PE) in a group of consecutive patients clinically suspected of having PE.

MATERIALS AND METHODS

Four hundred eighty-seven consecutive patients clinically suspected of having PE were examined in six Dutch hospitals from May 1997 through March 1998. Patients underwent ventilation-perfusion (V-P) scintigraphy, spiral computed tomographic (CT) angiography, and/or digital subtraction pulmonary angiography according to a strict diagnostic protocol. Independent readers reviewed all of the diagnostic image studies in centralized readings. The largest pulmonary arterial branch in which PE was detected was recorded.

RESULTS

The prevalence of PE was 27% (130 of 487 patients). There was a significant difference in PE size between the high-probability and nondiagnostic V-P scans: The high-probability scans tended to depict larger emboli, but they also showed small subsegmental emboli. Twenty-nine (22%) of 130 patients had subsegmental PE; 23 of these 29 patients had a high-probability V-P scan.

CONCLUSION

The largest pulmonary arterial branch with PE was central or lobar in 66 (51%), segmental in 35 (27%), and isolated subsegmental in 29 (22%) patients.

Prevalence of deep vein thrombosis in suspected and proven pulmonary embolism: a meta-analysis

The purpose of this study was to determine the prevalence of lower extremity deep venous thrombosis (DVT) in patients with suspected and proven pulmonary embolism (PE). A meta-analysis was performed, based on literature from January 1983 to June 1997. Papers obtained from a computer-aided literature search were divided into studies with pulmonary angiography or ventilation-perfusion (V/Q) scintigraphy as the reference study. Our own observational data of the prevalence of DVT in 149 patients suspected of PE were also reported. The estimated prevalence of DVT in patients with proven and suspected PE was calculated. In the 149 patients studied, the prevalence of DVT was 12% with suspected PE and 32% (95% confidence interval 20-46%) in patients with proven PE. The individual studies showed a considerable heterogeneity, the prevalence of DVT in proven PE ranged from 10 to 93%. The pooled estimate of the prevalence of DVT in patients suspected of PE, over all studies, was 18% (95% confidence interval 15-20%). The DVT prevalence in proven PE was 36% (95% confidence interval 22-52%) in the angiography-based studies, and 45% (95% confidence interval 33-58%) in the V/Q scintigraphy-based studies. In conclusion, the current meta-analysis shows that the prevalence of DVT in suspected PE is approximately 18%, and in proven PE 36-45%.

Spiral CT appearance of resolving clots at 6 week follow-up after acute pulmonary embolism

PURPOSE

The purpose of this work is to describe the spiral CT appearance of resolving clots at 6 week follow-up in patients with acute pulmonary embolism (PE).

METHOD

Nineteen patients with acute PE initially identified with spiral CT scan underwent repeat CT examinations at 6 week follow-up after the start of anticoagulant therapy. The appearances of the clots on the initial CT scan and follow-up CT scan were analyzed.

RESULTS

Normalization of the pulmonary arteries at follow-up was seen in six patients (32%) only. Residual abnormalities were present in 13 of 19 patients (68%). Resolving clots were seen as eccentric wall-adherent filling defects (22%) or filling defects with central contrast material (3%).

CONCLUSION

Resolving clots after acute PE can be seen with follow-up CT scan in the majority of patients. It is important to be familiar with these findings.

An irreducible superior dislocation of the glenohumeral joint

The clinical features of a superior dislocation of the glenohumeral joint are described. Reposition, even under general anaesthesia, cannot be achieved. Associated supraspinatus tear, acromioclavicular separation and the dislocated position of the humeral head can be clearly visualized.

Pulmonary embolism: validation of spiral CT angiography in 149 patients

PURPOSE

To assess the reliability of spiral computed tomographic (CT) angiography of the pulmonary arteries in the diagnosis of pulmonary embolism (PE).

