Int 吳易儒指導醫師 萬醫師

Case presentation

Present Illness #25773451

● 61 y/o female● Shotness of breath for 1 week● Lung cancer with brain metastasis● Cough with sputum, Dyspnea on

exertion● Bilateral lower limbs swelling● No chest pain, no cold sweating, no

fever

Physical Examination

● T/P/R 36.5/129/22● BP 101/56● BW 47 Kg● Conjunctive: Pale● Breath sound: Bibasilar crackles● Heart rhythm: Irregularly irregular

Lab data

Lab data

Lab data

EKG 2014/09/18

Vascular echo 2014/09/18

● There is some thrombosis over bilateral fem-popliteal vein, which causes partial occlusion.

● Duplex scanning of arteries:● Site Right Left Femoral vein (V) (V) Calf vein (V) (V)

CXR

Ventilation scan

Perfusion scan

CT

Diagnosis

● Pulmonary thromboembolism with bilateral Deep vein thrombosis

● SVC thrombosis● Lung ca with left pleural and

Pericardial effusion● Leukocytosis, etiology unspecified, to

exclude concomitant infection

Discussion: Acute pulmonary embolism

Int吳易儒�

Purpose

● To use Prospective Investigation of Pulmonary Embolism Diagnosis(PIOPED) II data to retrospectively determine1)sensitivity 2)specificityof V/Q scintigraphic studies

Background

● PIOPED II reported (v.s. PIOPED I)● CT angiography in PA to diagnose APE:

sensitivity=83%,specificity=96%● Venous phase CT venography:

sensitivity=90%,specificity=95%● Wells score helped yield positive/negative

predictive values greater than 90% in 89% of patients

● V/Q scintigrams make predictive values higher than 90% in 22% of patients

Background

● CT has replaced V/Q scanning since 2001, while it has limitations:○ Cost○ Radiation dose○ Contraindications: reduced renal function, iodine

allergy● Use PIOPED II data to determine the

sensitivity and specificity of V/Q scintigraphic studies

Materials and Methods

● Multicenter study● Two blinded PIOPED II central readers for

○ CT angiography○ Pulmonary DSA○ V/Q scanning

● Experienced physicians determine the Wells scores

Patients

(a) a diagnosis recorded at V/Q scanning and either (b) a Wells score recorded prospectively and a diagnosis of PE present or PE absent at CT angiography or (c) a diagnosis of PE present or PE absent at DSA.

Statistic Analysis

● Compare PIOPED II V/Q scan with DSA results

● if DSA not performed or no definitive result:● Compare V/Q scan with CT angiographic

results which concordant with Wells score● if + CT result: Wells score >2● if - CT result: Wells score <6

Patients and Readings

Patients and Readings

Positive predictive value in PIOPED II

Probability Portion %

High 89/102 87.2%

Intermediate 47/152 30.9%

Low 6/89 6.7%

Very low 24/415 5.8%

Normal 2/132 1.3%

Categorization of V/Q Scan Central Readings

Exclusion of intermediate and low probability

Sensitivity of PE present= 77.4% (89/115)Specificity of PE absent= 97.7% (541/554)26.5 % (241/910) was nondiagnostic73.5% (669/910) was high or very low probability or normal scan

Categorization of V/Q Scan Central Readings

● PE present (high probability) and PE absent (very low probability or normal) categories showed for acute PE:

● sensitivity=77.4%● specificity=97.7%● V/Q scintigram was categorized as PE

present or PE absent in 73.5% of patients

Discussion

● DSA is the most widely accepted imaging reference standard

● If no DSA result-> CT angiography concorcant with the Wells score due to:○ CTA and Wells score concordance associated with

high PPV and NPV○ The sensitivity/ specificity of V/Q scan without DSA

with only CTA and Wells score concordance= 85.1%/ 98.2%

Discussion

● In PIOPED II, fewer patients was low probabilities or normal, due to:

● Criteria for interpreting V/Q scans have improved considerably since PIOPED I

● Difference from V/Q scan reading depends on the patient (population, ex. p’t in ICU)○ PIOPED I: inpatients and critically ill○ PIOPED II: outpatients

Discussion

● Combine low proobability and very low probability due to similarity:○ Sensitivity= 73.6%, Specificity=98.0%○ Nondiagnostic= 16.7% of population

● Combine Wells score with V/Q categories: PPV or NPV >90%

Comparion of CTA and V/Q scan in PIOPED II

● More nondiagnostic results with V/Q scanning (26.5% of p’t) than CT (6.2% of p’t)

● Remove nondiagnostic studies-> V/Q and CTA have similar sensitivity and specificity (77% and 98%) (83% and 96%)

Discussion

DSA was not performed in all patients due to less use of invasive pulmonary angiographyPIOPED II supported CTA with Wells score as an alternative diagnostic reference to DSA

Conclusion

● V/Q scintigraphy ○ yields diagnostically definitive results○ an appropriate pulmonary imaging procedure

● in patients for whom CTA may be disadvantageous

Thanks for your attention