- Deep venous thrombosis and pulmonary emboli can be diagnosed using MRI.
- D-dimer assays have a high positive predictive value in suspected venous thromboembolic disease.
- Duplex ultrasound is highly sensitive and specific investigation for symptomatic proximal leg deep venous thrombosis.
- The more distal the leg venous thrombosis, the more risk for pulmonary embolism.
- The dose of VQ (ventilation perfusion) scan is more than that for a CTPA (CT pulmonary angiogram).
Notes: DVT (Deep Venous Thrombosis) and PE (Pulmonary Embolism) are one of the major common challenges in day-to-day radiology practice. There are no common censuses or guidelines in the diagnosis and management of DVT or PE. D-dimer has a high negative predictive value, i.e. excluding DVT or PE, but it lackes positive predictive value. Duplex ultrasound remains investigation of choice in most of the hospitals to exclude or confirm DVT as this investigation is highly sensitive and specific (both >90%). VQ scan still remains a very common investigation in the diagnosis of PE and is based on PIOPED trail. Although conventional angiography is traditionally considered as a gold standard, CTPA is gaining wider acceptance in diagnosing PE, despite more dose than VQ scan. MRI is being tried in the diagnosis of PE and DVT by a technique (MRI-DTI, DTI= Direct Thrombus Imaging) which detects methhaemoglobin (M-Hb) and the initial results are promising.
Reference: Scarsbrook AF et al. Diagnosis of suspected venous thromboembolic disease in pregnancy. Clin Rad 2006: 61: 1-12.