MATERIALS AND METHODS

One hundred forty-nine patients clinically suspected of having PE underwent spiral CT angiography and ventilation-perfusion (V-P) scintigraphy. Pulmonary angiography was also performed when the results of the V-P scan were indeterminate. Imaging results of spiral CT angiography were compared and validated against a normal perfusion scan in 40 patients, a high-probability scintigram in 53 patients, and a pulmonary angiogram in 56 patients.

RESULTS

Spiral CT angiograms were of satisfactory diagnostic quality in all 149 patients. The sensitivity of spiral CT angiography for the detection of PE was 94% (64 of 68 patients) (observer 1) and 82% (56 of 68 patients) (observer 2), and the specificity was 96% (78 of 81 patients) (observer 2). Good interobserver agreement was obtained for spiral CT angiographic results (kappa = .774). Spiral CT angiography proved to be effective in the detection of PE in pulmonary arteries up to the segmental level but not in the smaller subsegmental branches. Isolated subsegmental PE accounted for three false-negative spiral CT angiographic results for both observers.

CONCLUSION

Spiral CT angiography is an accurate method for the detection and exclusion of PE, with the exception of isolated subsegmental PE.

Role of spiral volumetric computed tomographic scanning in the assessment of patients with clinical suspicion of pulmonary embolism and an abnormal ventilation/perfusion lung scan

BACKGROUND

A study was carried out to evaluate the potential place of spiral volumetric computed tomography (SVCT) in the diagnostic strategy for pulmonary embolism.

METHODS

In a prospective study 249 patients with clinical suspicion of pulmonary embolism were evaluated with various imaging techniques. In all patients a ventilation/perfusion (V/Q) scan was performed. Seventy seven patients with an abnormal V/Q scan underwent SVCT. Pulmonary angiography was then performed in all 42 patients with a non-diagnostic V/Q scan and in three patients with a high probability V/Q scan without emboli on the SVCT scan. Patients with an abnormal perfusion scan also underwent ultrasonography of the legs for the detection of deep vein thrombosis.

RESULTS

One hundred and seventy two patients (69%) had a normal V/Q scan. Forty two patients (17%) had a non-diagnostic V/Q scan, and in five of these patients pulmonary emboli were found both by SVCT and pulmonary angiography. In one patient, although SVCT showed no emboli, the angiogram was positive for pulmonary embolism. In one of the 42 patients the SVCT scan showed an embolus which was not confirmed by pulmonary angiography. The other 35 patients showed no sign of emboli. Thirty five patients (14%) had a high probability V/Q scan, and in 32 patients emboli were seen on SVCT images. Two patients had both a negative SVCT scan and a negative pulmonary angiogram. In one who had an inconclusive SVCT scan pulmonary angiography was positive. The sensitivity for pulmonary embolism was 95% and the specificity 97%; the positive and negative predicted values of SVCT were 97% and 97%, respectively.

CONCLUSIONS

SVCT is a relatively noninvasive test for pulmonary embolism which is both sensitive and specific and which may serve as an alternative to ventilation scintigraphy and possibly to pulmonary angiography in the diagnostic strategy for pulmonary embolism.

Magnetic resonance imaging of the shoulder in patients with rheumatoid arthritis

To evaluate the ability of magnetic resonance imaging (MRI) to detect shoulder abnormalities 18 patients (36 shoulders) with rheumatoid arthritis (RA) and shoulder complaints were studied. Osseous abnormalities of the glenoid and humeral head were readily detected with MRI. The imaging planes used were not suitable for the evaluation of acromioclavicular joint involvement. Magnetic resonance imaging depicted soft tissue abnormalities that were not clearly visualised by plain film radiography, such as involvement of rotator cuff tendons and subacromial bursae, joint effusion, and muscular atrophy. Magnetic resonance imaging appears to be a sensitive method for evaluation of glenohumeral joint changes in patients with RA.

