E.6 PE diagnosis (V/Q scan) · 4) ventilation perfusion scintigraphy alone; was performed according to the procedures described in the PIOPED and the Advances in New Technologies

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Venous thromboembolic diseases Clinical evidence tables

E.6 PE diagnosis (V/Q scan)

In people with suspected PE, what it is the effectiveness of ventilation perfusion scans in detecting PE?

Study

details

Patients Diagnostic tools Measure of Disorders Results Comments

Gutte 2010a178

Study design:

Diagnostic

Prospective study

Duration of follow-up: at least 6 months

Patient group: Patients were eligible if there was a suspicion of pulmonary embolism (PE) , defined as an acute onset of new or worsening shortness of breath or chest pain without any obvious cause and with a positive D-dimer test (>0.5 mg/l) or a Wells score of more than 2.

Exclusion criteria: Allergy to iodine contrast agents, impaired renal function (P-creatinine>0.120 mmol/l/l), not willing

Assessment tool under investigation: three dimensional V/Q SPECT. The pulmonary SPECT included a perfusion SPECT study and a ventilation SPECT study obtained simultaneously within 13 minutes and performed immediately after the MDCT acquisition with the patient still in the supine position. V/Q SPECT was read blinded to clinical history of the patients, and the reviewers did not have access to the contemporaraneous chest radiograph.

Planar V/Q scintigraphy was viewed by reviewers blinded to the clinical history of the patient. 1

The CT protocol consisted of two successive acquisitions with the

V/Q SPECT

Sensitivity

Specificity

PPV

Composite +

Composite-

Total

VQ SPECT +

10 3 13

VQ SPECT -

0 20 20

Total 10 23 33

100%

87%

77%

100%

Funding:

None

Limitations: No information reported regarding severity of PE.

The V/Q SPECT has 3 patients missing from the analysis.

Additional

tests: blood pressure measurement, blood sample

Notes:

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to participate, lack of cooperation, absence of peripheral venous access, or technical issues

All patients N: 41 72 met inclusion criteria, 31 were excluded due to: allergy to iodine contrast agents (n=1), impaired renal function (n=21), decision not to participate in the study (n=4), lack of cooperation (, absence of peripheral venous access or technical issues (n=1). One was ineligible because of low clinical suspicion caused by Wells score less than 2 and negative D-dimer. Mean age (range): (mean (sd); 74 (15) among those with PE,

patients scanned in the supine position. The first acquisition consisted of a low-dose CT scan and the second MDCT acquisition consisted of a pulmonary MDCT angiography in suspended, deep inspiration.

The pulmonary MDCT angiography and V/Q SPECT were all performed using an integrated two headed y-camera and an MDCT (16 slice) manner.

Reference standard: Composite of MDCT, VQ spect and CT, clinical history, follow-up data, D-dimer, ECG, Ultrasound and Echocardia

NPV

Prevalence

Positive LR

Negative LR

Indeterminable (no reference available, due to suboptimal

technical quality of the datasets)

Non diagnostic rate

11/36 (31%)

7.7

0

5/41

8 (2-22)

Aim of study was to look head to head V/Q SPECT and Planar VQ scintigraphy

Planar VQ scintigraphy

MDCT A +

MDCT A-

Total

PlanarVQ+

7 7 14

Planar VQ -

4 18 22

Total 11 25 36

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71 (13) among those without PE Drop outs: 5/41 patients were excluded as final diagnosis was indeterminable due to suboptimal technical quality of the datasets.

Sensitivity

Specificity

PPV

NPV

Prevalence

Positive LR

Negative LR

Indeterminable(no reference available, due to suboptimal

technical quality of the datasets)

Non diagnostic rate

64%

72%

50%

82%

11/36 (31%)

2.28

0.5

5/41

0 (0-7)

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Study

details


Wang 2009455

Study design:

Diagnostic

Prospective study

Duration of follow-up: not reported

Patient group: patients in whom PE was suspected and gave informed consent, who had a normal creatinine level and were willing to undergo V/Q scan (or perfusion scan combined with CR) and CTPA were included in the study.

