[Expert consensus on the operational protocol for radionuclide pulmonary ventilation/perfusion scintigraphy of pulmonary thromboembolism].

چکیده اصلی

Radionuclide pulmonary ventilation/perfusion (V/Q) imaging is an important non-invasive tool for diagnosing pulmonary thromboembolism (PTE) and is used for screening, follow-up, and assessment of treatment response of PTE and chronic thromboembolic pulmonary hypertension (CTEPH). Currently, hospitals in China differ in their use of planar and tomographic acquisition methods for V/Q imaging, and interpretation requires a high level of expertise among nuclear medicine physicians. After surveying the nuclear medicine departments of multiple hospitals and holding expert discussions, the working group developed the Expert consensus on the operational protocol for radionuclide pulmonary ventilation/perfusion scintigraphy of pulmonary thromboembolism. This consensus covers examination procedures, diagnostic approaches, and precautions, with the aim of standardizing the clinical application of V/Q imaging procedures and their clinical application in PTE diagnosis. The following recommendations were formulated.Summary of RecommendationsRecommendation 1: For ventilation imaging, 99mTc-Technegas is recommended as the preferred radiopharmaceutical. During the preparation of Technegas, the working group recommends wetting the crucible with anhydrous ethanol before the addition of the sodium pertechnetate solution to improve the efficiency and quality of Technegas generation. If Technegas is unavailable, 99mTc-Diethylenetriaminepentaacetic acid (99mTc-DTPA) aerosol may be used as an alternative (Consensus level: 100%).Recommendation 2: Routine supplemental oxygen is suggested before pulmonary perfusion imaging to prevent false-positive images caused by pulmonary vasospasm. The recommended oxygen flow rate is 2-4 L/min, with an inhalation duration of 5-10 minutes (Consensus level: 83.3%).Recommendation 3: For pulmonary perfusion imaging, 200 000-700 000 radiopharmaceutical particles (mean, approximately 400 000) should be administered, with the recommended activity of 120-240 MBq (3-6 mCi). For patients with severe pulmonary hypertension, conditions with right-to-left heart shunting, or a history of single-lung transplantation, the particle number should be reduced to 100 000-200 000 (Consensus level: 83.3%).Recommendation 4: Gently agitate and homogenize the suspension of 99mTc-macroaggregated human serum albumin (99mTc-MAA) prior to injection. With the patient supine and breathing at normal tidal volume, slowly inject the tracer over several respiratory cycles through a patent intravenous line, continuously monitoring for adverse reactions; discontinue immediately if discomfort occurs. Strictly avoid backflow of blood into the syringe, which may cause particulate aggregation and bolus formation, leading to artifactual hot spots (Consensus level: 100%).Recommendation 5: For patients with protein allergies, a routine skin test is recommended before pulmonary perfusion imaging. Inject 0.1 ml of 99mTc-MAA suspension into the appropriate part of the forearm and observe for 15-20 minutes. If there is no positive reaction, perfusion imaging can be proceeded, with close observation and emergency medications on standby. If the skin test is positive, pulmonary perfusion imaging is not recommended. Routine skin testing is not indicated in patients without a history of allergy (Consensus level: 83.3%).Recommendation 6: For the 2-day acquisition protocol, perform pulmonary perfusion imaging on the first day. If the result is abnormal, perform pulmonary ventilation imaging the following day to aid diagnosis; if the perfusion imaging result is normal, pulmonary ventilation imaging may be omitted (Consensus level: 83.3%).Recommendation 7: For pregnant women with suspected PTE, if V/Q imaging is considered necessary after clinical assessment, a 2-day protocol is recommended. Dose reduction is recommended for lung perfusion imaging, the recommended dose of 99mTc-MAA is 50 MBq (1.35 mCi) (Consensus level: 100%).Recommendation 8: When the 1-day acquisition protocol is used, perfusion imaging may be performed immediately after completion of ventilation imaging. To ensure the clarity and accuracy of pulmonary perfusion imaging, the perfusion count rate should be 3-4 times the ventilation count rate (Consensus level: 100%).Recommendation 9: Avoid ambiguous phrasing such as "possible pulmonary embolism" in image reports. Interpretations should provide a definitive conclusion, such as "pulmonary embolism present", "pulmonary embolism absent", or another specific conclusion, after excluding other causes of impaired pulmonary perfusion (e.g., Takayasu arteritis, mediastinitis or pulmonary arterial sarcoma). When the diagnosis remains uncertain, the report should state, "pulmonary embolism cannot be excluded; correlation with clinical findings and other imaging examinations is recommended" to support subsequent clinical assessment and therapeutic decision-making (Consensus level: 100%).Recommendation 10: For patients with CTEPH, visual semi-quantitative analysis (Begic/Meyer score) may serve as an adjunctive tool for efficacy assessment after percutaneous pulmonary balloon angioplasty (BPA) or pulmonary endarterectomy (PEA). Where institutional resources permit, structured reporting is encouraged to improve the clarity and reproducibility of segmental impairment documentation (Consensus level: 100%).

ترجمه فارسی چکیده

سنتیلوگرافی تنفسی/تزریقی رادیونوکلئیدی (V/Q) ابزاری غیرتهاجمی مهم برای تشخیص ترومبوآمبولی ریه (PTE) و ارزیابی پاسخ به درمان و بیماری‌های مرتبط است. این توافق‌نامه با هدف استانداردسازی روش‌های استفاده از این روش، شامل مراحل آزمایش، رویکردهای تشخیصی و نکات احتیاطی است.

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