MR imaging of recurrent anterior dislocation of the shoulder: comparison with CT arthrography

Posttrauma damage due to anterior glenohumeral joint dislocation may result in recurrent dislocation. Currently CT arthrography is the method of choice to evaluate the extent of osseous and soft-tissue changes before reconstructive surgery. This study was undertaken to determine if MR was able to depict postdislocation abnormalities and if MR is a possible replacement for CT arthrography. Thirteen patients with recurrent anterior shoulder dislocation were evaluated with conventional radiography and MR; CT arthrography was performed in 10. Twelve patients underwent surgery, and the findings of MR and CT arthrography were verified. MR and CT arthrography showed the integrity of the glenoid labrum equally well. All humeral head defects, detected in nine patients with plain film radiography and CT, were easily identified with MR. Information about anterior joint capsule abnormalities is difficult to obtain with MR. However, separation of the capsule from the bony glenoid can be detected if a joint effusion is present to adequately distend the joint. Preliminary results of this study indicate that MR is useful in the assessment of postdislocation abnormalities and may possibly replace CT arthrography in the evaluation of patients with recurrent shoulder dislocation.

Rotator cuff impingement syndrome: MR imaging

Ten patients with clinically suspected rotator cuff impingement syndrome were evaluated with magnetic resonance (MR) imaging, double contrast arthrography, and conventional radiography. An area of increased signal intensity in the tendinous portion of the rotator cuff was seen in eight of ten patients on images obtained with a short repetition time (TR) and short echo time (TE) and those obtained with a long TR and long TE with spin-echo sequences. Microscopic findings, available in five patients, indicated that these areas of increased intensity corresponded to degeneration and inflammation of the rotator cuff. A previously injected long-acting steroid preparation combined with a local anesthetic, which also produces an area of increased signal intensity on long TR, long TE images, can cause problems with image interpretation. No tears of the rotator cuff were detected with MR imaging. However, a full-thickness cuff tear was detected with arthrography in three patients. Although based on a relatively small group of patients, these preliminary findings suggest that MR imaging is capable of demonstrating rotator cuff abnormalities in patients with impingement syndrome.

Magnetic resonance imaging of glenohumeral joint diseases

Through the application of oblique planes and flexible surface coil techniques, magnetic resonance imaging (MRI) promises to be of great clinical value in the evaluation of a variety of pathologic conditions affecting the shoulder. In patients with joint effusions, the tendinous portion of the rotator cuff, glenoid labrum, and bicipital tendon can be readily visualized. This capability has particular relevance in patients with inflammatory disease and traumatic conditions. Rotator cuff atrophy and impingement of the coracoacromial arc upon the supraspinatus muscle and tendon can also be demonstrated. MRI is also useful in the evaluation of shoulder instability.

Knee arthrography: a comparison of iohexol, ioxaglate sodium meglumine, and metrizoate

The arthrographic image quality and relative morbidity resulting from use of Omnipaque 300 (iohexol), Hexabrix 320 (ioxaglate sodium meglumine), and Isopaque Coronar 370 (metrizoate) were compared in a prospective double-blind study performed with 120 patients. Radiographs obtained 2, 5, 10, 15, 20, and 25 minutes after injection were judged for diagnostic quality. Relative morbidity was evaluated by the physician during the examination and later by the patient via a questionnaire. Hexabrix demonstrated the best and most persistent diagnostic quality over serial radiographs (P less than .05). Omnipaque caused significantly less postprocedural pain (P less than .05). The other types of discomfort measured did not indicate statistically significant differences in morbidity resulting from the three contrast agents.

Normal shoulder: MR imaging

Relatively poor spatial resolution has been obtained in magnetic resonance (MR) imaging of the shoulder because the shoulder can only be placed in the periphery of the magnetic field. The authors have devised an anatomically shaped surface coil that enables MR to demonstrate normal shoulder anatomy in different planes with high spatial resolution. In the axial plane, anatomy analogous to that seen on computed tomographic (CT) scans can be demonstrated. Variations in scapular position (produced by patient positioning) may make reproducibility of sagittal and coronal plane images difficult by changing the relationship of the plane to the shoulder anatomy. Oblique planes, for which the angle is chosen from the axial image, have the advantage of easy reproducibility. Obliquely oriented structures and relationships are best seen in oblique plane images and can be evaluated in detail.