Exclusion criteria: pregnant women, patients who were currently experiencing circulatory shock or had hypotension or renal failure, were hemodynamically unstable, were on

Assessment tool under investigation: lung perfusion scans combined with ventilation (V/Q) scans and/or chest radiography (CR). Lung perfusion scan was performed using a single head gamma camera equipped with low energy, his resolution, parallel-hole collimators. All patients remained in supine position throughout the examination.

Reference standard: contrast enhanced multislice spiral CT pulmonary angiography (CTPA). CTPA studies were performed using a standard protocol.

VQ scans (n=28)

Sensitivity

Specificity

PPV

NPV

Positive LR

Negative LR

Non diagnostic results

CTPA

CTPA+ CTPA- Total

VQ+ 11 1 12

VQ - 1 13 14

Total 12 14 26

11/12 (91.7%)

13/14 (92.9%)

91.67%

92.86%

13.14

0.07

2/28 (7.1%) VQ; 0/28 CTPA

Funding:

No reported

Limitations: pulmonary angiography was not performed in all patients. V/Q scan (or perfusion scan combined with CR) was included as a component of the composite reference for determing absence/presence of PE, thus may introducing bias. V/Q scans were unavailable for the majority of patients to compare with CTPA.

Additional

tests:

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Study

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ventilatory support, had chronic pulmonary hypertension, received anticoagulation, or had a history of allergy to contrast media.

All patients N: 82 but only 28 were given V/Q scan Mean age (range): 51 years (14-81) Drop outs: 2 were nondiagnostic.

All patients underwent CTPA, lung perfusion scan and CR. 28 patients also underwent a V/Q scan. The perfusion scan combined with CR was used for the diagnosis of PE, thus, V/Q scan was not performed.

Sensitivity

Specificity

Prevalence

Positive LR

Negative LR

CTPA (overall results)

36/37 (97.3%)

37/38 (97.4%)

42/82 (51.2%)

32.33

10.03

Notes: Also results were presented from a segment based analysis of PE on Perfusion scan and CTPA.

Sensitivity

Specificity

Positive LR

Negative LR

Non diagnostic result

CTPA (n=28)

11/12 (91.7%)

14/14(100%)

-

0

0/28 (0%)

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Sensitivity

Specificity

Positive LR

Negative LR


Perfusion scan combined with CR (N=54)

22/25(88%)

22/24 (91.7%)

11

0.13

3/54 (5.6%)

Sensitivity

Specificity

Positive LR

Negative LR


CTPA (N=54)

25/25 (100%)

23/24 (95.8%)

25

0

2/54 (3.7%)

Non diagnostic result Overall results

V/Q scan or perfusion scan combined with CR; 5/82 (6.1%)

CTPA; 2/82 (2.4%)

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Study

details

Patients Diagnostic tools Measure of Disorders

Results Comments

Ohno 2004299

Study design:

Diagnostic

Prospective study

Duration of follow-up: 1 year

Patient group:

Patients believed to have a pulmonary embolism.

Exclusion criteria: patients younger than 18 years, pregnant, patients with renal failure were excluded.

All patients N: 48 Mean age (range): 55 years (27-73) Drop outs: none reported.

Assessment tool under investigation:

1) Time resolved contrast enhanced MR angiography alone

2) Contrast enhanced MDCT alone

3) contrast enhanced MDCT with time resolved contrast enhanced MR angiography (combined with SENSE)

4) ventilation perfusion scintigraphy alone; was performed according to the procedures described in the PIOPED and the Advances in New Technologies Evaluating the Localization of Pulmonary Embolism studies.

5) contrast enhanced MDCT with ventilation perfusion scintigraphy

Ventilation perfusion scintigraphy alone

Sensitivity

Specificity

PPV

NPV

Positive LR

Negative LR

PA

PA + PA- Total

VQ + 8 8 16

VQ - 4 28 32

Total 12 36 48

8/12 (67%)

28/36 (78%)

8/16(50%)

28/32 (88%)

3.05

0.42

Funding:

Daiichi Pharmaceutical Company

Limitations: 1) the overall prevalence of pulmonary emoblism was 25%, lower than that of the PIOPED STUDY. 2) They interpreted contrast enhanced 4-MDCT system for every 1.25mm section thickness, however if a thinner detector and reconstruction collimations was used, the diagnostic capability

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Study

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Results Comments

Reference standard: pulmonary angiography

Sensitivity

Specificity

PPV

NPV

Positive LR

Negative LR

Time resolved contrast enhanced MR angiography alone

11/12 (92%)

34/36 (94%)

11/13 (85%)

34/35 (97%)

15.3

0.08

of contrast enhanced MDCT in the peripheral vascular zone may be improved. 3) the sample size was small. Aim of study was to see if time-resolved MR angiography with SENSE was effective in diagnosing PE so not much data given for VQ.Indeterminate results not reported.

Additional

tests: none

Notes:

Sensitivity

Specificity

PPV

NPV

Positive LR

Negative LR

Contrast enhanced MDCT alone

10/12 (83%)

34/36 (94%)

10/12 (83%)

34/36 (94%)

13.83

0.18

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Results Comments

Sensitivity

Specificity

PPV

NPV

Positive LR

Negative LR

Contrast enhanced MDCT with time resolved contrast enhanced MR angiography

11/12 (92%)

34/36 (94%)

11/13 (85%)

34/35 (97%)

15.3

0.08

Sensitivity

Specificity

PPV

NPV

Positive LR

Negative LR

Contrast enhanced MDCT with ventilation perfusion scintigraphy

11/12 (92%)

34/36 (94%)

11/13 (85%)

34/35 (97%)

15.3

0.08

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Study

details


Results Comments

Prevalence 12/48 (25%)

Severity of PE 12/48 patients were diagnosed as having PE with a total of 35 central vascular zone and 41 peripheral vascular zone pulmonary embolisms.

Study

details


Gray 1990177

Study design:

Diagnostic

Study (not clear whether prospective or retrospective or mixed. The authors mentioned that they were careful to eliminate the

Patient group: patients who had just undergone or who were to undergo pulmonary angiography.

Exclusion criteria:

Not reported. All patients N: 78 (30 patients (38%) were non diagnostic and 48 (62%) had a diagnostic finding).

Assessment tool under investigation: ventilation perfusion scanning; images were obtained in the posterior projection using an IGE Maxicamera II with a standard low energy parallel collimator, with 3 min wash in and 3 min washout phases. An oblique ventilation study was performed 24 h later in some patients, as dictated by the perfusion scan finding.

Reference standard:

Pulmonary angiography;

VQ

Total (high and sign probability together)

Sensitivity

Specificity

PPV

NPV

PA

PA + PA- Total

VQ+ 15 1 15

VQ - 0 32 33

Total 16 32 48

100%

97%

93.75%

Funding:

Limitations:

It is unclear from the study design whether it was a prospective study with consecutive patients; 40% of patients had lung scanning before angiography, 20% on the same day and 40% had angiography before scanning.

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Study

details


error prevalent in retrospective studies, where angiography series are biased by excess patients with indeterminate lung scans)

Duration of follow-up: not clear

Mean age (range): 56 years (20-80) Drop outs: 30 were non-diagnostic. Total patients at start was 101, but fourteen were eliminated from the study because the lung scan or the chest radiograph was unavailable. Eight were excluded because angiogram was non-diagnostic (although table says 9 patients had an indeterminate pulmonary angiogram).

intraluminal filling defects or multiple cut-off vessels were reported as “pulmonary embolism”, normal angiography or minor perfusion abnormalities were reported as “no pulmonary embolism”.

Positive LR

Negative LR

Non diagnostic results

100%

33

0

30/78 V/Q; 9/78 PA.

Additional

tests: information collected on symptoms and signs (sudden dyspnoe, haemoptysis, pleuritic pain, history of PE/DVT, surgery/bed rest, radiograph, ECG change)

Notes:

VQ

Sensitivity (high probability)

Specificity (high probability)

PPV

NPV

Positive LR

Negative LR

PA

PA + PA- Total

VQ + 11 0 11

VQ - 0 32 32

Total 11 32 43

100%

100%

100%

100%

Cannot calculated

0

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VQ

Sensitivity (sign. probability)

Specificity (sign. probability)

PPV

NPV

Positive LR

Negative LR

PA

PA + PA- Total

VQ+ 4 1 5

VQ - 0 32 32

Total 4 33 37

100%

96.9%

80%

100%

33

0

3 month VTE rate Not reported.

Non diagnostic rate 30/78 (12/30 had PE in the pulmonary angiography and 19/30 did not have PE).

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Severity of PE 11/48 had PE present with a high probability, 4/48 had PE present with a significant probability, 32/48 had PE absent.

Mortality 1/13 in the scan positive patients who died had embolism; 2/24 in the indeterminate probability group died without autopsy; 1/28 in the scan negative group who died did not have embolism in the autopsy.

Study

details


Vreim 1990452

Study design:

Patient group:

Patients 18 years or older, inpatients and outpatients, in whom

Assessment tool under investigation: ventilation/perfusion scan; perfusion scans were satisfactory or better in 96% of cases,

High probability ventilation/perfusion

PA

PA+ PA- Total

VQ + 102 14 116

Funding: contracts NO1-HR-34007, NO1-HR-34008, -34009, -34010, -34011, -34012, -34013 from the National Heart,

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Study

details


Diagnostic

Prospective study

Duration of follow-up: 1 Year

symptoms that suggested pulmonary embolism were present within 24 hours of study entry and contraindications to angiography such as pregnancy, serum creatinine level greater than 260µmol/L or hypersensitivity to contrast material.

Exclusion criteria:

Patients with recurernces were not approached for recruitment a second time.

All patients N: 931 Mean age (range): 56.1 years Drop outs: 23/931 (2.5%) had incomplete (16/931) or no (7/931) follow-up.

ventilation scans adequate or better in 95%.

Reference standard:

Angiography; the femoral-vein Seldinger technique with a multiple side-holed, 6 F to 8F pigtail catheter was used. Pulmonary angiograms were adequate or better in 95% of cases.

scan

Sensitivity

Specificity

Prevalence

Positive LR

Negative LR

Non-diagnostic results

VQ - 149 466 615

Total 251 480 731

41%

97%

102/124

13.66

0.61

VQ: 105 with PE present on PA; 217 with PE absent on PA; PA: 24 uncertain. No angiogram in 175 patients.

Lung, and Blood Institute, Bethesda, Md.

Limitations: Clinical investigators made diagnosis of pulmonary embolism based on an agreed set of information but without standardized diagnostic algorithms. Random sample taken and no details of randomisation.

Additional

tests:

Notes: The authors suggested in the discussion that attention should be paid to the angiographic criteria’s design for acute pulmonary embolism, the variable time between angiographic

High or intermediate probability ventilation/perfusion scan

Sensitivity

Specificity

Prevalence

PA

PA+ PA- Total

VQ + 207 231 438

VQ - 44 249 293

Total 251 480 731

82%

52%

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1493 patients gave consent and a random sample was taking of 933 and 560 were not selected for sensitivity and specificity analyses. 2 scans were not completed n=931 and angiogram not completed for 176 patients, therefore n=755. PE was uncertain in 24/755. N=731

Positive LR

Negative LR

207/488

1.7

0.35

evaluation and the patients’ deaths, and the variability in pathophysiology and pathological interpretation of thromboemboli in evolution.

High, intermediate or low probability ventilation/perfusion scan

Sensitivity

Specificity

Prevalence

Positive LR

Negative LR

PA

PA + PA- Total

VQ + 246 430 676

VQ - 5 50 55

Total 251 480 731

98%

10%

246/800

1.08

0.2

Non diagnostic rate 24/755 (3%) of patients who completed angiography had angiograms in which the presence of thromboemboli was uncertain.

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Severity of PE Not reported

Mortality 1 patient died before the V/Q scan (unknown aetiology)/

hospital mortality: 9/931

Documents

E.6 PE diagnosis (V/Q scan) · 4) ventilation perfusion scintigraphy alone; was performed according to the procedures described in the PIOPED and the Advances in New Technologies